Elachistocleis pearsei (Ruthven, 1914)

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

The status of Elachistocleis pearsei , E. surinamensis , E. sikuani and E. tinigua

Elachistocleissurinamensis and E. pearsei aretheoldest available names in this group. The former was named by Daudin (1802) as Bufo surinamensis , and the latter was named by Ruthven (1914) as Hypopachus pearsei . Both were considered synonyms of Elachistocleis ovalis by Parker (1934). Dunn (1944; 1949) commented on H. pearsei under the new combination Elachistocleis pearsei . Carvalho (1954) placed it into the new genus Relictivomer Carvalho, 1954 based on the presence of the posterior part of the prevomer and, recently, de Sá et al. (2012) reallocated it into Elachistocleis based on DNA data. Kenny (1969) redescribed E. surinamensis from specimens from Trinidad and cited a personal communication from A. Grandison, who had found no differences between specimens of E. surinamensis from Trinidad and a paratype of E. pearsei . Duellman (1997) also compared specimens of E. pearsei from Panama and specimens of Elachistocleis sp. from Gran Sabana, south-eastern Venezuela (which he did not assign to any species, but which falls in the range of occurrence of E. surinamensis ; see Fig. 3 ) and did not find any noticeable difference in the external morphology of adults or in their advertisement calls. Jowers et al. (2021) recently redescribed and designated a neotype for E. surinamensis from Trinidad but, unfortunately, provided no comparisons of the species with E. pearsei .

While the present paper was in review, two new species from Colombia were described and named: Elachistocleis sikuani and E. tinigua (AcostaGalvis et al., 2022) . Although we did not access the vouchers and did not include the new sequences generated therein in our analyses, we confirmed that two lineages already represented in our tree correspond to them (based on genetic similarity, 99.8%). The authors made a brief comparison of the new species with E. pearsei and E. surinamensis , mentioning some differences in body size, quantity and colour of the blotches in live specimens, degree of conspicuousness of the post-commissural glands and presence/absence of the mid-dorsal white line ( Acosta-Galvis et al., 2022). The latter feature was reported as absent in E. sikuani and E. tinigua but present (‘evident’) in E. surinamensis . However, as mentioned above in discussion about the variation of E. surumu , the presence of a mid-dorsal white line in E. surinamensis was not reported in its original description (see: Daudin, 1802) or in its redescription and neotype designation (see: Jowers et al., 2021). On the contrary, Jowers et al. (2021) used the absence of the mid-dorsal line in E. surinamensis to distinguish it from E. nigrogularis . We also have not observed a mid-dorsal white line in any examined specimens of E. surinamensis ( Fig. 1 ).

Acosta-Galvis et al. (2022) did not provide a comparison between E. pearsei and E. surinamensis . Instead, they added more pieces to the puzzle by giving new names to two allopatric lineages. They followed the prevailing tradition in the taxonomy of Elachistocleis of creating more and more nomina rather than conducting a thorough review addressing the validity and application of available names. We reiterate that a comprehensive morphological revision of Elachistocleis is needed and should take priority over the naming of additional new Elachistocleis species. Unfortunately, our sampling of specimens of those species is limited, and a reassessment of the taxonomic status of those species is beyond the scope of the present work. Therefore, for time being, we recognize E. pearsei , E. surinamensis , E. sikuani and E. tinigua as valid species.

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.