Cyst deposition behaviour and the functional morphology of the brood pouch in Streptocephalus torvicornis (Branchiopoda: Anostraca)

Abstract

The cyst deposition behaviour of Streptocephalus torvicornis is described as the first documented case of active cyst deposition in Anostraca. The functional morphology of the brood pouch of S. torvicornis is described and illustrated using both Light Microscopy and Scanning Electron Microscopy. The brood pouch is an elongated tube-like structure with a subterminal crescent-shaped opening. During cyst deposition, the females insert this structure into the sediment to a depth of almost 10 mm, and deposit the resting cysts, analogous to an insect ovipositor. The opening mechanism of the genital pore is explained by contraction of a branched longitudinal muscle. The adaptive value of laying cysts into the soil and possible dispersal strategies are discussed.