Ascidicola philippinensis Kim & Boxshall 2021, sp. nov.

Ascidicola philippinensis sp. nov.

(Figs. 4, 5)

Type material. Holotype ♀ (MNHN-IU-2018-1941, dissected and mounted on a slide) from mterygascẚdẚa lçnga (Van Name, 1918); The Philippines, MUSORSTOM 3 cruise, RV “Coriolis”, Stn CP 131 (11°27´N, 121°43´E), depth 120-122 m, Bouchet & Triclot-MNHN coll., 05 June 1985.

Etymology. The name of this new species is based on the type locality.

Description of female. Body (Fig. 4A) elongate, body shape and segmentation as in type species, A. rçsea. Body length 3.40 mm. Prosome (Fig. 4B) slightly depressed dorsoventrally, about 1.0 mm long, occupying 29% of body length. Cephalosome 369×438 μm, with rounded anterior margin; first to fourth pedigerous somites 92×400, 138×446, 154×488, and 230×378 μm, respectively. Urosome 5-segmented, curved dorsally; genital somite about 860 μm long (average of longer ventral and shorter dorsal margins); copulatory pore positioned on ventral surface at anterior 17% of somite length. First and second abdominal somites 470 and 446 μm long, respectively; anal somite (Fig. 4C) slightly tapering, about 1.5 times longer than wide (477×315 μm), widest anterior 20% of somite length; anal operculum broad. Spinose pad lacking between second abdominal and anal somites. Caudal ramus (Fig. 4D) tapering, 2.76 times longer than wide (149×54 μm), 31% as long as anal somite, armed with 6 small setae and or- namented with several rows of minute spinules; all caudal setae shorter than proximal width of ramus; lateral and subdistal dorsal setae positioned at 42% and 70% of ramus length, respectively.

Rostrum absent. Antennule (Fig. 4F) short, 138 μm long, 5-segmented; all segments wider than long; armature formula 5, 8, 4, 4, and 12; setae naked and of different lengths, some of shorter, blunt setae aesthetasc-like. Antenna (Fig. 4G) 3-segmented, consisting of coxobasis and 2-segmented endopod; coxobasis slightly longer than wide (54×46 μm), bearing 1 strong spine (50 μm long) distally; first endopodal segment 35×25 μm, bearing 1 strong spine (46 μm long) subdistally; second endopodal segment gradually narrowing distally, 1.90 times long than wide (78×20 μm), terminating in slender claw (28 μm long); armed with 1 small spine proximally and 4 setae distally (one 73 μm long, much longer than other 3).

Labrum (Fig. 5A) broad, with 2 dentiform processes at each posterolateral corner and row of minute spinules along posterior margin. Mandible (Fig. 5B) consisting of coxa and palp: coxal gnathobase broadened, medial margin bearing strong tooth distally, 3 larger and 3 smaller teeth; larger teeth bearing 1 or 2 subsidiary denticles; palp 1-segmented, articulated with broad, pedestal-like extension of coxa, armed with 5 unequal setae, largest seta (on medial margin) 110 μm long. Maxillule (Fig. 5C) consisting of precoxa and palp; precoxa with medially extended arthrite bearing 7 spines and 1 small proximal seta; palp distinctly articulated from precoxa, bearing 8 elements (5 unequal spines and 3 setae). Maxilla (Fig. 5D) consisting of syncoxa and allbasis; syncoxa broad, bearing 1 endite tipped with 2 setae (proximal seta larger and spiniform); allobasis terminating in claw-like process, bearing 6 setae on outer margin and 1 small seta on inner margin. Maxilliped (Fig. 5E) slender, digitiform, bearing 1 apical and 2 medial setae; ornamented with fine spinules distally.

Legs 1-4 (Fig. 5 F-I) biramous with 2-segmented rami; coxa unarmed; intercoxal sclerite narrow; setae on endopods large and stiff, as usual for genus. Leg 1 with inner distal seta on basis 28 μm long, longer than first endopodal segment. Medial of 2 distal spines on second exopodal segment of legs 1-4 denticle-like, much smaller than outer spine but distinctly articulated at base. First endopodal segment unarmed in legs 1 and 2, but with inner seta in legs 3 and 4. Armature formula for legs 1-4 as follows:

[table omitted]

Leg 5 (Fig. 4E) lamellate, encircling fifth pedigerous and genital somites, extending to posterior margin of genital somite, bearing 3 minute setules (2 ventro-proximal and 1 ventro-distal); left and right legs separated from each other on dorsal side, but fused proximally on ventral side. Leg 6 not examined.

Male. Unknown.

Remarks. Ascẚdẚcçla phẚlẚppẚnensẚs sp. nov. differs from A. rçsea, A. secunda, and A. antarctẚca sp. nov. described below in having 2 spines + 1 seta on the second endopodal segment of leg 1 (in contrast to 3 spines + 1 seta in all three congeneric species) and 3 spines + 3 setae on the second endopodal segment of leg 3 (in contrast to 2 spines + 3 setae in A. secunda and 4 spines + 3 setae in the other two congeners). The numbers of spines on the second exopodal segments of legs 1-4 of the new species are same as in A. secunda, but the shape and arrangement of the spines are quite different between the two species: there are fewer spines on the outer margin of the segment in A. phẚlẚppẚnensẚs sp. nov. and it lacks the small, dentiform inner distal spine that is present on this segment in A. secunda. The possession of 3 setae on the maxilliped is an additional difference between A. phẚllẚppẚnensẚs sp. nov. and both A. rçsea and A. secunda which have 5 and 4 setae, respectively, on the maxilliped.