Morphometric geometry study on wings of grasshoppers: reflect more evolutionary flexibility in hind wings.

Abstract

Evolutionary changes in wings of neopteran insects has been examined in different groups to large extent but less in grasshoppers . Wings of insects have been considered as favourite structures to analyse diversity among  the species. Morphometric Geometry studies, applied to analyse the wing structure in twenty species of grasshoppers indicated both forewings and hind wings have followed a similar pattern of vein organisation, specific to both of these wing pairs. The fore wings had all the vein complements emerging from their respective sclerite in the cubital lobe.The anal lobe of fore wings had reduced size and had two narrowly separated parallel running anal veins with restricted flexibility . This structural organization of the  fore wing helped in straight positioning of these wings over folded hind wings extended over the abdomen and these serve as important structures for camouflage. Our Observations revealed that the hind wings irrespective of the species had all the vein complements in the cubital lobe plus vein complements ranging between 3-10 in the  anojugal lobe. also indicated that radial veins of hind wings had more number of branches than other vein complements that has contributed towards the increase of wing nervures and cells in between. Wide angled placement of veins in both the lobes increased the laminar space of hind wings as well its curvature in all the twenty species. The cross vein links are more prominent in hind wings as squares but rectangular in fore wings. The critical statistical analysis revealed three way clustering of grasshoppers relatedness, majorly influenced by the number of anal veins and degree of divergence of different veins in both the pairs of wings. The wing venation pattern of grasshoppers bear evolutionary significance and   represents a typical orthoptera wing type.