Keywords: Phylogeny, Neogastropoda, Mitriform gastropods, Mitridae, Costellariidae, Ptychatractidae, Volutomitridae, Mitra, Vexillum, radula, marine molluscs

With about 800 Recent species, "miters" are a widely distributed group of tropical and subtropical gastropods that are most diverse in the Indo-West Pacific. They include the two families Mitridae and Costellariidae, similar in shell morphology and traditionally treated as close relatives. Beside, some genera of deep water Ptychatractidae and Volutomitridae are close to miters in shell morphology, and the term "mitriform gastropods" has been introduced to refer to Mitridae, Costellariidae and this assortment of convergent forms. The present study aims at reconstruction of phylogenetic relationships of mitriform gastropods based on representative taxon sampling. Four genetic markers (COI, 16S rRNA, 12S rRNA and H3) were sequenced for over 90 species in 20 genera, and the molecular dataset was supplemented by studies of radula morphology. Our analysis recovered Mitridae as a monophyletic group, while the genus Mitra is found polyphyletic. Of 42 mitrid species included in the analysis, 37 formed a well supported "core Mitridae" consisting of four major clades, three of them consistent with the subfamilies Cylindromitrinae, Imbricariinae, and Mitrinae, and Strigatella paupercula standing out by itself. Basal to the "core Mitridae" are four minor lineages, with the genus Charitodoron recognized as sister group to all other Mitridae. The deep water family Pyramimitridae shows a sister relationship to the Mitridae, with high support for a Pyramimitridae + Mitridae clade. Our results recover the monophyly of the Costellariidae, which form a well supported clade that also includes Ptychatractidae, Columbariinae and Volutomitridae, but not Mitridae. Most derived and diverse among Costellariidae are species of Vexillum, characterized by a bow-shaped, multicuspidate rachidian tooth. Several previously unrecognized deep water costellariid lineages are revealed. Their members retain some plesiomorphies -in particular a tricuspidate rachidian tooth -that makes them morphologically intermediate between ptychatractids and Vexillum. The taxa of Ptychatractidae included in the analysis are not monophyletic, but form three well supported, unrelated, groupings, corresponding respectively to Ceratoxancus + Latiromitra, Exilia, and Exiliodea. None of them shows an affinity to Pseudolividae.

Introduction

Almost one-fourth of the diversity of marine molluscs is represented by the order Neogastropoda. With more than 12,000 Recent species classified in 40 families, these predatory and scavenging snails are one of the most evolutionary successful taxa of marine molluscs, playing a key role in marine benthic ecosystems at all latitudes and depths. However, although the superfamilies Conoidea [START_REF] Puillandre | Starting to unravel the toxoglossan knot: molecular phylogeny of the "turrids" (Neogastropoda: Conoidea)[END_REF]2011), Buccinoidea [START_REF] Hayashi | The molecular phylogeny of the Buccinidae (Caenogastropoda: Neogastropoda) as inferred from the complete mitochondrial 16S rRNA gene sequences of selected representatives[END_REF][START_REF] Oliverio | Relationships of the haematophagous marine snail Colubraria (Rachiglossa, Colubrariidae), within the neogastropod phylogenetic framework[END_REF], and the families Muricidae [START_REF] Barco | A molecular phylogenetic framework for the Muricidae, a diverse family of carnivorous gastropods[END_REF] and Cancellaridae [START_REF] Modica | Molecular phylogeny of the nutmeg shells (Neogastropoda, Cancellariidae)[END_REF] have been specifically targeted by recent molecular phylogenies, a not inconsiderable fraction of the Neogastropoda -including some ancient and diverse lineages -has remained essentially outside the sphere of molecular systematics. One such untouched group is the so called "miters", a name that refers to members of the two families Mitridae and Costellariidae that together encompass some 800 species (WoRMS, 2015). Miters are widely distributed in tropical and subtropical waters and reach their highest diversity in the Indo-West Pacific in 0-100 meters, where they form a characteristic element of soft bottom benthic communities. Miter shells have long been popular among collectors, and many new species continue to be discovered by amateur taxonomists. Miters usually have high, fusiform shells, with an elongated aperture, strong columellar folds, and an adult size mostly in the 10-50 mm range. Based on this superficial resemblance in shell morphology, a number of costellariid species were originally described under mitrid genera and vice versa. A similar shell is also found in other neogastropod genera, such as Latiromitra (Ptychatractidae) or Microvoluta (Volutomitridae), and the term "mitriform gastropods" [START_REF] Ponder | The morphology of some mitriform gastropods with special reference to their alimentary canal and reproductive systems (Mollusca: Neogastropoda)[END_REF] informally refers to the miters as well as such miterresembling forms.

The state-of-the-art of miters systematics still rests to a large extent on the work carried out by Walter [START_REF] Cernohorsky | A study of mitrid radulae and a tentative generic arrangement of the family Mitridae[END_REF][START_REF] Cernohorsky | Systematics of the families Mitridae and Volutomitridae[END_REF][START_REF] Cernohorsky | The Mitridae of the world. Part 1. The subfamily Mitrinae[END_REF][START_REF] Cernohorsky | The Mitridae of the world. Part 2. The subfamily Mitrinae concluded and subfamilies Imbricariinae and Cylindromitrinae[END_REF]. However, relationships within both these families remain poorly understood, and the monophyly of neither Costellariidae nor Mitridae, and its subfamilies, has ever been tested. Despite Mitridae and Costellariidae have similar shell morphology, their close relationship has been challenged based on radula morphology and anatomy of the digestive tract [START_REF] Iredale | Strange molluscs in Sydney Harbour[END_REF][START_REF] Cernohorsky | A study of mitrid radulae and a tentative generic arrangement of the family Mitridae[END_REF][START_REF] Cernohorsky | Systematics of the families Mitridae and Volutomitridae[END_REF][START_REF] Ponder | The morphology of some mitriform gastropods with special reference to their alimentary canal and reproductive systems (Mollusca: Neogastropoda)[END_REF][START_REF] Fedosov | Evolution of carnivorous gastropods of the family Costellariidae (Neogastropoda) in the framework of molecular phylogeny[END_REF]. What little is available in terms of molecular data likewise suggests that the two families are not close relatives: the single mitrid species sequenced so far clustered with the Muricidae and Olividae, while the single costellariid species showed a closer affinity to the deep water families Ptychatractidae and Volutomitridae [START_REF] Oliverio | Relationships of the haematophagous marine snail Colubraria (Rachiglossa, Colubrariidae), within the neogastropod phylogenetic framework[END_REF]Zou, Lee & Kong. 2011). In fact, the close relationship between Costellariidae and Ptychatractidae was first suggested by Thiele back in 1929. However, a combination of plesiomorphies in morphology of seminal groove) justified the later placement of this group in the family Turbinellidae [START_REF] Bouchet | Revision of the north-East Atlantic bathyal and abyssal Neogastropoda excluding Turridae (Mollusca: Gastropoda)[END_REF][START_REF] Bouchet | The anatomy and systematics of Latiromitra, a genus of tropical deep-water Ptychatractinae (Gastropoda: Turbinellidae)[END_REF]. A recent morphological study, however, revealed a deep water member of the family Costellariidae that showed a remarkable similarity to ptychatractids in foregut anatomy and radula morphology [START_REF] Fedosov | Evolution of carnivorous gastropods of the family Costellariidae (Neogastropoda) in the framework of molecular phylogeny[END_REF]; this discovery supports a close relationship between Costellariidae and Ptychatractidae, and renders morphological differences between the two families quite subtle. With this background of contradictory morphological and molecular data, the relationships of Mitridae, Costellariidae, and other lineages of mitriform gastropods remain quite uncertain and speculative, and require a fresh re-evaluation. The purpose of the present study is precisely to map the phylogeny of mitriform gastropods, with an emphasis on the two families of miters, and to describe their relationships within the Neogastropoda.

Material and Methods

Taxon sampling

The material used in the present study was collected in a series of shore based expeditions and deep water cruises conducted by Museum National d'Histoire Naturelle (MNHN), Institut de recherche pour le Développement (IRD) and Joined Russian Vietnamese Tropical Center in the tropical Indo-Pacific, West Africa and the Mediterranean (Figure 1, Table 1). In the field, molluscs were either anesthetized using magnesium chloride (MgCl2), or in some cases shells were drilled, or, in the most recent expeditions, were processed using a microwave oven [START_REF] Galindo | Using microwaves to prepare gastropods for DNA Barcoding[END_REF]; a tissue clip was then cut and fixed in 95% ethanol. Voucher shells, kept intact for identification, are deposited in MNHN (Table 1). Taxonomy of the family Mitridae follows [START_REF] Cernohorsky | The Mitridae of the world. Part 1. The subfamily Mitrinae[END_REF][START_REF] Cernohorsky | The Mitridae of the world. Part 2. The subfamily Mitrinae concluded and subfamilies Imbricariinae and Cylindromitrinae[END_REF], taxonomy of the families Costellariidae, Ptychatractidae and Volutomitridae is based on several sources as indexed in WoRMS (WoRMS, 2015).

A number of mitriform species in the families Ptychatractidae (genera Exilia, Exilioidea, Ceratoxancus and Latiromitra), Volutomitridae (genera Volutomitra and Microvoluta), Turbinellidae (subfamily Vasinae, genus Vasum; subfamily Columbariinae, genera Coluzea and Fustifusus) were included as putative sister groups of the family Costellariidae. A suite of species from 17 other neogastropod families in the superfamilies Conoidea, Cancellarioidea, Buccinoidea, Muricoidea, Olivoidea and Pseudolivoidea was included in the analysis to ensure adequate representation of major evolutionary lineages of the Neogastropoda and likely inference of mitriform gastropods relationships. Tonna galea (Caenogastropoda, Tonnoidea, Tonnidae) was used as non-neogastropod outgroup. Overall classification follows [START_REF] Bouchet | Classification and nomenclator of gastropod families[END_REF].

PCR amplification and DNA sequencing

Total genomic DNA was extracted from muscle tissue using NucleoSpinR 96 Tissues (Macherey-Nagel) and following the manufacturer's instructions. Fragments of the mitochondrial genes Cytochrome Oxidase I (COI), 16S rRNA and 12S rRNA as well as the nuclear gene H3 were sequenced (Table 2). PCR reactions were performed in 20 µl final volume, containing approximately 3 ng template DNA, 1.5 mM MgCl2, 0.26 mM of each nucleotide, 0.3 µl of each primer, 5% DMSO and 0.75 µl of Taq Polymerase (Qbiogene).

For amplification of each COI, 16S and H3 only one pair of primers has been used (see Table 2). 12S sequences were amplified using two different primer combinations. For most specimens the pair 12SA-12SB was used, producing a fragment of about 370-380 bp. However, due to poor results with these primers in most Mitridae, a primer pair 12SI-12SIII has been used, resulting in a fragment of about 540 bp (Table 2).

The PCR profile for the COI started with 5 min at 95°C followed by 40 cycles with the denaturation at 95°C (35 sec), annealing at 50°C (35 s) and elongation at 72°C (1 min), with final elongation phase at 72°C (10 min). Similar PCR profiles were set for 16S (annealing at 55°C, elongation at 72°C for 50 s), 12S with the primer pair 12SA-12SB (annealing at 57°C, elongation at 72°C for 50 s) and H3 (annealing at 57°C, elongation at 72°C for 45 s). For the primer pair 12SI-12SIII a touch-down PCR protocol with gradual decrease of the annealing temperature from 62 to 56°C has been used. All genes were sequenced for both directions to confirm accuracy of each sequence. The sequencing has been performed by Eurofins.

Chromatograms were edited using CodonCode Aligner version 3.7.1.1.

Sequence alignments

Sequences were aligned for each gene independently using MUSCLE [START_REF] Edgar | MUSCLE: multiple sequence alignment with high accuracy and high throughput[END_REF]. The accuracy of automatic alignments was confirmed by eye using BioEdit version 7.0.9.0 [START_REF] Hall | BioEdit: a user-friendly biological sequence alignment editor and analysis program for Windows 95/98/NT[END_REF]. No indels were detected in protein coding genes COI and H3, the fragments 658 bp and 328 bp in length were sequenced for these two markers respectively. After the alignment of 12S where fragments of different length were amplified, absent positions at 3'-end were treated as missing data.

Datasets

Six datasets were analyzed. The first three datasets correspond to the three mitochondrial genes, COI, 16S and 12S, analyzed separately. The fourth dataset represents concatenated COI, 16S, and 12S sequences (1875 positions) and is referred to as MCPV-3mit (MCPVabbreviated Mitridae-Costellariidae-Ptychatractidae-Volutomitridae). To evaluate the robustness of the mitochondrial phylogeny, a fifth dataset corresponding to the nuclear H3 gene was analyzed.

Finally the concatenated dataset of 2203 positions (referred to as MCPV-4G) was obtained by adding H3 sequences to the MCPV-3mit dataset.

Phylogenetic analyses

Best-fit substitution models were identified for each gene separately, and for each combined dataset using ModelgeneratorV.85 [START_REF] Keane | Assessment of methods for amino acid matrix selection and their use on empirical data shows that ad hoc assumptions for choice of matrix are not justified[END_REF] (Table 2). Best-scoring Maximum Likelihood (ML) trees were estimated using RaxML [START_REF] Stamatakis | RAxML-VI-HPC: maximum likelihood-based phylogenetic analyses with thousands of taxa and mixed models[END_REF] from100 independent searches each starting from distinct random trees. Robustness of the nodes was assessed using the thorough bootstrapping algorithm [START_REF] Felsenstein | Confidence limits on phylogenies: an approach using the bootstrap[END_REF] with 1000 iterations. RaxML was performed on the Cipres Science Gateway (http://www.phylo.org/portal2), using RAxML-HPC2 on XSEDE.

Bayesian Analyses (BAs) were performed running two parallel analyses in MrBayes [START_REF] Huelsenbeck | MrBayes: bayesian inference of phylogeny[END_REF]. For single gene analyses each run consisted of six Markov chains and 5,000,000 generations with default number of swaps chains. For MCPV-3mit and MCPV-4G datasets each analysis consisted of eight Markov chains of 50,000,000 generations with the number of swaps chains set to five. A sampling frequency was one tree each 10,000 generations, and the chain temperature was set at 0.02 in all analyses. Convergence of each analysis was evaluated using Tracer1.4.1 [START_REF] Rambaut | Tracer v1.6[END_REF] to check that all ESS values exceeded 200. Consensus tree were calculated after omitting the first 25% trees as burn-in. The combined MCPV-3mit and MCPV-4G datasets were separated into five and eight unlinked partitions respectively: 16S, 12S, three codon positions of the COI gene (both datasets) plus three codon positions of the H3 gene (MCPV-4G dataset). Analyses were performed on the Cipres Science Gateway (http://www.phylo.org/portal2), using tool MrBayes 3.2.2 on XSEDE.

Radula morphology

Foregut anatomy of sequenced specimens was examined or, in some cases, additional specimens conspecific with sequenced material were dissected. During dissection the buccal mass was isolated and cleaned with diluted bleach (1 part of commercially available bleach to 3-4 parts of water) until tissues are completely dissolved. Cleaned radulae were rinsed in several changes of distilled water and mounted on clear glass cover-slips for SEM investigation.

Results

DNA sequences

Of the 106 species studied, the COI gene was successfully amplified for 99 species, 16S and 12S for 87 species, and H3 for 69 species. All sequences were deposited in GenBank and BOLD (Table 1). For the total count of sequences analyzed and details of the substitution models selected, see Table 2.

Phylogenetic analyses of single gene datasets

The trees obtained after the single gene analyses are characterized by the weak support of most nodes; however, no supported conflicting topologies were found. Because of the weak resolution of the single gene analyses, their results are not discussed here.

Phylogenetic analysis: MCPV-3mit dataset

The topologies of the consensus trees obtained from BA and ML are largely congruent, with the exception of unresolved deepest branches, which show slightly different topologies in trees obtained with BA and ML, though without support in either case. We will mainly discuss the topology of the tree obtained with BA (Fig. 2) and will refer to ML bootstrap support values where applicable.

Within Neogastropoda, Plesiotriton silinoensis Verhecken, 2011 (Cancellariidae) and Melo melo (Lightfoot, 1786) (Volutidae) constitute a well supported clade (PP=1, B=68%) that is sister to all other neogastropods. At the next dichotomy, a rather well supported monophyletic clade corresponding to the superfamily Buccinoidea (PP=0.99, B=69%) splits out from the weakly supported main Neogastropoda grouping (PP=0.95). Six supported major clades can be recognized within the main Neogastropoda grouping, the relationships to each other being unresolved. Three of these major clades correspond to (a) the superfamily Conoidea (monophyletic, PP=1, B=73%), (b) the turbinellid subfamily Vasinae (monophyletic, PP=1, B=100%) and (c) the family Muricidae (monophyletic, PP=0.94). Members of the families Olividae, Olivellidae and Pseudolividae together form a fourth major clade (PP=0.99, B=71%), that can be called Olivoidea. The fifth clade, which is refered to as a "Clade A", comprises species currently assigned to the four neogastropod families Costellariidae, Turbinellidae Within the family Costellariidae, the only species of Thala included in the analysis branches out by itself and forms the first offshoot from the costellariid stem, which includes five well supported clades, the branching order of which is not supported, reflecting the weak resolution of the tree based on the mitochondrial genes. The majority of the species of Vexillum clustered in the well supported grouping Vexillum s.s. (PP=1, B=100%), forming a long branch on the tree. This clade comprises mostly shallow water species and includes in particular V. plicarium (Linnaeus, 1758), the type species of Vexillum, as well as Z. ziervogelii (Gmelin, 1791), the type species of Zierliana. Species of Vexillum s.s. tend to form two separate clades, though none of them is supported. The rather well supported clade Vexillum II (PP=0.98, B=0.5) includes six species conventionally assigned to Vexillum, both from deep water and from subtidal / intertidal depths, in turn forming two separate clades, a well supported one with Vexillum balutense Herrmann, 2009 and V. choslenae Cernohorsky, 1982 (PP=1, B=100%) and a weakly supported one combining the other four species. The three remaining costellariid clades are labeled C-I (PP=1, B=97), C-II (PP=1, B=99) and C-III (PP=1, B=98) on the molecular tree.

These include mostly deep water forms, representing an essentially unrecognized and unnamed diversity of the Costellariidae (of 13 sequenced species, two only can be identified with certainty).

Mitridae

The monophyly of the family Mitridae (PP=1, B=99%) is supported by both BA and ML, as well as its close affinity to the enigmatic deep water family Pyramimitridae (PP=1, B=95%).

The first dichotomy of the Mitridae separates the well supported Charitodoron clade (PP=1, B=100%) from the rest of the Mitridae (PP=1, B=100%). Subsequently, three species, Mitra tuberosa Reeve, 1845, M. bernhardina Röding, 1798 and M.itra peculiaris Reeve, 1845 split out from the general mitrid stem, forming three independent lineages, though the lack of support in the corresponding nodes leaves the possibility of alternative branching. Later on, we will refer to the combined group including Charitodoron species, Mitra tuberosa, M. bernhardina and M. peculiaris as "basal Mitridae". The remaining 37 mitrid species form a rather well supported core clade (PP=0.97, B=63%), which in turn consists of four major groupings (referred to as clades M-I to M-IV), either well supported (M-I, M-II and M-IV), or consisting of a single species (M-III). Clade M-I (PP=1, B=63%) combines two species of Pterygia (monophyletic, PP=1, B=100%), including its type species, P. dactylus (Linnaeus, 1767), and two species currently placed in Mitra, M. glabra Swainson, 1821 andM. incompta (Lightfoot, 1786). Clade M-II (PP=1, B=69%) contains an assortment of Mitra species that form several well supported clades and a set of single-species lineages with unsupported relationships. One of these well supported clades is formed by Mitra mitra (Linnaeus, 1758), the type species of Mitra, and the closely related M. papalis (Linnaeus, 1758), and it will consequently be referred to as Mitra s.s.

Another well supported grouping in the M-II clade corresponds to Nebularia (monophyletic PP=1, B=96%). Three clades within M-II are solely represented by deep water, mostly undescribed, forms (on the tree referred to as Mitridae DW-1 to 3), and we did not find any genus-group name to designate them. Clade M-II also encompasses two lineages which correspond to the genera Domiporta (monophyletic, PP=1, B=100%) and Ziba (only represented by Z. carinata (Swainson, 1824), the type species of the genus). As mentioned before, clade M-III includes a single species, Strigatella paupercula (Linnaeus, 1758), the type species of Strigatella. Clade M-IV (PP=1, B=100%) includes 13 species traditionally classified in the genera Neocancilla, Scabricola, Imbricaria, Cancilla, Ziba, and Subcancilla, which were all allocated to the subfamily Imbricariinae by [START_REF] Cernohorsky | The Mitridae of the world. Part 2. The subfamily Mitrinae concluded and subfamilies Imbricariinae and Cylindromitrinae[END_REF]. Three well supported lineages can be distinguished within that clade, one comprising the monophyletic Neocancilla (PP=1, B=98%), monophyletic Scabricola (represented by two species of the subgenus Swainsonia) and

Phylogenetic analysis: MCPV-4G dataset

The tree obtained after the BA of the MCPV-4G dataset (Fig. 3) is similar to the mitochondrial genes based tree discussed above and largely congruent with it, but the branching order differs in some clades. In general the four genes tree has better resolution, and many of the crucial nodes have higher support values. The composition of major neogastropod groupings remains unchanged, while the relationships among them are rather weakly supported. Among the noteworthy changes are increased supports of clade A (PP=1, B=60%) and of the Volutomitridae+Exilioidea grouping (PP=0.94, B=68%).

While the topology of the Mitridae segment of the MCPV-4G tree is nearly identical to the MCPV-3mit tree, the arrangement of Costellariidae clades differs. In the four genes tree, the most derived position is occupied by Vexillum s.s. (PP=1, B=100%), which in species composition corresponds to the Vexillum s.s. clade of the MCPV-3-mit tree and only slightly differs in internal branching. Conversely, the former clade Vexillum II is now split into several separate lineages, which cluster with the Vexillum s.s. clade. Vexillum patriarchalis (Gmelin, 1791), V. rubrum (Broderip, 1836) and V. nodospiculum (Cernohorsky, 1870) Given the increased resolution of the MCPV-4G tree compared to the mitochondrial genes tree, our results will be discussed in the context of the phylogenetic scheme inferred from the four genes dataset. Of the three nominal genera of Costellariidae studied, Thala was represented by a single species, so its monophyly was not tested; Zierliana comes out monophyletic, but its inclusion into the Vexillum s.s. clade implies a revision of its rank; Vexillum is undoubtedly polyphyletic, and the extent of its polyphyly depends on how broad its boundaries are defined (see Discussion).

Among mitrid genera, monophyly is supported for Charitodoron, Pterygia, Domiporta, Neocancilla, Cancilla and Scabricola and for the subgenus Mitra (Nebularia). Monophyly is not rejected for Subcancilla, of which a single species has been studied, and for Strigatella. The genera Imbricaria and Ziba are definitely polyphyletic. It is noteworthy that Z. carinata, the type species of Ziba, ended up within the clade M-II, separately from three other species traditionally placed in Ziba, Z. fulgetrum, Z. flammigera and Z. insculpta, which cluster in clade M-IV.

Finally the genus Mitra appears highly polyphyletic: species conventionally assigned to Mitra are found in all four clades of the core Mitridae and also among the "basal Mitridae".

Radula morphology

All species in the Vexillum s.s. clade are similar in radula morphology: they have triserial radulae with a multicuspidate rachidian and simple, unicuspid laterals (Figs. 4,5). The shape of rachidian ranges from robust with relatively short cusps, in Zierliana ziervogeli and Vexillum semifasciatum (Lamarck, 1811) (Fig. 5), to more elaborate, bow-shaped with long pointed cusps in Vexillum exasperatum (Gmelin, 1791) or V. gloriae Poppe, Tagaro & Salisbury, 2009 (not shown). The number of cusps varies from seven (Vexillum cancellarioides, Fig. 5) to more than 20 (V. exasperatum). A similar radula is found in the two species of Vexillum s.l., Vexillum rubrum and Vexillum nodulospiculum.

The other costellariid species (clades C-I -C-IV, Protoelongata and Thala) have monocuspid laterals similar to those found in Vexillum s.s., but differ in structure of the rachidian, which bears only three cusps, although it varies in shape, robustness, base width, orientation and length of the cusps (Fig. 4,5). "Vexillum" balutense has a rachidian with two minor intermediate cusps, positioned on both sides of the central cusp (Fig. 5). Lateral teeth vary from slender, sickle-shaped in Costellariidae gen. sp. (IM-2013-40629) to robust, almost triangular, in "Vexillum" isaoi (Kuroda & Sakurai, 1959).

The same general radula morphology characterizes the ptychatractid genera Ceratoxancus, Latiromitra and Exilia and, also, the columbariine Coluzea cf. liriope Harasewych, 1986, but Exilioidea is remarkably different (Figs 4,5). In Ceratoxancus cf. melichrous [START_REF] Kantor | The anatomy and systematics of Ceratoxancus, a genus of deepwater Ptychatractinae (Gastropoda: Turbinellidae) with labral spine[END_REF] and two species of Latiromitra, L. crosnieri Bouchet &[START_REF] Bouchet | The anatomy and systematics of Latiromitra, a genus of tropical deep-water Ptychatractinae (Gastropoda: Turbinellidae)[END_REF]L. barthelowi (Bartsch, 1942), there is a robust rachidian bearing three short and blunt cusps on a moderately wide base, and rather slender laterals; in Exilia krigei (Kilburn, 1971), the rachidian has a proportionally wider base and closely set, long and pointed cusps; in Coluzea cf. liriope, the only distinguishing feature is the very narrow base of the rachidian. The rachidian of Exilioidea is characterized by the massive base and three cusps, situated on the tip of long blade-like projection. This projection of the rachidian apical segment is directed along the longitudinal axis of the radula and forms a distinct longitudinal furrow, so that the apical part of a tooth interlocks in the furrow of the next one.

Mitridae show considerable variation in shell and radular morphology (Figs 6,7). A triserial radula with a rather small rachidian and broad, multicuspidate laterals characterizes members of clade M-II as well as Strigatella paupercula of the clade M-III, and Mitra peculiaris and Charitodoron in the "basal Mitridae". Typically, the lateral teeth are nearly rectangular, bear 14 to more than 20 cusps that are stronger medially and gradually reduce in size towards the margins. The rachidian is about three times narrower than the laterals and bears 5-7 subequal, rather short and stout cusps. However, in one unidentified species (IM-2013-40651) of clade M-II, the rachidian and laterals are similar, each tooth has a slightly convex margin that bears 12-13 equal cusps.

The three species in clade M-IV also have triserial radulae, but their morphology differs notably from that seen in clade M-II, and also from each other. The number of cusps on the laterals is reduced to six (Ziba flammigera), five (Scabricola fusca (Swainson, 1824)) or even one (Imbricaria olivaeformis), and one cusp is always much longer and stronger than the others, giving the laterals the appearance of a can opener (Figs 6,7). Remarkably, the position of the enlarged cusp differs between species: in Ziba flammigera the second proximal cusp is the largest, while in Scabricola fusca it is the most distal one. The morphology of the rachidian also differs between species; Scabricola fusca possesses a rachidian resembling a hair comb with long cusps of equal length, but Imbricaria olivaeformis and Ziba flammigera have rachidians with two central cusps greatly enlarged in comparison to those positioned laterally.

Finally, three species, Pterygia dactylus (clade M-I), "Mitra" bernhardina and "M". tuberosa ("basal Mitridae") have monoserial radulae, lacking lateral teeth and retaining rachidians only (Figs 6, 7); these rachidians vary in shape from species to species, and are all greatly reduced in size, not exceeding 20 µm in width.

Discussion

Radular morphology

Our results on radula morphology essentially fall in line with the published data on Costellariidae [START_REF] Cernohorsky | A study of mitrid radulae and a tentative generic arrangement of the family Mitridae[END_REF][START_REF] Cernohorsky | Systematics of the families Mitridae and Volutomitridae[END_REF][START_REF] Bandel | The radulae of Carribbean and other Mesogastropoda and Neogastropoda[END_REF][START_REF] Fedosov | Evolution of carnivorous gastropods of the family Costellariidae (Neogastropoda) in the framework of molecular phylogeny[END_REF], Ptychatractidae [START_REF] Bouchet | Transfer of Exilioidea Grant & Gale, 1931 to Turbinellidae, with descriptions of three new species (Neogastropoda)[END_REF][START_REF] Kantor | The anatomy and systematics of Ceratoxancus, a genus of deepwater Ptychatractinae (Gastropoda: Turbinellidae) with labral spine[END_REF][START_REF] Bouchet | The anatomy and systematics of Latiromitra, a genus of tropical deep-water Ptychatractinae (Gastropoda: Turbinellidae)[END_REF][START_REF] Kantor | A revision of the Recent species of Exilia, formerly Benthovoluta (Gastropoda: Turbinellidae)[END_REF], Mitridae [START_REF] Cernohorsky | A study of mitrid radulae and a tentative generic arrangement of the family Mitridae[END_REF][START_REF] Cernohorsky | Systematics of the families Mitridae and Volutomitridae[END_REF][START_REF] Ponder | The morphology of some mitriform gastropods with special reference to their alimentary canal and reproductive systems (Mollusca: Neogastropoda)[END_REF], Volutomitridae [START_REF] Bouchet | New Caledonia: the major center of biodiversity for volutomitrid molluscs (Mollusca: Neogastropoda: Volutomitridae)[END_REF]) and Columbariinae [START_REF] Harasewych | New Columbariinae (Gastropoda: Turbinellidae) from the Indian Ocean[END_REF]. However, some of our results contradict those published earlier, or deserve special attention as novel and important for future discussion.

The radula of Exilioidea agrees with the description and illustrations of [START_REF] Bouchet | Transfer of Exilioidea Grant & Gale, 1931 to Turbinellidae, with descriptions of three new species (Neogastropoda)[END_REF]. Based on the tricuspidate rachidian and triangular unicuspid laterals, Bouchet & Warén suggested the placement of Exilioidea in the family Turbinellidae [which, at the time [START_REF] Bouchet | Revision of the north-East Atlantic bathyal and abyssal Neogastropoda excluding Turridae (Mollusca: Gastropoda)[END_REF], included Turbinellinae, Ptychatractinae, Columbariinae and Vasinae]. However, the presence of the strong central projection with its margins half-folded to form a kind of trough recalls the radula of Volutomitridae. The radula of Exilioidea, which combines rather plesiomorphic characters of ptychatractid radulae and derived ones of Volutomitridae, supports the relationships of these two groups as suggested by the molecular phylogeny.

All studied species in the Vexillum s.l. clade have radulae with multicuspidate rachidian, as those studied by [START_REF] Fedosov | Evolution of carnivorous gastropods of the family Costellariidae (Neogastropoda) in the framework of molecular phylogeny[END_REF]. [START_REF] Cernohorsky | Systematics of the families Mitridae and Volutomitridae[END_REF] illustrated the radula of Vexillum patriarchalis with a tricuspidate rachidian, matching the radula found by [START_REF] Azuma | On the radulae of the family Vexillidae[END_REF] in other Vexillum species, sometimes classified in the subgenus Pusia, such as V. (Pusia) hizenense Pilsbry, 1921 [=Vexillum inerme (Reeve, 1845)], and V. (Pusia) australe (Swainson, 1820) [START_REF] Ponder | Families Mitridae and Costellariidae[END_REF][START_REF] Robin | Mitridae Costellariidae. Xenophora and Conchbooks[END_REF]. Corresponding to our results, Vexillum rubrum and V. cancellarioides (Anton, 1838), which are referable to Pusia based on shell morphology, have a multicuspidate rachidian. Furthermore, in our results Pusia is not consistent with a single monophyletic grouping, as V. cancellarioides is included in the Vexillum s.s. clade. Further studies are needed to clarify the position of V. patriarchalis in Costellariidae and its relationships to Vexillum (Pusia) microzonias, the type of Vexillum (Pusia).

The radula with morphologically identical rachidian and laterals, found in specimen IM-2013-40651, is remarkably close to the one described in Pleioptygma helenae (Radwin & Bibbey, 1972) the only Recent species of the family Pleioptygmatidae [START_REF] Quinn | Pleioptygmatidae, a new family of mitriform gastropods (Prosobranchia: Neogastropoda)[END_REF]. This family was erected largely based on the peculiar foregut anatomy and radular morphology of Pleioptygma helenae., and a critical reassessment of the status of Pleioptygmatidae is required.

While morphological data can give some hints on its possible relationships, molecular data would be critical. However, it is already clear that a radula with three morphologically identical teeth in a transversal row cannot be regarded as something outstanding in Neogastropoda; a radula of the same morphology is present also in Colubraria (Colubrariidae: Buccinoidea) [START_REF] Oliverio | Relationships of the haematophagous marine snail Colubraria (Rachiglossa, Colubrariidae), within the neogastropod phylogenetic framework[END_REF].

One of the most interesting results is the finding that several independent mitrid lineages have developed uniserial radulae. To date uniserial radulae have been reported only in Pterygia [START_REF] Ponder | Families Mitridae and Costellariidae[END_REF], but they have most likely been overlooked in other mitrids because of their minute size (7-15 µm broad), which complicates preparation.

Relationships among major groups of mitriform gastropods

All our phylogenetic analyses support the monophyly of the families Mitridae, Volutomitridae and Costellariidae, although the boundaries of latter are disputable (see below). In the analyses of both 4G and 3-mit datasets, the four genera of Ptychatractidae do not form a monophyletic grouping, but cluster into three unrelated lineages:

(a) The Ceratoxancus-Latiromitra clade shows a close affinity to Costellariidae, a relationship which is highly supported in all analyses (including the analyses of single gene datasets), and a logical conclusion is to expand the boundaries of the family Costellariidae to include these two genera as basal offshoots. The possible distant relationship betweeen Latiromitra-Ceratoxancus and other ptychatractids was suggested by [START_REF] Harasewych | A revision of the genus Benthovoluta with notes on the evolution of the subfamily Ptychatractinae (Prosobranchia: Turbinellidae)[END_REF] based on the cladistic analysis of a morphological dataset. The supposed relationships of Ceratoxancus have long remained controversial; [START_REF] Sakurai | On a new species of the Xancidae, Ceratoxancus elongatus (Gastropoda)[END_REF] suggested an affinity to the Mitridae, and [START_REF] Cernohorsky | The taxonomy of Benthovoluta hilgendorfi (von Martens) and allied turbinellid genera (Mollusca: Volutacea)[END_REF] to the Volutomitridae. A relationship of Latiromitra to Vexillum was envisioned by [START_REF] Wenz | Gastropoda. Teil 1, Allgemeiner Teil und Prosobranchia[END_REF], who treated Latiromitra as a section of Vexillum.

(b) The genus Exilia is more distantly related to this newly defined costellariid-Ceratoxancus-Latiromitra clade.

(c) The close relationship of Exilioidea and Volutomitridae is weakly supported by molecular data, but is also suggested by radula morphology.

In conclusion, although the family Ptychatractidae obviously requires revision, it is at present hampered by the lack of material of crucial genera, in particular Ptychatractus.

The family Volutomitridae is found to be only distantly related to the Costellariidae, with both Volutomitridae and Costellariidae turning out to be more closely related to genera formerly classified as ptychatractids. In our analyses, the branching within Clade A thus contradicts the phylogenetic scheme of [START_REF] Oliverio | Relationships of the haematophagous marine snail Colubraria (Rachiglossa, Colubrariidae), within the neogastropod phylogenetic framework[END_REF], who found the volutomitrid genus Microvoluta to be most closely related to Vexillum; the same scheme was reproduced later by [START_REF] Zou | Additional gene data and increased sampling give new insights into the phylogenetic relationships of Neogastropoda, within the caenogastropod phylogenetic framework[END_REF]. In fact, a close relationship between Costellariidae and Volutomitridae is also contradicted by the morphology of the radula and digestive system [START_REF] Ponder | The morphology of some mitriform gastropods with special reference to their alimentary canal and reproductive systems (Mollusca: Neogastropoda)[END_REF][START_REF] Fedosov | Evolution of carnivorous gastropods of the family Costellariidae (Neogastropoda) in the framework of molecular phylogeny[END_REF]. We have therefore examined the voucher specimen (MNHN IM-2009-4609) of [START_REF] Oliverio | Relationships of the haematophagous marine snail Colubraria (Rachiglossa, Colubrariidae), within the neogastropod phylogenetic framework[END_REF] Microvoluta sp. It is morphologically close to specimens MNHN IM-2013-40628 and MNHN IM-2013-40627 of our deep water Costellariidae lineage C-II, and its COI sequence even suggests it is conspecific with the former (pairwise distance 0.019). Thus we assign the specimen, studied by [START_REF] Oliverio | Relationships of the haematophagous marine snail Colubraria (Rachiglossa, Colubrariidae), within the neogastropod phylogenetic framework[END_REF] to Costellariidae, suggesting an initial misidentification that has resulted in a distorted branching in the Ptychatractidae-Volutomitridae-Costellariidae segment of their tree. Admittedly, shell differences between Costellariidae and Volutomitridae are rather subtle, and in day-to-day practice specimens with a bulbous paucispiral protoconch are commonly referred to Microvoluta, while those with a multispiral protoconch are referred to Vexillum.

One of the crucial hypotheses to be confirmed or rejected is whether the families Costellariidae and Mitridae are closely related. Our results unequivocally demonstrate that these two families are unrelated, as they cluster in two different well supported major groupings of the Neogastropoda. The revealed close affinity between Mitridae and the enigmatic family Pyramimitridae is one of the most unexpected results of our analysis. The family Pyramimitridae was considered extinct until living members of several undoubtedly pyramimitrid genera were discovered in the deep water fauna of the Indo-Pacific [START_REF] Kantor | Lost and found: The Eocene family Pyramimitridae (Neogastropoda) discovered in the Recent fauna of the Indo-Pacific[END_REF]. The initial molecular phylogenetic analysis failed to attribute Pyramimitridae to any known neogastropod lineage. Despite Mitridae and Pyramimitridae end up closely related in the present molecular phylogeny, they differ overly in radula morphology, with wide and flattened multicuspidate laterals and milticuspidate rachidian in Mitridae, vs triangular laterals and pointed unicuspid rachidian in Pyramimitridae. Although limited anatomical data are available at the moment for Pyramimitridae, we can already point out significant differences between the two families. Thus, the buccal mass occupies a basal position in pyramimitrids, while it is apical in mitrids. Members of the family Pyramimitridae have no epiproboscis (see below), but possess a relatively well developed gland of Leiblein; the latter is lacking in Mitridae. No synapomorphies of the Mitridae-Pyramimitridae clade are known at present.

Published data on the morphology of the monotypic (in the Recent fauna) family

Pleioptygmatidae suggest a close relationship to the Mitridae. The anterior alimentary canal of the Mitridae is characterized by the presence of a specific organ -the epiproboscis -, which is not found in any other family of Neogastropoda, and is often considered an autapomorphy for the family [START_REF] West | Functional morphology of the proboscis of Mitra catalinae Dall, 1920 (Mollusca: Gastropoda: Mitridae) and the evolution of the mitrid proboscis[END_REF][START_REF] Ponder | Families Mitridae and Costellariidae[END_REF]. We suspect that the "proboscis introvert" described by [START_REF] Quinn | Pleioptygmatidae, a new family of mitriform gastropods (Prosobranchia: Neogastropoda)[END_REF] for Pleioptygma helenae is, in fact, an epiproboscis, as it does not differ in morphology and topology from the mitrid epiproboscis [START_REF] Ponder | The morphology of some mitriform gastropods with special reference to their alimentary canal and reproductive systems (Mollusca: Neogastropoda)[END_REF]. Unfortunately, the narrow geographic range and rarity of Pleioptygma makes it hard to target for molecular studies, which would be essential to clarify unequivocally its position.

Deep relationships within the Neogastropoda

The current empirical classification of the Neogastropoda [START_REF] Bouchet | Classification and nomenclator of gastropod families[END_REF] places the family Ptychatractidae in the superfamily Pseudolivoidea, and [START_REF] Oliverio | Relationships of the haematophagous marine snail Colubraria (Rachiglossa, Colubrariidae), within the neogastropod phylogenetic framework[END_REF] phylogenetic analysis also suggested an affinity of the Mitridae to Olivoidea and Pseudolividae.

However, none of these assignments is supported here, as none of the three evolutionary lineages referable to the Ptychatractidae shows a relationship to the two pseudolivids -Fulmentum sepimentum (Rang, 1832) and Benthobia sp. -included in the present analysis. The latter two taxa fall into a well supported clade with Olivoidea, separated from Clade A, suggesting only a distant relationship between ptychatractids and Pseudolividae. [START_REF] Ponder | Classification of the Caenogastropoda and Heterostropha -A list of the family-group names and higher taxa[END_REF] treated Ptychatractinae as a subfamily of Turbinellidae, together with Columbariinae, Vasinae, Turbinellinae and Tudiculinae. Members of the different turbinellid subfamilies were found to share several anatomical features, e.g. an open seminal groove and a radula with tricuspidate rachidian and simple, unicuspid laterals. These anatomical features were regarded as ancestral for the Neogastropoda, and Turbinellidae sensu [START_REF] Ponder | Classification of the Caenogastropoda and Heterostropha -A list of the family-group names and higher taxa[END_REF] was often regarded as one of most ancient groups of the Neogastropoda [START_REF] Ponder | Families Mitridae and Costellariidae[END_REF]. Our phylogenetic analysis places Columbariinae and various ptychatractids in a well supported clade A, with Vasinae as a sister group (though with no significant support). However, ptychatractids, vasines and columbariines do not form a monophyletic group; instead ptychatractids show closer affinities to Costellariidae and Volutomitridae with their derived anatomy. Therefore, the family Turbinellidae sensu [START_REF] Ponder | Classification of the Caenogastropoda and Heterostropha -A list of the family-group names and higher taxa[END_REF] and [START_REF] Bouchet | Classification and nomenclator of gastropod families[END_REF] is definitely a non-monophyletic group based essentially on shared plesiomorphies.

With the most basal relationships among Neogastropoda still unresolved, we refrain from a critical revision of the classification at the level of superfamilies. However, some incongruences between the currently accepted systematic arrangement and the present phylogenetic reconstructions (Fig. 8) deserve special mention. Our results confirm the monophyly of the neogastropod superfamilies Buccinoidea and Conoidea, and the monophyly of the Olivoidea and Cancellarioidea is also not rejected. Pseudolivoidea are recovered polyphyletic (see above). The vast majority of the neogastropod evolutionary lineages, including those specifically targeted in the present study, are currently classified in the superfamily Muricoidea [START_REF] Bouchet | Classification and nomenclator of gastropod families[END_REF]. The families currently classified in Muricoidea (WoRMS, 2015)

Relationships within the Costellariidae: Vexillum versus "basal" lineages

The family Costellariidae is commonly perceived as consisting of the large and extremely diverse genus Vexillum and a few, sometimes bizarre, small genera like Zierliana or Visaya. Our analysis evidences a series of previously unrecognized costellariid lineages, essentially consisting of still unnamed taxa. The four costellariid lineages C-I -C-IV (Fig. 3) correspond to four to-be-established genera with numerous undescribed new species, which will be named elsewhere.

While Vexillum species with multicuspidate rachidians occupy the most derived position in our phylogenetic trees, costellariids other than Vexillum, which are characterized by a tricuspidate rachidians, form deep lineages. This radula morphology, which can be regarded as plesiomorphic, is characteristic also for Ceratoxancus, Latiromitra and Exilia, as well for some other lineages of the superfamily Muricoidea [START_REF] Fedosov | Evolution of carnivorous gastropods of the family Costellariidae (Neogastropoda) in the framework of molecular phylogeny[END_REF]. The difference in radula morphology between Vexillum and the "basal Costellariidae" parallels differences in the structure of the foregut glands. Earlier studies on the anatomy of the digestive system of costellariids revealed a large, bulky gland of Leiblein in the only studied species referable to "basal Costellaridae" [START_REF] Fedosov | Evolution of carnivorous gastropods of the family Costellariidae (Neogastropoda) in the framework of molecular phylogeny[END_REF], and a similar gland of Leiblein is present in Latiromitra [START_REF] Bouchet | The anatomy and systematics of Latiromitra, a genus of tropical deep-water Ptychatractinae (Gastropoda: Turbinellidae)[END_REF], Ceratoxancus [START_REF] Kantor | The anatomy and systematics of Ceratoxancus, a genus of deepwater Ptychatractinae (Gastropoda: Turbinellidae) with labral spine[END_REF] and Exilia [START_REF] Harasewych | A revision of the genus Benthovoluta with notes on the evolution of the subfamily Ptychatractinae (Prosobranchia: Turbinellidae)[END_REF][START_REF] Kantor | A revision of the Recent species of Exilia, formerly Benthovoluta (Gastropoda: Turbinellidae)[END_REF]. By contrast, many species of Vexillum are characterized by the reduction of the gland of Leiblein and the presence of a long, highly convoluted, glandular tube, originating from the stripped off folds of the mid-oesophagus, and resembling the venom gland of the Conoidea. An intermediate morphology, with a still noticeable gland of Leiblein and already a rather short tubular duct, was found in Vexillum cf.

salisburyi [START_REF] Cernohorsky | The Mitridae of the world. Part 1. The subfamily Mitrinae[END_REF]V. rubrum (Fedosov &[START_REF] Fedosov | Evolution of carnivorous gastropods of the family Costellariidae (Neogastropoda) in the framework of molecular phylogeny[END_REF], the latter species falling into the Vexillum s.l. group. The origin and evolution of the genus Vexillum thus appears to have been linked to the appearance of a multicuspidate rachidian and a rearrangement of the foregut that possibly allowed these snails to develop a new feeding strategy(ies), permitting their explosive radiation. It is however at present unclear whether the multicuspidate rachidian appeared only once in the evolutionary history of the Costellariidae. It could be a synapomorphy of the Vexillum s.l. clade (as supported by our 4G dataset), or it could have evolved independently in different Costellariidae lineages. The presence of tricuspidate rachidians in some species of Vexillum (Pusia) complicates the picture, and the affinities of these species need to be further examined. Moreover the radula of "Vexillum" balutense of the "basal" clade C-IV, with its rachidian bearing two rudimentary cusps flanking the central cusp, may be considered intermediate between the simple tricuspidate and true multicuspidate.

The discovery of multiple costellariid taxa with tricuspidate rachidians and a well developed, non-tubular gland of Leiblein renders the morphological difference between the Costellariidae and traditional Ptychatractidae quite subtle. In fact, the foregut anatomy of "basal Costellariidae" is much closer to the one found in Ptychatractidae than it is to the one found in Vexillum. Although all costellariids as currently construed lack an operculum, and an operculum is still present in Ceratoxancus and Latiromitra, we nevertheless suggest the transfer of Ceratoxancus and Latiromitra from the Ptychatractidae to the Costellariidae. Although this rearrangement extends the boundaries of the Costellariidae, it remains a monophyletic group.

Altogether, the transfer of Ceratoxancus and Latiromitra to Costellariidae, the revised status of Zierliana and Protoelongata, and the future erection of new genera for newly identified deep water lineages will significantly impact the generic composition of the family. [START_REF] Cernohorsky | A study of mitrid radulae and a tentative generic arrangement of the family Mitridae[END_REF][START_REF] Cernohorsky | Systematics of the families Mitridae and Volutomitridae[END_REF] added the subfamily Imbricariinae.

Relationships within the Mitridae: Systematic challenges and morphological diversity

Based on a comprehensive analysis of the anatomy of several species of mitriform gastropods, [START_REF] Ponder | The morphology of some mitriform gastropods with special reference to their alimentary canal and reproductive systems (Mollusca: Neogastropoda)[END_REF] pulled Vexillinae outside Mitridae and synonymized Imbricariinae with Mitrinae.

However, the validity of Imbricariinae was restored by [START_REF] Ponder | Classification of the Caenogastropoda and Heterostropha -A list of the family-group names and higher taxa[END_REF], and the same three mitrid subfamilies were recognized in [START_REF] Bouchet | Classification and nomenclator of gastropod families[END_REF].

Our phylogenetic analysis supports the monophyly of the family Mitridae and recognizes a "core Mitridae" group, which is well supported and encompasses almost 90% of the species studied. Clade M-I includes the monophyletic Pterygia, the only genus classified in the subfamily Cylindromitrinae, and therefore the monophyly of Pterygia implies the monophyly of Cylindromitrinae. With some reservations we equate clade M-I to a subfamily Cylindromitrinae, however the clade M-I definitely encloses Cylindromitrinae. The well supported clade M-II includes a diversity of mitrids among which Mitra s.s. represented in our dataset by Mitra mitra, the type species of the genus, and M. papalis; the name Mitrinae is thus applicable to clade M-II.

Clade M-III is represented by the single species Strigatella paupercula, the type species of Strigatella that was treated as a separate genus by [START_REF] Cernohorsky | The Mitridae of the world. Part 1. The subfamily Mitrinae[END_REF], and subsequently was placed in Mitra as a subgenus [START_REF] Robin | Mitridae Costellariidae. Xenophora and Conchbooks[END_REF]WoRMS, 2015). As it is found not immediately related to Mitra s.s, and, furthermore, falls outside the Mitrinae clade, the status of Mitra (Strigatella) has to be revised and Strigatella ranked as a full genus, if not placed in its own subfamily. Finally the well supported clade M-IV includes the genera Imbricaria, Neocancilla, Subcancilla and Scabricola and the name Imbricariinae is available for it. However, two genera that are traditionally classified as imbricariine, Domiporta and Ziba, turn out to be closer to Mitra s.s. than to other imbricariines, and their classification must be revised.

Despite the three mitrid subfamilies (with the newly suggested circumscriptions) are supported, there emerge two problems of congruence between the phylogeny of the Mitridae revealed by our analysis and the current classification of the family: 1) the genus Mitra turns out to be polyphyletic, comprising multiple unrelated lineages that are spread throughout the mitrid tree, and it requires a thorough revision; and 2) some mitrid lineages ("basal Mitridae" and Strigatella paupercula of the M-III clade) are not included in any of the three subfamilies. A separate subfamily for each clade of the "basal Mitridae", as well as for Strigatella paupercula of the "core Mitridae", would need to be established. Moreover, the assignment of the two mitrid species which cluster with Pterygia on our molecular tree, but differ in shell morphology, also remains unclear.

The typical mitrid radula with wide multicuspidate laterals characterizes most members of clade M-II (subfamily Mitrinae), but is also found in two "basal Mitridae", Charitodoron sp. and Mitra peculiaris. For this reason, we consider this radula morphology ancestral for the family Mitridae. Whereas this morphology seems to have been conserved in most members of the subfamily Mitrinae, in other mitrid clades the radula has undergone transformations and three different trends can be distinguished:

(i) an increase in the number of cusps of the central tooth, resulting in rachidian and laterals with similar morphology (mitrine species IM-2013-40651 of clade DW2);

(ii) a reduction in the number of cusps of the laterals, with the notable enlargement of one cusp (species of Imbricariinae);

(iii) a complete loss of the laterals, concommitant with a considerable size reduction of the radula; a uniserial radula is found in Mitra tuberosa, M. bernhardina and Pterygia spp., where they are likely to be the result of parallel evolution.

The diversity of radula morphology in the family Mitridae by far exceeds that of Costellariidae, as well as that of many other neogastropod families. Although this might suggest a variety of feeding strategies, the diet of over 30 Indo-Pacific species of Mitra, Imbricaria, Nebularia, and Strigatella is known to consist exclusively of sipunculans [START_REF] Taylor | Habitats and diet of predatory gastropods at Addu Atoll, Maldives[END_REF]1984;[START_REF] Taylor | Diets of sand-living predatory gastropods at Piti Bay, Guam[END_REF][START_REF] Taylor | Dietary and anatomical specialization of mitrid gastropods (Mitridae) at Rottnest Island, Western Australia. In: The Marine flora and fauna of Rottnest Island[END_REF][START_REF] Ponder | Families Mitridae and Costellariidae[END_REF][START_REF] Harasewych | Anatomy and biology of Mitra cornea Lamarck 1811 (Mollusca, Caenogastropoda, Mitridae) from the Azores[END_REF], and Mitridae have been regarded as having the most specialized diet among Neogastropoda [START_REF] Taylor | The diet of coral-reef Mitridae (Gastropoda) from Guam; with a review of other species of the family[END_REF][START_REF] Harasewych | Anatomy and biology of Mitra cornea Lamarck 1811 (Mollusca, Caenogastropoda, Mitridae) from the Azores[END_REF]. An epiproboscis, which was considered an adaptation for feeding on the soft-bodied sipunculans [START_REF] West | Functional morphology of the proboscis of Mitra catalinae Dall, 1920 (Mollusca: Gastropoda: Mitridae) and the evolution of the mitrid proboscis[END_REF], is present in all mitrids studied anatomically [START_REF] Risbec | Contribution a l'etude anatomique de quelques especes de mitres de la Presqu'ile de Noumea[END_REF][START_REF] Ponder | The morphology of some mitriform gastropods with special reference to their alimentary canal and reproductive systems (Mollusca: Neogastropoda)[END_REF][START_REF] West | Functional morphology of the proboscis of Mitra catalinae Dall, 1920 (Mollusca: Gastropoda: Mitridae) and the evolution of the mitrid proboscis[END_REF][START_REF] Ponder | Families Mitridae and Costellariidae[END_REF][START_REF] Harasewych | Anatomy and biology of Mitra cornea Lamarck 1811 (Mollusca, Caenogastropoda, Mitridae) from the Azores[END_REF][START_REF] Simone | Anatomical description of Ziba carinata from Ghana (Caenogastropoda, Mitridae)[END_REF]. Local sipunculan guilds rarely comprise more than 10 species, i.e. their diversity is notably lower than that of Mitridae, such that an overlap in prey species among syntopic mitrid species is inevitable. A series of studies carried out by [START_REF] Taylor | Habitats and diet of predatory gastropods at Addu Atoll, Maldives[END_REF]1984;[START_REF] Taylor | Diets of sand-living predatory gastropods at Piti Bay, Guam[END_REF], 1989) on Indo-Pacific mitrids showed that most are not species specific predators, and the same prey species may be consumed by taxonomically closely or distantly related species of snails. For example, the sipunculan Aspidosiphon tenuis Sluiter, 1886, was shown to contribute significantly to the diet of at least 6 mitrids [Nebularia fraga (Quoy & Gaimard, 1833), N. chryzalis (Reeve, 1844), N. cucumerina (Lamarck, 1811), Mitra acuminata Swainson, 1824, Strigatella litterata (Lamarck, 1811), and Imbricaria conovula (Quoy & Gaimard, 1833)]. In addition, any one species of miter may consume 3-4 different species of sipunculans at any one locality. The broad range of radula types in mitrids, with their feeding specialization on similar prey items, is thus unexpected. It is noteworthy, however, that all the species for which morphological data are available are referable to our "core Mitridae", while none of the "basal Mitridae" lineages has been studied to date.

Conclusion

This study revealed a major incongruence between the currently accepted classification of the Mitridae, Costellariidae and Ptychatractidae and the relationships evidenced by molecular phylogenetic trees. Mitriform gastropods do not form a monophyletic group, with Mitridae standing apart from the rest. The families Pleioptygmatidae and Pyramimitridae are most closely related to the Mitridae, the former based on published data on radula and shell morphology, the latter based on the present phylogenetic analysis. Costellariidae display a close relationship to the ptychatractid genera Ceratoxancus and Latiromitra, and a more distant affinity to Exilia, the family Volutomitridae and the "turbinellid" subfamilies Columbariinae and possibly Vasinae.

Our results also reject an affinity of Ptychatractidae and Pseudolividae, and the superfamily status of Pseudolivoidea is questioned. Finally, our results also show the need for a revised circumscription of the families Ptychatractidae and Turbinellidae, as both are found paraphyletic.

The existing taxonomic framework cannot accommodate the revealed diversity of Costellariidae and Mitridae phylogenetic lineages. A revision of both Costellariidae and Mitridae, with the establishment of multiple new genera for inferred phylogenetic lineages, is needed. In particular the polyphyly of Mitra suggests that a number of species currently assigned to Mitra should be reassigned elsewhere, in genera still to be established. ;21. "Mitra" tuberosa;22. "Mitra" bernhardina;23. "Mitra" peculiaris;24. Pterygia dactylus;25. Strigatella paupercula;26. Mitra mitra;27. Mitridae Gen. sp.;28. Scabricola fusca;29. "Imbricaria" olivaeformis;30. "Ziba" fulgetrum.

Captions

(

  Columbariinae), Volutomitridae and Ptychatractidae. Finally the sixth major clade (PP=1, B=95%) combines the families Mitridae (PP=1, B=95%) and Pyramimitridae (PP=1, B=100%), both monophyletic. Clade A Within clade A, the species currently assigned to the neogastropod families Costellariidae and Volutomitridae together with the turbinellid subfamily Columbariinae form three well supported clades (PP=1, B=100%), consistent with their accepted taxonomic status. Conversely, the species of Ptychatractidae do not form a single grouping and three distinct clades can be recognized corresponding to (a) the genus Exilia, (b) the genus Exilioidea and (c) the genera Ceratoxancus and Latiromitra. Analysis of the three genes dataset recognizes Exilioidea as a sister group to the family Volutomitridae, though with no support, while the Ceratoxancus-Latiromitra clade clusters with Costellariidae (PP=1, B=100%). The affinities of Exilia within clade A remain uncertain.

  Imbricaria olivaeformis (Swainson, 1821). The second lineage combines two closely related species of the genus Cancilla (Cancilla fibula Poppe, Tagaro & Salisbury, 2009, and C. cf. fibula) and Mitra schepmani Salisbury & Guillot de Suduiraut, 2003. Finally the third lineage of clade M-IV combines species traditionally assigned to Ziba (Z. flammigera (Reeve, 1844), Z. fulgetrum (Reeve, 1844) and Z. insculpta (A. Adams, 1851)), Subcancilla (S. pugnaxa Poppe, Tagaro & Salisbury, 2009) and Imbricaria (represented by I. conularis (Lamarck, 1811), the type species of the genus).

  are closest to Vexillum s.s., and the highly supported clade formed by Vexillum s.s. and these three species (PP=1, B=85) will thus be referred to as Vexillum s.l. The single species lineage of Vexillum dekkersi forms a sister group to Vexillum s.l.; V. dekkersi Herrmann, Stossier & Salisbury, 2014 and a set of similar species were recently placed in a separate subgenus Protoelongata Herrmann, Stossier & Salisbury, 2014, and this name can be used for that clade. Finally the well supported clade (refered to as C-IV) of two deep water species, V. balutense and V. cf. choslenae, form a sister group to the Vexillum s.l.-Protoelongata clade with high support of the resulting grouping (PP=1, B=83%).

  fall in five inferred major clades: (1) a Muricidae clade, (2) a Vasinae clade, (3) a Mitridae-Pyramimitridae clade, (4) a clade ("clade A") consisting of the families, Costellariidae, Turbinellidae (Columbariinae), Volutomitridae and Ptychatractidae, and (5) a Cancellariidae + Volutidae clade (See Fig. 8). Despite the lack of resolution of deep nodes in our trees, at least two points contradict the currently accepted circumscription of the Muricoidea: (i) the inclusion of the ptychatractids into the otherwise muricoid clade A; and (ii) the supported grouping of the volute Melo melo with the cancellariid Plesiotriton silinoensis. Nevertheless, even the revised position of the Ptychatractidae and the exclusion of Volutidae from Muricoidea would not ensure the monophyly of resulting Muricoidea.

  [START_REF] Thiele | Handbuch der systematischen Weichtierkunde[END_REF] recognized three subfamilies in the family Mitridae: Mitrinae, Cylindrinae and Vexillinae [= Costellariinae].

Figure 1 .

 1 Figure 1. Map of sampled localities. Black circles mark deep water cruises, grey circles shallow water shore-based expeditions. Diameters of circles proportional to the number of samples used in the present study (see legend in the top left corner).

Figure 2

 2 Figure 2 Phylogenetic tree of mitriform gastropods and outgroup neogastropod taxa obtained after analysis of the MCPV-3mit dataset. The topology corresponds to the tree obtained with BA, support values are indicated for each node as BA PP values (when ≥0.8) / ML bootstrap values (when ≥50).

Figure 3 .

 3 Figure 3. Phylogenetic tree of mitriform gastropods and outgroup neogastropod taxa obtained after the analysis of the MCPV-4G dataset. The topology corresponds to the tree obtained with BA, support values are indicated for each node as BA PP values (when ≥0.8) / ML bootstrap values (when ≥50).

Figure 4 .

 4 Figure 4. Clade A subtree of the Bayesian tree obtained after analysis of the 4G dataset. Support values are indicated for each node as BA PP values (when ≥0.8) / ML bootstrap values (when ≥50). Voucher shells for those species studied morphologically are illustrated, numbers in bold correspond to SEM photos of their radulae [shown at the bottom for Volutomitridae (Microvoluta joloensis -1), Exilioidea sp. (2) and Columbariinae (Coluzea cf. liriope -3) and on figure 5 for Exilia, Ceratoxancus, Latiromitra and Costellariidae].

Figure 5 .

 5 Figure 5. Radular morphology of Costellariidae. Numbers correspond to the vouchers shown on figure 4: 4. Exilia krigei; 5. Ceratoxancus cf melichrous; 6. Latiromitra barthelowi; 7.

Figure 6 .

 6 Figure 6. Mitridae subtree of the Bayesian tree obtained after analysis of the 4G dataset. Support values are indicated for each node as BA PP values (when ≥0.8) / ML bootstrap values (when ≥50). Voucher shells for those species studied morphologically are illustrated, numbers in bold correspond to SEM photos of their radulae (shown on figure 7).

Figure 7 .

 7 Figure 7. Radular morphology of Mitridae. Numbers correspond to the vouchers shown on figure 6. 20. Charitodoron sp.; 21. "Mitra" tuberosa; 22. "Mitra" bernhardina; 23. "Mitra"

Figure 8 .

 8 Figure 8. BA tree of the MCPV-4G dataset with the current superfamily assignment showed in colour.

  Vexillum cancellarioides; 8. Vexillum semifasciatum; 9. Zierliana ziervogeli; 10. Vexillum plicarium; 11. Vexillum exasperatum; 12. Vexillum nodospiculum; 13. Vexillum rubrum; 14. Vexillum (Protoelongata) dekkersi; 15. "Vexillum" balutense; 16. Thala sp.; 17. Costellariidae Gen. sp.; 18. Costellariidae Gen. sp.; 19. "Vexillum" isaoi.

Table . 1

 . . List of specimens analyzed. Type species of genera shown in bold.

	COSTELLARIIDAE MITRIDAE BORSONIIDAE	Gen. Ziba Bathytoma	sp. cf. abyssicola neocaledonica	IM-2013-4814 IM-2013-40654 IM-2007-17857	PAPUA NIUGINI EXBODI	CP3949 CP3829	05°12'S 145°51'E, 380-407 m 22°02'S 167°05'E, 350-360 m	EU015653	HQ401661	HQ401591	EU015761
	Family MITRIDAE MITRIDAE BUCCINIDAE COSTELLARIIDAE COSTELLARIIDAE COSTELLARIIDAE MITRIDAE BUCCINIDAE MITRIDAE MITRIDAE BUCCINIDAE MITRIDAE MITRIDAE BUCCINIDAE CANCELLARIIDAE	Genus Cancilla Ziba Neptunea Thala Vexillum Vexillum Cancilla Neptunea Charitodoron Ziba Volutharpa Charitodoron Ziba Phos Plesiotriton	species fibula fulgetrum cumingi sp. plicarium costatum cf. fibula amianta sp. flammigera perryi sp. insculpta senticosus silinoensis	MNHN IM-2007-38689 IM-2013-18112 NSMK_MS_000480 IM-2013-3389 IM-2013-13646 IM-2009-11058 IM-2013-40646 T777 IM-2007-38306 IM-2013-40656 LSGB232042 IM-2013-40658 IM-2013-40657 LSGB232091 IM-2007-32123	Expedition TARASOC PAPUA NIUGINI PAPUA NIUGINI PAPUA NIUGINI SANTO 2006 EXBODI MAINBAZA NT2011 MAINBAZA NT2011	Station DW3441 PR240 PM25 PM27 DR64 CP3822 CC3157 ND7 CC3171 ND7	collection data 16°43'S 151°26'W, 350-360 m 05°08.2'S 145°48.7'E, 3-20 m 05°01.1'S 145°47.9'E, intertidal 04°59.3'S 145°47.6'E, intertidal 15°27.6'S 167°14.3'E, 6-35 m 12º10.443'N 109º16.298'E, 15-21°52'S 166°51'E, 341-506 m 18 m 21°46'S 36°25'E, 1410-1416 m 25°59'S 34°42'E, 771-776 m 12º10.443'N 109º16.298'E, 15-18 m	COI HM180715.1 JN052941.1 16S HQ401586.1 HQ401718.1 HQ401655.1 12S HQ833870.1 HQ834142.1 H3 GQ290613.1 GQ290613.1 GQ290613.1 GQ290634.1 JN053003.1 HQ833930.1 HQ833869.1 HQ834141.1 JN053008.1 JN052944.1 HQ833885.1 HQ834156.1 FM999158.1 FM999106.1 FM999075.1
	COSTELLARIIDAE COSTELLARIIDAE COSTELLARIIDAE COSTELLARIIDAE COSTELLARIIDAE COSTELLARIIDAE COSTELLARIIDAE COSTELLARIIDAE COSTELLARIIDAE COSTELLARIIDAE COSTELLARIIDAE COSTELLARIIDAE COSTELLARIIDAE COSTELLARIIDAE COSTELLARIIDAE COSTELLARIIDAE COSTELLARIIDAE COSTELLARIIDAE COSTELLARIIDAE COSTELLARIIDAE MITRIDAE MITRIDAE MITRIDAE CONIDAE MITRIDAE CONIDAE MITRIDAE MITRIDAE FASCIOLARIIDAE MITRIDAE PTYCHATRACTIDAE Ceratoxancus Vexillum Vexillum Vexillum Vexillum Vexillum Vexillum Vexillum Vexillum Vexillum Vexillum Vexillum Vexillum Vexillum Vexillum Vexillum Vexillum "Vexillum" "Vexillum" "Vexillum" "Vexillum" Domiporta Domiporta Gen. Conus Gen. Conus Domiporta Gen. Turrilatirus Imbricaria MELONGENIDAE Hemifusus MITRIDAE Imbricaria PTYCHATRACTIDAE Ceratoxancus MURICIDAE Purpura MITRIDAE Mitra PTYCHATRACTIDAE Ceratoxancus MURICIDAE Nucella MITRIDAE Mitra MITRIDAE Mitra MITRIDAE Mitra MITRIDAE Mitra PTYCHATRACTIDAE Ceratoxancus MURICIDAE Thais PTYCHATRACTIDAE Ceratoxancus NASSARIIDAE Nassarius PTYCHATRACTIDAE Exilia OLIVELLIDAE Olivella OLIVIDAE Oliva MITRIDAE Mitra PTYCHATRACTIDAE Exilia MITRIDAE Mitra PTYCHATRACTIDAE Exilia OLIVIDAE Ancillina MITRIDAE Mitra PTYCHATRACTIDAE Exilia OLIVIDAE Amalda MITRIDAE Mitra PTYCHATRACTIDAE Exilia PSEUDOLIVIDAE Benthobia MITRIDAE Mitra PTYCHATRACTIDAE Exilioidea PSEUDOLIVIDAE Fulmentum MITRIDAE Mitra MITRIDAE Mitra PTYCHATRACTIDAE Exilioidea PTYCHATRACTIDAE Latiromitra PYRAMIMITRIDAE Teremitra MITRIDAE Mitra PTYCHATRACTIDAE Latiromitra PYRAMIMITRIDAE Teremitra MITRIDAE Nebularia TURBINELLIDAE PYRAMIMITRIDAE Vaughanites (COLUMBARIINAE) Fustifusus TURBINELLIDAE RAPHITOMIDAE Taranis	pagodula deshayesi micra semifasciatum sanguisuga virgo exasperatum gloriae scitulum dekkersi herosae cancellarioides rubrum patriarchalis acupictum nodospiculum balutense cf. choslenae isaoi cf. isaoi granatina praestantissima sp. consors sp. pagodus filiaris sp. turritus conularis sp. ternatanus olivaeformis teramachii rudolphi bernhardina leios lapillus incompta tuberosa papalis sophia sp. haemastoma cf. melichrous succinctus vagrans sp. amethystina cf. rosacea hilgendorfi s.l. christinae hilgendorfi s.l. cf. sumatrana mitra hilgendorfi s.l. optima glabra krigei sp. shepmani sp. sepimentum peculiaris sp. sp. barthelowi efatensis cornicula crosnieri efatensis maesta superstes pinicola sp.	IM-2007-30310 IM-2007-30259 IM-2013-4734 IM-2013-11594 IM-2013-14245 IM-2013-13079 IM-2013-11680 IM-2013-40634 IM-2013-40633 IM-2007-30242 IM-2013-40630 IM-2013-40631 IM-2013-1747 IM-2013-10241 IM-2013-40635 IM-2013-40632 IM-2013-40637 IM-2007-38378 IM-2013-40636 IM-2007-34557 IM-2013-40641 IM-2013-40642 IM-2013-40651 IM-2007-17939 IM-2013-40655 IM-2007-17914 IM-2013-12956 IM-2013-40133 IM-2009-11059 IM-2013-18043 IM-2007-39277 LSGB233031 IM-2013-18062 IM-2007-36797 LSGB23014 IM-2013-13618 IM-2007-35024 MZUR_BAU00187 IM-2007-30175 IM-2007-30311 IM-2007-30174 IM-2007-30056 IM-2007-38552 MZUR_BAU00696 IM-2013-40623 LSGB2340502 IM-2007-34067 IM-2009-24367 IM-2007-31988 IM-2007-30309 IM-2007-34612 IM-2007-32131 IM-2007-38603 IM-2007-31956 IM-2013-40639 IM-2007-36877 IM-2009-22263 IM-2013-40640 IM-2007-38331 IM-2009-31002 IM-2013-40645 IM-2007-34633 IM-2013-52003 IM-2013-6168 IM-2013-40650 IM-2013-40625 IM-2007-35820 IM-2013-52073 IM-2013-40661 IM-2007-38178 IM-2013-52074 IM-2013-40648 IM-2007-35222 IM-2007-43438 IM-2013-52046	SANTO 2006 SANTO 2006 PAPUA NIUGINI PAPUA NIUGINI PAPUA NIUGINI PAPUA NIUGINI PAPUA NIUGINI NT2011 EXBODI PANGLAO 2004 MIRIKY TUHAA PAE 2013 PAPUA NIUGINI PAPUA NIUGINI NT2011 AURORA 2007 BIOPAPUA EXBODI BIOPAPUA AURORA 2007 INHACA 2011 NT2010 BIOPAPUA EXBODI PAPUA NIUGINI PAPUA NIUGINI PAPUA NIUGINI TARASOC PAPUA NIUGINI TERRASSES PAPUA NIUGINI NORFOLK 2 SANTO 2006 PANGLAO 2004 SANTO 2006 SANTO 2006 TARASOC EXBODI SALOMON 2 KARUBENTHOS 2012 SANTO 2006 SANTO 2006 AURORA 2007 PANGLAO 2005 TARASOC PANGLAO 2005 INHACA 2011 MIRIKY INHACA 2011 Western Australia WE01 DB12 DS31 PB28 PM12 PR68 PD24 PR14 ND3 CP3824 B7 CP3204 AT04 PB10 PS04 ND3 CP2734 CP3747 CP3826 CP3748 CP2709 MR15 D3 CP3671 CP3821 PD23 CP4035 PR203 DW3394 PR214 DW3077 PB19 DW2060 DR78 R75 DR87 DR09 DW3401 DW3914 CP2251 GD41 DR09 AT44 CP2751 CP2383 DW3493 CP2350 MR15 CP3187 MR4 MAINBAZA CC3171 AURORA 2007 CP2685 EXBODI DW3926 AURORA 2007 CP2690 ZANAGA D502 PAPUA NIUGINI PR218 BIOPAPUA CP3728 PAPUA NIUGINI CP3963 SALOMONBOA 3 CP2800 PAPUA NIUGINI CP4058 Sicily, Cyracuse MIRIKY PAPUA NIUGINI CP4058 no data MIRIKY CP3288 TERRASSES DW3120 PAPUA NIUGINI CP4049	15°36.6'S 167°10.1'E, 10-18 m 15°31.4'S 167°09.7'E, 5 m 05°11.9'S 145°49.6'E, 10 m 05°00.2'S 145°47.6'E, 0-1 m 05°01.6'S 145°48.1'E, 5 m 05°05.3'S 145°48.6'E, 3-6 m 05°12'S 145°48.1'E, 2-3 m 12°10.084'N 109°17.771'E, 6-18 m 21°57'S 166°58'E, 280-296 m 09°35.9'N 123°51.8'E, 4-30 m 12°37.03'S 48° 30.3' E, 59-60 m 23°25.13'S 149°27.0'W, 12 m 05°17.9'S 145°46.7'E, 10 m 05°10.0'S 145°50.1'E, 12 m 12°10.084'N 109°17.771'E, 6-18 m 15°57'N 121°49'E, 453-460 m 05°33'S 153°59'E, 458 m 21°52'S 166°51'E, 354-509 m 05°37'S 154°01'E, 398-399 m 15°12'N 121°34'E, 244-296 m 26°00.0'S 32°54.4'E, 4 m 04°04'S 151°56'E, 585-601 m 12°10.084'N 109°17.771'E, 6-18 21°53'S 166°50'E, 211-440 m m 04°31'S 145°31'E, 380-382 m 05°06'S 145°49.2'E, 3-7 m 15°49'S 148°17'W, 500-510 m 05°10.3'S 145°48.5'E, 1-19 m 23°15'S 168°14'E, 420-540 m 05°10.2'S 145°50.4'E, 1-8 m 24°40'S 168°39'E, 582-600 m 05°05.1'S 145°48.6'E, 10 m 15°28.4'S 167°15.2'E, 25 m 09°32.8'N 123°42.1'E, 3-35 m 15°38.5'S 167°15.1'E, 13 m 15°51'S 148°18'W, 789-831 m 19°45'S 165°45'E, 620-725 m 07°28' S 156°14' E, 1000-1050 16°20.900'S 61°32.217'W, 2 m m 15°34.600'S 167°13.800'E,12 m 15°34.6'S 167°13.8'E, 12 m 15°36'N 121°56'E, 1456-1471 m 9°31.400'N 124°00.600'E, 602-15°36'S 167°03'E, 86-118 m 738 m 17°28'S 149°27'W, 556-565 m 08°45'N 123°18'E, 338-351 m 26°6.300'S 32°58.00'E, 17-19 m 12°30'S 48°08'E, 691-695 m 14°59.617'N 123°5.900'E, 1155-26°00.0'S 32°54.4'E, 4 m 25°59'S 34°42'E, 771-776 m 1302 m 15°16.94'S 124°06.3'E, 11 m 14°58'N 123°03'E, 1071-1147 m 4°42.25'S E 11°47.0'E, 20 m 18°35'S 164°20'E, 364-473 m 05°07.3'S 145°49.4'E 2°54.669'S 142°10.772'E, 535-05°06'S 145°53'E, 960-980 m 540 m 08°41'S 161°04'E, 556-864 m 2°54.669'S 142°10.772'E, 535-07°52'S 148°01'E, 498-501m 540 m 37°0.460'N 15°18.62'E, 6-12 m 14° 31.9' S 47° 26.54' E, 46-54 22°44'S 167°15'E, 320-360 m 3°19.413'S 143°27.239'E, 422-m 425 m	EU015751 EU015729 HQ401585.1 HQ401714.1 HQ401651.1 HQ401672 HQ401605 FJ868151 FJ868136 JN053014.1 JN052950.1 HQ833889.1 HQ834160.1 EU015858 EU015836 HQ834096 HQ833968 HQ833919 HQ834189 FM999169.1 FM999119.1 FM999088.1 FM999171.1 FM999121.1 FM999090.1 HQ834079.1 HQ833949.1 HQ833901.1 HQ834172.1 KF840066 KF840067
	COSTELLARIIDAE COSTELLARIIDAE COSTELLARIIDAE MITRIDAE MITRIDAE MITRIDAE (COLUMBARIINAE) TEREBRIDAE TURBINELLIDAE (COLUMBARIINAE) TONNIDAE TURBINELLIDAE TURRIDAE	"Vexillum" Zierliana Zierliana Nebularia Nebularia Neocancilla Coluzea Terebra Coluzea Tonna Turris	pratasense ziervogelii woldemari connectens pediculus papilio cf. liriope cingulifera groschi galea babylonia	IM-2007-35967 IM-2013-15865 IM-2013-12694 IM-2013-2342 IM-2013-12705 IM-2013-12560 IM-2007-38972 IM-2007-16735 IM-2007-38280 LSGB22802 IM-2007-17754	BIOPAPUA PAPUA NIUGINI PAPUA NIUGINI PAPUA NIUGINI PAPUA NIUGINI PAPUA NIUGINI MAINBAZA MAINBAZA	CP3741 PM41 PM8 PB16 PB15 PR24 CP3139 CP3143	09°14'S 152°18'E, 694-766 m 05°08.1'S 145°49.3'E, 0-1 m 05°15.3'S 145°46.6'E, 0-1 m 05°10.7'S 145°47.7'E, intertidal 05°04.7'S 145°48.9'E, 5 m 05°12.3'S 145°48.8'E 23°35'S 36°06'E, 1092-1195 m 23°32'S 35°46'E, 264-277 m	EU015735 HQ834116 EU015677	EU685670 HQ833984 HQ401715	EU685379 HQ833862 HQ401652	EU015842.1 HQ834135 EU015786
	COSTELLARIIDAE MITRIDAE (VASINAE) VOLUTIDAE	Gen. Neocancilla Vasum Melo	sp. clathra sp. melo	IM-2007-30347 IM-2007-30178 IM-2009-14647 LSGB2400102	SALOMON 2 SANTO 2006 ATIMO VATAE	CP2189 DR73 TA24	08°20' S 160°02' E, 660-854 m 15°22.5'S 167°11.4'E, 10-25 m 25°23.4'S 44°14.0'E, 15-17 m	HQ834086	HQ833959	HQ833911	HQ834182
	COSTELLARIIDAE COSTELLARIIDAE MITRIDAE TURBINELLIDAE (VASINAE) COSTELLARIIDAE MITRIDAE VOLUTOMITRIDAE COSTELLARIIDAE MITRIDAE VOLUTOMITRIDAE COSTELLARIIDAE MITRIDAE VOLUTOMITRIDAE COSTELLARIIDAE MITRIDAE VOLUTOMITRIDAE COSTELLARIIDAE MITRIDAE OUTGROUPS COSTELLARIIDAE MITRIDAE MITRIDAE BELOMITRIDAE	Gen. Gen. Neocancilla Vasum Gen. Pterygia Microvoluta Gen. Pterygia Volutomitra Gen. Strigatella Volutomitra Gen. Subcancilla Volutomitra Gen. Scabricola Gen. Ziba Scabricola Belomitra	sp. sp. rufescens turbinellus sp. dactylus joloensis sp. sinensis glabella sp. paupercula zigzag sp. pugnaxa sp. sp. fusca sp. carinata casta bouteti	IM-2007-38256 IM-2007-39400 IM-2013-40644 LSGB23801 IM-2013-40624 IM-2013-14989 IM-2013-40620 IM-2013-40132 IM-2009-15439 IM-2007-35070 IM-2013-40627 IM-2013-15188 IM-2007-35073 IM-2013-40628 IM-2007-34547 IM-2007-38357 IM-2013-40629 IM-2013-40643 IM-2013-40638 IM-2013-40647 IM-2007-31989 IM-2007-38678	EBISCO TARASOC INHACA 2011 BIOPAPUA PAPUA NIUGINI BIOPAPUA PAPUA NIUGINI ATIMO VATAE CONCALIS PANGLAO 2005 PAPUA NIUGINI CONCALIS BIOPAPUA AURORA 2007 TERRASSES BIOPAPUA INHACA 2011 PAPUA NIUGINI ZANAGA PANGLAO 2004	DW2606 DW3452 MD22 CP3719 PM39 DW3720 CP4055 CP3568 DW3003 CP2381 PM39 DW2944 DW3777 CP2716 DW3123 CP3632 MS8 CP4079 531DW R38	19°37'S 158°42'E, 442-443 m 25°59.7'S 32°46.8'E, 22 m 16°51'S 151°19'W, 600-705 m 05°12.1'S 145°48.4'E, intertidal 06°03'S 147°35'E, 520-523 m 06°03'S 147°36'E, 410 m 25°04.7'S 47°03.4'E, 64-65 m 18°34'S 163°08'E, 450-454 m 03°03'S 142°18'E, 370-374 m 05°12.1'S 145°48.4'E, intertidal 18°59'S 163°24'E, 320-335 m 08°43'N 123°19'E, 259-280 m 14°30'N 121°41'E, 335-356 m 22°53'S 167°13'E, 420-450 m 05°01'S 152°00'E, 40-619 m 25°59.5'S 32°52.9'E, 9-17 m 06°56'S 147°08'E, 700-740 m 04°43.0'S 11°47.0'E, 17 m 04°34'S 145°52'E, 960 m 09°29.4'N 123°56.0'E, 6-37 m	HQ834084 JQ950224.1	HQ833957 EU870550.1	HQ833909 EU870525.1	HQ834180

Table 2 .

 2 Primers used for amplification and sequences data

			annealing
			temperature	amplification	alignment	Number of	substitution
	Gene	Primers	Cº	length bp	length bp	sequences	model (hLRTs)	I	gamma
	COI	HCOI -LCOI	48-50	658	658	120	GTR+I+G	0,44	0,35
	16S	16SA -16SB	55	~550	597	108	TVM+I+G	0,41	0,51
	12S 12S	12SA -12SB 12SI -12SIII	57 57*	~380 ~540	620 620	107	GTR+I+G	0,27	0,62
	H3	H3A -H3B	55	328	328	84	TrN+I+G	0,59	0,64

Acknowledgements

The molecular material in this paper originates from numerous shore-based expeditions and deep sea cruises, conducted respectively by MNHN and Pro-Natura International (PNI) as part of the Our Planet Reviewed programme, and by MNHN and Institut de Recherche pour le Développement (IRD) as part of the Tropical Deep-Sea Benthos programme. Funders and sponsors include the French Ministry of Foreign Affairs, the Philippines Bureau of Fisheries and Aquatic Research (BFAR), the Total Foundation, Prince Albert II of Monaco Foundation, Stavros Niarchos Foundation, and Richard Lounsbery Foundation, We thank, among others, Virginie Héros, Philippe Maestrati, Pierre Lozouet, Barbara Buge, Ellen Strong and Laurent Charles for their role in specimens processing during the expeditions and curation. We thank Catherine Rausch (MNHN) and Nadezda Surovenkova (IPEE) for SEM facilities. The present study was largely accomplished during a visiting curatorship of the first author to MNHN in 2013 and 2014, supported also by a Metchnikov postdoctoral fellowship granted by the French Embassy in Russia. The molecular phylogenetic studies were supported by the "Service de Systématique Moléculaire" (UMS 2700 CNRS-MNHN), the ATM Barcode (PIs:

Sarah Samadi and Jean-Noël Labat / MNHN) and by grants from the Russian foundation of basic researches RFBR-14-04-31048-mol-а and RFBR-14-04-00481-a.