The Herpetological Journal

pp.89-94

Authors: Bruce A. Young, Jackie Solomon And G Eorg E Abishahin

Abstract: As part of its defensive display the Indian rat snake, Ptyas mucosus, mediolaterally compresses the anterior portion of its body and expands its throat region ventrally. During this postural display P. mucosus produces a deep, rumbling defensive growl. Acoustic analysis of this growl revealed it to be a long moderately loud sound dominated by lower frequencies. Binding the neck and anterior portion of the body with surgical tape prevented the postural display; while the defensive sounds produced by bound specimens had the same duration and amplitude, their frequency increased significantly. The tracheal membrane of P. mucosus is unusually wide and expands away from the tracheal rings into the body cavity. We hypothesize that during the defensive postural display the expansive tracheal membrane is collapsed forming isolated pockets which have a resonance effect on the exhalent airstream. Ptyas mucosus may be an acoustic Batesian mimic of the king cobra, Ophiophagus hannah.

Keywords: sound production, acoustics, Batesian mimicry, colubrids, defensive behaviour

pp.95-99

Authors: J. Hoffman And M. R. Warburg

Abstract: The larvae of Pelobates syriacus have a long developmental period to metamorphosis. This is atypical ofxeric-inhabiting anurans and suggests that the populations of this species in Israel are relicts from the time when this region enjoyed a milder climate. In contrast, metamorphic climax is rapid: In the course of a few days the external appearance changes from that of tadpole to toad let. Durmg the same short period, together with other internal reorganizations, the kidney completes its maturation from pronephros to mesonephros. The production of urine, a fluid which is almost identical to plasma in the tadpoles, ceases, and when it is resumed in postmetamorphic toadlets, it is dilute and adult-type with nitrogen as urea replacing ammonia. There is a simultaneous increase in plasma osmolality. In P. syriacus a long period of development followed by the emergence of a relatively large metamorph may be an adaptation to a hostile environment. Coupled with the rapid metamorphic climax , these life history features may increase the opportunities to disperse and burrow into soil that remains moist, at the beginning of a long hot and dry summer.

Keywords: Pelobates, ontogenesis, osmolality, ion-balance, nitrogen excretion

pp.101-110 

Authors: Miguel Vences And Frank Glaw

Abstract: Based on morphological differences, specimens currently attributed to the Malagasy montane frog species Mantidactylus madecassus can be divided into two distinct groups, which correspond to the geographically separated populations from the mountain massifs of Ankaratra and Andringitra. The Ankaratra populations differ from the Andringitra populations by the lack of distinctly bilobed subarticular tubercles on the fingers; more extended webbing between the toes; and a less contrasting dorsal colour pattern. Furthermore, they are distinguished morphometrically. The name Mantidactylus pauliani Guibe, 1974 is available for the Ankaratra specimens and is hereby resurrected. A lectotype of M. madecassus is designated. The two species share a lack of vomerine teeth and both possess a very short snout, and should be considered as closely related allopatric sister taxa. So far as is known, they occur between 1500 and 2500 m altitude (mainly above 2000 m), in brooks and their tributaries in areas of ericoid vegetation or of rock formations with rupicolous plant communities. A short review of Malagasy montane amphibian species is provided, confirming that montane habitat in Madagascar harbours an important diversity of species specialized to high-altitudes.

Keywords: Anura, Ranidae, Mantellinae, Brygoomantis, montane herpetofauna, Madagascar

pp.111-117

Authors: Nora R. Ibargüengoytia 1 And Victor E. Cussac

Abstract: Female Liolaemus elongatus and Liolaemus pictus have biennial and triennial reproductive cycles respectively, with a low availability of reproductive females during the breeding season. Previous results have shown slight interspecific differences in sexual dimorphism between L. pictus and L. elongatus, coinciding with differential accessibility to females. Present results show major interspecific differences in the timing of spermatogenesis. Male L. pictus begin to reproduce during the first year of adulthood and remain active during a long breeding season. In contrast, male L. elongatus delay reproduction for one year and reproduce during a narrower period, in synchrony with the female reproductive cycle. Male L. elongatus showed an increasing testicular size during spermatogenesis, and a reduction in size when the first spermatozoa appear. Liolaemus pictus had spermatozoa in seminiferous tubules for the entire sampling period, from spring to autumn. The existence of severe thermal constraints for vitellogenesis and pregnancy set the following chain of causal events: environmental conditions - female cycle - male cycle and male dimorphic traits. This sequence of events shows how environmental cues can constrain the female cycle, and female availability, and thereby also affect the male cycle and the development of male dimorphic traits.

Keywords: Sexual dimorphism, Liolaemus, male reproductive cycles

pp.119-123

Authors: Dan Cogalniceanu

Abstract: Studies carried out in England on the reproduction of smooth newts have revealed that under relatively constant, favourable conditions, they spend a period of up to six months in the water, with oviposition lasting about 4-6 weeks. The reproductive strategies of two Romanian smooth newt populations inhabiting unpredictable, highly variable and hostile environments were analysed for comparison. Females in both populations had an average body weight at the beginning of the reproductive period of 1 .09 and 0.96 g respectively, one third of the average body weight of adult females in England. The average snout-vent lengths were 34.9 and 33.8 mm, about 25% shorter than those from English populations. The average numbers of eggs deposited by female newts from the two populations were 74 and 51 respectively, compared to an average of 300 eggs in England. The average age of females from one of the populations studied was 4.2 years and age at first reproduction was estimated at three years, similar to another English population studied. At the end of the oviposition period females still contained yolked oocytes, suggesting that clutch size cannot be correctly estimated by counting the initial numbers of yolked ovarian oocytes. Their reproductive effort was reduced since, due to environmental hostility, body size was significantly diminished and this leads to a smaller clutch size.

Keywords: Triturus, newts, reproductive strategies, variable environments

pp.125-132

Authors: Ronald E. Willemsen And Adrian Hailey

Abstract: The area of dark pigmentation on the plastron of the tortoise Testudo hermanni shows a latitudinal cline over about 400 km in Greece, with populations in the south being darker. The carapace did not show the clinal trend, and pigmentation was not significantly related to longitude or altitude. We examined several possible explanations for the cline, including an effect of incubation temperature, random genetic variation, and adaptation to several environmental variables. The most likely explanation is selection for thermoregulation, with decreased dark pigmentation in the north reducing heat loss to the substrate by infra red radiation during activity. This hypothesis was supported by data on body (T_b) and substrate (T, ) temperatures in populations from northern, central and southern Greece. T_b was generally above T, , showing that heat would generally be lost rather than gained through the plastron, and the mean difference T_b -T, was greatest in the north: +6.6 °C, compared to +2.4 °C in the south. Mean T_b was lowest in the south (26.9°C, compared to 29.3°C in the north) and the slope of T_b on T, was about I (compared to 0.5 in the north). Thermoregulation in southern Greece is similar to that of tropical tortoises, with avoidance of overheating being the major problem, rather than elevation of T_b for activity.

Keywords: cline, pigmentation, Testudo, thermoregulation, tortoise