Review of Trichodamon Mello-Leitao 1935 and phylogenetic placement of the genus in Phrynichidae (Arachnida, Amblypygi)

Amblypygi Thorell, 1883 has five families, of which Phrynichidae is one of the most diverse and with a wide geographic distribution. The genera of this family inhabit mostly Africa, India and Southeast Asia, with one genus known from the Neotropics, Trichodamon Mello-Leitao, 1935. Trichodamon has two valid species, T. princeps Mello-Leitao, 1935 and T. froesi Mello-Leitao, 1940 which are found in Brazil, in the states of Bahia, Goias, Minas Gerais and Rio Grande do Norte. The boundaries of the species are not well established and the characters classically used in the group are poorly defined. The relationship of Trichodamon to the other genera in the family is also subject to debate. Some phylogenetic hypotheses propose Trichodamon as sister to Eurphynichus Weygoldt, 1995 and Phrynichus Karsch, 1879, in the subfamily Phrynichinae. Others suggest Trichodamon in Damoninae, sister to Damon and Phrynichodamon Weygoldt, 1996. The present work has the aim to characterize Trichodamon species, update the species distribution and ascertain the phylogenetic position of the genus in Phrynichidae using morphological characters. Our results show that the diagnostic characters of Trichodamon species, i.e. number of spines on the pedipalp, shape of the frontal process, number of teeth on the chelicerae, male and female shape of gonopods, are highly variable. A gradual colour variation from the northern to the southern areas of the distribution is also present. In face of the high variability, the synonymy of Trichodamon froesi (syn. jun.) with T. princeps is suggested. The cladistic analysis recovered Trichodamon as sister to Phrynichus + Euphrynichus in the subfamily Phrynichinae supported by eight characters, one exclusive to the group (dorsal spines on pedipalp patella positioned on the apex of the article forming the phrynich hand). In Damoninae, Phrynichodamon Weygoldt, 1996 was found as sister to Damon, forming the tribe Damonini, a group supported by the number of ventral spines on pedipalp femur; Musicodamon was recovered as sister to Damonini, forming the subfamily Damoninae, and the Glade can be recognized by the presence of sclerotization on the apex of the claw-like projection of the female gonopod. The unranked taxon Euphrynichida Weygoldt, 2000 (Phrynichinae + Damoninae) was recovered with good support and is identified by the rectangular shape of the female gonopod and by the presence of one spine on the proximal series on pedipalp femur. (C) 2018 Elsevier GmbH. All rights reserved.