Eduardo A. Sanabria

A New Phymaturus (Iguania: Liolaemidae) from the Southern Extreme of the Argentine Puna

We describe a new species of Phymaturus from the Sierra La Invernada of San Juan Province, Argentina. The new species shares the apomorphies of the P. palluma group including a fragmented subocular, square nonimbricate superciliaries, rugose and strongly mucronate dorsal caudals, and a midvertebral band of enlarged scales. Within the P. palluma group, the new species can be assigned to the Puna clade, with which it shares a dorsal pattern of small, dispersed brown spots and lack of black reticulations. The new species differs from other members of the Puna clade in several aspects of squamation and body pattern and color. Most notably, the new Phymaturus has a conspicuous yellow scapular spot, lacks a vertebral stripe, and has incomplete dark pigmentation over the dorsal neck. The new species is known only from the region of the type locality, the southernmost (and geographically isolated) extent of the Puna phytogeographic province, where it occurs at high elevations (>3100 m). We provide information on aspects of the natural history, diet, thermal biology, and apparent parental care exhibited by females of the new species. Describimos una nueva especie de Phymaturus de la Sierra La Invernada de la provincia de San Juan, Argentina. La nueva especie comparte las apomorfías del grupo P. palluma incluyendo una subocular fragmentada, superciliares cuadrangulares no imbricadas, escamas caudales dorsales rugosas y muy mucronadas y una banda mediovertebral de escamas agrandadas. Dentro del grupo P. palluma, la nueva especie se asigna al clado Puna, con el que comparte un patrón dorsal de pequeñas y dispersas manchas marrones y la falta de reticulaciones en negro. La nueva especie se diferencia de otros miembros del clado Puna en varios aspectos de la escamación y el patrón de cuerpo y color. Lo más notable en el nuevo Phymaturus es una mancha escapular amarilla, carece de una franja vertebral, y tiene pigmentación oscura incompleta sobre el dorso del cuello. La nueva especie es conocida sólo de la región de la localidad tipo, la más meridional (y geográficamente aislada) extensión de la provincia fitogeográfica de la Puna, donde se encuentra a gran elevación (>3100 m). Proveemos de información sobre aspectos de la historia natural, la dieta, la biología térmica, y el aparente cuidado parental exhibido por hembras de la nueva especie.

Size- and Sex-Dependent Variation in Diet of Rhinella arenarum (Anura: Bufonidae) in a Wetland of San Juan, Argentina

Abstract We studied body-size and sex-dependent variation in the diet of Rhinella arenarum in a wetland of San Juan, Argentina. We hypothesized that prey size would be positively correlated with toad size and that the guts of larger toads would contain fewer prey items. Toads from this population eat primarily ants and, secondarily, beetles, indicating a feeding strategy that is intermediate between specialist and generalist. This feeding strategy may be influenced by prey availability. Contrary to our expectation, prey size was not related to toad body size, and the relationship between the prey number and toad body size was positive. Our findings, coupled with similar diet studies of toads, suggest geographically widespread phylogenetic conservatism in the diet of bufonids.

First record of partial albinism and scoliosis in Odontophrynus occidentalis tadpoles (Anura: Cycloramphidae)

Albinism has been widely reported for diverse group of vertebrates. However, scoliosis is a rare abnormality. In this work, the first record of partial albinism and scoliosis case in tadpole of the frog Odontophrynus occidentalis is being presented. The individual was captured in Quebrada de las Flores, Sierra Pie de Palo, Caucete Department, San Juan Province, Argentina.

Variation of thermal parameters in two different color morphs of a diurnal poison toad, Melanophryniscus rubriventris (Anura: Bufonidae)

We study the variation in thermal parameters in two contrasting populations Yungas Redbelly Toads (Melanophryniscus rubriventris) with different discrete color phenotypes comparing field body temperatures, critical thermal maximum and heating rates. We found significant differences in field body temperatures of the different morphs. Temperatures were higher in toads with a high extent of dorsal melanization. No variation was registered in operative temperatures between the study locations at the moment of capture and processing. Critical thermal maximum of toads was positively related with the extent of dorsal melanization. Furthermore, we founded significant differences in heating rates between morphs, where individuals with a high extent of dorsal melanization showed greater heating rates than toads with lower dorsal melanization. The color pattern-thermal parameter relationship observed may influence the activity patterns and body size of individuals. Body temperature is a modulator of physiological and behavioral functions in amphibians, influencing daily and seasonal activity, locomotor performance, digestion rate and growth rate. It is possible that some growth constraints may arise due to the relationship of color pattern-metabolism allowing different morphs to attain similar sizes at different locations instead of body-size clines.

Thermal ecology of the post-metamorphic Andean toad (Rhinella spinulosa) at elevation in the monte desert, Argentina.

Rhinella spinulosa is an anuran toad species distributed latitudinal and altitudinal (1200-5000m) from Peru to Argentina, inhabiting mountain valleys in the Andes. Considering the broad range of habitats where they live, it is important to understand the thermal physiological mechanisms, thermal tolerances and physiological adaptations for surviving in rigorous environments. We investigated the thermal parameters (field body temperature, selected body temperature, locomotor performance in field and laboratory conditions, and thermal extremes) during diurnal activity for a population of juvenile, post-metamorphosed toads (Rhinella spinulosa) from the Monte Desert of San Juan, Argentina. Post-metamorphic toads are active from approximately 1100-1900 (in contrast to nocturnal adult toads). Our findings show that these toads have a wide thermal tolerance range, ranging from a critical thermal maximum of 36.9°C to crystallization temperatures below 0°C. During their active period, toads always showed suboptimal thermal conditions for locomotion. Despite the suboptimal condition for the locomotion, diurnal activity is likely to confer thermal advantages, allowing them to search for food and increase digestion and growth rates. We also found that the toads are capable of super-cooling, which prevents mortality from freezing when the environmental temperatures drop below 0°C. The environmental temperatures are below zero at night, when toads are inactive and take refuge under rocks. In summary, this toad population demonstrates high thermal plasticity, as shown by a relatively high level of activity sustained over a wide range of ambient temperature (~35°C). These thermal adaptations allow this species of juvenile toads to inhabit a wide range of altitudes and latitudes.

Thiols of flagellar proteins are essential for progressive motility in human spermatozoa.

Male infertility is a disorder of the reproductive system defined by the failure to achieve a clinical pregnancy after 12 months or more of regular unprotected sexual intercourse. The presence of low-motile or immotile spermatozoa is one of many causes of infertility; however, this observation provides little or no information regarding the pathogenesis of the malfunction. Good sperm motility depends on correct assembly of the sperm tail in the testis and efficient maturation during epididymal transit. Thiols of flagellar proteins, such as outer dense fibre protein 1 (ODF1), are oxidised to form disulfides during epididymal transit and the spermatozoa become motile. This study was designed to determine how oxidative changes in protein thiol status affect progressive motility in human spermatozoa. Monobromobimane (mBBr) was used as a specific thiol marker and disruptor of sperm progressive motility. When mBBr was blocked by dithiothreitol it did not promote motility changes. The analysis of mBBr-treated spermatozoa revealed a reduction of progressive motility and an increased number of spermatozoa with non-progressive motility without affecting ATP production. Laser confocal microscopy and western blot analysis showed that one of the mBBr-positive proteins reacted with an antibody to ODF1. Monobromobimane fluorescence intensity of the sperm tail was lower in normozoospermic than asthenozoospermic men, suggesting that thiol oxidation in spermatozoa of asthenozoospermic men is incomplete. Our findings indicate that mBBr affects the thiol status of ODF1 in human spermatozoa and interferes with progressive motility.

Diet composition of an invasive population of Lithobates catesbeianus (American Bullfrog) from Argentina

The American bullfrog Lithobates catesbeianus has been introduced around the world, with invasive populations reported from almost all South American countries. A population of this species was introduced in the Calingasta department of San Juan province, which is an arid environment in western Argentina. This work provides information on the dietary composition of an invasive population of L. catesbeianus, and compares the degree of dietary overlap between adults and juveniles. Stomach contents of 169 bullfrogs (82 adults and 87 juveniles) were analysed. Adults consumed 40 prey taxa and Hymenoptera (Insecta) was the most numerous prey item (41.8%), followed by Araneae (13.6%) and Aeglidae (13.4%). Juveniles consumed 29 prey taxa and Hymenoptera constituted the highest percentage in prey number (77.2%). The trophic overlap niche index at the same level shows a value of 0.64 overlap in dietary community between adults and juveniles of this bullfrog. Aeglidae was volumetrically the most important trophic item (25.4%), followed by Anura (25.02%). Our results showed that cannibalism in bullfrogs is more common than the consumption of native anurans, coinciding with that reported in other populations of introduced bullfrogs. The high similarity in the diets of both size classes and the association between the size of the predator and prey suggest that the impact caused by bullfrogs throughout their ontogeny is high and probably has an impact on their prey. Freshwater crabs are the main items in the diet of Lithobates catesbeianus in other introduced populations and are usually the most conspicuous at our study site. The crabs in freshwater ecosystems are part of the lowest trophic level in the food chain. The major threats to the southern region’s freshwater crabs include deforestation, farming and exotic species. Lithobates catesbeianus has a generalist diet and high overlap between adults and juveniles.

Patterns of daily and seasonal calling activity of a direct-developing frog of the subtropical Andean forests of Argentina

Climate often regulates different aspects of the life cycle and activity of amphibians. Climatic seasonality may impose severe restrictions on breeding patterns of direct-developing terraranan frogs. We studied the influence of abiotic cues on calling activity of males of the direct-developing frog Oreobates discoidalis in the Yungas forests of north-western Argentina. Vocalization activity and daily emission pattern of the vocal repertoire were registered with a frog-logger, and climatic variables were registered with a data logger. We sampled two reproductive seasons from 2010 to 2011. We used ordinal logistic regression to evaluate the relationship between independent climatic variables and the intensity of calling activity. The calling season of males of O. discoidalis was triggered by the first rainfall of the aestival season. The species could be defined as crepuscular–nocturnal with a calling activity peak at dusk. Sporadic calling activity during day time was associated with conditions of high humidity and rainfall. Both the emission and the intensity of the advertisement call activity were influenced by time of the day, high levels of relative air humidity and presence of rainfall; air temperature was not a determinant factor in the calling activity of this frog species. Territorial calls were strongly associated with full chorus activity that could be associated with a mechanism of inter-male spacing.

Sexual Size Dimorphism and Age in Odontophrynus cf. barrioi (Anura: Odontophrynidae) from the Monte Desert, Argentina

Abstract Current knowledge on sexual dimorphism and population structure in the genus Odontophrynus is limited. We studied age structure, age at maturity, and longevity in Odontophrynus cf. barrioi, with skeletochronology. We also determined whether sexual dimorphism in body size exists in this species, and evaluated its relation to demographic life history traits. We found that females were larger in four variables corresponding to the morphology of the head. In addition, females of O. cf. barrioi have a longer tibia-fibula and femur than males. Nevertheless, Odontophrynus cf. barrioi shows no sexual dimorphism in snout–vent length. We suggest the possibility that sexes have different growth trajectories after the onset of reproduction, as they are exposed to different selection pressures, or even predation rate, because of size differences.

First Survey of Nematode Parasites in Introduced American Bullfrogs (Lithobates catesbeianus) in Argentina

ABSTRACT: We provide the first report of nematode parasites from the introduced American bullfrog (Lithobates catesbeianus) in San Juan Province, Argentina. Sixteen individuals (7 adult females, 6 adult males, and 3 juveniles) of L. catesbeianus were studied. Thirteen (81.3%) of the frogs harbored 2 species of nematodes: larvae of Contracaecum sp. (Nematoda, Anisakidae) in the serosal surface of the stomach wall and at the gastroduodenal junction, and adults of Falcaustra sanjuanensis (Nematoda, Kathlaniidae) in the large intestine. Previous studies of introduced populations of American bullfrogs in Argentina have focused on population structure, trophic ecology, and their impacts on native amphibian and other vertebrate populations. More studies of their parasites need to be conducted in South America in general, and in Argentina specifically, in order to assess the extent to which bullfrogs either introduce new parasites or are infected by native parasites and to determine the potential impacts of nonnative parasites on native frog species.