The cytogenetics and cytotaxonomy of Chrysolina Mots. and Oreina Chevr. (Coleoptera, Chrysomelidae, Chrysomelinae)

Thirteen species of Chrysolina and four of Oreina have been chromosomally a nalyzed. C. (Euchrysolina) graminis and three species of Oreina, O. (s.str. ) basilea, O. (Chrysochloa) speciosissima and O. (Protorina) ludovicae have shown a diploid number of 24 chromosomes and a 11 + Xy(p) male meioformula . Oreina (s.str.) viridis has an asymmetrical karyotype of 9 + Xy(p) meiofo rmula, probably derived from the former 11 + Xy(p) by two centric fusions. The Chrysolina of subgenus Stichoptera are chromosomally heterogeneous but all of them share asymmetrical karyotypes a fact which probably supports th eir common ancestry, C. latecincta and C. ripoceanensis have 11 + Xy(p), C. gypsophilae 15 + Xy(p), and C. sanguinolenta 16 + Xy(p). C. (Hypericia) hy perici and C. (Hypericia) quadrigemina display 38 chromosomes in agreement with another species of that subgenus. The recent proposal of joining C. fu liginosa and C. lepida within the subgenus Allochrysolina is reinforced by their common diploid number of 42 and 20 + Xy, meioformula. C. (Heliostola) ,montana shares the same 19 + Xy(p) meioformula with the species of the som ewhat related subgenus Chalcoidea which also lives on Asteraceae. C. (Crasp eda) limbata shows a 20 + Xy(p) meiformula, quite similar to the 19 + Xy(p) previously found in species of the subgenera Colaphodes and Ovosoma which also feed on Plantaginaceae C. (Threnosoma) helopioides presents the highes t chromosome number, 2n = 47 and 23 + X male meioformula, in agreement with that found in another species of Threnosoma. The proposed chromosomal evol ution of Chrysolina, mainly due to centric fissions and coupled to their ho st-plant shifts, is not contradicted by the molecular phylogeny even though the latter provides a better resolution. The possible joining of Chrysolin a and Oreina within a same genus might be supported by the cytogenetic data but should await enlarged analyses of molecular phylogenies.