Bothynus minor Steinheil, 1872

Duarte, Paulo R. M., Dupuis, Fabien & Grossi, Paschoal C., 2025, Taxonomic revision of the Bothynus ascanius (Kirby, 1819) (Coleoptera: Melolonthidae: Dynastinae) species group, Journal of Natural History 59 (9 - 12), pp. 663-737 : 709-711

Bothynus minor Steinheil, 1872

( Figures 2 (h), 3(j), 5(c), 13(j), 14(j), 15(k), 24)

Bothynus minor

Steinheil 1872: 561–562 (original description); Arrow 1937b: 41 (catalogue); Blackwelder 1944: 255 (checklist, distributional information); Endrödi 1969: 113 (identification key), 133–134 (redescription, lectotype designation, distributional information); Endrödi 1985: 175 (identification key, distributional information); Krajcik 2005: 38 (checklist, distributional information); Abadie et al. 2008, pl. 14 (measures, distributional information); López-García et al. 2016: 496 (checklist, distributional information).

Differential diagnosis

Bothynus minor is a quite distinct species within the ascanius group, recognised by the following characters: Small species (reaching 15 mm in length), with stocky body

( Figures 3 (j),15(k)); clypeus triangular (posterior width about 6.0 times wider than anterior) with presence of inconspicuous anterior teeth (only observed at 50× magnification) ( Figure 5 (c)); interocular width 7.2–7.6 times the diameter of eye; teeth of mandible lobed ( Figure 5 (c)); apical lobes of parameres with a weak constriction on the base of lobes in caudal view ( Figure 13 (j)).

Type material

Lectotype male, labelled: (a) ‘Patagones’ [handwritten]; (b) ‘minor /Steinh’ [handwritten]; (c) ‘ExMusaeo/E.Steinheil’ [inscribed within a black border rectangle]; (d) ‘MUSÉUM PARIS/ 1952/coll. R. OBERTHÜR’ [label bordered in black]; (e) ‘ Lectotypus / Bothynus / minor Steinh. / Endrödi’ [label bordered in red, partly handwritten]; (f) ‘MNHN/EC7109’ [label bordered in black] ( MNHN) ( Figure 2 (h)).

Additional material

ARGENTINA: Buenos Aires: Cañuelas , 15 .xi .2010, P . Wagner leg . – 1 male ( EPGC); Ezeiza , xi .2018 . – 1 male, 1 female ( FDPC) . Patagonia: Rio Negro , 1897, de sept, H . de Vaulx – 1 male ( MNHN); Rio Negro to Rio Teca , ix .1980 . – 1 male, 1 female ( FDPC) .

Male redescription ( Figure 3 (j))

Length: 14.1–15.0 mm. Width: 8.0– 8.5 mm. Colour: Reddish brown. Head: Clypeus triangular (posterior width about 6.0 times wider than anterior), strongly convergent; anterior teeth small (only observed under high magnification: 50×); surface glabrous, slightly rugose in a longitudinal area at middle, sides weakly punctate ( Figure 5 (c)). Frontoclypeal carina weakly marked, raised in lateral view. Frons scarcely setose, coarsely rugopunctate. Interocular width about 7.2–7.6 transverse eye diameters. Mouthparts: Mandible with lobed, nearly fused teeth ( Figure 5 (c)). Maxilla with rounded apex, with no tooth. Labium subtriangular, broadly concave, surrounded with long setae, discal setae shorter than lateral. Antennae: Club globular, subequal in length to antennomeres 2–7 combined. Prothorax: Pronotum with strong, conical anterior tubercle; cavity deep, rounded, wide (occupying over 1/2 of pronotal anterior area), usually extending to posterior area of pronotum, sometimes bearing a weak tubercle on each side; anterior corners of pronotum with large, deep, dense punctures, from contiguous to coalescent; sides close to lateral margins with deep, large punctures (from contiguous to about 2 puncture diameters apart), becoming shallow, sparser, smaller towards disc; punctures on disc minute; cavity bearing large, C-shaped, coalescent punctures; lateral margins close to posterior corners sometimes with scarce setae. Pterothorax: Elytra bearing well-marked striae; each stria covered with ocellated, shallow, small punctures, spaced over 3 puncture diameters; interstriae mostly covered with minute punctures. Legs: Inner protarsal claw simple, similar to outer claw. Meso- and metatibia only with a middle carina diagonally produced on outer surface. Meso- and metatarsomeres 2–4 provided with long setae (longer in size compared to subsequent tarsomere) arranged on apex. Abdomen: Tergite 7 with stridulatory apparatus confined to discal area, formed by 1 band of transverse, finely marked, paired striae. Tergite 8 densely rugopunctate on sides; discal area weakly punctate, glabrous; scarce setae confined on sides. Aedeagus: Parameres, in dorsal view, rounded laterally at basal half, strongly constricted lateroventrally towards to apical half, bearing 2 oval lobes on apex; lobes slightly constricted at basis ( Figure 13 (j)). Parameres, in lateral view, strongly concave at middle, ventrally without ventrobasal carina ( Figure 14 (j)).

Female description ( Figure 15 (k))

Length: 13.8–14.0 mm. Width: 7.6–8.0 mm. As for the male, except in the following aspects: Colour: Nearly entirely reddish brown, except for the head, pronotum and protibial margins dark. Prothorax: Pronotum bearing a small anterior tubercle; cavity oval, narrow, occupying 1/3 of pronotal area; surface nearly completely covered by large, deep, dense, contiguous punctures. Abdomen: Tergite 8 entirely setose. Sternite 8 weakly rugose, entirely setose.

Distribution

Known from Argentina (Buenos Aires, Patagonia) ( Figure 24). Recently, Ratcliffe et al. (2023) expanded the known distribution of B. minor in Argentina. Bothynus minor has the most meridional distribution within the B. ascanius group.

Remarks

The configuration of parameres of B. minor is similar to those found in most species of the ascanius group, but is unique in the presence of a lateral constriction in the apical lobes of parameres in combination with the absence of a ventrobasal carina.