P. Borsa et Jah. Benzie, GENETIC-RELATIONSHIPS AMONG THE TOPSHELLS TROCHUS AND TECTUS (PROSOBRANCHIA, TROCHIDAE) FROM THE GREAT-BARRIER-REEF, Journal of molluscan studies, 59, 1993, pp. 275-284
Large species of Trochus and Tectus common on the Great Barrier Reef w
ere screened for polymorphism at eleven putative allozyme loci. The sa
mples were first identified as belonging to Trochus niloticus L., 1758
, Trochus conus Gmelin, 1791, Trochus maculatus L., 1758 and Tectus py
ramis (Born, 1778), but subsequent electrophoretic analysis showed tha
t Trochus conus and Tectus pyramis each consisted of at least two repr
oductively isolated, sympatric species. Some of these species matched
older descriptions, based on shell morphology, of taxa which had since
been synonymised. Allozyme polymorphism ranged from high in Tectus py
ramis to nearly zero in Trochus maculatus. Average Nei's genetic dista
nce between Trochus species was 1.726. Genetic distance between Tectus
species was 1.510. Nei's genetic distances between Trochus and Tectus
ranged from 3.226 to infinity. A phylogenetic tree based on genetic d
istances grouped together all four Trochus species versus the two Tect
us species, confirming the validity of these two genera erected origin
ally on the basis of shell morphology.