Baeolidia japonica Baba, 1933

Carmona, Leila, Pola, Marta, Gosliner, Terrence M. & Cervera, Juan Lucas, 2014, Review of Baeolidia, the largest genus of Aeolidiidae (Mollusca: Nudibranchia), with the description of five new species, Zootaxa 3802 (4), pp. 477-514 : 486-487

Baeolidia japonica Baba, 1933

( Figs. 2 D–E, 3C, 4E–F, 6C).

Baeolidia japonica Baba, 1933: 282 , Fig. 8 .

Spurilla japonica (Baba, 1933) : Rudman 1982, 193. Berghia japonica (Baba, 1933) : Gosliner 1985, 261.

Type locality. Tomioka Bay, Japan.

Type material. To our knowledge no type material remains. We designate the specimen CASIZ 1814520 from Ose, Japan, as the neotype in order to avoid confusion with similar species.

Material examined. Neotype: CASIZ 1814520, one specimen, dissected, 2 mm in length preserved, immature, Japan, Ose, collected by Akira Kawahara, 10 February 2010. Other material: CASIZ 186795, one specimen, dissected, 8 mm in length preserved, Marshall Is., collected by Scott Johnson, 12 September 2011; CASIZ 181357, one specimen, dissected, 5 mm in length preserved, Marshall Is., collected by Scott Johnson, 27 December 2008.

Geographical distribution. Originally described from Tomioka Bay, Japan (Baba 1933) it is also known from Shimoda ( Nakano 2004), the Ryukyu Is. ( Ono 2004), Indonesia (Gosliner et al. 2008), the Marshall Is. (present study), Philippines (Gosliner et al. 2008), and Papua New Guinea (Gosliner et al. 2008).

External morphology ( Figs. 2 D–E, 3C): Body short, broad, tapering close to posterior end of foot. Foot corners tentaculiform. Body colour brown or translucent white. Bright white spots over dorsum, forming continuous patch from pericardial area to posterior end of foot. Tiny white spots form white mark over head. Rhinophores, oral tentacles and foot corners translucent white. Rhinophores shorter than oral tentacles. Rhinophores full of elongate, white papillae ( Fig. 3 C); apex white. Oral tentacles with white spots. Cerata moderately short, flattened, almost leaf-like. Cerata usually brownish with white spots, or translucent covered by white pigment; density of white spots varies; some specimens with bluish band on anterior side; a minute white ring on apex. Cerata in two arches followed by rows, leaving a distinct gap between pre and post-pericardial groups. Each group with 4–11 cerata, decreasing in size towards foot. Anus cleioproctic, within right second arch. Gonopore among cerata of anteriormost arch on right.

Anatomy. Masticatory borders smooth ( Fig. 4 E). Radular formula 33 x 0.1.0 ( CASIZ 181357, 5 mm). Radular teeth slightly bilobed with 27–36 elongate, acutely pointed denticles on either side of the inconspicuous central notch ( Fig. 4 F). Teeth progressively smaller in posterior region of radula. Oral glands small, fragile, spongy. Oral glands dorso-laterally to buccal bulb. Salivary glands long.

Reproductive system diaulic ( Fig. 6 C). Preampullary duct widening into moderately short ampulla. Postampullary duct dividing into oviduct and vas deferens. Vas deferens entering into wider proximal portion of penial sac with unarmed penial papilla. Receptaculum seminis huge, rounded, short stalk connecting to long oviduct, before latter forms female glands. Vagina ventral to penis.

Remarks. When Baba (1933a) described Baeolidia japonica , he did not mention anything about colouration. It was sixteen years later ( Baba 1949) when the first colour figure of B. japonica was published. In that contribution, Baba depicted this species as “ground-colour dark brown, the whole back sprinkled with opaque white spots”. This description clearly does not match with our specimens, which are mainly white. Nevertheless, in the same area where Baba described B. japonica , both colour types (brownish and whitish) cohabit ( Rudman 2002; Nakano 2004; Ono 2004). Since one of our specimens is from the type locality of B. japonica , we conclude that both colour types are conspecific.

Excluding Baeolidia scottjohnsoni sp. nov., the main internal differences between B. japonica and the remaining species of the genus is the shape and the size of the receptaculum seminis. This structure is bigger and more rounded in B. japonica than in the remaining Baeolidia species. Due to this particular receptaculum seminis, it cannot be confounded with the remaining species of the genus. Its distinction from B. scottjohnsoni sp. nov. will be discussed in the remarks section for that species.

Carmona et al. (2013) studied this species from a molecular approach ( Fig. 1 ).

Figures

FIGURE 1. Phylogeny of Baeolidia, based on Carmona et al. (2013). Names on right side of vertical bars refer to revised classification.

FIGURE 2. Photographs of the living animals. A, B, Baeolidia moebii: (A) specimen from the Philippines, photo by Terrence M. Gosliner, CASIZ 177602; (B) specimen from Mozambique, photo by Yara Tibiriça, MNCN 15.05 / 63447; (C) Baeolidia macleayi, specimen from Australia, photo by Terrence M. Gosliner, CASIZ 71923; (D-E) Baeolidia japonica: (D) specimen from Japan, photo by Akira Kawahara, CASIZ 1814520; (E) specimen from Marshall Islands, photo by Scott Johnson, CASIZ 186795; (F) Baeolidia ransoni, specimen from the Philippines, photo by Terrence M. Gosliner, CASIZ 186208.

FIGURE 3. Different papillate rhinophores in Baeolidia: (A) from Rudman (1982); (B) from Gosliner (1985). Scale bars: A, 3 mm; B, 1 mm; C, 1.2 mm; D, 1.5 mm.

FIGURE 4. Scanning electron photographs. (A – B) Baeolidia moebii (CASIZ 180327): (A) Detailed view of the masticatory border; (B) Radular teeth; (C – D) Baeolidia macleayi (CASIZ 195247): (C) Detailed view of the masticatory border; (D) Radular teeth; (E – F) Baeolidia japonica (CASIZ 181357); (E) Detailed view of the masticatory border; (F) Radular teeth. Scale bars: A, 10 µm; B, 30 µm; C-D, 10 µm; E, 100 µm; F, 150 µm.

FIGURE 6. Reproductive system. (A) Baeolidia moebii, specimen from Mozambique (MNCN 15.05 / 63447); (B) Baeolidia macleayi, specimen from Australia (CASIZ 195247); (C) Baeolidia japonica, specimen from Marshall Islands (CASIZ 181357); (D) Baeolidia ransoni, specimen from the Philippines (CASIZ 186209). Scale bars: A – D, 0.5 mm. Abbreviations: am, ampulla; fgm, female gland mass; ps, penial sac; rs, receptaculum seminis; va, vagina; vd, vas deferens.

FIGURE 8. Photographs of the living animals. (A) Baeolidia harrietae, specimen from Papua New Guinea, photo by Terrence M. Gosliner; (B) Baeolidia australis, specimen from Australia, photo by Lean and David Atkinson; (C) Baeolidia salaamica, specimen from the Philippines, photo by Terrence M. Gosliner, CASIZ 177599; (D) Baeolidia salaamica, specimen from the Philippines, photo by Terrence M. Gosliner, CASIZ 177397; (E) Baeolidia chaka, specimen from South Africa (6 mm), photo by Terrence M. Gosliner; (F) Baeolidia palythoae, specimen from South Africa (8 mm), photo by Terrence M. Gosliner.