Hornosus, Dellacasa & Dellacasa & Gordon, 2015

Dellacasa, Marco, Dellacasa, Giovanni & Gordon, Robert D., 2015, A new genus for Drepanocanthoides larreae (Horn, 1887) and description of a new congeneric Mexican species (Coleoptera: Scarabaeidae: Aphodiinae), Insecta Mundi 2015 (407), pp. 1-6 : 1-2

Genus Hornosus new genus

Hornosus Gordon and Godwin, [1997] in litteris

Type species. Aphodius larreae Horn, 1887 , here designated.

Description. Small species (length 4.0–5.0 mm), oblong, convex, head and pronotum shiny, elytra alutaceous, pubescent laterally and preapically. Entirely yellowish-testaceous or head and pronotum blackish, elytra pale brownish with a piceous discal stripe. Head with epistome feebly gibbous, almost evenly moderately punctured; clypeus deeply sinuate in middle, lobate on either side; lobes produced and curved upward, strongly so in males, thinly bordered, edge glabrous; genae obtusely round, ciliate, not protruding from eyes; frontal suture unarmed, without tubercles. Pronotum transverse, evenly punctured; sides thinly bordered, edge elongately ciliate; base very finely bordered. Scutellum small, triangular, unevenly punctured. Elytra elongate, finely striate; striae crenulate; interstices almost flat, microreticulate, finely punctured, pubescent laterally and on preapical declivity; epipleura almost entirely ciliate. Foretibiae distally tridentate and proximally not serrulate at outer margin; upper side impunctate. Pygidium shiny, glabrous, superficially sparsely unevenly punctured, apical margin with few sparse and rather elongate setae. Hind tibiae with rather feeble transverse carinae on outer face; apically fimbriate, with spinules elongate and irregularly unequal. Sexual dimorphism shown in males mainly by foretibial spur cultrate and clypeus more deeply sinuate and more strongly lobate. Aedeagus with slender, elongate and not membranous paramera, apically with ventral projection. Epipharynx transverse, strongly round on sides, sinuate and elongately ciliate on anterior margin; epitorma ogival; corypha not protruding from front margin, with apical clump of rather stout celtes, nearly equal in length; pedia densely pubescent toward corypha, with few long spines more or less serially arranged; chaetopariae moderately dense and moderately elongate.

Distribution. Nearctic and Neotropical regions.

Etymology. Named in honour of George Horn, eminent American nineteenth century authority on Aphodiinae. The gender is masculine.

Discussion. The diagnostic characters of Hornosus , new genus, are:

– scutellum small, triangular;

– clypeal margin deeply sinuate in middle, lobate on either side; lobes distinctly produced and curved upward, more strongly so in males;

– pronotum not flattened at sides, with basal margin thinly bordered;

– males foretibiae angularly sinuate on inner margin;

– hind tibiae apically fimbriate, with spinules elongate and irregularly unequal.

The new genus seems not to be closely allied to other genera of Aphodiini; the peculiar shape of the clypeus is similar to that of the South African Didactyliini genus Coptochirus Harold, 1859 . In the key to genera of Aphodiini by Gordon and Skelley (2007), Hornosus could fall behind the couplet 62 as follow:

62a.

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Male clypeus with strong anterior projection on each side of middle. Length 4.0–5.0 mm. U.S.A. and Mexico............................................................................................. Hornosus new genus

Male clypeus without anterior projection on each side of middle. Length 5.0–6.0 mm. Canada and U.S.A...................................................................... Drepanocanthoides Schmidt, 1913