Triodontus owas Westwood 1852
Creators: name: Frolov, Andrey V.
name: Montreuil, Olivier
name: Akhmetova, Lilia A.
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Orphnidae
Triodontus
Triodontus owas

description: Triodontus owas Westwood, 1852
(Figs. 37 A–G; 38A–C)
Triodontus owas Westwood, 1852: 74; Paulian, 1937: 14, 1977: 1212. Triodontus vadoni Paulian, 1977: 1215, new synonym
Triodontus perrotorum Paulian, 1977: 1219, new synonym
Type material examined. Orphnus owas: holotype (Figs. 37 A–B), male, “Madag / Owas Westw. (Reiche) Madagasc. / Orphnus nov. sp. / Type / 67.45/ II” (BMNH).
Triodontus vadoni: holotype (Fig. 38 B), male, “Ambohitsitondrona Madagascar XII-52 Michel” (MNHN).
Triodontus perrotorum: holotype (Fig. 38 C), male, “Ste Marie de Madagascar Perrot Freres X-XII 1896 / Triodontus perrotorum n. sp. R. Paulian det. / MUSEUM PARIS 1952 COLL R OBERTUR / TYPE ” (MNHN). Paratypes: two males and two females with the same locality data as the holotype (MNHN).
Additional material examined. MADAGASCAR: Antsiranana: two males, one female, “ Amber geb. [Amber Mountains, 12°37′00″S, 49°09′00″E]” (SMTFD); Toamasina: one male, “Ambohitsitondrona Madagascar XII-52 Michel [15°34′59″S, 50°01′00″E]” (MNHN); three males, “ Madagascar Ambodivoangy I.1945 Vadon! [15°17′49″S, 49°36′47″E,]” (MNHN); one male, “ Madagascar Est Dist. Mananara - N Mont Antampona Vadon Peyrieras [Mananara District, North of Antampona Mountain, 15°58′00″S, 49°13′00″E]” (MNHN); one male, “ Madagascar Fenerive E.Perrot [17°22′00″S, 49°25′00″E]” (MNHN); one male, “ Madagascar Ambohitsitondrona I-1946 Vadon! [15°34′59″S, 50°01′00″E]” (MNHN); one male, one female, “ Madagascar Ambohitsitondrona II- 1948 Michel [15°34′59″S, 50°01′00″E]” (MNHN); one male, “ Madagascar Fampanambo [15°22′15″S, 49°37′59″E] XII” (MNHN); Fianarantsoa: one male, “ Madagascar Foret Tanala Alluaud 1901 [Tanala Forest,]” (MNHN); one male, “ Madagascar Fianarantsoa Perrot Freres 2 Semestre 1892 [21°25′59″S, 47°04′59″E]” (MNHN); one male, one female, “ Madagascar Est Ranomafana XI.2004 [Ranomafana National Park, 21°18′00″S, 47°30′00″E, XI.2004, O. Montreuil]” (OMCP); Mahajanga: three males, two females, “S te Marie de Madagascar Perrot Freres X–XII 1896 [Sainte Marie de Madagascar, near Marovoay, 16°06′00″S, 46°37′59″E]” (MNHN); Madagascar (no precise locality): three males (SMTFD); three males (IRSNB); one male (NMPC).
Differential diagnosis. From the most similar species, T. viettei new species and T. hildebrandtii, T. owas differs in having the outer lobes of the parameres relatively slender in lateral and dorsal view (Fig. 37 D).
Description. Male. Color brown to dark brown, legs, antennae, and underside of the body slightly paler (Figs. 37 A, 38A, C).
Frontoclypeus slightly convex anteriorly, rounded laterally, anterior margin crenulate and setose in dorsal view. Eyes relatively small (diameter slightly smaller than 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 adjacent to bulge, and with 2 ridge-shaped tubercles laterally of each excavation. The 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 middle, with apical border deeply sinuate medially (Fig. 37 F).
Parameres (Fig. 37 D) with outer lobes relatively slender in lateral and dorsal view, strongly sclerotized, with distinct lateral notches and teeth situated more or less apically. Internal sac of the aedeagus with 1 strongly sclerotized sclerite and 2 additional similar sclerites (Fig. 37 E).
Female. Females (Fig. 37 C) differ from males in having an apical spur on protibiae; absence of head and pronotum armature including tubercles mediad of each eye; and longer abdominal sternites including 6th sternite, which is evenly rounded apically.
Variation. Pronotal and head armature of males is subject to allometric variability from fully developed (as described above) to less developed (with the males having short frontoclypeal tubercles and small excavation on the pronotum anteriorly). Body length of examined specimens varied from 11.0–14.0 mm (males) and from 11.0– 12.0 mm (females).
Distribution. Triodontus owas is known from a few localities mostly from the eastern Madagascar: from Amber Mountain in the north to Ranomafana National Park in the south (Fig. 37 G). The localities are situated in the eastern rainfall forest ecoregion except for Marovoay, which is situated in the dry deciduous forest ecoregion in western areas of the island.
Remarks. It can be inferred from the Paulian’s (1977) work, that he did not examine the holotype of T. owas. The characters and illustrations provided suggest that the specimens he considered T. owas belonged to T. owas, T. itremoi, and T. viettei, as treated here. Figures of the parameres (Paulian 1977, Figs. 22–23) belonged to T. itremoi, as treated here, while the description of the pronotum shape corresponds rather to T. owas, T. copridoides, or T. viettei. Examination of the types of T. vadoni and T. perrotorum showed that they both have diagnostic characters of T. owas. The differences between T. vadoni and T. perrotorum are due to the allometric variability of T. owas and, therefore, two new synonymies are here proposed.
description: Published as part of Frolov, Andrey V., Montreuil, Olivier & Akhmetova, Lilia A., 2016, Review of the Madagascan Orphninae (Coleoptera: Scarabaeidae) with a revision of the genus Triodontus Westwood, pp. 1-93 in Zootaxa 4207 (1) on pages 74-76, DOI: 10.11646/zootaxa.4207.1.1, http://zenodo.org/record/200444