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.

Figures

Figure 3. Male dorsal habitus: (a) Bothynus arriagadae sp. n.; (b) Bothynus ascanius; (c) Bothynus cribrarius; (d) Bothynus cyclops; (e) Bothynus cylindricus; (f) Bothynus deiphobus; (g) Bothynus gisae sp. n.; (h) Bothynus laevipennis; (i) Bothynus laticifex; (j) Bothynus minor; (k) Bothynus nyx; (l) Bothynus ovalatus sp. n.

Figure 7. Ventral view of left maxilla: (a) Bothynus arriagadae sp. n; (b) Bothynus ascanius; (c) Bothynus ovalatus sp. n.; (d) Bothynus sapukai sp. n. gl = galea.

Figure 10. Dorsal view of the left elytron (a–c), anterior corner of the right elytron (d–e): (a) Bothynus laevipennis; (b) Bothynus nyx Ratcliffe, 2010; (c) Bothynus thrix; (d) Bothynus arriagadae sp. n. (black arrow points to the absence of marginal epipleura); (e) Bothynus ovalatus sp. n.

Figure 13. Parameres in caudal (a–r) and frontal views (s, t): (a) Bothynus arriagadae sp. n.; (b) Bothynus ascanius; (c) Bothynus cribrarius; (d) Bothynus cyclops; (e, s) Bothynus cylindricus (arrows point to basal constriction); (f) Bothynus deiphobus; (g) Bothynus gisae sp. n.; (h) Bothynus laevipennis; (i, t) Bothynus laticifex; (j) Bothynus minor; (k) Bothynus nyx; (l) Bothynus ovalatus sp. n. (arrows point to contiguous basis of the apical lobes); (m) Bothynus robustus sp. n.; (n) Bothynus rufipennis sp. n.; (o) Bothynus sapukai sp. n. (arrows point to the basal separation of the apical lobe); (p) Bothynus scutellopunctatus sp. n.; (q) Bothynus fabius; (r) Bothynus thrix. al = apical lobe.

Figure 14. Parameres in lateral view: (a) Bothynus arriagadae sp. n.; (b) Bothynus ascanius; (c) Bothynus cribrarius; (d) Bothynus cyclops; (e) Bothynus cylindricus; (f) Bothynus deiphobus; (g) Bothynus gisae sp. n.; (h)Bothynus laevipennis;(i)Bothynus laticifex;(j) Bothynusminor; (k)Bothynus nyx;(l)Bothynus ovalatus sp.n.; (m) Bothynus robustus sp. n.; (n) Bothynus rufipennis sp. n.; (o) Bothynus sapukai sp. n.; (p) Bothynus scutellopunctatus sp. n.; (q) Bothynus fabius; (r) Bothynus thrix.

Figure 15. Female dorsal habitus: (a) Bothynus arriagadae sp. n.; (b) Bothynus ascanius; (c) Bothynus bentoi sp. n.; (d) Bothynus cribrarius; (e) Bothynus cyclops; (f) Bothynus cylindricus; (g) Bothynus deiphobus; (h) Bothynus gisae sp. n.; (i) Bothynus laevipennis; (j) Bothynus laticifex; (k) Bothynus minor; (l) Bothynus Moroni sp. n.

Figure 22. Known geographical distribution of Bothynus arriagadae sp. n., Bothynus cylindricus, Bothynus laticifex, Bothynus ovalatus sp. n., Bothynus rufipennis sp. n., and Bothynus sapukai sp. n.