A revision of the assassin spiders of the Eriauchenius gracilicollis group, a clade of spiders endemic to Madagascar (Araneae: Archaeidae)

Abstract

An endemic group of Malagasy spiders (Araneae: Archaeidae: Eriauchenius) called the gracilicollis group is revised. The monophyly and phylogenetic relationships of the gracilicollis group are tested based on morphological characters. Archaeid spiders of Madagascar have evolved varying degrees of elongation in the cephalic area. Historically, it was believed that the extremely elongated cephalic area had evolved only once. These morphological data support the monophyly of the gracilicollis group and suggest that the elongated cephalic area has evolved more than once. All 14 species from the gracilicollis group are described and keyed, of which nine are new species: Eriauchenius ambre sp. nov., Eriauchenius anabohazo sp. nov., Eriauchenius borimontsina sp. nov., Eriauchenius griswoldi sp. nov., Eriauchenius halambohitra sp. nov., Eriauchenius lavatenda sp. nov., Eriauchenius namoroka sp. nov., Eriauchenius spiceri sp. nov. and Eriauchenius voronakely sp. nov. The morphology of the gracilicollis group is examined in detail and figures of the male and female genitalia are presented. The distributions of the gracilicollis group species are presented and discussed and higher species group relationships within the Archaeidae are discussed. © 2008 The Linnean Society of London.