Edentellina singaporensis, (Jensen, 2015)

EdenTellina singaporensis (Jensen, 2015)

( Figs 4Q, R, 24D, E, 31–33)

Berthelinia singaporensis Jensen 2015: 233–5 View in CoL , figs 1F, 5D, E, 6, 7. Type locality: Chek Jawa , Singapore.

Type material

Berthelinia singaporensis , Holotype, complete specimen 4 mm long ( ZRC MOL.5789).

Additional material examined

Port Dickson , Malaysia, one specimen 4.2 mm long (shell), leg. L. Wong, isolate JC87B ( CPIC 02538 ) . Johor, Malaysia, one specimen 4 mm long (shell), leg. L. Wong, isolate JC88A ( CPIC 02539 ) ; one specimen 4 mm long (shell), leg. L. Wong, isolate JC88B ( CPIC 02539 ) .

Description

Body elongate, ≤ 6.5 mm in length, completely retractable inside of shell. Body colour bright green, with numerous opaque white spots concentrated on the dorsal side of the head ( Fig. 24D, E). Head elongate, with eye spots located on dorsal swelling near centre. Rhinophores enrolled, green, with small white speckles concentrated on dorsal side. Oral tentacles short, green, edged in white. Foot lighter than rest of animal, edged in white. Mantle visible through shell, brownish-green, covered with small white dots, more concentrated at the edge. Foot extending to posterior end of shell, forming a small triangular projection.

Shell up to 4.2 mm × 2.7 mm in size, tallest point near anterior end, widest point near ventral margin; shell shape ovoid, elongate, dorsal margin regularly curved, ventral margin more flatened; anterior margin convex, irregularly curved, slightly more flatened dorsally, posterior margin narrowing gradually, forming a nearly triangular, elongate shape, with round end ( Fig. 31E, F). Protoconch on lef valve of teleoconch, ~150 µm long, with 1.5 whorls ( Fig. 31I). Hinge on dorsal margin of shell formed by flatened, corrugated, nearly straight area, margin on both valves; condyloid tooth not clearly differentiated, on right valve at posterior end of hinge, and triangular, fossete-like hinge socket on lef valve, at posterior end of hinge ( Fig. 31G, H). Shell translucent, with no visible markings or spots on shell surface, and sof parts of body visible through it ( Fig. 32A–D).

Adductor muscle located closer to anterior end of shell, in slightly below widest point ( Fig. 32A), connected to narrow and elongate head retractor muscle ( Fig. 32B). Adductor scar visible on shell ( Fig. 31F). Gill large, occupying two-thirds of body, posterior to adductor muscle, covering dorsal portion of digestive gland. Pharyngeal bulb with a short pharyngeal appendage dorsally. Penis elongate; distal end pointed, with a short stylet ( Fig. 32E); proximal end wider, with a strong retractor muscle atached ( Fig. 32D).

Radula with 42 teeth in descending limb and 8 fully formed teeth + 1 ghost tooth in ascending limb, in 4-mm-long specimen from Johor, Malaysia (isolate JC88B, CPIC 02539 ) ( Fig. 33A). Active tooth saber-shaped, ~140 μm long, with sharp, pointed tip; blade elongate, with central row of numerous long, delicate denticles; base short, slightly curved ( Fig. 33B). Ascus ~50 μm long, containing one long, rod-shaped pre-radular tooth and ~10 intermediate teeth ( Fig. 33C) .

Biology

Tis species feeds on at least five species, including Caulerpa racemosa , Caulerpa lentellifera J. Agardh, 1837, Caulerpa serrulata (Forsskål) J. Agardh, 1837, C. sertularioides , and Caulerpa cf. lamourouxii (Turner) C. Agardh, 1817 , without a particular preference ( Wong and Sigwart 2019). Te egg masses are flat and band-shaped, containing a mean of 46.6 eggs per egg mass ( N = 50 clutches; range = 8–108), with an egg diameter of ~83 µm and capsule size ~330 µm × 250 µm. Te larvae hatch as pediveligers, with a shell width of 244.11 µm ± 12.29 μm ( N = 30) ( Jensen and Ong 2018, Wong and Sigwart 2019).

Range

Singapore (Jensen 2015), Malaysia ( Wong and Sigwart 2019; present paper).

Remarks

Jensen (2015) introduced the name Berthelinia singaporensis Jensen, 2015 based on several specimens collected in Singapore. Jensen (2015) described the shell as broadly rounded anteriorly, more narrowly rounded posteriorly, with the highest point in the anterior half, in front of protoconch; protoconch having 1.5 whorls and located in posterior half of lef valve, tilted towards right valve; hinge with a fork and a cardinal tooth on each valve. Te live animal was described as uniformly bright green, protoconch white, rhinophoral tips doted in white, some specimens having white dots continuing down the rhinophores (Jensen 2015). Jensen (2015) indicated that the radula was composed of 10 or 11 fully formed teeth (and one ghost tooth) in the ascending limb and 26–30 teeth in the descending limb plus 1 rod-shaped preradular tooth; the radular teeth were blade-shaped, with a row of hair-like denticles along each side, tips with a small knob but not bifid. Finally, the penis was described as having a flexible stylet with peculiar lateral flanges.

In this study, we examined specimens from localities in Malaysia adjacent to or very close to Singapore, which match the characteristics of the original description of B. singaporensis . Tese specimens are genetically distinct from other species examined herein. Because of the morphological similarities of the Malaysian specimens to B. singaporensis and the proximity to the type locality, they are here assigned to this species. Moreover, the phylogenetic analyses confirm our specimens of B. singaporensis group with other species of Edentellina , and therefore the species is transferred to Edentellina .

Subfamilp Gougerotiinae Le Renard, 1980 View in CoL

Genus Gougerotia Le Renard, 1980 View in CoL

† Gougerotia Le Renard 1980: 24 View in CoL . Type species: Gougerotia orthodonta Le Renard, 1980 View in CoL , by original designation.

Diagnosis

Shell thick, oval to elongate in lateral view; anterior margin rounded, narrowing into sharper posterior margin; shell tallest point near anterior end; right valve larger, taller than lef valve; pseudo-hinge with conspicuous condyloid tooth on right valve inserting into deep socket under protoconch in lef valve, spliting hinge into two sections; protoconch conspicuous, on lef valve, towards posterior third of shell; adductor muscle scar subcentral.

Species list

† Gougerotia orthodonta Le Renard 1980: 23–5 View in CoL , fig. 12. Type locality: Chaussy , Val d’Oise , France and Mercin, Aisne, France (Middle-Late Eocene) .

Genus Hemiplicatula Deshapes, 1861 View in CoL

† Hemiplicatula Deshayes 1861: 128 View in CoL . Type species: Placuna solida Melleville, 1843 View in CoL , by monotypy.

Diagnosis

Shell thick, oval to elongate in lateral view; anterior margin rounded, narrowing into sharper posterior margin; shell tallest point near centre; valves similar in size; pseudo-hinge with elongate condyloid tooth on right valve inserting into deep socket in lef valve, spliting hinge into two sections; adductor muscle scar subcentral.

Species list

† Placuna solida Melleville 1843: 89–90 View in CoL , pl. 1, figs 6, 7. Type locality: Laon , France (Early Eocene) .

† Hemiplicatula pissarroi Cossmann 1905a: 154–5 View in CoL , pl. 8, figs 10, 11. Type locality: Bois-Gouët , Loire-Atlantique, France (Early Eocene) .

Genus Saintia de Raincourt, 1877 View in CoL

† Saintia de Raincourt 1877: 329 View in CoL , pl. 4, fig. 9. Type species: Saintia munieri de Raincourt, 1877 View in CoL , by monotypy.

Diagnosis

Shell thick, oval to round view; anterior and posterior margins rounded, similar in height; shell tallest point near centre; pseudo-hinge with deep socket in lef valve, spliting hinge into two sections; adductor muscle scar subcentral.

Species list

† Saintia munieri de Raincourt 1877: 329 View in CoL , pl. 4, fig. 9–9b. Type locality: Hérouval , France (Early Eocene) .