Chromosomes of two species of Japanese fishflies in the genus Parachauliodes (Megaloptera: Corydalidae: Chauliodinae)

Abstract

We analyzed chromosomes of two species of Japanese fishflies (Megaloptera: Corydalidae: Chauliodinae), Parachauliodes continentalis and P. japonicus. The chromosome numbers in both species were 2n=20 consisting of 9 pairs of autosomes plus XX chromosomes in females and Xy in males. The X chromosomes were subtelocentric while the y was the smallest chromosome of the set. The sex chromosomes of first meiotic metaphase (MI) spermatocytes in both species invariably formed bivalents synchronously with the autosomes and formed parachute-type bivalents, suggesting that the species in this genus share a common sex bivalent mechanism.