Periproctia spissa sp. nov.
(Figs. 135, 136)
Typematerial. Holotype (intact ♀, MNHN-IU-2014- 21263) and paratype ♀ (dissected and figured) from Pseudodistoma aureum (Brewin, 1957) (MNHN-IT-2008-7326 = MNHNA1/PSE/67), CRRFOCDN 8852-H, Baluan, Papua New Guinea (02°32.27 Ś, 147°17.97 É), depth 7 m, 22 June 2003 .
Additional material. 1 ♀ (dissected) from Pseudodistoma sp., Papua New Guinea (02°40.68 Ś, 150°28.23 É), depth 18 m, 03 July 2003, coll. CRRF, OCDN 9100-2.
Etymology. The specific name is derived from the Latin spiss (=compact), alluding to the stout body form of the new species.
Description of female. Body (Fig. 135A, B) consistingof stout prosome and small urosome. Body length 850 μm. Prosome cylindrical, slightly depressed, 646 μm long, consisting of cephalosome and 4 pedigerous somites; somites only recognizable by retained dorsal tergites separated by constricted, wrinkled regions. Cephalosome roughly pentagonal in dorsal view. Greatest width of prosome 317 μm at level corresponding to second pedigerous somite. Second to fourth pedigerous somites forming brood pouch; fifth pedigerous somite completely fused with fourth. Free urosome (Fig. 135C) 5-segmented: genitalsomite 63×122 μm; genital apertures distinct, located dorsally. Four abdominal somites 51×85, 51×76, 74×63, and 51×51 μm, respectively. Firsttothird abdominal somites ornamented with transverse rows of small spinules on ventral surface. Third abdominal somite distinctly longerthan wide. Anal somite (Fig. 135D) highly sclerotized, subrectangular, with concave posterior margin in ventral view; ornamented with spinules near posterolateral corners. Caudalramus (Fig. 135E) small, 1.2 timeslongerthan wide (30×25 μm), narrowing distally; armed with 3 claws (2 strong distal and 1 slender ventral) and 3 setae (2 pinnate and 1 naked); lengths of claws 44, 31, and 20 μm.
Rostrum (Fig. 135F) slightly widerthan long, 55×57 μm, tapering steeply towards beak-like apical process; ornamented with 3 pairs (proximal, middle, and distal) of small setules (or sensillae). Antennule (Fig. 135G) 110 μm long and 8-segmented; armature formula 2, 12 (or 5, 9), 8+aesthetasc, 3, 2+aesthetasc, 2, 2+aesthetasc, and 7+aesthetasc; some of larger setae pinnate (2 on first, 4 on second, and 2 on third segments); fourth segment with trace of subdivisionon posterior side.Antenna (Fig. 135H) 4-segmented; coxa short and unarmed; basis slightly longerthan wide, bearing large, pinnate seta representing exopod at outer distal corner; first endopodal segment also slightly longer than wide, with 1 naked seta on inner margin; compound distal segment about 2.9 times longer than wide (52×18 μm), ornamented with spinules on inner margin; armedwith 8 setae (including 1 pinnate and 4 blunt setae) plus small terminal claw, less than half length of segment.
Labrum with setulose posterior margin and shallow posteromedianlobe. Mandible (Fig. 136A) with 4 teeth, 1 spinule between distal second and third teeth, and 1 small seta on coxal gnathobase; basis with 1 seta on subdistal medial margin; exopod 2-segmentedwith 3 setaeonfirst segment and 2 setae on small second segment; setae on secondsegment shorter than setae on first; endopod 2- segmentedwith 2 and 6 setae onfirst and second segments, respectively. Maxillule (Fig. 135I) with 9 setaeon arthrite, 1 on coxal endite, 2 on epipodite, 3 on basis, 3 on exopod and 4 on endopod. Maxilla (Fig. 136B) 5-segmented; syncoxawith 9 setae (arranged as 3, 1, 2, and 3), 2 on basis, and 1, 1, and 2 on first to third endopodal segments, respectively. Maxilliped (Fig. 136C) unsegmented, armed with 9 setae (8 medial and 1 apical).
Legs 1–4 (Fig. 136 D–G) each with 3-segmented exopod and 2-segmented endopod. Inner coxal seta absent in all legs. Outer seta of basis large in leg 1, small in legs 2–4. Innerdistalspineonbasisofleg 1 slightlylonger than first endopodal segment. Outer and distal setae on exopods of legs 2–4 rod-shaped, with blunt tip. Armature formula for legs 1–4 as follows:
| Coxa | Basis | Exopod | Endopod | |
|---|---|---|---|---|
| Leg 1 | 0-0 | 1-I | I-1; I-1; II, I, 4 | 0-0; 1, 2, 3 |
| Leg 2 | 0-0 | 1-0 | 1-1; 1-1; 3, 1, 5 | 0-1; 1, 2, 5 |
| Leg 3 | 0-0 | 1-0 | 1-1; 1-1; 2, 1, 5 | 0-1; 1, 2, 5 |
| Leg 4 | 0-0 | 1-0 | 1-1; 1-1; 2, 1, 5 | 0-1; 1, 2, 4 |
Leg 5 (Fig. 136H) represented by small, broad plate bearing 2 small lobes distally; each lobe tipped with 1 naked seta; seta on inner lobe (exopod) shorter than that on outer lobe.
Male. Unknown.
Remarks. The numbers of setae on the maxilliped in all seven known species of Periproctia are as follows: 7 (6 medial and 1 apical) in P. biuncata, 8 (7 medial and 1 apical) in P. triuncata, and 10 (8 medial and 2 apical) in the other species (Table 3). The possession of 9 setae (8 medial and 1 apical) on the maxilliped differentiates P. spissa sp. nov. from all congeneric species. The second endopodal segment of the mandibular palp is armed with 6 setaein P. spissa sp. nov. It shares this setation with P. stocki sp. nov. but all other species described above have only 5 setae. It differs from P. stocki sp. nov. in caudal armature: having 3 claws plus 3 setae compared to 4 claws and 2 setae in P. stocki sp. nov.