Elachistocleis Parker, 1927

Class: Amphibia > Order: Anura > Family: Microhylidae > Subfamily: Gastrophryninae > Genus: Elachistocleis
18 species

Microps Wagler, 1828, Isis von Oken, 21: 744. Type species: Microps unicolor (= Elachistocleis ovalis), by monotypy. Preoccupied by Microps Megerle, 1823. Synonymy with Engystoma by Duméril and Bibron, 1841, Erp. Gen., 6: 738; Boulenger, 1882, Cat. Batr. Sal. Coll. Brit. Mus., Ed. 2: 160. Regarded as a synonym of Gastrophryne by Fouquette and Dubois, 2014, Checklist N.A. Amph. Rept.: 379, for undisclosed reasons. Junior homonym of Microps Dahl, 1823 (Insecta), according to Dubois, Ohler, and Pyron, 2021, Megataxa, 5: 513. 

Stenocephalus Tschudi, 1838, Classif. Batr.: 86. Type species: Stenocephalus microps Tschudi, 1838, by monotypy. Preoccupied by Stenocephalus Latreille, 1825. Synonymy with Engystoma by Duméril and Bibron, 1841, Erp. Gen., 6: 738; Boulenger, 1882, Cat. Batr. Sal. Coll. Brit. Mus., Ed. 2: 160. Regarded as a synonym of Gastrophryne by Fouquette and Dubois, 2014, Checklist N.A. Amph. Rept.: 379, for undisclosed reasons.

Elachistocleis Parker, 1927, Occas. Pap. Mus. Zool. Univ. Michigan, 187: 4. Type species: Rana ovalis Schneider, 1799, by original designation. See comment.

Relictivomer Carvalho, 1954, Occas. Pap. Mus. Zool. Univ. Michigan, 555: 13. Type species: Hypopachus pearsei Ruthven, 1914, by original designation. Synonymy by de Sá, Streicher, Sekonyela, Forlani, Loader, Greenbaum, Richards, and Haddad, 2012, BMC Evol. Biol., 12(241): 1–21.

English Names

Oval Frogs (Frank and Ramus, 1995, Compl. Guide Scient. Common Names Amph. Rept. World: 89; Hedges, Powell, Henderson, Hanson, and Murphy, 2019, Caribb. Herpetol., 67: 14). 

Plump Frogs (Relictivomer [no longer recognized]: Frank and Ramus, 1995, Compl. Guide Scient. Common Names Amph. Rept. World: 92).

Distribution

Panama and Colombia southward, east of the Andes, to southern Paraguay, southeastern Bolivia, central Argentina, central and southeastern Brazil and Uruguay; Trinidad; west of the Andes in Azuay Province, Ecuador. 

Comment

Probably derived from Relictivomer and possibly ancestral to Synapturanus and Myersiella according to Carvalho, 1954, Occas. Pap. Mus. Zool. Univ. Michigan, 555: 15, although this view has not survived subsequent phylogenetic work (see subfamily and family accounts). Pyron and Wiens, 2011, Mol. Phylogenet. Evol., 61: 543–583, suggested Elachistocleis to be the sister taxon of Hypopachus + Gastrophryne. See Dubois, 1987, Alytes, 6: 75–84, on proposed conservation of the generic name and discussion of senior synonyms and type species. See Cei, 1987, Monit. Zool. Ital., N.S., Suppl., 21: 215, for discussion of confusion surrounding taxonomy of the genus. Lavilla, Vaira, and Ferrari, 2003, Amphibia-Reptilia, 24: 269–284, provided a tentative identification framework of the species, and expanded on the problems of Elachistocleis taxonomy—required reading for anyone attempting identifications within this genus. Nunes, Canedo, and Carvalho, 2010, S. Am. J. Herpetol., 5: 30–34, discussed the distribution of the commissural gland within this taxon. Caramaschi, 2010, Bol. Mus. Nac., Rio de Janeiro, N.S., Zool., 527: 1–30, discussed the difficult nomenclatural and taxonomic history of this taxon and considered the type species, Rana ovalis Schneider, to be a nomen dubium. This has the effect of leaving populations from Panama, Colombia, Venezuela, Peru, Ecuador, Trinidad and Tobago, Guyana, French Guiana, and Surinam without a name. Jansen, Bloch, Schulze, and Pfenninger, 2011, Zool. Scripta, 40: 567–583, reported on two unnamed species in Amazonian Bolivia, based on genetic data. Laufer, Pereyra, Akmentins, and Borteiro, 2013, Zootaxa, 3710: 498–500, discussed larval morphology. Weiler, Núñez, Airaldi, Lavilla, Peris, and Baldo, 2013, Anf. Paraguay: 116, provided a brief account, image, and dot map for Paraguay. Schulze, Jansen, and Köhler, 2015, Zootaxa, 4016: 85–87, described, diagnosed, and pictured the larva of Elachistocleis sp. from Amazonian Bolivia. Ferraro, Blotto, Baldo, Barrasso, Barrionuevo, Basso, Cardozo, Cotichelli, Faivovich, Pereyra, and Lavilla, 2018, in Vaira, Akmentins, and Lavilla (eds.), Cuad. Herpetol., 32 (Supl. 1): 17–19, noted that various populations in Argentina require taxonomic elucidation. Vaz-Silva, Maciel, Nomura, Morais, Guerra Batista, Santos, Andrade, Oliveira, Brandão, and Bastos, 2020, Guia Ident. Anf. Goiás e Dist. Fed. Brasil Central: 156–157, noted two species that are apparently unnamed in Goiás, Brazil. Jowers, Othman, Borzée, Rivas-Fuenmayor, Sánchez-Ramírez, Auguste, Downie, Read, and Murphy, 2021, Organisms Divers. Evol., 21: 189–206, made an heroic effort to unravel this complex of species, including discussion of molecular relationships, calls, and comparative morphology, as well as preliminary range maps. Novaes-e-Fagundes, Lyra, Loredam, Carvalho, Haddad, Rodrigues, Baldo, Barrasso, Loebmann, Ávila, Brusquetti, Prudente, Wheeler, Orrico, and Peloso, 2023, Zool. J. Linn. Soc., 197: 545–568, revised the genus and provided a molecular tree of the species, which suggested that Elachistocleis is paraphyletic with respect to Gastophryne + Hypopachus, although they did not offer any taxonomic remedy. 

Contained taxa (18 sp.):

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