Loboixyssimilis, 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 : 536

Loboixyssimilis sp. nov.

( Fig. 357 , 358 )

Typematerial. Holotype (intact ♀, MNHN-IU-2014- 21401 ) , paratypes (5 intact ♀♀, MNHN-IU-2014-21402), and dissected paratypes (2 ♀♀, figured) from Diplosoma multifidum (Sluiter, 1909) , CRRFOCDN 4382-W, Kotor, Palau Islands (07°19.60’N, 134°30.84’E), depth 1 m, 27 November 1996.

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

Etymology. The name is derived from the Latin simil (=similar), referring to the similarity of the new species to L. pilosa sp. nov. and L. palauensis sp. nov.

Descriptionoffemale. Body ( Fig. 357A ) swollen, surfacecoveredwithsetules.Prosome1.21mmlong;dorsal cephalic shield lacking posterolateral horn-like processes. Metasomeindistinctly 4-segmented by 3 constrictions dorsally and laterally; fourth pedigerous somite greatly expanded, forming spherical brood pouch, about 810 μm in diameter. Free urosome ( Fig. 357B ) inserted into ventral surface of brood pouch; 5-segmented: genital and 4 abdominalsomites 30×139, 58×133, 53×121, 44×108, and 53×110 μm, respectively. Caudalramus ( Fig. 357B ) broad, 1.24 times longer than wide (57×46 μm) and as long as anal somite, tapering, with rounded distal margin; armedwith 2 or 3 smallsetae.

Rostrum ( Fig. 357C ) slightly longer than wide (100×91 μm); wider in proximal quarter, narrower and tapering in distal three-quarters; surface covered with setules.Antennule ( Fig. 357D ) short, stronglytapering, 97 μm long, 7-segmented; armature formula uncertain due to similarity between setae and setules. Antenna ( Fig. 357E ) 3-segmented; coxaandbasisunarmed; unsegmented endopod slender, 4.3 times longerthan wide (65×15 μm), aslongas basis; armedwith 5 smallsetae (arranged as 1, 2, and 2) plus small terminal claw, about 0.3 times as long as basis.

Labrum ( Fig. 357F ) weak, with smooth, convex posteriormarginandpaired,setuloselobesposterolaterally. Mandible ( Fig. 357G ) with 5 acute teeth and 1 setaon coxalgnathobase: basiswith 1 setaonmedial margin; exopod with 5 setae (outermost distal seta longer than other 4): endopod with 1 and 4 setae on first and second segments, respectively; 2 longer distal setae on second segment naked, other setae pinnate. Maxillule ( Fig. 357H ) with basis and endopod fused; precoxal arthrite armed with 6 setae; coxal endite and epipodite lacking; fused basis and endopod armed with 1 medial and 3 distalsetae; exopodwith 4 setae. Maxilla ( Fig. 357I ) 4- segmented; syncoxawith with 3, 2, and 2 setaeon first to third endites, respectively; basis with 1 thick seta and 1 small seta; endopod with 1 thick setaon first segment and 1 thick and 2 thin setae on second. Maxilliped ( Fig. 357J ) as unsegmented lobe bearing 6 setae and outer distal ornamentation of minute spinules.

Legs 1–4 ( Fig. 358 A-D) biramous with incompletely 2-segmented protopods; innercoxalsetaabsent. Leg 1 basis with inner distal seta. Endopods 2-segmented in legs 1–4; exopods obscurely segmented, with trace of articulation in leg 1, and traces of 2 articulations in legs 2–4. Protopods and rami of legs 1–4 ornamented with setules; all setae short and naked. Armature formula of legs 1–4 as follows:

Leg 5 ( Fig. 357B ) rudimentary, bilobed; outer lobe tapering; each lobe tipped with small seta.

Male. Unknown.

Remarks. Loboixys similis sp. nov. is similar to L. palauensis sp. nov. in the possession of 6 setae on the arthrite of the maxillule, in the absence of a coxal epipodite on the same appendage, and in the possession of 2-segmented endopods inlegs 1–4. However, in L. similis sp. nov. the caudalramus is shorter (1.24 times longer than wide, compared to 1.6 times in L. palauensis sp. nov.) and has fewer setae, the setae on the maxillule are pinnate (cf. naked in L. palauensis sp. nov.), and there are fewer setae on legs 1–4 in L. similis sp. nov. than in L. palauensis sp. nov.

Loboixyssimilis sp. nov., L. pilosa sp. nov. and L. palauensis sp. nov. were all found living in association with the same ascidian host Diplosoma multifidum in the tropical Pacific. Theirdetailed differencesare summarised in Table 12 .

Figures

FIGURE 357. Loboixys similis sp. nov., female. A, habitus, left; B, leg 5 and urosome, ventral; C, rostrum; D, antennule; E, antenna; F, labrum; G, mandible; H, maxillule; I, maxilla; J, maxilliped. Scale bars: A, 0.2 mm; B, C, 0.05 mm; D–J, 0.02 mm.

FIGURE 358. Loboixys similis sp. nov., female. A, leg 1; B, leg 2; C, leg 3; D, leg 4. Scale bars: 0.02 mm.