CHIAPAS, MEXICO Palenque

Alejandra Martínez-Melo

DECLARATIONS OF INTEREST: NONE MIOCENE ECHINOIDS FROM

Keywords: Agassizia, Clypeaster, Echinolampas, Miocene, Tulijá Formation, 36 Schizaster, Stomopneustes Agassizia, Brissopsis, Lajanaster, Eupatagus, Hernandezaster, Migliorinia and

Recent collecting in the Miocene Tulijá Formation near Palenque, Chiapas State of Mexico, has provided five species of echinoids: Stomopneustes pristinus, Echinolampas aldrichi, Clypeaster chiapasensis, Agassizia regia, and Schizaster dumblei; their reports are illustrated, measured and described. These new reports are a significant expansion of the known distribution of Stomopneustes pristinus and Agassizia regia, which were previously documented merely from their type localities; also, this is the first confirmed report of Schizaster dumblei in the Miocene. Neotype material is established for C. chiapasensis and discrepancies between previous descriptions have been resolved. The echinoid fauna of the Tulijá Formation shares species with the Meson and Tuxpan formations on the Gulf of Mexico and supports the description of the Tulijá Formation as a shallow marine paleoenvironment with high energy. With these revisions we start sketching an interesting system between the Caribbean and the Gulf of Mexico basin; due to the general quality of the fossil record and the scarce revisions on the paleofauna of the region, the present report help fill what has been a major gap in recognizing the distribution of echinoids. Highlights • Rediscovery of Stomopneustes pristinus and Agassizia regia, formerly only known by their type material. • Formal designation of neotype material and amended diagnosis of Clypeaster chiapasensis.

• New occurrences of Echinolampas aldrichi and Schizaster dumblei.

4

Introduction

The aim of this work is to provide a morphological description and updated taxonomical review of the Miocene echinoids from the Tulijá Formation, Chiapas, Mexico; this formation is located in the geographic region between the Caribbean Sea and the Gulf of Mexico.

Different authors have reported regional revisions on the Miocene faunas of echinoids (Fig. 1); [START_REF] Cooke | Cenozoic Echinoids of Eastern United States[END_REF] report the Cenozoic echinoids from the eastern USA, including taxonomic and geologic information of 18 Miocene species or subspecies from the Atlantic coast and the Golf Coastal Plain. [START_REF] Kier | Upper Miocene Echinoids from the Yorktown Formation of Virginia and Their Environmental Significance[END_REF] and [START_REF] Portell | Oligocene and Miocene Echinoids[END_REF] revised the echinoids from Yorktown Formation (upper Miocene-lower Pliocene) reporting the assemblage of Echinocardium orthonotum, Arbacia improcera, Psammechinus philanthropus, Mellita aclinensis and Spatangus glenni; this has affinities with echinoid assemblages from the upper Miocene or Pliocene of South Carolina and Florida.

The Cenozoic echinoid faunas of the northeastern part of Mexico were described by [START_REF] Dickerson | The Fauna of Medial Tertiary Formation and the Associated Horizons of Northeastern Mexico[END_REF] [START_REF] Israelsky | Notes on some echinoids from the San Rafael and Tuxpam beds of the Tampico Region, México[END_REF], [START_REF] Lambert | Note sur quelques Echinides recueillis par Mr. Walther Staub dans le Néogène de l'Est du Mexique[END_REF], [START_REF] Jackson | Mexican Fossil Echini[END_REF][START_REF] Caso | Los equinoideos fósiles del Cenozoico de México[END_REF]. Donovan et al. (2005a) described an internal mold of Echinocorys sp. cf. E. scutata Leske (Upper Cretaceous) and a test of Echinolampas sp. cf. E. aldrichi Twitchell for the Miocene of Belize. [START_REF] Durham | Miocene echinoids from the Valle Central, Costa Rica[END_REF] reported eight species from the Miocene in Turrucares, San Jose, Costa Rica: Echinolampas woodringi n. sp., Clypeaster sp. indet., Pericosmus israelsky n. sp., Schizaster costaricensis n. sp., Brissopsis n. sp., Schizobrissus kewi n. sp., Plagiobrissus costaricensis n. sp., P. malavassii n. sp; the most recent revision on the echinoids from Costa Rica lists 28

The stratigraphic terminology is based on Martinez-Ortiz et al. (2017) shows that the oldest rocks found in the region belong to the Angostura Formation (Fig. 2), dated as Campanian-Maastrichtian (Upper Cretaceous). Overlying the Mesozoic unit are the Tenejapa and Lacandon Formations, considered to be Paleocene in age. Because of the difficulty of differentiating the two formations, [START_REF] Alvarado-Ortega | Paleocene fishes from Palenque, Chiapas, southeastern Mexico[END_REF] combined them into the Tenejapa-Lacandón Unit. The overlying rocks have been identified as part of El Bosque and Lomut Formations of Eocene age. The youngest marine unit in this sequence is the Tulijá Formation, of early Miocene age. The Tulijá Formation is overlain by alluvial and polymictic conglomerates of continental origin ranging in age from the Pliocene to Holocene. The Tulijá Formation is represented by a 125 to 750 m thick sequence of dark brown-bluish clay strata interbedded with gray-reddish millimetric laminated limestones, and with sandy clays [START_REF] Bortolotti | Geología de las Provincias: Arco de La Libertad y la de Fallas de Transcurrencia, 1ra Etapa: Palenque-Agua Azul, IX Excursión Geológica al Sureste de México[END_REF][START_REF] Quezada-Muñetón | El Cretácico medio-superior, y el límite Cretácico superior-Terciario inferior en la Sierra de Chiapas[END_REF].

The Tulijá Formation is dated as early Miocene based on the faunistic association of Sorites marginalis, Archaias angulatus, Peneroplis sp., and Amphistegina sp. [START_REF] Bortolotti | Geología de las Provincias: Arco de La Libertad y la de Fallas de Transcurrencia, 1ra Etapa: Palenque-Agua Azul, IX Excursión Geológica al Sureste de México[END_REF][START_REF] Quezada-Muñetón | El Cretácico medio-superior, y el límite Cretácico superior-Terciario inferior en la Sierra de Chiapas[END_REF][START_REF] Sáenz-Pita | Tulijá, Formación[END_REF]. This formation is correlated with Caliza Macuspana Formation and is also isochronic with the Depósito Formation and the lower part of Ixtapa Formation [START_REF] Quezada-Muñetón | El Cretácico medio-superior, y el límite Cretácico superior-Terciario inferior en la Sierra de Chiapas[END_REF]. It represents a shallow water marine sequence deposited under cycles of changing sedimentary environments of high to low energy and frequent changing conditions, which reveal the transgression and regression events. Intermittent input of terrigenous sediments in this shallow marine platform is linked to the gradual uplift of the Chiapas region [START_REF] Meneses-Rocha | Tectonic Evolution of the Ixtapa Graben, an Example of a Strike-slip Basin of Southeastern Mexico: Implications for Regional Petroleum Systems[END_REF]. The Tulijá Formation was deposited into lagoons or internal platform (Pemex, 2004).

Collection

The echinoids discussed in this study were recovered from the Miocene Tulijá Formation between 2008 and 2018 at three localities near the town of Palenque, Chiapas (Fig. 3). Three sections were sampled at the El Gato site (recorded as IGM-loc 3636), one at the Don Eber site (IGM-loc 3879), and one at the Río Chacamax site (IGM-loc 3880) (Table 1). The fossils recovered include a large number of marine taxa, including foraminifera, ostracods, gastropods, bivalves, corals, crabs, echinoderms and fishes [START_REF] Bortolotti | Geología de las Provincias: Arco de La Libertad y la de Fallas de Transcurrencia, 1ra Etapa: Palenque-Agua Azul, IX Excursión Geológica al Sureste de México[END_REF][START_REF] Martínez-Ortiz | Ocurrencia de un decápodo braquiuro extinto, Necronectes proavitus (Rathbun, 1918), en los yacimientos marinos de la Formación Tulijá (Mioceno temprano) en las cercanías de Palenque, Chiapas, sureste de México[END_REF][START_REF] Alvarado-Ortega | The fossil fishes of the archaeological site of Palenque, Chiapas, southeastern Mexico[END_REF].

Preparation

The rock matrix was removed from the fossils alternating baths of 24x24 hours in clean water and Waller Solution. This solution consists of 71g of sodium citrate (Na3C6H5O7) and 8.5g of sodium bicarbonate (NaHCO3) per liter of distilled water; 20g of sodium dithionite (Na2S2O4) is added just when the bath is applied [START_REF] Maisey | Santana fossils: an illustrated atlas[END_REF]. Remaining limestone patches were removed with pin vices and needles under a binocular microscope. A last bath with sodium hydroxide (NaOH) was given in order to remove dust particles.

The specimens were photographed in the Coleccion Nacional de Paleontologia, Instituto de Geologia, UNAM, using a Nikon D80 camera and a Nikon AF-S NIKKOR 18-140 mm lens. The microphotography was performed in the Laboratorio de Microscopía y Fotografía de la Biodiversidad (II), Instituto de Biologia, UNAM, with the multi-focal macroscope Leica Z16 APO-A using Leica Application Suite software.

All referred specimens are deposited in the Coleccion Nacional de Paleontología, Instituto de Geología, Universidad Nacional Autónoma de México, Mexico City.

Institutional abbreviations

The acronyms of collections that house the specimens discussed in this study are: BYU, Brigham Young University, Provo, Utah, USA; CAS, California Academy of Sciences, San Francisco, California, USA; IGM, Colección Nacional de Paleontología, Instituto de Geología, Universidad Nacional Autónoma de México, Mexico City, Mexico; RGM, Naturalis Biodiversity Center, Leiden, Netherlands; USNM, Smithsonian, National Museum of Natural History, Washington, DC, USA.

Results

Systematic Paleontology

Class Echinoidea [START_REF] Leske | Jacobi Theodori Klein naturalis dispositio echinodermatum, edita et descriptionibus novisque inventis et synonomis auctorem aucta[END_REF] Order Stomopneustoida [START_REF] Kroh | The phylogeny and classification of post-Paleozoic echinoids[END_REF] Family Stomopneustidae [START_REF] Mortensen | Echinoidea: The Danish Ingolf-Expedition[END_REF] Genus Stomopneustes L. [START_REF] Agassiz | Monographies d'Echinodermes vivants et fossiles[END_REF] Type species-Echinus variolaris Lamarck, 1816, p. 47, by monotypy. Stratigraphic range-Eocene to Recent.

Diagnosis (sensu Smith and Kroh, 2011)-Apical system small, hemicyclic; ambulacra complex trigeminate, comprise large compound plates constructed of 3 to 5 variably sized triads overlapped by single large primary tubercle; ambulacral tubercles biserial, ambulacral pore-pairs form three discrete columns, offset to form wide zones above the ambitus.

Modern distribution-Not recorded from Mexico waters; the documented global distribution includes the Indian Ocean, and the coasts of Australia and the Philippines [START_REF] Worms | World register of Marine Species. Stomopneustes variolaris[END_REF].

Stomopneustes pristinus Jackson, 1937

Figures 4-5, Table 2. [START_REF] Jackson | Mexican Fossil Echini[END_REF], p. 229-230. Caso, 1951, p. 65. Kier and Lawson, 1978, p. 34.

Stomopneustes pristinus

Type specimens-Holotype USNM MO 496275 from the Oligocene, Meson Formation, Hacienda Tierra Amarilla, Alamo Temapache Municipality, Veracruz,

Mexico.

Geographical and time record-Otherwise known only from its type locality, Oligocene, Meson Formation, Veracruz, Mexico [START_REF] Jackson | Mexican Fossil Echini[END_REF].

Referred specimens-Sixteen specimens, IGM-S1 through IGM-S16.

Locality and age-IGM-loc 3880, Río Chacamax (Fig. 3); Miocene deposits of the Tulijá Formation, near Palenque town, northern Chiapas, Mexico.

Description-Test slightly conical in shape, subpentagonal in outline, with a diameter 57-105 mm; nearly flat on the oral side. Only one, disarticulated, apical disc found, with conspicuous gonopores situated towards outer point of genital plates. Ambulacral plating trigeminate, large compound plates constructed from between 3 and 5 variably sized, overlapped by a single large primary tubercle. Pore-pairs in oblique triads forming broad adradial bands; scattered adjacent small tubercles. Interambulacral plates wider than tall, almost double the width of ambulacral plates. Single central primary tubercle; flanking secondary tubercles, almost the same size on ambital and adoral plates. Interambulacral columns with two vertical columns of tubercles from apical disc to peristome; additional columns start at the fifth plate from the apical disc, increasing to three primary tubercles per plate at the ambitus. Primary tubercles inperforate and noncrenulate; few smaller secondary tubercles. Spines short and broad, with slight linear ornamentation. Peristome small, with sharp buccal notches. Aristotle's lantern stirodont. Nisiyama, 1966: IGPS 73728, from Upper Eocene (Lutetian, Orthophragmina-Globigerina Zone), beach rock on Nishiura, Hahajima, Bonin Islands, Japan. Stomopneustes pristinus Jackson, 1937: USNM 496275 (holotype), from Oligocene deposits, El Meson, Hacienda Tierra Amarilla, about 7 km northwest of the town of Temapache, Canton Tuxpam, Veracruz, Mexico.

Comparative material-Stomopneustes antiquus

Remarks-

The genus Stomopneustes Agassiz, 1841, includes four nominal species: 1) the type species Stomopneustes variolaris (Lamarck, 1816), known both living and fossil (Smith and Kroh, 2011), is commonly known as the black-sea urchin or the longspined sea urchin, and is widely distributed along the southern Pacific and in the Indian Ocean. Fossils of S. variolaris have been collected in Miocene marine deposits of Sindangbarang, Cidamar, northern Java, Indonesia (RGM, 2019); 2) the earliest occurrence of the genus is Stomopneustes antiquus [START_REF] Nisiyama | The echinoid fauna from Japan and adjacent regions. Part I[END_REF], from the Lutetian (Eocene) sediments of Nishiura Beach, Hahajima, Bonin Islands, Japan; 3) Stomopneustes pristinus [START_REF] Jackson | Mexican Fossil Echini[END_REF], an extinct species from the Oligocene marine deposits exposed in the Hacienda Tierra Amarilla, Alamo Temapache Municipality, Veracruz, Mexico, and 4) Stomopneustes atropurpurea Tenison-Woods, 1880, from the northeastern coast of Australia is likely a junior of synonym of S. variolaris [START_REF] Rgm | Naturalis Biodiversity Center[END_REF].

S. antiquus displays a comparatively depressed shape, whereas S. variolaris and S. pristinus share a more pyramidal lateral outline. Finally, the primary and secondary tubercles on the ambital interambulacral plates are of similar size in S. pristinus, but the primary tubercles are clearly smaller than the secondary tubercles in S. antiquus and S. variolaris [START_REF] Jackson | Mexican Fossil Echini[END_REF][START_REF] Nisiyama | The echinoid fauna from Japan and adjacent regions. Part I[END_REF].

Order Echinolampadoida [START_REF] Kroh | The phylogeny and classification of post-Paleozoic echinoids[END_REF] Family Echinolampadidae [START_REF] Gray | Description of two new genera and some new species of Scutellidae and Echinolampidae in the Collection of the British Museum[END_REF] Genus Echinolampas [START_REF] Gray | An attempt to divide the Echinida, or sea eggs, into natural families[END_REF] Type species-Echinanthus ovatus [START_REF] Leske | Jacobi Theodori Klein naturalis dispositio echinodermatum, edita et descriptionibus novisque inventis et synonomis auctorem aucta[END_REF] Stratigraphic range-Eocene to recent (Smith and Kroh, 2011).

Diagnosis (sensu [START_REF] Kier | Revision of the cassiduloid echinoids[END_REF])-Medium to large forms, often with high test, elongate to circular outline; apical system monobasal. Ambulacra petaloid, moderately developed, sometimes lanceolate, open or closing distally; poriferous zones usually unequal length, interporiferous zones wide; single pores in ambulacral plates beyond petals. Periproct inframarginal, transverse. Peristome transverse, pentagonal; bourrelets well developed; phyllodes single pored, usually moderately developed, with from two to three series of pores in each half-ambulacrum; buccal pores present. Tubercles adorally same size as adapically; usually narrow naked granular zone in interambulacrum 5.

The genus Echinolampas had its greatest diversity in the Paleogene [START_REF] Durham | Miocene echinoids from the Valle Central, Costa Rica[END_REF], and is represented by the extant species E. depressa from the southern platform of the Gulf of Mexico and the neritic zone of the Mesoamerican Caribbean, Sea where it inhabits depths from 183 to 329 m [START_REF] Martínez-Melo | Taxonomía y biogeografía ecológica de los equinoideos irregulares (Echinoidea: Irregularia) de México[END_REF].

Echinolampas aldrichi Twitchell, 1915

Figures 6-7, Table 3. [START_REF] Clark | The Mesozoic and Cenozoic Echinodermata of the United States[END_REF], p. 173, pl. LXXXI, fig. 1a-d, 2. Cooke, 1942, p. 38. Cooke, 1959, p. 55, pl. 22, fig. 11-13. Gordon, 1963, p. 637, pl 81, figs. 1, 2. Buitrón, 1974, p. 40-41, lam. 3, fig. 4, lam. 4, fig. 1-3. Donovan et al., 2005a, p.323-325, fig. 1. Type specimens-Holotype USNM MO 559490 and paratype USNM MO 563349 from the lower Oligocene, Gainestown, and Choctaw Bluff, Alabama River, Alabama; Mississippi (exact locality unknown [START_REF] Clark | The Mesozoic and Cenozoic Echinodermata of the United States[END_REF]).

Echinolampas aldrichi Twitchell in

Geographical and time record-From the Oligocene (Chattian) in the Chickasawhay Marl, Alabama and Mississippi, USA [START_REF] Cooke | Cenozoic Irregular Echinoids of Eastern United States[END_REF][START_REF] Cooke | Cenozoic Echinoids of Eastern United States[END_REF]; the Lares Limestone of Puerto Rico [START_REF] Gordon | Middle Tertiary echinoids from Puerto Rico[END_REF], dated as Oligocene [START_REF] Giusti | Water resources of the north coast limestone area, Puerto Rico[END_REF], and the Oligocene marine deposits at Simojovel, Chiapas, Mexico [START_REF] Buitrón | Algunos equinoides (Echinoidea) del Oligoceno de Chiapas[END_REF]. From the Miocene in Barrios Formation, middle Miocene to Quaternary, Belize (Donovan et al., 2005a) and Italy (USNM, 2019).

Referred specimens -Five specimens, IGM-E1through IGM-E5.

Locality and age-IGM-E1 is from the Don Eber site (IGM-loc 3879) and IGM-E2-5 are from the Río Chacamax site (IGM-loc 3880; Fig. 3). Miocene deposits of the Tulijá Formation exposed near town of Palenque, northern Chiapas, Mexico.

Description-Test from 68 to 79 mm in length. Outline at ambitus ovoid with the maximum width 61-75 mm posterior; conspicuous projection at the posterior margin. In lateral view, test swollen at the anterior ambulacra, with apical system at apex, slightly anterior; test height 26-35 mm. Ambulacra petaloid, almost reaching the ambitus, greatest width 2/3 length towards the ambitus, and closing distally. Anterior paired petals diverge 120°; posterior paired petals diverge 70°. The two rows of pore pairs are uneven in the anterior pair of petals (II and IV), the anterior row 80 % length of the posterior one. Pore pairs connected by very shallow groove; interior pore oval, exterior pore transversally elongated. Peristome wide and short, with conspicuous phyllodes, and small single pores connecting the phyllodes with the petaloids. Periproct oval, as wide as the peristome, inframarginal, reaching posterior margin of the ambitus.

Comparative material-Echinolampas aldrichi Twitchell, 1915: USNM MO 559490 (holotype) and IGM 2555, from Oligocene marine deposits at Simojovel, Chiapas, Mexico. Although this IGM specimen is lost Buitrón-Sánchez (1974) provided valuable photographs and data of this fossil that are considered in the present study.

Echinolampas tanypetalis [START_REF] Harper | A new Echinolampas (Echinodermata: Echinoidea) from the Ocala Limestone of Florida[END_REF]Shaak, 1974: BYU 1466 (holotype), from upper Eocene Ocala Formation, Florida, USA. Echinolampas woodrigni [START_REF] Durham | Miocene echinoids from the Valle Central, Costa Rica[END_REF] USNM 563424 (holotype) and USNM 563455 (paratypes) from Miocene marine deposits of Valle Central, Costa Rica. Echinolampas sp: IGM 5918 (recorded as sp. A) and IGM 5919 (recorded as sp. B), from the Lower Eocene of Bateque Formation, Baja California Sur, Mexico.

Remarks-

The genus Echinolampas includes about 120 nominal species [START_REF] Kroh | World Echinoidea Database. Echinolampas Gray, 1825 through World Register of Marine Species[END_REF], including living species distributed worldwide, and fossil species dating back to the Eocene recovered from marine deposits near the coasts of the Mediterranean Sea, Caribbean Sea, Gulf of Mexico, as well as parts of the Indian Ocean and Pacific Ocean. In Mexico, this genus is represented by the extant species Echinolampas depressa Gray, 1851, which inhabits various marine areas between 183 and 329 m in the southern platform of the Gulf of Mexico, and the neritic zone and slope of the Mesoamerican Caribbean [START_REF] Martínez-Melo | Taxonomía y biogeografía ecológica de los equinoideos irregulares (Echinoidea: Irregularia) de México[END_REF].

Echinolampas aldrichi is characterized by a wide morphological range. The type of E. aldrichi, as well as the specimens described by [START_REF] Cooke | Cenozoic Echinoids of Eastern United States[END_REF], have a rounded outline and a slender test with a sharp apex coincident with the apical system, while the specimens described here, those described from Simojovel, Chiapas by [START_REF] Buitrón | Algunos equinoides (Echinoidea) del Oligoceno de Chiapas[END_REF] and those from Belize by Donovan et al. (2005a) present an oval outline with a rounded apex, posterior to the apical system. The petals in E. aldrichi from Palenque are wider and longer than in the type specimen, with lanceolate petals, widest at 2/3 of their length closed distally; the petaloid ambulacra are comparatively slender and straighter in the Belizean echinoid.

A late Eocene fossil representative of Echinolampas was described from the Gulf of Mexico region as E. tanypetalis Harper and Shaak, 1974; the description of this species seems to fit in this wide morphological range of Echinolampas aldrichi, but a deeper research on intra and interspecific differences would be necessary in order to recognize a possible synonymy or confirm the validity of E. tanypetalis.

Another fossil representative of Echinolampas from the Caribbean region was described by [START_REF] Durham | Miocene echinoids from the Valle Central, Costa Rica[END_REF]

Clypeaster chiapasensis (Müllerried, 1951)

Figure 8, Table 4. Müllerried, 1951, p. 209-227, figs. 1-7. Chypeaster chiapasensis. Caso, 1956, p. 502-505, figs. 4-5. Kier andLawson, 1978, p. 55.

Clypeaster chiapanensis

Note-

The type specimens of this species are from an uncertain site near Palenque, Chiapas, Mexico (Müllerried, 1951). The two specimens referred to this species by [START_REF] Caso | El género Clypeaster Lamarck 1801, en el Terciario de México[END_REF] are from Miocene deposits near Pueblo Nuevo, Solistahuacan, and from the Chacamax River; both located into Chiapas, Mexico. Currently all these fossils are lost.

Referred specimens-Twenty-two specimens, IGM-C2 through IGM-C24.

Locality and age-IGM-loc 3636, El Gato site (Fig. 3). Miocene deposits of the Tulijá Formation exposed near the town Palenque, northern Chiapas.

Description-Test large (length 57-105 mm) and low (12-23 mm), outline at ambitus oval to subpentagonal, wider in the posterior half; Apical system central, with four genital pores; Apex slightly posterior; Petaloid area forming a low dome behind the apical system; Wide concave petaloid ambulacra; the anterior pair of petals shorter than the others, closing distally, ovate, with its maximum width from 1/2 to 2/3 the length; ambulacra I, III and V longer than II and IV; long plates between each pore of a pair of the ambulacrum. Petaloid 2/3 of the length of the radius of the test. Oral surface flat, presenting 5 funnels at the position of the ambulacra, running form the ambitus to the central peristome. Periproct at the aboral side, rounded, separated from the ambitus the same distance as the diameter of the periproct. Interporiferous zone twice the wide of the petal. Oral surface not flat, with sunken interambulacra towards the peristome. Both surfaces present numerous small tubercles, probably supporting small thin spines. The interior of the test presents thin numerous pillars between the two surfaces, in the interambulacral areas.

Nomenclatural act-Clypeaster chiapasensis (Müllerried, 1951), was erected based on two specimens from an imprecise site near Palenque. Müllerried made a detailed description of the two specimens but did not provide catalog or collection information for the type specimens of C. chiapasensis, which today are presumed lost. Review of the Type and Historic collection of the Colección Nacional de Paleontología (IGM) confirmed that those specimens are not deposited there, and no specimens were found in the collections of the Museo de Paleontología "Eliseo Palacios Aguilera", Tuxtla Gutiérrez, Chiapas, Mexico (com. pers. Carbot-Chanona).

When Müllerried (1951) described the species, he uses the epithet "chiapanensis" a misspelling that Caso (1956) corrected using "chiapasensis", due to the distribution in Chiapas, describing two specimens of C. chiapasensis from Pueblo Nuevo, Solistahuacan and Chacamax River, Chiapas, but provided no data for the specimen depository. She stated that the specimens differ from the description of Müllerried because they present: a) suboval ambitus, b) same length in all paired petaloids, but shorter than the anterior petaloid (III), and c) oval periproct, limiting with the edge. The wide phenotypic variety noted among specimens collected for this study would include both the type of Müllerried and Caso specimens.

There is the need to clarify the taxonomic status and the type locality of the nominal taxon due to the reasons previously explained: 1) the lack of type series and type locality, 2) the discrepancies of the descriptions made by Müllerried (1951) and [START_REF] Caso | El género Clypeaster Lamarck 1801, en el Terciario de México[END_REF], 3) the variety of shapes found in sample here described, and 4) the lack of a formal correction of the spelling].

Following the Article 75 of the ICZN (1999) for the stablishment of neotypes, I present the nomenclatural act for 1) correcting the specific epiteth and 2) stablish the neotype for Clypeaster chiapasensis (Müllerried, 1951) and the type locality, with its amended diagnosis.

Type specimen-IGM-C1 (Figure 8A-D).

Type locality and age-

Remarks-

The genus Clypeaster appears to have originated in the late Eocene and is represented by numerous species in the global modern faunas (Smith and Kroh, 2011). The living forms inhabit depths from 2 to 500 m [START_REF] Serafy | Echinoids (Echinodermata: Echinoidea). Memoirs of the Hourglass Cruises[END_REF] in all tropical biogeographic regions, with the exception of the continental slope of the Mexican Pacific Ocean [START_REF] Martínez-Melo | Taxonomía y biogeografía ecológica de los equinoideos irregulares (Echinoidea: Irregularia) de México[END_REF].

Clypeaster chiapasensis resembles Clypeaster pileus [START_REF] Israelsky | Notes on some echinoids from the San Rafael and Tuxpam beds of the Tampico Region, México[END_REF], from the Middle Oligocene to Lower Miocene Meson Formation of the Hacienda Tierra Amarilla, Alamo Temapache Municipality, Veracruz, Mexico [START_REF] Dumble | Geology of the northern end of the Tampico Embayment Area[END_REF].

Clypeaster pileus has narrower petal III (43% of the length) than the petals of C. chiapasensis (52% of the length). Specimen IGM 2553, reported by [START_REF] Buitrón | Algunos equinoides (Echinoidea) del Oligoceno de Chiapas[END_REF] as C. pileus, from the Oligocene deposits of Simojovel, Chiapas, differs significantly from CAS 370, holotype of C. pileus. The test of IGM 2553 is oval and has lanceolate petals with maximum width in the center of the petal length; the holotype, CAS 370, has a pentagonal test with ovoid petals with the maximum width nearer to their distal termination. [START_REF] Buitrón | Algunos equinoides (Echinoidea) del Oligoceno de Chiapas[END_REF] reported Clypeaster rogersi from the Oligocene of northern Chiapas along the Teapa River, near Teapa. The material that [START_REF] Buitrón | Algunos equinoides (Echinoidea) del Oligoceno de Chiapas[END_REF]

Agassizia regia Israelsky, 1924

Figure 9, Table 5. Israelsky, 1924, p. 142.

Agassizia regia

Type specimens: Holotype CAS-IG 363 from Eocene-Oligocene, Tuxpam Beds, Tampico Region, Mexico.

Geographical and time record-Reported from the Eocene-Oligocene, Tuxpam Beds, Tampico Region, Mexico [START_REF] Israelsky | Notes on some echinoids from the San Rafael and Tuxpam beds of the Tampico Region, México[END_REF].

Referred specimens-Fifty-three specimens, IGMA1 through IGMA53.

Locality and age-Specimens discussed herein were collected from the Tulijá Formation at IGM-loc 3636, El Gato site, near Palenque, northern Chiapas, Mexico (Fig. 3).

Description-Small (length 16-27 mm) almost spherical test (width 13-23 mm and height 13-20 mm), more rounded anteriorly than posteriorly, slightly flat near the periproct. Apex slightly posterior, at the apical system, which has four genital pores.

Anterior ambulacrum (III) non-petaloid, in slight furrow, with no visible pores. Ambulacra petaloid, II and IV divergent at 120°, petals almost reaching the ambitus; anterior series of pore pairs atrophied, the posterior row with conspicuous pairs of elongated pores. Anterior paired petals depressed, posterior petals short, more depressed than anterior pair, width about one-third the length. Petals I and V 2/3 the length of the anterior pair of petals, lacking interporiferous zones. Periproct high on the posterior the test, horizontally ovate. Peripetalous fasciole unindented in the interporiferous area, extends below the anterior petals; lateroanal fasciole extends from below the periproct upward to point of juncture with peripetalous fasciole, then downward anteriorly to below ambitus in anterior ambulacrum. Oral surface more swollen at the interambulacra 5. plastron strongly elevated, ornamented with closely spaced scaly tubercles. Peristome reniform, extremely anterior, at 17% of the length, labiate posteriorly.

When Israelsky described Agassizia regia, he established some of previous reports of

Agassizia clevei Cotteau, 1917 as synonyms; their morphology is similar, but they distinguish mainly in the lateral fasciole, which is much steeper in A. regia than in A. clevei [START_REF] Israelsky | Notes on some echinoids from the San Rafael and Tuxpam beds of the Tampico Region, México[END_REF]. [START_REF] Zachos | Echinoid fauna from the Late Oligocene (Chattian) reef at Damon Mound, Brazoria County, Texas. Paleogeography, Paleoclimatology[END_REF] suggested that Agassizia mossomi Cooke, 1942 (USA) could be conspecific with A. regia [START_REF] Israelsky | Notes on some echinoids from the San Rafael and Tuxpam beds of the Tampico Region, México[END_REF]A. clevei Cotteau, 1875; more detailed work is needed in order to formally characterize genera Agassizia, its phylogenetic relationship with Anisaster Pomel, 1886, the species included in each genus and correct stablishment of synonyms.

Family Schizasteridae [START_REF] Lambert | Échinides du sud de la Tunisie environs de Tatahouine[END_REF] Genus Schizaster L. Agassiz, 1836 Type species-Schizaster studeri L. Agassiz, 1836:185. Modern distribution in Mexico-Schizaster floridiensis [START_REF] Kier | Echinoid distribution and habits, Key Largo coral reef preserve, Florida[END_REF] is the only modern species of Schizaster documented from Mexican waters, and is reported from offshore of Puerto Morelos, Quintana Roo, at 17 m depth [START_REF] Martínez-Melo | Taxonomía y biogeografía ecológica de los equinoideos irregulares (Echinoidea: Irregularia) de México[END_REF].

Schizaster dumblei Israelsky, 1924

Figure 10, Table 6. Israelsky, 1924, p. 141.

Schizaster dumblei

Type specimens-Holotype CAS-IG 368 from the middle Oligocene to lower Miocene marine deposits of the Meson Formation, exposed in the Hacienda Tierra Amarilla, Alamo Temapache Municipality, Veracruz, Mexico.

Geographical and time record-From the Eocene of Cuba (Sanchez-Roig, 1953); from the middle Oligocene to lower Miocene of the Meson Formation, Veracruz, Mexico [START_REF] Israelsky | Notes on some echinoids from the San Rafael and Tuxpam beds of the Tampico Region, México[END_REF]. Possibly from the Chapelton Formation, mid-lower to midmiddle Eocene, Jamaica [START_REF] Donovan | Jamaican Cenozoic Echinoidea[END_REF].

Referred specimens-3 specimens, IGM-Sc1 through IGM-Sc3. Remarks-Schizaster is a cosmopolitan echinoid genus that includes both living and fossils species that range from the Eocene to the Recent (Smith and Kroh, 2011). There is currently a single report of a living Schizaster in Mexico, S. floridiensis [START_REF] Kier | Echinoid distribution and habits, Key Largo coral reef preserve, Florida[END_REF], occurring in the Neritic zone and Continental slope of the Mesoamerican Caribbean Sea, in front of Puerto Morelos, Quintana Roo, at 17 m depth [START_REF] Martínez-Melo | Taxonomía y biogeografía ecológica de los equinoideos irregulares (Echinoidea: Irregularia) de México[END_REF].

Locality and age-

Schizaster dumblei [START_REF] Israelsky | Notes on some echinoids from the San Rafael and Tuxpam beds of the Tampico Region, México[END_REF] resembles Schizaster scherzei [START_REF] Gabb | Descriptions of Caribbean Miocene fossils[END_REF]Schizaster costaricensis Durham, 1961. Nonetheless, the petals of Schizaster dumblei are relatively shorter than those of S. scherzei, the posterior extremity is broader and the periproct is higher in the steeper posterior truncation (Isralesky, 1924). Schizaster dumblei differs conspicuously from S. costaricensis mainly in the shape of the test, which in S. costaricensis is slender, flatter and diamond-shaped, with the posterior ambulacra almost reaching the ambitus.

The Miocene reports for Schizaster dumblei are uncertain. The previous report of by [START_REF] Israelsky | Notes on some echinoids from the San Rafael and Tuxpam beds of the Tampico Region, México[END_REF] is reported for San Rafael Beds, Tampico Region, Mexico, included in the Meson Formation by [START_REF] Muir | Geology of the Tampico region: Tulsa[END_REF] and dated as Aquitanian, Oligocene, but the Aquitanian is used to be considered Miocene [START_REF] Durham | Miocene echinoids from the Valle Central, Costa Rica[END_REF]. [START_REF] Carreño | Los ostrácodos de edad oligo-miocénica de la subprovincia Tampico-Misantla, área centrooriental de México. Parte I. Oligoceno en Formación Mesón[END_REF] The report of S. dumblei in Jamaica [START_REF] Donovan | Jamaican Cenozoic Echinoidea[END_REF] is uncertain due to differences in the determination of the specimens. [START_REF] Kier | Fossil spatangoid echinoids of Cuba[END_REF] considered the specimens similar to S. subcylindricus; Donovan (1988) regarded the specimens to resemble the holotype of S. brachypetalus (= S. subcylindricus [START_REF] Kier | Fossil spatangoid echinoids of Cuba[END_REF]; finally, Donovan distinguish the specimens of Schizaster "dumbei" by having a more pronounced anterior sulcus than S. subcylindricus, retaining the specimens as Schizaster dumbei? The present report sustains the distribution of S. dumblei during the Miocene in the Caribbean region.

Discussion and conclusions

This is the first report of Stomopneutses pristinus since its description by [START_REF] Jackson | Mexican Fossil Echini[END_REF] from the Oligocene Meson Formation exposed in the Hacienda Tierra Amarilla, Alamo Temapache Municipality, Veracruz, Mexico. The Meson Formation represents a shallow-water depositional environment [START_REF] Barker | Biostratigraphy of some Tertiary formations in the Tampico-Misantla Embayment, Mexico[END_REF], described by [START_REF] Carreño | Los ostrácodos de edad oligo-miocénica de la subprovincia Tampico-Misantla, área centrooriental de México. Parte I. Oligoceno en Formación Mesón[END_REF] as shallow and deep sublittoral, tropical and subtropical. The extant species, Stomopneustes variolaris is restricted to the Pacific Ocean, where it lives in rocky habitats, with a preference for shady areas with constant water circulation, avoiding direct wave action [START_REF] Sastry | Echinodermata associated with coral reefs of Andaman and Nicobar Islands[END_REF]. During the Miocene S. pristinus likely inhabited the reefal high energy environments recorded in the Tulijá Formation. The new report of S. pristinus in Palenque extends the southern range of this species, its chronological distribution into the Miocene, and provides further data on its morphology.

Echinolampas aldrichi has been reported from many Oligocene localities, including

Simojovel Chiapas. There is one possible report of this species in Belize, but the poor preservation quality did not allow the authors to determine it at species level (Donovan et al., 2005a). The present report assures the distribution of E. aldrichi during the Miocene in the Caribbean region. The discovery of E. aldrichi in the Miocene deposits of the Tulijá Formation also complements the understanding of the morphological and taxonomical diversity of this genus in America, particularly in the Caribbean Sea and Gulf of Mexico.

When Clypeaster chiapasensis was first described (Müllerried, 1951), it was based on two specimens, with no data about the precise locality other than "close to Palenque", nor any data of the type series was included. The later description by [START_REF] Caso | El género Clypeaster Lamarck 1801, en el Terciario de México[END_REF] presented discrepancies with the one by Müllerried and was based on two specimens from Chacamax river, but with no catalogue data. The present report establishes a neotype curated in the Coleccion Nacional de Paleontologia, Instituto de Geologia, UNAM and assigns the type locality to the Chacamax river, the same locality reported by [START_REF] Caso | El género Clypeaster Lamarck 1801, en el Terciario de México[END_REF]. The sample size permitted a much more inclusive morphological description.

The presence of Agassizia regia near Palenque is the second report after the initial description from the Oligocene at Tuxpam, on the Gulf of Mexico. This extends its range into the Miocene of the Caribbean region, along with Schizaster dumblei. Based on ostracods [START_REF] Carreño | Los ostrácodos de edad Oligo-Miocénica de la subprovincia Tampico-Misantla, area centrooriental de Mexico. Parte II[END_REF] dated the Tuxpam Formation as Miocene (Burdigalian and possibly upper Aquitanian).

The report in this study of Agassizia regia expands the known distribution from its type area on the Gulf of Mexico to the Caribbean Sea. The large number of specimens, as well as the collections of Schizaster dumblei, permits a thorough description of its morphological range and contributes to the understanding of the morphological and taxonomical diversity of these genera in America, particularly in the Caribbean Sea and Gulf of Mexico.

Genus Echinolampas has world-wide distribution, ranging in age from the Eocene to Recent, so the presence of E. aldrichi does not add much paleoenvironmental information. Nevertheless, the presence of genera Stomopneustes, Clypeaster, Agassizia and Schizaster supports the description of the Tulijá Formation as a shallow marine paleoenvironment.

Here are reported five species belonging to five genera; the table 7 summarizes [START_REF] Cooke | Cenozoic Echinoids of Eastern United States[END_REF]; Tuxpam and Meson Formations, Tampico, Tamaulipas, Mexico [START_REF] Israelsky | Notes on some echinoids from the San Rafael and Tuxpam beds of the Tampico Region, México[END_REF][START_REF] Caso | Los equinoideos fósiles del Cenozoico de México[END_REF];

Chiapas; Belize [START_REF] Donovan | Fossil echinoids from Belize[END_REF]; Costa Rica [START_REF] Jackson | Fossil Echini of the Panama Canal Zone and Costa Rica[END_REF][START_REF] Durham | Miocene echinoids from the Valle Central, Costa Rica[END_REF]; Panama [START_REF] Jackson | Fossil Echini of the Panama Canal Zone and Costa Rica[END_REF]Cooke, 1948); Cuba [START_REF] Jackson | Fossil echini of the West Indies[END_REF][START_REF] Kier | Fossil spatangoid echinoids of Cuba[END_REF]; Puerto Rico [START_REF] Jackson | Fossil echini of the West Indies[END_REF][START_REF] Gordon | Middle Tertiary echinoids from Puerto Rico[END_REF]; Jamaica [START_REF] Donovan | Lower Miocene echinoderms of Jamaica, West Indies[END_REF]; Dominican Republic [START_REF] Jackson | Fossil echini of the West Indies[END_REF]; Guadalupe [START_REF] Jackson | Fossil echini of the West Indies[END_REF].

  , who described E. woodrigni based on Miocene specimens from the Valle Central, Costa Rica, but it is characterized by very narrow petals, almost equally open through their full length. Echinolampas aldrichi differs from the fossil Echinolampas depressa from Tamaulipas, Mexico described by González-Terrazas (2006), mainly in the shape of the petals, which are longer, thinner, and almost straight in E. depressa, with the short line of pores being almost one half of the longer line. E. depressa is ovoid and inflated, while E. aldrichi is wider at the posterior portion of the test, and flat, with the apex coinciding with the apical system. Order Clypeasteroida L. Agassiz, 1835 Family Clypeasteridae L. Agassiz, 1835 Genus Clypeaster Lamarck, 1801 Stratigraphic range-Upper Eocene to Recent (Smith and Kroh, 2011). Diagnosis (sensu Smith and Kroh, 2011)-Clypeaster is characterized by an oral surface flat or concave, generally with an oral infundibulum well developed; ambitus rounded, flat or thick. Apical system and peristome central. Petals are variable, closed and rounded or wide and open; external pores elongated, interior pores rounded, generally joined by well-defined frontal groove. Peripoct inframarginal, sometimes marginal. Buccal membrane naked, with irregular ossicles embedded. Internal supports variable in abundance, forming thin plates or pillars, strongly developed in morphologically flat species. Modern distribution in Mexico-Clypeaster is a diverse genus with numerous species; its modern distribution in Mexican waters includes all the biogeographic regions except the continental slope of the transitional region of the Mexican Pacific Ocean, collected in depths from two to 154 m (Martínez-Melo et al., 2015).

  IGM-loc 3636, El Gato site. Tulijá Formation exposed near the town of Palenque, northern Chiapas. Diagnosis (amended from Caso, 1956)-Test outline oval to subpentagonal. Dorsal surface convex in the petalodium. Apical system slightly anterior. Ambulacral petals open distally. Anterior petal (III) longer than paired petals, posterior pair of petals slightly longer than anterior pair. Oral surface flat, becoming concave at the peristome, with deep ambulacral grooves. Periproct oval, almost round, separated from the margin at the same distance as the diameter of the periproct. Comparative material-Clypeaster antillarum Cotteau, 1875: holotype, USNM PAL 214162 from the Miocene of Anguilla. Clypeaster gatuni Jackson, 1917: holotype, USNM MO 324453 from the Miocene Gatun Formation, Panama. Clypeaster pileus Israelsky, 1924: CAS370 from the Miocene marine deposits of Tampico region, Mexico; IGM 2553, from Miocene deposits of the Mina La Catalina, Simojovel, Chiapas, Mexico. Clypeaster rogersi (Morton, 1834): IGM 2554, from Oligocene deposits along the Río Teapa, Chiapas, Mexico.

  described (IGM 2554) comprises three test fragments that appear to belong to different specimens; the largest specimen presents more inflated petals than C. rogersi. And the paired petals of IGM 2554 are closed distally, while in C. rogersi they are open. Clypeaster chiapasensis differs from C. antillarum Cotteau, 1875, from Miocene deposits of Cuba (Sánchez-Roig, 1926), and C. gatuni Jackson, 1917 from Gatun Formation, Late Miocene (Cadena et al., 2012), Panama Canal Zone. In C. antillarum the test is oval, the apical system is posterior, and the anterior petals are very elongated; on the other hand, the ambitus of C. chiapasensis ranges from rounded to pentagonal, with the anterior petal (III) significantly longer (170%) than the anterior pair of petaloids (II and IV) others. Clypeaster gatuni clearly differs from C. chiapasensis by a more elongated test, with broader petals of obovate shape, wider distally and closing abruptly. Clypeaster chiapasensis has more lanceolate petals, with the maximum width at half the length. Order Spatangoida L. Agassiz, 1840 Family Prenasteridae Lambert, 1905 Genus Agassizia Valenciennes, 1846 Type species-Agassizia scrobiculata Valenciennes in Agassiz and Desor, 1847:20. Stratigraphic range-Middle Eocene to Recent (Smith and Kroh, 2011). Diagnosis (sensu Smith and Kroh, 2011)-Oval test, no anterior sulcus at the ambitus level, apical system ethmolitic, central, with four genital pores. Anterior ambulacrum (III) narrow, with pore-pairs specialized, bearing small penicillate tube-feet, uniserially arranged; anterior paired petals II and IV are longer than posterior I and V, all slightly sunken. Periproct located on the truncated posterior surface. Peristome large, reniform, with short, thin labral plate. Modern distribution in Mexico-On the Pacific coast of northen Mexico, including the eastern coast of the Baja California Peninsula and the Gulf of California (Martínez-Melo et al., 2015).

  Comparative material-Agassizia (Anisaster) mossomi[START_REF] Cooke | Cenozoic Irregular Echinoids of Eastern United States[END_REF]: holotype, USNM MO.498989 1 from Late Oligocene of Florida. Agassizia regia[START_REF] Israelsky | Notes on some echinoids from the San Rafael and Tuxpam beds of the Tampico Region, México[END_REF] holotype, CAS 363.00 from the Tertiary marine deposits of Tuxpam Bed, Tampico Region, Mexico.Remarks-The genus Agassizia is present in the fossil record from the Middle Eocene to Recent (Smith andKroh, 2011). Presently, it is distributed in the North Pacific coast of Mexico, including the west coast of the Baja California Peninsula and the Gulf of California[START_REF] Martínez-Melo | Taxonomía y biogeografía ecológica de los equinoideos irregulares (Echinoidea: Irregularia) de México[END_REF].

  Stratigraphic range-Eocene to Recent (Smith andKroh, 2011).Diagnosis (sensu Smith and Kroh, 2011)-Test outline oval with deep anterior sulcus, slightly pointed at the ambitus. Apical system ethmolithic with four gonopores. Anterior ambulacrum (III) deeply sunken, adapical pairs of pores large and specialized. Periproct small, marginal; peristome reniform, located in anterior third of test; labral plate short and wide, not extending beyond the first half of the first ambulacral plate. Schizaster has well developed lateral and peripetalous fascioles; the peripetalous fasciole indented by three plates behind petals II and IV.

  IGM-Sc1 -IGM-Sc2 from IGM-loc 3636 El Gato site, and IGM-Sc3 from IGM-loc 3880 Río Chacamax site; both from the Miocene Tulijá Formation near Palenque, northern Chiapas, Mexico. Description-Test outline ovoid (length 33-47 mm, width 30-48 mm), ambulacrum III forming deep notch in anterior ambitus; posterior truncated. Test tall (21-31 mm), with adoral and aboral surfaces almost horizontal. Anterior ambulacrum not petaloid, in a notch, with well-developed pore pairs. Paired ambulacra petaloid. Anterior paired petals (II and IV) two times the length of the posterior pair. Anterior paired petals sinuous, opening in an obtuse angle, not reaching the ambitus, with a maximum width at 2/3 length from apical system, with oval pores and a slight furrow connecting the pore pairs. Posterior paired petals lanceolate. Periproct oval, vertical and high on the posterior surface of the test. Peristome anterior, probably labiate. Comparative material-Schizaster (Paraster) sp. aff. lecontei Merriam, 1899: IGM 5920 and IGM 5921, from the lower Eocene of Bateque Formation, Baja California Sur, Mexico. Schizaster dumblei Israelsky, 1924: holotype, CAS 368.00 from Oligocene marine deposits of San Rafael beds, Tampico, Mexico.

  dated Formation Meson as late Oligocene-early Miocene. The Holotype is dated as Oligocene by the California Academy of Sciences (CAS, 2019).

  the taxonomical diversity and fossil record of the five genera during the Miocene along the Caribbean region. With these revisions we start sketching an interesting system between the Caribbean and the Gulf of Mexico basin, connected by the Northern Caribbean Current. Due to the general quality of the fossil record and the scarce revisions on the paleofauna of the region, the present report help fill what has been a major gap in recognizing the distribution of echinoids during the faunal transition from a tropical echinoid fauna characterizing most of the Paleogene to a more temperate fauna characterizing the Neogene as well as the transition between the Caribbean and the Gulf of Mexico basins.

  data (mm) of the specimens of Agassizia regia[START_REF] Israelsky | Notes on some echinoids from the San Rafael and Tuxpam beds of the Tampico Region, México[END_REF] TL, length; TW, width; TH, height; IL, length of petaloid I; IW, width of petaloid I; IIL, length of petaloid II; IIW, width of petaloid II; PsW, width of the peristome; PsL, length of the peristome; PsF, distance from the peristome to the anterior margin; PpW, width of the periproct; PpL, length of the periproct; PpH, height of the periproct.

Figure 2 .

 2 Figure 2. General geologic column of the region and the temporal limits of the stratigraphic units (taken from Martínez-Ortiz et al., 2017).

Figure 3 .

 3 Figure 3. Geologic map of the paleontological sites of the Tulijá Formation that includes echinoid reports. 1, El Gato (IGM-loc 3636); 2, Río Chacamax (IGM-loc 3880); 3, Don Eber (IGM-loc 3879).

Figure 4 .

 4 Figure 4. Stomopneustes pristinus Jackson, 1937. A, Aboral side IGM-S1; B, oral side IGM-S2; C, apical system IGM-S1; D, ambulacral plates at the ambitus IGM-S3; E, interambulacral plates at the ambitus IGM-S4; F, primary spines IGM-S5. amb III, probable ambulacrum III; t, tubercle; pp, pair of pores; al, Aristotle's lantern; m, mamelon; b, boss; mp, madreporite; gp, genital plate; bs, base of spine; sh, shaft.

Figure 5 .

 5 Figure 5. Stomopneustes pristinus Jackson, 1937. Aristotle's lantern IGM-S2. A, picture; B, diagram. h, hemipyramids; e, epiphysis; fm, foramen magnum.

Figure 6 .

 6 Figure 6. Echinolampas aldrichi Twitchell, 1915. A, aboral side; B, oral side; C, lateral side (left); D, posterior side IGM-E1. E, ambulacrum III from the oral side; F, ambulacrum III from the aboral side IGM-E2.

Figure 7 .

 7 Figure 7. Echinolampas aldrichi Twitchell, 1915. A, apical system; B, apical system and ambulacrum V; C, interambulacrum 4; D, tip of ambulacrum III; E, tip of ambulacrum II; F, tip of ambulacrum I.

Figure 8 .

 8 Figure 8. Clypeaster chiapanensis Müllerried, 1951. A, aboral side; B, oral side; C, posterior side; D, lateral side (left) Neotype IGM-C1. E, ambulacrum IGM-C2; F, apical system IGM-C3; G, periproct (oral side) IGM-C4.

Figure 9 .

 9 Figure 9. Agassizia regia Israelsky, 1924. A, aboral side; B, oral side; C, lateral side (left); D, posterior side IGM-A1. E, peristome and plastron IGM-A2; F, apical system IGM-A3; G, ambulacrum I IGM-A4; H, ambulacrum II IGM-A5. ps, peristome; pp, pair of pores; gp, genital pores; ap, atrophied plates in ambulacrum II.

Figure 10 .

 10 Figure10. Schizaster dumblei[START_REF] Israelsky | Notes on some echinoids from the San Rafael and Tuxpam beds of the Tampico Region, México[END_REF]. A, aboral side; B, oral side; C, posterior side; D, lateral side (left) IGM-Sc2. E, peristome and plastron; F, apical system and posterior ambulacra (I and V); G, peristome; H, periproct; I, ambulacrum II. pl, plastron; p, periproct; as, apical system; pp, pair of pores in ambulacrum II IGM-Sc3.

Table 1 .

 1 Paleontological sites near Palenque, Chiapas, where the fossil echinoids referred in this work were collected, (also see Figure2).

	Tables
	Paleontological	IGM-loc	Geographical coordinates
	sites			N-W
	Don Eber site	3879 17°29'29.7"-92°3'46.2"
	Río Chacamax	3880 17°28'49.93"-91°58'28.64"
	El Gato 3		3636 17°29'29.4"-92°56'29.5"
	El Gato 2		3636 17°29'59.4"-92°56'30.7"
	El Gato 1		3636 17°29'21.9"-92°56'33.1"
		Diameter Ambulacrum Interambulacrum
	IGM-S1	63.77	13.33	22.86
	IGM-S2	105.47	20.28	44.19
	IGM-S3	84.21	18.94	34.65
	IGM-S4	89.53	16.21	34.15
	IGM-S5	57.73	11.43	21.86
	IGM-S6	60.03	12.71	21.05
	IGM-S7	87.61	18.23	33.31
	IGM-S8	96.62	17.71	33.51
	IGM-S9	92.51
	IGM-
	S10	98.63	19.51	35.16
	IGM-			22.86	38.72

Table 2 .

 2 Morphometric data (mm) of the specimens of Stomopneustes pristinus[START_REF] Jackson | Mexican Fossil Echini[END_REF]. Ambulacra and interambulacra measured at the ambitus.

	TL	TW	TH	IL	IW IIL	IIW	IIIL	IIIW	PsW PsL PsF	PpW PpL PpB
	IGM-E1 79.66 75.4 33.91		38.38 11.4 33.74/27.75 10.63 31.21/28.17	9.15 11.09 7.28 31.18 12.64	0.63
	IGM-E2 69.57 70.72 35.73		37.2 9.86	8.67	28.9 33.87/28.35		14.03 5.03 1.33
	IGM-E3 69.74 61.85 26.3 27.32/25.41 8.84 24.55/22.5	8.24 24.91/23.73	7.51 11.68 3.6 31.96 11.91 7.54 1.92
	IGM-E4 68.13 61.98		31.64/29.01 8.71 24.18/19.6	7.84	22.84	6.97
	IGM-E5 74.43 71.04 28.32		36.88 9.65 32.00/25.57	8.27 28.46/27.61	6.77	31.1

Table 3 .

 3 Morphometric data of the specimens of Echinolampas aldrichi Twitchell,

	1915. TL, length; TW, width; TH, height; IL, length of petaloid I; IW, width of petaloid
	I; IIL, length of petaloid II; IIW, width of petaloid II; IIIL, length of petaloid III; IIIW,
	width of petaloid III; PsW, width of the peristome; PsL, length of the peristome; PsF,
	distance from the peristome to the anterior margin; PpW, width of the periproct; PpL,
	length of the periproct; PpB, distance from the periproct to the posterior margin.

Table 4 .

 4 Morphometric data (mm) of the specimens of Clypeaster chiapasensisMüllerried, 1951. There are not data of the peristome because there were no one visible. TL, length; TW, width; TH, height; IL, length of petaloid I; IW, width of petaloid I; IIL, length of petaloid II; IIW, width of petaloid II; IIIL, length of petaloid III; IIIW, width of petaloid III; PpW, width of the periproct; PpL, length of the periproct; PpB, distance from the periproct to the posterior margin.

Table 6 .

 6 Morphometric data (mm) of the specimens of Schizaster dumblei Israelsky, 1924. TL, length; TW, width; TH, height; IL, length of petaloid I; IW, width of petaloid I; IIL, length of petaloid II; IIW, width of petaloid II; IIIL, length of petaloid III; IIIW, width of petaloid III; PsW, width of the peristome; PsL, length of the peristome; PsF, Figures Figure 1. Previous reports of Miocene faunas. The Intracoastal Waterway Canal in Horry County, South Carolina, United States of America

		E.
		woodringi Durham,		X
		1966
	Clypeaster	C. 1922 caudatus Jackson,			X
		C.
		chiapasensi
		s		X
		Müllerried,
		1951
		C.
		concavus Cotteau,	X	X	X
		1866
		C.
		concavus
		puertorican		X	X
		us Gordon,
		1963
		C.
		crustulum Michelin,		X
		1855
		C. cubensis
		Cotteau,		(?) X
		1875
		C. dalli
		Twitchell,			(?)
		1915
		C. gatuni
		Jackson,		X
		1917
		C.
		marinanus Jackson,	X	( ?)
		1937
		C. meridanens is		X	X
		Michelin,

Acknowledgements

To Martha Cuevas-García, Jesús Alvarado-Ortega and their students, whose effort allowed the recovery of the fossils studied in this manuscript. To Susana Guzman for her help with the multifocal microscopy, as well as Kleyton Cantalice and Juan Miguel Contreras for taking the photographs that illustrate this study. Violeta Romero kindly allowed access to the Colección Nacional de Paleontología of UNAM and the review of the type specimens referenced here. To Jesus Alvarado and Loïc Villier for kindly reviewing this manuscript.

Funding

This work was supported by the DGAPA-PAPIIT projects IN 207314 and IN209017; the INAH project "Estudio arqueológico y paleontológico de los fósiles marinos que proceden del sitio de Palenque, Chiapas". Additionally, the author was supported by the CONACYT EPE fellowship and a UNAM-DGAPA Postdoctoral fellowships.

Declaration of interest

None distance from the peristome to the anterior margin; PpW, width of the periproct; PpL, length of the periproct.

Table 7. Species of genus Echinolampas, Clypeaster, Agassizia, Schizaster reported from the Miocene in the Caribbean Region. Eastern USA [START_REF] Cooke | Cenozoic Echinoids of Eastern United States[END_REF]; Gulf of Mexico [START_REF] Israelsky | Notes on some echinoids from the San Rafael and Tuxpam beds of the Tampico Region, México[END_REF][START_REF] Caso | Los equinoideos fósiles del Cenozoico de México[END_REF]; Chiapas; Belize [START_REF] Donovan | Fossil echinoids from Belize[END_REF]; Costa Rica [START_REF] Jackson | Fossil Echini of the Panama Canal Zone and Costa Rica[END_REF][START_REF] Durham | Miocene echinoids from the Valle Central, Costa Rica[END_REF]; Panama [START_REF] Jackson | Fossil Echini of the Panama Canal Zone and Costa Rica[END_REF]Cooke, 1948); Cuba [START_REF] Jackson | Fossil echini of the West Indies[END_REF][START_REF] Kier | Fossil spatangoid echinoids of Cuba[END_REF]; Puerto Rico [START_REF] Jackson | Fossil echini of the West Indies[END_REF][START_REF] Gordon | Middle Tertiary echinoids from Puerto Rico[END_REF]; Jamaica [START_REF] Donovan | Lower Miocene echinoderms of Jamaica, West Indies[END_REF]; Dominican Republic [START_REF] Jackson | Fossil echini of the West Indies[END_REF]; Guadalupe [START_REF] Jackson | Fossil echini of the West Indies[END_REF]. (?): The locality could not be from the Miocene. These records are taken from catalogues that sometimes do not show the complete information about the localities of collect for each species, allowing the comparison at country level.

Easte


MD Ghassen Cheniti

PhD Stephane Puyo

MD Claire A Martin

MD Antonio Frontera

MD Konstantinos Vlachos

MD Masateru Takigawa

MD Felix Bourier

MD Takeshi Kitamura

MD Anna Lam

PhD Carole Dumas-Pommier

PhD Xavier Pillois

MD Thomas Pambrun

MD Josselin Duchateau

MD Nicolas Klotz

MD Arnaud Denis

MD Nicolas Derval

MD Hubert Cochet

MD Frederic Sacher

PhD Remi Dubois

MD Pierre Jais

MD Meleze Hocini

MD Michel Haissaguerre

Noninvasive Mapping and Electrocardiographic Imaging in Atrial and Ventricular Arrhythmias (CardioInsight)

à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction:

Electrocardiographic imaging (ECGI) is a mapping technique aiming to non-invasively characterize cardiac electrical activity. This approach uses signals collected from the torso to reconstruct epicardial potentials. Its efficacy has been demonstrated in a wide variety of clinical scenarios ranging from the mapping of premature ventricular complexes (PVCs) and accessory pathways to the mapping of complex arrhythmias including atrial and ventricular fibrillation [START_REF] Shah | Non-invasive Mapping of Cardiac Arrhythmias[END_REF][START_REF] Frontera | Frontiers in non-invasive cardiac mapping: future implications for arrhythmia treatment[END_REF]. This approach allows guidance of catheter ablation and offers a unique opportunity to better understand the mechanism of cardiac arrhythmias. We review in this chapter the basics of ECGI, the different fields where it has proven efficient and finally discuss the limitations of this approach.

Principles of non-invasive mapping

Research related to non-invasive mapping commenced several decades ago, involving purely analytical studies [START_REF] Rudy | The effects of variations in conductivity and geometrical parameters on the electrocardiogram, using an eccentric spheres model[END_REF][START_REF] Figuera | Regularization Techniques for ECG Imaging during Atrial Fibrillation: A Computational Study[END_REF][START_REF] Svehlikova | Geometrical constraint of sources in noninvasive localization of premature ventricular contractions[END_REF], torso tank [START_REF] Oster | Noninvasive electrocardiographic imaging: reconstruction of epicardial potentials, electrograms, and isochrones and localization of single and multiple electrocardiac events[END_REF][START_REF] Oster | Electrocardiographic imaging: Noninvasive characterization of intramural myocardial activation from inverse-reconstructed epicardial potentials and electrograms[END_REF][START_REF] Shome | Simultaneous High-Resolution Electrical Imaging of Endocardial, Epicardial and Torso-Tank Surfaces Under Varying Cardiac Metabolic Load and Coronary Flow[END_REF][START_REF] Ramanathan | Electrocardiographic imaging: II. Effect of torso inhomogeneities on noninvasive reconstruction of epicardial potentials, electrograms, and isochrones[END_REF][START_REF] Bear | Cardiac electrical dyssynchrony is accurately detected by noninvasive electrocardiographic imaging[END_REF] and large animal models [START_REF] Liu | Noninvasive mapping of transmural potentials during activation in swine hearts from body surface electrocardiograms[END_REF][START_REF] Cluitmans | In Vivo Validation of Electrocardiographic Imaging[END_REF][START_REF] Bear | How Accurate Is Inverse Electrocardiographic Mapping? A Systematic In Vivo Evaluation[END_REF], followed by application in humans [START_REF] Ghanem | Noninvasive electrocardiographic imaging (ECGI): comparison to intraoperative mapping in patients[END_REF][START_REF] Haissaguerre | Driver domains in persistent atrial fibrillation[END_REF][START_REF] Haissaguerre | Localized Structural Alterations Underlying a Subset of Unexplained Sudden Cardiac Death[END_REF]. Mathematically, ECGI solves the inverse problem of electrocardiography that aims to locate on the epicardium the source of a signal recorded on the torso [START_REF] Cluitmans | Validation and Opportunities of Electrocardiographic Imaging: From Technical Achievements to Clinical Applications[END_REF][START_REF] Rudy | The inverse problem in electrocardiography: solutions in terms of epicardial potentials[END_REF][START_REF] Barr | Relating epicardial to body surface potential distributions by means of transfer coefficients based on geometry measurements[END_REF]. Briefly, a 252-electrode vest is applied to the patient's torso and connected to the system (ECVue, Cardioinsight Technologies Inc, Cleveland, OH). A high-resolution non-contrast computed tomography (CT) scan is then performed, allowing the definition of cardiac anatomy and the position of each electrode on the torso. Atrial and/or ventricular geometry are then reconstructed to obtain a three-dimensional (3D) mesh. This model serves for the projection of unipolar signals represented by virtual nodes of the epicardial surface. The collected signals are post processed using mathematical reconstruction algorithms [START_REF] Messinger-Rapport | The Inverse Problem in Electrocardiography: A Model Study of the Effects of Geometry and Conductivity Parameters on the Reconstruction of Epicardial Potentials[END_REF][START_REF] Ramanathan | Noninvasive electrocardiographic imaging for cardiac electrophysiology and arrhythmia[END_REF] to create different maps, including activation maps, voltage maps, isopotential maps and phase maps. Activation maps are computed using intrinsic deflection-based methods from unipolar electrograms (maximal dV/dT). Phase is calculated at each node using a dedicated Hilbert transform. The system uses reconstructed signals to calculate the phase of each signal ranging between -π and π. The intersection between the depolarization and the repolarization isolines defines phase singularities [START_REF] Gray | Spatial and temporal organization during cardiac fibrillation[END_REF]. Phase mapping allows identification of focal breakthrough, where activation starts from a discrete point and has a centrifugal spread, and reentry, where a wavefront rotates on itself within a localized area. It is important to note that ECGI uses a standardized workflow (Figure 1) where each step is critical for the following ones. It is essential to ensure optimal workflow to acquire accurate results.

Atrial arrhythmias

 Atrial fibrillation

Recent research has demonstrated that atrial fibrillation (AF) is mainly driven by localized sources, including focal and anatomical or functional reentries [START_REF] Cheniti | Atrial Fibrillation Mechanisms and Implications for Catheter Ablation[END_REF]. These sources are typically unstable and dynamic, which dramatically affects the results of point by point The effects of antiarrhythmic drugs were assessed in a group of 13 patients who underwent ablation for PsAF [START_REF] Amraoui | 209-05: Does flecainide pre-treatment helps to identify the most important players?[END_REF]. ECGI recordings were acquired before and after infusion of flecainide. Flecainide infusion reduced the number of regions that hosted reentrant activity (from 7 to 4 regions, p< 0.001). Importantly, AF terminated to sinus rhythm in 11 cases, involving targeting the regions remaining after flecainide infusion in 9/11 cases. This result suggests that anti arrhythmic drugs select more stable and important regions that sustain AF. Similarly, amiodarone was used in patients with structural heart disease and PsAF, and resulted in AF termination with a shorter duration of radiofrequency [START_REF] Cheniti | 216-28: Electrophysiological effects of amiodarone in patients with persistent atrial fibrillation[END_REF]. In our practice, an antiarrhythmic drug is used before ablation for PsAF in order to limit the effects of the electrical remodeling.  Atrial tachycardia  ECGI can locate the source of focal atrial tachycardias (ATs). Wang et al [START_REF] Wang | Focal atrial tachycardia after pulmonary vein isolation: noninvasive mapping with electrocardiographic imaging (ECGI)[END_REF] successfully used ECGI to locate the origin of a left focal AT close to the septum. The site was confirmed by invasive mapping by recording diastolic potentials 58ms before the onset of the P wave. Local ablation terminated the tachycardia. Several more cases have reported the usefulness of ECGI in patients with focal atrial tachycardias [START_REF] Yamashita | High-density contact and noninvasive mapping of focal atrial tachycardia: Evidence of dual endocardial exits from an epicardial focus[END_REF].  In addition, ECGI can also help characterize macroreentrant AT. Wang et al [START_REF] Wang | Noninvasive electrocardiographic imaging (ECGI) of scar-related atypical atrial flutter[END_REF] used ECGI to characterize an atypical flutter that developed in a patient with a previous COX-MAZE surgical procedure.  Shah et al. [START_REF] Shah | Validation of novel 3-dimensional electrocardiographic mapping of atrial tachycardias by invasive mapping and ablation: a multicenter study[END_REF] A dominant ventricle, hosting more than 50% of activities, was identified in 9 patients while the rest demonstrated biventricular distribution of the fibrillatory activities (Figure 4). Abnormal electrograms lasting ≥70ms and ≥3 spikes were seen in 15/24 patients (62.5%). These electrograms were predominantly located on the epicardium of the right ventricle; they were arranged in a confluent pattern and covered a limited surface area (13 ± 6 cm2), representing 5 ± 3% of the total ventricular surface area. They colocated with the driver regions in 76% of cases (p < 0.001) (Figure 5). The 9 patients without structural alterations had a high incidence of Purkinje triggers (7/9

 Premature Ventricular Complexes (PVCs) and ventricular tachycardia (VT)

 ECGI has proven to be efficient in locating the origin of PVCs [START_REF] Jamil-Copley | Noninvasive electrocardiographic mapping to guide ablation of outflow tract ventricular arrhythmias[END_REF][START_REF] Cakulev | Confirmation of novel noninvasive high-density electrocardiographic mapping with electrophysiology study: implications for therapy[END_REF]. This role is particularly useful in patients with infrequent or transient PVCs and allows optimal scheduling of the procedure (Figure 6 and7)  Cakulev et al [START_REF] Cakulev | Confirmation of novel noninvasive high-density electrocardiographic mapping with electrophysiology study: implications for therapy[END_REF] 8). Gosh et al [START_REF] Ghosh | Cardiac memory in patients with Wolff-Parkinson-White syndrome: noninvasive imaging of activation and repolarization before and after catheter ablation[END_REF] used ECGI to map 14 patients with a Wolff Parkinson White syndrome. All AP locations were correctly identified by ECGI, corresponding to the site of successful ablation. AP were left lateral in 5 cases, posteroseptal in 4 case, right posteroseptal in 2 cases, mid septal in 1 case, right posterior in 1 case and epicardial within a coronary sinus diverticulum in 1 case. Gosh et al. also reported successful AP ablation guided by ECGI in patients with structural heard disease, including congenital heart disease with univentricular heart [START_REF] Ghosh | Noninvasive electrocardiographic imaging (ECGI) of a univentricular heart with Wolff-Parkinson-White syndrome[END_REF], hypertrophic cardiomyopathy [START_REF] Ghosh | Hypertrophic cardiomyopathy with preexcitation: insights from noninvasive electrocardiographic imaging (ECGI) and catheter mapping[END_REF] and Ebstein anomaly [START_REF] Ghosh | Noninvasive electrocardiographic imaging (ECGI) of epicardial activation before and after catheter ablation of the accessory pathway in a patient with Ebstein anomaly[END_REF]. Data from our laboratory (47) reported a patient with a right malignant accessory pathway and multiple failed ablation procedures. The combination of ECGI and high resolution CT scan identified a right atrial diverticulum where the AP was located and facilitated catheter ablation.

Limitations of ECGI

Non-invasive mapping has some limitations that should be considered to obtain optimal results. Cardiac signals are attenuated while crossing the thorax, leading to "blurred vision" by the recording electrode on the torso. Subsequently, the recorded signals by each electrode on the torso represent the average of multiple signals. ECGI solves the inverse problem in electrocardiography [START_REF] Rudy | Noninvasive electrocardiographic imaging of arrhythmogenic substrates in humans[END_REF][START_REF] Tikhonov | Solution of Ill-Posed Problems[END_REF], but this may lead to even small errors in the signals measured on the torso (measurement noise, electrode position...) resulting in very large errors in the reconstruction of the epicardial signals.

Performing activation mapping may have limitations that are demonstrated in a recent study performed by Duchateau et al [START_REF] Duchateau | Performance and limitations of noninvasive cardiac activation mapping[END_REF]. The authors evaluated the accuracy of activation maps acquired by automatic processing of the system in 55 patients and compared them to epicardial maps collected in the same patients. They concluded that the correlation between ECGI and invasive epicardial mapping was poor, as attested by the recording of fewer epicardial breakthroughs and the creation of false epicardial lines of block in areas of low voltages. Remapping, performed manually thereafter, successfully identified the epicardial breakthroughs with a mean > 2 breakthroughs per patient. In addition, areas with low voltage and septal signals represent a major limitation of this mapping technique and should be analyzed with caution. However, the correlation between ECGI and invasive mapping was good in patients with a wide QRS, either paced or due to bundle branch block. This technique can therefore be used for better selection of candidates for cardiac resynchronization [START_REF] Ploux | Noninvasive electrocardiographic mapping to improve patient selection for cardiac resynchronization therapy: beyond QRS duration and left bundle branch block morphology[END_REF].

Phase mapping have some limitations [START_REF] Umapathy | Phase mapping of cardiac fibrillation[END_REF][START_REF] Nair | Intramural activation during early human ventricular fibrillation[END_REF]. First, this technique uses reconstructed signals which should be of good quality for better calculation. The presence of noise may induce some errors during the reconstruction. It is important to note that reentrant activities identified by the system do not preclude the presence of a "rotor", as has been electrophysiologically described by optical mapping [START_REF] Pandit | Rotors and the dynamics of cardiac fibrillation[END_REF]. It identifies areas of complex activity surrounded by signal covering all the arrhythmia cycle length, suggesting the presence of a reentrant activity without specifying its mechanism (Figure 9). To overcome these problems, local signals are checked manually to demonstrate the presence of a QS pattern for focal breakthrough and the presence of signals covering all the arrhythmia cycle length for reentrant activities.

Conclusion

ECGI is a non-invasive mapping technique that has been proven efficient in treating and understanding the mechanisms of a wide variety of atrial and ventricular arrhythmias. An optimal workflow is mandatory to obtain optimal results. Signals recorded by the system and included in the calculation should be checked manually to avoid some errors related to automatic processing. Signals of good quality and high amplitude provide maps with the highest accuracy. Further research aiming to record signals of high quality, better understand cardiac activation (eg, septal activation, Purkinje fiber activation), better correlate the maps to the underlying mechanism can improve the accuracy of ECGI.

Figure 1 :Figure 2 :Figure 3 :

 123 Figure 1: ECGI workflow. A 252-electrode vest is applied to the patient's torso (A). A highresolution non-contrast computed tomography scan is then performed (B), allowing the definition of cardiac anatomy (C) and the position of each electrode on the torso (D). The collected signals are post processed using mathematical reconstruction algorithms (E-F) and projected on the cardiac surface (G)

Figure 4 :Figure 5 :Figure 6 :

 456 Figure 4: Non-invasive mapping in a 59-year-old woman with recurrent idiopathic ventricular fibrillation (VF) showing the dominant role of the left ventricle. A: Normal 12 lead ECG. B: VF induced by programmed ventricular stimulation from the right ventricle (RV). C: Phase mapping identifies a cluster of reentrant activity located at the infero-basal left ventricular wall. This area was consistently identified in two episodes of VF and was targeted by endocardial ablation with a good outcome. LAD: Left anterior descending. (From Frontera A, Cheniti G, Martin CA, Takigawa M, Duchateau J, Puyo S, et al. Frontiers in noninvasive cardiac mapping: future implications for arrhythmia treatment. Minerva cardioangiologica. 2018;66(1):75-82; with permission.)

Figure 7 :

 7 Figure 7: Twelve lead ECG and activation maps of spontaneous premature ventricular complexes (PVCs) in a 30 year old. male. PVCs. The PVC initiating ventricular fibrillation (VF) has a similar morphology (right map) as the previous PVC (left map) with subtle changes in the precordial leads (V2-V3). The PVC initiating VF is located at the anteroapical right ventricle (white star) that was targeted by ablation. LAD: Left anterior descending.

Figure 8 :

 8 Figure 8: Twelve lead ECG (A) showing a posteroseptal pathway. Mapping of the delta wave (B) locates the ventricular insertion at the base of the interventricular septum (C). Local signals show a QS pattern with an early local activation (D).

Figure 9 :

 9 Figure 9: Electrograms at the sites of reentrant activities show complex activities while signals in the remaining atria are organized. Right atrial signals are checked manually, confirming the presence of a local reentry with signals covering all atrial fibrillation cycle lengths. LA, left atrium; LAA, left atrial appendage; LIPV, left inferior pulmonary vein; LSPV, left superior pulmonary vein; RA, right atrium; RIPV, right inferior pulmonary vein; RSPV, right superior pulmonary vein. (From Cheniti G, Vlachos K, Pambrun T, Hooks D, Frontera A, Takigawa M, et al. Atrial Fibrillation Mechanisms and Implications for Catheter Ablation. Front Physiol. 2018;9:1458; with permission.)

  mapping.  Particularities of non-invasive mapping during AF Atrial signals are of lower amplitude compared to ventricular signals. During AF, they are collected between the end of the T wave and the beginning of QRS. Pauses exceeding 1000ms are included in the analysis. The number of windows can be chosen at operator discretion. This analysis can be performed before the procedure. Intravenous diltiazem is infused in patients with rapid ventricular rates, in the absence of left ventricular dysfunction. Cumulative maps are used to locate the areas of focal breakthrough and reentrant drivers.  Results of non-invasive mapping Cuculich et al. (24) first used ECGI to evaluate the mechanisms and complexity of AF in 26 patients. The authors analyzed paroxysmal and persistent AF episodes.

	The spatial accuracy for determining different pacing sites was 6 ± 4 mm.
	Multiple wavelets (defined as contiguous areas of epicardial activation lasting ≥5
	ms) were the most predominant pattern, representing 92% of fibrillatory activity.
	Rotor activity was present in 15% of cases, only in patients with non-paroxysmal
	AF. The authors defined a complexity index as the sum of the number of wavelets
	and focal activities and showed an increased complexity correlating with duration
	of AF (Figure 2)
	Data from our laboratory (15) reported the results of 103 patients with persistent
	AF (PsAF). Analysis of cumulative windows of 9 ± 1 s of AF was performed using
	phase mapping. Focal and reentrant activities were the main mechanisms
	identified by ECGI. AF complexity increased with AF duration, being driven by two
	to three regions during the first months and becoming bi-atrial in PsAF of longer
	duration. Reentrant drivers were located in the pulmonary vein (PV) antra and
	surrounding structures, the left atrial appendage and septum in nearly all the
	cases. Focal breakthroughs arose predominantly from the PV ostia and left and
	right appendages.
	In the prospective AFACART study (25), ECGI was used to guide ablation in 118
	patients with PsAF lasting <1 year. Reentrant activities were recorded in all
	patients and were more frequently located around the PVs, at the anterior
	interatrial groove and the posterior and inferior left atrium. Focal breakthroughs
	were mapped in 95% of the cases and were more commonly located in the PVs
	and both appendages. Ablation strategy consisted in targeting driver areas
	identified by ECGI, followed by pulPV isolation and finally by linear ablation if the
	AF persisted. Driver-only ablation resulted in AF termination in 64% of cases after
	a mean radiofrequency time of 46 ± 26 min; additional PVI and left atrial lines
	increased the success rate to 72%.
	Lim et al (26) prospectively recruited 105 consecutive patients referred for
	ablation of PsAF, including 32 patients in sinus rhythm, 45 patients with AF
	duration <12months and 28 patients in AF for >12months. Phase mapping was
	used to characterize the AF complexity in each group. AF complexity significantly
	increased between the different groups, as attested by an increase in the number
	of reentries and focal activities and the number of regions harboring reentrant
	activities. ECGI guided AF termination was 70%, being lowest in patients with
	longest AF duration.

Figure 3)

  the definition of areas with abnormal epicardial signals during sinus rhythm, and the analysis of each VF episode using windows of different durations chosen at operator discretion. All abnormal signals and areas of interest identified by the system are checked during extensive biventricular and epicardial invasive mapping.

	o Mapping and ablation of idiopathic VF (IVF)
	In a recent study, Haissaguerre et al (16) demonstrated that almost 2/3 of
	patients with IVF have subclinical localized structural alterations. The
	authors evaluated 24 patients (mean age 29 years) who survived IVF. They
	characterized VF drivers during the initial 5 seconds of spontaneous or
	induced VF. In addition, they performed high density endocardial and
	epicardial biventricular mapping during sinus rhythm to identify
	subclinical substrates focusing on VF driver areas. A decapolar catheter
	was used to map the endocardium of the right and left ventricles, while
	20-pole catheters with 2mm inter-electrode spacing (Pentaray,
	BiosenseWebster, CA; Lasso, BiosenseWebster, CA) were used for
	biventricular epicardial mapping.
	A total of 19 VF episodes were analyzed. The mean VF cycle length was
	183 ± 23ms including 28 ± 3 VF cycles. A mean of 2.8 ± 0.7 activities
	(including focal and reentrant activities) were recorded per cycle, being
	reentrant in 87% and focal in 13%.
	Ventricular arrhythmias
	 Ventricular fibrillation
	VF is a major a cause of sudden death that may result from a range of cardiac
	diseases. Patients who survive after sudden cardiac death (SCD) remain at high
	risk of ventricular fibrillation (VF) recurrence and of implantable cardioverter
	defibrillator shocks. Identifying the VF triggers and substrate and the sources that
	maintain VF offers a unique opportunity to better understand this fatal
	arrhythmia and prevent its recurrence.

performed a multicenter prospective study to evaluate ECGI in 52 patients who presented with spontaneous or post AF ablation ATs. ECGI correctly identified the mechanism of AT in 92% of the cases, including 85% of macroreentries and 100% of focal ATs. For macroreentrant AT, ECGI was most accurate in diagnosing peri-tricuspid and roof dependent flutters; however, only 20% of peri-mitral flutters were successfully identified.  In a recent study (HRS abstract C-AB32-04), Kitamura et al.

mapped

7 AT using high-density mapping (Rhythmia, Boston Scientific) and ECGI. Activation mapping identified 2 focal ATs, 1 localized reentry and 4 macroreentries. ECGI correctly identified the mechanism of AT in 6/7 ATs. The accuracy was the highest for focal ATs. (o Particularities of mapping during VF Ventricular signals have a higher amplitude than atrial signals. In our experience, signals recorded during VF are frequently of good quality, allowing accurate post processing. We perform a separate analysis for each VF episode. This includes systematic mapping of spontaneous PVCs initiating VF,

  The ER pattern was present in the inferolateral leads in 8 patients and only in the inferior leads in 23 patients. A Brugada pattern was also present in 23 patients. The authors identified low voltage areas with fractionated signals in 22/23 patients with BS and ER patterns. These signals were epicardial and were recorded on the right ventricular outflow tract (RVOT) and inferior right ventricle (RV), and co-localized with VF drivers identified by ECGI.

	). o J wave syndromes J wave syndromes include early repolarization syndrome (ERS) and Brugada syndrome (BS). Both conditions are associated with a higher vulnerability to ventricular arrhythmias and SCD and can coexist in the same patient.  Early repolarization syndrome (ERS) ERS is defined as an ER pattern (33) (J point elevation ≥ 1mm in 2 contiguous inferior and/or lateral leads of a 12-lead ECG) and (1) a patient who has survived a SCD or (2) a SCD with a negative autopsy and medical chart review with a previous ECG. Nademanee and al. (HRS 2018) performed high density biventricular endocardial and epicardial mapping in 31 patients with ERS and a history of frequent VF episodes (between 2 and while patients without structural alterations underwent ablation of Purkinje triggers. Ablation prevented VF induction in 81% of the cases and was associated with VF freedom in 90% of cases after a median follow-up of 37 months. This study allowed identification of two mechanisms underlying the J wave syndromes (34). The first one consists of delayed depolarization of the inferior RV that is predominantly found in the presence of concomitant BS and ERS. The second mechanism is a repolarization abnormality, either delayed repolarization (24%) or early repolarization (76%), that is mainly encountered in the absence of BS.  Brugada syndrome Nademanee et al (35, 36) first described the presence of epicardial substrate located on the RVOT. The authors recorded areas with low voltage, involving fragmented late potentials (96 ms +/-47ms beyond QRS) with long duration (132 +/-48ms) in 9 symptomatic patients with type 1 BS. Zhang et al (37, 38) used ECGI in 25 patients to characterize the substrate underlying BS in 25 patients with BS. The authors recorded delayed activation of the RVOT, where unipolar signals were fractionated and had a lower amplitude. In a recent study, Hocini et al (HRS 2017) analyzed VF drivers during 34 VF episodes that were recorded in 25 patients with BS. The mean number of VF episodes before ablation was 9 +/-10. The right ventricle was dominant during the initial phase of VF in 76% of cases. VF drivers were mainly represented by focal breakthrough and figure of eight reentries. RV drivers were predominant for 4.6 +/-3.2s, after which VF drivers become biventricular. Endocardial and epicardial mapping recorded abnormal potentials located at the RVOT and the anterior RV in 17 cases. Ablation of the substrate was associated with VF freedom in 150 VFs). Ablation targeting abnormal areas was performed in this group, 15/17 patients after 14-months of follow-up.

Substrate characterization in patients with adult congenital heart diseases (ACHD)

  used ECGi in 27 patients, including 10 patients with PVCs and 1 patient with focal VT. ECGI correctly located the origin of the arrhythmia in 9/11 cases and resulted in arrhythmia suppression in 2 patients that underwent ECGI guided ablation alone in the absence of spontaneous PVCs during the case.  Intini et al.[START_REF] Intini | Electrocardiographic imaging (ECGI), a novel diagnostic modality used for mapping of focal left ventricular tachycardia in a young athlete[END_REF] first used ECGI to guide diagnosis and therapy of a focal VT in a young athlete. ECGI was used before the invasive procedure and correctly identified the origin of the VT that arose from a left ventricular apical diverticulum. Local unipolar signals at the site of origin showed a QS pattern consistent with an epicardial exit.  Jamil-Copley et al. (39) recruited 24 patients with outflow tract PVCs. ECGI correctly identified the origin of the PVCs in 23/24 patients (RVOT= 18, LVOT=8) and sublocalized the origin of the PVCs in all cases.  Patients with ACHD disease are at risk of atrial and ventricular arrhythmias. The complex anatomy and substrate in such patients represents a limitation to invasive mapping. Ernst et al (42) used ECGI in 14 patients withACHD disease (mean age 37 +/-18 years) to document clinical arrhythmia, inducible or spontaneously occurring, prior to invasive ablation. The underlying structural disease ranged from left atrial isomerism to tricuspid atresia with Fontan operation, aortic coarctation and atrial switch for d-transposition of great vessels. The majority of the patients had at least one failed sequential electrophysiological study. ECGI correctly identified the chamber of origin in all cases, being the atria in 6 cases and the ventricles in 7 cases. One patient was excluded because no arrhythmia was recorded. ECGI facilitated ablation by showing the mechanism of the arrhythmia and by guiding ablation. This role was particularly interesting in patients with multiple arrhythmias and complex anatomy. After a median follow-up of 18 months, 64% of the patients remained in sinus rhythm.

 Ventricular preexcitation ECGI can accurately locate accessory pathways (AP) (Figure