Exalloniscus convexus, Taiti & Cardoso, 2020

Exalloniscus convexus View in CoL n. sp.

Figures 19-21, 22H

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Material examined

LAOS: Holotype: ♂, ( MNHN), Vang Vieng, Tham None, 18°57’04.7”N 102°26’01.7”E, 240 m a.s.l., cave, 1.I.2000, leg. L. Deharveng and A. Bedos. GoogleMaps Paratypes: 2 ♀♀ ( MNHN) , 1 ♂, 2 ♀♀ ( MZUF), same data as holotype GoogleMaps .

Description

Maximum length: ♂ and ♀ 7 mm. Body moderately convex ( Figure 19A); colourless ( Figure 22H). Dorsum with scattered triangular and pointed scale-setae ( Figure 19B); noduli laterales as in all other species of Exalloniscus . Cephalon ( Figure 19C,D) with lateral lobes triangular with narrow apices, distinctly protruding laterally; frontal and suprantennal line slightly bent down in middle; eyes absent. Pereonites with posterior margins slightly concave at sides, with postero-lateral corners rounded, slightly bent backwards ( Figure 19E). Pleonites 3-5 with epimera well developed and broad, continuous with pereon outline ( Figure 19A,F). Telson triangular, wider than long, with straight sides and broadly rounded apex, much shorter than tips of epimera of pleonite 5 ( Figure 19F). Antennula ( Figure 19G) third article with five subapical and two apical aesthetascs. Antenna elongated ( Figure 19H) with fifth article of peduncle as long as flagellum; ratio of flagellum joints 7:6:10; second and third article of flagellum each with one row of several aesthetascs. Buccal pieces ( Figure 20) as in E. nepalensis except for maxillula ( Figure 20C) outer branch with only one seta on caudal surface, and maxilliped ( Figure 20E) palp with basal article with one seta. Pereopods elongated; dactylar seta flagelliform, setose at apex. Pereopod 1 ( Figure 21B) carpus with transversal antennal grooming brush. Pereopod 7 ( Figure 21C) basis with distinct water conducting system. Uropod ( Figure 21A) exopod slightly longer than endopod.

Male: Pereopod 1 carpus and merus with few long setae on sternal margin ( Figure 21B). Pereopod 7 ( Figure 21C) ischium with sternal margin straight. Pleopod 1 ( Figure 21D) exopod triangular, longer than wide, with outer margin slightly concave, posterior point narrow with rounded apex; endopod with pointed distal part distinctly bent outwards. Pleopod 2 ( Figure 21E) exopod triangular, outer margin deeply concave and truncate posterior point; endopod flagelliform, longer than exopod. Pleopod 3-5 exopods ( Figure 21 F-H) triangular with few setae on outer margin.

Etymology

Latin: convexus = convex. The name refers to the moderately but distinct convex body of the new species, a unique character within the genus.

Remarks

The new species is readily distinguished from all the other species in the genus in having convex, instead of flat, body, epimera of pleonites 3-5 broader, telson distinctly shorter than epimera of the pleonite 5, elongated appendages, antenna with third article of flagellum distinctly longer than each second and first, and the characteristic shape of the male pleopod 1 endopod with a pointed distal part distinctly directed outwards.