Elachistocleis ovalis (Schneider, 1799)

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 : 561-562

The (unsettling) status of Elachistocleis ovalis

There has been a long controversy regarding the validity and applicability of this nomen, especially regarding whether it should be applied to immaculate or to maculate-bellied specimens of Elachistocleis [see Lavilla et al. (2003) and Caramaschi (2010) for lengthy discussions on the issue]. While some authors (e.g. Parker, 1927; Dunn, 1949; Kenny, 1969; De la Riva et al., 2000) applied this name to maculate-bellied specimens – thus conveniently distinguishing them from the immaculate-bellied E. bicolor – others did not. In a meeting abstract of his unpublished dissertation, Carcerelli (1992) regarded E. bicolor a junior synonym of E. ovalis ; a view that was followed by a few other authors (e.g. Klappenbach & Langone, 1992; Olmos & Achaval, 1997; Kwet & Di-Bernardo, 1998). That decision was mainly grounded on the fact that Schneider (1799) stated that Rana ovalis had an ‘ inferne flavidus ’ (yellow venter). Lavilla et al. (2003) also remarked that, considering Schneider’s description, E. ovalis should be applied to the specimens with ‘immaculate, yellow, ventral colouration’; but they did not adhere to the idea of synonymizing E. ovalis and E. bicolor . Instead, they regarded E. ovalis as restricted to the ‘northern portion of the generic range’, whereas E. bicolor would be restricted to the ‘southern portion of the generic range’.

Nevertheless, ventral patterns have been recorded idiosyncratically in the literature and ‘uniform’, ‘yellow’ and ‘immaculate’ bellies have often been treated as synonyms, although this is not necessarily the case. Some individuals of typically maculatebellied species can present the venter almost entirely covered by yellow blotches (e.g. Fig. 5G, J, L ) and thus could also fit into the ‘ inferne flavidus ’ description. Thus, assuming that the type of E. ovalis had an immaculate venter, because Schneider (1799) stated that it has ‘ inferne flavidus ’, is not solid reasoning in itself. Moreover, as described above for our samples from Cuiabá ( AAG-UFU 5953 and AAG-UFU 5954 ), sympatric specimens may present different ventral patterns and still be genetically similar, increasing the complexity of this puzzle .

The identity of E. ovalis is still a conundrum, especially difficult to solve due to the lack of a type locality and the unknown whereabouts of the type specimen. For these reasons, among others, Caramaschi (2010) proposed an operational solution: he considered Rana ovalis Schneider, 1799 and the combination Elachistocleis ovalis a nomen dubium associated with a species inquirenda; a decision that was followed by Jowers et al. (2021). Since we could not find any new evidence on the contrary, we also adhere to that decision by Caramaschi (2010).

AmphibiaWeb (2022) and Frost (2022), the two largest amphibian taxonomic catalogues, have essentially also followed this suggestion and, although both still include this species in their list of 22 recognized Elachistocleis species, the following notes are added for E. ovalis : ‘Nominally, Elachistocleis ovalis is a nomen inquirenda (see comment), not applied to a biological population. But, pending revision, this name is applied to populations from Bolivia, although a great deal of confusion surrounds the identification of specimens mentioned from other countries’ ( Frost, 2022); ‘This ancient name (1799) lacks type material and there is no type locality. Despite wide usage it should be considered an invalid name and not used [...] Pending revision, AmphibiaWeb continues to use the name E. ovalis ’ (AmphibiaWeb, 2022).

Figures

Figure 5. Variation of ventral colourpattern among sample vouchersof differentspecies of Elachistocleisof the surinamensis group. A, E. muiraquitan; KU 215552 (image KUDA 013705; photo by Ana Motta). B, E. pearsei; USNM 572735. C, E. sikuani; CFBH 36120. D, E. surinamensis; CAS 257681. E, F, E. cesarii; CFBH, 31875, 38066. G, E. cf. piauiensis 1; URCAH 5474. H, E. cf. piauiensis 2; CFBH 20565. I, E. cf. piauiensis 3; CFBH 16998. J, E. cf. piauiensis 4; CFBH 31629. K, L, E. magna; AAGUFU 5766, 6264. Photos not to scale.