Notodelphys weberi Stock, 1950

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 : 41-44

Notodelphys weberi Stock, 1950

( Figs. 24 , 25 )

Material examined. 1 ♀ (dissected and figured) from Ascidia canaliculata Heller, 1878 , Knysna, South Africa, February 1996.

Supplementary description of female. Body ( Fig. 24A ) depressed, 2.94 mm long. First pedigerous somite only slightly narrower than second and third pedigerous somites. Brood pouch longer than wide, 1.04×0.87 mm with weakly convex lateral margins; fifth pedigerous somite completely fused to brood pouch. Free urosome ( Fig. 24B ) 5-segmented; genital and abdominal somites 177×259, 218×266, 227×257, 182×232, and 150×205 μm, respectively. Caudal ramus about 3.3 times as long as wide (208×63 μm), setulose along inner and outer margins, and armed with 6 pinnate setae; outer lateral seta positioned at 67% of ramus length.

Rostrum ( Fig. 58A ) longerthan wide, tapering to small apical lobe. Antennule ( Fig. 24C ) shorter than cephalosome, 15-segmented; armatureformula 3, 5, 12, 6, 4+aesthetasc, 2, 2, 2, 1, aesthetasc, 1, 1, 2, 2+aesthetasc, and 7+aesthetasc; most of setae pinnate (as figured). Antenna ( Fig. 24D ) rather stout; coxa short, unarmed; basis broadening distally, with 2 subequal pinnate exopodal setae; first endopodal segment with naked seta on inner margin; compound distal endopodal segment about 3 times longer than wide (118×38 μm), ornamented 2 rows of fine spinules on outer margin and setules on distal half of inner margin; armed with terminal claw plus 9 setae (arranged as 1, 1, 3, 1, and 3 (3 distal setae blunt at tip).

Labrum ( Fig. 24E ) with concave posterior margin bearing scattered rows of setules, dentiform process at each posterolateral corner, and shallow spinulose posteromedianlobe. Mandible ( Fig. 24F ) with 5 teeth (2 distal ones acutely pointed) and 2 setae on coxal gnathobase; basis armed with 1 seta on medial margin and patch of minute spinules on outer margin; exopod 2- segmentedwith 1 and 4 setae onfirst and second segments, respectively, distalmost seta large, about twice as long as adjacent seta; endopod 2-segmentedwith 4 and 10 setae on first and second segments, respectively. Paragnath with angular process medio-distally and setules on medial margin. Maxillule ( Fig. 24G ) with 10 setaeon arthrite, 1 setaon endite, 2 unequal setae on epipodite, ornamented withpatchof minutespinulesnear baseof smaller epipodal seta; basis with 3 setaonmedial margin (proximal one much smaller than distal 2) and row of fine spinules on medial side; exopodwith 4 setae distally; endopod 2- segmented with 1 and 4 pinnate setae on first and second segments, respectively. Maxilla ( Fig. 25B ) 5-segmented; syncoxa with 10 setae grouped as 4, 1, 2, and 3; basis with strong curved clawplus 2 setae; endopod with 1, 1, and 3 setae on first to third segments, respectively. Maxilliped ( Fig. 25C ) 3-segmented and armedwith 10, 1, and 4 setae on first to third segments, respectively; proximal seta on thirdsegment sigmoid, weakly cuticularized.

Legs 1–4 biramous with 3-segmented rami ( Fig. 25 D–F); armature formula as in generic diagnosis. Inner coxal seta large in leg 1 and naked in leg 4. Inner distal spine on basis of leg 1 small, about half as long as first endopodal segment. Outer spines on exopods of legs 2–4 slender but ornamented with membrane distally on both margins.

Leg 5 ( Fig. 25G ) 2-segmented; protopod obscurely defined at base, with 7 spinules on inner margin, and tapering outer distal process (59×24 μm) bearing denticle subdistally on inner margin and weakly pinnate apical seta; free exopodal segment longer than wide (36×30 μm), roundly protruded on outer distal margin, armed with 1 spine and probably 1 seta (missing but scar present), and ornamented with minute spinules on inner margin.

Remarks. Although N. weberi was incompletely characterised by Stock (1950), our single female is identified as N. weberi partly on the basis of shared morphological details such as the presence of 4 and 10 setae on the first and second endopodal segments of the mandible, and the ornamentation of spinules along the inner margin of the protopod of leg 5, but also after consideration of the host. Our female was collected from the type host species and from the type locality and, in addition, the ascidian host Ascidia canaliculata , has never been known to serve as host for any other species of notodelphyid copepod. The presence of 4 setae on the third segment of the maxilliped is a unique feature of N. weberi in the genus Notodelphys , although this feature was not mentioned in the original description ( Stock, 1950).

This species is similar in body form to N. steinitzi and N. parva , but it is markedly larger, with a body length of between 2.94 mm in our female and 4.2 mm in Stock’s type specimen of N. weberi .

Figures

FIGURE 24. Notodelphys weberi Stock, 1950, female. A, habitus, dorsal; B, urosome, ventral; C, antennule; D, antenna; E, labrum; F, mandible; G, maxillule. Scale bars: A, 0.5 mm; B, 0.2 mm; C–G, 0.05 mm.

FIGURE 25. Notodelphys weberi Stock, 1950, female. A, rostum; B, maxilla; C, maxilliped; D, leg 1; E, leg 2; F, leg 4; G, leg 5. Scale bars: 0.05 mm.

FIGURE 58. Notodelphyopsis deplanata sp. nov., female. A, habitus, dorsal; B, urosome, ventral; C, rostrum; D, antennule; E, antenna; F, mandible; G, maxillule. Scale bars: A, 0.2 mm; B-D, F, 0.05 mm; E, G, 0.02 mm.