We have analyzed the chromosomes of two species of East Asian fishfties. Neochauliodes nigris and Neochauliodes jorlllosalllls. The ch romosome number in both species is 2n =2 0 consisting of 9 pairs of autosomes plus the XX chromosomes in females and the Xy (forming Xyp bivalent in the first meiotic metaphase) in males. The each X chromosome is metacentric or sub metacentri c while the y is the smallest chromosome of the set. The sex chromosomes of first meiotic metaphase (MI) spermatocytes in

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... both species invariably formed bivalents synchronously with the au tosomes and formed parachute-type bivalents sim ilar to chromosomes of the genu s Parachauliodeds. Karyotypes of these two species of fish flies. N. Iligris and N. jorlllosalllls. are indistinguishable. The Xyp system which has been common ly known among Coleopterans seems to be also common among Corydalidae.