Philine babai, Valdés, 2008

Valdés, Ángel, 2008, Deep-sea “ cephalaspidean ” heterobranchs (Gastropoda) from the tropical southwest Pacific, Mémoires du Muséum national d'Histoire naturelle 196, pp. 587-792 : 721-722

Philine babai n. sp.

Figs 64C-E, 67, 68

TYPE MATERIAL. — Holotype MNHN 20392 and 4 paratypes MNHN 20393-20395, 1 paratype LACM 3000 .

TYPE LOCALITY . — Fiji, 18°16’S, 178°41’W, 478-500 m [ BORDAU 1 : stn CP 1468] .

MATERIAL EXAMINED. — Indonesia. KARUBAR: stn DW 24 , Kai 3 lv, holotype ( MNHN 20392 ) and paratypes ( MNHN 20393 ; Islands 05°32’S, 132°51’E, 230-243 m, 1 dd, paratype ( MNHN Figs 67A-E).

20394). Wallis Island. MUSORSTOM 7: stn DW 610, 13°21’S, 176°09’W, New Caledonia proper. BATHUS 4: stn CP 948, 20°33’S, 286 m, 1 dd, paratype ( MNHN 20395).

164°57’E, 533-610 m, 1 lv, paratype ( LACM 3000). Tonga. BORDAU 2: stn CP 1568, NW of Tongatapu, 21°02’S, Loyalty Ridge. BIOCAL: stn DW 08, 20°34’S, 166°54’E, 435 m, 1 lv. 175°19’W, 431 m, 2 lv, 1 destroyed to dissect the radula and Fiji. BORDAU 1: stn CP 1468, 18°16’S, 178°41’W, 478-500 m, gizzard plates (Figs 64C-E).

DISTRIBUTION. — Known from Indonesia, Fiji, New Caledonia, Tonga and Wallis Island (Fig. 68), in 243-533 m, live in 431-533 m.

DESCRIPTION. — External morphology. The body is oval, 18 mm long (holotype). The cephalic shield is oval, narrower anteriorly and wider posteriorly, comprising about 1/2 of the body length (Fig. 67A). The 2 Hancock’s organs are composed of 19 simple folds. The parapodia are narrow and do not reach the midline of the body. The posterior shield is rounded posteriorly, with no lobes or extensions. The gill is simple, with 18 simple lamellae (Fig. 67B). The colour of the living animals is uniformly white.

Shell morphology. The shell is internal, wide, with a large aperture and a short columellar portion. The shell is very fragile and could not be dissected intact from any of the specimens examined. It occupies most of the dorsal surface of the posterior shield. Sculpture of

FIG. 67. External morphology and anatomy of Philine babai n. sp., paratype MNHN 20393 from Fiji, BORDAU 1 stn CP 1468. A, dorsal view of the preserved animal, scale bar = 1 mm; B, mantle cavity, scale bar = 1 mm; C, anterior portion of the digestive system, scale bar = 1 mm; D, male reproductive system, scale bar = 1 mm; E, detail of the penis, scale bar = 0.5 mm. Abbreviations: ap, anal papillae; bb, buccal bulb; cns, central nervous system; cs, cephalic shield; es, oesophagus; ej, ejaculatory portion of the deferent duct; gl, gill; gz, gizzard; gzp, gizzard plate; pn, penial sac; pr, prostate; ps, posterior shield; rm, retractor muscle; sg, salivary gland.

a number of punctuated spiral grooves. The punctuations are completely fused to the next one within each groove, forming continuous lines (Fig. 64D). The grooves are separated by gaps about as wide as the grooves themselves. Colour uniform whitish to light brown.

Anatomy. The buccal bulb is large and connects posteriorly with the wide oesophagus and the small salivary glands (Fig. 67C). Two strong retractor muscles attach posteriorly to the buccal bulb. The oesophagus opens into a large muscular gizzard, which contains 3 gizzard plates, of which 2 are long and narrow with 2 elongate lateral depressions (Fig. 64E), whereas the third is wider and shorter with no depressions (Fig. 64E). The radular formula is 16 x 1.0.1. The lateral teeth are hook-shaped, with a wide base and a long, curved cusp (Fig. 64C). The cusp of each tooth bears numerous denticles on its inner side.

The reproductive system is monoaulic. The penis is large and complex, with 2 lobes and a retractor muscle attached (Fig. 67E). There is no incurrent sperm duct. The ejaculatory duct has several loops and opens into the penial sac (Fig. 67D). The prostate is very long and convoluted.

REMARKS. — Philine babai is most similar to P. habei n. sp. in external morphology, but they are clearly distinguishable in several regards. The gizzard plates of P. babai are not perforated, whereas they have 2 central holes in P. habei ; the plates of P. babai are smaller than those of P. habei , and one of them is clearly narrower than the other two. The radula of P. babai contains denticulate lateral teeth, whereas the teeth of P. habei are smooth, with no denticles. The reproductive system of P. babai lacks an incurrent sperm duct. Finally, the shell of P. babai has spiral grooves, absent in P. habei .

Anatomically, Philine babai resembles the specimens from Hong Kong provisionally assigned to Philine orientalis A. Adams, 1854 by Rudman (1998b). Philine babai and P. orientalis differ in the shape of the gizzard plates, which are irregular and similar in length in P. babai , but regularly fusiform, with one of them smaller in P. orientalis .

ETYMOLOGY. — Dedicated to the memory of Kikutaro Baba, who pioneered the study of the Japanese opisthobranch fauna.