Philinopsis ctenophoraphaga Gosliner, 2011

Location: Black Sandy Beach, Amed, Pulau Bali, Indonesia
Date: 2022/08/14
Length: 20mm
Depth: 20.0m
Water temperature: 28.0℃

Description

A head-shield slug 18–40 mm long and 6–15 mm wide. The general body colour is light pinkish to maroon red, with darker red pigment on the anterior portion of the head, along the parapodial margins, and along the elongate appendage on the posterior end of the cephalic shield. The entire dorsal and lateral surfaces are ornamented with scattered opaque white spots, each surrounded by a faint halo of lighter pigment.

The anterior end of the cephalic shield is slightly trilobate, and terminates posteriorly in an elongate triangular appendage that is held upright when the animal is actively crawling. The posterior shield is slightly rounded anteriorly and ends in a bilobed pair of relatively short posterior extensions, forming a skirt around the edge of the mantle. The parapodia are relatively short, leaving most of the cephalic and posterior shields visible. The gill is simply plicate with 10 primary folds and is situated on the right posterior side. The penis is simple and devoid of any armature. The buccal mass is large and bulbous but only weakly muscularized, lacking the thick muscle layer found in most aglajids — apparently an adaptation for feeding on soft, benthic ctenophores rather than more solid molluscan prey.

Distribution

Tropical Indo-Pacific. Recorded from the Philippines, Indonesia and the Red Sea. Type locality: old site of Seafari Resort (Basura), Anilao, Mabini, Batangas Province, Luzon, Philippines (3 m).

Etymology

From the Greek Ctenophora ("comb-bearer", phylum Ctenophora) and phago ("to eat"), referring to the species' observed feeding on benthic ctenophores.

Remarks

The only species of Philinopsis with a pink to maroon coloration and opaque white spots. Also unique in having a more elongate, acutely pointed triangular posterior end of the cephalic shield and a weakly muscularized buccal mass — apparently a specialization for feeding on benthic platyctene ctenophores such as Coeloplana meteoris. Originally described in Gosliner T. 2011 Zootaxa 2751: 1-24.