Bothynus ascanius
Creators: name: Duarte, Paulo R. M.
name: Dupuis, Fabien
name: Grossi, Paschoal C.
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Scarabaeidae
Bothynus
Bothynus ascanius

description: Bothynus ascanius species group composition
Bothynus arriagadae sp. n.; Bothynus ascanius (Kirby 1819); Bothynus bentoi sp. n.; Bothynus cribrarius (Fairmaire, 1878); Bothynus cyclops (Burmeister, 1847); Bothynus cylindricus Arrow, 1937; Bothynus deiphobus (Burmeister, 1847); Bothynus fabius (Fairmaire, 1878) (revalidated name); Bothynus gisae sp. n.; Bothynus laevipennis Arrow, 1937; Bothynus laticifex Burmeister, 1847; Bothynus minor Steinheil, 1872; Bothynus moroni sp. n.; Bothynus nyx Ratcliffe, 2010; Bothynus ovalatus sp. n.; Bothynus robustus sp. n.; Bothynus rufipennis sp. n.; Bothynus sapukai sp. n.; Bothynus sartorei Ratcliffe and Cave, 2024; Bothynus scutellopunctatus sp. n.; and Bothynus thrix Hardy, 2017.
Diagnosis
The B. ascanius group comprises 21 species within the genus Bothynus that share three diagnostic characters: frontoclypeal region bearing a transverse, raised, incomplete carina, which does not reach the lateral margins of the head (Figure 1 (a)); ocular canthus with setae confined to ventral area, arranged in a transverse fringe (Figure 1 (a)); tergite 8 of females without internal plate (Figure 1 (b)). Other Bothynus species not belonging to this group possess 1–2 tubercles on the frontoclypeal region or a transverse and complete carina that reaches the lateral margins of the head; both dorsal and ventral areas of the ocular canthus bear setae, or the setae are confined to the dorsal area; tergite 8 of females is provided with an internal plate.
Description
Colour: Usually reddish to reddish brown, rarely dark brown. Head: Clypeus shape subtrapezoidal to subtriangular, uniformly convergent or sinuous laterally (with apparent constriction in anterior half); anterior margin bearing 2 raised, conical, subtriangular or lobed (flattened anteroposteriorly) teeth; dorsal surface usually rugopunctate and glabrous to scarcely setose; clypeus surrounded by dense setae projecting from ventral surface. Frontoclypeal region bearing a transverse, incomplete, raised carina, not reaching the lateral margins of head. Frons transversely rugose or coarsely rugopunctate, usually with scarce setae on sides, rarely glabrous. Ocular canthus transverse, subrectangular, glabrous dorsally, ventrally bearing a transverse fringe of setae. Mouthparts: Mandibles each bearing 3 teeth produced at outer margins; teeth usually subtriangular, rarely lobed. Maxilla with 3–5 apical teeth produced at inner margin of galea; teeth pointed. Labium subtriangular, flattened, surrounded by dense, deep, coalescent, setigerous punctures on sides; disc with weak, shallow, small punctures; discal setae scarce, smaller than those at sides. Antennae: 10-segmented; lamellae usually flattened; club from subequal to nearly 2.5 times longer than antennomeres 2–7 combined. Prothorax: Pronotum, in dorsal view, bearing a tubercle contiguous with middle of anterior margin; anterior area with a shallow to deep and small to large cavity that is rounded or oval in shape, sometimes extended to posterior pronotal area; cavity transversely rugose, densely rugopunctate or densely punctate; pronotal sides usually with large, dense, deep, ocellated punctures; punctures on posterior disc smaller, weak compared to those on sides; posterior margin mostly rugopunctate or strongly rugose. Pronotum, in lateral view, with declivous anterior area, posterior area strongly convex. Prosternal process columnar, cylindrical, projecting between coxae, apex oval. Pterothorax: Scutellar plate mostly subtriangular, usually smooth, rarely with dense punctures. Elytral surface rarely smooth or setose; usually covered with ocellate and deep punctures, small to large in size; striae mostly well impressed. Epipleurae weakly produced, usually hidden below lateral margin of elytra in dorsal view. Meso- and metaventrite from moderately to densely setose; metaventrite from glabrous to weakly setose on disc. Abdomen: Tergite 7 bearing disc with 1–2 paired bands of finely marked, transverse, stridulatory striae. Tergite 8 transverse, subtriangular, from rugose to densely punctate, glabrous to densely setose. Sternites 4–7 rugose on sides, punctate on disc; sternite 8 emarginate at middle of posterior margin. Legs: Inner protarsal claw strongly curved, simple (equal in length and shape to outer claw), deeply incised or bearing only a ventromedial process. Protarsomere 5 subequal in length to protarsomeres 3–4 combined; ventroapical area of protarsomere 5 usually with a small, triangular, projected process. Protarsomeres 2–4 subequal in length. Protibia with 3 triangular teeth produced at outer margin; basal tooth smaller to medial and apical ones; dorsal surface rugose along a longitudinal area close to base of teeth. Mesotarsomere 5 subequal in length to tarsomeres 3–4 combined; mesotarsomeres 1–4 gradually and sequentially decreasing in size. Mesotibia with sinuous apex; outer surface usually provisioned with 2 carinae (1 basal, 1 medial); medial carina obliquely produced; surface area between apex and medial carinae strongly concave; basal carina short, transverse, sometimes absent; apex and carinae bordered with spinule-like setae. Metatarsi similar to mesotarsi. Metatibia longer, robust compared to mesotibia; apex truncated; similar to mesotibiae in other aspects. Aedeagus: Phalobasis nearly 1.5 times longer than parameres. Parameres, in caudal view, oval, long (1.5 times longer than wide), rounded laterally in basal half; apical half constricted lateroventrally; apex usually with 2 oval lobes produced laterodorsally; surface usually smooth, rarely punctate. Parameres, in lateral view, arched dorsally, usually with a visible ventrobasal carina, apex usually rounded, rarely acuminate.
Sexual dimorphism
Sexual dimorphism is variable within the B. ascanius species group. Females either bearing a small pronotal tubercle or lacking one; pronotal cavity usually shallow or declivous, rarely large and deep; pronotum weakly convex posteriorly in lateral view; pronotal surface nearly entirely covered by dense, large punctures; inner protarsal claw simple, equal in length to outer claw; tergite 8 flattened or weakly convex in lateral view; sternite 8 from parabolic to subtriangular, with entire posterior margin, lacking emargination, as in the male.
Remarks
Bothynus sartorei was recently described by Ratcliffe and Cave (2024) during completion of this revision and, for this reason, is not treated here.
Distribution
The B. ascanius species group is restricted to South America, where it has a mostly meridional distribution (Figures 21–24).
description: Published as part of Duarte, Paulo R. M., Dupuis, Fabien & Grossi, Paschoal C., 2025, Taxonomic revision of the Bothynus ascanius (Kirby, 1819) (Coleoptera: Melolonthidae: Dynastinae) species group, pp. 663-737 in Journal of Natural History 59 (9 - 12) on pages 666-669, DOI: 10.1080/00222933.2025.2456579, http://zenodo.org/record/14971553