Periproctia acutirostris, Kim & Boxshall, 2020

Kim, Il-Hoi & Boxshall, Geoff A., 2020, Untold diversity: the astonishing species richness of the Notodelphyidae (Copepoda: Cyclopoida), a family of symbiotic copepods associated with ascidians (Tunicata), Megataxa 4 (1), pp. 1-6 : 197-200

Periproctia acutirostris sp. nov.

( Figs. 129 , 130 )

Typematerial. Holotype (intact ♀, MNHN-IU-2014- 21259 ) , paratype (intact ♀, MNHN-IU-2014-21260) , and dissected paratypes (♀, figured) from Diplosoma multitestis Monniot F. & Monniot C., 1996 (Holotype MNHN-IT-2008-3581 = MNHNA 2/ DIP.A/109), CRRF OCDN 1813-G, eastern Filed Atoll, 140 km southwest of Port Moresby, Papua New Guinea (10°00.66’S, 145°39.90’E), depth 20 m, 22 October 1993 .

Etymology. The specific name is derived from the Latin words acut (=sharp) and rostrum (=snout) and refers to the acutely pointed apical process on the rostrum.

Descriptionoffemale. Body ( Fig. 129A ) consisting of stout, unsegmented prosome and narrow urosome. Dorsal shield of cephalosome with slightly produced, angular posterolateral corners ( Fig. 129B ). Pedigerous somites fused but recognizable by retained dorsal tergites. Fifth pedigerous somite completely fused with fouth. Free urosome ( Fig. 129C ) 5-segmented: genitalsomite 73×162 μm, much wider than long; copulatory pore present on ventral surface. First to third abdominal somites 75×107, 87×91, and 105×75 μm, respectively. Third abdominal somite distinctly longer than wide. First and second abdominal somites ornamented with multiple rows of minute spinules on posteroventral surface. Anal somite ( Fig. 129D ) short, with pair of highly sclerotized ventral protuberances ornamented with minute spinules around apex. Caudalramus ( Fig. 129D ) slightlynarrowing distally, about 1.2 times longer than wide (27×23 μm), armedwith 3 claws and 3 setae, and ornamented with patch of minute spinules near base of proximal seta; 3 claws unequal in length and thickness, 44, 25, and 25 μm long; dorsal and outer lateral setae pinnate, ventral seta naked, all setae longerthan ramus.

Rostrum ( Fig. 129E ) 85×65 μm, tapering to acute, beak-like apical process. Antennule ( Fig. 129F ) 136 μm long and 8-segmented; armature formula 6, 10, 8+aesthetasc, 3, 3, 2, 2+aesthetasc, and 7+aesthetasc; about half of setae large and pinnate, smaller setae naked. Antenna ( Fig. 129G ) withshort, unarmedcoxa; basiswith 1 large seta representing exopod at outerdistal corner; first endopodal segment with 1 naked seta on inner margin; compound distal endopodal segment about 3.3 times longer than wide (65×20 μm), ornamented with several patches of minute spinules; armed with 9 setae plus small terminal claw, less than half length of segment.

Labrum ( Fig. 129H ) simple with slightly convex posterior margin; ornamented with setules on posteroventral surface. Mandible ( Fig. 129I ) with 5 teeth on coxal gnathobase and 2 needle-like spinules between distal second and third teeth; basis with 1 seta subdistally onmedial margin; exopod 2-segmented, armed with 3 and 2 setae on first and second segments, respectively, distalmost seta slightly shorter than other 4 setae; endopod 2-segmented and armed with 2 and 5 setae (1 medial, 3 distal, and 1 outer) on first and second segments, respectively. Maxillule ( Fig. 129J ) with 9 setae on arthrite, 1 on coxal endite, 2 on epipodite, 3 on basis, 3 onexopodand 4 on endopod. Maxilla ( Fig. 130A ) 5- segmented; syncoxa with 4, 1, 2, and 3 setae on first to fourth endites respectively; basiswith 2 setae, shorter distal seta naked; endopod with 1, 1, and 3 setae on first to third segments, respectively; 1 seta on first endite of syncoxa small, needle-like. Maxilliped ( Fig. 130B ) unsegmented and armed with 10 setae (arranged as 4, 4, and 2); mediodistal corner protruded.

	Coxa	Basis	Exopod	Endopod
Leg 1	0-0	1-I	I-1; I-1; II, I, 4	0-0; 0-1; 1, 2, 2
Leg 2	0-0	1-0	1-1; 1-1; 3, 1, 5	0-1; 0-2; 1, 2, 3
Leg 3	0-0	1-0	1-1; 1-1; 3, 1, 4	0-1; 0-2; 1, 2, 3
Leg 4	0-0	1-0	1-1; 1-1; 3, 1, 4	0-1; 0-2; 1, 2, 2

Legs 1–4 ( Fig. 130 C-F) with 3-segmented rami. Inner coxal seta absent in all legs. Inner distal spine on basis of leg 1 extending beyond distal margin of second endopodal segment, 32 μm long. Outersetaonbasis large (longer than exopod) in leg 1 butsmall inlegs 2–4. Exopods slightly longer than endopods in legs 1 and 2, but distinctly longerthan endopods inlegs 3 and 4. In legs 2–4, inner setae on first and second segments and proximal inner setaon third segment pinnate; all other setae on exopods rod-shaped with blunt tip. Outer distal corner of first and second exopodal segments trifurcate in leg 2 but bifurcate in legs 3 and 4. Armature formula for legs 1–4 as follows:

Leg 5 ( Fig. 130G ) consisting of broad protopod and small, tapering exopodal segment (13×10 μm), each tipped with 1 naked seta.

Male. Unknown.

Remarks. Periproctia acutirostris sp. nov. can be differentiated from all congeners by the possession of 3-segmented endopods in legs 1–4. In all previously described species of Periproctia the endopods of these legs are 2-segmented ( Table 3)

Figures

FIGURE 129. Periproctia acutirostris sp. nov., female.A, habitus, right; B, right posterolateral corner of cephalosome; C, urosome, ventral; D, anal somite and caudal ramus, right; E, rostrum; F, antennule; G, antenna; H, labrum; I, mandible; J, maxillule. Scale bars: A, 0.2 mm; B, 0.05 mm; C, 0.1 mm; D-J, 0.02 mm.

FIGURE 130. Periproctia acutirostris sp. nov., female. A, maxilla; B, maxilliped; C, leg 1; D, leg 2; E, exopod of leg 3; F, leg 4; G, leg 5. Scale bars: 0.02 mm.