Cnemargulus Semenov, 1903

Ziani, Stefano, 2019, A revision of the Aphodiini genus Cnemargulus Semenov, 1903 (Coleoptera: Scarabaeoidea: Scarabaeidae), Insecta Mundi 2019 (689), pp. 1-10 : 1-3

Cnemargulus Semenov, 1903

Cnemargulus Semenov 1903: 354 ; Jacobson 1906: 315; Schmidt 1910a: 13 (as junior synonym of the genus Cnemisus ); Schmidt 1910b: 4 (as junior synonym of Cnemisus ); Schmidt 1922: 344 (as junior synonym of Cnemisus ); Semenov and Medvedev 1927: 183; Winkler 1929: 1059 (as junior synonym of Cnemisus ); Balthasar 1964: 471 (as subgenus of Cnemisus ); Medvedev and Nikritin 1971: 1881; Nikolajev 1979: 41 (as junior synonym of the Aphodius subgenus Mendidius ); Pittino 1984: 306; Nikolajev 1987: 121 (as junior synonym of the Aphodius subgenus Mendidius ); Dellacasa 1988: 401; Dellacasa 1990: 22; Dellacasa 1994: 39; Dellacasa et al. 2001: 119; Dellacasa and Dellacasa 2006: 140; Krajcik 2012: 75; Dellacasa et al. 2016: 121.

Type species. Cnemargulus krulikovskyi Semenov, 1903 (subsequent designation by Nikolajev 1979).

Diagnosis. Aphodiini species with small to medium adult body size (3.2–7.6 mm), oval-elongate, convex, glossy, glabrous dorsally. Yellow to light brown.

Head with epistome gibbous and granulate, clypeus quadridentate and distinctly bristled, frontal suture trituberculate, not reaching the genal sutures, genae auriculate, elongately ciliate, protruding from eyes.

Pronotum transverse, bordered in all the sides, sometimes the border more or less interrupted anteriorly at middle but therein irregularly crenulated by coarse punctures, rather regularly punctured on disc.

Scutellum small, triangular.

Elytra with striae fine, interstriae from nearly flat to slightly convex on disc; humeri not denticulate.

Metathoracic wings normally developed in both sexes.

Metasternal plate with complete midline furrow.

Foretibae with four or more external teeth; apical edge of mesotibiae with spinules more or less equal and a single very long seta near outer angle, almost as long as the first tarsal segment; metatibiae feebly widened apically, with upper apical spur longer than the first tarsal segment.

Pygidium with apical margin very elongately ciliate.

Secondary sexual characters very weak: foretibial and upper metatibial spur very slightly sinuate in males, normally shaped in females. Furthermore, females have elytra slightly widened in apical half.

Aedeagus with paramera elongate and more or less acuminate apically.

Epipharynx round laterally, front edge very slightly sinuate; epitorma globose; corypha with celtes more or less elongate; pedia with few spinules usually uniserially arranged, pariae with elongate spiculae.

Distribution. Only three species hitherto known, from Arabian Peninsula and Central Asia ( Dellacasa et al. 2016). The genus is new to Iran.

Natural history. Almost nothing is known about the ethology and bionomy of species belonging to the genus, other than that they live in sandy areas. As far as I know, there are no literature references in which specimens have been reported as collected in dung, as happens to the majority of the other Aphodiinae species. All the Iranian specimens referenced in this paper have come to light. This could suggest, as a hypothesis, a saprophilous habit, as for other psammophilous Scarabaeoidea attracted to light, even if the morphology of their epipharynx is clearly adapted to coprophagy ( Dellacasa et al. 2001). On the back of the first label of the lectotype of C. krulikovskyi , the handwritten note “пеСКИ, в КОрНЯХ” [sands, in roots] could confirm their root-eating habits.

The labels of two specimens of C. krulikovskyi ( Turkmenistan, “Merv”) have the handwritten note “муравейНИК” [anthill]. If confirmed, this information would suggest an intriguing relationship of the species with nests of ants, even if it should be explained much more in detail.

Discussion. Semenov (1903) described Cnemargulus and compared it with the genus Ahermes Reitter, 1891 , actually considered a junior synonym of Cnemisus Motschulsky, 1868 . Seven years later, Schmidt (1910 a, 1910b) deemed Cnemargulus a junior synonym of Cnemisus . Synonymy was confirmed by Schmidt (1922) and Winkler (1929). From then on, Cnemargulus was considered either a subgenus of Cnemisus ( Balthasar 1964) or a junior synonym of the subgenus Mendidius Harold, 1868 ( Nikolajev 1979, 1987). Medvedev and Nikritin (1971) and Pittino (1984), all authors who dealt with the topic, have considered Cnemargulus a good and distinct genus. Dellacasa (1994) provided a key to a poorly defined “mendidiform” genus-group taxon, distinguishing Cnemargulus from Cnemisus by the claws: corneous in the former, hair shaped in the latter. In addition to this character, which is not always significant, the species ascribable to the genus Cnemisus are more convex, have the head with a very distinct long frontal suture, almost reaching the eyes at sides, the pronotum not bordered anteriorly, and the femora, particularly the hindfemora, strongly widened apically. Furthermore, the Cnemisus are on average larger (7–10 mm), and their mesotibial apical spinules are equal, whereas Cnemargulus species have the mesotibiae with one exceptionally elongate apical seta, beyond the usual ones.

Cnemargulus can also be easily distinguished from Mendidius by the quadridentate clypeus—biden-tate in Mendidius —and the more transverse pronotum. Furthermore, males of the two genera can be distinguished by the metatibiae, which are wider apically and clearly longer than the metatarsi, and the paramera, which are obviously wider apically in Mendidius .