Larval morphology of Amazonia foam-nesting frogs of the genus Engystomops (Anura: Leptodactylidae: Leiuperinae).

The highly differentiated anuran larvae make them an interesting and complementary source of information to understand anuran evolution. Among neotropical foam-nesting frogs, the available information on tadpole morphology for the subfamily Leiuperinae remains largely incomplete and variably reported among genera; in the monophyletic genus Engystomops it is still incipient. Herein, we summarize available information on larval morphology for five of the nine known species of Engystomops, three of them for the first time, reporting external morphology, buccopharyngeal cavity, and skeleton. The tadpoles of the genus have an overall generalized morphology and many traits are conserved across species. Nevertheless, many characters are systematically informative and some are diagnostic for some species, as the paravertebral gland in Engystomops petersi and the dorsally directed spiracle in Engystomops puyango. Other characters provide support for some subclades within the genus. Moreover, some traits, such as the direction of the vent tube, supports the close relationship between Engystomops and Physalaemus, whereas other support the existence of these two as distinct genera, such as the overall shape of the lateral ridge papillae and the presence of a processus pseudopterygoideus.

Tadpole of the Amazonia frog Edalorhina perezi (Anura: Leptodactylidae) with description of oral internal and chondrocranial morphology.

The genus Edalorhina consists of two species of small forest-floor frogs inhabiting the Amazon basin. The tadpole of Edalorhina perezi, the most widely distributed species, was previously described based on a single and early stage (Gosner 25) individual. Herein, we provide a description of the tadpole in Gosner stages 35-36 including internal morphology data (i.e., buccopharyngeal cavity and larval skeleton) based on samples from two populations from Ecuador. Edalorhina shares a generalized morphology with most members of its closely related taxa; however, it is distinguished from the other species by having an almost terminal oral disc. The presence of a dextral vent tube is considered a synapomorphy for the clade consisting of Edalorhina, Engystomops, and Physalaemus. Within this clade, the combination of two lingual papillae, a filiform median ridge, and the lack of buccal roof papillae are diagnostic of E. perezi and putative autapomorphies of Edalorhina. Chondrocranial anatomy provides characteristics, that is, presence of and uniquely shaped processus pseudopterygoideus and cartilago suprarostralis with corpora and alae joined by dorsal and ventral connections that readily differentiates the genus from other Leiuperinae.

Redescription of the tadpole of Leptodactylus natalensis Lutz (Anura: Leptodactylidae), an inhabitant of the Brazilian Atlantic Forest.

The Neotropical foam-nesting genus Leptodactylus Fitzinger is currently composed of 75 species (Frost 2019) divided into four monophyletic species groups (De Sá et al. 2014). The L. melanonotus species group includes 17 species delimited by five adult osteological character-states (De Sá et al. 2014). Leptodactylus natalensis Lutz is the only species of the L. melanonotus species group that occurs in north of the Brazilian Atlantic Rain Forest (De Sá et al. 2014; Almeida et al. 2016) and whose type locality is the municipality of Natal, state of Rio Grande do Norte, Brazil (Lutz 1930). The tadpole of this species was briefly described by Oliveira Lírio-Júnior (2000) based on a single individual from the municipality of Aracaju, state of Sergipe, Brazil. Herein, we present a complete redescription of the tadpole of this species, including morphometric data and interpopulational variation. Besides, we provide comparisons with all members of the L. melanonotus group.