Procampodelphys nodosus, 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 : 586

Procampodelphys nodosus gen. et sp. nov.

( Figs. 393 , 394 )

Type material. Holotype ♀ (dissected and mounted on a slide, MNHN-IU-2014-21427 ) from an unidentified ascidian, near the lighthouse , Ibo Island, Mozambique, depth 0-20 m, AURACEA 1995 Stn P15, Monniot coll., 14 November 1995.

Etymology. The specific name is from the Greek nod (=toothless) and alludes to the lack of teeth on the distal margin of the mandibular coxa.

Descriptionoffemale. Body ( Fig. 393A ) caterpillarlike, weakly curved ventrally, surface densely covered with fine setules (setules omitted in Fig. 393A ). Body length 2.36 mm; width 567 μm. Cephalosome ( Fig. 393B ) indistinctly defined from metasome. Metasome cylindrical, with weak constriction between first pedigerous somite and remaining part of metasome. Freeurosome ( Fig. 393C ) indistinctly 3-segmented in ventral view, but with additional suture line in dorsal view; ornamented with scattered setules on all surfaces; first urosomite with copulatory pore on ventral surface. Caudal rami ( Fig. 393D ) about 1.3 times longerthan wide (59×44 μm), not articulated from anal somite; armed with 6 small setae and scattered setules.

Rostrum ( Fig. 393E ) linguiform with rounded distal margin, about 70×50 μm, densely covered with setules. Antennule ( Fig. 393F ) small, about 90 μmlong, unsegmented, curved, strongly tapering, covered with setules and armed with 16 setae. Antenna ( Fig. 393G ) 3- segmented;coxaandbasisunarmed;unsegmentedendopod as long as basis, 2.3 times longerthan wide (44×19 μm); ornamented with large patch of minute spinules distally on inner surface and several spinules distally on outer margin; armed with 7 small setae arranged as 2, 2, and 3 (2 of distal setae spinulose along inner margin), plus small terminal claw, about one-third as long as endopod.

Labrum missing. Mandible ( Fig. 393H ) consisting of coxa and palp: coxal gnathobase with linear, pectinate medial margin and convex distal margin: palp armed with 1 setaon basis, 4 large setaeon exopod, and 1 and 4 setae on first and second endopodal segments, respectively; articulation incomplete between basis and endopod. Maxillule ( Fig. 393I ) unsegmented and bilobed; inner lobe (precoxal arthrite) extending beyond outer lobe and armed with 3 setae (proximal seta larger than 2 distal setae); outer lobe armed with 5 setae, proximalmost seta swollen at base and second proximal seta longest. Maxilla ( Fig. 393J ) distinctly 3-segmented; syncoxawith 2 large pinnate setae; basiswith 1 naked seta; endopod with 1 pinnate and 2 naked setae. Maxilliped ( Fig. 393K ) unsegmented, armed with 7 setae on medial margin; distalmost seta swollen, plumose, bluntly tipped; spinules present near base of distalmost seta; proximal 6 setae subequalin length, proximal 2 pinnate, other 4 setae naked.

Legs 1–4 ( Fig. 393L , 394 A-C) bilobed with unsegmented protopods; rami setulose and obscurely defined from protopod; endopods smaller than exopods. Outer seta on protopods well-developed, naked in leg 1, but pinnate in legs 2–4. Endopod of leg 4 rudimentary. Protopod of leg 1 with inner proximal seta (original inner coxal seta) and inner distal seta (original inner distal seta of basis). Protopod of leg 1 with short spinule row along inner margin. Exopods of legs 1–4 armedwith 7, 6, 5, and 4 setae, respectively. Endopods of legs 1–4 armed with 6, 8, 6, and 4 setae, respectively. Leg 4 with 1 seta on protopod medial to endopod. Leg 5 represented by 1 minute seta ( Fig. 393A, C ) on ventrodistal surface of metasome.

Male. Unknown.

Remarks.Thediagnosticfeaturesof Procampodelphys nodosus gen. et sp. nov. include: the antennule is unsegmented, the distal margin of the gnathobase of the mandibular coxa is smooth (lacking denticles), the precoxal arthrite of the maxillule bears 3 setae, and the maxilliped is armed with 7 setae of which the distalmost is bluntly tipped. These features serve to differentiate the new speciesfrom the type species P. bidentatus gen. et sp. nov., which is characterised by a 2-segmented antennule, by the presence of 2 denticles on the distal margin of the coxal gnathobase of the mandible, 4 setae on the precoxal arthrite, and 6 setaeon the maxilliped (with the distalmost seta terminating in a thin flagellate section).

Aremarkable and fine-scale synapomorphy between P. nodosus gen. etsp. nov., P. bidentatus gen. etsp. nov., and P. biramus is the peculiar maxilliped in which all setae are inserted on the medial margin of the lobate appendage and the base of the distalmost seta is inflated and plumose distally. The retention of the inner coxal seta on leg 1 is an extraordinarily plesiomorphic state for such a highly transformed parasite. The isolated seta present medial to the endopod on the incorporated protopod of leg 4 may represent the original inner coxal seta of leg 4.

Figures

FIGURE 393. Procampodelphys nodosus gen. et sp. nov., female. A, habitus, right; B, cephalosome, dorsal; C, urosome, ventral; D, caudal rami, ventral; E, rostrum; F, antennule; G, antenna; H, mandible; I, maxillule; J, maxilla; K, maxilliped; L, leg 1. Scale bars: A, 0.2 mm; B, C, 0.1 mm; D, 0.05 mm; E–I, L, 0.02 mm.

FIGURE 394. Procampodelphys nodosus gen. et sp. nov., female. A, leg 2; B, leg 3; C, leg 4. Scale bars: 0.02 mm.