A SCANNING ELECTRON MICROSCOPE STUDY OF SPINNING APPARATUS IN TWO SPECIES OF SPIDERS FROM GHARBIA PROVINCE (EGYPT)

The silk spinning apparatus in the spiders, Filistata insidiatrix and Holocnemus pluchei was studied with scanning electron microscopy and the main microstructural characteristics of the silk spinning tubes were described. Each of the two species possesses three pairs of spinnerets, the anterior, middle and posterior ones. The spinnerets have only three types of silk glands, which connected through the typical spinning tubes (spigots) on the spinnerets. These spigots are the ampullate, pyriform and tubuliform tubes. The arrangement, mode of distribution and the microstructure of the spigots were recorded. The distinct difference between the two studied species was the presence of a cribellum located between the anterior spinnerets in the F. insidiatrix, while the other species “H. pluchei” was devoid of this structure. The probable functions of the spigots and cribellum were discussed.