Doroixys parvicaudata, 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 : 469-472

Doroixys parvicaudata sp. nov.

( Figs. 310 , 311 )

Typematerial. Holotype (intact ♀, MNHN-IU-2014- 21363 ) , intact paratypes (3 ♀♀, MNHN-IU-2014-21364), anddissectedparatype (♀, figured) from Polyclinum macrophyllum Michaelsen, 1919 , Mont Dore, New Caledonia, NC 46, Monniot coll., 19 March 1987.

Additional material. 1 ♀ (dissected) from P. macrophyllum, Îlot Maître Mont Dore, NC 16, New Caledonia, depth 5 m, 12 September 1985.

Etymology. The specific name is derived from Latin parv (=small) and cauda (=tail) and refers to the relatively small caudal rami.

Descriptionoffemale. Body ( Fig. 310A ) stout, 1.32 mm long. Prosome bulbous, 1.00 mm long: dorsal cephalic shield bearing pair of small, narrow claw-like processes ( Fig. 310B ) posterolaterally. Metasomeunsegmented, broadening posteriorly, with 3 vestigial tergites dorsally marking first to third pedigerous somites; fourth pedigeroussomite swollen, forming brood pouch, with straight ventral margin and rounded dorsal and posterior margins. Freeurosome ( Fig. 310C ) small, 5-segmented: all urosomites much wider than long: genital somite narrowing anteriorly, 55×156 μm; 4 abdominalsomites 58×145, 47×127, 44×118, and 65×95 μm, respectively. Anal somite rectangular, lacking posteromedian incision. Caudal rami ( Fig. 310C ) small, fusiform, widely separated from each other; each ramus ( Fig. 310D ) about 2.5 times longerthan wide (59×22 μm) and shorter than anal somite: armed with 1 outer, 1 dorsal and 4 distal setae; all setae shorter than width at base of ramus; outer and dorsal setae positioned at 43 and 58% of ramus length, respectively.

Rostrum ( Fig. 310E ) well-developed, 86×77 μm, tapering towards rounded apex. Antennule ( Fig. 310F ) 147 μmlong, 9-segmented; armatureformula 2, 12, 5, 2+aesthetasc, 1+aesthetasc, 4+aesthetasc, 2, 2+aesthetasc, and 7+aesthetasc; all setae naked; aesthetascs small and setiform. Antenna ( Fig. 310G ) 4-segmented; proximal 3 segments unarmed; basis shorter than first endopodal segment; compound distal endopodal segment about 3.1 times longer than wide (52×17 μm) and as long as first endopodal segment: armedwith 5 setae (arranged as 1, 2, and 2) plus small terminal claw, about 0.4 times as long as segment.

Labrum ( Fig. 310H ) simple, setulose along evenly convex posterior margin. Mandible ( Fig. 310I ) with 5 teeth and 1 setaon coxal gnathobase; setae on palp relatively short, 1 on basis, 5 on exopod, 1 and 5 on first and second endopodal segments, respectively; outer seta on exopod small, one-third as long as other 4 exopodal setae. Maxillule ( Fig. 310J ) armedwith 9 setaeon arthrite, 1 on epipodite, 1 on basis, 4 onexopodand 3 on endopod; 3 setae on endopod equal in length. Maxilla ( Fig. 310K ) 4-segmented; syncoxa with 4, 2, and 2 setae on first to third endites, respectively; basis with strong, naked claw plus 1 seta; endopod with 1 and 3 naked setae on first and second segments, respectively. Maxilliped ( Fig. 8A ) as tapering lobe armed with 6 setae (4 medial and 2 apical) and ornamented with 3 rows of spinules on outer surface.

Legs 1–3 ( Fig. 311 B-E) with 3-segmented rami. Leg 4 ( Fig. 311F ) with 3-segmented exopod and 2-segmented endopod. Inner coxal seta absent in all swimming legs. Inner distal spine on basis of first leg 20 μm long. Setae on leg 1 pinnate except outer setaon third exopodal segment. Third exopodal segment of legs 2–4 (except that of right leg 3) more than twice as long as wide. All setae on legs 2–4 naked and bluntly tipped. First endopodal segment of legs 2 and 3 broadened. Second endopodal segment of leg 2 with convex inner margin and shorter, straight outer margin. Outer seta (indicated by arrowhead in Fig. 311C ) on third endopodal segment of leg 2 present or absent. Left and right leg 3 asymmetrical: right leg 3 stouter with shorter setae than in left leg 3 (cf. Fig. 311D and 311E ). Armature formula for legs 1–4 as follows:

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

Leg 5 ( Fig. 311G ) consisting of outer and inner lobes located posteroventrally on brood pouch; outer protopodal lobe tipped with 1 seta; inner exopodal lobe not articulated at base, terminating in dentiform process, with convex outer and inner margins, and armed with 1 seta subdistally on outer margin

Male. Unknown.

Remarks. The endopods of legs 3 and 4 are 3- and 2-segmented, respectively, and are armed with 4 and 3 setae on the terminal segment, respectively. This leg segmentation and armature of D. parvicaudata sp. nov. is shared with D. ooishiae sp. nov. but these two species can be readily distinguished by the presence of an inner seta on the first exopodal segment of leg 2 in D. ooishiae sp. nov. (vs. absentin D. parvicaudata sp. nov.). There are additional differences: in D. ooishiae sp. nov. the outer protopodal lobe of leg 5 is extended, the third exopodal segment of legs 2–4 is only slightly longer than wide, and the body, antennule, antenna, and swimming legs are all setulose, as illustrated by Ooishi (1972). These surfaces are not setulose in D. parvicaudata sp. nov.

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 310. Doroixys parvicaudata sp. nov., 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; K, maxilla. Scale bars: A, 0.2 mm; B, D–K, 0.02 mm; C, 0.05 mm.

FIGURE 311. Doroixys parvicaudata sp. nov., female. A, maxilliped; B, leg 1; C, left leg 2 (seta marked by arrowhead absent in some specimens); D, left leg 3; E, right leg 3; F, left leg 4; G, leg 5. Scale bars: 0.05 mm