Periproctia spinata sp. nov.

(Figs. 145, 146)

Typematerial. Holotype (intact ♀, MNHN-IU-2014- 21269), paratypes (8 intact ♀♀, MNHN-IU-2014- 21670), dissected paratypes (2 ♀♀, figured), from Polysyncraton sp., CRRF OCDN 8467-N, reef, west side of Cebtal Normanby Is., Papua New Guinea (10°00.21 Ś, 150°50.04 É), 18 January 2002 .

Etymology. The specific name is derived from the Latin spina (=thorn) and refers to the spiniform posterolateral cephalosomal processes.

Descriptionoffemale. Body (Fig. 145A) small, inflated, with soft thin exoskeleton. Body length 0.59 mm. Prosome 0.49 mm long. Cephalosome with acutely pointed process at each posterolateral corner. Four pedigerous somites fused, discernible only by faint dorsal wrinkles. Fifth pedigerous somite completely fused with fourth. Free urosome 5-segmented: all urosomites much wider than long. First and second abdominal somites ornamented with small spinules scattered on ventral surface (Fig. 145B). Anal somite slightly protruded posteroventrally, surface of protrusion covered with numerous minute granules. Caudal ramus (Fig. 145B) small, about 1.5 timeslongerthan wide (16×11 μm); armed with 3 subequal claws and 3 naked setae.

Rostrum (Fig. 145C) muchwiderthanlong, rounded distally, lacking apical process. Antennule (Fig. 145D) 134 μm long and 8-segmented; articulations between 3 terminal segments indistinct; armature formula 6, 10, 6+aesthetasc, 3, 2+aesthetasc, 2, 2+aesthetasc, and 7+aesthetasc; all setae naked; proximal 2 setae on first segment not enlarged. Antenna (Fig. 145E) 4-segmented; coxa short and unarmed; basis with large outer exopodal seta; first endopodal segment about 1.3 times longer than wide, with 1 setaon inner marginand minute spinules scattered over surface; compound distal endopodal segment about 3.3 times longer than wide (43×13 μm), ornamented with 4 groups of spinules along outer margin; armedwith 9 setae (3 distalsetae blunt tipped) plus small terminal claw, about half as long as segment.

Labrum(Fig. 145F)taperingstronglytowardsnarrow, setulose apex. Mandible (Fig. 145G) with 3 teethand 1 needle-like spinule between proximal 2 teeth, lacking setaon proximal margin; basis with 1 setaon medial margin; exopod obscurely segmented, armed with 5 setae, outer distal seta slightly shorter than others; endopod incompletely 2-segmented with 2 and 5 setae on first and second segments, respectively. Maxillule (Fig. 145H) with 8 setaeon arthrite, 1 on coxal endite, 2 on epipodite, 3 on medial margin of basis, 3 on exopod, and 4 on endopod. Maxilla (Fig. 145I) 5-segmented; syncoxawith 9 setae (3, 1, 2, and 3); basiswith 2 setae, endopodwith 1, 1, and 3 setae on first to third segments, respectively. Maxilliped (Fig. 146A) with 8 medial setae and 1 apical seta.

Legs 1–4 (Fig. 146 B-E) with 3-segmented exopods and 2-segmented endopods. Inner coxal seta absent in legs 1–4. Outer setaon basis of leg 1 large. Inner distal spine on basis of leg 1 much longer than first endopodal segment, extending to middle of second segment. Outer setae on first and second exopodal segments and all setae on third exopodal segment of legs 2 and 3 naked. Leg 1 lacking inner seta on second exopodal segment. Leg 4 lacking inner seta on first exopodal and first endopodal segments. All setaeon leg 4 naked. Armature formula for legs 1–4 as follows:

Leg 5 (Fig. 146F) small, bilobed; each lobe tipped withnaked seta.

Male. Unknown.

Remarks. Two rare character states of Periproctia spinata sp. nov. are useful in distinguishing this new species from its congeners. Firstly, the second exopodal segment of leg 1 lacks an inner seta. Secondly, the second endopodal segment of leg 4 is armed with only 5 setae. The first character state is shared only with P. biuncata and P. falsiarcuata, but the second character state has not yet been recorded within the genus. Additional diagnostic character states include: the maxilliped bears 9 setae (8 medial and 1 apical) and the first exopodal segment of leg 4 lacks an inner seta. The combination of these four character states allows the new species to be differentiated unequivocally from all of its congeners (Table 3).