Gibboryctes gracilicornis Dupuis and Dechambre 2008: 22

Costa, Leidiane O., Duarte, Paulo R. M., Iannuzzi, Luciana & Grossi, Paschoal C., 2022, Taxonomic revision and notes on natural history of the enigmatic beetle genus Gibboryctes Endrödi (Coleoptera: Melolonthidae: Dynastinae), Journal of Natural History 56 (1 - 4), pp. 191-225 : 215-216

Gibboryctes gracilicornis Dupuis and Dechambre 2008: 22 (new combination).

Type material

Heterogomphus gracilicornis Prell, 1912 , holotype not examined. Gibboryctes acuminatus Endrödi, 1978 , holotype not examined.

Non-type material

ARGENTINA: Mendoza, La Paz, December 2005 – 2 males ( BCRC) . Santiago Del Estero: Choya , El Quebrado, November 1962 – 2 males, 2 females ( BCRC); Frias, 25 January 2005, E . Abadie – 1 male ( CERPE); Pinto, December 2007, E . Abadie – 1 female ( CERPE) .

Male ( Figure 4 (a,b))

Redescription. Length: 25.7–26.3 mm. Width: 12.0– 12.4 mm. Colour: Head, pronotum, legs and venter black; elytra reddish brown. Head: Subtriangular, provided with a long, curved backward horn at middle in lateral view. Clypeus triangular, acuminate anteriorly, densely punctate, moderately setose. Horn wide at basis (covering the clypeus in dorsal view), gradually narrowing towards apex; posterior surface weakly lobed at middle in lateral view; surface moderately punctate; punctures oval, scattered about 3 diameters of punctures. Frons smooth; interocular width equals 3.3 times transverse eye diameters. Ocular cantus triangular, with acute outer corners; surface rugose, scarcely setose on outer corners. Mouthparts: Labrum transverse, subrectangular, with a fringe of bristles on apical margin ( Figure 6 (d)). Mandibles with 2 lobed teeth raised laterally to clypeus; teeth deeply separated by a V-shaped notch; subapical tooth wider compared to apical tooth; molar area striated ( Figure 7 (d)). Maxillary galea triangular, with 3 triangular, pointed teeth at inner margin (1 apical, 1 medial, 1 basal) ( Figure 8 (d)). Papomeres I– IV combined as long as maxilla in length. Labium subtriangular, slightly rounded laterally on basal half, weakly bilobed at apex; surface densely rugopunctate; punctures large, deep and coalescent; sides covered with innumerous erect bristles, disc glabrous. Antennae: Provided with 10 segments; club oval, subequal in length to anteromeres II–VII combined. Thorax: Pronotum subpentagonal in dorsal view, with sinuous lateral margins in lateral view; anterior margin with a deep, V-shaped notch at middle; posterior margin sinuous, with no border; posterior discal area with a strong, apically bifurcate horn in dorsal view ( Figure 9 (c)); horn curved frontward, wide at basis, narrowing towards apex; anterior discal surface smooth; anterolateral area strongly rugose (aureola oposita), that extends posteriorly in 2 regions (on horn basis, on posterior corners) separated by a finely punctate area; dorsal surface of horn moderately covered with shallow punctures (separated by about 3 diameter of punctures), becoming finely punctate on posterior area; posterior margin coarsely rugose. Scutellar plate parabolic, densely covered with large, deep, setigerous, irregularly scattered punctures. Elytral surface weakly covered with small, shallow, irregularly scattered punctures; sutural stria well marked; discal and lateral striae barely marked; epipleuron separated from elytral lateral edge by a deep groove on anterior area in dorsal view, becoming close posteriorly. Legs: Protarsi with sickle-shaped claws; tarsomere V clavate, as short as tarsomeres II–IV combined; tarsomeres I–IV beaker-shaped, subequal in length. Protibiae with 4 teeth on outer margins (1 apical, 2 medial, 1 basal); apical tooth curved; medial teeth slightly narrow, elongate (1.47 times longer than width). Mesotarsi with tarsomeres I–IV beaker-shaped, gradually decreasing in size. Mesotibial inner surface densely covered with long bristles; outer surface with 2 transverse (1 basal, 1 medial), crenulate carinae; apex truncated; carinae and apex covered with setae. Metatarsi similar to mesotarsi. Metatibiae wide apically compared with the mesotibiae. Abdomen: Tergite VIII transverse, strongly convex in lateral view, densely covered with setigerous punctures on sides and anteriorly; discal area glabrous. Ventrites II–V densely rugopunctate and setose on sides, weakly puncate and glabrous on disc; ventrite VI emarginate at middle of posterior margin, bordered with setae posteriorly, weakly punctate on sides, smooth on disc. Venter: Prosternal process subtriangular, glabrous. Mesoventrite completely, densely setose. Metaventrite smooth longitudinally on disc. Aedeagus: Parameres, in dorsal view, symmetrical, smooth, oval, rounded at basal half, gradually convergent towards apical half ( Figure 10 (e)). Parameres, in lateral view, shorter (1.8 times shorter than phalobasis), subtriangular, dorsoventrally wide at basal half, becoming gradually flattened towards apical half ( Figure 10 (f)), ventrally without carina.

Female ( Figure 4 (c,d))

Redescription. Length: 26.0– 26.6 mm. Width: 12.7–13.0 mm. Quite distinct from male in the following aspects: Head: Surface with a short, transverse tubercle ( Figure 11 (d)); ocular canthus wide, with rounded anterior margin. Thorax: Pronotum quadrangular, with no horn, with a weak notch at middle of anterior margin ( Figure 11 (d)); pronotal surface densely covered with large, deep, ocellate, coalescent punctures ( Figure 11 (d)); elytral surface densely punctate. Legs: Protibial dorsal surface rugose; outer teeth rounded at apex ( Figure 11 (d)). Abdomen: Tergite VIII flattened in lateral view; ventrite VI subtriangular, with complete posterior margin.

Remarks

It was not possible to access the type specimens of H. gracilicornis and G. acuminatus . For this reason, the additional specimens were identified through the descriptions, highresolution images, and information from the type labels of both species available in Dupuis and Dechambre (2008).

Geographic distribution ( Figure 14C )

Only known from Argentina (Mendoza, Santiago del Estero [new record]) .

Figures

Figure 4. Heterogomphus gracilicornis Prell, 1912. (a,b) Male habitus in dorsal and lateral views, respectively; (c,d) female habitus in dorsal and lateral views, respectively.

Figure 6. Labrum in dorsal view. (a) Gibboryctes szelenyii Endrödi; (b) Gibboryctes ebeninus sp. nov.; (c) Gibboryctes endroedii sp. nov.; (d) Heterogomphus gracilicornis Prell; (e) Tetragus waldenfelsi (Endrödi).

Figure 7. Right mandible in dorsal view. (a) Gibboryctes szelenyii Endrödi; (b) Gibboryctes ebeninus sp. nov.; (c) Gibboryctes endroedii sp. nov.; (d) Heterogomphus gracilicornis Prell; (e) Tetragus waldenfelsi (Endrödi). Red arrows indicate the apical tooth in (a–e), striate molar in (d).

Figure 8. Right maxilla in ventral view. (a) Gibboryctes szelenyii Endrödi; (b) Gibboryctes ebeninus sp. nov.; (c) Gibboryctes endroedii sp. nov.; (d) Heterogomphus gracilicornis Prell; (e) Tetragus waldenfelsi (Endrödi). Red arrows indicating triangular galea in (a), elongate maxillary palpomere II in (b), lobed inner margin of galea and stipe with triangular lobe in (c), pointed and triangular teeth on galea in (d), scythe-shape d teeth and rounded inner margin of galea in (e).

Figure 9. Detail of head, pronotum and prothoracic legs of males in dorsal view: (a) Gibboryctes szelenyii (Endrödi); (b) Gibboryctes endroedii sp. nov.; (c) Heterogomphus gracilicornis Prell; (d) Tetragus waldenfelsi (Endrödi).

Figure 10. Aedeagus with parameres in dorsal and lateral views, respectively. (a,b) Gibboryctes szelenyii Endrödi; (c,d) Gibboryctes endroedii sp. nov.; (e,f) Heterogomphus gracilicornis Prell; (g,h) Tetragus waldenfelsi (Endrödi).

Figure 11. Detail of head, pronotum and prothoracic legs of females in dorsal view: (a) Gibboryctes szelenyii Endrödi;(b) Gibboryctes ebeninus sp. nov.; (c) Gibboryctes endroedi sp.nov.; (d) Heterogomphus gracilicornis Prell; (e) Tetragus waldenfelsi (Endrödi). Arrow indicates punctate frons in (b).

Figure 14. Geographic distribution maps. (a) Tetragus species; (b) Gibboryctes species; (c) Heterogomphus gracilicornis Prell.