Ateuchus (Lobidion) punctatissimus ( Génier, 2010 )

Montoya-Molina, Santiago, González-Alvarado, Arturo, Giraldo-Echeverri, Carolina & Vaz-de-Mello, Fernando Z., 2021, Ateuchus fedescobari - a new dung beetle (Coleoptera: Scarabaeinae) species from Colombia, and redescription of the rare A. punctatissimus (Génier, 2010) from Brazil, Journal of Natural History 55 (1 - 2), pp. 115-124 : 117-119

Ateuchus (Lobidion) punctatissimus ( Génier, 2010)

( Figures 1 (a–h) and 4)

Lobidion punctatissimum Génier 2010: 46 Ateuchus (Lobidion) punctatissimus Génier & Cupello 2018: 3 [new combination]

Diagnosis

Ateuchus punctatissimus can be separated from A. fedescobari sp. nov. by the presence of a black, heavily punctate, body surface ( Figure 1 (a,c)), and sixth ventrite with a single acute dentiform process pointing posteriorly ( Figure 1 (b,d)).

Redescription

Male. Dorsal and ventral surface black, shiny. Length: 8 mm. Head subtriangular, unarmed. Surface heavily punctate, punctation separated by twice the diameter of a puncture; surface of disc and basal third heavily microsculptured; apical third punctuation rugose ( Figure 1 (a,c)). Pronotum gibbous, wider than long. Pronotal disc shiny and smooth, with deep microsculptured punctures separated by once the diameter of a puncture; pronotal anterior angle obtuse and directed towards front, medial angle protruded. Margin between anterior and medial angles curved. Anterior and lateral margins shiny and not punctate, margination absent posteriorly ( Figure 1 (a)). Hypomeral surface finely microsculptured, glabrous; hypomeral carina complete, joining medial and external margins. Metasternal disc covered by microsculpture and simple well-impressed punctures; lateral edges covered by rugose sculpture ( Figure 1 (b)). Abdomen sixth ventrite widest, with acute dentiform process directed posteriorly ( Figure 1 (b)). Elytra interstriae smooth, with fine randomly separated punctures. Striae strongly marked, punctures wider than striae, punctures separated by twice the diameter of a puncture on elytral disc. Seventh stria not reaching the elytral base, eighth and ninth striae punctures widest, resembling rugosity on apical portion. Elytral epipleuron explanate viewed laterally, with irregular transverse rugulae ( Figure 1 (a,d)). Legs anterior edges of profemora and posterior edges of mesofemora and metafemora coarsely microsculptured. Protibial spur flattened. Pygidium surface covered by large microsculptured punctation, apical edge truncate.

Aedeagus parameres subtriangular and symmetric, basal edge straight. Phallobase twice as long as parameres ( Figure 1 (e,f)). Other characters of aedeagus and endophallus as represented in Figure 1 (g,h).

Sexual dimorphism

Females differ from males as follows: Length: 7.5 mm. Head triangularly shaped. Cephalic carina horizontally arcuate in dorsal view, clypeus feebly emarginated and upturned medially. Pronotum noticeably more gibbous than in males. Pronotal medial angle rounded. Legs protibial spur spiniform.

Figures

Figure 1. Ateuchus (Lobidion) punctatissimus male. (a) habitus; (b) ventral view; (c) head frontal view; (d) elytra and pseudoepipleura lateral view; (e) aedeagus lateral view; (f) aedeagus dorsal view; (g) internal sac of the aedeagus; (h) endophallus.