The poverty of adult morphology: Bioacoustics, genetics, and internal tadpole morphology reveal a new species of glassfrog (Anura: Centrolenidae: Ikakogi) from the Sierra Nevada de Santa Marta, Colombia

The remarkable larval morphology of Rhaebo nasicus (Werner, 1903) (Amphibia: Anura: Bufonidae) with the erection of a new bufonid genus and insights into the evolution of suctorial tadpoles

Tadpoles serve as crucial evidence for testing systematic and taxonomic hypotheses. Suctorial tadpoles collected in Guyana were initially assigned to Rhaebo nasicus through molecular phylogeny. Subsequent analysis of larval and adult morphological traits revealed synapomorphies within the clade encompassing R. nasicus and R. ceratophrys, prompting the recognition of a new genus described herein as Adhaerobufo. The new genus is distinguished from other bufonids by specific phenotypic traits including an enlarged, suctorial oral disc with distinct papillae arrangements, and the presence of certain muscles and narial vacuities at the larval stage. However, only a few adult external characteristics (e.g., enlarged eyelids, infraocular cream spot), seem to be reliably discriminative from related genera. This study underscores the significance of larval morphology in anuran systematics and offers new insights into the evolution of suctorial and gastromyzophorous larvae within bufonids.

A hundred-year-old mystery-the reproductive mode and larval morphology of the enigmatic frog genus Allophryne (Amphibia; Anura; Allophrynidae)

Frogs of the Allophrynidae are an enigmatic family from South America. To date, published information is lacking regarding this group's reproductive biology and larval morphology. Here, we provide the first detailed description of the reproductive mode, developmental mode, and tadpole morphology for Allophryne ruthveni. We developed a captive breeding and rearing protocol for this species and then conducted a series of observations to describe aspects of its reproductive biology. In captivity, this species exhibits aquatic oviposition, where single eggs are laid ungrouped within a simple jelly capsule and are scattered free in the water column before sinking to develop on benthic substrates. We did not observe parental care nor any parental interactions with eggs post-fertilization. Tadpoles are characterized by an oval body, anteroventral oral disc, a labial tooth row formula of 2(2)/3, and a dextral vent tube. The buccopharyngeal cavity is marked by the presence of two pairs of infralabial papilla and four lingual papillae. Cranial morphology is characterized by the presence of the commissura quadratoorbital. This species possesses an additional slip of the m. rectus cervicis and of the m. levator arcuum branchialium III. We discuss our results in comparison with glassfrogs (Centrolenidae).

Harlequin frog tadpoles-comparative buccopharyngeal morphology in the gastromyzophorous tadpoles of the genus Atelopus (Amphibia, Anura, Bufonidae), with discussion on the phylogenetic and evolutionary implication of characters

The Neotropical genus Atelopus is the most diverse genus of bufonids comprising 99 species. Tadpoles of these frogs are readily distinguished based on the presence of a belly sucker, used by them to stay attached to rocks in fast-flowing streams. Despite their intriguing biology, information about their anatomy is scarce and many morphological systems are unknown. We describe the buccopharyngeal cavity of five Atelopus species. The Atelopus buccopharyngeal cavity is characterized by (1) presence of a pendulum-like papillae in the prenarial arena, (2) presence of a glandular zone in the prenarial arena, (3) narial vacuities, (4) conical median ridge, (5) absence of buccal roof arena papillae, (6) absence of buccal roof pustulations, (7) single pair of infralabial papillae, (8) absence of lingual papillae, and (9) absence of pustulations in the buccal floor. We propose that characters 1, 2, and 3 are new synapomorphies for the genus. We also propose that the presence of a single pair of infralabial papillae is a synapomorphy for bufonid. Finally, we discuss the convergent evolution of gastromyzophorous and suctorial tadpoles withing anurans.

A multidisciplinary approach reveals a new species of glassfrog from Colombia (Anura: Centrolenidae: Nymphargus)

Anurans of the family Centrolenidae are a highly diverse clade of Neotropical treefrogs. In the last two decades, glassfrogs have become a model system for studies in ecology and evolutionary biology, in part because their taxonomy and phylogenetic relationships are considered relatively well established. However, there are still many gaps in our knowledge, for example, which morphological characters are important for species delimitation. Consequently, several species complexes in Centrolenidae remain unresolved. Using data on external and internal morphology of adult individuals, tadpoles, advertisement call traits and genetic sequences, we describe a new species of glassfrog (Nymphargus pijao sp. nov.) endemic to Colombia that has been previously missasigned to Nymphargus griffithsi. We include in this description data of three phenotypic characters related to pectoral musculature and testis size, which have been traditionally overlooked in studies about the taxonomy and systematics of glassfrogs. In addition, we present details of a low-cost method implemented in the field to rear tadpoles of the new species. This methodology can solve common problems during the management and care of glassfrogs egg masses and tadpoles, and hence, promotes their description for more species and a better knowledge of the anuran biodiversity in Neotropics.

The missing piece of the puzzle: larval morphology of Xenohyla truncata (Anura: Hylidae: Dendropsophini) and its implication to the evolution of Dendropsophini tadpoles

Dendropsophini is a highly diverse clade with a controversial phylogenetic and taxonomic history. Different generic arrangements have been proposed and the monophyly of several clades supported or rejected. Previous evidence suggested that larval morphology could play an important role in our understanding of the evolution and diversification of Dendropsophini, although data are missing for most lineages, including the sister group of Dendropsophus, Xenohyla. Herein we describe the internal morphology of the tadpoles of X. truncata and compare our results with available information for members of Dendropsophini and closely related lineages. We propose that the presence of a fan-like papilla in the buccopharyngeal cavity, a single element suprarostral, and a triangular process at the base of the muscular process are synapomorphies for Dendropsophini; moreover, the presence of a divided m. subarcualis rectus II–IV seems to be a synapomorphy for Pseudini and, the nasal sac insertion of the m. levator lateralis could be a synapomorphy of Dendropsophini + Pseudini.

Anatomical features of the phytotelma dwelling, egg-eating, fanged tadpoles of Rhacophorus vampyrus (Anura: Rhacophoridae)

Tadpoles of the Vampire tree frog Rhacophorus vampyrus differ substantially from other rhacophorid tadpoles, by having profound modifications in external morphology. The morphological peculiarities of this species likely correlate with their arboreal microhabitat and strict oophagous diet. In this work, we examine buccal and musculoskeletal anatomy and compare them to other rhacophorid and egg-eating larvae. The shape and arrangement of cartilages of the lower jaw are unique among tadpoles, and the lack of a palatoquadrate suspensorium is only known in the distantly related macrophagous tadpoles of the dicroglossid Occidozyga baluensis. The cranial musculature is massive, and the morphology of several mandibular, hyoid, and abdominal muscles could be related to the ingestion and transit of large eggs. In the buccal cavity, conspicuous aspects are the absence of ridges and papillae, and the development of a unique glandular zone in the buccal floor. Finally, observations of the skeletal support of keratinized mouthparts allow us to present a topography-based hypothesis of homology of the conspicuous fangs of these tadpoles.

The remarkable larval anatomy of Proceratophrys minuta Napoli, Cruz, Abreu and Del-Grande, 2011 (Amphibia: Anura: Odontophrynidae)

The free living larvae of anurans (i.e., tadpoles) are a key element in the evolution and diversification of this group, and as such, their morphology is an important element to understand the phylogenetic relationships of frogs. However, the lack of data on larval morphology prevents us from fully understanding larval evolution in several lineages. The Neotropical genus Proceratophrys currently comprises 39 species, but descriptions of the internal morphology of larvae in this group are rare and restricted to few aspects of their buccopharyngeal cavity, chondrocranium, and muscles. In the present study, I describe the internal anatomy of the tadpole of P. minuta and report a new remarkable myological character state for the species. Given the rarity of this material, the description of this species' buccopharyngeal and musculo-skeletal elements is based on two tadpoles in developmental stages 30 and 31. Several new apomorphic character states are described: (a) the presence of a conical papilla in the interior of the nostril; (b) a row of five short, conical papilla preceding the tall, postnarial papilla; and (c) the m. mandibulolabialis inserting in the gular skin. This latter feature is a remarkable, newly discovered character state that had never been reported in the literature before and is probably related to a particular feeding habit of the tadpoles of this species. The function of the m. mandibulolabialis in P. minuta is unknown.

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.