Spalerosophis Research Articles

Blood parasites of amphibians and reptiles in Israel

ABSTRACT A survey of 196 amphibians and reptiles (39 species) from Israel, conducted between June and November, 1984, revealed the following blood parasites: Rana ridibunda, 3 species of Trypanosoma, including T. rotatorium and 2 unidentified species, and 2 unidentified species of Haemogregarina. In lizards and snakes, only haemogregarines were seen, probably Hepatozoon spp. Two species were observed in Agama stellio, probably 2 species in Acanthodactylus boskianus and one species in Varanus griseus. Among the snakes, gamonts of morphologically similar haemogregarines were recorded from Coluber rhodorachis, Malpolon moilensis and Cerastes cerastes. These parasites resembled Hepatozoon aegypti which occurred in 2 specimens of Spalerosophis diadema. A different haemogregarine was observed in Walterinnesia aegyptia. A haemogregarine was recorded from the Caspian terrapin, Mauremys caspica rivulata. Localities and prevalence data are presented and potential vectors for the parasites are discussed.

HEAD TRIANGULATION IN TWO COLUBRINE SNAKES: PROBABLE BEHAVIOURAL REINFORCEMENT OF BATESIAN MIMICRY

ABSTRACT Two Israeli aglyphous colubrid snakes seem to mimic venomous viperid snakes. Spalerosophis diadema cliffordi resembles sympatric desert viperids, especially Vipera persica fieldi, in girth, coloration and defensive behaviour. Coluber ravergieri nummifer resembles the sympatric Vipera palaestinae in length, coloration and defensive behaviour. Direct evidence of functional mimicry is absent, except that man is frequently misled. Because several conventional conditions are fulfilled, these appear to be two cases of Batesian mimicry. Any of five hypotheses may enable the evolution of such mimicry systems in which the model may be lethal. Some individuals of both mimic species greatly increase the morphological resemblance to the models by behaviourally flattening and triangulating the head in the defensive display. This behaviour is distinct from that of flattening the head as part of a general flattening of the body, to increase the area shown an enemy or in basking. Parallely, cobras are mimicked b...