Hotspot of tadpole abnormality in suburban south-west Florida

A high concentration of Cuban treefrog (Osteopilus septentrionalis) tadpoles displaying morphological abnormalities was discovered in an untreated swimming pool in Bonita Springs, Florida. This find initiated a 4-year survey (2012-2015) of surrounding roadside drainage ditches that had been treated with insecticide for mosquito control. The study was extended to the populations of Ave Maria, Florida, and Everglades National Park. The core data set of 36,550 tadpoles from the swimming pool and ditches contained 25,136 abnormal tadpoles, an abnormality average of 68.8 %, well above the 5 % minimum definition for a hotspot. The frogs from Ave Maria and the Everglades National park were 0 % abnormal. The type of tadpole abnormality differed between the suburban treated roadside drainage ditches versus the untreated swimming pool, although the same abnormalities were found in both the suburban treated and untreated water. In the untreated swimming pool, 70.1 % of tadpoles displayed abnormalities such as bent tails, abnormal limbs, and disfigured or absent mouthparts. Larvae in the untreated swimming pool metamorphosed en masse despite abnormalities. The high frequency of abnormal metamorph abnormalities found were: kyphosis, scoliosis, microcephaly, and forelimb abnormalities. In the treated roadside drainage ditches, Gosner stage 16-25 tadpoles could not undergo metamorphosis and experienced mass mortality. The abnormalities found at Gosner stage 16 of the embryo were in the head and body. Tadpoles at Gosner stages 19-25 failed to develop gills, were bloated, had growth retardation, and mouthpart abnormalities. The older Gosner stage 25-41 tadpole populations in the ditches showed bloating, lumps, emaciation, and growth retardation. A brief synopsis of O. septentrionalis treefrog biology is also given, including breeding congregations, average 8 hour time to hatching, and 19 days metamorphosis.

Impacto de las variaciones de temperatura diaria en la historia natural de los anuros tropicales

Anuran embryos and tadpoles are daily exposed to wide thermal variations in their ponds, with maximum temperatures at midday. The aim of this research was to study the impact of three daily variable thermal environments (with maximum experimental temperatures between 10:00 and 16:00 hours), on the survival, developmental time and body size of metamorphs of four tropical anuran species from lowland habitats in Colombia. A total of 50 embryos (Gosner stage ten) to metamorphosis (Gosner stage 46) of Rhinella humboldti, Hypsiboas crepitans and Engystomops pustulosus were exposed to each one of the three daily variable temperature treatments: high temperature (mean = 27.5 °C; maximum temperature = 34 ± 1 °C; range = 23-35 °C), medium temperature (25.5 °C; 29 ± 1 °C; 23-30 °C), and low temperature (24 °C; 24 ± 1 °C; 23-25 °C). For the other species, Espadarana prosoblepon, 40 embryos to metamorphosis were exposed to each one of the following thermal treatments: high temperature (mean = 22 °C; maximum temperature = 25 ± 1 °C; range = 18-26 °C), medium temperature (20.5 °C; 22 ± 1 °C; 18-23 °C), and low temperature (19 °C; 19 ± 1 °C; 18-20 °C). For all species, the thermal variable environment with the highest temperature showed the greatest accumulated survival, reduced significantly the developmental time from embryos to metamorphs, and the snout-vent-length of metamorphs. Therefore, under field conditions where ponds are exposed to thermally variable environments, the highest temperatures may promote a decrease in the period of time to metamorphosis, and a positive increase for the anuran survival; nevertheless, extreme temperatures were also found in the microhabitat of the species studied, higher than their upper thermal limits reported, which suggest a vulnerable situation for them and other tropical anurans from similar habitats.

Morphological characterization of the gonads of bullfrog tadpoles (Lithobates catesbeianus)

Introduction: This work describes various aspects of early gonadal development of female and male in pre-metamorphic tadpoles (Lithobates catesbeianus) at Gosner stage 25. Materials and Methods: Ovaries and testicles were prepared for routine light microscopy for morphological study and for acridine orange technique fluroescent microscopy for observation of RNA cytoplasm activity. Results: The results showed that female gonads at Gosner stage 25 predominated primary and secondary oogonias, as well as primary, secondary and tertiary oocytes. The developing testicle presented primary spermatogonia (I or A) and secondary spermatogonia (II or B), and as well as primary and secondary spermatocyte. All this cell phases were morphologically characterized and the cell sizes measured. In pre-metamorphic testes the somniferous duct are not developed and the vasa deferentia is opened. Conclusion: At this point, it was possible differentiate ovary from testes does not for the gonadal cells, but for the general anatomy of the organs, being the ovary a spheroid structure and the testicle an elongated tubule.

Blood Cell Profile of the Developing Tadpoles and Adults of the Ornate Frog,Microhyla ornata(Anura: Microhylidae)

Metamorphosis happens to be an important event in the lifetime of amphibians. Our study offers a record of blood cell profile of laboratory reared tadpoles during development and metamorphosis (Gosner stage 26 to 46) and adults ofMicrohyla ornata. The larval erythrocytes were observed to be circular, oval, and elliptical in shape. However, other variations were distinct during the prometamorphic and metamorphic stages. Crenulated erythrocytes showed a pattern of appearance, and the crenulations varied from minute serrations to highly spiked projections. Correlations between the morphometric values of erythrocytes during the larval development were also determined. The leukocyte profile of the tadpoles showed a high percentage of lymphocytes during larval development while the percentage of monocytes, eosinophils, and neutrophils remained high during metamorphosis and were positively correlated with the developing stages. Blood thrombocytes of the tadpoles were small and were found in clusters. Elliptical erythrocytes were the most common in the adult frogs. However, few erythrocytes were also circular in shape. In adults, the percentage of lymphocytes was found to be more in comparison with the other leucocytes, and neutrophils showed various polymorphic forms. Thrombocytes were nucleated and spindle shaped.

Description of the tadpole of Leptodactylus pustulatus Peters, 1870(Anura: Leptodactylidae)

The external morphology and oral disc of the tadpole of Leptodactylus pustulatus Peters, 1870, are described and illustrated for Gosner stage 39. The internal oral anatomy was analyzed with SEM at Gosner stage 36 whereas chondrocranial anatomy is reported for Gosner stage 35. The overall characteristics do not depart from those known for the genus Leptodactylus and they particularly agree for those of the melanonotus species group. The labial tooth row formula is 2(2)/3. Observations are presented that suggest that L. pustulatus engages in larval parental care.

Hatching dynamics and bet-hedging in a temperate frog, Pseudophryne australis (Anura: Myobatrachidae)

Embryonic development to the time of hatching was found to vary within and between clutches of the red crowned toadlet, Pseudophryne australis. Hatching occurred over many developmental stages, from 24 to 36 (modified Gosner stage). The time taken from oviposition to hatching varied from 15 days to 119 days. In order to determine whether hatching is triggered by environmental cues or is constitutive, clutches were held under constant conditions and compared with those held under conditions similar to the field. Hatching was staggered in all cases implying a constitutive basis. We postulate that this diversification of phenotypes in P. australis is a bet-hedging strategy driven by the unpredictable rainfall conditions within the range of the species. Die Entwicklung der Embryonen des australischen Frosches Pseudophryne australis bis zum Schlüpfen variierte innerhalb und zwischen Gelegen. Das Schlüpfen trat bei vielen Entwicklungsstadien ein. Der Zeitverlauf bis zum Schlüpfen variierte zwischen 15 und 119 Tagen. Gelege wurden unter konstanten Bedingungen gehalten und mit Gelegen in natürlichen Bedingungen verglichen, um festzustellen, ob das Schlüpfen durch Umweltreize angeregt wird, oder ob das Schlüpfen konstitutiv ist. Da das Schlüpfen in allen Behandlungen versetzt war, wird vermutet, dass das Schlüpfverhalten konstitutiv ist. Wir postulieren, dass die Verschiedenartigkeit der Phänotypen bei Pseudophryne australis eine vorbeugende Strategie ist, die durch die nicht voraussagbaren Niederschlagsverhältnisse im Verbreitungsgebiet der Art bedingt wird.