Periproctia onchopodata, 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 : 227-228

Periproctia onchopodata sp. nov.

( Figs. 149 , 150 )

Typematerial. Holotype (intact ♀, MNHN-IU-2014- 21273 ) anddissectedparatype (♀, figured) from Eudistoma amplum (Sluiter, 1909) (MNHN-IT-2008- 3954 = MNHNA 3/ EUD /151), CRRFOCDN 2841-W, Palau (07°15.08’N, 134°24.62’E), east of Ngeruktabel, Long Lake, depth 1 m, 20 June 1995.

Etymology. The specific name is a combination of Greek words onch (=tubercle) and pod (=a foot). It alludes to the large tubercle at the outer distal corner of the coxa of leg 1.

Descriptionoffemale. Body ( Fig. 149A ) narrow, archedventrally,1.54mmlong.Prosomeslightlydepressed, distinctly segmented, 1.20 mm long, with parallel lateral margins. Fifth pedigerous somite completely fused with fourth. Freeurosome ( Fig. 149B ) graduallynarrowing posteriorly, 5-segmented: genitalsomite 58×187 μm, with small copulatory pore on ventral surface. Four abdominalsomites 65×162, 67×142, 102×120, and 45×85 μm, respectively. First to third abdominal somites each ornamented with rows of minute spinules ventrally. Anal somite ( Fig. 149C ) short, with pair of spinulose ventral protuberances; anal operculum well-developed. Caudalramus ( Fig. 149C ) about 1.2 timeslongerthan wide (42×34 μm), slightlynarrowing distally: armedwith 1 large and 2 smaller claws and 3 naked setae; patch of spinules present near base of proximal seta; lengths of claws 59, 29, and 25 μm; setae shorter than ramus.

	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	1-0; 1-0; 2, 1, 5	0-0; 1, 2, 4
Leg 4	0-0	1-0	1-0; 1-0; 2, 1, 5	0-0; 1, 2, 2

Rostrum ( Fig. 149D ) longerthanwide (106×75 μm), widest in middle and narrowing both proximally and distally, with papilla at each proximal corner and small beak-like apical process. Antennule ( Fig. 149E ) stout, 155 μmlong, and 8-segmented; armatureformula 5, 9, 8+aesthetasc, 3, 2+aesthetasc, 2, 2+aesthetasc, and 7+aesthetasc; pinnate setae 4 on first segment, 4 on each second and third, and 1 on fourth; aesthetasc on third segment swollen proximally. Antenna ( Fig. 149F ) 4-segmented; coxa short and unarmed; basis with large exopodal seta at outer distal corner; first endopodal segment with 1 seta on inner margin; compound distal endopodal segment 3.0 times as long as wide, ornamented with rows of spinules on both margins; armed with 8 setae plus small terminal claw, less than half length of segment.

Labrum ( Fig. 149G ) characteristically with parallel lateral margins and convex posterior margin ornamented with 4 groups of setules. Mandible ( Fig. 149H ) comprising coxa and palp; coxa bearing 5 teeth, including 2 small proximal ones, 1 small seta on proximal margin, and 1 needle-like spinules between second and third distal teeth; basiswith 1 setaonmedial margin; exopod 3-segmented and armed with 2, 1, and 2 setaeon first to third segments, respectively; outer distal seta on third exopodal segment small, less than half length of other 4 setae; endopod armed with 2 and 5 setae on first and second segments, respectively. Maxillule ( Fig. 149I ) with 9 setaeon arthrite, 1 seta on coxal endite and on epipodite; basis, exopod and endopod with 3, 3, and 4 setae, respectively. Maxilla ( Fig. 150A ) 5-segmented; syncoxa and basis with 9 and 2 setae, respectively, as usual; endopodwith 1, 1, and 2 setae on first to third segments, respectively. Maxilliped lobate ( Fig. 150B ) armed with 8 medial and 2 apical setae; ornamented with several rows of minute spinules on surface.

Legs 1–4 ( Fig. 150 C-F) each with 3-segmented exopod and 2-segmented endopod. Leg 1 bearing large globular tubercle ornamented with long setules at outer distal corner of coxa (arrowhead in Fig. 150C ); outer seta on basis large; inner distal spine on basis longer than first endopodal segment, 31 μm long; first exopodal segment bearing 2 blunt denticles at outer distal corner. First and second exopodal segments of legs 2–4 each with bifid outer distal corner. Inner seta absent on first and second exopodal segments and first endopodal segment of legs 3 and 4. Outer seta (indicated by arrowhead in Fig. 150D ) on second endopodal segment of leg 2 small and pinnate. Same seta in legs 3 and 4 also small but naked. Armature formula for legs 1–4 as follows:

Leg 5 ( Fig. 149B ) represented by 2 digitiform lobes on posteroventral margin of compound fourth/fifth pedigerous somite; each lobe tipped with pinnate seta.

Male. Unknown.

Remarks. The presence of the large globular tubercle at the outer distal corner of the coxa of leg 1 is a feature unique to P. onchopodata sp. nov. The armature pattern of the legs of the new species is also characteristic since it lacks an inner seta on the first exopodal segment of leg 1 (this feature is shared with P. bisetigera sp. nov. and P. biunguifera sp. nov.), lacks an inner seta on the first and second exopodal segments of leg 3 (a unique setation pattern within Periproctia ), and lacks an inner seta on the first and second exopodal segments of leg 4 (a feature shared with P. biuncata and P. longirostris sp. nov.). The possession of only 5 setae on the second endopodal segment of leg 4 also is an unusual feature which is shared only by P. spinata sp. nov. and P. onchopodata sp. nov. ( Table 3).

Figures

FIGURE 149. Periproctia onchopodata sp. nov., female. A, habitus, dorsal; B, urosome, ventral; C, anal somite and caudal ramus, left; D, rostrum; E, antennule; F, antenna; G, labrum; H, mandible; I, maxillule. Scale bars: A, 0.2 mm; B, 0.1 mm; C-E, I, 0.02 mm; F-H, 0.05 mm.

FIGURE 150. Periproctia onchopodata sp. nov., female. A, maxilla; B, maxilliped; C, leg 1; D, leg 2; E, leg 3; F, leg 4. Scale bars: A, B, 0.02 mm; C-F, 0.05 mm.