A COMPARATIVE STUDY OF THE HAEMOCYTES (BLOOD CELLS) OF COCKROACHES (INSECTA: DICTYOPTERA: BLATTARIA), WITH A VIEW OF THEIR SIGNIFICANCE IN TAXONOMY

Abstract

Haemocytes are described and illustrated for 16 species of cockroaches, and data are given on haemocyte size and numbers. Each family in the suborder Blattaria is represented. In all of the species, the haemocyte complex comprises plasmatocytes and granular haemocytes in addition to mainly germinal elements, the prohaemocytes. Spherule cells, a distinctive form of granular haemocyte, occur in most "modern" species (superfamily Blaberoidea), but are absent from most species in the more primitive group (superfamily Blattoidea). Taxonomic relationships at other levels are reflected particularly in morphological features of granular haemocytes. Although the haemocyte complex alone offers insufficient evidence for systematic arrangement, it provides additional characters for classifying species.