Diversity and systematics of Haminoeidae gastropods (Heterobranchia: Cephalaspidea) in the tropical West Pacific Ocean: new data on the genera Aliculastrum, Atys , Diniatys and Liloa

Four genera of Haminoeidae gastropods inhabiting the tropical West Pacific ( Aliculastrum , Atys , Diniatys , and Liloa ) were studied based on the combined analyses of live animals, external morphology, anatomy and shells aided by scanning electron microscopy and molecular sequencing. Eleven species are described including two new to Science, namely Atys pittmani sp. nov. and Atys ukulele sp. nov. . The putative synapomorphies of the genera Aliculastrum , Diniatys , and Liloa are discussed. High levels of morpho-anatomical variability were found among representatives of the genus Atys , which hampered the recognition of synapomorphies. (H 6.4 mm). Formed by three parts: prostate, seminal duct and penial region; prostate elongated-ovoid, bilobed, proximal lobe larger and opaque-yellowish, striations on proximal lobe sometimes present, distal lobe semi-translucent, creamy-white; prostate inserts laterally at the beginning of posterior part of seminal duct, seminal duct broad, anterior part semi-translucent, posterior part opaque-yellowish; penial region elongated, translucent, about same length as seminal duct, slightly narrower than seminal duct.


Introduction
Haminoeidae is the most genera-rich family of Cephalaspidea gastropods (Burn & Thompson 1998). It was first proposed by Pilsbry (1895) with the name Hamineinae as a subfamily of Akeridae with the single genus Haminea (=Haminoea). Species in this family are found worldwide in both tropical and temperate waters. Their shells show great variability ranging from typical bulloid to cylindrical-elongate. Spiral grooves can be present either at the ends or covering the entire shell. Shells are usually thin, translucent, and fragile but some species in the genera Atys and Aliculastrum possess solid thick shells. The mantle and other body parts are usually dull and cryptically coloured, although some species can be colourful and be even capable of changing colour to suit the environment (Edlinger 1982;Gosliner et al. 2008). They have a muscular buccal bulb containing chitinous jaws and a radula formed by a central tooth that varies in shape between genera plus hook-shaped lateral teeth in variable numbers. A gizzard is present with three plates containing pointed rods for shredding algal tissue and diatoms, the main diet of haminoeids (Gosliner 1991;Mikkelsen 1996;Malaquias et al. 2009a;Malaquias 2010).
Several studies have been conducted in the West Pacific since the 19 th century and major expeditions yielded significant contributions to the knowledge of cephalaspids in the region. The Astrolabe Expedition produced some of the first insights into the diversity of cephalaspids from the Australasian region (Quoy & Gaimard 1833). The Challenger Expedition led to a detailed catalogue of cephalaspidean species (Watson 1886). Bergh (1901) produced a major contribution to the knowledge of West Pacific cephalaspids with focus on the Philippines. Schepman (1913) published an extensive account on the molluscs, including the cephalaspids collected during the Dutch Siboga Expedition. Major monographs with a global focus such as Adams (1850), Sowerby (1868;1870;1873), and Pilsbry (1895;1896), also included significant accounts of cephalaspids from the Indo-West Pacific. In addition, the works of Pease (1860), Pilsbry (1917Pilsbry ( , 1921, and Kay (1979) described a high number of species from the Hawaiian archipelago. A common point shared by all these publications is that the taxonomic work is mostly based upon the shells alone and very limited anatomical data was included.
Numerous regional checklists, short anatomical accounts and books with chapters devoted to the Haminoeidae have been published. Examples are Pease (1860), Pilsbry (1917Pilsbry ( , 1921, Kay (1979) and Malaquias (2011) (for the Hawaiian islands), Habe (1952Habe ( , 1970 (Japan and western Pacific in general), Lin (1990Lin ( , 1997 Preece (1995) (Pitcairn Islands), Carlson & Hoff (2000, 2003 (Mariana Islands), Qi (2004) (China), Burn (2006)  As with other cephalaspidean gastropods, haminoeids have experienced extensive taxonomic confusion due to intraspecific variation and interspecific similarity of shells, until now the chief character used for species description and diagnoses. In the present account the diversity of four genera of Haminoeidae (Aliculastrum, Atys, Diniatys, and Liloa) inhabiting shallow waters of the tropical West Pacific Ocean is studied. New morphoanatomical and shell characters are given to understand the extent of intraspecific variability and help in species delimitation.

Materials and methods
Taxa sampling. Specimens were obtained from museum collections (University Museum of Bergen [ZMBN], Museum national d'Histoire Naturelle, Paris [MNHN], Museum für Naturkunde, Berlin (ZMB) and Florida Museum of Natural History [UF]) and fieldwork carried out in Guam, Hawaii and the Philippines. Collection of specimens was conducted on the intertidal and subtidal down to 30 m deep. Sand, seagrass and algae substrates were examined. Whenever possible live animals were photographed, relaxed, and preserved in 10% formalin and absolute ethanol (> 96%).
Species-level taxonomy. Original descriptions were used as the primary reference for the identification of species. The features examined were shell shape and sculpture, digestive system (radulae, gizzard plates and jaws) and male reproductive system. Specimens were dissected and hard structures (shells, jaws, radulae and gizzard plates) were examined by scanning electron microscopy (SEM). The buccal mass, gizzard and male reproductive system were extracted from the dissected organisms. Radulae were soaked in sodium hypochlorite solution (household bleach) diluted to obtain a concentration of approximately 20% for about 20-40 minutes at room temperature, rinsed in distilled water and flattened with a glass cover-slip. Radulae were mounted for SEM and left to dry overnight. Photographs were taken in several orientations in order to obtain best coverage of the entire structure. Jaws were isolated, cleaned in bleach for about 5-10 mins, followed by cleaning with distilled water. They were then mounted and observed by SEM. The gizzards were opened dorsally and the gizzard plates were extracted and soaked in bleach for 5-10 mins, followed by cleaning with a paintbrush and distilled water, then mounted for SEM. Shells were mounted on SEM stubs to study their microsculpture. All the material prepared for SEM was coated with gold-palladium. An auto-montage imaging system was used to take photographs of the shells before dissection and of gizzard plates after dissection. The male reproductive system was separated from the body, studied and drawn under a dissection microscope with camera lucida.
Preliminary molecular phylogenetic analyses including various representatives of Haminoeidae were performed in parallel to this morphological study. The results of these analyses are part of a master thesis (Too 2011), have been recently presented at an international meeting (Malaquias et al. 2013), and will be published elsewhere. These phylogenetic results were used in part to aid on the generic assignment of the species studied here. The molecular and phylogenetic work followed the methods and protocols described by Malaquias et al. (2009).     broader than outer lateral teeth, triangular base with slight semi-circular projection outwardly, groove often presents along outer margin; outer lateral teeth hook-shaped, slender, broad base, with broad semi-circular projection outwardly, grooves along both outer and inner margins, size increases outwardly but outermost tooth smallest.
Gizzard plates (Figs 4G, H): Three gizzard plates; broader at anterior part, narrower posteriorly; 10 transverse ridges with crescent shape on each side of pseudo-rachis; ridges covered by tiny rods with pointed tips, gaps between ridges smooth, high density of rods on ridges throughout plates.
Remarks. After attempts to locate Helbling's type material we concluded that his collection seems to have been lost or is at least presently untraceable. Aliculastrum cylindricum shows variation in shell morphology; it is usually subcylindrical, and more or less convex (Pilsbry 1895, pl. 33, figs 60, 61;present study, Fig. 2A). There are specimens with more cylindrical and elongated shells and this latter form has been named Atys elongata (Pilsbry 1895, pl. 33, fig.62). Shells that are angular above the mid-part have been named Atys solida (Pilsbry 1895, pl. 33, figs 63, 64;present study, Fig. 2B). Martens & Langkavel (1871) stated that Atys alicula might be a synonym but Pilsbry (1895) rejected this view after examining the type specimen. Atys alicula was described as a thin and hyaline shell (Adams 1850) and does not resemble Aliculastrum cylindricum. Pilsbry (1895) mentioned that Atys succisa could be a juvenile of Aliculastrum cylindricum but this was rejected by Martens (1880) without giving sound arguments. Atys succisa was described as a thin shell with very fine spiral grooves at both ends (Adams 1850;Sowerby 1870). In addition, Pilsbry (1895) also placed Atys angustata described by Smith (1872) as a synonym of Aliculastrum cylindricum. However, Smith (1872)'s description as "very narrow species, thinner at both ends, strongly sinuated posteriorly" sounded more similar to Aliculastrum debilis.
The shell variability of this species led to taxonomic confusion with several synonyms available but also its generic placement has been contentious. Pilsbry (1896) introduced the name Aliculastrum, because of the robust cylindrical shell and thick columella that is neither truncated nor folded; this classification has since being followed by several authors (e.g. Habe 1952;Lin 1997;Qi 2004;Willan & Tagaro 2010) but others include the species in the genus Atys (e.g. Gosliner et al. 2008). Compared to the type species of Atys -Atys naucum -which has an ovoid inflated shell and gizzard plates with very fine ridges that are occupied by tiny rods (Carlson & Hoff 1999), Aliculastrum cylindricum shows different characters: cylindrical shell and gizzard plates with large crescentshaped ridges. Moreover, preliminary molecular data (Too 2011) supports the validity and inclusion of this species in the genus Aliculastrum.
Several authors referred to this species as umbilicated (e.g. Helbling 1779; Adams 1850; Sowerby 1870), but Chemnitz (1780) showed this to be simply a depression of the posterior part of the shell, which is corroborated by our findings. Descriptions of the radula can vary significantly and this more than reflecting intraspecific variability likely results from authors dealing with more than one species. For example, Vayssière (1906) studied specimens from Borneo and the Philippines and recorded a radula with a formula of 9.1.9, whereas Bergh (1901) founded in specimens from the Red Sea a radular formula of 35-45 x 12.1.12 with denticulated inner lateral teeth. Macnae (1962) reported a formula of 11.1.11 for specimens from South Africa with teeth depicting a fine denticulation along the inner margin.
Gizzard plates (Figs 5G, H, 6A, B): Three gizzard plates; broader at anterior part, narrower posteriorly; 8-11 ridges, pseudo-rachis present; For specimens from Tahiti (Fig. 6A), 8 ridges, rachis absent or faint; ridges covered by rods with pointed tips along top edge, smaller rods with pointed tips densely at both anterior and posterior sides of ridges, gaps between ridges smooth, high density of rods on ridges throughout plates.
Male reproductive system ( Fig. 5I): Total length 3.2 mm (H = 8.2 mm). Formed by three parts: prostate, seminal ducts and penial region; prostate elongated, bilobed, proximal lobe larger, opaque-yellowish, distal lobe translucent, striations on entire prostate; two seminal ducts connect prostate and penial region, seminal duct makes two coils right after prostate before branching into two, first seminal duct is narrower than second seminal duct, first seminal duct curls at the posterior end and stretches underneath of second seminal duct towards penial region, both seminal ducts yellowish but turn translucent at anterior end; penial region translucent with broad end, narrower towards genital opening.
Remarks. This species is often misidentified with Aliculastrum cylindricum due to their extreme similarity in shell morphology. Pease (1860) described Aliculastrum debilis as having a pellucid and fragile shell. The specimens examined during this study agree in part with this description; they have semi-translucent shells, which are, however, relatively robust. A paratype of this species (see examined material; Fig. 7) from Tahiti has a solid opaque shell, which might indicate that Pease used shells from more than one species to describe Aliculastrum debilis. Confusion around the characters to distinguish this species is well patent in the literature. For example, Pilsbry (1917) mentioned that the illustration of Aliculastrum debilis in Sowerby (1870: pl. 5, sp. 28a, b) show a projecting point at the posterior end of the columella, although such feature is not referred by Pease (1860). Carpenter (1865) mentioned that Aliculastrum debilis is identical to Atys succisa, and simply a slender version of Atys alicula. Pilsbry (1895) mentioned that Atys angustata is a synonym of Aliculastrum cylindricum but, his description of the species: "a very narrow shell with both ends thinner and strongly sinuous at the posterior ends"; resembles Aliculastrum debilis rather than Aliculastrum cylindricum. Similarly, Kay (1979) expressed doubts about a species described by Pilsbry (1917), which he named Atys cortuna that only differs from Aliculastrum debilis by possessing a wider posterior end; Kay (1979) synonymized both species under the name Atys debilis.   Aliculastrum debilis has a more elongated semi-translucent shell with deep spiral grooves at both ends, when compared with Aliculastrum cylindricum, which has a more inflated opaque shell with shallower spiral grooves at both ends. Besides, the former usually has a narrower shell towards both ends, whereas the latter has a broader anterior end compared to its posterior end. Moreover, these two species can be distinguished easily based on their anatomical features as documented above.
This species has been placed under the genus Atys by most authors although it possesses features that are different from the type species Atys naucum; for example, a cylindrical shell, gizzard plates with large ridges and complex male reproductive system with two seminal ducts. Aliculastrum debilis has an asymmetric radula; the inner lateral tooth with strong denticulation along the outer margin appears only at the right side. This character is found also in another Aliculastrum species studied in this work (e.g. A. parallelum). Preliminary phylogenetic data (Too 2011) suggest the inclusion of this species in the genus Aliculastrum.
Material examined. Mariana Islands, Guam, 4 spcs dissected, UF 374138, H = 6.8-9.6 mm. Animal ( Fig. 1C): Body whitish-translucent, white dots scattered over the body, more dense at pallial lobe edge and ventral areas of parapodial lobes, white blotches scattered over cephalic shield; between eyes, edges of cephalic and parapodial lobes with darker pigmentation; red blotches scattered on the mantle; eyes visible.
Jaws: Present, crescent shape. Radula (Figs 8C, D): Radular formula at mid-point 27 x 12.1.1.0.12; median tooth with broad base, triangular central cusp with thinner membrane-like structure on both sides, central cusp becomes more pointed posteriorly, pseudo-triangular cusp on both sides; inner lateral tooth presents only at right side, hook-shaped, broader base compared to outer lateral teeth, with semi-circular projection outwardly, broader than outer lateral teeth, strong denticulation along outer margin; outer lateral teeth hook-shaped, slender, with semi-circular projection outwardly, groove along the outer margin, size decreases outwardly.
Gizzard plates (Figs 8E, F): Three gizzard plates; broader at anterior part, narrower towards posterior end; 8-9 ridges, covered by tiny rods with pointed tips at both anterior and posterior sides, density of rods higher at anterior half of gizzard plate; posterior half of gizzard plate lacks rods on posterior side of ridges.
Male reproductive system ( Fig. 8G): Total length 3.4 mm (H = 8.54 mm). Formed by three parts: prostate, seminal ducts and penial region; prostate elongated, semi-translucent, faint striations at distal end, division into lobes not evident; two seminal ducts, first seminal duct whitish, narrower than second seminal duct, connects distally at a pouch close to prostate and proximally close to penial sheath, coils around second seminal duct, second seminal duct yellowish, broad, proximal part of both ducts semi-translucent; penial region elongated, semitranslucent.
Ecology. There is hardly any record on the habitat for this species. Materials examined were sampled on shallow areas up to 18 m depth.
Remarks. Aliculastrum parallelum was originally ascribed to the genus Bulla, but from very early on, authors like Sowerby (1870), Martens & Langkavel (1871), and Watson (1886) consider this species to belong on the genus Atys; later Pilsbry (1921) and Habe (1952) included it in the genus Aliculastrum.
Adams (1862), apparently unaware of Gould (1846)'s work, described a similar species as Cylichna parallela, which was collected in Tsushima, Japan (Strait of Korea; as Tsu-Sima). Comparison of the original descriptions revealed that these two species are identical and likely synonyms (Gould, 1846;Adams, 1862).
Aliculastrum parallelum does not have an ovoid inflated shell as the type species of the genus Atys (Atys naucum); moreover, the gizzard plates are also different from those of A. naucum with presence of few broad ridges (Carlson & Hoff 1999). On the other hand, Aliculastrum parallelum shares similarities with the other studied species of Aliculastrum by possessing a cylindrical robust shell, and, as in the species Aliculastrum debilis, an asymmetric radula with strongly denticulated inner lateral teeth and a male reproductive system with two seminal ducts. Moreover, preliminary phylogenetic data (Too 2011) suggest the inclusion of this species in a clade together with the other two species of Aliculastrum.
The genus Atys was first introduced by Montfort (1810) with type species Atys cymbulus Montfort, 1810. This species was considered a synonym of Bulla naucum Linnaeus, 1758 by Pilsbry (1895), and apparently even before by Sowerby (1870). Montfort (1810) referred the species to the African coast, although he did not specify the exact locality; though, the author was likely referring to the east coast of Africa, because A. naucum is only known in the Indo-West Pacific.
Species have been ascribed to this genus mostly based on shell morphology. The genus is characterized by umbilicate oval-elongate or inflated shells, with spiral grooves. The gizzard plates are covered with tiny rods and the radula has a median tooth (Bergh 1901;Lin 1997;Carlson & Hoff 1999). Species of the genus Atys are commonly found on shallow sandy bottoms in tropical and temperate regions and about 50 species have been reported in the Indo-West Pacific (OBIS 2012a) (see Tab. 2 for diagnostic characters of species described here).

Atys multistriatus Schepman, 1913
Atys multistriata Schepman, 1913: 468, pl Shell (Figs 2E, 9A, B): Maximum height 11.75 mm; whitish; fragile, thin, semi-translucent, elongated, oval, with slightly convex sides, anterior end protruded, posterior end truncated; spire sunken, outer lip elevated slightly above the apex, aperture narrow posteriorly and broader anteriorly, columella short, slightly concave, with a fold at the base; spiral grooves throughout shell but weaken in middle part, conspicuous axial lines present, creating netlike pattern all over the shell but weaken in middle part.
Gizzard plates (Figs 9C-E): Three gizzard plates; broader at anterior part, narrower towards posterior end; 20 ridges, thick, become crescent-shaped towards both ends, middle ridges inverted V-shaped, ridges covered by single rows of tiny rods with pointed tips along top edge, both anterior and posterior sides of ridges smooth.
Male reproductive system (Fig. 9F): Total length 3 mm (H = 6.27 mm). Formed by three parts: prostate, seminal duct and penial region; prostate single-lobed, ovoid, translucent; long seminal duct connects the prostate to penial region, about four times the length of prostate, opaque-yellow; penial region cylindrical-elongated, about half of the length of seminal duct, slightly broader than seminal duct, semi-translucent.

Key references
Pilsbry (1895) Pease (1868) Pilsbry (1895) Remarks. This species has a conspicuous reticulated sculpture on the shell, which is uncommon among haminoeids species. This feature can also be seen in Schepman's (1913: pl. 32, fig. 2a, b) illustration of the holotype. Jaws and radula could not be successful prepared for SEM and descriptions are based on Carlson & Hoff (2000). According to the latter authors, this species possesses a bilobed median tooth with fine denticulation. This feature is known in the Mediterranean and eastern Atlantic species Atys macandrewii (Martinez & Ortea, 1998) and was found in the new species here described and named Atys pittmani. The shell of Atys multistriatus and its anatomy differs from the type species Atys naucum. The disparity of shell shapes and anatomies across Atys species hints that the genus may not be monophyletic. Preliminary molecular phylogenetic results (Too 2011) point in this direction, but a generic splitting of Atys will require the use of a broader taxon sampling; therefore, we refrain to do it at this stage.   Etymology. We name this species after Cory Pittman, a chief collaborator and provider of specimens from the Hawaiian Islands. This also intends to honour his brilliant and dedicated work on the taxonomy and diversity of heterobranch gastropods of Hawaii.
Gizzard plates (Figs 10G, H): Three gizzard plates; long and narrow; 22-28 ridges, semi-circular, pseudorachis presents, ridges covered by single rows of tiny rods with pointed tips along top margin, both anterior and posterior sides of ridges smooth.
Ecology. Mud flat or on algae Halimeda; up to 10 m deep. Geographical distribution. the Philippines and Maui, Hawaii (present study).
Remarks. Shells of this species have spiral grooves at both ends interconnected with light axial lines throughout shell, a feature also found in Atys multistriatus (here studied), Atys dactylus and Atys jeffreysi, the latter two species from the Atlantic Ocean. Live animals of both Atys multistriatus and Atys pittmani are highly similar. Whereas in Atys multistriatus the white dots visible through the shell in the dorsal part of the mantle form compact clusters, in Atys pittmani those are separated and sparse apart intermingled with red dots. Also the reticulated pattern in the shell is conspicuous in Atys multistriatus whereas in Atys pitttmani is very light almost inconspicuous. Anatomically they possess distinct male reproductive systems; Atys pittmani has an elongated and distally broader prostate and shorter seminal duct. Additionally, we have evidence from preliminary molecular phylogenetic analyses that confirm the different identities of these two species (Too 2011).
Both specimens examined of Atys pittmani have identical gizzard plates and male reproductive systems, but the radula showed some variability; the specimen from Hawaii had rounded-triangular rachidian teeth whereas, the specimen from the Philippines has broader bilobed rachidian teeth. In both specimens the rachidian teeth were denticulate along the top edge.  Animal (Fig. 1F): Body whitish-opaque, dark dots scattered over the body, abundant red blotches on the mantle; eyes visible.
Jaws: Present, crescent shape. Radula (Figs 11B, C): Radular formula at mid-point 25-28 x 7-6.1.6-7; median tooth with broad base, triangular central cusp with membrane-like structure on both sides, shorter triangular lateral cusps present; outer lateral teeth hook-shaped, base with rectangular projection outwardly, grooves along both outer and inner margins, size decreases outwardly. There is no differentiation between inner and outer lateral teeth.
Gizzard plates (Figs 11D, E): Three gizzard plates; long and narrow; 21-31 ridges on each side of pseudorachis, V-shaped, ridges covered by single rows of tiny rods with pointed tips along top edge of ridge, both anterior and posterior sides of ridges smooth.
Male reproductive system (Fig. 11F): Total length 1.5 mm (H = 6.4 mm). Formed by three parts: prostate, seminal duct and penial region; prostate elongated-ovoid, bilobed, proximal lobe larger and opaque-yellowish, striations on proximal lobe sometimes present, distal lobe semi-translucent, creamy-white; prostate inserts laterally at the beginning of posterior part of seminal duct, seminal duct broad, anterior part semi-translucent, posterior part opaque-yellowish; penial region elongated, translucent, about same length as seminal duct, slightly narrower than seminal duct.
Remarks. Shells of this species vary from thin and fragile (Pease 1860) to slightly thick but always semitranslucent. Pilsbry (1895) mentioned that Atys semistriatus is identical to Atys ehrenbergi Issel, 1869, which is a fossil found in the Red Sea. The con-specificity of these species remains to be confirmed. This species possesses an ovoid inflated shell, a feature shared with the type species Atys naucum, but its gizzard plates, radula and male reproductive system have different structure and arrangement (Bergh 1901;Lin 1997;Carlson & Hoff 1999).   = 11-20, posterior = 11-16) Step-like spiral grooves at both ends (anterior = 11, posterior = 11), faint whitish band at middle part -Umbilicus ? ?

Jaws
Elongate; jaw rodlets with multiple denticles Animal (Fig. 1G): Body whitish-translucent, white dots scattered over the body, more dense on edges and mid part (between mouth and eyes) of cephalic shield, forming light yellowish blotches on the mantle, dark dots scattered over the parapodial lobes; eyes visible, inserted on unpigmented periocular areas.
Jaws: Present, crescent shape. Radula (Figs 13D-G): Radular formula at mid-point 23 x 6.1.6; median tooth bilobed with broad base, and conspicuous denticulation along edge, shorter triangular lateral cusps present; outer lateral teeth hook-shaped, broad base with semi-circular projection outwardly, groove along inner margin, weak denticulation along outer margin, size decreases outwardly. There is no differentiation between inner and outer lateral teeth.
Gizzard plates (Figs 13H, I): Three gizzard plates; long and narrow; 18 ridges on each side of pseudo-rachis, ridges covered by single rows of tiny rods with pointed tips along top edge of ridges, both anterior and posterior sides of ridges smooth.
Remarks. This species has a bulloid shell more elongated than Atys semistriatus. The colour patterns of Atys semistriatus and Atys ukulele nov. sp. are distinct. The former has large conspicuous red blotches in the mantle and dark spots scattered over the cephalic shield, whereas Atys ukulele has a mantle pigmented with faint, almost inconspicuous yellowish blotches and a cephalic shield with white dots along the edges and between the eyes. Moreover, Atys ukulele has a distinct radular median tooth, slightly bilobed with the presence of conspicuous denticulation along the margin. The reproductive system was damaged during dissection hindering comparison with Atys semistriatus.

Genus Diniatys Iredale, 1936
Type species: Bulla dentifera Adams, 1850 This genus was originally named Dinia by H. and A. Adams (1854) as a subgenus of Atys. It has been placed as a subgenus of Cylichna in Scaphandridae (Thiele 1931;Maes 1967), or as a genus of Scaphandridae (Pilsbry 1921) and Haminoeidae (Habe 1952;Burn 1978). Since Dinia was preoccupied by a group of lepidopteran insects (Walker 1854), Iredale (1936) introduced the new generic name Diniatys with the type species Diniatys dentifer, which was originally described as Bulla dentifera (Adams 1850).
The traditional diagnostic character of the genus is the tooth-like projection at the end of columella. Shells are usually ovoid and broad with fine spiral grooves and without umbilicus (Burn 1978). Three species were described in the Indo-West Pacific: D. dentifer (Adams, 1850), D. monodonta (Adams, 1850) and D. truncatula (Schepman, 1913) (Burn 1978;Carlson & Hoff 2003;Qi 2004;Gosliner et al. 2008). According to Schepman (1913), D. truncatula was found at a depth of 522 m in the Sulu Sea off the Philippines (see Tab. 3 for diagnostic characters of species described here).
Gizzard plates (Figs 15A, B): Three gizzard plates; broad, almost equal size from anterior to posterior, 11-13 ridges, rachis conspicuous, single rows of rods with pointed tips along top edge of ridges, anterior side of ridges and top side of rachis covered by tiny rods with pointed tips, posterior side of ridges smooth, density of rods increases posteriorly.
Male reproductive system (Fig. 15C): Total length 4.6 mm (H = 3.5 mm). Formed by three parts: prostate, seminal duct and penial region; prostate elongated, bilobed, proximal lobe larger, semi-translucent, distal lobe opaque-yellowish; long and thin seminal duct connects prostate and penial region, anterior part of seminal duct narrower and translucent, coils into a loop before inserting penial region; penial region elongated, semi-translucent, about half of length of seminal duct, a narrower duct is observed within.
Ecology. Associated with cyanobacteria, particularly Lyngbya, on rock reef flats and beds of Halimeda spp. at the depth of up to 21 m present study).
Jaws: Present, crescent shape. Radula (Figs 16D, E): Radular formula at mid-point 30-36 x 8-6.1.6-8; median tooth at anterior part of radula semi-circular and more pointed at posterior part; outer lateral teeth hook-shaped, grooves along both outer and inner margins, size increases outwardly but outermost tooth smallest.
Gizzard plates (Figs 16F, G): Three gizzard plates; widest in the middle, narrower towards both ends, 14-15 ridges, V-shaped, rachis conspicuous, top edge of ridges and rachis covered by tiny rods with pointed tips, both anterior and posterior sides of ridges smooth.
Male reproductive system (Fig. 16H): Total length 4 mm (H = 6.1 mm). Formed by three parts: prostate, seminal duct and penial region; prostate single-lobed, elongated, opaque-yellow; long and thin seminal duct connects prostate and penial region, translucent, slightly coils at both ends; penial region elongated, lightyellowish, about half of length of seminal duct.
Geographical distribution. the Philippines, Indonesia, Papua New Guinea, Guam, Hawaii present study).
Remarks. This species has been subjected to taxonomic confusion. Schepman (1913) named it Haminoea dubia based on features of the gizzard plates and outer lateral teeth. Carlson & Hoff (2003) placed it provisionally in the genus Diniatys and Gosliner et al. (2008) named this species Haminoea sp. 2. Shells of this species displayed a strongly calcified callus at the end of the columella folding outwardly, which is distinct from the tooth-like projection at the end of columella in Diniatys dentifer. In addition, this species also shows differences in the gizzard plates and radula compared to Diniatys dentifer. The median tooth in D. dubia is semi-circular, whereas in D. dentifer it has a sharp triangular central cusp with smaller triangular cusps at both sides. Gizzard plates of this species display single rows of tiny rods along the top edge of ridges, whereas the latter possesses tiny rods on both top edge and anterior side of ridges. On the other hand, both species possess male reproductive systems with long and fine seminal duct and elongated narrow penial region. Preliminary molecular phylogenetic analyses (Too 2011) further support the inclusion of this species in the genus Diniatys.
Genus Liloa Pilsbry, 1921 Type species: Bulla curta Adams, 1850 Pilsbry (1921) introduced Liloa as a subgenus of Haminoeidae with type species Haminoea curta tomaculum Pilsbry, 1917. According to Pilsbry (1917), this species has a narrower shell compared to Bulla curta described by Adams (1850). Habe (1952) considered both species to be synonyms and gave Liloa genus status in the family Haminoeidae. Pilsbry (1921) stated that species of the genus Liloa possess narrow shells with spiral grooves throughout but some authors claimed that some species only have spiral grooves at the ends of the shell (Habe The species Liloa curta has been either ascribed to the genus Liloa (e.g. Habe 1952;Qi 2004) or to the genus Atys (e.g. Gosliner et al. 2008). However, this species possesses both shell and anatomical features that are different from the type species Atys naucum. Liloa curta has unique gizzard plates, which have 27-42 ridges, with pointed rods along the top edge and smaller pointed rods densely covering both anterior and posterior sides of ridges. The male reproductive system of this species is also different from other haminoeids. It possesses two seminal ducts interconnected at the entrance of a translucent pouch showing a yellowish mass content. The first seminal duct has a hook-like posterior end, which might be a synapomorphy of the genus Liloa.
Gizzard plates (Figs 19A,B): Three gizzard plates; almost equal size from anterior to posterior, 10-11 ridges, covered by rods with pointed tips along top edge of ridges, dense tiny rods with pointed tips on both anterior and posterior sides of ridges, gaps between ridges smooth.
Male reproductive system (Fig. 19C): Total length 4.2 mm (H = 10 mm). Formed by three parts: prostate, seminal ducts and penial region; prostate oval, bilobed, proximal lobe smaller, opaque-brownish, distal lobe lightyellowish; translucent duct connects prostate to creamy-yellowish striated (?)glandular region, which opens distally to first seminal duct that possesses hook-like posterior end, and proximally opens to second seminal duct, translucent, coils twice before connecting to penial region; penial region oval, translucent, with convoluted opaqueyellowish inner glandular duct connecting to genital opening.
Remarks. There are a few conflicting features about the description of this species. Some authors referred to Liloa porcellana with spiral grooves only at both ends of shell (Pilsbry 1895;Habe 1952;Lin 1997). However, the original description states that spiral grooves are more visible at both ends, which does not imply that the middle part of the shell is smooth (Gould 1859). The study of the holotype (USNM 1357) confirmed the presence of spiral grooves throughout the shell but they are in fact faint in the middle part of the shell. Larger specimens that we examined (H ≥ 4.2 mm) have spiral grooves along the entire shell, with distance between grooves decreasing towards both ends; whereas the small specimen (H = 2.8 mm) have spiral grooves only at both ends of the shell (Figs 1K-L, 2E-G). The holotype of Liloa porcellana has a narrower posterior end compared to its anterior end. However, this was not exactly the case for the shells examined during this study, but differences in shell height may explain this phenotypic difference, since none of our specimens was as large as the holotype (H = 12 mm). The anatomical features of our specimens match those described by Habe (1952).
This species can be distinguished from Liloa curta by a slender-elongated shell shape and spiral grooves that become closer towards the ends of the shell, although the latter feature may vary ontogenetically. Also, Liloa porcellana only has spiral grooves in the mid-region of the shell in adult specimens; in juveniles, those can be faint or absent. Both species have similar radula. The gizzard plates of Liloa porcellana have fewer and far apart ridges than Liloa curta where the ridges are numerous and tight together. Moreover, the male reproductive system of Liloa porcellana has a longer and twisted secondary seminal duct (Fig. 19C, sd 2) and a conspicuous duct connecting the prostate to a globose glandular region whereas in Liloa curta the prostate almost sits on top of the globose glandular region.

Discussion
The generic classification of the family Haminoeidae has been hindered by taxonomic uncertainty. Authors had ascribed species to various genera with questionable reasons or strict criteria as documented in the Results section of this work. Also species descriptions have been hampered by the lack of use of anatomical data and details of the morphology and colouration of live animals. Though some authors considered morpho-anatomical features (e.g. Rudman 1971Rudman , 1972aGosliner 1979Gosliner , 1989, the use of conchological features has traditionally dominated the taxonomy of cephalaspids worldwide (discussed in Malaquias and Reid 2008). In the tropical Indo-West Pacific the situation is no different and the problem has been acknowledged by several authors (e.g. Pease 1868; Carlson & Hoff 2000;Malaquias and Reid 2008).
Based on the combined study of live animals, external morphology, anatomy and shells, and in part aided by molecular phylogenetic data (Too 2011) we here provide new insights into the diversity of four genera of haminoeids gastropods inhabiting the tropical West Pacific and attempt to recognize morpho-anatomical synapomorphies: Aliculastrum-Species in this genus have cylindrical robust shells with spiral grooves at both ends and a thick columella. The combination of these features seems to be diagnostic of the genus. No anatomical synapomorphy could be established; A. debilis and A. parallelum share the possession of an asymmetric radula and male reproductive system with two seminal ducts, but none of these characters were found in the type species A. cylindricum. On the other hand, A. cylindricum and A. debilis are fairly identical in shell morphology, which led authors to misidentify these two species (Watson 1886;Pilsbry 1895). Aliculastrum debilis has been recently placed under the genus Atys (see Remarks section), but preliminary molecular phylogenetic analysis suggests its inclusion in the genus Aliculastrum (Too 2011).
Atys-The definition of this genus has been a matter of ongoing debate. Pilsbry (1895) expressed doubts about the taxonomic arrangement of the group and mentioned that at least two to three genera could be created based upon differences of shell morphology. Rudman (1998b) questioned the systematic arrangement of Atys and Malaquias et al. (2009b) claimed Atys to be monophyletic but only Atys curta (= Liloa) and Atys cylindricus (=Aliculastrum) were included in their phylogenetic analyses.
There are more than 50 species described under the genus Atys in the Indo-West Pacific, although most of them do not possess ovoid inflated robust shells as the type species A. naucum, but instead elongated and fragile shells. Unfortunately, specimens of the type species A. naucum were not available for anatomical dissection but this species has been extensively studied before (e.g. Bergh 1901;Lin 1997;Carlson & Hoff 1999). According to Bergh (1901), A. naucum possesses a radula with 70 rows of teeth with a triangular median tooth. While documenting similar median tooth character, Lin (1997) referred to the presence of smaller triangular cusps at both sides of the median tooth. Both Bergh (1901) and Carlson & Hoff (1999) referred that gizzard plates have a high number of fine ridges, and the latter authors mentioned the presence of tiny rods on top of ridges. Clarification of the generic status of species traditionally included in the genus Atys would require a broader study encompassing species from all biogeographic regions. However, preliminary molecular phylogenetic data (Too 2011) rendered traditional Atys paraphyletic. Until a sound phylogenetic framework is available for the relationships of haminoeidae gastropods we suggest using Atys in its traditional sense (sensu Burn & Thompson 1998).
Diniatys-Species of this genus have a strongly calcified callus at the end of columella folding outwardly that can resemble a tooth-like projection. This seems to be a synapomorphy of the genus. Anatomically, species of Diniatys have a male reproductive system with a fine and long seminal duct that is at least twice as long as the elongated penial region. This is unique among haminoeidae gastropods and can also be considered a synapomorphic trait of the genus.
Liloa-Recognized synapomorphies of the genus are the presence of spiral grooves covering the translucent shells more or less regularly spaced throughout; gizzard plates lacking rachis with ridges organized parallel to each other with pointed rods densely arranged on both anterior and posterior sides and a single row of larger pointed rods along the top margin; presence of two seminal ducts in the male reproductive system, one of them having a hook-like posterior end.