Andricus quercuslaurinus Melika & Pujade-Villar, new species

Gall (Figs 37-38). Juicy integral monolocular leaf galls are located on the central vein, rarely on leaf petiole, causing a vein swelling. The fully grown gall is 13 mm long and 5.6 mm wide. Generally one gall per leaf occurs, rarely more; up to six galls per leaf were detected. In this case the separate galls are fused and it seems that the galls are multilocular. During the gall development, the colour of the surrounding leaf tissues changes from green to brown-yellow and the vein swelling is enlarging. As the cynipid larva matures, the main vein changes to purple colour. The central larval chamber is oval. When the gall matures, the tissues become hard. Adults emerge from early May to early July.

Biology. Alternate asexual and sexual generations are known, both inducing galls on Quercus laurina (Section Lobatae of Quercus, red oaks), which is distributed in Mexico, Guatemala and El Salvador (Govaerts & Frodin 1998). In the state of Hidalgo of Central Mexico, severe outbreaks of this newly described cynipid species cause the death of thousands of trees in natural stands of Q. laurina. The decline and death of trees is due to the twig and stem swellings caused by asexual galls. For Mexico, this is the first reported cynipid gallwasp capable to kill trees of different ages and sizes. A local infestation took place in a private forest in 2003 and the severe outbreak remained active until summer of 2009 without any signals of reduction of harmful impact, in spite of intensive management applied. There is no doubt that this species could expand its distribution and jeopardize the survival of Q. laurina in other parts of Mexico.

Distribution. Currently known from the type locality only: México, Estado de Hidalgo