The dung beetle tribe [taxon-name: Deltochilini] Lacordaire, 1856 (= [taxon-name: Canthonini] Lansberge, 1874, synonymy according to ^{Bouchard et al. (2011)}), displays a Gondwanian distribution and is the most genus-rich tribe of the [taxon-name: Scarabaeinae]. It comprises 873 species grouped into 91 genera that constitute 40% of the entire generic diversity of the subfamily [taxon-name: Scarabaeinae] (^{Davis et al. 2008}). However, the monophyly of the tribe is doubtful according to a revision of African genera (^{Scholtz and Howden 1987}), and it appears polyphyletic in the morphology-based and molecular phylogenies (^{Philips et al. 2004}; ^{Ocampo and Hawks 2006}; ^{Monaghan et al. 2007}; ^{Sole and Scholtz 2010}). Such ambiguity highly complicates the diagnosis of the tribe and thus makes a consensus about its generic composition impossible at the moment.

The Oriental genus [taxon-name: Parachorius] Harold, 1873 comprises six species and, according to the last monographic study (^{Balthasar 1963}), belongs to the tribe [taxon-name: Pinotini] Kolbe, 1905, which is a synonym of the [taxon-name: Ateuchini] Laporte, 1840 (^{Smith 2006}; ^{Bouchard et al. 2011}). ^{Vaz-de-Mello (2007}; ²⁰⁰⁸) places [taxon-name: Parachorius] within the tribe [taxon-name: Coprini] Leach, 1815 based on morphological phylogenetic analysis of [taxon-name: Ateuchini] and related taxa. By contrast, another preliminary morphology-based phylogeny of Oriental [taxon-name: Deltochilini] using aedeagal and somatic characters (Tarasov, unpublished) strongly suggests that [taxon-name: Canthon] Hoffmannsegg, 1817 (the most speciose genus of the [taxon-name: Deltochilini]), [taxon-name: Parachorius], and another Oriental deltochiline genus [taxon-name: Cassolus] Sharp, 1875, form a monophyletic group. Therefore, here, we treat [taxon-name: Parachorius] as a deltochiline. Based on study of external morphological characters within the tribe [taxon-name: Deltochilini], [taxon-name: Parachorius] seems to be most closely related to the genus [taxon-name: Cassolus]. The genus [taxon-name: Cassolus] includes nine species that are morphologically very heterogeneous. Such morphological variation, especially when compared with the morphology of the known species of [taxon-name: Parachorius], may indicate a nested position of the latter genus within [taxon-name: Cassolus] (Tarasov, unpublished).

Whilst surveying recent scarab collections from Laos deposited at the Naturhistorisches Museum in Basel, Switzerland (NHMB), we discovered a very interesting deltochiline species displaying a mixed character set between [taxon-name: Parachorius] and [taxon-name: Cassolus]. This species cannot be unequivocally placed in either genus using current taxonomic concepts of these taxa (^{Balthasar 1963}). However, we tentatively place this new species in the genus [taxon-name: Parachorius].

Discovery of this species supports the above mentioned evidence for the close relationship between [taxon-name: Cassolus] and [taxon-name: Parachorius] as well as our provisory placement of [taxon-name: Parachorius] within the [taxon-name: Deltochilini]. Its description, provided here, enables its incorporation in the upcoming phylogenetic analysis of the entire generic complex.

All photos were taken with a digital camera attached to a dissecting microscope (Leica MZ16A). Male aedeagi in Figs 1–3 were photographed in glycerin. First, the dissected aedeagus was macerated in 10% solution of KOH for several hours and then rinsed with distilled water. Finally, the aedeagus was placed in glycerin for taking pictures and subsequent storage.

All the material used in this study is housed in the NHMB.

We are very thankful to Alexey Solodovnikov (Natural History Museum of Denmark, Copenhagen) for his suggestions, advice and first review of the manuscript. Adrian Davis (University of Pretoria, Republic of South Africa), Jan Krikken (Nationaal Natuurhistorisch Museum, Leiden, the Netherlands), Andrey Frolov (Zoological Institute, St. Petersburg, Russia) and Daniel Whitmore (Corpo Forestale dello Stato - Centro Nazionale Biodiversità Forestale “Bosco Fontana”, Verona, Italy) are sincerely acknowledged for their suggestions and corrections that significantly helped to improve this paper. Our thanks are due to Michel Brancucci and Isabelle Zürcher (NHMB) for making material under their care available for this study. We are also grateful to Pierre Tauzin (Vanves, France) for his help in obtaining needed literature, and to Tristao Branco (Porto, Portugal) for his advice and help. This paper is completed during the stay of one of us (S.T.) as a visiting student at the Department of Entomology of the Natural History Museum of Denmark, under financial support from the grants of that department. S.T. is sincerely thankful to friendly team of the Department for their help and support.