Megalostomis

Among the species of Megalostomis, the head and thorax are highly variable. The most useful morphological characters include the presence of a carina in the inter-ocular area, development of anterior teeth on the mandibles, clypeus sculpture, and the degree of retraction of the head inside the prothorax. Sexual dimorphism is pronounced, with greater development of mandibles, presence of constrictions on the pronotal disc, development of double infraocular projection, and lengthening of forelegs in males. The thorax may have strong constrictions, often present in species with great development of the head and mouthparts. The most distinctive characters for species recognition are the coloration pattern and the ordering of the elytral punctation. The abdomen and legs are not especially useful for species-group recognition. The genus is supported by two synapomorphies: eyes strongly emarginated and dorsal plate of aedeagus with straight margin.

Literature