Notodelphyopsisfalcifera 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 : 80

Notodelphyopsisfalcifera Schellenberg, 1922

( Figs. 51 , 52 )

Material examined. 1 ♀ (dissected and figured) from Ascidia depressiuscula Heller, 1878 , Gulf of Manaar India.

Supplementary description of female. Body ( Fig. 51A, B ) narrow, dorsoventrally depressed and arched ventrally. Bodylength 2.43 mm. Cephalosome with angular posterolateral corners and concave posterior margin; widerthan first 3 pedigerous somites. First to third pedigerous somites broader posteriorly. Brood pouch elongatedoval, 930×590 μm, longer than preceding part of prosome, and widest in middle; fifth pedigerous somite completely fused with brood pouch. Free urosome ( Fig. 51C ) consisting of genital double-somite and 3- segmented abdomen: genital double-somite 114×175 μm; freeabdominalsomites 80×134, 91×127, and 80×118 μm, respectively. Caudalramus ( Fig. 51C ) elongate, about 12 timeslongerthan wide (500×41 μm), gradually narrowing distally; armed with 6 small setae, all setae shorter than width of ramus; proximal outer lateral seta located at 30% of ramus length.

	Coxa	Basis	Exopod	Endopod
Leg 1	0-1	1-I	I-0; I-1; III, 1, 4	0-1; 0-1; 1, 2, 3
Leg 2	0-0	1-0	I-0: I-1; III, I, 5	0-1; 0-2; 1, 2, 3
Leg 3	0-1	1-0	I-0: I-1; III, I, 5	0-1; 0-2; 1, 2, 3
Leg 4	0-1	1-0	I-0; I-1; III, I, 5	0-1; 0-2; 1, 2, 2

Rostrum( Fig.51D )clearlydefinedfromcephalosome, spatulate, broadened in distal third, 78×86 μm. Antennule long and slender, 7-segmented, reaching to posterior margin of third pedigeroussomite when extended; seventh segment subdivided distally by indistinct suture line; armatureformula 3, 17, 6, 4, 4, 2, and 11+aesthetasc; all setae small and naked. Antenna ( Fig. 51F ) 3-segmented: coxa short and unarmed; allobasis slightly inflated in middle with 2 unequal, pinnate setae representing exopod on outer margin; longer seta as long as free endopodal segment, shorter seta about half as long; free endopodal segment slightly shorter and narrower than basis, 82×19 μm, armed with 8 setae plus terminal claw more than half length of segment.

Labrum hirsute distally, with straight posterior margin and small posteromedian lobe. Mandible ( Fig. 51G ) with 5 teeth and 2 small setae on coxal gnathobase, 2 small spinules on distal margin near base of distalmost tooth; basis with 1 seta on medial margin and scattered setules on ventral surface; exopod unsegmented with 5 setae, distal 2 setae distinctly larger (about twice length of other 3); endopod with 2 and 8 setae on first and second segments, respectively. Paragnath ( Fig. 52A ) as small lobe bearing rounded protuberance at outer distal corner and dense setules on medial surface. Maxillule ( Fig. 51H ) with 9 setae on arthrite, 1 on coxal endite, 2 on coxal epipodite, and 1 small proximal and 2 longer distalsetae onmedial margin of basis; exopod with 4 setae distally; endopod 2-segmented with 2 setae on first segment and 3 setaeon second. Maxilla ( Fig. 52B ) 5-segmented; with 9 enditic setae on syncoxa (arranged as 3, 1, 2, 3), 3 on basis, and 1, 1, and 3 on first to third endopodal segments. Maxilliped ( Fig. 51I ) 3-segmented, armedwith 9, 0, and 2 setae on first to third segments, respectively; articulation incomplete between second and third segments.

Legs 1–4 with 3-segmented rami. All legs lacking inner seta on first exopodal segment. Inner coxal seta large inleg 1 ( Fig. 52C ), absentin leg 2 ( Fig. 52D ), and small in legs 3 and 4 ( Fig. 52E ). Outer seta on basis large and pinnate in leg 1, but small and naked in legs 2–4. Inner distal spine on basis of leg 1 longer than first endopodal segment, 65 μm long. Exopod of leg 1 strongly curved, first segment broadened distally. Outer spines on first and second exopodal segments of legs 2–4 strong, curved outwards, claw-like. Inner setaeon exopods and endopods of legs 2–4 short and naked. Third exopodal segment of leg 4 characteristically armed with 4 spines and 5 setae as in legs 2 and 3. Armature formula for legs 1–4 as follows:

Leg 5 ( Fig. 52F ) represented by 2 small papillae, each tipped with 1 small seta.

Male. Not found.

Remarks. The presence of nine setal elements (III, I, 5) on the third exopodal segment of leg 4 is very unusual for notodelphyids. Even the two new basal genera Bathynotodelphys gen. nov. and Pronotodelphys gen. nov. erected in the present account (above) possess a maximum of eight elements (II, I, 5) on this segment, and this maximum is shared with Notodelphys and Paranotodelphys . The absence of an inner coxal seta on leg 2 only is also extremely unusual in copepods. When setae are lost along a leg series, the loss tends to follow an anterior to posterior, or a posterior to anterior sequence. The absence of this seta in leg 2 while it is present in legs 1, 3 and 4 requires confirmation.

The known hosts of this Indo-Pacific species include thetype host, Ascidia gemmata Sluiter, 1895 in Australia ( Schellenberg, 1922), A. zara Oka, 1935 and Ciona intestinalis in Japan ( Ooishi, 1962), and Phallusia nigra Savigny, 1816 in Korea ( Kim, 2012). Here we add Ascidia depressiuscula from India as a new host record.

Figures

FIGURE 51. Notodelphyopsis falcifera Schellenberg, 1922, female. A, habitus, dorsal; B, habitus, right; C, urosome, ventral; D, rostrum; E, antennule; F, antenna; G, mandible; H, maxillule; I maxilliped. Scale bars: A, B, 0.2 mm; C, 0.1 mm; D–G, 0.05 mm; H, I, 0.02 mm.

FIGURE 52. Notodelphyopsis falcifera Schellenberg, 1922, female.A, paragnath; B, maxilla; C, leg 1; D, leg 2; E, leg 4; F, leg 5. Scale bars: A, B, 0.02 mm; C–E, 0.05 mm; F, 0.01 mm.