Two New Cave-Dwelling Species of the Short-Tailed Whipscorpion Genus Rowlandius (Arachnida: Schizomida: Hubbardiidae) from Northeastern Brazil, with Comments on Male Dimorphism

Adalberto J Santos,Bruno A Buzatto,Rodrigo Lopes Ferreira,Donald James Colgan

doi:10.1371/journal.pone.0063616

Adalberto J Santos, Bruno A Buzatto + Show 2 more

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https://doi.org/10.1371/journal.pone.0063616

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Abstract

Two new species of the arachnid order Schizomida, Rowlandius ubajara sp.nov. and Rowlandius potiguar sp.nov., are described based on both male and female specimens collected in caves from northeastern Brazil. Rowlandius ubajara is known only from the Ubajara Cave, in the state of Ceará; R. potiguar is recorded from 20 caves of the Apodi Limestone Group, in the state of Rio Grande do Norte. A remarkable dimorphism in male pedipalp length is described and analyzed in R. potiguar. The distribution of male pedipalp length is clearly bimodal in the species, but the two male morphs (homeomorphic and heteromorphic) present some overlap in the sizes of this structure. Moreover, males show a steeper allometry in pedipalp length than females, indicating that this trait is under a different selective regime in males and in females.

Highlights

The arachnid order Schizomida, the short-tailed whipscorpions, is represented in South America mainly in northern forested areas
The only species known from southern parts of the subcontinent was Stenochrus portoricensis Chamberlin, 1922 [1,2], a widespread and synanthropic species
Males with less than 95% chances of belonging to either male morph were left out when adjusting the allometric relationships between pedipalp length and prosoma length for homeomorphic and heteromorphic males

Summary

Introduction

The arachnid order Schizomida, the short-tailed whipscorpions, is represented in South America mainly in northern forested areas. Two new species are described based on specimens collected in cave habitats in northeastern Brazil. Several species of Rowlandius and other genera of schizomids are known by the remarkable variation in the length of male pedipalp. The length of the male pedipalp can vary from approximately the same size as those of the female to up to three times as long

Results

Conclusion