Comments on the chaetotaxy of the genus Orchesella (Collembola, Entomobryomorpha) with a redefinition of the 'spectabilis' group and description of a new species of Orchesella from the Caucasus
Based on the study of the chaetotaxy of 16 European species of Orchesella a system of notation of groups of macrosetae on head and body is proposed. It mostly corresponds to the system of notation by Jordana & Baquero (2005) for Entomobrya. Some groups of the latter system are not used and several new groups of setae are defined. The ‘spectabilis’ group is redefined, divided into two subgroups, and taxonomical remarks are given for O. bulgarica, O. croatica, O. flavescens, O. kervillei, O. pannonica, O. pontica, O. pulchra, O. spectabilis, O. sphagneticola and O. xerothermica. O. subnigra is synonymised with O. pulchra. The distribution and ecology of species of the ‘sphagneticola’ subgroup are presented. O. stebaevae sp. nov. is described from the Caucasus
chaetotaxy notation system, Orchesella stebaevae n.sp.