360 
THE CORAL TRIANGLE: HEARST BIODIVERSITY EXPEDITION 
rather than being acutely tapered as P. acuticauda. In P. acuticauda and P. alboides the inner later¬ 
al teeth entirely lack denticles, while inE! alba, some of the teeth have minute denticles on the mas¬ 
ticatory border, while other teeth in the same radula may entirely lack denticles. In both P. alba and 
P. alboides the two outer lateral teeth are similar in shape with evenly curved cusps. In P. acuticau¬ 
da, the inner of these two teeth is similar to those found in the other two species but the outer one 
has a dramatically reduced cusp. Both P alba and P alboides have three small evenly-sized giz¬ 
zard plates, while no trace of plates was found in the two specimens of P acuticauda examined. 
The prostate of P. acuticauda is only slightly curved as posteriorly directed while in P. alba and 
P. alboides, the prostate is sharply curved, with the posterior end being anteriorly directed. 
Philine hearstorum Gonzales and Gosliner, sp. nov. 
Figures IC-D, 4-5 
Material Examined,— Holotype: dissected, CASIZ 189336, ST HERD 35, beam trawl in 
fine mud, 397-439 m depth, western end of Verde Island Passage, midway between Ambil Island 
and Calatagan, Batangas Province, Luzon, Philippines, 13.809°N, 120.46783°E, 4 June 2011, 
Hearst Expedition Deep Sea Team. 
Geographical Distribution. — Known only from the Philippines (present study). 
Etymology. — The name ''hearstonim'' honors Will and Margaret Hearst who generously 
funded the 2011 Hearst Philippine Biodiversity Expedition. 
Natural History. — This species was found in fine mud. The gizzard contained fragments 
of tissue that when sequenced were found to be mytilid bivavles. 
Description. — External morphology. The living animal (Figs. IC-D) was 25 mm in length 
17 mm wide. The general body color of the living animal is uniformly white with yellowish pig¬ 
ment on the anterior end of the head and in the mantle cavity on the ventral side. The cephalic 
shield is shorter than the posterior shield and is shghtly indented posteriorly. The parapodia are 
short, not reaching the cephalic shield, leaving the anterior and posterior shields visible. The pos¬ 
terior end of the posterior shield tapers to an elongate, rounded posterior terminal. The gill is sim¬ 
ply plicate consisting of 12 primary folds and is situated ventrally on the right posterior end of the 
animal. 
Shell (Fig. 4A): The shell is approximately 15 mm long and is relatively thickly calcified and 
wide. It occupies the majority of the posterior shield. More than 30 radial bands of obvious sculp¬ 
ture are visible on the surface of the shell. The right posterior extreme of the shell has a short exten¬ 
sion. 
Digestive system (Figs. 4B-E, 5A): The buccal mass is relatively large, occupying the anteri¬ 
or half of the anterior shield (Fig. 5 A). The buccal bulb has a relatively large radula. The radular 
formula of the holotype specimen is 16 x 2.1,0.1.2 (Fig. 4D). The inner lateral teeth are large and 
broad (Fig. 4E). Their masticatory margin is devoid of denticles. The two outer lateral teeth are nar¬ 
row and elongate with an elongate, curved cusp. There is a large ventral oral gland and small dor¬ 
sal oral glands. At the posterior end of the buccal mass, near the junction with the crop, is a pair of 
elongate salivary glands. The crop is large and saccate, about the same diameter as the buccal bulb. 
Posteriorly the crop narrows to a slightly muscularized gizzard that contains three symmetrical 
plates (Figs. 4B-C). The gizzard plates are brown and covered with small rhomboidal crystals. The 
gizzard narrows posteriorly and enters the digestive gland. The intestine emerges from the right 
side of the digestive gland and terminates near the posterior end of the body near the base of the 
gill. 
Central Nervous System (Fig. 5A): The circumesophageal nerve ring consists of paired cere- 
