Baeolidia variabilis, Carmona, Leila, Pola, Marta, Gosliner, Terrence M. & Cervera, Juan Lucas, 2014

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 : 497-498

Baeolidia variabilis sp. nov.

LSID urn:lsid:zoobank.org:act:B6B01F57-6AD8-49AD-B95D-B7F7EE91C9DC ( Figs. 3 C, 9C, 10B–C, 11C–D)

Berghia sp. 1: Gosliner et al. 2008, 404. Berghia sp. 4: Gosliner et al. 2008, 405. Baeolidia sp. A: Carmona et al. 2013, 6.

Material examined. Holotype: CASIZ 103739, one specimen, dissected, 4 mm in length preserved, Philippines, Mindoro, Medio Island, collected by Terrence M. Gosliner, 28 February 1995; Paratype: CASIZ 190618, one specimen, dissected, 3 mm in length preserved, Papua New Guinea, North coast collected by Terrence M. Gosliner, 29 January 1988. Other material: CASIZ 177715, one specimen, dissected, 4 mm in length preserved, Philippines, Luzon, Batangas Province, Calumpan Peninsula, collected by Terrence M. Gosliner, 21 April 2008; CASIZ 177716, one specimen, dissected, 3 mm in length preserved, Philippines, Luzon, Batangas Province, Calumpan Peninsula, collected by Terrence M. Gosliner, 21 April 2008; CASIZ 186210, one specimen, dissected, 2 mm in length preserved, Philippines, Luzon, Batangas Province, Maricaban Island, collected by Terrence M. Gosliner, 21 May 2011; CASIZ 187741, two specimens, dissected, 11 and 10 mm in length alive, Marshall Island, Kwajalein Atoll, collected by Scott Johnson, 24 July 2011.

Type locality and habitat. Medio Island, Mindoro, Philippines. Found in shallow water reefs under coral rubble, where it likely feeds on small sea anemones.

Geographical distribution. So far, only known from the Philippines, the Marshall Islands and Papua New Guinea (present study).

Etymology. In Latin the word “ variabilis ” means variable. The specific name refers to the two colour types of this species.

External morphology ( Figs. 3 C, 10B–C): Body short, broad, tapering close to posterior end of foot. Foot corners, short and rounded. Body colour translucent with two different colour patterns. First one with opaque white patches on head (its density varies) and notum ( Fig. 10 B). Light ochre reticulate on both sides of body. Second one with small light ochre spots all over body ( Fig. 10 C). Rhinophores approximately equal in length to oral tentacles. Rhinophores densely covered by elongate papillae ( Fig. 3 C). Rhinophores translucent with ochre pigment and white apex. Oral tentacles short, slender, tapering near apices. Oral tentacles same colour as ground colour and white tips.

Cerata flattened, almost leaf-like. In first colour pattern, cerata ochre with white pigmentation on posterior side of basal portion. Some cerata noticeably longer than others. In second colour pattern, cerata recurved inwardly, with some papillae or bulbs. Cerata completely white, usually having bright yellow pigment on posterior side of their distal area. Cerata in two or three arches followed by a couple of rows. Cerata groups leaving a distinct gap between pre and post-pericardial groups. Each group with 1–5 cerata, decreasing in size towards foot. Anus cleioproctic, below second right arch. Genital aperture among cerata of anteriormost group on right.

Anatomy. Masticatory process smooth ( Fig. 11 C). Radular formulae 8 x 0.1.0 (CASIZ 103739, 4 mm), 14 x 0.1.0 (CASIZ 177715, 4mm). Radular teeth bilobed with 47–52 elongate and acutely pointed denticles on either side of minute central cusp ( Fig. 11 D). Teeth progressively smaller towards posterior region of radula. Oral glands small, moderately elongate, fragile, spongy, laying dorso-laterally to buccal bulb. Ventral gland present. Salivary glands absent.

Reproductive system diaulic ( Fig. 9 C). Preampullary duct widening into conspicuous ampulla. Postampullary duct dividing into oviduct and vas deferens. Vas deferens short, entering into wider proximal portion of penial sac with unarmed penial papilla. Receptaculum seminis bean-shaped receptaculum seminis, short stalk connecting to long oviduct, before latter forms female glands. Vagina ventral to penis.

Remarks. This particular species highlights how variable the colouration can be within the same species. Gosliner et al. (2008) identified both colour patterns as separate species but the molecular analyses undertaken by Carmona et al. (2013) showed that they are conspecific. Further studies would help to elucidate if these colour patterns depend on habitat, prey and/or an ontogenetic process.

Both colour patterns differ consistently from the remaining Baeolidia species but B. japonica , B. salaamica , B. gracilis sp. nov. and B. scottjohnsoni sp. nov. (see below) are somewhat similar in external appearance. However, B. salaamica is completely translucent, including the cerata, while the body colour of B. variabilis sp. nov. is opaque white or covered by small ochre flecks. B. scottjohnsoni sp. nov. and B. japonica have a characteristic blue band at the anterior side of the cerata, which is not found in B. variabilis sp. nov.. Internally, differences in the size of the receptaculum seminis between B. variabilis sp. nov. and B. scottjohsoni sp. nov. are also obvious ( Fig. 8 C and 14B respectively). None of these species has a ventral oral gland except B. gracilis sp. nov. (see below) but B. variabilis sp. nov. lacks any traces of the iridescent pigment found on B. gracilis sp. nov..

Carmona et al. (2013) included this new species in their molecular phylogeny ( 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 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 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.

FIGURE 9. Reproductive system. (A) Baeolidia salaamica, specimen from Japan (CASIZ 184525); (B) Baeolidia rieae sp. nov., specimen from Japan (CASIZ 184525); (C) Baeolidia variabilis sp. nov., specimen from the Philippines (CASIZ 177715); (D) Baeolidia lunaris sp. nov., specimen from Tanzania (CASIZ 099221). 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 10. Photographs of the living animals. (A) Baeolidia rieae sp. nov., specimen from Japan, photo by Jum Imamoto, CASIZ 184525; (B – C) Baeolidia variabilis sp. nov.: (B) specimen from Marshall Islands, photo by Scott Johnson, CASIZ 187741; (C) specimen from the Philippines, photo by Terrence M. Gosliner, CASIZ 177715.

FIGURE 11. Scanning electron photographs. A, B, Baeolidia rieae sp. nov. (CASIZ 184525); (A) Detailed view of the jaw; (B) Radular teeth; (C – D) Baeolidia variabilis sp. nov. (CASIZ 177715); (C) Detailed view of the masticatory border; (D) Radular teeth; (E-F) Baeolidia lunaris sp. nov. (CASIZ 099221); (E) Detailed view of the masticatory border; (F) Radular teeth. Scale bars: A, 30 µm; B, 100 µm; C, 2 µm; D, 10 µm; E, 10 µm; F, 20 µm.