Histochemical characterization of secretions in the reproductive systems of two species of branchiobdellidans (Annelida: Clitellata): a new character for the phylogenetic matrix?

Abstract

The species description of Cambarincola holti was emended to include variations in appearance of the peristomium, a description of the jaws, the shape of a normal spermatheca, and the correct description of the glandular atrium, granular rather than vacuolar. The glandular atrium contained a single type of secretion granule characterized as mucoprotein or glycoprotein, with an alkaline protein component. The vacuolar prostate gland secretions are uncharacterized as no stains would attach to the material. Spermatozoa were sometimes found in the spermathecal duct, but usually they were clumped together in the spermathecal bulb, or randomly distributed with each acrosome being in contact with a lining cell. The digitiform, glandular atrium of Xironogiton victoriensis is composed of nine regions based on the staining reaction of the granules. The granules were characterized as neutral mucoprotein, nonsulfated acid mucosubstance, glycoproteins, a combination of sulfated and nonsulfated acid mucosubstances, and totally non-staining granules. Spermatophores were observed only in X. victoriensis in depressions on the clitellum. The spermatozoa were separated from the cuticle by a layer of PAS staining material and covered by a lighter, PAS staining cap with a foamy outer layer that stains lightly with AB2.5. Further studies to characterize the secretions of the male reproductive organs may produce an additional character to add to the data matrices for phylogenetic analyses of these clitellates.