Comparative analysis of the integument of different tree frog species from Ololygon and Scinax genera (Anura: Hylidae)

Short-term effects of α-melanocyte-stimulating hormone in three distinct melanin-pigmented cell types of Anura

Ectothermic animals present melanin-containing cells in their integument and viscera. Besides cutaneous melanophores, amphibians have melanomacrophages in the hepatic parenchyma and melanocytes in the viscera, which are also present in their testicular stroma. The native melanocyte stimulating hormone (α-MSH) is the main hormone that modulates the color change in melanophores. However, we still know too little about how the α-MSH acts in vivo on visceral melanin-containing cells. In this study, we collected 30 adult males of Physalaemus nattereri (Anura, Leptodactylidae) to evaluate the short-term effects of α-MSH on melanophores, melanocytes and melanomacrophages under light microscopy. For this, we injected 0.05 ml of a single intraperitoneal dose containing 2.5x10-7 mmol/10g of α-MSH, diluted in ringer solution, in five experimental groups with five individuals each one. The different groups were analyzed after 1, 3, 6, 12 and 24h. The control group with five other individuals received only 0.05 ml of ringer solution. The skin pigmentation increased quickly after animals received the hormone α-MSH with the consequent darkening of the body (body darkness). Melanophores, melanocytes and melanomacrophages responded similarly to the test, with an increase in the area containing melanin. However, melanophores and melanomacrophages reached their darkest pigmentation in a shorter period of time in comparison to the testicular melanocytes, probably due to specific metabolic characteristics of each organ. Thus, we verified that the three types of cells, although present in different organs, are responsive to the native hormone α-MSH, which enables us to treat them as a pigmentary system.

Do host habitat use and cospeciation matter in the evolution of Oswaldocruzia (Nematoda, Molineidae) from neotropical amphibians?

The genus Oswaldocruzia Travassos, 1917 includes approximately 90 species that are parasitic on amphibians and reptiles around the world, of which 43 occur in the neotropical region. However, molecular data supporting the taxonomic status of most species of the genus are scarce, and their phylogenetic relationships remain unknown. Using specimens of four molineid taxa (Oswaldocruzia belenensis Santos, Giese, Maldonado Jr. and Lanfredi, 2008; Oswaldocruzia chabaudi Ben Slimane & Durette-Desset, 1996, Oswaldocruzia chambrieri Ben Slimane & Durette-Desset, 1996 and Kentropyxia hylae Feitosa, Furtado, Santos and Melo, 2015) from amphibian hosts collected in different regions of Pará, Brazil, we conducted morphological studies, molecular analyses and phylogenies (maximum likelihood and Bayesian inference) using the cytochrome c oxidase subunity I (Cox1) gene. The newly generated sequences were compared with those of ten publicly available Cox1 sequences of Oswaldocruzia from Mexico. Our findings demonstrated significant differences between the sequences of amazonian specimens and sequences from specimens collected in Mexico, and we suggest that host-parasite cospeciation or habitat use might be related to molineid evolution in amphibian hosts. Additionally, this work presents new hosts and new geographical records for species of Oswaldocruzia from the neotropics.

Anuran's habitat use drives the functional diversity of nematode parasite communities

Understanding the processes responsible for structuring communities has been a challenge in ecology, and parasite communities are an excellent system to address this issue. The use of different diversity metrics can help us to understand the determinants of the structure of parasite communities, and in this sense, functional diversity indexes make it possible to measure the variability of organism traits in communities. In this study, we investigate how host body size and habitat use influence the functional diversity of nematode parasite infracommunities. We collected and examined 213 individuals of 11 species of anurans in an area of the Brazilian Atlantic Forest, calculated Rao's quadratic entropy as a measure of functional diversity of parasite infracommunities, and tested if this index was related to host body size and habitat use with an analysis of covariance (ANCOVA). Anuran species varied in body size (from 1.80 to 10.35 cm) and habit use (arboreal, terrestrial, and semiaquatic), and in the functional diversity of parasite infracommunities (Rao's quadratic entropy ranged from 0 to 0.196). We observed that anurans with larger body size and terrestrial habit showed significantly greater functional diversity of parasites. We conclude that anuran characteristics drive the functional diversity of nematode parasite communities, and highlight the importance of using different diversity metrics to understand the determinants in the host-parasite interaction.

Parque Nacional da Serra dos Órgãos: the highest Amphibian diversity within an Atlantic Forest protected area

Abstract: We studied the amphibian community of the Parque Nacional da Serra dos Órgãos (PARNASO) for over thirty years. The area of 20,024 hectares has a steep altitudinal gradient (200-2,263 m a.s.l.), and it is located in the municipalities of Guapimirim, Magé, Petrópolis and Teresópolis, middle of the state of Rio de Janeiro, Brazil. Most data were obtained from sampling sites in the municipality of Teresópolis, with additional data from zoological collections and bibliography. We recorded 83 amphibian species distributed in two orders, Anura, 13 families: Aromobatidae (1), Brachycephalidae (11), Bufonidae (5), Centrolenidae (2), Craugastoridae (2), Cycloramphidae (8), Hemiphractidae (7), Hylidae (28), Hylodidae (6), Leptodactylidae (5), Microhylidae (1), Odontophrynidae (3), Phyllomedusidae (3) and Gymnophiona, one family: Siphonopidae (1). In addition, we present six species that occurs in the buffer zone. Ten of these species are endemic of the park, 18 have PARNASO as its type locality, and five the type locality is at the buffer zone.

The sexual dimorphic inguinal glands of the frog species Ololygon centralis (Anura: Hylidae) at light and transmission electron microscopy

The anuran skin characteristically has different types of glands, most of which are microscopic and are spread throughout the skin. Some species have specialized regions where glands agglomerate, forming macroglands. The description of the external morphology of Ololygoncentralis (Pombal & Bastos, 1996) revealed the presence of an inguinal gland. Ololygoncentralis is the only species of the genus that has a macrogland. The present study found these inguinal macroglands to be present only on male specimens, thus characterizing it as a sexually dimorphic skin gland. Microscopic analysis revealed that these glands are composed of many syncytial units involved by myoepithelial cells. The center of the syncytium is full of a proteinaceous secretion with a basic pH and the absence of sugar residues. Similar glands observed in other anuran species have been associated with pheromone production, suggesting that the inguinal glands described for O.centralis males may have a similar function.