Tritonus riambavy, Short, Andrew Edward Z., 2008

Short, Andrew Edward Z., 2008, Revision of the Afrotropical genus Tritonus Mulsant (Coleoptera: Hydrophilidae), Zootaxa 1855, pp. 41-55 : 53-54

Tritonus riambavy sp.n.

( Figs. 3 , 5 , 8 , 11 , 13 , 17 )

Type Material. Holotype (male): “ NHML 742778 MSL 163/ Madagascar: Fianarantsoa: Andringitra N.P./ Riambavy River (female) cascade: alt 1739m / 08:V:2006: Lat –22 8.761 Lon 46 53.495/ Hygropetric habitat, wet rock surfaces next to/ high waterfall: Leg. J. Bergsten Loc P39A” ( NHML). Paratypes (3): Same data as holotype (3, NHML, KSEM).

Diagnosis. See diagnosis of T. steineri .

Description. Total length 6.2–6.6 mm. Color: Dorsum black with general shagreen; with distinct yellow or greenish iridescent patches on elytra. Head. Ground punctation coarse; irregular in size ( Fig. 3 ). Systematic punctures present but only slightly larger than surrounding ground punctures; on clypeus bearing short decumbent setae; those on frons anterior to each eye relatively long and erect. Antennae with club subequal in length to antennomeres 2–6 combined. Maxillary palpi short, apical segment ca. 1.6× length of penultimate segment; penultimate segment distinctly shorter than segment 2. Mentum with anterior margin slightly convex; anterior half with fine transverse microsculpture; entire mentum with fine to moderately coarse, irregularly scattered punctures. Anterior margin of head evenly rounded. Thorax. Ground punctation on pronotum and elytra of very irregular in size, varying from very fine to very coarse. Pronotal and elytral systematic punctures present, but somewhat obscured by coarse ground punctures ( Fig. 5 ), which are similar in size; bearing short setae. Prosternum ( Fig. 8 ) slightly tectiform an indistinct, very narrow and median line that is not distinctly elevated into a carina; not distinctly elevated or dilated at anterior margin. Mesoventrite slightly elevated medially into a carina, with anterior and posterior ends of carina glabrous and more elevated than central, pubescent region. Metasternum with large elevated glabrous region that is three-quarters as wide as long. Metafemora without distinct microsculpture over most of ventral surface. Abdomen. Posteromedial glabrous region of ventrite 1 distinct, ca. 0.15 the width of the ventrite. Glabrous region of ventrite 2 semi-circular to subtriangular in shape; ca. 0.30 the width of the ventrite. Anterior margins of ventrites 1–3 not crenulate, but with a loosely wrinkled appearance. Aedeagus as in Fig. 17 .

Etymology. Named for the river from which it was collected.

Distribution. Madagascar. Known only from the type locality.

Figures

FIGURES 2 – 3. SEMs of head, dorsal and ventral views; 2) T. complanatus; 3) T. riambavy. Scale bar = 1 mm.

FIGURES 4 – 5. SEMs of elytra; 4) T. complanatus; 5) T. riambavy. Scale bar = 1 mm.

FIGURES 6 – 8. SEMs of thoracic sterna of Tritonus species; 6) meso- and metaventrite of T. complanatus, scale bar = 1 mm; 7) prosternum of T. complanatus, 8) prosternum of T. riambavy. Scale bars = 0.5 mm.

FIGURES 11 – 12. Abdomen of Tritonus spp.; 11) T. riambavy; 12) T. crenulatus. Scale bars = 1 mm.

FIGURES 13 – 14. Details of Tritonus spp.; 13) T. complanatus, metafemora, scale bar = 1 mm; 14) T. riambavy, maxillary palpus, scale bar = 0.20 mm.

FIGURES 15 – 21. Aedeagus of Tritonus spp., dorsal view; 15) T. riana; 16) T. steineri; 17) T. riambavy; 18) T. cribratus; 19) T. madagascarensis; 20) T. crenulatus; 21) T. complanatus. Scale bar = 0.45 mm.