Taxonomy and phylogeny of the Central European bug genus "Psallus" (Hemiptera, Miridae) and faunistics of the terrestrial Heteroptera of Basel and surroundings (Hemiptera)

Abstract

True bugs or Heteroptera are a biologically diverse, species-rich group containing some 37,000 species described worldwide (Schaefer & Panizzi, 2000). It is the largest taxon of endopterygotan insects and constitutes a well-supported monophylum within the order Hemiptera. Species are usually trophically specialised; they are phytophagous, zoophagous or mycophagous (Schuh & Slater, 1995). For their often specialised feeding habits, many species are economically important as crop pests, biological control agents of phytophagous insect pests (Schaefer & Panizzi, 2000) or as vectors of human diseases (Schofield & Dolling, 1993; Schaefer, 2000; Garcia et al., 2000). The last one is, however, without significance in Central Europe. Some bugs constitute an important protein source in human diet (Fritsche Gitsaga, 2000). Within the Heteroptera the plant bugs or Miridae constitute the largest family with more than 10,000 described species (Schuh, 1995). It is expected that the family may contain twice as many species (Wheeler, 2001). Even though the mirids contain many economically important species, its taxonomy and systematics contains many unsolved problems. This is a result of the large number of included taxa and the uniformity of external morphology of many genera. Current problems exist at species level where some taxa are ill-defined or where many species can be identified only by male genitalic characters, and at genus level where phylogenetic considerations are missing for many taxa. The first list of Swiss Heteroptera containing 50 species is part of Fuessly’s (1775) catalogue of insects from Switzerland. Several additional records were inlcuded in general works of 18th and 19th century entomologists (Sulzer, 1771, 1776; Razoumowsky, 1789; Roemer, 1789; Schellenberg, 1800; Meyer-Dur, 1843). The only catalogue dealing with Swiss bugs was provided by Frey-Gessner (1864a, b, 1865, 1866a, b, 1871a). Basel and the surrounding region have, compared to the rest of Switzerland, a distinct fauna and flora due to the geografical position and the relatively dry climate. The region is open to the Rhone valley via the Burgunderpforte from where mediterranean floristic and faunistic elements may immigrate. The first part of the present thesis deals with the ill-defined mirid genus Psallus (Phylinae, Phylini). One aim was to test the monophyly of Psallus and to propose, based on the study of the Central European species, a classification applicable to the world fauna. The second goal was to investigate the female genitalia in view of taxonomic and phylogenetic significance. Female genitalia are so far rarely used for species definition within mirids (exeptions e. g. Calocoris, Rosenzweig, 1997) in contrast to other families (e. g. Nabidae, Pericart, 1987). As for Psallus the few species of which the female genitalia have been described so far (Kullenberg, 1947; Seidenstucker, 1972; Matocq, 1989, 1997) suggest this may be an useful set of characters. A third aim of the present study was to provide keys for the identification of the Central European species based exclusively on male and female genitalic characters. The second part of the present study deals with the terrestrial bug fauna of the region of Basel. Currently most of our knowledge goes back to Frey-Gessner's catalogue (1864a, b, 1865, 1866a, b, 1871) – obsolete for a long time. A few scattered papers have been published since (e. g. Voellmy & Egli, 1981; Meduna et al., 2001) but a thorough inventory lacks to date. In Switzerland, in general, faunistic surveys on true bugs are scarce in contrast to other European countries. The relatively few papers recently published on Swiss Heteroptera are based, to a large extent, on material from traps run for ecological investigations (e. g. Otto, 1996; Di Giulio et al., 2000). The combination of systematic revisions and faunistic investigations is necessary if we want to know and conserve our fauna. Turnball (1979) brought this to the point: “How can we detect change in the future if we cannot define the fauna we now have?”