An overview of Afrotropical canopy-dwelling Orchestina (Araneae, Oonopidae),with a wealth of remarkable sexual dimorphic characters

Eighteen new species of the genus Orchestina are described on the basis of specimens obtained from fogging samples in the Afrotropical region. They are O. acaciae, O. ampulla, O. clavigera, O. communis, O. cornuta, O. crypta, O. debakkeri,O. fannesi, O. fractipes, O. gibbotibialis, O. gigabulbus, O. intricata, O. kasuku, O. lanceolata, O. macrofoliata, O. microfoliata, O. probosciformis and O. saaristoi. Excepted for O. intricata, they are all known from males and females, although those of O. debakkeri and O. probosciformis cannot be separated. One species (O. crypta) was recognized after DNA-analysis and was found to show morphological differences with O. communis. The study revealed a series of remarkable sexually dimorphic characters most of which had not been documented so far: modified leaf shaped setae on the labium in some species arranged asymmetrically, endites with hook shaped excrescences and rows of spectacular flattened setae, remarkable cheliceral setae and outgrowths, a modified clypeus, modified front legs, a preocular carapace swelling and the infra-ocular gutter. Spectacular modifications of the endites were already known from other Oonopidae. The function of the modifications is discussed