Morpho-anatomy ofXerephedromiya ustjurtensis(Diptera: Cecidomyiidae) induced galls and intersexual variation of gall density inEphedra distachyaL. (Ephedraceae) from Ukraine

Abstract

We described the structure of two different morphological gall types, subglobular and fusiform in Ephedra distachya. The gall midge, Xerephedromyia ustjurtensis Fedotova (Diptera: Cecidomyiidae) induces both types of gall formation. Galls are persistent resinous stem swellings usually subglobular and rarely fusiform in shape. Mature galls are solid, hard, indehiscent woody structure with many circular exit holes on their surface. Galls are anatomically similar, but different from the unaffected stems. The mean number of larval cavities varied significantly between subglobular and fusiform galls, while variation of diameter of the larval cavities was not significant between the gall morphotypes. We documented significant (p < 0.05) variation in total gall densities between sexes of Ephedra distachya, where male plants (mean = 0.89 ± 0.15) supporting higher gall densities than females (mean = 0.36±0.04). Total gall densities varied significantly (p < 0.05) among three sample populations of E. distachya and exhibited an increasing trend from mesic to xeric sites along an altitudinal gradient. Gall size also varied between plant sexes and among sites.