Doropygus caribbensis, 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 : 329-332

Doropygus caribbensis sp. nov.

( Figs. 218 , 219 )

Type material. Holotype ♀ (dissected and mounted on a slide, MNHN-IU-2014-21310 ) from Polycarpa multiplicata Monniot C., 1983 (MNHN-IT-2008-6569 = MNHNS1 POL.B 162), St. François, Guadeloupe 83-15, diving, Monniot coll., 30 March 1983.

Etymology. The new species is named after its geographical origin, the Caribbean.

Descriptionoffemale. Body ( Fig. 218A ) clearly segmented; length 2.81 mm. Body with thick rigid exoskeleton, asin D. reticulatus sp. nov., butdorsalsurface of cephalosome and first to third pedigerous somites smooth, without reticulation. Dorsalcephalic shield and second and third pedigerous somites ornamented with surface granulation along lateral and posterodorsal margins. Fourth pedigerous somite greatly expanded, forming brood pouch, dorsal surface reticulated with hexagonal sculptures ( Fig. 218B ; indicated by arrowhead in Fig. 218A ); about twice as long as anterior part of prosome, 1.3 times longerthanwide inlateral view, with straight ventral margin and rounded dorsal and posterior margins. Freeurosome ( Fig. 218C ) 5-segmented: genital somite rectangular, 181×259 μm; first to third abdominal somites strongly sclerotized, each broadening posteriorly, 182×218, 171×215, and 135×182 μm, respectively. Anal somite quadrate, 145×149 μm. Caudalramus ( Fig. 218D ) slender, curved ventrally, 6.0 times longerthan wide (300×50 μm) and 2.1 times longer than anal somite; armed with 6 small, thin setae; 2 proximal setae located at 32 and 71% of ramus length; all setae shorter than ramus width.

Rostrum as blunt, broad apical process on cephalosome ( Fig. 218A ). Antennule ( Fig. 218E ) 313 μm long, 9-segmented; first and second segments distinctly broader than remaining segments; armature formula 3, 17, 6, 4+aesthetasc, 4, 3+aesthetasc, 2, 2+aesthetasc, and 7+aesthetasc; setae crowded, many pinnate.Antenna ( Fig. 218F ) 4-segmented; coxa unarmed; basis 97×51 μm, with 1 small seta distally; first endopodal segment 75×56 μm, with 1 smallseta subdistally; compounddistalendopodal segment slender, 4.0 timeslongerthan wide (132×33 μm); armed with 8 setae (including 1 subdistal pinnate and 3 distal, bluntly tipped setae) plus small terminal claw, onethirdaslongas segment.

Labrum ( Fig. 218G ) tapering from broad base to narrow posterior margin, ornamented with minutesetules on both sides; posteromedian lobe small and smooth. Mandible ( Fig.218H ) with 5 teeth, 1 distalsubsidiarytooth and 2 smallproximal setaeon coxal gnathobase; basis with 1 seta mediodistally; exopod slender, with 5 setae, third and fourth setae slightly longer than other 3; first endopodal segment armed with 4 setae and ornamented with spinules at inner and outer distal corners; second endopodal segment with 10 setae and ornamented with spinules on distal outer margin; 2 distal setae on second segment distinctly larger than other 8. Maxillule ( Fig. 218I ) and maxilla ( Fig. 219A ) armed as in D. reticulatus sp. nov., but seta on coxal endite of maxillule broader. Maxilliped ( Fig. 219B ) incompletely 2-segmented; first segment with 9 setae and proximal patch of setules; second segment small with 2 apical setae and setules on medial margin.

Leg 1 ( Fig. 219C ) with 3-segmented rami. Inner coxal seta elongate, extending about to tip of inner spine on basis. Outer seta on basis lanceolate: inner distal spine on basis 76 μm long, spinulose along distal half, and extending to middle of third endopodal segment. Outer spine on first exopodal segment large, twice as long as spine on second segment.

Legs 2–4 with 3-segmented exopods and 2- segmented endopods ( Fig. 219D, E ); both rami slender; endopods longer than exopods. Inner coxal seta of legs 2 and 3 pinnate, extending about to distal margin of endopod; that of leg 4 naked and extending to middle of secondendopodal segment. Outer setaon basis of legs 2–4 small. Second endopodal segment of leg 4 slightly shorter than entire exopod. First exopodal segment of leg 4 lacking inner seta. Armature formula for legs 1–4 as in D. reticulatus sp. nov.

Leg 5 ( Fig. 219F ) 2-segmented: protopod with 1 seta at outer distal corner and row of spinules along distal border; free exopodal segment slender about 5.3 times longerthan wide (138×26 μm), armed with 2 setae distally and 4 rows of small spinules on dorsomedial surface.

Male. Unknown.

Remarks. Doropygus caribbensis sp. nov. is similar to D. reticulatus sp. nov. in having a thickened and highly sclerotized exoskeleton and in having reticulate ornamentation over the surface of the brood pouch. They differ in the shape and length of the inner coxal setae of legs 1–4, and in the shape of the outer setaon the basis of leg 1. Important additional differences between D. caribbensis sp. nov. and other similar species are summarised in Table 7 .

Figures

FIGURE 218. Doropygus caribbensis sp. nov., female. A, habitus, right; B, reticulation on dorsal surface of prosome; C, urosome, ventral; D, left caudal ramus, lateral; E, antennule; F, antenna; G, labrum; H, mandible; I, maxillule. Scale bars: A, 0.5 mm; B, E–I, 0.05 mm; C, D, 0.1 mm.

FIGURE 219. Doropygus caribbensis sp. nov., female. A, maxilla; B, maxilliped; C, leg 1; D, leg 2; E, leg 4; F, leg 5. Scale bars: 0.05 mm.