Pygodelphys novaeseelandiae ( Schellenberg, 1922 )

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 : 96

Pygodelphys novaeseelandiae ( Schellenberg, 1922) ( Figs. 62 , 63 )

Material examined. 1 ♀ (dissected and figured) from Polycarpa sp., Antipodes Island, New Zealand, Eltanin 27, Stn 1850 (49°40’S 178°53’E), depth 476-540 m, 1967.

Supplementary description of female. Body ( Fig. 62A ) strongly flexed ventrally with brood pouch greatly expanded lengthwise, extending beyond tips of caudal rami. Body length 3.45 mm measured from anterior margin of cephalosome to distal end of caudal rami. Prosome longer than body length, 3.94 mmlong measured from anterior margin of cephalosome to posterior end of brood pouch. Freeurosome ( Fig. 62B ) 5-segmented and graduallynarrowing posteriorly; Comprising short genital somite and 4 free abdominal somites. Genital and first abdominal somites each ornamented with rows of minute spinules on ventral surface. Caudal ramus ( Fig. 62C ) slightly curved, about 6.2 times longerthan wide (409×66 μm) and twice as long as anal somite, slightly narrowing distally; armed with 6 naked setae, outer lateral setae located at 39% of ramus length.

Rostrum ( Fig. 62D ) broad in proximal third, strongly tapering towards apex in distal two-thirds. Antennule ( Fig. 62E ) 9-segmented; armatureformula 3, 16, 6, 4, 4, 2+aesthetasc, 1, 2+aesthetasc, and 7+aesthetasc; setae crowded, most large and naked; 2 pinnate setaeon first and 1 on second segments. Antenna ( Fig. 62F ) 3-segmented; coxa short and unarmed; allobasis with 2 equally long, slender setae (1 unilaterally weakly pinnate and 1 naked) on outer margin representing exopod, and 1 seta derived from first endopodal segment; compound distal endopodal segment about twice as long wide (106×50 μm), shorter than allobasis, armed with 11 setae (all attenuated at tip) plus strong terminal claw.

Labrum ( Fig. 62G ) with setulose, roundly produced posterolateral corners and several spinules on midposterior border. Mandible ( Fig. 62H ) with 6 teethand 2 small setae on coxal gnathobase and 1 small spinule between proximal second and third teeth; basis with 1 seta and setules on medial margin; exopod unsegmented with 5 equally long setae; firstendopodal segment with 4 setae on medial margin and row of minute spinules on posterior border; secondsegment with 10 setae. Maxillule ( Fig. 62I ) armed asin P. antarctica . Maxilla ( Fig. 63A ) 5-segmented; syncoxawith 9 enditic setae, arranged as 3, 1, 2, and 3; basis with strong claw plus 2 setae; endopod small, armedwith 1, 1, and 3 setaeonfirst to third segments, respectively; one setaon third segment naked, other setae on endopod pinnate with long setules. Maxilliped ( Fig. 63B ) 2-segmentedwith 9 setaeonfirst segment and 2 on second; second segment subdivided by trace of articulation distally.

Legs 1–4 with 3-segmented rami ( Figs. 63 C–E). Inner distal spine on basis of leg 1 slightly longer than first endopodal segment. Exopods of legs 2–4 bearing only setae; outer setae on exopods elongate and usually naked. Armature formula for legs 1–4 as in P. antarctica .

Leg 5 ( Fig. 63F ) represented by 2 lobes each tipped with 1 naked seta; inner (exopodal) lobe bearingadditional dentiform process on subdistal inner margin.

Male. Not found.

Remarks. Jones (1974) re-examined the type specimens of this species and provided a redescription based on newly collected material. Five species of solitary ascidians are known as hosts of P. novaeseelandiae in New Zealand waters and Jones (1974) collected more than 300 specimens, all females, and recorded their mean bodylength as 1.5 mm ± 0.4, contrasting markedly with the 3.45 mm length of our specimen. In contrast to our specimen, Jones (1974) illustrated an ovigerous female with a brood pouch that was not markedly expanded and was shorter than the urosome. However, in the original description, Schellenberg (1922) reported that the brood pouch was longer than the anterior part of the prosome. Thus, it seems likely that the specimens collected by Jones in New Zealand waters might not have been fully grown adults. The small dentiform process on the inner margin on the exopodal lobe of leg 5, which is characteristic of this species, was figured by Jones.

Figures

FIGURE 62. Pygodelphys novaeseelandiae (Schellenberg, 1922), female. A, habitus, right; B, urosome, ventral; C, caudal ramus, medial; D, rostrum; E, antennule; F, antenna; G, labrum; H, mandible; I, maxillule. Scale bars: A, 0.5 mm; B, C, 0.1 mm; D–I, 0.05 mm.

FIGURE 63. Pygodelphys novaeseelandiae (Schellenberg, 1922), female. A, maxilla; B, maxilliped; C, leg 1; D, leg 2; E, leg 4; F, leg 5. Scale bars: A–E, 0.1 mm; F, 0.05 mm.