Tritonus crenulatus, Short, Andrew Edward Z., 2008

Short, Andrew Edward Z., 2008, Revision of the Afrotropical genus Tritonus Mulsant (Coleoptera: Hydrophilidae), Zootaxa 1855, pp. 41-55 : 48-49

Tritonus crenulatus sp.n.

( Figs. 12 , 20 )

Type Material. Holotype (male): “ MADAGASCAR / Antananarivo/ Manakambahiny/ 15 February 1990 / W. E. Steiner”, “In seepage over/ exposed granite/ cliff face”. ( NMNH). Paratypes (16). same data as holotype (16, NMNH, NMPC, KSEM).

Diagnosis. The coarsely crenulate anterior margins of abdominal ventrites 2 and 3 will serve to distinguish this species from all others. It is very similar to the slightly smaller T. riana , but this species has much less coarse crenulations.

Description. Total length 7.1–7.6 mm. Color: Dorsum black with general shagreen. Pronotum with a few dark black patches around margins. Elytra with indistinct green iridescent patches along lateral margins. Head. Ground punctation fine but distinct; irregular in size. Systematic punctures distinct; 3× as large as largest surrounding ground punctures; on clypeus bearing short decumbent setae; those on frons anterior to each eye relatively long and erect. Antennae with club distinctly shorter in length than antennomeres 2–6 combined. Maxillary palpi short, apical segment ca. 1.2× length of penultimate segment; penultimate segment and segment 2 subequal in length. Mentum with anterior margin slightly convex; anterior half with fine to very fine, transverse microsculpture; entire mentum with fine, irregularly scattered punctures. Anterior margin of head moderately wide and broadly rounded. Thorax. Ground punctation on pronotum and elytra fine, slightly finer than ground punctation on head. Pronotal and elytral systematic punctures large and distinct; bearing short setae. Prosternum slightly tectiform with a sharp, narrow and glabrous median carina; not distinctly elevated or dilated at anterior margin. Mesoventrite elevated medially into a carina, with anterior half slightly more elevated than posterior half; surface of carina narrowly glabrous. Metasternum with large elevated glabrous region that half as wide as long. Metafemora glabrous and shiny on basal third; apical two thirds dull, with moderately impressed microsculpture in the form of fine transverse wavy lines. Abdomen. Posteromedial glabrous region of ventrite 1 moderately small, slightly more than half as wide as glabrous region on ventrite 2. Glabrous region of ventrite hemi-ovoid to subtriangular in shape; about one third the width of the ventrite. Anterior margin of ventrite 2 coarsely and deeply crenulate; margins of ventrites 1, 3 and 4 weakly but distinctly crenulate. Aedeagus as in Fig. 20 .

Etymology. Named for the coarsely crenulate margins of abdominal ventrites 2 and 3, which are distinctive of this species.

Distribution. Madagascar. Known only from the type locality.

Figures

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