| Abstrakt: |
Abstract: Large prosomal scent glands are characteristic of all Opiliones. These glands are most conspicuously developed in the suborders Laniatores and Cyphophthalmi, but less so in the third classical opilionid suborder, the Palpatores. In the present study, the glands of several soil-dwelling opilionids were investigated by scanning electron microscopy and semithin-histological sectioning. Several different glandular types were detected: the Trogulus-type, as found in Trogulus tricarinatus (Linnaeus, 1767), is characterized by an external secretion-atrium covering the ozopores and the presence of solid balls of secretion in the scent gland reservoirs. The lumina of scent glands in Anelasmocephalus hadzii Martens, 1978 are filled with cobweb-like projections of the glandular epithelium. These glands also open into a secretion atrium. The scent glands of Paranemastoma quadripunctatum (Perty, 1833) exhibit some characteristic features of defensive glands, e.g. large reservoirs the intima of which are extensively folded. Ozopores, however, still lead into a laterally-opening secretion atrium. Amilenus aurantiacus (Simon, 1881), the only eupnoid species in this study, has scent glands with large secretory cells but comparably small glandular reservoirs. Unlike the hidden ozopores of all three soil-dwelling opilionids of the suborder Dyspnoi investigated in this study, the slit-shaped scent gland openings of Amilenus aurantiacus are exposed on a cuticular protrusion dorsal to legs I. The presence of distinct types of scent glands, especially in soil- (and cave-) dwelling Palpatores, may be indicative of multiple evolutionary traits that possibly resulted in their functioning as both scent and defence glands. |
