Sympygus punctatus, 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 : 413-416

Sympygus punctatus gen. et sp. nov.

( Figs. 273 , 274 )

Typematerial. Holotype (intact ♀, MNHN-IU-2014- 21340 ) , paratypes (2 intact ♀♀, MNHN-IU-2014- 21341), and dissected paratypes (2 ♀♀, figured) from Cnemidocarpa pedata (Herdman, 1881) (MNHN-IT-2008-2243 = MNHN S1/ CNE /207), CRRF OM 91- 5561-F, Sarawak, NW of Miri, Malaysia (05°53.34 Ń, 112°39.72 É), depth 6 m, 31 March 2003.

Etymology. The specific name is derived from the Latin punctat, meaning “marked with punctures”. It alludes to the numerous pits ornamenting the body surface of the new species.

Descriptionoffemale.Body( Fig.273A )compressed, Doropygus -shaped, with firm, thick exoskeleton ornamented with numerous pore-like pits on surface. Bodylength 1.14 mm; prosome 1.03 mmlong, clearly 5-segmented. Dorsalcephalic shield broad, expanded ventrolaterally.Fourthpedigeroussomiteformingelliptical brood pouch, 510×320 μm in lateral view. Free urosome ( Fig. 273B ) slender, graduallynarrowingposteriorly, wellsclerotized, 5-segmented: genitalsomite 113×128 μm, with convex lateral margins; 4 abdominal somites 74×84, 81×67, 56×57, and 41×48 μm, respectively. Anal somite with shallow posteromedian incision. Caudal ramus ( Fig. 273C ) about 2.6 times longerthanwide (46×18 μm) but only slightly longer than anal somite: armed with 6 long, naked setae (outer proximal, dorsal, and 4 distal); outer proximal seta positioned slightly distal to midlength of ramus; dorsal seta positioned subdistally.

Rostrum ( Fig. 273D ) as short anteroventral prominence on frontal margin of cephalosome, not articulated at base. Antennule ( Fig. 273E ) slender, 194 μm long, 9-segmented; proximal segmentsnot markedly broader; armatureformula 3, 12, 5, 4+aesthetasc, 4, 3+aesthetasc, 2, 2+aesthetasc, and 7+aesthetasc; setae crowded, 2 pinnate setae on first segment, all other setae naked. Antenna ( Fig. 273F ) 4-segmented; short coxa unarmed; basis 37×22 μm, with vestigial seta at outer distal corner; first endopodal segment 39×24 μm, with small seta subdistally on inner margin; compound distal segment about 3.0 times longer than wide (48×16 μm): armed with 8 setae arranged as 1, 3, 1, 1, and 2 (all setae attenuated at tip) plus terminal claw about 23 μm long.

Labrum ( Fig. 273G ) with smooth, semicircular posteromedianlobeand patchesof setulesposterolaterally. Mandible ( Fig. 273H ) with narrow coxal gnathobase bearing 2 teeth on cutting edge: basis with 1 setaon medial margin; exopod armed with 4 setae, third seta larger than others; endopod 2-segmented, armed with 4 setae on first segment and 10 setae (5 mediodistal setae naked) on second. Maxillule ( Fig. 273I ) with produced arthrite bearing 8 setae; coxa with 2 unequal setae on epipodite, but lacking endite; basis, exopod and endopod fully fused with one another, forming single complex armed with 7 setae, second medial seta much larger than others. Maxilla ( Fig. 274A ) 5-segmented; syncoxawith 3 endites bearing 3, 2, and 2 setae, respectively, on first to third endites; basis with 2 setae, distal seta two-thirds length of proximal; endopod with 1, 1, and 3 setae on first to third segments, respectively; 3 endopodal setae (1 on each segment) ornamented with array of thick, comb-like setules along concave margin. Maxilliped ( Fig. 274B ) unsegmentedbut divisible intobroad proximal and narrow distal parts; armed with 5 medial setae on proximal part and 2 unequalapicalsetae.

Leg 1 ( Fig. 274C ) biramous with 3-segmented rami. Inner coxal seta broad, extending to distal tip of endopod. Inner distal spine on basis robust, 31 μm long, reaching beyond distal border of second endopodal segment. Inner seta on first exopodal segment and 2 proximal inner setae on third exopodal segment broadened. Outer spines on second and third exopodal segments small. Legs 2–4 with 3-segmented exopods and 2-segmented endopods ( Fig. 274D, E ). Inner coxal seta absent in leg 4. Outer and distal setae on exopods and endopods of legs 2–4 naked. Leg 4 lacking inner setaon first exopodal segment. Armature formula for legs 1–4 as follows:

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

Leg 5 ( Fig. 274F ) 2-segmented: protopod expanded distolaterally, much wider than long, armedwith large, naked seta at outer distal corner; free exopodal segment about 2.2 times longer than wide (28×13 μm), broad in middle; armed with 2 unequal, naked setae distally (long outer and short inner), ornamented with 2 clusters of fine spinules on medial surface.

Male. Unknown.

Remarks. Thisdistinctive species iscurrently known only from the type locality in Malaysia.

Figures

FIGURE 273. Sympygus punctatus gen. et sp. nov., female. A, habitus, right; B, urosome, ventral; C, left caudal ramus, dorsal; D, rostrum; E, antennule; F, antenna; G, labrum; H, mandible; I, maxillule. Scale bars: A, 0.1 mm; B, D, 0.05 mm; C, E– I, 0.02 mm.

FIGURE 274. Sympygus punctatus gen. et sp. nov., female. A, maxilla; B, maxilliped; C, leg 1; D, leg 2; E, leg 4; F, leg 5. Scale bars: 0.02 mm.