Periproctia laticaudata, 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 : 231

Periproctia laticaudata sp. nov.

( Figs. 153 , 154 )

Typematerial. Holotype (intact ♀, MNHN-IU-2014- 21275 ) , paratypes (2 intact ♀♀, MNHN-IU-2014-21276) , and dissected paratypes (2 ♀♀, figured) from Didemnum psammatodes (Sluiter, 1895) , Îles Mesha Maree, Djibouti, Monniot coll., 13 October 1996.

Etymology. The specific name is derived from the Latin lati (=broad) and cauda (tail), referring to the broad abdomen of the new species.

	Coxa	Basis	Exopod	Endopod
Leg 1	0-0	1-I	I-0; 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; 1-0; 2, 1, 5	0-1; 1, 2, 5
Leg 4	0-0	1-0	1-1 (or 1-0);	0-0; 1, 2, 3
1-0; 2, 1, 5

Descriptionoffemale. Body ( Fig. 153A ) small, 670 μm long. Prosome 500 μm long and dorsoventral depth 210 μm. First to fourth pedigerous somites fused forming brood pouch. Fifth pedigerous somite completely fused with fourth. Freeurosome ( Fig. 153B ) stout, 5-segmented; all urosomites much wider than long: genital somite 27×108 μm, with copulatory pore on ventral surface. Four abdominalsomites 20×81, 23×70, 36×60, and 27×51 μm, respectively; first to third abdominal somites ornamented with rows of minute spinules on ventral surface. Anal somite ( Fig. 153C ) bearing pair of ventral protuberances densely covered with minute spinules; anal operculum distinct. Caudalramus 17×17 μm, narrowing distally, armed with 3 claws and 3 naked setae, and ornamented with spinules near base of proximal seta; lengths of claws 21, 15, and 15 μm.

Rostrum ( Fig. 153D ) triangular, 55×45 μm, evenly tapering towards small beak-like process at apex. Antennule ( Fig. 153E ) 87 μm long and 7-segmented; armatureformula 6, 17+aesthetasc, 3, 2+aesthetasc, 2, 2+aesthetasc, and 7+aesthetasc; all setae naked. Antenna ( Fig. 153F ) ratherslender, 4-segmented; coxashortand unarmed; basis longerthan wide, with 1 large outer distal seta representing exopod; first endopodal segment longer than wide, with 1 naked seta on inner margin; compound distal endopodal segment about 3.7 times longer than wide (48×13 μm), 1.5 timeslongerthan first endopodal segment, armed with 6 naked setae (grouped as 1, 2, and 3) plus small terminal claw, less than half as long as segment.

Labrum missing. Mandible ( Fig. 153G ) similarto that of P. hexachaetata sp. nov., with 2 and 5 setae on first and second endopodal segments, respectively. Maxillule ( Fig. 153H ) with 6 setae on arthrite, 1 on coxal endite, 2 on epipodite, 2 on medial margin of basis, 3 on exopod and 4 on endopod. Maxilla ( Fig. 154A ) 5-segmented; syncoxa with 3, 1, 2, and 3 setae on first to fourth endites, respectively; basiswith 2 setae; endopodwith 1, 1, and 2 setae on first to third segments, respectively. Maxilliped ( Fig. 153I ) armed with 7 (4+3) medial and 1 apical setae.

Legs 1–4 ( Fig. 154 B-E) with 3-segmented exopods and 2-segmented endopods. Outer seta on basis of leg 1 longerthan exopod. Innerdistalspineonbasisofleg 1 slightly longer than first endopodal segment. In leg 2, inner seta on first endopodal segment and proximalmost inner seta on second endopodal segment elongate. Second exopodal segments of legs 3 and 4 lacking inner seta. Inner seta on first exopodal segment present in right leg 4, but absent in left leg 4. Outer distal process of first and second exopodal segments of legs 2–4 variable, simple, bifurcate, or trifurcate. Armature formula for legs 1–4 as follows:

Leg 5 ( Fig. 153B ) consistingof broad, tapering protopod tipped with 1 feebly pinnate seta and small, free exopod with naked apical seta.

Male. Unknown.

Remarks. In having only 2 medial setae on the basis of the maxillule, P. laticaudata sp. nov. resembles P. biuncata and P. angusta sp. nov., but itis easily distinguishable from these two species, because there are 7 setae on the maxilliped of P. biuncata and 10 setae in P. angusta sp. nov., whereas the maxilliped of P. laticaudata sp. nov. is armedwith 8 setae (vs. 7 medial and 1 apical). This armature of the maxilliped was previously known only in P. triuncata , but this species differs from P. laticaudata sp. nov. in various other character states, for example, the first exopodal segment of leg 1 bears an inner seta (vs. this seta is absent in P. laticaudata sp. nov.), the secondendopodal segment of leg 1 bears 5 setae (vs. 6 setae in P. laticaudata sp. nov.), and the second exopodal segment of leg 3 lacks an inner seta (vs. this seta is present in P. laticaudata sp. nov.).

Figures

FIGURE 153. Periproctia laticaudata sp. nov., female. A, habitus, right; B, urosome, ventral; C, anal somite and caudal ramus, right; D, rostrum; E, antennule; F, antenna; G, mandible; H, maxillule; I, maxilliped. Scale bars: A, 0.1 mm; B-I, 0.02 mm.

FIGURE 154. Periproctia laticaudata sp. nov., female. A, maxilla; B, leg 1; C, leg 2; D, exopod of leg 3; E, leg 4. Scale bars: 0.02 mm.