Rebuilding the Cytogenetics of Atelognathus (Anura: Batrachylidae): Half a Century of Confusion

Abstract

The genus Atelognathus is currently composed of five species that occur in thesouthernmost region of Argentina and Chile. It belongs to the Batrachylidae along with Batrachyla, Chaltenobatrachus, and Hylorina, one of the few endemic anuran families from Patagonia. The first literature to mention the cytogenetics of Atelognathus was about 50 years ago, where it was stated that A. reverberii had a diploid chromosomal complement of 2N = 26, a feature later reported for other congenerics. Over the past two decades, we compiled cytogenetic information of all known species of Atelognathus: A. nitoi, A. patagonicus, A. praebasalticus, A. reverberii, and A. solitarius. Unexpectedly, our analyses showed that all of them have a diploid chromosomal complement 2N = 24, whichcontrasts with those observed by other authors. In this study, we describe thecytogenetics of all recognized Atelognathus species and two additional undetermined populations. We conclude that a karyotype of 2N = 24 is shared in Atelognathus, as a derived condition within Batrachylidae. Additionally, we describe and discuss other cytogenetics characters (i.e., NORs location and C-banding patterns) of Atelognathus and related genera of Batrachylidae in an evolutionary framework.