Demoixys depressa, 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 : 547-549

Demoixys depressa sp. nov.

( Figs. 365 , 366 )

Typematerial. Holotype (intact ♀, MNHN-IU-2014- 21407 ) , paratypes (2 intact ♀♀, MNHN-IU-2014-21408), and dissected paratypes (2 ♀♀, figured) from Diplosoma versicolor Monniot F., 1994 (MNHN-IT-2008-3648 = MNHNA 2/ DIP /147), CRRFCRCHO 139, Caminguin I., the Philippines (09°12.89’N, 124°38.03’E), 18 April 1997.

Etymology. The specific name alludes to the dorsoventrally depressed body of the new species.

Descriptionoffemale. Body ( Fig. 365A, B ) swollen, 1.94 mm long. Prosome curved ventrally, depressed, makedly broaderposteriorly, 1.03 mm wide, and 0.79 mm dorsoventral depth. Cephalosome directed posteriorly; dorsal cephalic shield distinct, small in relation to metasome, lacking posterolateral processes. Metasome unsegmented, with 2 dorsal constrictions anteriorly; posterolateral part more expanded than anterior and middle regions; entire metasome forming brood pouch. Freeurosome ( Fig. 365C ) short, slightly widerthan long, 5-segmented, but genital somite fused with metasome. Caudal rami fused with anal somite, without trace of articulation, strongly tapering, nearly as long as wide, setulose but lacking setae.

Rostrum ( Fig. 365D ) large, slightly wider than long, semicircular, with scattered setules. Antennule ( Fig. 365E ) short, broad, 90 μm long, 1.5 times longer than wide, incompletely 5-segmented; articulations expressed only on posterior surface of appendage; few setae indistinguishable from scattered setules. Antenna ( Fig. 365F ) 3-segmented, consistingof coxa, basis, and unsegmentedendopod; coxaandbasisunarmed; endopod about 2.7 timeslongerthan wide (41×15 μm): armed with 5 setae (arranged as 1, 2, and 2) plus short terminal claw, aboutone-thirdaslongas endopod.

Labrum ( Fig. 365G ) semicircular, much widerthan long, unornamented. Mandible ( Fig. 365H ) with broad coxal gnathobase bearing 4 teeth; proximal second tooth smaller: basiswith 1 seta medially; exopod with 5 setae; proportional lengths of setae 12:13:15:16:10 from inner to outer; endopod with 1 broad seta on first segment and 4 (2 medial and 2 distal) subequal setae on second. Maxillule ( Fig. 365J ) with 7 setae on arthrite, 1 on each epipodite and basis, 4 on exopod, and 3 on endopod; endopod incompletely defined from basis; coxal endite absent. Maxilla ( Fig. 365I ) 3-segmented; syncoxawith 3, 2, and 2 setae on first to third endites, respectively; basis with claw plus 1 seta; endopod unsegmented with 4 setae. Maxilliped ( Fig. 366A ) as small lobe armed with 6 naked setae.

Legs 1–3 ( Fig. 366 B–D) rudimentary, each represented by 2 unsegmented lobes; coxa and basis not defined. Leg 1 with 9 setae on exopodal lobe and 4 on endopodal lobe. Leg 2 with 7 setae on exopodal lobe and unarmed endopod. Leg 3 with 4 setae on exopodal lobe and 2 setae on endopodal lobe. Setae on legs 1–3 small or rudimentary. Legs 4 and 5 absent.

Male. Unknown.

Remarks. Demoixys depressa sp. nov. may be distinguished from its congeners by the absence of legs 4 and 5. The dorsoventrally depressed body and the possession of 4 setae on the unsegmented endopod of the maxilla are also distinguishing character states of the new species.

Figures

FIGURE 365. Demoixys depressa sp. nov., female. A, habitus, right; B, habitus, ventral; C, urosome, ventral; D, rostrum; E, antennule; F, antenna; G, labrum; H, mandible; I, maxilla; J, maxillule. Scale bars: A, B, 0.2 mm; C, 0.1 mm; D–J, 0.02 mm.

FIGURE 366. Demoixys depressa sp. nov., female. A, maxilliped; B, leg 1; C, leg 2; D, leg 3. Scale bars: 0.01 mm.