Paranotodelphys patagonica, 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 : 72-76

Paranotodelphys patagonica sp. nov.

( Figs. 46–48 )

Typematerial. Holotype (intact ♀, MNHN-IU-2014- 21228 ) , paratypes (2 intact ♀♀, MNHN-IU-2014-21229) , and dissected paratypes (1 ♀, 1 ♂, figured) from Ascidia meridionalis Herdman, 1880 (MNHN-IT-2008-1110 = MNHN P5/ ASC.A/4), Calypso expedition 1961–1962, NE Mar del Plata, Argentina (37°36’S, 54°46’W), depth 740 m, B. Métivier coll., 29 December 1961.

Etymology. The name of the new species refers to the type locality.

Descriptionoffemale. Body ( Fig. 46A ) moderately stout and bilaterally compressed. Body length 2.10 mm. Cephalosome with well developed dorsal shield: first to third pedigerous somites each with distinct dorsal tergite. Freeurosome ( Fig. 46B ) cylindrical, 5-segmented: genital somiteshort, 73×262 μm; 4 abdominalsomites 145×200, 153×192, 145×164, and 113×149 μm, respectively. Caudal ramus ( Fig. 46C ) about 5.3 times longerthan wide (239×45 μm) and more than twice as long as anal somite; distal 40% narrower than proximal 60%; ventral surface densely covered by setules: armed with 6 setae, 4 distal setae pinnate; outer lateral seta located at 60% of ramus length; longest terminal seta (seta V) longerthan caudal ramus, but other 5 setae shorter than ramus.

Rostrum ( Fig. 46D ) spatulate, 107×95 μm, slightly longer than wide, with broadly convex distal margin. Antennule ( Fig. 46E ) slender, 9-segmented; armature formula 3, 17, 6, 4+aesthetasc, 4, 2+aesthetasc, 2, 2+aesthetasc, and 7+aesthetasc; second segment partially subdivided into proximal region bearing 5 setae and distal region bearing 12 setae; about half of setae on first to fifth segments pinnate (as figured); distalmost setaon fifth (XVIII-XX) and sixth (XXI-XXIII) segments annulated at base. Antenna ( Fig. 46F ) rather stocky, 4-segmented; coxashortand unarmed; basiswith 2 equally large, pinnate setae representing exopod (setae as long as distal endopodal segment); first endopodal segment with 1 seta on subdistal inner margin; compound distal endopodal segment, 77×29 μm, ornamented with 3 rows of spinules on outer surface; armed with 11 setae (grouped as 1, 1, 3, 2, 1, and 3) plus slender terminal claw, about half as long as segment.

Labrum ( Fig. 46G ) with deeply concave, setulose posteriormargin. Mandible ( Fig. 46H ) with 5 teethand 2 small setae on coxal gnathobase; distalmost tooth acutely pointed and proximalmost tooth bifurcate; basis with 1 subdistal seta on medial margin; exopod with 5 setae, 2 distalsetae longerthan other 3; endopod 2-segmented and armed with 2 and 9 setae on first and second segments, respectively. Paragnath ( Fig. 46I ) with blunt lobe at outer distal corner and ornamented with dense setules onmedial margin. Maxillulewith 9 setaeon arthrite, 1 on coxal endite, 2 on coxal epipodite; basis with 1 small proximal and 2 longer distal setae on medial margin; exopod with 4 setae distally; endopod incompletely 2- segmented, with 2 setae on first segment and 4 subequally long setae on second segment. Maxilla ( Fig. 47A ) 5- segmented; syncoxawith 10 setae (4, 1, 2, and 3), basis with 2 setae plus slender claw, 1, 1, and 3 setae on first to third endopodal segments, respectively. Maxilliped ( Fig. 47B ) 3-segmented, with 9, 0, and 3 setae on first to third segments respectively; second segment ornamented with setules on medial margin, patch of spinules distally, but lacking outer distal bulbous swelling.

Legs 1–4 with 3-segmented rami ( Fig. 47 C–E). Inner coxal seta pinnate in legs 1–3, naked in leg 4. Outer seta on basis inall swimming legs smalland naked. Inner distal spine on leg 1 basis 83 μm long, extending to posterior margin of second endopodal segment, spinulose on both margins; 2 inner subdistal setae on third endopodal segment of leg 1 enlarged. Armature formula for legs 1–4 as in generic diagnosis.

Leg 5 ( Fig. 47F ) represented by protopod and small free exopod; protopod fused to brood pouch, bearing outer distal process tipped with 1 naked seta; exopodal segment widerthan long, strongly tapering, 21×26 μm, with 1 naked seta apically.

Description of male. Body ( Fig. 48A ) curved ventrally. Bodylength 1.43 mm. Urosome ( Fig. 48B ) 6- segmented: comprising free fifth pedigerous somite 177 μm wide, short genital somite, 73×173 μm, ornamented with transverse row of fine spinules on ventral surface of genital operculum ( Fig. 48E ), and four abdominal somites 105×139, 114×127, 109×115, and 75×91 μm, respectively. First abdominal somite ornamented with 3 transverse rows of fine spinules on ventral surface. Anal somite distinctly narrower than third abdominal somite. Caudal ramus about 4.4 times longer than wide (120×27 μm); outer lateral seta located at midlength of ramus.

Rostrum as in female. Antennule ( Fig. 48C ) 10- segmented; armatureformula 3, 17, 2, 2, 2, 4+aesthetasc, 1, 3, 2+aesthetasc, and 11+aesthetasc; secondsegment subdivided by partial suture lines; segmental fusion pattern I-II, III-XI, XII, XIII, XIV, XV-XVI, XVII, XVIII-XX, XXI-XXIII, XXIV-XXVIII. Antenna as in female.

Labrum, mandible, paragnath, maxillule, and maxilla asin female. Maxilliped ( Fig. 48D ) armedwith 7 (3+4) setae on first segment; second segment ornamented with patch of spinules distally, as in female.

Legs 1–4 with samearmatureformulaasin female, but 2 inner subdistal setae on third endopodal segment of leg 1 not enlarged. Leg 5 ( Fig. 48E ) similartothatof female, but outer distal process of protopod less prominent; free exopodal segment 20×22 μm. Leg 6 ( Fig. 48E ) represented by 2 equal, naked setae on genital operculum.

Remarks. Several species of Paranotodelphys are known to have hirsute caudal rami that are densely ornamented with fine setules on the ventral or inner surfaces. These species are P. procax , P. villosus , P. stenosa sp. nov., and P. bidentata sp. nov. and each can be readily differentiated from the new species. The new species has 3 setae on the distal segment of the maxilliped whereasthereare only 2 setaein P. procax . Both P. villosus and P. stenosa sp. nov. have elongated caudal rami (more than 10 times longer than wide in the former and about 9.2 times longer in the latter), whereas the new species has caudal rami that are only about 5.3 times longer than wide, The long, thread-like caudal setae and the broad rostrum of P. bidentata sp. nov. serve to differentiate it from the new species which has short caudal setae and narrow pointed rostrum.

The patch of spinules located distally on the second segment of the maxilliped, the presence of 9 setae on the second endopodal segment of the mandible, and the presence of a distinct (although small) free exopodal segment of leg 5 are all unique characteristics within the genus, serving as diagnostic features of the new species.

Figures

FIGURE 46. Paranotodelphys patagonica sp. nov., female. A, habitus, right; B, urosome, ventral; C, left caudal ramus, ventral; D, rostrum; E, antennule; F, antenna; G, labrum; H, mandible; I, paragnath; J, maxillule. Scale bars: A, 0.2 mm; B, 0.1 mm; C–H, 0.05 mm; I, J, 0.02 mm.

FIGURE 47. Paranotodelphys patagonica sp. nov., female. A, maxilla; B, maxilliped; C, leg 1; D, leg 2; E, leg 4; F, leg 5. Scale bars: A, B, F, 0.02 mm; C–E, 0.05 mm.

FIGURE 48. Paranotodelphys patagonica sp. nov., male. A, habitus, right; B, urosome, ventral; C, antennule; D, maxilliped; E, legs 5 and 6. Scale bars: 0.2 mm; B, 0.1 mm; C, E, 0.05 mm; D, 0.02 mm.