A closer look at Batillipes dicrocercus and new records of Batillipes potiguarensis (Tardigrada: Arthrotardigrada) from the Brazilian coast with comments on intra- and interspecific variability

Érika Santos,Paulo Fontoura,Clélia M C Da Rocha,Edivaldo Gomes Jr,Paul J Bartels

doi:10.1590/1678-4766e2018041

Abstract

ABSTRACT Batillipes specimens collected in the Southwestern Atlantic Ocean, on the Brazilian Coast (Campos Basin and Potiguar Basin) with a bifurcated caudal appendage similar to B. dicrocercus Pollock, 1970 were assigned to B. potiguarensis Santos, da Rocha, Gomes Jr & Fontoura, 2017. This species was described as having a roundish caudal protrusion but, as shown in this study, it exhibits intraspecific variability of the morphology of the caudal apparatus. The examination of specimens of B. dicrocercus from the type locality (Massachussetts, U.S.A.) and the analysis of the original description and two subsequent emended descriptions, one from the Gulf of Mexico (U.S.A.) and another from the Mediterranean Sea, used for comparison, revealed important differences among them concerning important taxonomic characters, suggesting that what was considered a single species should now be split into three different species. Therefore, an emended diagnosis of B. potiguarensis and comments on the geographic distribution of B. dicrocercus are provided, clarifying the taxonomic status of the two species.

Highlights

This fact demanded a deeper morphological study of B. potiguarensis, a species recently described from Brazil (Santos et al, 2017), in order to know if in this species the caudal apparatus displays intraspecific variability or if the Batillipes from this collection belong to two distinct species
Measurements, given in micrometers, and photomicrographs were made under 100x oil immersion, using a Phase Contrast Microscope (PHC) and a Differential Interference Contrast Microscope (DIC), both equipped with digital cameras and using Zen Imaging Software
Based on the bifurcated aspect of caudal apparatuses, the examined specimens from Brazil could be confused with B. dicrocercus

Summary

Introduction

During a recent survey of marine tardigrades in the Brazilian states of Rio de Janeiro and Rio Grande do Norte mixed populations of Batillipes specimens exhibiting both a bifurcate caudal appendage or a roundish caudal protrusion as observed in B. potiguarensis Santos, da Rocha, Gomes Jr & Fontoura 2017, were collected. This fact demanded a deeper morphological study of B. potiguarensis, a species recently described from Brazil (Santos et al, 2017), in order to know if in this species the caudal apparatus displays intraspecific variability or if the Batillipes from this collection belong to two distinct species. An emended diagnosis of B. potiguarensis and comments on the geographic distribution of B. dicrocercus are provided, clarifying the taxonomic status of the two species

Methods

Results

Conclusion