A new and anomalous type of meiosis in a mantid, Callimantis antillarum saussure

Abstract

The general course of meiosis in the Orthoptera is remarkably constant from species to species, and even from one suborder to another. This is at any rate true of meiosis in the male sex; owing to technical difficulties, oogenesis has been studied in only a few species, but there seems no reason to believe that it is less uniform than spermatogenesis. Such deviations from normality as do occur seem to be of two main kinds. In some species the middle part of the prophase of the first meiotic division (pachytene, and sometimes diplotene as well) are replaced by a “diffuse stage” during which the chromosomes become almost impossible to fix and stain. Such a stage is apparently present in the peculiar orthopteran Schizodactylus monstrosus (McClung and Asana 1933, 1935)-In other species the chiasmata which usually occur more or less at random along the length of the meiotic chromosomes are localized in certain definite regions. Localization of chiasmata is seen in it's most extreme form in species of the genus Mecostethus (Acrididae), where only one chiasma is usually formed in each bivalent, just near the spindle attachment (White 1936).