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Freie Universität Berlin (2004)

Phylogeny and zoogeography of the Sericini in the Himalayan region

Ahrens, Dirk

Titre : Phylogeny and zoogeography of the Sericini in the Himalayan region

Phylogenie und Zoogeographie der Sericini des Himalaya-Gebietes

Auteur : Ahrens, Dirk

Université de soutenance : Freie Universität Berlin

Grade : Doctoral thesis 2004

Résumé partiel
1) To determine the phylogenetic position of the Sericini (Coleoptera : Scarabaeidae), cladistic analyses were performed. The taxa included in the analysis represent most the "traditional" subfamilies of coprophagous and phytophagous Scarabaeidae, with emphasis on the Sericini and melolonthine lineages. Several poorly studied exoskeletal features have been examined including the elytral base, posterior wing venation, mouth parts, endosternites, coxal articulation, and genitalia. The results of the analysis strongly support the monophyly of the "orphnine group" + "melolonthine group". This clade was identified as the sister group to the "aphodiine line" including Aphodius + Copris. The "melolonthine group" is comprised in the strict consensus tree by two major clades, with the included taxa of Euchirinae, Rutelinae, and Dynastinae nested together in one of the clades ("melolonthine group I"). Melolonthini, Cetoniinae, and Rutelinae are strongly supported as being monophyletic, while Melolonthinae and Pachydemini appear as paraphyletic. Sericini + Ablaberini were identified in the analysis to be sister taxa nested within the "melolonthine group II" clade. As this clade is distributed primarily in the southern continents, one could assume that Sericini + Ablaberini are derived from one of these southern lineages. It is plausible that the ancestors of Sericini + Ablaberini and Athlia were separated by a vicariance event, such as the separation of the African plate from the rest of Gondwana, while Sericini and Ablaberini likely diversified during early Tertiary, with dispersal of some basal Sericini to South America. 2) The Sericini constitute a monophyletic group based on the following apomorphies : (1) vestigial (9th) sternite in the spiculum gastrale absent ; (2) cranial process of the spiculum gastrale filiform, very slender and circular in cross section ; (3) glandulae accessoriae with left and right glandulae (1+2) having a common duct to the vagina ; (4) basal ostium of phallobase small ; and (5) metacoxa enlarged. 3) To explore the diversification patterns of Sericini in the Himalaya, eight monophyletic groups have been analysed using cladistics, including Anomalophylla, Calloserica, Lasioserica/ Amiserica, Maladera (subgenus Omaladera), Maladera (subgenus Cycloserica), Serica, Sericania, and Xenoserica gen. n./ Nipponoserica. The Himalayan region has been treated as unit embracing the complex system of nearly parallel mountain ranges, from North Burma in the east to nearly Afghanistan in the west (approximately between 72° and 91° E and 27° and 36°N). 4) All Himalayan sericine taxa belong to a distal sericine lineage ("modern" Sericini), sharing the following apomorphic characters states : the presence of a carina from the craniolateral margin of the mesosternum to the mesofurcal arm and the acutely bent anterior anal vein (AA). 5) The phylogenies found show a congruent pattern in groups with similar vertical and/or horizontal distribution. Patterns of vertical and/or horizontal distribution are shown to be of crucial importance for gene flow, dispersal capacity, and for the opportunity to occupy new habitats. In lower montane species, major distal clades are generally restricted to the Himalaya, as revealed in Omaladera or Lasioserica.

Mots clés : scarab beetles, Himalaya, cladistic analysis, morphology, biodiversity

Présentation et version intégrale

Page publiée le 30 décembre 2014, mise à jour le 2 novembre 2018