Edentellina limax, (Kawaguti & Baba 1959)

McCarthy-Taylor, Jennifer B., Krug, Patrick J., Muro, Sandra, Vendeti, Jann, Maestrati, Philippe, Wong, Nur Leena W. S., Gosliner, Terrence M. & Valdés, Ángel, 2025, Te slug within the bivalve: molecular and morphological systematics of the family Juliidae (Gastropoda: Panpulmonata: Sacoglossa), Zoological Journal of the Linnean Society 204 (2) : -

EdenTellina limax ( Kawaguti & Baba 1959)

( Figs 12–14)

Tamanovalva limax Kawaguti and Baba 1959: 179–180 , figs 1–10. Type locality: vicinity of the former Tamano Marine Laboratory , Okayama University, by the Great Seto Bridge, Japan.

Type material

Unknown (not reported by Higo et al. 1999). Additional material examined

Tamano Bay , Okayama Prefecture, Japan, 22 August 1960, two specimens (dry) 3.4 mm long, leg. S. Kawaguti ( CASIZ 201960 ) ; three valves 6–6.5 mm long, leg. S. Kawaguti ( CASIZ 201959 ) ; two specimens (dry) 4.5–5 mm long + 33 veliger shells, leg. S. Kawaguti ( CASIZ 201957 ) ; 75 veliger shells, leg. S. Kawaguti ( CASIZ 201958 ) ; 10 veliger shells, leg. S. Kawaguti ( CASIZ 201956 ) . Mukaishima Island , Hiroshima Prefecture, Japan, 13 April 1960, one specimen (wet) 2 mm long (shell), leg. K. Baba ( MV F23063 ) . Description

Live animals not examined, illustrated by Abe (1964: pl. 6, fig. 20) and Hamatani (2000: pl. 379; 2017: pl. 405) as having an elongate body, ≤ 10 mm in length. Body colour pale green, lacking white speckles. Head elongate, with eye spots located on dorsal swelling near centre. Rhinophores enrolled, green, with a few white speckles. Oral tentacles short, green. Foot lighter than rest of animal. Mantle visible through shell, dark green, covered with large, whitish-beige patches, variable in size; edge surrounded by alternating opaque white patches composed of densely arranged speckles; adductor muscle visible through shell as white patch. Foot forming small triangular projection, not extending beyond posterior end of shell.

Shell up to 6.5 mm × 4.4 mm in size, tallest point near anterior margin, widest point near ventral margin; shell shape ovoid to quadrangular, dorsal margin regularly curved with distinct apex, ventral margin more flatened; anterior margin convex, irregularly curved, slightly more flatened dorsally, posterior margin shorter, narrowing gradually ( Fig. 12G, H). Protoconch on lef valve of teleoconch, ~150 µm long, with 1.5 whorls ( Fig. 12K). Hinge on dorsal margin of shell, formed by flatened, corrugated, nearly straight area, margin on both valves; low, oval condyloid tooth on right valve, triangular, fossete-like hinge socket on lef valve, at posterior end of hinge ( Fig. 12I, J). Shell translucent, with no visible markings or spots on shell surface, and sof parts of body visible through it ( Fig. 12A–F).

Adductor muscle located in line with highest point of shell, slightly below widest point ( Fig. 13A), connected to narrow and elongate head retractor muscle. Adductor scar visible on shell ( Fig. 12H). Gill large, occupying almost height of body, posterior to adductor muscle, covering anterior portion of digestive gland. Penis short, triangular; distal end pointed, with conical stylet ( Fig. 13C); proximal end of penis wider, with two strong retractor muscles atached and tubular deferent duct ( Fig. 13B). Pharyngeal bulb as wide as tall ( Fig. 13D).

Radula with 28 teeth in descending limb and 6 fully formed teeth + 1 ghost tooth in ascending limb, in 4.5-mm-long specimen from Tamano Bay, Japan ( CASIZ 201957) ( Fig. 14A). Active tooth ~135 μm long, with sharp, pointed tip; blade elongate, with central row of numerous long, delicate denticles; base short, curved ( Fig. 14B). Ascus containing one long, rod-shaped pre-radular tooth plus five intermediate teeth ( Fig. 14C).

Biology

According to Kawaguti and Yamasu (1960), E. limax feeds on Caulerpa okamurai Weber-van Bosse in Okamura, 1897 and lays egg masses with a small number of eggs (11–470); each egg within an ovoid capsule of 250 µm × 270–380 µm on average. And according to Yamasu (1969) it has lecithotrophic development, very similar to that of E. singaporensis (Jensen & On, 2018; Wong and Sigwart, 2019).

Range

Wakayama Prefecture and Inland Sea, Japan ( Kawaguti and Baba 1959, Hamatani 2017).

Remarks

Kawaguti and Baba (1959) described, for the first time, live animals of Juliidae under the new name Tamanovalva limax Kawaguti & Baba, 1959 . For the original description, Kawaguti and Baba (1959) had access to> 200 specimens collected near the former Tamano Marine Laboratory, Okayama University, Japan. Unfortunately, they did not designate a holotype, and we have been unable to locate the type series. Kawaguti and Baba’s (1959) description included accounts of the characteristics of the live animals and features of the internal anatomy and the shell, all illustrated in great detail. Kawaguti and Baba (1959) described the shell as translucent yellowish white, thin, elongate-oval, narrowing posteriorly, with the umbo behind the mid-length, hinge with no teeth. Te colour of live animals was described as deep green, with opaque white dots on the rhinophores and head, mantle margin sparsely spoted with white and dark brown, and the deep green colour of the mantle showing through the shell. Other characteristics included having stout, grooved rhinophores, small foot corners, a raised area where the eyes are located, and a short posterior end of the foot, not extending beyond the shell. Te radula was formed of 35 blade-like teeth finely denticulate on both edges.

Prabhakara Rao (1965) reported four specimens of bivalved gastropods from India found on Caulerpa racemosa . Te animals were described as leaf green with opaque white spots, with a few dark green spots on the digestive gland. Te illustration of the specimens (Prabhakara Rao 1965: fig. 1) and the host alga are more consistent with those of E. pseudochloris and therefore are here assigned to this species. Subsequently, Ganapati and Sarma (1972) reported recently metamorphosed juvenile specimens also found on C. racemosa in India and assigned them to T. limax . Again, based on the host alga, this record is here considered to be of E. pseudochloris .

We examined several specimens from Japan that are morphologically consistent with the characteristics of T. limax , some of which were collected and identified by S. Kawaguti. Tese specimens have a conical stylet in the penis, which is absent in other specimens of Juliidae here examined. Unfortunately, we were unable to obtain sequence data from those specimens, thus we cannot confirm that they are genetically distinct. However, these Japanese specimens are morphologically distinct from other species here recognized, and therefore we regard T. limax as a valid species, probably endemic to Japan. Finally, because T. limax is morphologically coherent with other recent species here considered to be members of Edentellina , it is here transferred to this genus.