G. it. Ent., 5 (28): 309-323
August 31, 1991
Estudio biogeográfico-ecológico preliminar del género
Plusiotis Burmeister
(Coleoptera: Melolonthidae, Rutelinae)
por
MIGUEL-ANGEL MORÓN
Abstract - A preliminary biogeographical-ecological study on the genus Plusiotis Burmeister (Coleoptera: Melolonthidae, Rutelinae) - In order to confirm their inclusion in the Meso-American Montane Distribution Pattern proposed by Halffter (1978), the habits and geographical-ecological distributions of 66 species of Plusiotis are analyzed. An evolutionary sequence is proposed in order to explain the origin of the sapro-xylophagous habits of the American Rutelini larvae; the known hosts for the larvae in 19 genera of this tribe, including Plusiotis, are listed. This study makes emphasis on the present distribution of the species of the "lecontei, adelaida, laniventris, prasina, costata, auripes, victorina and lacordairei groups", the apparent origin of which has to be inquired into a dispersal process from the Central American Nucleous to the south-western United States. A map containing the proposed dispersal routes is given for each group. It is corroborated that the species of Plusiotis are predominantly montane and hygrophilous, reaching their greatest diversity and abundance between 1000 and 2000 m of altitude. Owing to their present distribution and the higher number of simplesiomorphies exhibited, the species of the "lecontei, adelaida and laniventris groups" are proposed representing the most ancient lineages, which could colonize the mountains to the north of the Isthmus of Tehuantepec during Pliocene. Likewise, the reasons supporting the hypothesis of a second dispersal process during Pleistocene are exposed. Detailed comments on the possible influence of vulcanism on the diversification, isolation and dispersal of these groups of species are added, emphasising the importance of the Mexican Neovolcanic Axis as a corridor-filter to the Plusiotis groups dispersal towards the north-west.
