Doroixys nodulosa, 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 : 478-483

Doroixys nodulosa sp. nov.

( Figs. 318 , 319 )

Typematerial. Holotype (intact ♀, MNHN-IU-2014- 21369 ) , paratypes (3 intact ♀♀, MNHN-IU-2014-21370), anddissectedparatype (♀, figured) from Leptoclinides oscitans Monniot F. & Monniot C., 1996 (MNHN-IT-2008-4814 = MNHNA 2/ LEP /67), CRRFOCDN 4379- T, Palau, Ngemelis, Bailechesengel Island, (07°06.22’N, 134°15.06’E), depth 20 m, 26 November 1996.

Additional material. 2 ♀♀ (MNHN-IU-2018- 1905) from L. oscitans, CRRFOCDN 3434- R, Davao Philippines; 1 ♀ (dissected) from L. oscitans , Indonesia, collected by Ireland, 01 May 1996.

Etymology. The specific name refers to the presence of nodule-like tubercles on the posterolateral processes of the cephalic shield.

Descriptionoffemale. Body ( Fig. 318A ) moderately inflated, 1.00 mmlong. Prosome straight, 740 μm long, gradually broadening distally; dorsal cephalic shield with paired, sclerotized horn-likeprocesses posterolaterally, each with 2 small tubercles distally ( Fig. 318B ). Free urosome ( Fig. 318C ) 5-segmented, articulations indistinct: genital and 4 abdominal somites 47×103, 40×102, 37×79, 31×75, and 45×70 μm, respectively. Lateral margins of genital and first abdominal somites convex when viewed together. Anal operculum not developed. Caudal rami ( Fig. 318D ) stout, divergent, incompletely articulated from anal somite; ramus 2.0 times longerthan wide (42×21 μm), tapering, slightly shorter than anal somite: armed with 6 setae (2 outer and 4 distal); 2 outer setae located at 42 and 62% of ramus length; second outer seta shorter than other 5 setae.

Rostrum 1.35 timeslongerthan wide, taperingtoblunt apex ( Fig. 318E ), ornamented with few setules. Antennule ( Fig. 318F ) 117 μmlong, 7-segmented; armatureformula 2, 14, 4+aesthetasc, 3+aesthetasc, 2, 3, and 7+aesthetasc; all setae naked; aesthetascs small. Antenna ( Fig. 318G ) 4- segmented; proximal 3 segments unarmed; basis shorter than first endopodal segment; compound distal endopodal segment about 2.8 times longer than wide (33×12 μm): armed with 5 setae (arranged as 1, 2, and 2) plus small terminal claw, about half as long as segment.

Labrum ( Fig. 318H ) unornamented; posterior part bullate and soft. Mandible ( Fig. 318I ) with 5 teeth and 1 seta on coxal gnathobase, as usual: basis with 1 seta near middle of medial margin; exopod with 5 setae (3 middistal setae subequal in length and longer than medial seta; outermost seta about half as long as longer middle setae): endopod with 1 broad seta on first segment and 4 setae (shorter medial and outer, and 2 longer distal) on second. Maxillule ( Fig. 318J ) with 9 setaeon arthrite, 1 each on epipodite and basis, 4 on exopod and 3 one endopod; 2 outer distal setae on endopod equal in length, both longer than medial seta. Maxilla ( Fig. 319A ) 4- segmented, armedwith 8 setaeonsyncoxa (4, 2, and 2 on first to third endites, respectively), smooth claw plus 1 setaon basis, and 1 and 3 naked setae on first and second endopodal segments, respectively. Maxilliped ( Fig. 318K ) unsegmented, armed with 6 distal setae, and ornamented with fine spinules along outer margin.

Leg 1 ( Fig. 319B ) and leg 4 ( Fig. 319E ) with 3- segmented rami; first endopodal segment of leg 1 broad. Legs 2 and 3 ( Fig. 319C, D ) with 3-segmented exopods and 2-segmented endopods; distal endopodal segment of legs 2 and 3 each bearing trace of articulation in middle. Inner coxal seta absent in all swimming legs. Inner distal element absent on basis of leg 1. Inner setae on exopod of leg 1 pinnate, but all other setae on swimming legs naked. All setae on legs 2–4 bluntly tipped. Inner setae on third exopodal segment of right legs 2 and 3 shorter than those of left legs 2 and 3. Endopod of leg 4 half as long as exopod; third endopodal segment unarmed or armed with 1 distal seta. Armature formula for legs 1–4 as follows:

	Coxa	Basis	Exopod	Endopod
Leg 10-0	10-0	1-0	I-1; I-1; I+1, 1, 4	0-1; 0-1; 1, 2, 3
Leg 20-0	20-0	1-0	1-0; 1-0; 3, 1, 5	0-0; 1, 2, 2
Leg 30-0	30-0	1-0	1-0; 1-0; 3, 1, 5	0-0; 1, 2, 1
Leg 40-0	40-0	1-0	1-0; 1-0; 3, 1, 4	0-0; 0-0; 1 (or 0)

Leg 5 ( Fig. 319F ) represented by blunt posteroventral lobe on surface of somite, tipped with 1 thin seta, plus tapering inner process (representing exopod) bearing 1 small seta and 1 tubercle on subdistal outer margin.

Male. Unknown.

Remarks. Doroixys nodulosa sp. nov. resembles D. gryphina sp. nov. more closely than other congeners: both these new species share the absence of an inner distal spine on the basis of leg 1, the possession of 2 distal tubercles on the posterolateral horn-like processes of the dorsal cephalic shield, a single subdistal tubercle on the exopodal process of leg 5, and similar setation on the endopods of legs 2–4. They were also found in the same geographical region, Indonesia. However, they are not conspecific and can be differentiated by the caudal ramus, which is 2.0 times longer than wide in D. nodulosa sp. nov. compared with 3.0 times longer in D. gryphina sp. nov., the rostrum has an acutely pointed tip in D. nodulosa sp. nov. whereas it is bluntly tipped in D. gryphina sp. nov., and there are other minor differences in the length and pinnation of the setae on the mandibular exopod, the maxilla, and leg 1.

Figures

FIGURE 318. Doroixys nodulosa sp. nov., female. A, habitus, right; B, posterolateral process of cephalic shield; C, leg 5 and urosome, ventral; D, caudal rami, dorsal; E, rostrum; F, antennule; G, antenna; H, labrum; I, mandible; J, maxillule; K, maxilliped. Scale bars: A, 0.1 mm; B, D–K, 0.02 mm; C, 0.05 mm.

FIGURE 319. Doroixys nodulosa sp. nov., female. A, maxilla; B, leg 1; C, leg 2; D, leg 3; E, leg 4; F, leg 5. Scale bars: 0.02 mm.