Paranotodelphys bidentata, 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 : 61-64

Paranotodelphys bidentata sp. nov.

( Figs. 40 , 41 )

Type material. Holotype ♀ (dissected and mounted on a slide, MNHN-IU-2014-21224 ) from Pseudodistoma aureum (Brewin, 1957) (MNHN-IT-2008-7326 = MNHNA1/PSE/67), Baluan, Papua New Guinea (02°02.27 Ś, 147°17.97 É), CRRFOCDN 8852-H, 22 June 2003.

Additionalmaterial. 1♀ (dissected)from Rhopalaea crassa (Herdman, 1880) , Papua New Guinea (09°07.50 Ś, 149°23.54 É), depth 7 m, 22 January 2002.

Etymology. The name of the new species refers to the presence of a pair of tooth-like processes on the apex of the rostrum.

Descriptionoffemale. Body ( Fig. 40A, B ) narrow, 1.50 mm long. Cephalosome wider than freepedigerous somites. Dorsal tergites of second and third pedigerous somite weakly developed. Brood pouch elongated oval, 591×302 μm, about twice as long as wide, slightly longer than anterior part of prosome: fifth pedigerous somite completely fused tobrood pouch. Free urosome ( Fig. 40C ) slender, 5-segmented; 35×88, 57×65, 50×56, 47×56, and 57×64 μm, respectively.Anal somitegraduallybroadening posteriorly. Caudalramus ( Fig. 40C ) about 5.9 times longer than wide (135×23 μm) and about 2.4 times longer than anal somite, setulose on ventral surface, bearing 6 thin, thread-like setae, longest one (seta V) more than 3 times longer than caudal ramus; outer lateral seta located about at midlength of ramus.

Rostrum ( Fig. 40D ) nearly semicircular, 54×62 μm, bidentate at apex. Antennule ( Fig. 40E ) 9-segmented; armatureformula 3, 18, 6, 3+aesthetasc, 4, 2+aesthetasc, 2, 2+aesthetasc, and 7+aesthetasc; all setae naked except 2 pinnatesetaeonthirdsegment. Antenna ( Fig. 40F ) 4- segmented; shortcoxa unarmed; basiswith2 equal, pinnate setae representing exopod; first endopodal segment with 1 naked seta on inner margin; compound distal endopodal segment about 2.8 times as long as wide (45×16 μm), slightly broadening distally, with 11 setae plus short terminal claw, less than half length of segment.

Labrum ( Fig. 41A ) densely hirsute around posterior margin; with small posteromedian lobe located on ventral surface. Mandible ( Fig. 40G ) with 5 teeth on coxal gnathobase, distalmost tooth acutely pointed, and with needle-like spinulebetween proximal 2 teeth; basis with 1 seta on distal medial margin, stout proximal tubercle on outer margin, and ornamented with setules on both margins; exopod 2-segmented, with 2 and 3 setaeon first and second segments, respectively, outer terminal seta large, more than twice as long as second longest adjacent seta; endopod almost fused with basis, with 2 and 8 setae on first and second segments, respectively. Maxillule ( Fig. 40H ) with 7 setae on arthrite, 1 on coxal endite, 2 on coxal epipodite, and 3 on medial margin of basis, proximal 2 setae much smaller than distal seta; exopod with 4 distal setae; endopod unsegmented with 3 large distal and 3 smaller lateral setae. Maxilla ( Fig. 41B ) 5-segmented with 9 enditic setae on syncoxa (arranged as 3, 1, 2, and 3), 3 on basis, and 1, 1, and 3 on first to third endopodal segments, respectively. Maxilliped ( Fig. 41C ) 3-segmented with 9, 0, and 3 setae on first to third segments; second segment with outer bulbous swelling and setulose along medial margin; articulation obscure between distal 2 segments.

Legs 1–4 with 3-segmented rami. Leg 1 ( Fig. 41D ) with patch of minute spinules on anterior surface of coxa; exopod strongly flexed laterally; distal spine on third exopodal segment densely plumose on all margins; third endopodal segment expanded, with enlarged distal setae. Inner seta on coxa large and pinnate in leg 1, naked in leg 2, small and naked in leg 3, and absent in leg 4. Outer seta on basis pinnate in leg 1 but naked in legs 2–4. Inner distal spine on basis of leg 1 as long as first endopodal segment, 37 μm long, ornamented with fine spinules on margins. Spines on first and second exopodal segments of legs 2–4 strong, claw-like and curved outwards; those on second exopodal segment of legs 2 and 3 large, extending beyond distal margin of third exopodal segment. Outer spine on third exopodal segment of legs 2–4 pectinate distally on outer margin. Armature of legs 1–4 as usual for genus, except inner seta on coxa of leg 4 absent.

Leg 5 ( Fig. 40C ) represented by 2 small papillae each tipped withsmall seta.

Male. Unknown.

Remarks. The following outstanding features serve to characterise the new species: (1) the caudal setae are long and thread-like; (2) the distalmost spine on the third exopodal segment of leg 1 is densely plumose; (3) the third endopodal segment of leg 1 is expanded and has enlarged distal setae; and (4) the outer spines on the first and second exopodal segments of legs 2–4 are large and claw-like. These characteristics seem to be unique to the new species within the genus.

Figures

FIGURE 40. Paranotodelphys bidentata sp. nov., female. A, habitus, dorsal; B, habitus, right; C, urosome and caudal rami, ventral; D, rostrum; E, antennule; F, antenna; G, mandible; H, maxillule. Scale bars: A, B, 0.2 mm; C, 0.05 mm; D–H, 0.02 mm.

FIGURE 41. Paranotodelphys bidentata sp. nov., female. A, labrum; B, maxilla; C, maxilliped; D, leg 1; E, leg 2; F, leg 4. Scale bars: 0.02 mm.