Baeolidia gracilis, 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 : 500-501

Baeolidia gracilis sp. nov.

LSID urn:lsid:zoobank.org:act:A50C22AD-2E31-4D77-841F-7DEF78087E20 ( Figs. 12 B, 13A–B, 14A)

Berghia sp. 2: Gosliner et al. 2008, 404.

Material examined. Holotype: CASIZ 0 83766, one specimen, dissected, 9 mm in length preserved, Philippines, Luzon, Batangas Province, Calumpan Peninsula, Maricaban Strait, collected by Terrence M. Gosliner, 22 February 1992.

Type locality and habitat. Arthur's Rock (South West side of Calumpan Peninsula), Maricaban Strait, Calumpan Peninsula, Batangas Province, Luzon, Philippines. Found under coral rubble in 10 m of water.

Geographical distribution. Thus far, known only from the Philippines (present study).

Etymology. The specific name refers to the slender body of this species.

External morphology ( Figs. 12 B): Body moderately elongate, tapering close to translucent posterior end of foot. Foot corners rounded. Head and pericardium dark greyish blue. Posterior part of notum and cerata ochre. Iridescent greyish blue and bright ochre pigment over pericardium. Reticulate brown pattern close to foot edges. Rhinophores approximately equal in length to oral tentacles. Rhinophores dark greyish blue with only few moderately short papillae, mainly in posterior part. Oral tentacles short, slender, tapering near apices. Oral tentacles with same colour as rhinophores.

Cerata long, flattened, pod-bean-like. Cerata with greenish ochre net, converging on translucent apex. Inner margin with opaque white line. Cerata in three arches followed by five rows, leaving a distinct gap between prepericardial group and post-pericardial groups. Each group with 1–9 cerata, decreasing in size towards foot. Anus cleioproctic, below second right arch. Gonopore among cerata of anteriormost group on right.

Anatomy. Masticatory process smooth ( Fig. 13 A). Radular formula 9 x 0.1.0 (CASIZ 0 83766, 9 mm). Radular teeth bilobed with 48–63 elongate, acutely pointed denticles on either side of notch ( Fig. 13 B). Two pairs of oral glands. Oral glands delicate. First pair elongate, laying dorso-laterally to buccal bulb. Second pair smaller, rounded, emptying on ventral side of head. Salivary glands absent.

Reproductive system diaulic ( Fig. 14 A). Preampullary duct widening into short ampulla. Postampullary duct dividing into oviduct and vas deferens. Vas deferens inserting into wider proximal portion of penial sac, with unarmed penial papilla. Receptaculum seminis moderately large, ovoid, short stalk connecting to short oviduct, before latter forms female glands. Vagina ventral to penis.

Remarks. While most of the Baeolidia species have a stout body, Baeolidia gracilis sp. nov. is much more slender than the others members of this genus (see e.g. Fig. 12 ). The cerata of this species are also particular. They are long, flattened and pod-bean-like rather than being leaf-like. This morphological features and its colour pattern characterize this species. Regarding colouration, B. gracilis sp. nov. most closely resembles B. rieae sp. nov. and B. lunaris sp. nov.. However, B. gracilis sp. nov. has a white line on the inner margin of the cerata that is not present in B. rieae . sp. nov. Moreover, B. rieae sp. nov. lacks the second pair of oral glands of B. gracilis sp. nov.. The latter species does not have the white spot close to the base of cerata of B. lunaris sp. nov.. Both species also differ in the radular morphology (see Fig. 11 E–F for B. lunaris sp. nov. and 13A–B for B. gracilis sp. nov.). In terms of internal anatomy, in addition to this new species, only B. variabilis sp. nov. and B. palythoae have two pairs of oral glands. B. variabilis sp. nov. and B. gracilis sp. nov. have consistent differences in colouration, while B. palythoae has papillae over the masticatory border, which is smooth in B. gracilis sp. nov..

Figures

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.

FIGURE 12. Photographs of the living animals. (A) Baeolidia lunaris sp. nov., specimen from Tanzania, photo by Terrence M. Gosliner, CASIZ 099221; (B) Baeolidia gracilis sp. nov., specimen from the Philippines, photo by Terrence M. Gosliner, CASIZ 083766; (D) Baeolidia scottjohnsoni sp. nov., specimen from Marshall Islands, photo by Scott Johnson, CASIZ 184503.

FIGURE 13. Scanning electron photographs. (A – B) Baeolidia gracilis sp. nov. (CASIZ 083766); (A) Detailed view of the masticatory border; (B) Radular teeth; (C – D) Baeolidia scottjohnsoni sp. nov. (CASIZ 184503); (C) Detailed view of the masticatory border; (D) Radular teeth. Scale bars: A, 3 µm; B, 10 µm; C, 50 µm; D, 100 µm.

FIGURE 14. Reproductive system. (A) Baeolidia gracilis sp. nov., specimen from the Philippines (CASIZ 083766); (B) Baeolidia scottjohnsoni sp. nov., specimen from Marshall Islands (CASIZ 184503). Scale bars: A, 0.5 mm; B, 1 mm. Abbreviations: am, ampulla; fgm, female gland mass; ps, penial sac; rs, receptaculum seminis; v, vagina; vd, vas deferens.