New record of B-chromosome through meiosis in the Egyptian locust Anacridium aegyptium (Acrididae) with indication to its origin

The basic chromosome complement of the Egyptian male locust, Anacridium aegyptium; collected from Giza Governorate, Egypt, is 2N = 22 + XO. All autosomes and sex chromosome are telocentric. The autosomes can be divided into three size-groups; three long (L1–L3), five medium (M4–M8) and three short chromosomes (S9–S11). The X-member is the longest member of all chromosomes. An extra telocentric B-chromosome was detected in two males of the collected locusts, nearly equal in size with S10-member and thus the chromosome complement of these males is 2N = 22 + XO + B. The origin of this extra member is discussed through its behaviour through meiosis that studied. The B-chromosome was frequently observed neighbouring the X-chromosome through most of the meiotic stages and this behaviour reinforces the present suggested hypothesis that B-chromosome was originated from X-chromosome.