Triodontus hildebrandtii ( Fairmaire, 1883 )

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 : 78-80

Triodontus hildebrandtii ( Fairmaire, 1883)

( Figs. 40 A–E)

Orphnus hildebrandtii Fairmaire, 1883: 365, 1884: 131 . Orphnus hildebrandti: Arrow 1912: 29 .

Triodontus hildebrandti: Paulian 1937: 142, 1977: 1213 .

Type material examined. Holotype ( Figs. 40 A–E), male, “MUSÉUM PARIS 1906 Coll. Leon FAIRMAIRE / Orphnus Hildebrandti Waterh / 434” (MNHN).

Additional material examined. Two males, “ Madagascar ” ( IRSNB).

Diagnosis. Triodontus hildebrandtii is most similar to T. viettei but differs from it in having outer lobes of parameres with wide lateral notches, as opposed to having slit-shaped lateral notches in T. viettei .

Description. Male. Body length 15.0 mm. Color uniformly dark brown, legs, antennae, and underside of the body slightly paler ( Figs. 40 A–B).

Frontoclypeus slightly convex anteriorly, rounded laterally, anterior margin crenulate and setose in dorsal view. Eyes relatively small (diameter slightly smaller than the distance between eye and gula in ventral view), incompletely divided by canthus into small, dorsal and large, ventral parts. Frontoclypeus with tubercles mediad of each eye and with long horn in the center of the frontoclypeus. The horn is longer than width of the head, acutely rounded apically, somewhat curved caudally, slightly rugose on posterior side.

Pronotum with a bulge medially, with large excavations each side of bulge, and with 2 ridge-shaped tubercles laterally of each excavation. Median bulge is rounded and somewhat depressed on top, with 2 distinct tubercles and a depression, receiving frontoclypeal horn. Lateral margins with wide border appearing somewhat crenulate (in dorsal view), with a row of brown setae. Anterior margin with wide, smooth border. Posterior margin with fine border; not crenulate; punctate with small, narrow, longitudinal punctures. Surface of most pronotum almost smooth, with minute, feebly-visible punctation.

Scutellum rounded apically, visible part is about 1/13 length of elytra.

Elytra convex, with distinct humeral humps. Maximum width approximately at basal 1/3. Elytra with 10 feebly visible striae on disc and with oblique line from base of 6th stria to approximately middle of 8th stria. Stria with small punctures. Intervals with sparse, minute punctures, almost smooth. Base of elytra with an irregular row of coarse punctures each bearing a small, yellow seta.

Sternite 8 medially as wide as sternites 2–5 combined, without tubercle or concavity in the middle, with apical border deeply sinuate medially.

Parameres with outer lobes being relatively wide (in dorsal view) and having slit-shaped lateral notches ( Fig. 40 E). Internal sac of aedeagus with 1 strongly sclerotized sclerite and 2 additional smaller sclerites ( Fig. 40 C).

Female. Unknown.

Variation. The non-type specimens differ from the holotype in slightly less-developed frontoclypeal and pronotal armature. Body length varies from 14.0– 14.5 mm.

Distribution. The distribution of this species is yet unknown since all three known specimens lack precise locality data.

Remarks. Paulian wrote that the type of T. hildebrandtii was unknown to him, but he treated it a valid species and mentioned some material from Tanala forest (collection of Alluaud ) ( Paulian 1937, 1977). There is one Triodontus specimen in the collection of MNHN, which bears the label “Forêt Tanala (coll. Alluaud)”. This specimen, in our opinion, belongs to T. owas . We think that the application of the name T. hildebrandtii to this or other specimens was unjustified.

In the collection of MNHN we found a specimen with a label “ Orphnus Hildebrandti Waterh ”. Although the label is not handwritten by Fairmaire, the specimen originated from Fairmaire’s collection and agrees with the original description of Orphnus hildebrandtii . Therefore we consider it the holotype.

Figures

FIGURE 40. Triodontus hildebrandtii, holotype male. Habitus in dorsal (A) and lateral view (B), internal sac of aedeagus (C), labels of holotype (D), aedeagus in lateral view and parameres in dorsal and ventral view (E).