Diego A. Barrasso

Vocal sac development and accelerated sexual maturity in the lesser swimming frog, Pseudis minuta (Anura, Hylidae).

Sexual maturity involves the differentiation of the reproductive system, the maturation of germ cells, and the development of secondary sexual characteristics. Even though this topic has received much attention, little is known about the sequence of events that encompass reproductive maturation in anurans and what it could reveal about the developmental basis of life cycle evolution. The discovery of froglets of Pseudis minuta with incipient vocal sacs calling in breeding pools alongside several larger adult specimens with fully developed vocal sacs raised the question of the timing of sexual maturity in this species. Here we describe the sequence and timing of differentiation, development and maturation of the vocal sac apparatus and the testes in P. minuta (Anura, Hylidae), in order to establish a timeline of events leading to sexual maturity. Differentiation of the vocal sac apparatus begins at the final metamorphic stages, earlier than reported for other species, and the vocal sac acquires its final shape during the early postmetamorphic period. These modifications occur after gonadal differentiation, which begins early during the larval period and proceeds with a highly accelerated rate of development (e.g., secondary spermatids appear well before metamorphic climax), a situation reported previously for other anuran species only in the genus Pseudis. These results, together with a skeletochronological analysis showing that some calling specimens presented no lines of arrested growth, indicate acceleration in the timing of sexual maturity in Pseudis, and raise questions about the interdependence/decoupling during the development of the different components involved in reaching the adult stage.

Stereotyped Defensive Behaviours in Frogs of the Genus Odontophrynus (Amphibia: Anura: Odontophrynidae)

Abstract: Observations on stereotyped defensive behaviours are presented for 7 frog species of the Neotropical genus Odontophrynus from Argentina and Uruguay. Seven stereotyped postures were observed, among which the most common observed were puffing up the body, contracting, and crouching down. Newly reported behaviours include tongue protrusion, eye protection, and some combinations of postures. We provide an account of defensive behaviours already described in Odontophrynus and discuss the correspondence between the terminology used by previous authors and recently proposed classifications. In addition, we highlight defensive mechanisms associated with the body raising posture in Neotropical anurans, which may include intimidating predators, body shape disruption, warning signaling, and exposure of skin macroglands.

Eye ontogeny in P leurodema bufoninum: A comparison with P leurodema somuncurense (Anura, Leptodactylidae): VOLONTERI et al.

Vision is one of the main sensory systems in amphibians, and the eye structure is highly associated with habitat conditions. The ontogeny, as well as the adult structure, of the eye has been studied in only a few species. The life change after metamorphosis is accompanied by changes in the visual environment. The aim of this work is to describe the eye ontogeny of Pleurodema bufoninum and to compare it with that of Pleurodema somuncurense. Specimens of both Pleurodema species were processed for histology analysis at different stages of development, including the tadpole, postmetamorphic, and adult forms. Eyes in both Pleurodema species are composed of the 3 tunics, tunica fibrosa, tunica vasculosa, and tunica interna, and the lens. Additionally, in both, the iris presents a projection on its dorsal and ventral free ends that screens the cornea. This structure has been reported in the eye of several anuran species and is called the umbraculum, meniscus or pupillary nodule. Our results show that the structures related to light capture (retina and lens) appear early in larval life, while the components of the terrestrial‐life eye (scleral cartilage, specialized cornea, eyelids, nictitating membrane, and Harderians gland) do not develop until the metamorphic climax, when the tadpole leaves the water. The adult eyes of P. bufoninum and P. somuncurense are very similar in structure and development.

Internal features of larvae belonging to two species of Pseudopaludicola (Anura: Leiuperinae)

We described the buccal cavity, chondrocranium, and cranial muscles in tadpoles of two species of Pseudopaludicola: P. boliviana (P. pusilla species group) and P. falcipes. The two species share states of only three relevant and informative characters: (1) absence of m. levator mandibularis lateralis, (2) absence of m. levator mandibularis externus superficialis at advanced premetamorphic stages, and (3) presence of long lateral arena papillae of both the roof and floor of the buccal cavity. The larvae of P. falcipes is diagnosed by (states of P. boliviana between parentheses): (1) three lingual papillae (four), (2) one-two pairs of short and blunt infralabial papillae (single pair of multifid papillae), (3) low median ridge (tall), (4) distal connection between pars corpora and pars alaris of the cartilago suprarostralis present (absent), and (5) m. subarcualis rectus II-IV inserted at ceratobranchiale I (ceratobranchiale II insertion). The combination of a processus pseudopterygoideus together with proximal and distal connections on the cartilago suprarostralis occurs in most species of Pleurodema as well. Absence of m. levator mandibularis lateralis is also known for Physalaemus fernandezae and absence of m. levator mandibularis externus superficialis at advanced stages of development (Stage 39 onward) is shared with Edalorhina perezi and Pleurodema diplolister.

External Morphology, Chondrocranium, Cranial Muscles, and Buccopharyngeal Features of Tadpoles of Pleurodema thaul (Anura: Leiuperidae): a Comparison with P. bufoninum

Abstract This article describes the external and buccopharyngeal morphology, chondrocranium, and cranial muscles in tadpoles of Pleurodema thaul from Argentina. Further comparison was made with larvae of other Pleurodema species, particularly P. bufoninum. The larvae of P. thaul possess: (1) tooth row formula 2(2)/3(1), (2) single to double row of marginal papillae with wide rostral gap, (3) presence of long processus pseudopterygoideus, (4) pars alaris and pars corpora of the cartilago suprarostralis joined by both proximal and distal connections, and (5) larval processus oticus present. In the light of the available evidence, the larvae of Pleurodema are characterized by (1) medium size (total length  =  35.4–48.7 mm); (2) medium-sized tail (0.63 times of total length); (3) rounded snout; (4) nostrils closer to the eyes than to the snout; (5) vent tube opening medial; (6) tail tip rounded; and (7) oral disc subterminal with angular constrictions and rostral gap present. In Leiuperidae, the cartilaginous distal connection between pars alaris and pars corpora of the cartilago suprarostralis is present only in Pleurodema. In addition, all Pleurodema studied to date have processus pseudopterygoideus (shared with Eupemphix and Physalaemus marmoratus). Finally, within Pleurodema, the larval processus oticus is present only in P. thaul and P. bufoninum.