Taxonomic revision and cladistic analysis of Pachylospeleinae Silhavý and Metagyndes Sorensen and their respective genera putatively close phylogenetically (Arachnida: Opiliones: Gonyleptidae): tackling the Pachylinae poliphyly in two fronts

Abstract

The systematics of neotropical harvestmen has advanced in the last three decades thanks to the inclusion of new data sources. The family Gonyleptidae stands out as the main component of the Brazilian harvestmen fauna, being the best studied, with 16 subfamilies. Among the unrevised subfamilies, Pachylinae is one of the greatest challenges because of its polyphyly and being the richest in species number. Phylogenetic studies using molecular data detected seven main clades in Pachylinae, among which Pachylinae sensu stricto stands out, being composed mainly of Chilean genera. This clade is composed of Pachylus paessleri Roewer, 1913, Acanthopachylus aculeatus (Kirby, 1818), Metgyndes martensii (Sorensen, 1902), and Acanthoprocta pustulata Loman, 1899, and it is of special interest because includes the type genus of the subfamily. Therefore, it will be probably recognized as the true Pachylinae in near future. Testing the monophyly of the genera phylogenetically close to Pachylus is the next important taxonomical step to propose a congruent classification following the modern standards. In this clade, Metagyndes stands out as one of the oldest and richest unrevised genus, being composed of eight species and sister group of Pachylus + Acanthopachylus. Revision and cladistic analysis of Metagyndes will allow for testing its monophyly as well as the putative synapomorphy of Pachylinae sensu stricto. Calcarogyndes Mello-Leitão, 1932, Pseudogyndes Mello-Leitão, 1932 and Gyndulus roeweri (Soares & Soares, 1954) will also be included in the revision due to their resemblance with Metagyndes. Another Pachylinae main clade that stands out is the one that includes a clade composed by the group Pachylospeleus strinatii Silhavý, 1974, Hypophyllonomus longipes Giltay, 1928 and Pseudogyndesoides latus B. Soares, 1944b, and the group Ogloblinia loretoensis Canals, 1933 and Triglochinura curvispina Mello-Leitão, 1924. These two groups share a relatively homogeneous morphology and based on it, they also should include Gyndesoides Mello-Leitão, 1933, Passosa Roewer, 1927, Singram Mello-Leitão, 1937 and Uropachylus Mello-Leitão, 1922. This Pachylinae clade altogether includes ca. 30 species in nine unrevised genera. Therefore, identifying a species of such clade is complex and uncertain task. This context hampers the detection of new species as well as ecological studies, such as diversity evaluation and landscape fragmentation effects, especially in the southeastern Brazilian Atlantic Rain Forest, where they occur. Many harvestmen based endemism and biogeographical studies also use species that occur in that vegetation physiognomy. Therefore, the proposed revision under a cladistic perspective will contribute to improve the understanding of the Atlantic Rain Forest harvestmen biogeography. This project is a step forward to solve the Pachylinae polyphyly, proposing monophyletic groups using morphological characters, according to the current study trend of the group. (AU)