Doropygus breviuncinatus, 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 : 374

Doropygus breviuncinatus sp. nov.

( Figs. 247 , 248 )

Typematerial. Holotype (intact ♀, MNHN-IU-2014- 21325 ) anddissectedparatype (♀, figured) from Herdmania momus (Savigny, 1816) , Mont Dore, New Caledonia, Monniot coll.

Etymology. The specific name is derived from Latin brevi (=short) and uncinat (=hooked) and alludes to the short terminal claw of the antenna.

Coxa Basis Exopod			Endopod
Leg 1 0-1 Legs 2 & 30-1 Leg 4 0-1	1-I 0-0 0-0	I-1; I-1; III, I, 4 1-1; 1-1; 3, 1, 5 1-1; 1-1; 2, 1, 5	0-1; 0-1; 1, 2, 3 0-1; 1, 3, 4 0-1; 1, 3, 3

Descriptionoffemale. Body ( Fig. 247A ) narrow, similar in form to D. humilis . Body length 2.75 mm: prosome 2.10 mm long. Dorsalcephalic shield welldefined; metasome indistinctly segmented. Fourth pedigerous somite forming brood pouch, about 1.4 times longer than wide in lateral view, slightly shorter than anterior prosome. Freeurosome ( Fig. 247B ) 5-segmented, cylindrical: genitalsomite 123×314 μm; 4 abdominal somites 205×282, 173×266, 155×244, and 109×216 μm, respectively. Anal somite broadened posteriorly, with deep posteromedian incision. Caudal ramus ( Fig. 247C ) graduallynarrowing distally, about 4.2 timeslongerthan wide (284×68 μm) and 2.6 times longer than anal somite; armed with 6 very small setae; all setae less than half width of ramus at base; 2 proximal setae positioned at 27 and 62% of ramus length.

Rostrum ( Fig. 247D ) consistingof broad proximal third (173 μm wide) and narrower tapering distal twothirds (103 μm wide). Antennule 9-segmented ( Fig. 247E ); 2 proximal segments much broader than distal segments; setae highly entangled, generally of mediumlength, several setae sparsely pinnate. Antenna ( Fig. 247F ) slender, 4-segmented; coxashortand unarmed; basis 120×45 μm, subdistally bearing small knob (exopod) tipped with minute vestigial seta; first endopodal segment 93×47 μm, unarmed, ornamented with patch of minute spinules near middle; compound distal endopodal segment elongate, about 4.4 times longer than wide (128×29 μm); armed with several small setae (distal 3 positioned at base of terminal claw, blunt at tip, subequal in length) plus slightly curved terminal claw ( Fig. 247G ) with blunt tip, 55 μm long, 0.43 times as long as segment; claw ornamented with hyaline membranous fringe along concave margin and on tip.

Labrum ( Fig. 247H ) withsemicircularposteromedian lobe; posteriormargin setulose. Mandible ( Fig. 247I ) with 4 teeth on coxal gnathobase; palp asin D. humilis except exopod bearing 4 large setae only. Paragnath ( Fig. 247J ) with distinct outer subdistal lobule; apical region smooth, without spinules or denticles. Maxillule ( Fig. 247K ) as in D. humilis . Maxilla ( Fig. 247L ) distal syncoxal endite with only 2 setae as in D. humilis . Maxilliped ( Fig. 248A ) incompletely 2-segmented, armedwith 9 and 2 setaeon firstandsecondsegments, respectively.

Leg 1 ( Fig. 248B ) similartothatof D. humilis but inner distal spine on basis shorter, 42 μm long, and spinulose along distal half. Legs 2–4 lacking outer seta on basis ( Fig. 248C, D ); outer setae on second and third exopodal segments unilaterally pinnate along outer margin. Inner coxal seta of leg 4 sparsely pinnate and extending slightly beyond distal border of first endopodal segment. Third exopodal segment of legs 2–4 shorter than wide. Armature formula for legs 1–4 as follows:

Leg 5 ( Fig. 248E ) extending slightly beyond ventrodistal border of genital somite. Protopod as in D. humilis ; exopodal segment about 2.7 times longerthan wide (111×41 μm) with wavymedial margin; armeddistally with 2 setae of 70 μm and 38 μm in length and ornamented with 3 rows of minute spinules on medial surface.

Male. Unknown.

Remarks. Doropygus breviuncinatus sp. nov. resembles D. humilis and D. parahumilis sp. nov. in having a membranous hyaline fringe on the terminal claw of the antenna, but can be readily distinguished from the latter two species by: the proportional length of the caudal ramus of D. breviuncinatus sp. nov. is longer than that of D. humilis , but shorter than that of D. parahumilis sp. nov. In addition, the terminal claw of the antenna of D. breviuncinatus sp. nov. is short (55 μm long) and truncate, in contrast to those of its two congeners, which narrow distally and are more than 70 μm long. Finally, the basis of legs 2–4 of D. breviuncinatus sp. nov. lacks an outer seta which is present, although small, in both of the other two congeneric species. Other differences are summarised in Table 9 .

Figures

FIGURE 247. Doropygus breviuncinatus sp. nov., female. A, habitus, right; B, urosome, ventral; C, left caudal ramus, ventral; D, rostrum; E, antennular segments (with setation omitted); F, antenna; G, distal armature of antenna; H, labrum; I, mandible; J, paragnath; K, maxillule; L, maxilla. Scale bars: A, 0.2 mm; B, C, 0.1 mm; D–F, H–J, 0.05 mm; G, K, L, 0.02 mm.

FIGURE 248. Doropygus breviuncinatus sp. nov., female. A, maxilliped; B, leg 1; C, leg 2; D, leg 4; E, leg 5. Scale bars: 0.05 mm.