Species diversity and systematics of the Leptodactylus melanonotus group (Anura, Leptodactylidae): review of diagnostic traits and a new species from the Eastern Guiana Shield

Abstract

The Leptodactylus melanonotus species group is an anuran clade widely distributed in the Neotropics. This clade harbours many species that are difficult to identify because of incomplete taxonomic knowledge, ambiguous species boundaries and distribution. Here we expand the understanding of species diversity of this Leptodactylus clade by analysing mtDNA sequences for over 600 individuals, delimiting Operational Taxonomic Units (OTUs), and updating species identifications and distributions by linking sequences to morphotypes and calls. Also, we review the morphological and acoustic traits traditionally used as diagnostic characters of species within this group. The DNA-based species delimitation analyses yielded 57 OTUs. Given that only 19 taxa are currently recognized as valid species, our results suggest the existence of many unnamed species within the L. melanonotus group. After reassessing morphological traits in the group, we concluded that the combined use of dorsolateral fold, upper lip stripe, and belly colouration is sufficiently informative for species identification in most cases, especially when associated with data on geographic distribution and habitat use. Regarding advertisement calls, the patterns of amplitude and frequency modulation, calling rate, and dominant frequency were also informative for species discrimination. Furthermore, we designate a neotype for L. wagneri, for which we also describe the advertisement call, and make comparisons with congeners of the L. melanonotus group, especially with the partially sympatric L. leptodactyloides. Lastly, we name and describe a new species endemic to the Eastern Guiana Shield. Patterns of distribution and habitat use in the L. melanonotus group revealed that sympatric occurrences are more commonly found among distantly related species, whereas allopatric occurrences correspond to closely related ones. Speciation between closely related species of the group seems to be related to ecological divergence (open vs. forest habitats) in parallel with clear morphological and acoustic differentiation.

http://www.zoobank.org/urn:lsid:zoobank.org:pub:867A8EA9-A8F2-4FA4-8746-A0D9BB2E4286

Key words:

• advertisement calls
• Amazonia
• biodiversity
• calling habitat
• integrative taxonomy
• Leptodactylinae
• Neotropics
• phylogeny

Acknowledgements

We are grateful to W. Ronald Heyer, A. Wynn, and James Pointdexter (USNM), L. Felipe Toledo and Simone Dena (FNJV), R. Márquez (Fonoteca Zoológica de Madrid), The Macaulay Library at the Cornell Lab of Ornithology, and J. Roger Downie for enabling access to sound recordings of leptodactylid frogs. We thank F. Pedroso, J.C. de Sousa, M. Dias, P.S. Souza, and R. Tavares for their helpful assistance during the fieldwork; A. Réjaud, E. Gibson, and R. Fernandez helped with the data gathering and analyses; A. Camacho, A. Réjaud, B.P. Noonan, D. Baudain, D. Dittmann, de A. Percequillo, E. Courtois, F. Arias, F. Dal Vechio, I. Prates, J. Allen, J. Chretien, J. Dias Lima, J.M.B. Ghellere (and students of his lab), K. Pineau, L. Barthe, M. Berroneau, M. Blanc, M. Chouteau, M. Dewynter, M. Sena, M. Teixeira Jr., O. Chaline, P. Dias, P. Kok, P.O. Cochard, R. Jairam, R. Recoder, S. Neilsen, S.M. Souza, and V. Premel contributed with field sampling and/or tissue loan. We thank L.J.C.L. Moraes for critically reading an earlier version of the manuscript and providing valuable suggestions. We are grateful to an anonymous reviewer and the Associate Editor David Gower for their comments and suggestions that improved the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplemental material

Supplemental material for this article can be accessed here: http://dx.doi.org/10.1080/14772000.2022.2089269.

Associate Editor: Dr David Gower

Additional information

Funding

This work was supported by the São Paulo Research Foundation in Brazil (Fundação de Amparo à Pesquisa do Estado de São Paulo [FAPESP] processes #2003/10335-8, #2011/50146-6, #2012/15763-7, #2013/50741-7, #2017/08489-0, # 2018/03428-5, and #2018/17118-8) and the National Council for Scientific and Technological Development (Fundação de Amparo à Pesquisa do Estado de São Paulo [CNPq] grant #446935/2014-0 to AAG; #301778/2015-9 to MTR; and #306623/2018-8 to CFBH; postdoctoral fellowship #163918/2020-1 to TRC). This work also benefited from an ‘Investissement d’Avenir’ grant managed by the Agence Nationale de la Recherche (CEBA, ref. ANR-10-LABX-25-01, TULIP, ref. ANR-10-LABX-41; ANR-11-IDEX-0002-02). Field and laboratory work in Ecuador were funded by Secretaría Nacional de Educación Superior, Ciencia, Tecnología e Innovación del Ecuador SENESCYT (Arca de Noé initiative; SRR and Omar Torres principal investigators) and grants from Pontificia Universidad Católica del Ecuador, Dirección General Académica. A collecting permit was issued by the Brazilian government (ICMBio/SISBIO #30059).