Campodelphys seticoxus, 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 : 600-603

Campodelphys seticoxus gen. etsp. nov.

( Figs. 404 , 405 )

Type material. Holotype ♀ (dissected and mounted on a slide, MNHN-IU-2014-21435 ) from Eudistoma reginum Kott, 1991 (MNHN-IT-2008-4187 = MNHN A3/EUD/75), CRRFOCDN 1434-S, Manado, north Sulawesi, Indonesia, depth 60 m, 21 May 1993.

Etymology. The specific name refers to the presence of the inner seta on the coxa of leg 4.

Descriptionoffemale. Body ( Fig. 404A ) slender, cylindrical, slightlycurvedventrally;bodylength2.10mm. Prosome unsegmented; anterior fifth tapering anteriorly and posterior third tapering posteriorly; anterior region from rostrum to level of leg 4 occupying about one-third of length of prosome. Cephalosome ( Fig. 404B ) defined from metasome by weak lateral constriction, bearing prominent paired tubercles posterolaterally on ventral surface. Freeurosome ( Fig. 404C, D ) 5-segmented, strongly curved ventrally. Genital somite narrower than anterior abdominal somites.Anal somite ornamented with row of spinules along posteroventral margin ( Fig. 404E ). Caudal ramus ( Fig. 404E ) as long as anal somite and twice as long as wide (45×22 μm): armed with 6 naked setae (1 outer lateral, 1 dorsal, and 4 distal) and ornamented with scattered stiff setules.

Rostrum ( Fig. 404B ) directed anteroventrally, tipped with narrow tubercle. Antennule ( Fig. 404F ) short and broad, 75 μm long, divisible into 5 segments by 4 partial articulations on posterior surface; first segment bearing 2 setae, setation of other segments not discernible due to dense packingof setae.Antenna ( Fig. 404G ) 3-segmented, consisting of coxa, basis, and unsegmented endopod; basis about 1.7 timeslongerthan wide, unarmed; endopod about 2.3 times longer than wide (27×12 μm); armed with 8 smallsetae (arranged as 3, 2, and 3), plus terminal claw aslongas endopod.

Labrum missing. Mandible ( Fig. 404H ) with narrow coxal gnathobase; medial margin of gnathobase pectinate, with 2 denticles distally (distal denticle much smaller than subdistal); palp armed with 1 setaon basis, 4 on exopod, and 1 and 4 on first and second endopodal segments, respectively; all setae naked. Maxillule ( Fig. 404I ) as digitiform lobe bearing 7 pinnate setae (2 medial, 3 distal, and 2 outer). Maxilla ( Fig. 404J ) as tapering lobe bearing 6 pinnate setae (3 medial, 2 distal, and 1 outer). Maxilliped ( Fig. 404K ) unsegmented with 2 small, proximally-directed setae subapically.

Legs 1–4 ( Fig. 405 A-D) biramous, each with incompletely 2-segmented protopod, 2-segmented exopod, and unsegmented endopod. Coxa of leg 4 characteristically with inner seta (indicated by arrowhead in Fig. 405D ). Basis of legs 1–4 with outer seta. Basis of leg 1 with spiniform inner distal seta. First exopodal segment of legs 1–4 with 3 or 4 thick setules on outer margin. Setae on rami spiniform and usually blunt, but 2 proximal setaeon exopods of legs 2–4 pinnate and attenuate. Armature formula for legs 1–4 as follows:

	Coxa	Basis	Exopod	Endopod
Leg 1	0-0	1-1	1-0; 7	6 (or 7)
Leg 2	0-0	1-0	1-1; 10	8
Leg 3	0-0	1-0	1-1; 11	9
Leg 4	0-1	1-0	1-1; 10	8

Leg 5 ( Fig. 404C, D ) represented by 2 small setae on posteroventral surface of prosome.

Male. Unknown.

Remarks. Campodelphysseticoxus gen. etsp. nov. resembles C. ancylocephalus gen. et sp. nov. in having unsegmented endopods in all swimming legs and an inner distal seta on the basis of leg 1. However, they differ in the numbers of setaeon the maxillule, maxilla, maxilliped, and swimming legs. It is noteworthy that the presence of the inner seta on the coxa of leg 4 of C. seticoxus gen. et sp. nov. is a unique feature within the genus.

Figures

FIGURE 404. Campodelphys seticoxus sp. nov., female. A, habitus, right; B, cephalosome, ventral; C, urosome, ventral; D, urosome, right; E, caudal rami, ventral; F, antennule; G, antenna; H, mandible; I, maxillule; J, maxilla; K, maxilliped. Scale bars: A, 0.2 mm; B–D, 0.05 mm; E, 0.02 mm; F–K, 0.01 mm.

FIGURE 405. Campodelphys seticoxus sp. nov., female. A, leg 1; B, leg 2; C, leg 3; D, leg 4. Scale bars: 0.02 mm.