ISRAEL JOURNAL OF ZOOLOGY, Vol. 37, 1992, pp. 247-249

A MIXED LITTER OF HORNED AND HORNLESS HORNED VIPERS CERASTES CERASTES CERASTES (OPHIDIA: VIPERIDAE)

YUVAL STERER 43 Blauvelt Road, Monsey, New York 10952, U.SA.

The horned viper Cerastes cerastes (Linnaeus, 1758) is famous for a pair of 'horns' (really spine-like scales) above the eyes. Actually, some individuals lack these horns, regardless of sex (Anderson, 1898: 331, 334; Gasperetti, 1988: 339). The species ranges across the sand deserts of northern Africa and southwestern Asia; on both continents, the frequency of occurrence of the horns in the population varies among localities, even at small distances. Populations may be predominantly horned, entirely hornless, or mixed (Schnurrenberger, 1959; Gasperetti, 1988; personal observations). Both Stemmler (1967) and Petzold (1975: 454) made a secondary reference to mixed litters, or possibly the same mixed litter, of horned and hornless C. cerastes. However, Y. L. Werner (personal communication) did not succeed, despite his efforts, in finding the original evidence on which these reports had been based. Gasperetti (1988: 339) commented on C. c. gasperettii, "It is speculative that from the same litter may be individuals either with or without horns." The purpose of this note is to report on such a mixed litter. An adult hornless female C. c. cerastes was received on 4 June 1988 from the Faiyum sands (Lower Egypt west of the Nile) in gravid condition and housed on the author's reptile facility at Petah Tiqwa, Israel. On 14 July 1988 she oviposited seven eggs. These were incubated at a temperature fluctuating between approximately 24 °C at night and 28°C at midday and at a relative humidity approximating 70%. One egg was accidently lost at an early stage; six hatched on 5 Sept. 1988. Two of the hatchlings were homed, and four- hornless (Fig. 1). At the time of writing, the mother is alive and in the author's care, and of the juveniles four are alive: two (one homed, one hornless) in the author's care and two (one homed, one hornless) in the Biological Institute Beit Pinhas, Haifa, Israel. This observation substantiates the notion that homed and hornless C. cerastes can be litter-mates (Gasperetti, 1988) and accords with the reports by Stemmler (1967) and Petzold (1975) to this effect. The incubation period of 53 days at 24-28°C parallels that reported by Marchetti (1967): eggs laid by a female C. cerastes from southern Morocco, were incubated at a temperature fluctuating between 23-25°C at night and 28-30°C by day, and hatched after 48 days. The difference in incubation time is presumably explicable as a temperature effect (Petzold, 1982: 620).

Accepted 15 January 1991 248 Y. STERER Isr. J. Zool.