A New All-Female Triploid Species of Gecko and Karyological Data on the Bisexual Hemidactylus frenatus from Vietnam

Abstract

Vietnamese geckos of the genus Hemidactylus, previously considered to belong to the triploid all-female species H. garnotii Dumeril and Bibron (n = 23; 3n = 70), prove instead to belong to the new triploid all-female species H. vietnamensis (n = 20; 3n = 60). It is suggested that H. karenorum Theobald from Vietnam and Burma, seemingly closely related to H. vietnamensis, is also an all-female species. The new species is markedly different in morphology. Neither kary- ological nor electrophoretic analyses support the origin of H. vietnamensis by hybridization among the sympatric bisexual species H. bowringii Dumeril and Bibron, H. frenatus Dumeril and Bibron and Cosymbotus platyurus (Schneider). H. frenatus from Vietnam has a diploid number of 2n = 40. The number obtained is the same as the 2n number of H. frenatus from Australia, but distinct from the number in this species from Taiwan (2n = 46). The genus Hemidactylus includes some 70 mainly tropical species with numer- ous subspecies; it includes the taxonom- ically most diverse group of geckonid lizards. Until recently only H. garnotii was considered to be an all-female species. The studies of Kluge and Eck- ardt (1969) showed that this species in- cludes only females throughout its range and previous reports of males were in error. Hawaiian specimens of H. garnotii proved to be parthenogenet- ic and triploid with a chromosome for- mula of 3n = 70. Based upon an analogy with the known cases of triploidy in some all-female species of lizards of the genus Cnemidophorus (Wright and Lowe, 1967, 1968) might lead to the assump- tion that initially this species became polyploid by interspecific hybridiza- tion. This assumption, however, is un- likely, because no other species of Hemidactylus inhabits Hawaii in sym- patry with H. garnotii. However, there can be no question that the species was introduced to Hawaii for a second time, apparently accidentally by man (Kluge and Eckardt, 1969). Therefore, a key to the problem of the origin of H. garnotii requires comparative karyological and electrophoretic investigations from other parts of its range and primarily from continental areas, where this species is sympatric with several other members of the genus Hemidactylus. The field observations carried out by I. S. Darevsky in 1982 in Vietnam have shown that Hemidactylus garnotii is sym- patric with three other species of the group of house geckos, primarily with H. frenatus. The ratio of occurrence of the former and latter in various popu- lations was about 3:1. Apart from H. fre-