Doroixysfijiensis, 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 : 483-485

Doroixysfijiensis sp. nov.

( Figs. 320 , 321 )

Typematerial. Holotype (intact ♀, MNHN-IU-2014- 21371 ) and paratype ♀ (dissected, MNHN-IU-2014- 21372) from Eucoelium mariae (Michaelsen, 1924) (MNHN-IT-2008-6923 = MNHN P3/ POL.B/04), CRRF-OCDN 4237-P, Fiji (18°18,08’S, 178°01,05’E), depth 12 m, 29 October 1996.

Etymology. The specific name of the new species is derived from its type locality, Fiji.

Descriptionoffemale. Body ( Fig. 320A ) curved ventrally, 1.07 mmlong. Prosome 836 μmlong, consisting of cephalosome and distinctly 4-segmented metasome. Dorsal cephalic shield with prominent paired horn-like process ( Fig. 320D ) posterolaterally, each bearing 2 small tuberclesdistally. Fourthpedigeroussomiteslightlylonger than anterior part of metasome. Free urosome ( Fig. 320B ) 5-segmented. Anal somite and caudal rami ornamented with numerous setules on all surfaces. Caudal rami divergent, evenly tapering; ramus ( Fig. 320C ) about 3.1 times longer than wide (89×29 μm) and 1.6 times longer than anal somite: armed with 6 setae (outer lateral, dorsal, and 4 distal); outer lateral and dorsal setae positioned at 43 and 51% of ramus length; all caudal setae naked and shorter than width of ramus at base.

Rostrum ( Fig. 320E ) 82×50 μm, bearing scattered setules; lateral margins parallel proximally, and evenly tapering over distal four-fifths. Antennule ( Fig. 320F ) 110 μmlong, 7-segmented; armatureformula 2, 13, 4, 3+aesthetasc, 2, 2+aesthetasc, and 12+aesthetasc; setae moderately long, all naked. Antenna ( Fig. 320G ) consistingof coxa, basis, and 2-segmented endopod; proximal 3 segments unarmed; endopodal segments with few setules; compound distal endopodal segment about 2.9 timeslongerthan wide (40×14 μm): armedwith 6 smallsetae (grouped as 1, 2, and 3) plusterminal claw, more than half length of distal endopodal segment.

Labrum ( Fig. 320H ) simple, denselysetulose posteriorly. Mandible ( Fig. 320I ) with 5 teethand 1 seta on coxal gnathobase; basis with 1 seta on medial margin: exopod with 5 setae (innermost and outermost subequal in length and both about 0.6 times as long as 3 larger middle setae): endopod 2-segmented; first segment with 1 broad setaonmedial margin; secondwith 4 setae, outerdistalseta longest (1.5 timeslongerthan mediodistalseta). Maxillule ( Fig. 320J ) lacking coxal endite and armed as usual: 9 seta on arthrite, 1 on epipodite, 1 on basis, 4 on exopod, and 3 on endopod. Maxilla ( Fig. 320K ) 4-segmented; syncoxa with 4, 2, and 3 setae (including minute proximal seta) on first to third endites, respectively; basis with smooth clawplus 1 seta; endopod with 1 and 3 setaeon first and second segments, respectively. Maxilliped ( Fig. 321A ) unsegmented, tapering distally, armed with 6 setae and ornamented with spinules along outer margin,

Legs 1–4 with 3-segmented rami ( Fig. 321 B-D); inner seta absent on coxa of all legs. Leg 1 lacking inner distal spine on basis. First endopodal segment of leg 1 broad. Legs 2 and 3 with same armature formula. All setae on legs 2–4 naked and bluntly tipped. Distal seta on third endopodal segment short in left leg 4 (as in Fig. 321D ) but longer in right leg 4. Armature formula for legs 1–4 as follows:

	CoxaBasis Exopod			Endopod
Leg 1	0-0	1-0	I-1; I-1; I+1, 1, 40-1; 0-1; 1, 2, 3
Legs 2 & 30-0		1-0	1-0; 1-0; 3, 1, 5	0-0; 0-0; 0, 2, 2
Leg 4	0-0	1-0	1-0; 1-0; 3, 1, 4	0-0; 0-0; 1

Leg 5 ( Figs. 320B , 321E ) represented by blunt posteroventral lobe on somite tipped with protopodal seta and tapering inner process (representing exopod) bearing 1 small seta and 1 tubercle on subdistal outer margin, ornamented with several setules scattered on ventral surface.

Male. Unknown.

Remarks. The lack of an inner distal spine on the basis of leg 1 is shared between only three species, D. fijiensis sp. nov., D. gryphina sp. nov. and D. nodulosa sp. nov. Both D. fijiensis sp. nov. and D. gryphina sp. nov. have caudal rami with a length/width ratio of about 3.0 or 3.1:1, a setulose anal somite and caudal rami, and distinctly 3-segmented endopods inlegs 2 and 3. In contrast, in D. nodulosa sp. nov. the caudal rami are only 2.0 timeslongerthan wide, theanal somiteand caudalrami are not setulose, and the endopods of legs 2 and 3 are only 2-segmented. Marked differences between D. fijiensis sp. nov. and D. gryphina sp. nov. include the distal endopodal segments of legs 2 and 4 which are armed with 4 and 1 setae, respectively, in D. fijiensis sp. nov. (comparedto 5 and 0 setae, respectively, in D. gryphina sp. nov.), and the medial and outermost setae on the mandibular exopod are 0.6 times as long as the 3 middle setae whereas in D. gryphina sp. nov. the medial seta is not shorter than 3 middle setae and the outermost seta is about half as long as the other 4 setae.

Figures

FIGURE 320. Doroixys fijiensis sp. nov., female. A, habitus, left; B, leg 5 and urosome, ventral; C, left caudal ramus, dorsal; D, posterolateral process of cephalic shield; E, rostrum; F, antennule; G, antenna; H, labrum; I, mandible; J, maxillule; K, maxilla. Scale bars: A, 0.1 mm; B, 0.05 mm; C–K, 0.02 mm.

FIGURE 321. Doroixys fijiensis sp. nov., female. A, maxilliped; B, leg 1; C, leg 2; D, leg 4; E, leg 5. Scale bars: 0.02 mm.