Triodontus montreuili Frolov & Akhmetova, 2025

Frolov, Andrey V. & Akhmetova, Lilia A., 2025, A new species of Triodontus Westwood, 1846 (Coleoptera: Scarabaeidae: Orphninae) from northern Madagascar, Zootaxa 5728 (1), pp. 195-200 : 195-198

Triodontus montreuili Frolov & Akhmetova , sp. nov.

Figs. 1–5, 7–10, 14, 16

Type material. Holotype, male, labeled: “MADAGASCAR-EST Dist. Mananara-N Mont Antampona Vadon-Peyrieras” ( National Museum of Natural History , Paris, France).

Description. Holotype, male ( Figs. 1–3 , 8–10, 14, 16 ). Body length 18.0 mm, width of elytra 9.5 mm, width of pronotum 9.0 mm. Body strongly shiny, uniformly colored ( Figs. 1–3 ). Color of head, pronotum and elytra dark brown; legs, antennae and underside of the body brown.

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 frontoclypeus. The horn is longer than width of the head, acutely rounded apically, somewhat curved caudally, slightly rugose on posterior side.

Labrum bilobate, sinuate in the middle and protruding past clypeus. Length in the middle is 1/6 width (in dorsal view). Mandibles of subequal length.

Pronotum with a bulge medially, with large excavations at each side of bulge, and with 2 ridge-shaped tubercles laterally of each excavation. The median bulge is rounded and somewhat depressed on the 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, its 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 stria 6 to approximately middle of stria 8. 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.

Wings fully developed.

Fore tibiae of typical shape of Triodontus , with 3 outer teeth, not crenulated basad of the teeth. Apices with 3 robust, spur-like setae and a few small ones. Fore tarsi about 3/4 length of protibiae. Claws 1/3 length of apical tarsal segment. Apical segment of fore tarsus as long as segments 3 and 4 combined, slightly more slender than other segments. Ventral surface of fore tibiae with a longitudinal keel.

Middle and hind legs similar in shape; hind femora and tibiae slightly longer than middle ones. Tibiae somewhat triangular, with two apical spurs, with inner margin only slightly concave. Longer tibial spur slightly shorter than two basal segments of tarsus. Claws about 1/3 length of last tarsal segment. Ventral sides of femora almost impunctate, with sparse long setae.

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

Pygidium transverse, irregularly punctate and setose, mostly hidden under elytra.

Aedeagus. Phallobase 1.6 times longer than parameres, strongly sclerotized dorsally and with thin membrane ventrally ( Fig. 10 ). Parameres with outer lobes being relatively wide (in dorsal view) and having slit-shaped lateral notches ( Figs. 8, 9 ). Outer lobes of parameres with arcuate, protruding inner margin, strongly overlapping. Internal sac of the aedeagus with 1 strongly sclerotized symmetric sclerite and 2 sacciform processes covered by microspinules ( Fig. 16 ).

Female. Unknown.

Differential diagnosis. Triodontus montreuili sp. nov. is most similar to T. viettei Frolov, Montreuil & Akhmetova, 2016 . Both species have outer lobes of the parameres with slit-shaped, lateral notches ( Figs. 8, 11 ). They can be separated by different shape of the parameres: outer lobes with arcuate, protruding inner margin, strongly overlapping in T. montreuili sp. nov. ( Fig. 8 ); outer lobes are not overlapping, with non-protruding, rounded inner margin in T. viettei ( Fig. 11 ). Inner lobes of parameres are also different in these species ( Figs. 10, 13 ). Both T. montreuili sp. nov. and T. viettei can be difficult to distinguish by external morphology. The holotypes of the two species have somewhat different shape of pronotal armature. The holotype of T. viettei has the central pronotal bulge with acute tubercles anteriorly and lateral pronotal processes not connected by a keel ( Fig. 6 ), while the holotype of T. montreuili sp. nov. has the central pronotal bulge rounded anteriorly and lateral pronotal processes connected by a keel and situated closer to the anterior margin of the pronotum ( Fig. 7 ). However, the pronotal armature is only well-developed in some males and is subject to strong allometric variability. Examination of additional specimens of both species are needed for evaluation of above mentioned differences in pronotal armature.

Distribution. The species in known from the only specimen collected in Antampona Mountain, Mananara Nord district, Analanjirofo region, northern Madagascar ( Fig. 5 ).

Etymology. The new species is named after Olivier Montreuil, curator of the scarab beetle collection of the National Museum of Natural History, Paris, France.

Figures

FIGURES 1–7. Holotypes of Triodontus montreuili Frolov & Akhmetova, sp. nov. (1–5, 7) and T. viettei Frolov, Montreuil & Akhmetova, 2016 (5, 6). 1, habitus in dorsal view; 2, habitus in dorsolateral view; 3, habitus in lateral view; 4, associated labels; 5, map with localities of T. montreuili, sp. nov. (square) and T. viettei (circles); 6, 7, outline of pronotum with armature. Scale bar for figs. 1–3: 3.0 mm.

FIGURES 8–16. Male genitalia of the holotype of Triodontus montreuili Frolov & Akhmetova, sp. nov. (8–10, 14, 16) and T. viettei Frolov, Montreuil & Akhmetova, 2016 from Madagascar: Lakato (11–13, 15). 8, 11, parameres in dorsal view; 9, 12, parameres in apical view; 10, 13, parameres in ventral view; 14, 15, aedeagus in lateral view; 16, internal sac of aedeagus. Scale bar 1.0 mm.