TARSAL PAD LENGTHS ARE RELATED TO SURFACE-AREA-TO-VOLUME RATIOS IN CENTROBOLUS COOK, 1897

Abstract

Red millipedes (Centrobolus) have elongated tarsal pads. I tested for a relationship between tarsal pad length and surface-area-to-volume ratio and surface area in red millipedes Centrobolus. Specimens were fixed, first in 2.5% glutaraldehyde (pH 7.4 phosphate-buffered saline) at 4 °C for 24 hours, then in osmium tetroxide (2%). Dehydration through a graded alcohol series (50%, 60%, 70%, 80%, 90% to 100% ethanol) and critical point drying followed. Specimens were mounted on stubs and sputter coated with gold palladium. Tarsal pads and gonopods were viewed under a Cambridge S200 SEM. SEM micrographs were examined and the individual components of the gonopods were identified according to the species descriptions. One set of measurements was made from the micrographs (1) tarsal pad length and these were tested for a correlation with data for surface areas and surface-area-to-volume ratios. Tarsal pad length was negatively related to surface-area-to-volume ratios across two species (r=-0.99, Z score=-4.53, n=6, p<0.01). Tarsal pad length was not related to surface area (r=0.20, Z score=0.36, n=6, p=0.36).