taxonID	type	description	language	source
03A487C8FFE8FFA14CDDFC11CAEBF9F4.taxon	diagnosis	Diagnosis Body oval, arched dorsally, white or ivory coloured. Cephalic shield square-oval. Shell internal, subquadrate, slightly angled dorsally. Radular formula 12 – 13 × 2.1.1.1.2. Gizzard plates (3), elongated, oval, symmetrical; internal surface, chitinous, flattened, holes or slits absent, with concentric amber and brown bands; external surface flattened. Material examined North South Sandwich Islands, SS 1 A / 30, 56 ○ 42 ′ 60.6 ′′ S, 27 ○ 1 ′ 35.8 ′′ W, 134 – 142 m depth: 1 specimen, sequenced and dissected, SIO-BIC M 13656 (3 September 2011), COI barcode MN 486291, L = 11 mm, W = 7 mm; SS 2 A / 38, 58 ○ 22 ′ 42 ′′ S, 26 ○ 17 ′ W, 134 – 260 m depth: 23 specimens, 11 sequenced and 1 dissected, SIO-BIC M 12941 (6 October 2011), L = 10 mm, W = 7 mm; SS 3 / 42, 56 ○ 42 ′ 60.6 ′′ S, 27 ○ 1 ′ 35.8 ′′ W, 103 – 221 m depth: 4 specimens, 1 sequenced and 1 dissected, SIO-BIC M 12993 (7 October 2011), barcode MN 486273, L = 15 mm, W = 8 mm. South Sandwich Islands, St. A 6 - 2: 12 specimens, 1 dissected (not sequenced), MCZ 393943 (February 1995), L = 15 mm, W = 9 mm; St. 136 - 1, 70 ○ 50 ′ 12.0 ′′ S, 10 ○ 35 ′ 24.0 ′′ W, 271 m depth: 6 specimens, 1 dissected (not sequenced), ZSM 20010079 (10 April 2000), L = 13 mm, W = 7 mm. External morphology (Fig. 2 a) Maximum L = 11 mm, W = 7 mm. Body oval, arched dorsally; white or ivory coloured. Mantle thin, translucent white. Cephalic shield oval, extending approximately half of body, slightly extended over shell; extending longitudinally from second third until posterior edge. Parapodial lobes triangular, slightly extended over shell. Foot smooth, extending from mouth to approximately three-quarters of animal. Shell (Fig. 2 b) Maximum L = 7.2 mm, W = 5.7 mm. Internal, subquadrate, white, thin, slightly angled dorsally, flattened. Periostracum thin, pellucid. Aperture almost full extension of shell, with thin parietal callus. Outer lip straight, in right angle posteriorly. Columellar wall concave. Apex superficial, umbilicated, left-sided. Growth lines marked. Radula (Fig. 2 c) Radular formula 12 – 13 × 2.1.1.1.2. Rachidian teeth not detected. Later teeth hook-shaped, inner lateral thick, with broad base, tip rounded or pointed, inner edge with faint dentition not always detected. Outer lateral teeth hook-shaped, with broad base, tip rounded. Digestive system (Figs 2 d & 3) Buccal mass very muscular. Salivary glands short, entering pharynx from posterior end, extending over crop to beginning of gizzard. Crop globose, saccular, thin-walled. Gizzard elongated, surrounded by circular muscle fibres. Gizzard plates three (maximum L = 1.5 mm, W = 0.6 mm), elongated, oval, symmetrical; internal surface, chitinous, flattened, holes or slits absent, with concentric amber and brown bands; external surface flattened (Fig. 2 e, f); spines present in gizzard (Fig. 2 d). Oesophagus thin, internally plicate. Stomach embedded in digestive gland. Digestive gland large, brownish, granulose; occupying most of viscera. Intestine rising posteriorly towards the anterior part of the shell, creating a loop, turning backwards to right side; ending in external anal papilla situated in mantle cavity. Reproductive system (Figs 2 g, h & 4) Male penial sheath short, pyriform. Penial papilla short. Ejaculatory duct displayed in an S shape, surrounded by musculature tissue. Prostate granulose, saccular, shorter than penial sheath, attached to seminal vesicle. Seminal vesicle saccular, semitranslucent, slightly smaller than prostate, containing autosperm. Female gonad orange in colour (ovules), presenting white marks (sperm), lumpy, surrounding the digestive gland posteriorly. Ampulla cylindrical, isodiametric, displayed in zigzag. Seminal receptacle oval, short, connected by a thin duct. Albumen gland (= capsule gland; Klussmann-Kolb 2001) rugose, relatively small, covering end of ampulla and seminal receptacle duct. Membrane gland bean-shaped, internally attached to mantle cavity. Mucous gland white, large, folded, extending ventrally above viscera towards left edge. Bursa copulatrix rounded, distally connected to vagina through a thin, long duct. Vagina muscular, with ample atrium. Excretory, circulatory and respiratory systems Kidney flattened, in anterior right side of viscera, attached to mantle, internally highly ramified, connected to pericardium anteriorly. Pericardial complex arranged transversally in an angle of 45 ○. Auricle thin-walled. Ventricle triangular, muscular. Aorta thick, bifurcating into two branches that run parallel to edge of shell. Ecology Occurs in sandy bottoms at depths from 4 m (this study) down to 640 m (Hain 1990). Sponge spicules, diatoms and foraminifera were found in the gut contents of the specimens dissected in this study (Fig. 5 a – c). Distribution Known from the Davis Sea and Adélie land in East Antarctica (Thiele 1912, Vicente & Arnaud 1974); South Orkney Islands, South Sandwich Islands in the Scotia Sea and Palmer Archipelago in the western Antarctic Peninsula (Powell 1951, Aldea & Troncoso 2008, Moles et al. 2021); Deception, Livingston and King George islands in the South Shetland Islands (Powell 1951, Troncoso et al. 1996, Engl 2012, Moles et al. 2021); Peter I Island, Bellingshausen Sea (Aldea & Troncoso 2008);? eastern Weddell Sea (Hain 1990, Engl 2012); and Bouvet Island (Moles et al. 2019). Remarks This species was described by Thiele (1912) based on a single shell record from the Davis Sea characterized by an almost squarish, smooth shell with growth lines, a straight outer lip and a somewhat straight base. This type of shell has been found all over Antarctica and resembles our material. Although slight intraspecific differences in the shape of the gizzard plates exist (e. g. more convex, sometimes slightly pointy, the colour on the bands), they are oval, chitinous and flattened in the interior and exterior parts, with concentric amber and brown bands on the interior side. Most records in the distribution area have been revised by Moles et al. (2019), and here we add specimens from the northern and southern South Sandwich Islands. There, we found specimens showing no remarkable morphological differences from those from the remaining areas of distribution. Overall, although molecular data recognize several lineages (Fig. 1; Moles et al. 2021), the dissected specimens from Bouvet Island, the South Shetland Islands and the South Sandwich Islands present no clear morphological differences (Moles et al. 2019; this study) and thus are retained here as a single species.	en	Peralta-Serrano, Marc, Schrödl, Michael, Wilson, Nerida G., Moles, Juan (2025): Revealing hidden diversity and cryptic speciation in Antarctic marine gastropods (Heterobranchia: Cephalaspidea). Antarctic Science (Cambridge, England) 37 (3): 154-166, DOI: 10.1017/S0954102024000385, URL: https://doi.org/10.1017/s0954102024000385
03A487C8FFEEFFA34C3DF912CF19F895.taxon	diagnosis	Diagnosis Body oval, large, arched sagittally, white nacreous coloured. Cephalic shield sub-rectangular. Shell internal, ovate-subquadrate, slightly angled dorsally, wide dorsoventrally. Radular formula 15 × 2.1.0.1.2. Gizzard plates (3) elongated, oval, ventral plate smaller than dorsal ones; internal surface highly chitinous, convex, holes or slits absent; external surface flattened, with concentric amber and dark brown bands. ZooBank registration urn: lsid: zoobank. org: act: 2 B 7 C 5 D 1 E-C 187 - 47 CE- 8897 - 250 E 481 - 2071 F. Etymology The species’ name derives from its depth distribution encompassing the abyssal plain from ~ 3000 to 4550 m depth. Type locality Transition Weddell Sea to south of South Sandwich Islands, 2892.8 – 4547.6 m depth. Material examined Transition Weddell Sea to south of South Sandwich Islands, St. PS 61 / 1384, 62 ○ 57 ′ 48 ′′ S, 27 ○ 52 ′ 8.4 ′′ W, 4547.6 m depth: 1 specimen, ZSM 20021046 (holotype; 16 March 2002), COI barcode MN 486283, L = 27 mm, W = 10 mm. North Elephant Island, St. PS 61 / 046 - 7, 60 ○ 39 ′ 11.4 ′′ S, 53 ○ 56 ′ 51 ′′ W, 2892.8 m depth: 1 specimen, sequenced, ZSM 20021211 (paratype; 30 January 2002), COI barcode MN 486284, L = 5 mm, W = 2 mm. Northwest Bouvet Island, South Atlantic Ocean, St. PS 71 / 013 - 15, 52 ○ 2 ′ 31.8 ′′ S, 0 ○ 0 ′ 36 ′′ E, 2996 m depth: 2 specimens, 2 sequenced, ZSM 20081179 (paratypes; 6 December 2007), COI barcode MN 486285, L = 10 mm, W = 5 mm, COI barcode MN 486286, L = 8 mm, W = 3 mm; St. PS 79 / 081 - 18, 52 ○ 21 ′′ S, 10 ○ 1 ′ 28 ′′ E, 3705 – 3757 m depth: 1 specimen, ZSM 20130151 (paratype; 20 January 2012), COI barcode MN 486287, L = 16 mm, W = 5 mm; PS 79 / 081 - 17, 52 ○ 11 ′′ S, 10 ○ 43 ′′ E, 3743 – 3763 m depth: 1 specimen, dissected, ZSM 20130153 (paratype; 20 January 2012), COI barcode MN 486288, L = 27 mm, W = 11 mm. External morphology (Fig. 6 a) Maximum L = 27 mm, W = 11 mm. Body oval, large, arched sagittally. Shell slightly wide, white nacreous coloured; surrounded by translucent white thin mantle. Cephalic shield sub-rectangular, representing 45 % body extension, slightly over shell; posteriorly slightly bilobed. Parapodia triangular, extended over shell. Foot smooth, extending from mouth approximately three-fifths of the animal. Shell (Fig. 6 b) Maximum L = 12.6 mm, W = 8.6. Internal, ovate-subrectangular, white, thin, slightly angled dorsally, wide dorsoventrally. Periostracum thin, pellucid. Aperture almost representing full extension of shell. Columellar wall concave. Parietal callus thin; outer lip directed towards body whorl, extending downwards. Body whorl wide. Apex bulky, umbilicated, sunken, left-sided. Growth lines marked. Radula (Fig. 6 c) Radular formula 15 × 2.1.0.1.2. Rachidian not detected. Lateral teeth hook-shaped, inner lateral thick, with broad base, tip rounded or pointed, inner edge with very faint denticulation. Outer lateral teeth hook-shaped, with broad base, tip rounded or pointed. Digestive tract (Fig. 6 e) Buccal mass highly muscular. Salivary glands long, connected ventrally, entering pharynx from dorsal end, extending under pharynx, going up over crop to beginning of gizzard. Crop globose, saccular, thin walled. Gizzard elongated, surrounded by circular muscle fibres. Gizzard plates (3; maximum L = 1.5 mm, W = 0.8 mm), elongated, oval, ventral plate smaller than dorsal ones; internal surface highly chitinous, convex, translucid, holes or slits absent; external surface flattened, with concentric amber and dark brown bands (Fig. 6 e, f); spines present in gizzard (Fig. 6 d). Male reproductive system (Fig. 6 g, h) Penial sheath short, pyriform. Penial papilla small, ~ 4 mm in length. Ejaculatory duct surrounded by musculature tissue. Prostate granulose, saccular, shorter than penial sheath, displayed attached to seminal vesicle. Seminal vesicle saccular, slightly smaller than prostate, containing autosperm. Ecology Found in abyssal plains from 2892.8 to 4547.6 m depth. Sponge spicules and foraminifera were found in the gut contents of the single specimen studied (Fig. 5 d – f). Distribution Known from the South Atlantic Antarctic Ridge, from the vicinities of Bouvet Island to Elephant Island. Remarks The new species is differentiated from its counterparts (i. e. A. alata, A. amundseni, A. apertissima, A. easmithi, A. falklandica, A. gibba, A. malaquiasi sp. nov.) by the larger size and wider shell. The shell has a large columellar callus and presents a greater length / width ratio and larger body compared to the other species. In addition, the dark brown, highly chitinous, small gizzard plates, pronouncedly convex internally and flattened externally, are characteristic of this species. The bathymetric range of A. abyssalis sp. nov. encompasses bathyal and abyssal depths in the South Atlantic Antarctic Ridge, where no previous records of any other species are found. The most closely related species is A. amundseni, known from 196 to 1048 m depth in the Weddell Sea.	en	Peralta-Serrano, Marc, Schrödl, Michael, Wilson, Nerida G., Moles, Juan (2025): Revealing hidden diversity and cryptic speciation in Antarctic marine gastropods (Heterobranchia: Cephalaspidea). Antarctic Science (Cambridge, England) 37 (3): 154-166, DOI: 10.1017/S0954102024000385, URL: https://doi.org/10.1017/s0954102024000385
03A487C8FFECFFAD4F7CF8E1C808F8B4.taxon	diagnosis	Diagnosis Body oval, large, arched in sagittal plain, white or ivory coloured. Cephalic shield oval. Shell internal, subquadrate, slightly angled dorsally, flattened. Radular formula 12 × 2.1.0.1.2. Gizzard plates (3) elongated, oval, ventral plate smaller than dorsal ones; internal surface, chitinous, slightly convex on one side, holes or slits absent, with concentric amber and dark brown bands; external surface highly convex, sometimes asymmetrically pointy dorsally. ZooBank registration urn: lsid: zoobank. org: act: 963 E 806 A-B 353 - 472 D-A 3 E 9 - 29 D 690 - CB 00 B 7. Etymology This species is named in honour of Dr Manuel António E. Malaquias for his contribution to the systematics of cephalaspidean molluscs. Type locality Bransfield Strait, 150 – 247 m depth. Material examined Bransfield Strait, St. BS 1 / 86, 62 ○ 52 ′ 20.7 ′′ S, 57 ○ 11 ′ 32.5 ′′ W, 150 – 247 m depth: 2 specimens, sequenced and dissected, SIO-BIC M 17786 (holotype; 24 October 2011), L = 9.6 mm, W = 5.4 mm, COI barcode MN 486290, SIO-BIC M 17787 (paratype; 24 October 2011), L = 6 mm, W = 4 mm. External morphology (Fig. 7 a) Body oval, arched in sagittal plane; maximum L = 8 mm, W = 4.5 mm, white or ivory coloured; surrounding translucent white thin mantle. Cephalic shield oval, half of body extension, slightly over shell; central grove slightly marked, last two-thirds extension. Parapodia triangular, slightly extended over shell; gill visible from above. Foot smooth, extending from mouth approximately three-quarters of the animal. Shell (Fig. 7 b) Maximum L = 6.6 mm, W = 5.3. Internal, subquadrate, white, thin, slightly angled dorsally, flattened. Periostracum thin, pellucid. Aperture almost full extension of shell, with thin, parietal callus. Outer lip straight, in right angle on posterior side. Columellar wall concave. Apex superficial, umbilicated, left-sided. Growth lines marked. Radula (Fig. 7 c) Radular formula 12 × 2.1.0.1.2. Rachidian not detected. Lateral teeth hook-shaped, inner lateral thick, with broad base, tip rounded, inner edge without denticulation. Outer lateral teeth hook-shaped, with broad base, tip rounded or pointed. Digestive tract (Fig. 7 e) Buccal mass highly muscular. Salivary glands short, entering pharynx from posterior end, extending over crop to beginning of gizzard. Crop globose, saccular, thin walled. Gizzard elongated, surrounded by circular muscle fibres. Gizzard plates (3; maximum L = 1.5 mm, W = 0.6 mm) elongated, oval, symmetrical; internal surface chitinous, slightly convex on one side, holes or slits absent, with concentric amber and brown bands; external surface highly convex, sometimes asymmetrically pointy dorsally (Fig. 7 e, f); spines present in gizzard (Fig. 7 d). Male reproductive system (Fig. 7 g, h) Penial sheath short, pyriform. Penial papilla small. Ejaculatory duct surrounded by musculature tissue. Prostate granulose, saccular, shorter than penial sheath, displayed attached to seminal vesicle. Seminal vesicle saccular, semitranslucent, slightly bigger than prostate, containing autosperm. Ecology Found between 150 and 247 m depth. Sponge spicules, diatoms and foraminifera were found in the gut contents of the single specimen dissected in this study (Fig. 5 g – i). Distribution Only known from the Bransfield Strait. Remarks Although not closely related phylogenetically to A. alata and A. gibba, the new species can hardly be differentiated from them externally. Only the shape of the gizzard plates, being highly convex and pointy dorsally, and a slightly more rounded shell are differential characters compared to the ones from A. alata and A. gibba. These are characters subject to intraspecific variation, thus more specimens are needed to further explore these differences. Unfortunately, only two specimens have been collected so far. Its known distribution also seems to overlap with A. alata and A. gibba, matching the same bathymetrical distribution, indicating that this species may coexist in the same locality.	en	Peralta-Serrano, Marc, Schrödl, Michael, Wilson, Nerida G., Moles, Juan (2025): Revealing hidden diversity and cryptic speciation in Antarctic marine gastropods (Heterobranchia: Cephalaspidea). Antarctic Science (Cambridge, England) 37 (3): 154-166, DOI: 10.1017/S0954102024000385, URL: https://doi.org/10.1017/s0954102024000385
