Two new species of Formicoxenus Mayr 1855 and Leptothorax Mayr 1855 from Tibet (Hymenoptera: Formicidae)

Abstract

The Palaearctic species of the socially parasitic ant genus Formicoxenus Mayr 1855 are taxonomically revised. A numeric analysis of phenotypical characters in workers showed a close relatedness of the three Palaearctic Formicoxenus species and a strong separation from the six independent Palaearctic species of the genus Leptothorax Mayr 1855. Myrmica laeviuscula Foerster 1850, Myrmica lucidula F. Smith 1858 and Formicoxenus nitidulus var. picea Wasmann 1906 are synonymized with Formicoxenus nitidulus (Nylander 1846) whereas Formicoxenus orientalis Dlussky 1963 and Leptothorax zhengi Zhou et Chen 2011 are established as junior synonyms of Formicoxenus sibiricus (Forel 1899). The new species Formicoxenus gebaueri n.sp. is described from NE Tibet. It was found as a guest ant in a nest of an undescribed species of the ant subgenus Serviformica Forel 1913. The very plastic host selection of Palaearctic Formicoxenus species is explained by the presence of a fully functional worker caste. Leptothorax tibeticum n.sp., a species related to L. muscorum (Nylander 1846), is described from the high Tibetan Plane. A key to the workers of Formicoxenus species and independent Leptothorax species of the Palaearctic is provided and each species is depicted by z-stack images in three visual positions.

Keywords

• cryptic species
• numeric morphology-based alpha-taxonomy
• inquilines
• host specifity