Bothynus arriagadae Duarte, Dupuis and Grossi, 2025

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 : 669-671

Bothynus arriagadae Duarte, Dupuis and Grossi sp. n.

( Figures 3 (a), 7(a), 10(d), 13(a), 14(a), 15(a), 22)

Diagnosis

Bothynus arriagadae sp. n. can be separated from the other species of the B. ascanius group by the following combination of characters: Galea of mandible formed by small, serrated teeth ( Figure 7 (a)); margin of elytral epipleura indistinct in lateral view ( Figure 10 (d)); apical lobes of parameres narrow ( Figure 13 (a)).

Holotype

Male, dissected, labelled: ‘ Argentina, Provincia de San Luis, Sierras Marianas , 33°03'04'' S, 66°17'1'' W, 884 m, 15.02.2017, G. Arriagada leg’. ( CEMT).

Paratypes

Two females at CEMT with same data as the holotype .

Holotype description ( Figure 3 (a))

Length: 17.8 mm. Width: 9.1 mm. Colour: Mostly reddish brown; pro-, meso and metatibia (including their respective tarsal segments) and head darker. Head: Clypeus triangular, transverse, twice as wide as long; anterior teeth small, lobed, contiguous, separated by a poorly apparent emargination (seen under high 20× magnification); surface strongly rugose, transverse, covered with sparse, small setae. Frontoclypeal carina distinct, weakly interrupted at middle. Frons strongly rugose, rugosity concentrical; setae denser, longer than those on clypeus. Interocular width about 4.2 times transverse eye diameters. Ocular canthus transverse, subtriangular. Mouthparts: Mandible with 3 lobed teeth produced on outer margin; middle tooth wider than apical one, basal tooth smaller than apical and subapical ones. Maxillary galea with small, serrated teeth ( Figure 7 (a)). Labium subtriangular, strongly, concentrically rugose, covered with sparse setae. Antennae: Club subequal in length to antennomeres 2–7 combined. Prothorax: Pronotum, in dorsal view, with anterior tubercle small, conical; cavity subtriangular, confined to anterior disc; pronotal sides broadly rounded, surface from anterior to posterior region close to lateral margins covered with scarce, yellowish, erect setae; anterior pronotal surface with C-shaped, transverse, large, dense, coalescent punctures; posterior surface with large, dense, contiguous punctures close to lateral margins, gradually becoming sparser and smaller towards posterior disc. Pronotum, in lateral view, with declivous anterior region, posterior convex. Pterothorax: Scutellar plate triangular, transverse, about 2 times wider than long; anterior margin slightly produced towards posterior region. Elytra with 10 longitudinal striae; discal striae well marked compared to lateral ones; juxtasutural stria with small punctures, predominantly contiguous, other striae with larger and sparser punctures compared to juxtasutural ones; interstriae with irregular punctures; lateral margins with scarce, erect, yellowish setae; epipleura without defined lateral border ( Figure 10 (d)). Legs: Inner protarsal claw deeply incised, with inner branch wider and longer than outer one. Protarsomere 5 subequal in length than protarsomeres 3–4 combined, bearing a small, subapical, triangular, inner process; protarsomeres 2–4 subequals in length; protarsomere 1 two times longer than tarsomere 2. Protibia with 3 teeth produced on outer margin; apical tooth longer than other ones, basal tooth smaller than medial one. Mesotasomere 5 subequal in length to mesotarsomeres 3–4 combined; mesotarsomeres 1–4 gradually decreasing in size. Mesotibia with angularly projected apex; middle carina strongly produced, with lobed tooth on apex; basal carina absent. Metatarsomeres similar to mesotasomeres. Mesotibia with sinuate apex; broader compared to mesotibia. Metafemur broadly oval, celarly wider than mesofemur; surface with small, scarce punctures. Abdomen: Tergite 7 with stridulatory apparatus formed by a band of innumerous, transverse, complete, finely marked striae. Tergite 8 entirely covered with concentrical, strong rugosity (stronger on anterior region); anterior region transversely covered with a fringe of yellowish setae; posterior region bearing scarcer setae. Sternites 4–8 (combined) subequal in length to longitudinal midline of metaventrite; sternites 5–8 with transversely covered with yellowish, small setae (shorter in length than respective sternite); sternite 7 with an incomplete row of long setae (longer than respective sternite); sternite 8 transversely covered with long setae (longer than respective sternite) on posterior margin. Aedeagus: Parameres, in dorsal view, smooth, elongate, bearing rounded basal half, lateroventrally constricted apical half; apical lobes narrow, subparallel ( Figure 13 (a)). Parameres, in lateral view, convex dorsally, rounded apically, ventrally with a basal process, followed by a small excavation ( Figure 14 (a)).

Variation in the paratypes

Female paratypes ( Figure 15 (a)) differ from holotype in the following aspects: Length: 16.2–19.0 mm. Width: 8.4–10.0 mm. Head: Clypeus with lobed anterior margin.

Prothorax: Pronotum with oval cavity. Legs: Inner protarsal claw equal to outer claw. Protarsomere 5 without subapical process. Protibia with a rounded middle tooth. Abdomen: Tergite 8 and sternites 4–8 covered with dense setae; sternite 8 subtriangular.

Distribution

Only known from Argentina (San Luis) ( Figure 22).

Etymology

The species is named after Gerardo Arriágada, a coleopterist expert on the family Histeridae , who collected the type series.

Remarks

Bothynus arriagadae sp. n. is unique within the B. ascanius species group in having the elytral epipleura with no distinct margin.