Paranotodelphys tuberculata, 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 : 69-72

Paranotodelphys tuberculata sp. nov.

( Figs. 44 , 45 )

Typematerial. Holotype (intact ♀, MNHN-IU-2014- 21226 ) , paratype (intact ♀, MNHN-IU-2014-21227) , anddissectedparatype (♀, figured) from Ecteinascidia aequale Monniot C., 1987 (MNHN-IT-2008-3815 = MNHN P2/ ECT /43), Îlot Maître, New Caledonia, Monniot coll., 1985.

Etymology. The name of the new species refers to the presence of a tubercle located proximally on the outer margin of the mandibular basis.

Description of female. Body ( Fig. 44A ) similar in form to preceding species ( P. bisetata sp. nov.). Body length 1.29 mm. Posterolateral corners of cephalosome extended posteriorly ( Fig. 44B ). First pedigerous somite slightly narrower than second and third pedigerous somites. Brood pouch oval in dorsal view, but circular in lateral view ( Fig. 44A ). Freeurosome ( Fig. 44C ) slender, 5-segmented; genital and 4 free abdominal somites graduallynarrowingposteriorly 82×175, 68×125, 61×111, 59×102, and 84×97 μm, respectively. Caudalramus ( Fig. 44D ) about 5.9 times as long as wide (205×35 μm), smooth; armed with 6 setae, outer lateral seta positioned at 33% of ramus length.

Rostrum ( Fig. 44E ) tapering strongly, 82×59 μm, articulated at base from cephalosome, with blunt apex. Antennule ( Fig. 44F ) slender, 9-segmented; first and second segments slightly broadened; armature formula 3, 17, 6, 4+aesthetasc, 4+aesthetasc, 2+aesthetasc, 2, 2+aesthetasc, and 7+aesthetasc; several setae on first and second segments pinnate (as figured); suture line between first 2 segments obscure. Antenna ( Fig. 44G ) 4-segmented; coxa unarmed; basis with several minute spinules on outer margin and armed with 2 unequal setae representing exopod, long pinnate seta and naked seta, half length of pinnate seta; first endopodal segment with 1 seta on inner side; compound distal endopodal segment about 3 times as long as wide; armed with 9 setae plus slender terminal claw, less than half as long as segment.

Labrum ( Fig. 44H ) simple, with setule rows along posteriormargin. Mandible ( Fig. 44I ) with 5 teethand 2 smallproximalsetaeoncoxal gnathobase, distalmost tooth acutely pointed; needle-like spinule present between 2 proximal teeth; basis with prominent proximal tubercle on outer margin (arrowhead in Fig. 44I ), armed with 1 seta on subdistal medial margin and ornamented with setules on medial margin; exopod with 5 unequal setae, outer distal seta much larger than others; endopod 2-segmented with 2 and 8 setae on first and second segments, respectively; outer distal seta on second endopodal segment slightly swollen at base. Maxillule ( Fig. 44J ) with 8 setae on arthrite, 1 on coxal endite, 2 on coxal epipodite; basis with 3 setae (2 smallproximal and 1 larger distal) onmedial margin; exopod with 4 setae distally; endopod distinctly 2-segmented with 2 small setae on medial margin of first segment and 4 setae on second segment, outermost seta much smaller than other 3; all setae on maxillule pinnate. Maxilla ( Fig. 45A ) 5-segmented; armedwith 9 setaeon 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. 45B ) 3-segmented, with 9, 0, and 3 setae on first to third segments, respectively; first segment ornamented with minute spinules on all surfaces; second segment with setules on medial margin and produced into bulbous swelling at outer distal corner.

Legs 1–4 with 3-segmented rami ( Fig. 45 C–E). Inner seta on coxa becoming shorter from legs 1 to 4, pinnate in legs 1–3, and naked 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 much longer than first endopodal segment, 62 μm long, and spinulose on margins. Distal spine and setae on third exopodal segment of leg 1 and outer spines on exopod of legs 2–4 pectinate along outer margin. Spines on third exopodal segment of leg 2 broadened. Inner seta on first exopodal segment of leg 4 small but pinnate; all other setae on leg 4 naked. Armature formula for legs 1–4 as in generic diagnosis.

Leg 5 ( Fig. 44C ) represented by 2 papillae on posterior border of brood pouch, each tipped with 1 tiny seta.

Male. Unknown.

Remarks. In the genus Paranotodelphys the exopod of the antenna is represented by a pair of setae and in most known species these setae are equal or subequal in length. However, in a few species these two setae differ markedly in size, the shorter one being at most half the length of the other, as in the new species. The new species shares this feature with P. procax and P. nodulosa sp. nov. but differs from them as follows: P. procax has densely hirsute caudal rami, only 2 setae (3 setae in the new species) on the third segment of the maxilliped, and an unsegmented maxillulary endopod. In the new species the caudal rami are smooth and the maxillulary endopod is distinctly 2-segmented. In P. nodulosa sp. nov. the female has a strongly tapering rostrum, both exopodal setae of the antenna are pinnate (cf. the smaller one is naked in the new species), and the coxa of leg 4 lacks an inner seta (seta present in the new species).

The precise format of the exopodal setae on the antenna is unknown in P. gracilis and P. longicauda , both described by Schellenberg (1922), but these species are distinguishable from the new species by other characters. Paranotodelphys gracilis has a larger body (2.2–2.5 mm, according to Schellenberg, 1922), a “2-segmented maxilliped” and longer abdominal somites which are as wide as long, whereas P. longicauda has an elliptical brood pouch and caudal rami which are 3 times as long as the anal somite (cf. about 2.4 times longer in the new species). These differences are sufficient to justify the establishment of a new species.

Figures

FIGURE 44. Paranotodelphys tuberculata sp. nov., female. A, habitus, left; B, anterior part of prosome, dorsal; C, urosome, ventral; D, right caudal ramus, dorsal; E, antennule; G, antenna; H, labrum; I, mandible showing outer tubercle on basis (arrowhead); J, maxillule. Scale bars: A–C, 0.1 mm; D, F, H, I, 0.05 mm; E, G, J, 0.02 mm.

FIGURE 45. Paranotodelphys tuberculata sp. nov., female. A, maxilla; B, maxilliped; C, leg 1; D, leg 2; E, leg 4. Scale bars: 0.05 mm.