Effects of miniaturization in primary larvae of Strepsiptera (Insecta).

In this review the presently available morphological data on primary larvae of Strepsiptera are interpreted with respect to effects of miniaturization, but also their possible functional or phylogenetic background. The morphology of the 1st instars is mainly affected by functional constraints linked with parasitism but also by very distinct effects of miniaturization. The latter include modifications of the cephalic cuticle, the extremely limited free space in the body lumen, the shift of origins of cephalic muscles to the thorax, a reduced number of cephalic and thoracic muscles, extensions of muscles with cell bodies and other organelles, and an extreme concentration of the entire central nervous system in the middle region of the body. Pad-like adhesive structures on the distal leg segment and the abdominal jumping apparatus are clearly linked with the necessity to attach to a potential host but would not function in distinctly larger organisms.