Triodontus modestus (Benderitter, 1914)

Frolov, Andrey V., Montreuil, Olivier & Akhmetova, Lilia A., 2016, Review of the Madagascan Orphninae (Coleoptera: Scarabaeidae) with a revision of the genus Triodontus Westwood, Zootaxa 4207 (1), pp. 1-93 : 72

Triodontus modestus (Benderitter, 1914)

( Figs. 36 A–H)

Orphnidius modestus Benderitter, 1914a: 291 . Triodontus modestus Paulian, 1977: 1222 .

Type material examined. Lectotype (here designated) ( Figs. 36 A, B, D–G), male, “ Mianinarévo [Miarinarivo] / MADAGASCAR Collection Le Moult / Orphnus ♂ modestus type E. Benderitter det. / Orphnus modestus Bend . LECTOTYPUS Frolov des. 2010” (MNHN).

Paralectotypes: one male and four females with the same locality data as the lectotype ( MNHN) .

Additional material examined. MADAGASCAR. Antananarivo: one female, “ Madagascar Tananarive Collection Le Moult [Antananarivo]” ( MNHN) ; Madagascar (no precise locality): one female, “Museum Paris Madagascar Collection Leon Fairmaire 1906” ( MNHN) .

Diagnosis. Triodontus modestus can easily be separated from other Triodontus species with 2 tubercles on the pronotal bulge by being smaller (body length up to 6.5 mm whereas the other species are longer than 9.0 mm), and having outer lobes of the parameres with large circular situations lateroapically. All examined specimens are light brown but additional material is needed to clarify if such a pale coloration is species specific.

Description. Male. Body convex, strongly shiny, with uniform light brown coloration ( Figs. 36 A–B).

Frontoclypeus slightly convex anteriorly, obtusely rounded laterally, anterior margin setose in dorsal view. Eyes small (diameter a few times smaller than distance between eye and gula in ventral view), incompletely divided by canthus into small dorsal and large ventral parts. Frontoclypeus with small tubercles mediad of each eye and with short, tubercle-like horn in the center of the frontoclypeus. Frontoclypeus coarsely punctate apical of the horn.

Pronotum without a distinct medial tubercule but with 4 relatively small tubercles in proximal 1/3, and with a shallow excavation anteriad of the tubercles. Lateral margins with wide, densely setose border. Anterior margin with wide, smooth border. Posterior margin with fine border, not crenulate; punctate with small, narrow, longitudinal punctures. Surface of pronotum sparsely punctate with small punctures.

Scutellum rounded apically, its visible part is about 1/15 length of elytra.

Elytra convex, with distinct humeral humps. Maximum width approximately at the middle. Elytra with 10 striae on disc and with oblique line from base of 6th stria to approximately middle of 8th stria. Stria with coarse punctures. Intervals with small but distinct punctures. Base of elytra with an irregular row of coarse punctures each bearing a small, yellow seta.

Abdominal sternite 8 medially about as wide as sternites 3–5 combined, with slightly sinuate apical margin and with slight excavation in the middle.

Parameres with outer lobes having large circular situations lateroapically ( Fig. 36 E). Internal sac of aedeagus with somewhat fork-shaped sclerite ( Fig. 36 F).

Female. Females ( Fig. 36 C) can be separated from males by having apical protibial spur; relatively smaller pronotum; minute tubercle in the middle of frontoclypeus; wider abdominal sternite 8, which is not sinuated apically; and scutellum more angulate apically.

Variation. Body length of examined specimens varied from 6.2–6.5 mm (males) and from 5.9–6.5 mm (females).

Remarks. Benderitter (1914a) described T. modestus from two males and four females from “Mianinarévo” (misspelling of Miarinarivo). Paulian (1977) was unaware of the depository of these specimens. However, we found the complete type series at the MNHN. For the purpose of the stability of the nomenclature, one of the male specimens ( Figs. 36 A–B) is here designated the lectotype.

Distribution. This species is known from two localities in the Central Plateau ( Fig. 36 H).

Figures

FIGURE 36. Triodontus modestus, lectotype male (A, B, D), paralectotype male (E, F), paralectotype female (C). Habitus in dorsal (A, C) and dorsolateral view (B), labels of lectotype (D), aedeagus in lateral view and parameres in dorsal and ventral view (E), internal sac of aedeagus (F), abdomen (G), distributional records (H).