Chromosomes of Arenaria interpres interpres(L.)

Abstract

The diploid number of chromosomes was determined as 80 (_??_2n) in the spermatogonial divisions. The macro-chromosomes include four pairs, being 8 in number. They have a formula consisting of aR+bv+cr+dr. The micro-chromosomes vary in size from small rods to spherulus and are 72 in number.There are found with indisputable clearness 40 bivalents in the primary spermatocyte metaphase plate. Two larger bivalents, probably descendants from the aR and bv elements of the diploid group, are remarkable for their conspicuous configuration.The karyotype as found in this species is quite unique in birds so far studied. In the related species, Charadrius dubius studied by Yamashina (1946), the following choromosome formula was given:Charadrius dubius 2J's+2V's+2R's+4v's+68r's _??_2n=78In comparison with the chromosomes of Arenalia interpres, there is no approach or similarity between the two species. Cyto-taxonomical consideration will be retained until further data can be accumulated.