Doroixys uncinata 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 : 460-463

Doroixys uncinata Kerschner, 1879

( Figs. 304 , 305 )

Material examined. 8 ♀♀ (MNHN-IU-2018-1893) and 1 dissected ♀ from Aplidium turbinatum (Savigny, 1816) , Roscoff, Atlantic coast of France; 1 ♀ (MNHN-IU-2018- 1894) from A. turbinatum, Roscoff ; 7 ♀♀ (MNHN-IU-2018-1895) from A. nordmanni Milne Edwards, 1841 , Greece; 5 ♀♀ (MNHN-IU-2018-1896) and 2 dissected ♀♀ from A. proliferum Milne Edwards, 1841 , SME 473, Îles d’Hyères, Mediterranean coast of France; 4 ♀♀ (MNHN-IU-2018-1897) and 1 dissected ♀ from Aplidium sp., Porto Vecchio, Corsica; 7 ♀♀ (MNHN-IU-2018-1898) and 2 dissected ♀♀ from A. nordmanni , Porto Vecchio, Corsica; 5 ♀♀ (MNHN-IU-2018-1899) and 1 dissected ♀ from A. elegans (Giard, 1872) , Tabarka, Tunisia; 5 ♀♀ (MNHN-IU-2018-1900) and 2 dissected ♀♀ (figured) from A. turbinatum, Dinard , Atlantic coast of France.

Descriptionoffemale. Body ( Fig. 304A ) inflated. Bodylength variable, 1.41 mm in figured specimen. Cephalosome clearly defined from metasome. Dorsal cephalic shield with pair of acutely pointed, sclerotized, posterolateralhorn-likeprocesses ( Fig. 304B ). Metasome incompletely 4-segmented dorsally; fourthpedigerous somite forming thin-walled brood pouch, usually moderately swollen, bulbous, but sometimes strongly swollen and almost spherical as in Fig. 304A . Free urosome ( Fig. 304C ) stout, 5-segmented. Caudal rami widely separated from each other; ramus about 3.2 times longerthan wide ( Fig. 304D ) and slightly longerthan anal somite, with blunt apex: armed with 2 middle and 4 distal setae, and ornamented with many setules; 2 middle setae positioned at 48 and 59% of ramus length.

Rostrum ( Fig. 304E ) about 80×65 μm, with almost parallel lateral margins in proximal half, tapering distally towards blunt tip; distal half irregularly ornamented with more than 10 sensillae. Antennule ( Fig. 304F ) small, 146 μmlong, 7-segmented; armatureformula 2, 15, 5, 3+aesthetasc, 2, 2+aesthetasc, and 11+aesthetasc; all setae naked and relatively short. Antenna ( Fig. 304G ) stout, 4- segmented; proximal 3 segments unarmed; basis short, shorter than first endopodal segment; compound distal endopodal segment 2.5 times longer than wide (50×20 μm): armedwith 6 setae (arranged as 1, 2, and 3) plus terminal claw 32 μm long.

Labrum ( Fig. 304H ) with broad, weakly convex free posteriormargin ornamented with dense setules; posteromedian lobe short but broad, setulose. Mandible ( Fig. 304I ) with broadened coxal gnathobase bearing 5 teeth on medial marginand 1 seta proximally; basis with 1 setaonmedial margin; exopod unsegmented, wider than long, armed with 5 setae, outermost seta small (about one-third as long as other 4 setae); endopod 2- segmented, armed with 1 and 5 setae on first and second segments, respectively; outer seta on second segment much smaller than other 4 setae. Paragnath ( Fig. 305A ) as small lobe ornamented with setules on medial margin and small spinulose lobule on outer margin. Maxillule ( Fig. 304J ) with 9 setae on arthrite (1 small), 1 each on epipodite and basis, 4 on exopod and 3 on endopod; endite absent. Maxilla ( Fig. 305B ) 4-segmented, consistingof syncoxa, basis, and 2-segmented endopod; syncoxawith 3 endites bearing 4, 2, and 2 setae on first to third endites, respectively; distal seta on first endite thin and naked; basis with strong claw ornamented with spinules on concave margin, plus 2 markedly unequal setae; endopod small bearing 1 and 3 setae on first and second segments, respectively. Maxilliped ( Fig. 305C ) unsegmented, tapering distally, armed with 5 or occasionally 6 setae; ornamented with 2 horizontal rows of spinules on lateral surface.

Legs 1–4 ( Fig. 305 D-G) biramous; coxalacking inner seta; outersetaonbasis small. Legs 1–3 with 3- segmented rami. Leg 4 with 3-segmented exopod and 2-segmented endopod. Leg 1 with small inner distal spine on basis (about half as long as first segment); first endopodal segment much broader than second and third; exopod shorter than endopod; outer setae on both rami pinnate, those of endopod markedly enlarged. Legs 2–4 with exopod longer than endopod: all setae on legs 2–4 naked and blunt tipped. Second endopodal segment of leg 4 often with vestige of articulation on outer side, occasionally absent. Armature formula for legs 1–4 as follows:

Leg 5 ( Fig. 304C ) consistingof rounded ill-defined protopod and acute, beak-like exopod: protopod tipped with small seta; exopod not articulated from protopod, sclerotized, armed with 1 small seta subdistally on outer margin.

Male. Unknown.

Remarks. In this species the form and size of the mature female body varies according to the reproductive state of the individual, since the degree of inflation of the brood pouch depends on the number of eggs it contains and their state of development. The unarmed endopod of leg 4 is a character state shared by very few other species (described below). However, this character state combined with the presence of 5 setae on the second endopodal segment of the mandible serves to differentiate thetype species, D. uncinata , from its congeners. Doroixys uncinata sensu Ooishi (1972) is treated as a new species below.

Figures

FIGURE 304. Doroixys uncinata Kerschner, 1879, female. A, habitus, right; B, posterolateral process of cephalic shield; C, leg 5 and urosome, ventral; D, right caudal ramus, ventral; E, rostrum; F, antennule; G, antenna; H, labrum; I, mandible; J, maxillule. Scale bars: A, 0.2 mm; B, 0.05 mm; C, 0.1 mm; D–J, 0.02 mm.

FIGURE 305. Doroixys uncinata Kerschner, 1879, female. A, paragnath; B, maxilla; C, maxilliped; D, leg 1; E, leg 2; F, leg 3; G, leg 4. Scale bars: A–C, 0.02 mm; D–G, 0.05 mm.