Morphologische Indizien für das unmittelbare Schwestergruppenverhältnis der Schizophora mit den Syrphoidea (‘Aschiza’) in der phylogenetischen Systematik der Cyclorrhapha (Diptera: Brachycera)

Abstract

The phylogenetic relationships of the Schizophora with the families of the Aschiza were investigated on the basis of synapomorphies. Depending on the family, the sensory epithelium of the retinae of the compound eyes of flies consists either of populations of two ommatidial elements or of uniform ommatidia: duotype and monotype respectively. Within the Cyclorrhapha, the monotype occurs exclusively in the Schizophora and Syrphoidea (= Syrphidae + Pipunculidae), whereas the duotype occurs in the remaining Aschiza. These two types form a plesio-apomorphous pair: on the basis of character state analysis the duotype was regarded as plesiomorphous and the monotype proved to be a synapomorphy of the Schizophora and Syrphoidea. The retinal pair was accorded a high relevance as an indicator of the phylogenetic relationships in Cyclorrhapha owing to its special morphology and the very low probability of a parallel development of the apomorphous monotype.

In this paper the hypothesis (Hennig, 1976) that the dorsobasal arista on the antennal flagellum in the Schizophora and Syrphoidea is a synapomorphy compared to the original apical arista was confirmed on the basis of literature studies.

The monophyly of these two groups together, and their sister group relationship, were demonstrated in an argumentation scheme. Three alterations of the conventional systematics of the Cyclorrhapha were undertaken: (a) the term ‘Eumuscomorpha’ was introduced to designate a new monophyletic taxon of the Schizophora and Syrphoidea. (b) The remaining groups of the Aschiza were temporarily subsumed in a ‘superfamily Platypezoidea’ owing to their manifestation of complementary symplesiomorphous characteristics. Until its phylogenetic character (monophyly or paraphyly) is unequivocally clarified, it remains an ‘artifical’ entity. (c) The term ‘Aschiza’ is for a taxon of the genealogical system no longer applicable.

Keywords :

• Schizophora
• Syrphoidea
• phylogenetic relationship
• synapomorphy
• retinae of the compound eyes
• dorsobasal arista