Taxonomic revision and preliminary phylogenetic analysis of the subgenus Megalostomis (Scaphigenia) Lacordaire (Coleoptera: Chrysomelidae)

AGRAIN, FEDERICO ALEJANDRO; ROIG-JUÑENT, S. A.; DOMINGUEZ, M. C.

Insect Systematic and Evolution

Año: 2007 vol. 38 p. 335 - 359

1399-560x

The subgenus M. (Scaphigenia) Lacordaire includes six species distributed in arid regions ofSouth America. A systematic revision of this subgenus is presented, including re-descriptionsand an update of distribution data of the six species. A preliminary cladistic analysis is per-formed to test the relationships among the species of the subgenus and if the morphologicalcharacters used are suitable. A key is presented to separate the seven subgenera of Megalo-stomis Chevrolat as well as a key for the species of the subgenus M. (Scaphigenia). Maleaedeagus internal sac of the nine studied taxa are described and illustrated. This constitutes thefirst internal sac descriptions for members of this subtribe and could help clarify the homolo-gy of such structures within Cryptocephalinae. M. (S) consimilis Achard is reassigned to thespecies status on the base of genitalic characters. The cladistic analysis was done using forty-one characters from adult external morphology and male and female genitalia. Two species oftwo different subgenera of  Megalostomis: M. (Megalostomis), and  M. (Heterostomis)Lacordaire, and one representative of the genus Themesia Lacordaire were selected as outgroups. Results were obtained by implicit enumeration using parsimony software. Threeequally parsimonious trees were obtained of 45 steps, Ri=0.952, and Ci= 0.941. Support ofeach group was evaluated by Jacknifing, Bootstrap and Bremer values. Relationships betweenspecies are discussed.