Paranotodelphys molgulae, 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 : 76-79

Paranotodelphys molgulae sp. nov.

( Figs. 49 , 50 )

Type material. Holotype ♀ (dissected and mounted on a slide, MNHN-IU-2014-21230 ) from Molgula pyriformis Herdman, 1881 (MNHN-IT-2008-5729 = MNHNS3/ MOL.A/149), Cruise 721 of HERO, Tierra del Fuego, Argentina (54°34’S, 064°10’W), depth 73 m, January 1952.

Etymology. The new species takes its name from the generic name of the type host.

Descriptionoffemale. Body ( Fig. 49A ) stocky, similar in form to Doropygus species. Body length 3.29 mm. Second and third pedigerous somites each with well developed dorsal tergite. Brood pouch sub-globular and incorporating fifth pedigerous somite. Free urosome ( Fig. 49B )5-segmented:genitalsomiteand 4 abdominalsomites 200×406. 224×352, 230×321, 188×267, and 170×261 μm, respectively.Anal somite gradually narrowing posteriorly. Caudal rami divergent and slender; each ramus ( Fig. 49C ) graduallynarrowing distally, about 5.4 times longerthan wide (295×55 μm); armed with 6 setae, all setae naked and much shorter than ramus; outer lateral seta (seta II) located at 28% of ramus length; subdistal seta (seta VII) located at 83% of ramus length.

Rostrum ( Fig. 49D ) evenly tapering, about 1.4 times longerthan wide (164×115 μm), well defined basally, and with pointed apex. Antennule ( Fig. 49E ) distinctly narrowing distally and 10-segmented; proximal 2 segments much broader than distal segments; armature formula 3, 16, 6, 4+aesthetasc, 1, 3, 2+aesthetasc, 1, 2+aesthetasc, and 7+aesthetasc; 2 setae on first segment and 4 setae on second segment pinnate and much larger than other setae (as figured). Antenna ( Fig. 49F ) 3- segmented; coxa short and unarmed; allobasis with 2 equally long, weakly pinnate setae (both setae as long as freeendopodal segment) representing exopod and 1 small seta on inner margin derived from incorporated first endopodal segment; free endopod 1-segmented, about 4.4 times as long as wide (61×14 μm); armed with terminal clawplus 11 smallsetae (arranged as 1, 1, 3, 1, 2, and 3), all setae attenuated at tip, terminal claw about twice as long as segment.

Labrum ( Fig. 49G ) with setulose posterior margin and broad posteromedian lobe ornamented with setules and spinules. Mandible ( Fig. 49H ) with 5 teethand 2 small setae on coxal gnathobase, proximal tooth minutely bifurcate; basiswith 1 setaonmedial margin; exopod 2-segmented with 2 and 3 setae on first and second segments, respectively, all 5 setae about equal in length; endopod with 4 and 10 setae on first and second segments, respectively. Paragnath ( Fig. 49I ) with dense setules on medial surface, lacking denticle or lobe. Maxillule ( Fig. 50A ) with 9 setaeon arthrite; coxa indistinctly defined, with 1 setaon endite and 2 unequal setae on epipodite, smaller distal seta ( Fig. 50B ) characteristically constricted in middle; basiswith 3 setae (2 smallproximal and 1 long distal) onmedial margin; exopodwith 4 setae distally; endopod indistinctly 2-segmented with 2 setae medially on first segment and 4 setae on second segment. Maxilla ( Fig. 50C ) 5-segmented; syncoxawith 4 (including minute seta), 1, 2, and 3 setae on first to fourth endites, respectively; basis with claw bearing spinules along concave margin, plus 2 setae; endopodwith 1, 1, and 3 setae on first to third segments, respectively. Maxilliped ( Fig. 50D ) incompletely 3-segmentedwith 9, 0, and 2 setae on first to third segments, respectively; 2 distal segments small; second segment ornamented with dense setules on all surfaces.

Legs 1–4 with 3-segmented rami ( Fig. 50 E–G). Inner seta on coxa of all swimming legs pinnate and distinct. Outer seta on basis of all legs small and naked. Inner distal spine on basis of leg 1 finely spinulose, 75 μm long, as long as first endopodal segment. Exopod of legs 2–4 bearing setiform elements (not spines) on outer margin. Inner seta on first exopodal segment of leg 4 small. Armature formula for legs 1–4 as follows:

Coxa Basis Exopod Endopod
Leg 1	0-1	1-I	I-1; I-1; III, I, 40-1; 0-1; 1, 2, 3
Legs 2 & 30-1		1-0	1-1: 1-1; 3, 2, 40-1; 0-2; 1, 2, 3
Leg 4	0-1	1-0	1-1; 1-1; 2, 2, 40-1; 0-2; 1, 2, 2

Leg 5 ( Fig. 49H ) represented by 2 lobes (small outer and larger inner), each tipped with 1 naked seta.

Male. Unknown.

Remarks. Three species of Paranotodelphys are known to have an allobasis plus a 1-segmented free endopod in the antenna as in the new species ( P. furcifera , P. saccata , and P. polycarpae sp. nov.). However, these three congeners can be readily differentiated from the new species because all have 3 setae on the third maxillipedal segment in contrast to only 2 in the new species. All described species of Paranotodelphys have 2 or 3, and 7 to 9 setae on the first and second endopodal segments of the mandible, respectively, except P. longicaudata in which the setation of the mandibularendopod isunknown. Therefore, the possession of 4 and 10 setae, respectively, on these segments in the new species is a unique armature configuration within Paranotodelphys . As an additional diagnostic feature, the new species has setiform elements rather than spines, on the outer margin of the exopod of legs 2–4.

Figures

FIGURE 49. Paranotodelphys molgulae 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. Scale bars: A, 0.5 mm; B, 0.2 mm; C, E, H, 0.1 mm; D, G, I, 0.05 mm; F, 0.02 mm.

FIGURE 50. Paranotodelphys molgulae sp. nov., female. A, maxillule; B, distal seta of coxal epipodite of maxillule; C, maxilla; D, maxilliped; E, leg 1; F, leg 2; G, leg 4. Scale bars: A, C, D, 0.05 mm; B, 0.01 mm; E–G, 0.1 mm; H, 0.02 mm.