Diptera: Dolichopodidae)

662 Phylogenetic analyses using molecular markers reveal ecological lineages in Medetera (Diptera: Dolichopodidae) Marc Pollet, Christoph Germann, Marco Valerio Bernasconi Abstract*Medetera Fischer von Waldheim is the most speciose genus in the Medeterinae, with a nearly ubiquitous global distribution. Phylogenetic relationships within Medetera and between Medetera and four other medeterine genera were investigated using mitochondrial (COI, 16S) and nuclear (18S) markers to test morphological hypotheses. Our results confirm most of Bickel’s hypotheses. Thrypticus Gersta¨cker shows a sister-group relationship with Medetera Dolichophorus Lichtwardt. The Medetera species included here split into two clades. One clade corresponds to the M. diadema L. Á veles Loew species group sensu Bickel. The second clade is largely composed of the M. apicalis (Zetterstedt) species group sensu Bickel and the M. aberrans Wheeler species group sensu Bickel Dolichophorus. Although most Medeterinae are associated with plants (mainly trees), species in at least two separate lineages demonstrate a secondary return to terrestrial habitats. The implication of this evolutionary phenomenon is briefly discussed. Re´sume´*Medetera Fischer von Waldheim est le genre des Medeterinae le plus riche en espe`ces, et est pratiquement ubiquiste dans sa distribution globale. Les relations phylo- geńe´tiques a` l’inte´rieur de Medetera et entre Medetera et quatre autres genres de Medeterinae ont e´teé´tudieés a` l’aide de marqueurs mitochondriaux (COI, 16S) et nucleáire (18S) pour tester les hypothe`ses morphologiques. Nos re´sultats confirment la plupart des hypothe`ses de Bickel. Thrypticus Gersta¨cker montre une relation de groupe-sœur avec Medetera Dolichophorus Lichtwardt. Les espe`ces de Medetera incluses se se´parent en deux clades, dont l’un correspond au groupe d’espe`ces de M. diadema L. Á veles Loew (sensu Bickel). Le second clade est compose´ en grande partie du groupe d’espe`ces de M. apicalis (Zetterstedt) (sensu Bickel), et du groupe d’espe`ces de M. aberrans Wheeler (sensu Bickel) Dolichophorus Wheeler. Bien que la plupart des Medeterinae soient associe´s a` des plantes (principalement des arbres), dans au moins deux ligneés se´pareés des espe`ces montrent un retour secondaire a` des habitats terrestres. L’implication de ce pheńome`ne e´volutionnaire est brie`vement discute´. Introduction listed 17 genera, of which Saccopheronta With over 7100 known species, the Dolicho- (Becker) is considered a synonym of Medetera podidae represent one of the most speciose Fischer von Waldheim (see Pollet et al. 2004). dipteran families in the world (Pape et al. 2009). Euxiphocerus Parent, on the other hand, was Within this family, Medeterinae account for first treated as a member of the Rhaphiinae, but about 8% of the species diversity. A total of 22 is currently considered closely related to genera are currently assigned to this subfamily. Systenus Loew, which renders it medeterine Yang et al. (2006; see also Sinclair et al. 2008) (Grichanov 2010). In addition, the following Received 19 December 2010. Accepted 1 March 2011. M. Pollet, Research Group Terrestrial Ecology, Department of Biology, Ghent University, K.L. Ledeganckstraat 35, B-9000 Ghent, Belgium, and Department of Entomology, Royal Belgian Institute of Natural Sciences, Vautierstraat 29, B-1000 Brussels, Belgium C. Germann, M.V. Bernasconi,1 Zoological Museum, Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland 1Corresponding author (e-mail: [email protected]). doi: 10.4039/n11-031 Can. Entomol. 143: 662Á673 (2011) # 2011 Entomological Society of Canada Downloaded from https:/www.cambridge.org/core. University of Basel Library, on 30 May 2017 at 15:44:41, subject to the Cambridge Core terms of use, available at https:/www.cambridge.org/core/terms. https://doi.org/10.4039/n11-031 Pollet et al. 663 five medeterine genera have been described tic status of species and genera. Attempts to since 2006: Papallacta Bickel, Pharcoura Bickel, split off species into new genera (often on the Neomedetera Zhu, Yang and Grootaert, basis of a single character, e.g., two scutellar Systenomorphus Grichanov, and Systeno- bristles instead of four in Oligochaetus Mik) neurus Grichanov. Some of the genera, like have ultimately proved to be invalid. Also, the Palaearctic Cyrturella Collin and some reverse cases in which species were the Neotropical Microchrysotus Robinson, synonymized on the basis of variability in Microcyrtura Robinson, and Micromedetera the shape of hypopygial appendages remain highly questionable (Grichanov 2002). For Robinson, are minute (1 mm long or less) these reasons and as a first attempt to test and are usually termed micro-dolichopodids some of the morphological hypotheses pro- (Robinson 1975; Bickel 2009; Runyon and posed by Bickel (1985, 1986), Negrobov Robinson 2010). Their systematic position and von Stackelberg (1971, 1972, 1974a, remains largely uncertain. Also, the recently 1974b), Negrobov (1977), and Grichanov described Nearctic micro-dolichopodid genus (2002), molecular markers were used to in- Hurleyella Runyon and Robinson may belong vestigate the phylogenetic structure within to the Medeterinae but is currently considered Medetera and between Medetera and four incertae sedis (Runyon and Robinson 2010). other medeterine genera. Only three genera (Medetera, Systenus, and Thrypticus Gersta¨cker) show a worldwide distribution (Yang et al. 2006; Grichanov and Materials and methods Mostovski 2009), Medetera being by far the most speciose in this subfamily, with nearly Samples 60% of the species. Over 160 Medetera species, A total of 37 specimens of 30 dolichopodid or nearly one-half of the currently known species were included in the present study, global diversity, are described from the with 29 species (36 specimens) of Medeterinae Palaearctic Region, mainly as a result of the as ingroup and Neurigona quadrifasciata remarkable efforts of Negrobov (Negrobov and F. (Neurigoninae) as outgroup. The two sub- von Stackelberg 1971, 1972, 1974a, 1974b; families share a number of characters, such as Negrobov 1977). However, Negrobov did not the convex postcranium (occiput), the flattened prescutellar depression, the lack (or consider intraspecific and (or) geographical rather secondary loss) of preapical bristles variability, unlike Bickel (1985, see the treat- on the hind femur, the large pedunculate ment of M. apicalis (Zetterstedt)) and it is hypopygium (Bickel 1985), and an arboreal probable that Palaearctic Medetera are over- life history. For these reasons the subfamily split and include a number of rather variable Neurigoninae has been used as outgroup in species. Medetera is usually found on tree the past as well (Bickel 1985, 1987). Moreover, trunks and other vertical substrates, and larvae a likelihood analysis conducted by Lim et al. of some species are known as predators of bark (2010) revealed a sister-clade phylogenetic beetles (Coleoptera: Curculionidae: Scolyti- relationship between the Medeterinae and nae) (e.g., Fitzgerald and Nagel 1972; Nagel Neurigoninae, though without statistical sup- and Fitzgerald 1975). port. Twenty-four Medetera species made up In Medetera, unlike many other dolichopo- part of the present taxon sample, with 20 did genera, conspicuous male secondary sex- Palaearctic, 2 Neotropical, and 2 Oriental ual characters are rare, with the flattened species (the last species were also used in tarsomeres of the fore leg in the M. aberrans Lim et al. 2010), next to Palaearctic Dolichophorus Wheeler species group as the most obvious Lichtwardt, Thrypticus, Systenus, and Oriental exception (Bickel 1985). The lack of these Paramedetera Grootaert and Meuffels. Taxon diagnostic features and the use of characters sampling was largely based on the availability of ambiguous polarity have often led to of fresh specimens, suitable for sequencing. uncertainty and confusion about the systema- Only 4 of the 15 Medetera species groups # 2011 Entomological Society of Canada Downloaded from https:/www.cambridge.org/core. University of Basel Library, on 30 May 2017 at 15:44:41, subject to the Cambridge Core terms of use, available at https:/www.cambridge.org/core/terms. https://doi.org/10.4039/n11-031 664 Can. Entomol. Vol. 143, 2011 sensu Bickel (1985, 1987) are represented here, proved to be sufficiently satisfactory with the but the data set holds species previously default parameters and did not require parti- placed in Oligochaetus and Saccopheronta, cular manual interventions. and species synonymized by Grichanov Phylogenetic reconstruction was carried out (2002). Information on the samples investi- using Bayesian analysis (BAY), performed gated here is given in Table 1. All samples were with MrBayes version 3.1.2 (Ronquist and conserved in 100% ethanol at 20 8C. Huelsenbeck 2003), and with the maximum- likelihood (ML) method using the RAxML Web-Servers version 7.0.4 (Stamatakis et al. DNA extraction, amplification, and sequencing 2008). Modeltest 3.5 (Posada and Crandall DNA was extracted using a DNeasy Tissue 1998) enabled us to identify the evolutionary kit (Qiagen AG, Hombrechtikon, Switzerland) model(s) fitting the data better for both the following the manufacturer’s instructions (for BAY and the ML analyses. For this purpose, more details see Bernasconi et al. 2007a, data were partitioned by gene (COI, 16S, and 2007b). Standard PCR reactions and subse- 18S)

Load more