Periproctia biunguifera, 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 : 217-220

Periproctia biunguifera sp. nov.

( Figs. 143 , 144 )

Type material. Holotype ♀ (dissected and mounted on a slide, MNHN-IU-2014-21268 ) from Eucoeliumcoronaria (Monniot F., 1988) (MNHN-IT-2008-6921 = MNHN A3/POL.B/12), Noumea, New Caledonia, Laboute coll., 1986.

Etymology. The name of the new species refers to the presence of 2 claws on the caudal ramus.

Descriptionoffemale. Body ( Fig. 143A ) narrow, 1.25 mmlong; prosomeabout 0.82 mmlong.Cephalosome well-defined. First to fourth pedigerous somites fused, discernible by retained dorsal tergites. Fifth pedigerous somite completely fused with fourth. Free urosome ( Fig. 143B ) 5-segmented, 100×160, 88×135, 96×113. 155×94, and 92×75 μm, respectively. Urosomites wellsclerotized and smooth, lacking spinular ornamentation on ventral surface. Anal somite with pair of strong ventral protuberances. Caudalramus ( Fig. 143C ) narrowing distally, about 1.2 times longerthan wide (42×35 μm): armed with 2 unequal claws and 4 setae (1 pinnate and 3 naked); larger claw 54 μm, longerthan ramus, and smaller claw 18 μm.

Rostrum ( Fig. 143E ) short, semicircular, withlarge apical tubercle. Antennule missing. Antenna ( Fig. 143D ) 4- segmented; shortcoxa unarmed; basisalso short, widerthan long, armed with 1 large pinnate seta and 1 rudimentaryseta at outer distal corner (representing exopod); first endopodal segment withlarge, naked setaon inner margin; compound distal endopodal segment about 2.4 times longer than wide (45×19 μm); armedwith 8 setae (including 1 pinnate and 3 blunt tipped setae; 1 of blunt-tipped setae very long, much longer than distal segment) plus small terminal claw, about half aslongas segment.

Labrum missing. Mandible ( Fig. 143F ) with 5 teeth and 1 smallsetaoncoxalgnathobase; basiswith 1 medial seta; exopod 2-segmented with 3 and 2 setae on first and second segments, respectively, outer distal seta on second segment small, less than half as long as other 4 setae; endopodindistinctly 2-segmentedwith 2and 5 setaeonfirst and second segments, respectively. Maxillule ( Fig. 143G ) with 7 setae on arthrite, 1 on coxal endite, 2 on epipodite, 3 onmedial margin of basis, 3 on exopod, and 4 on endopod. Maxilla ( Fig. 144A ) 5-segmented; syncoxawith 3? (setal number on first endite uncertain due to damage), 1, 2, and 3 setae on first to fourth endites, respectively; basis with 2 setae; endopod with 1, 1, and 2 setae on first to third segments, respectively. Maxilliped ( Fig. 143H ) lobate, armed with 6 medial and 2 apical setae.

Legs 1–4 ( Fig. 144 B-E) with 3-segmented exopods and 2-segmented endopods. Innercoxalsetaabsentinlegs 1–4. Outer setaon basis of leg 1 large. Inner distal spine on basis of leg 1 18 μm long, as long as first endopodal segment. First and second exopodal segments of legs 2–4 with large, dentiform outer distal process. Outer setae on first and second exopodal segments and all setae on third exopodal segment of legs 2–4 naked and bluntly tipped. First exopodal segment of leg 1 lacking inner seta. Armature formula for legs 1–4 as follows (outer seta on basis of legs 2 and 4 missing, but presence confirmed by insertion scars):

	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	1-0; 1-0; 2, 1, 5	0-1; 1, 2, 3

Leg 5 ( Fig. 144F ) as small, tapering lobe bearing 2 pinnate setae, longer seta on outer distal apex and shorter on inner margin.

Male. Unknown.

Remarks. The maxilliped of P. biunguifera sp. nov. is armed with only 8 setae and this number has been recorded previously only in P. triuncata . The arrangement of the setae is, however, different in these two species: 6 medial and 2 apical setaein P. biunguifera sp. nov., compared with 7 medial and 1 apical in P. triuncata . Another diagnostic feature of the new species is the setation of the endopod of leg 4 which carries 1 and 6 setae on the first and second segments, respectively, which is a unique character state combination within Periproctia ( Table 3). In combination, the possession of 2 claws and 4 setae on the caudal ramus, the presence of 2 setae on the third endopodal segment of the maxilla, and the loss of the inner seta from the first exopodal segment of leg 1 also serve to diagnose the new species.

Figures

FIGURE 143. Periproctia biunguifera sp. nov., female. A, habitus, right; B, urosome, dorsal; C, caudal ramus; D, antenna; E, rostrum; F, mandible; G, maxillule; H, maxilliped. Scale bars: A, 0.2 mm; B, 0.1 mm; C-H, 0.02 mm.

FIGURE 144. Periproctia biunguifera sp. nov., female. A, maxilla; B, leg 1; C, leg 2; D, exopod of leg 3; E, leg 4; F, leg 5. Scale bars: 0.02 mm.