Abstract
The monophyletic and monotypic geotrupid subfamily Lethrinae is currently classified into 11 subgenera and contains more than 130 formally described taxa on species level (species + subspecies) (cf. Bagaturov & Nikolajev 2015; Nikolajev et al. 2016; Pak & Gubin 2020; Schoolmeesters 2021).
The subgenus Scelolethrus Semenov, 1892 currently includes 26 species classified into six species groups (Král & Olexa 1996; Nikolajev 2003a, b; Bagaturov & Nikolajev 2015). Species usually have allopatric range, but rarely two to three species can occur together in one place.
Then they are mostly species from different species groups. The subgenus is widespread in Middle Asia, spliting into two geografically separated distribution areas, namely the Turkmen-Khorasan mountain system in the west (N Iran, S Turkmenistan) and the Khozratishokh range of the Hissar-Darvaz mountain system in the east (SE Uzbekistan, S Tajikistan, N Afghanistan).
One species, L. (S.) rosmarus Ballion, 1871 is extending north to the right bank of the river Syr Darya in S Kazahkstan (Nikolajev 2003a, b; Bagaturov & Nikolajev 2015; Nikolajev et al. 2016). Recent coleopterological research in northern Iran has yielded a new species of this subgenus, which can be included in the L. (S.) sulcatus Kraatz, 1883 species group sensu Nikolajev (2003b).
Members of this species group inhabit the western part of the distribution area of the subgenus Scelolethrus only. The description and differential diagnosis of this new species are presented in this paper.