Elachistocleis cesarii (MirandaRibeiro, 1920)

Novaes-E-Fagundes, Gabriel, Lyra, Mariana L., Loredam, Vinicius S. A., Carvalho, Thiago R., Haddad, Célio F. B., Rodrigues, Miguel T., Baldo, Diego, Barrasso, Diego A., Loebmann, Daniel, Ávila, Robson W., Brusquetti, Francisco, Prudente, Ana L. C., Wheeler, Ward C., Orrico, Victor Goyannes Dill & Peloso, Pedro, 2023, A tale of two bellies: systematics of the oval frogs (Anura: Microhylidae: Elachistocleis), Zoological Journal of the Linnean Society 197, pp. 545-568 : 560-561

The status of Elachistocleis cesarii ,

E. piauiensis and E. magna

Miranda-Ribeiro (1920) described two subspecies of Engystoma ovale based on maculate-bellied specimens from the state of São Paulo, Brazil, which were later synonymized by Parker (1934) with Elachistocleis ovalis . Toledo et al. (2010) recently resurrected and redescribed them under the new combination Elachistocleis cesarii . Herein we recognize E. cesarii as a species distributed in south-eastern and central-western Brazil ( Fig. 3 ) and closely related to E. piauiensis and E. magna ( Fig. 1 ).

Elachistocleis piauiensis was described and named by Caramaschi & Jim (1983) from Picos, Piauí. We found four lineages distributed in north-eastern Brazil, but we could not confidently assign any to E. piauiensis , because we did not have access to data from the type locality. Specimens assigned to each of these four lineages are morphologically similar to each other and to the original species description of E. piauiensis . The ventral colour pattern varies widely and similarly along the clade composed of E. cesarii , E. magna and the four candidate species E. cf. piauiensis 1–4, with no clear difference between them. The presence/absence of the mid-dorsal line also varies, except for E. cf. piauiensis 3, in which all examined vouchers lack the line. The holotype of E. piauiensis also lacks the line, and this could be evidence to assign the name to this specific clade. However, we cannot rule out that the consistent absence in E. cf. piauiensis 3 is not an effect of our sampling, given the high variability of this character state in several of our delimited species ( Fig. 1 ).

Elachistocleis cesarii was distinguished from E. piauiensis by differences in the advertisement call, size of the post-commissural gland and details of the inguinal region colouration ( Toledo et al., 2010) – phenotypic traits that we have not explored for the present contribution. On the other hand, E. magna was distinguished from E. cesarii and E. piauiensis solely by its size (male SVL above 31 mm in E. magna , against SVL below 29 mm in E. cesarii and E. piauiensis ; Toledo, 2010). Among examined specimens, we observed a consistent difference in size between E. magna and E. cf. piauiensis 1–4, but not between E. magna and E. cesarii . Males of E. cesarii can have SVL up to 31 mm, whereas some males of E. magna have SVL below 29 mm. Therefore, a thorough evaluation of phenotypic data allied with a denser molecular sampling is needed to verify if the differential diagnoses among E. cesarii , E. piauiensis and E. magna will hold true with additional data.

Figures

Figure 1. Species delimitation in Elachistocleis. The tree shown is from the maximum likelihood (ML) analysis with only 16S + COI from only Elachistocleis samples (tree rooted in E. araios). Numbers on branches are SH-aLRT/UFBoot support values. Asterisks represent support above 80/95. The terminals of the tree are named as: original labelling of

Figure 3. Geographic location of sampled specimens (symbols) and type-localities of the nominal species (numbers). 1, Elachistocleis araios; 2, E. bicolor (here illustrated as the city of Buenos Aires; see Discussion); 3, E. bumbameuboi; 4, E. carƲalhoi; 5, E. cesarii; 6, E. corumbaensis; 7, E. erythrogaster; 8, E. haroi; 9, E. helianneae; 10, E. magna; 11, E. matogrosso; 12, E. muiraquitan; 13, E. nigrogularis; 14, E. panamensis; 15, E. pearsei; 16, E. piauiensis; 17, E. sikuani; 18, E. skotogaster; 19, E. surinamensis; 20, E. surumu; 21, E. tinigua.