Doroixys pilosa, 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 : 486-491

Doroixys pilosa sp. nov.

( Figs. 324 , 325 )

Typematerial. Holotype (intact ♀, MNHN-IU-2014- 21374 ) , paratype (intact ♀, MNHN 0IU-2014-21375), anddissectedparatype (♀, figured) from Eudistoma gilboviride (Sluiter, 1909) (MNHN-IT-2008-4052 = MNHN A3/ EUD /88), CRRFOCDN 0678-U, Rasch Passage, Papua New Guinea (05°09.27’S, 145°49.82’E), depth 3 m, 04 November 1993.

Etymology. The specific name is from the Latin pilos (=hairy) and refers to the dense ornamentation of minute setules covering the body.

Descriptionoffemale. Body ( Fig. 324A ) stout, bearing numerous minutesetules on external surface (ornamentation not shown in Fig. 324A ): body length 1.39 mm. Prosome 1.05 mm long: dorsalcephalic shield bearing prominent, paired dorsally-curved, hornlikeprocesses posterolaterally ( Fig. 324B ). Metasome incompletely 4-segmented; fourth pedigeroussomite swollen, forming brood pouch. Freeurosome ( Fig. 324C ) 5-segmented, graduallynarrowingposteriorly, covered with minute setules: genital and 4 abdominal somites 64×173, 64×156, 49×122, 36×105, and 64×91 μm, respectively. Caudalramus ( Fig. 324D ) tapering, 2.85 times longer than wide (77×27 μm): armed with 6 setae; outer lateral and dorsal setae positioned at 59 and 66% of ramus length, respectively; all setae small, at most half as long as width of ramus at base.

	Coxa	Basis	Exopod	Endopod
Leg 10-0	10-0	1-I	I-1; I-1; I+1, 2, 3	0-1; 0-1; 1, 2, 3
Leg 20-0	20-0	1-0	1-0; 1-0; 3, 1, 5	0-0; 0-0; 1, 2, 3
				(or 0, 2, 3)
Leg 30-0	30-0	1-0	1-0; 1-0	0-0; 0-0; 1, 2, 2
			(or 1-1); 3, 1, 5	(or 0, 2, 2)
Leg 40-0	40-0	1-0	1-0; 1-0; 3, 1, 4	0-0; 1, 2, 0

Rostrum( Fig.324E )setulose,longerthanwide(98×60 μm), with parallel lateral margins in proximal third, but tapering steeply in distal two-thirds towards angular apex. Antennule ( Fig. 324F ) 147 μmlong, stronglytapering, 8-segmented, but articulation incomplete between last 2 segments: armatureformula 2, 14, 6, 3+aesthetasc, 2, 2+aesthetasc, 4, and 7+aesthetasc; all setae naked. Antenna ( Fig. 324G ) 3-segmented, consistingof unarmed coxa and basis and unsegmented endopod; endopod as long as basis and about 2.6 times longerthan wide (50×19 μm), ornamented with few setules: armed with 5 small setae (arranged as 1, 2, and 2) plus terminal claw slightly less than half length of endopod.

Labrum ( Fig. 324H ) bearing broad, convex, setulose posterior margin. Mandible ( Fig. 324I ) with broad coxal gnathobase bearing 5 teeth and 1 seta: basis unarmed, lacking medial seta: exopod short, armedwith 4 large subequal setae and 1 small outer seta (about 25% as long as larger setae): endopod 2-segmented; first segment with 1 broad seta mediodistally; second segment with 5 or 4 setae, smallest outer seta (indicated by arrowhead) present or absent. Maxillule ( Fig. 324J ) armed with 9 setae on arthrite, 1 on epipodite, 1 on basis, 4 on exopod and 3 on endopod; coxal endite absent. Maxilla ( Fig. 324K ) 3-segmentedwith 1-segmented endopod: armed with 4, 2, and 2 setae on first to third endites of syncoxa, respectively, clawplus 1 setaon basis, and 3 setaeon endopod; claw on basis ornamented with minute spinules along distal third of concave margin. Maxilliped ( Fig. 324L ) unsegmented, armedwith 6 setae, and ornamented with 2 transverse rows of spinules on outer surface.

Legs 1–3 ( Fig. 325 A-C) with 3-segmented rami. Leg 4 ( Fig. 325D ) with 3-segmented exopod and 2-segmented endopod; compound distal endopodal segment of leg 4 bearing trace of articulation in middle. Inner coxal seta absent in all legs. Inner distal spine on basis of leg 1 small, 15 μm long. Distal seta on third exopodal segment of leg 1 broadened. All setae on rami of legs 2–4 bluntly tipped. Outer seta on third endopodal segment of legs 2 and 3 present or absent. Inner seta on second exopodal segment of leg 4 also present or absent.

Leg 5 ( Fig. 325E ) represented by outer protopodal seta on ventrolateral margin of somite plus tapering, pointed inner exopodal process bearing 1 seta subdistally on outer margin.

Male. Unknown.

Remarks. The setation of the swimming legs and the mandibular endopod are unreliable for characterising Doroixys pilosa sp. nov. due to the variability exhibited between specimens. Instead, this new species exhibits a remarkable autapomorphic feature, the single-segmented endopod of the maxilla. The combination of this feature with the lack of a seta on the mandibular basis and the relative lengths of the setae on the mandibular exopod (small outermost seta and 4 other equally large setae) allows this new species to be separated from all of its congeneric species.

Figures

FIGURE 324. Doroixys pilosa sp. nov., female. A, habitus, right; B, cephalic horn; C, leg 5 and urosome, ventral; D, left caudal ramus, dorsal; E, rostrum; F, antennule; G, antenna; H, labrum; I, mandible; J, maxillule; K, maxilla; L. maxilliped. Scale bars: A, 0.2 mm; B, D–L, 0.02 mm; C, 0.1 mm.

FIGURE 325. Doroixys pilosa sp. nov., female. A, leg 1; B, leg 2; C, leg 3; D, leg 4; E, left and right legs 5. Scale bars: 0.05 mm.