Tritonus cribratus ( Mulsant, 1844 )

Short, Andrew Edward Z., 2008, Revision of the Afrotropical genus Tritonus Mulsant (Coleoptera: Hydrophilidae), Zootaxa 1855, pp. 41-55 : 49-51

Tritonus cribratus ( Mulsant, 1844)

( Fig. 18 )

Cyclonotum cribratum Dejean, 1833: 134 . nomen nudum. Hydrobius cribratus Mulsant, 1844: 377 .

Tritonus cribratus ( Mulsant) ; Mulsant, 1844: 378.

Material Examined (7). MAURITIUS: “Cabinet”, iv.1957, J. Vinson (3, NHML); “Cabinet”, 26.xii.1957, J. Vinson (1, NHML); “Cabinet”, 8.ii.1958, J. Vinson (3, KSEM, NHML).

Diagnosis. In addition to being the only species presently known from Mauritius, T. cribratus can be distinguished by the exceptionally coarse systematic punctures and fine to almost obscure ground punctures, the low, finely but evenly carinate mesoventrite, and evenly microreticulate metafemora.

Description. Total length 6.3–6.9 mm. Color. Dorsum black with a general shagreen. Pronotum with dark black patches around margins. Elytra with bright iridescent blue-green spots on lateral halves. Head. Ground punctation irregular in size, composed of fine to moderately coarse punctures Systematic punctures much larger, ca. 4× the size of largest surrounding ground punctures; on clypeus bearing short decumbent setae; those on frons anterior to each eye relatively long and erect. Antennae with club subequal to slightly longer in length to segments 2–6. Maxillary palpi short, apical segment ca. 1.6× length of penultimate segment; penultimate segment slightly shorter than segment 2. Mentum with anterior margin convex; anteriorly with fine to moderately coarse, transverse microsculpture; posteriorly with irregularly scattered punctures. Anterior margin of head subquadrate, broadly and evenly rounded. Thorax. Ground punctation on pronotum and elytra of dense and fine; composed of irregular sizes and slightly smaller than those of the head. Pronotal systematic punctures very large and distinct; bearing short setae. Elytral systematic punctures bearing short setae and similar in size to slightly larger than pronotal systematic punctures. Prosternum strongly bulged centrally, with a low but distinct, narrowly glabrous median carina; without an anteromedial tooth. Mesoventrite with slightly elevated region centrally with a distinct linear carina; surface of carina glabrous. Metasternum with very large elevated pentagonal glabrous region, almost twice as wide as long. Metafemora mostly covered with weakly impressed microsculpture except for central region. Abdomen. Posteromedial glabrous region of ventrite 1 present but very small, ca. one fourth to one fifth as wide as region on ventrite 2. Glabrous region of ventrite 2 moderately broad, hemispherical in shape; one fourth the width of the ventrite. Anterior margins of ventrites 1–3 not crenulate, but with a loosely wrinkled appearance. Aedeagus as in Fig. 18 .

Distribution. Endemic to Mauritius ( d’Orchymont 1929, Bameul 1986).

Figures

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.