Under threat: Two new troglobitic species of Girardia (Platyhelminthes: Tricladida) from sandstone and limestone caves in Brazil

Abstract

The diversity of freshwater triclads of the suborder Continenticola in the Neotropical region is poorly known, with few studies in South America. In this work, we describe two new cave-dwelling species of Girardia: G. corumbataiensis sp. nov. is described from a single sandstone cave located in an area covered by semi-deciduous vegetation, southeastern Brazil; G. nobresis sp. nov. is described from a single flooded limestone cave located in an area of Cerrado vegetation, central-western Brazil. Specimens of G. corumbataiensis sp. nov. have a slight pigmented dorsal surface with highly triangular head and two eyes, whereas specimens of G. nobresis sp. nov. lack body pigmentation and eyes and have pointed auricles. Girardia corumbataiensis sp. nov. shows a pear-shaped bulbar cavity with forked portions turned dorsally and a slightly bent bursal canal. Girardia nobresis sp. nov. has an ample bulbar cavity with numerous folds and an angled bursal canal. The two new species are categorized as troglobites and easily recognized by a unique combination of characters of their external morphology and copulatory apparatus. G. corumbataiensis sp. nov. occurs in a cave inserted in a protected area, but no effective action for preservation has been provided. This species is abundant in a single stream crossing the cave, which is subject to intensive visitation and control of bat populations, besides Eucalyptus plantations nearby. The type-locality of G. nobresis sp. nov., a single flooded cave near a municipal road, has no legal protection. There are impacts, such as intensive visitation for fishing and deforestation in its surroundings.