Doroixys Kerschner, 1879

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 : 459-460

Genus Doroixys Kerschner, 1879

Diagnosis. Female body moderately inflated. Dorsal cephalicshieldbearingpairof taperingposterolateralhornlike processes. Antennule at most 9-segmented. Antenna 3- or 4-segmented, with terminal claw. Mandibular exopod armed with 5 setae; mandibular endopod 2- segmented with 1 seta on first segment and 3 to 7 setae on second. Maxillule armed with 8 to 10 setae on arthrite, 1 on basis, 4 on exopod, and 3 on endopod; coxal endite typically absent; epipodite usually with 1 seta. Endopod of maxilla 2-segmentedwith 1 (occasionally 0) and 3 setae on first and second segments, respectively; occasionally 1-segmented with 3 setae. Maxilliped unsegmented, armed with at most 6 setae. Legs 1–4 biramous with 2- segmented protopod; coxalacking inner seta. Armature formula for legs 1–4 as follows (setae and spines are not differentiated):

	Coxa Basis		Exopod	Endopod
Leg 1	0-0	1-1(or 0)1-1; 1-1; 7 (or 6) 0-1; 0-1; 6
Leg 2	0-0	1-0	1-0 (or 1-1); 0-0; 0-0; 4 to
			1-0; 9	6 (or 0-0; 5)
Leg 3	0-0	1-0	1-0; 1-0; 9	0-0; 0-0; 3 to
				5 (or 0-0; 4
				or 5)
Leg 4	0-0	1-0	1-0; 1-0; 8	0-0; 0 to 4
				(or 0-0; 0-0; 0
				to 2)

Leg 1 with distinctly 3-segmented rami; basis with or without innerdistal element (spine or seta); third exopodal segment usually with 7 setal elements (occasionally 6 elements); first and second endopodal segments each bearing inner seta. Legs 2–4 lacking inner seta on first and second exopodal segments, except few species bearing inner seta on first segment only. Endopods of legs 2–4 slender; setae present only on terminal segment (endopod occasionally unarmed). Leg 5 with sclerotized, horn-like process (vestige of exopodal segment) usually bearing 1 small seta. Associated with compound ascidians.

Type species: Doroixys uncinata Kerschner, 1879 , by original monotypy.

Remarks. The genus Doroixys currently comprises five nominal species, D. bispinosa Ooishi, 1998 , D. capillosus Ho & Kim I.H., 2009 , D. minuta Stock, 1970 , D. simplex Marchenkov & Boxshall, 2004 , and D. uncinata . As Marchenkov & Boxshall (2004) mentioned, the genus was indistinctly defined when originally established ( Kerschner, 1879). Nevertheless, the original illustrations of the type species given by Kerschner (1879) display important morphological information that allows us to redefine the genus. It should be pointed out here that Kerschner’s Fig. 8 (leg 2) in Plate Vwas erroneously labelledasleg 3inthetextand Fig.9 (leg4) waserroneously labelled as leg 3 in the figure legend. Based on his figures for legs 1, 2, and 4, the type species displays a limited reduction of the setation on leg 1 (on third exopodal segment). In contrast, legs 2–4 of this species reveal remarkable reductions of armature elements: the loss of the inner seta on proximal segment(s) of the exopod and endopod. In the endopods of legs 2–4, only the terminal segment is armed with seta(e), and in some cases there are no setae at all on the endopod. Acomparison between D. uncinata and the many new species described below in the present work reveals that the above characteristics of the legs are combined with other diagnostic features at the generic level, as follows: (1) dorsal cephalic shield and leg 5 bearing horn-like processes; (2) mandible with broadened coxal gnathobase bearing 5 teeth; (3) maxillule with 1 seta on basis, but mostly lacking coxal endite; (4) endopod of maxilla typically 2-segmented, with welldevelopd claw on basis; and (5) maxilliped unsegmented and armed with fewer than 7 setae (generally 5 or 6 setae). The combination of these features allows us to define the genus Doroixys . Known species of this genus are distributed in both tropical and warm temperate waters.

Three of the current species, D. bispinosa , D. capillosus , and D. simplex , do not share the characteristics outlined above in the revised diagnosis of Doroixys and are here removed to other genera.

Figures

FIGURE 8. Notodelphys allmani Thorell, 1859, female. A, habitus, dorsal; B, urosome, ventral; C, left caudal ramus, ventral; D, antennule; E, rostrum; F, antenna; G, labrum; H, mandible; I, maxillule; J, paragnath. Scale bars: A, 0.5 mm; B, 0.2 mm; C–J, 0.05 mm.

FIGURE 9. Notodelphys allmani Thorell, 1859, female. A, maxilla; B, maxilliped; C, leg 1; D, leg 2; E, leg 4; F, leg 5. Scale bars: 0.05 mm.