A new species of Engystomops (Anura: Leiuperidae) from southwestern Ecuador

Abstract

We describe Engystomops puyango sp. nov. from the lowlands of southwestern Ecuador. The new species is closely related to E. pustulatus from which it differs in skin texture, advertisement call, and karyotype features. The new species also differs from E. pustulatus at genes 12S and 16S of mitochondrial DNA (6.5%–6.8% of sequence divergence). A phylogeny based on mtDNA shows that E. sp. nov. is part of a clade of Engystomops distributed below 1300 m in western Ecuador and northwestern Peru. The new species occurs in Evergreen Lower Montane Forest and Foothill Semideciduous Costa Forest. The karyotype of the new species has 2n = 20 chromosomes which represents the first known reduction in chromosome number in Leiuperidae (2n = 22). Its advertisement calls as well as those of E. pustulatus have a facultative component that resembles the chuck in calls of E. pustulosus but that are less discrete and have lower acoustic complexity.

Karyotypic differentiation via 2n reduction and a finding of a case of triploidy in anurans of the genus Engystomops (Anura, Leiuperidae)

“…The diploid number of the five Engystomops species studied here was 2n = 20, the same 2n reported previously for E. pustulatus and E. puyango (Ron et al 2010 Silva et al 1999Silva et al , 2000Amaral et al 2000;Quinderé et al 2009;Tomatis et al 2009;Milani et al 2010;Nascimento et al 2010), which is considered to be the sister-group of Engystomops (Ron et al 2006;Nascimento et al 2005). Therefore, we conclude that the 2n reduction from 2n = 22 to 2n = 20 is a synapomorphy of Duovox clade of Engystomops.…”

“…The 2n = 20 karyotypes found in the six species of the Duovox clade (described herein and in Ron et al 2010) are very similar to each other, both in the morphology of each chromosome pair and in the NOR location in chromosome 9. Some differences in the arm ratio value/centromeric index could be observed when presumed homeologous chromosomes of the karyotypes presented here were compared with those of E. puyango and E. pustulatus described by Ron et al (2010).…”

“…We also provide a detailed characterization of E. pustulatus karyotype, expanding the cytogenetic data previously reported by Ron et al (2010) for this species. A triploid specimen was found among the specimens of E. coloradorum and its karyotype is also described.…”

“…The phylogeny of the Engystomops species proposed by Ron et al (2006) allocated the species from Western Ecuador and Northwestern Peru in a clade called Duovox, which is composed of the species Engystomops coloradorum (Cannatella and Duellman 1984), Engystomops guayaco (Ron et al 2005), Engystomops montubio, Engystomops randi (Ron et al 2004), Engystomops pustulatus (Shreve 1941), and Engystomops puyango (Ron et al 2010). The sister group of this clade was named Edentulus and comprised Engystomops pustulosus and the Amazonian species Engystomops freibergi and Engystomops petersi (Ron et al 2006).…”

“…On the other hand, E. puyango and E. pustulatus showed a karyotype composed of 2n = 20 (Ron et al 2010), raising a question about when the 2n reduction has occurred.…”