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

Abstract

Eighteen new species of the genus Orchestina are described on the basis of specimens obtained from fogging samples inthe 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. mi-crofoliata, O. probosciformis and O. saaristoi. Excepted for O. intricata, they are all known from males and females, al-though those of O. debakkeri and O. probosciformis cannot be separated. One species (O. crypta) was recognized afterDNA-analysis and was found to show morphological differences with O. communis. The study revealed a series of re-markable sexually dimorphic characters most of which had not been documented so far: modified leaf shaped setae on thelabium in some species arranged asymmetrically, endites with hook shaped excrescences and rows of spectacular flattenedsetae, remarkable cheliceral setae and outgrowths, a modified clypeus, modified front legs, a preocular carapace swellingand the infra-ocular gutter. Spectacular modifications of the endites were already known from other Oonopidae. The function of the modifications is discussed.