Nelson Ferretti, Matías Beratz

Descriptions of undescribed sexes of Theraphosidae spiders (Mygalomorphae: Plseiopelma, Tmesiphantes) from northern Argentina

Introduction

Descriptions of undescribed sexes of theraphosidae spiders (mygalomorphae: plseiopelma, tmesiphantes) from northern argentina. First descriptions of previously unknown female Theraphosidae spiders (Plesiopelma paganoi & Tmesiphantes crassifemur) from northern Argentina, with new diagnoses & distribution.

Abstract

Females previously unknown from two Argentinean tarantula (Theraphosidae), Plesiopelma paganoi Ferretti & Barneche, 2014 and Tmesiphantes crassifemur (Gerschman & Schiapelli, 1960) are described for the first time. Both specimens were collected at the type locality or very close to it to assure to be conspecific. The female of P. paganoi can be distinguished from congeners by the high number of labial and maxillary cuspules and the shape of the spermathecae with very short and non-spiraled ducts. The female of T. crassifemur is characterized by the shape of the spermathecae and the absence of spiniform setae on coxa III and IV. New diagnosis are presented and a distribution map of both species.

Review

This manuscript presents a valuable and well-executed contribution to tarantula taxonomy, specifically addressing the descriptions of previously undescribed sexes within the Theraphosidae family from northern Argentina. The authors focus on the females of *Plesiopelma paganoi* and *Tmesiphantes crassifemur*, species where only the male sex was previously known. This work is significant as the description of both sexes is fundamental for robust species delimitation, accurate identification, and a comprehensive understanding of biodiversity within these poorly known Neotropical genera. A major strength of this study lies in the careful collection methodology, ensuring conspecificity by collecting specimens at or very close to the type localities. The abstract clearly indicates that the descriptions are thorough, utilizing key diagnostic characters such as the number of labial and maxillary cuspules, the distinctive shape and structure of the spermathecae (e.g., very short and non-spiraled ducts in *P. paganoi*), and the presence or absence of spiniform setae on specific coxae (*T. crassifemur*). The inclusion of new diagnoses for both species, incorporating these newly described female characters, and a distribution map further enhances the utility and scientific rigor of the work. Overall, this paper provides essential taxonomic information that significantly advances our knowledge of these Argentinean tarantula species. The detailed morphological descriptions of the female specimens, coupled with the robust approach to specimen identification, contribute substantially to the systematic understanding of *Plesiopelma* and *Tmesiphantes*. Such foundational taxonomic work is critical for subsequent ecological, phylogenetic, and conservation studies. This manuscript is a solid, direct contribution to arachnological systematics and is strongly recommended for publication.

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