Philinopsis aliciae Gosliner, 2015

Gosliner, Terrence, 2015, Three New Species of Aglajid Cephalaspidean Mollusks from the Tropical Indo-Pacific of the Verde Island Passage, Proceedings of the California Academy of Sciences 62 (6), pp. 191-205 : 197-199

Philinopsis aliciae Gosliner , sp. nov.

Figures 1A–B , 2B , 5.

MATERIAL EXAMINED.— HOLOTYPE: PNM 41061 , dissected, 5 m depth, subsampled for molecular study, Anilao Harbor , Mabini, Batangas Province, Luzon, Philippines, 13.75994°S, 120.83036°E, 30 April 2011, A. Hermosillo.

GEOGRAPHICAL DISTRIBUTION.— Known only from the southern Luzon Island, Philippines (present study).

ETYMOLOGY.— The name “aliciae ” honors my good friend and colleague, Alicia Hermosillo, who collected this specimen. Ali’s keen eye and infectious enthusiasm brighten up any field trip and produce a wealth of remarkable new observations and species.

NATURAL HISTORY.— This species is found in the same habitat and at the same locality as the preceding species on a sandy bottom in 5 m depth. Little else is known about its biology.

DESCRIPTION.— External morphology: The living specimen was 11 mm in length and 4 mm wide. The general body color of the living animal ( Figs. 1A–B ) is mottled dark chocolate brown. Between the brown regions are clear areas of transparent white, which contain minute flecks of light green. The living animal is elongate and wide. The anterior end of the cephalic shield is uniformly round but blunt and quadrangular. The cephalic shield is roughly rectangular and terminates posteriorly with a medial, rounded knob. The posterior shield is slightly rounded anteriorly and terminates in a rounded lobe without any extension. The two lateral posterior lobes of the posterior shield are short and simply rounded. They are about equal in length. The parapodia are very short, leaving most of the cephalic and posterior shields visible. The gill is simply plicate consisting of 13 primary folds and is situated on the right posterior side of the animal.

Shell ( Figs. 2B , 5A): The shell is relatively thickly calcified and consists of a thicker band that occupies the posterior extreme of the animal. There is a thin membranous periostracum that is slightly more extensive anteriorly than the calcified portion. The area at the base of the shell near the protoconch is more thickly calcified that the rest of the shell and a posterior lobe is present on the left side of the shell. The shell was fractured into several pieces prior to dissection.

Digestive system: The buccal mass is large, highly muscularized and slightly elongate posterital atrium where it joins the duct of the bursa copulatrix. The bursa is large and spherical. Its duct is narrow where it joins the bursa and widens until its widest portion at the muscularized genital atrium. From the genital atrium, the open, ciliated sperm groove leads to the cephalic penis. The penis (Fig. 5C) consists of a penial sac and a lobate prostate gland that is joined to the penial sac by a narrow duct. Within the penial sac is a large, curved penial papilla, which appears to be devoid of spines.

REMARKS.— Philinopsis aliciae is very similar in its external coloration to some specimens of P. buntot , described above. Most significantly, it lacks the distinct “tail-like” posterior appendage of the posterior shield, which characterizes P. buntot . Internally, there are also significant differences, as well. The central nervous system of P. buntot contains a distinct genital ganglion (Fig. 3A) at the posterior end of the central nervous system, which is absent in P. aliciae . The general shape of the penis is similar in the two species, with a well-developed prostate separated form the penis by a thin duct. In P. buntot , the prostate is oblong in shape, whereas in P. aliciae it is more irregular in shape. The penis of P. buntot has a series of undivided and bifurcate spines on the the penial collar and two lobes of the penial papilla. In P. aliciae , the penis contains a single simple lobe, lacks a penial collar and lacks any armature on the penial papilla. Both P. buntot and P. aliciae are sympatric and were collected from the same dive site on the same dive. The two species avoid- ed eachother when placed in the same container. When multiple specimens of P. buntot were observed together they aggregated and were observed mating with each other. Both species have marked genetic differences and P. aliciae does not cluster with other species of Philinopsis (unpublished data), likely owing to the lack of amplification of the 16S and H3 genes for this species. This species is tentatively described as a species of Philinopsis , based on anatomical characters, but verification of its systematic position must await additional molecular study.

Figures

FIGURE 1. Living animals A–B. Philinopsis aliciae sp. nov., holotype, PNM 41061, Mabini, Philippines. C. Philinopsis buntot sp. nov., holotype, PNM 41060, Mabini, Philippines, ventral view showing markings on foot. D. Philinopsis buntotparatype, CASIZ 185942, Tingloy, Philippines. E. Chelidonura alexisi sp. nov., holotype, PNM 41062, Mabini, Philippines.

FIGURE 2. Shells.A. Philinopsis buntot. sp. nov., paratype, CASIZ 185942, Tingloy, Philippines. B. Philinopsis aliciae sp. nov., holotype, PNM 41061, Mabini, Philippines. C. Chelidonura alexisi sp. nov., holotype, PNM 41062, Mabini, Philippines.