Cladistic analysis of the Brazilian troglobitic harvestmengenusIandumoemaPinto-da-Rocha (Opiliones:Gonyleptidae) with the description of three new species:a brief exercise over the use of troglomorphisms in cladisticanalysis

Abstract

From an ecological and evolutionary standpoint, troglobitic organisms are of special interest because theyhave evolved in, and are restricted to, the subterranean environment.IandumoemaPinto-da-Rocha, 1997 stands out forbeing the only Brazilian harvestmen genus with more than one troglobitic species, with three species described fromcaves in Minas Gerais state. Traditionally, testing the monophyly of troglobitic groups is more challenging than testinggroups that do not include troglobites. Many of their shared features might be the result of convergence or parallelismimposed by the cave environment, such as the absence of light, limited and infrequent availability of food resources andlow population density, among others. In the case ofIandumoema, this becomes even more difficult because the genus iscurrently included in the species-rich and polyphyletic subfamily Pachylinae. This study tested the monophyly of thistroglobitic genus and proposed thefirst phylogenetic hypothesis forIandumoemabased on cladistic analysis usingmorphological data. The analysis included all described species ofIandumoemaand three new troglobitic species:I. cuca, sp. nov. (type locality: Itacarambi, Gruta da Água do João Ferreira);I. gollum, sp. nov. (type locality: PresidenteJuscelino, Lapa D’Água); andI. stygia, sp. nov. (type locality: Montes Claros, Gruta do Cedro). The matrix comprises79 characters and 28 terminal taxa: six species ofIandumoema; 14 of Pachylinae; six from other Gonyleptidaesubfamilies; one species of Cosmetidae; and one of Metasarcidae. The cladistic analysis resulted in one parsimonioustree (339 steps, consistency index = 0.35, retention index = 0.56).Iandumoemais a monophyletic and well supportedgenus, nestled among Brazilian‘Pachylinae’. Three new species are described and an identification key and ecologicalremarks for all six species of the genusIandumoemais provided.