Systematics of the “Giant” Ricinulei (Ricinoididae: Ricinoides) of West Africa, with Descriptions of Five New Species and Comparative Morphology of the Male Copulatory Apparatus

Abstract

The Ricinulei Thorell, 1876, or “hooded tick-spiders,” are among the rarest and least studied arachnid orders. RicinoidesEwing, 1929, the only Old World genus of extant ricinuleids, with 11 species described from tropical West Africa, is the most neglected of the three genera currently recognized. A lack of attention to the systematics of Ricinoides has created a disparity between its taxonomic diversity and that of the New World genera, CryptocellusWestwood, 1874, and PseudocellusPlatnick, 1980, in which many new species have been described in recent decades. The present contribution provides a revised diagnosis of Ricinoides, which includes two new, putative synapomorphies for the genus and addresses the systematics and morphology of a group of West African species, which includes the world's largest ricinuleids and the type species of the genus. This group of nine species, referred to as the “giant” Ricinulei, shares a unique combination of characters, many of which appear to be unique to the group, and appears to be monophyletic. Four species of this group are redescribed, with revised diagnoses, based on reexamination of the type material: Ricinoides afzelii (Thorell, 1892), from Sierra Leone; Ricinoides atewaNaskrecki, 2008, from Ghana; Ricinoides feae (Hansen, 1921), from Guinea-Bissau; and Ricinoides westermannii (Guérin-Méneville, 1838), from Togo. Five new species are described, raising the number of species in the genus to 16: Ricinoides eburneus, sp. nov., and Ricinoides taii, sp. nov., from Côte d'Ivoire; Ricinoides iita, sp. nov., from Nigeria; Ricinoides kakum, sp. nov., from Ghana; and Ricinoides nzerekorensis, sp. nov., from Guinea. Comparative illustrations of the adult morphology are presented for all nine species. The male copulatory apparatus is described and illustrated in detail, and new terminology and characters presented. The female spermathecae are described and illustrated for six species in which the females are known, representing the first illustrated comparison of these structures in African ricinuleids. Geographical distribution records are revised and updated for the different species, and their distributions mapped.