The Tadpole of Zachaenus Carvalhoi Izecksohn, 1983 (Anura: Cycloramphidae)

Abstract

The genus Zachaenus Cope is the least specious within Cycloramphidae, including two species: Z. carvalhoi Izecksohn, and Z. parvulus (Girard). Both are leaf litter species distributed across Atlantic forest remnants in Southeastern Brazil. Zachaenus carvalhoi occurs westerly in the states of Espírito Santo and Minas Gerais, and Z. parvulus easterly in the states of São Paulo, Rio de Janeiro, and Espírito Santo (Verdade et al. 2009; Motta et al. 2010; Salles & Maciel 2010; Oliveira et al. 2012; Guedes et al. 2019; Frost 2019). Both species build terrestrial nests, and larval development is endotrophic nidicolous (reproductive mode 21 after Haddad & Prado 2005; Lutz 1944; Thibaudeau & Altig 1999; Zocca et al. 2014). In this work, we describe the tadpoles of Z. carvalhoi, and discuss morphological aspects regarding other endotrophic tadpoles.

Shape Evolution in Two Acts: Morphological Diversity of Larval and Adult Neoaustraranan Frogs

“…data). In fact, reduction in typically larval features, like that reported in several endotrophic lineages, e.g., [43,44,[73][74][75], concerns individual characters (e.g., spiracle and oral disc morphology and keratinization) that do not affect the overall streamlined body shape, e.g., [28,76]. As hinted by the high rate of shape/size variation, significant static allometry appears to be related to ecomorphological diversity in these tadpoles, with a trend of endotrophic tadpoles being smaller and slightly less flattened than semiterrestrial larvae.…”

“…In turn, tadpoles of most species are semiterrestrial, dwellers of wet rocks and rivulets, and characterized by a distinct, streamlined body shape, e.g., [22][23][24][25][26]. Ten species exhibit endotrophic nidicolous development, whereby a free-living, non-feeding larval stage occurs coupled with some anatomical modifications [28].…”

The tadpole of an insular population of Cycloramphus boraceiensis Heyer, 1983 (Anura: Cycloramphidae) with a review of larval descriptions for species in the genus

“…Externally, the tadpole of C. boraceiensis shares features with all the exotrophic tadpoles known for the species in the genus, and with other members of exotrophic Cycloramphidae (e.g., meniscus, abdominal flap, compressed jaws sheaths, size, morphology, and position of the spiracular opening, smaller keratodonts on P3). Recognition of these features are scattered in the literature (Bokermann, 1965;Heyer, 1983a, b;Wassersug & Heyer, 1983;Lima et al, 2010;Da Silva & Ouvernay, 2012Nunes-de-Almeida et al, 2016Almeida-Silva et al, 2019;Moura et al, 2019;Verdade et al, 2019). The value of some of these features for the systematics of the family, observed in tadpoles, as the presence of meniscus on the upper iris, has only recently been recognized (Colaço et al, 2020).…”

“…Larger samples of this species and of other species considered endotrophic, similar to the larvae of the two species of Zachaenus (B. Lutz, 1944;Almeida-Silva et al, 2019) are needed for further investigations. In summary, all exotrophic tadpoles of species of Cycloramphus must have one spiracle that does not form an external tube, and researchers must strive further to properly observe this structure.…”