A new nurse frog of the Allobates tapajos species complex (Anura: Aromobatidae) from the upper Madeira River, Brazilian Amazonia

Abstract

Cryptic diversity is extremely common in widespread Amazonian anurans, but especially in nurse frogs of the genus Allobates. There is an urgent need to formally describe the many distinct but unnamed species, both to enable studies of their basic biology but especially to facilitate conservation of threatened environments in which many are found. Here, we describe through integrative taxonomy a new species of the Allobates tapajos species complex from the upper Madeira River, southwestern Amazonia. Species delimitation analyses based on molecular data are congruent and delimit five candidate species in addition to A. tapajos sensu stricto. The new species is recovered as sister to A. tapajos clade F, a candidate species from Teles-Pires River, southeastern Amazonia. The new species differs from nominal congeners in adult and larval morphology and in male advertisement call. Egg deposition sites differ between east and west banks of the upper Madeira River, but there is no evidence of corresponding morphologic or bioacoustic differentiation. The new species appears to be restricted to riparian forests; its known geographic range falls entirely within the influence zone of reservoirs of two large dams, which underscores the urgent need of a conservation assessment through long-term monitoring. This region harbors the richest assemblage of Allobates reported for Brazilian Amazonia, with six nominal species and four additional candidate species awaiting formal description.

Two new species of Allobates of the trilineatus clade (Anura: Aromobatidae) from the Eastern Guiana Shield

“…We gathered all the 16S sequences available in GenBank forming the A. granti and the A. tapajos complexes according to Vacher et al (2020) and Ferrão et al (2022) (Appendix 1). We employed BLASTN to verify that no other 16S sequence deposited on GenBank after these works clustered with the species used in this study.…”

“…nov.) we measured 20 adult specimens (14 males and six females), seven of which were genotyped in previous papers and five were recorded (Appendix 2). The measurements of the latter specimens were compared to the related A. tapajos sensu stricto and A. kamilae using the data of Ferrão et al (2022).…”

“…With 20 (35%) of the nominal species having been described since 2010 (e.g. Lima et al 2020;Melo-Sampaio et al, 2020;Souza et al 2020;Gagliardi-Urrutia et al 2021;Moraes & Lima 2021;Ferrão et al 2022;Silva et al 2022) and with the existence of many additional putatively unnamed species (Réjaud et al 2020;Vacher et al 2020;Ferrão et al 2022), this genus also exemplifies the large proportion of yet undocumented diversity of frogs inhabiting Amazonia. This pattern has been highlighted many times already, notably in the Guiana Shield by DNA-based estimations (e.g.…”

“…Additionally, another lineage related to Allobates tapajos Lima, Simões, and Kaefer, 2015 was documented from French Guiana (Vences et al 2003;Fouquet et al 2007;2012) and more populations were later found in Suriname (Fouquet et al 2015a) and northern Pará (identified as A. spumaponens Ernst, 2007 by Avila-Pires et al 2010). This lineage is nested within a clade formed by populations from the southern margin of the Amazon River (Réjaud et al 2020;Ferrão et al 2022; Fig. 1), which altogether form six major lineages: two are found in the Tapajós-Xingu interfluve including A. tapajos (Lima et al 2015), three in the Madeira-Tapajós interfluve including A. kamilae Ferrão, Hanken, and Lima, 2022, leaving possibly four candidate species remaining unnamed within the complex.…”

“…This lineage is nested within a clade formed by populations from the southern margin of the Amazon River (Réjaud et al 2020;Ferrão et al 2022; Fig. 1), which altogether form six major lineages: two are found in the Tapajós-Xingu interfluve including A. tapajos (Lima et al 2015), three in the Madeira-Tapajós interfluve including A. kamilae Ferrão, Hanken, and Lima, 2022, leaving possibly four candidate species remaining unnamed within the complex. The divergence between the Guiana Shield populations and their closest southern relatives is estimated to date back some 5 Ma, thus suggesting that they might correspond to distinct species (Réjaud et al 2020).…”