Species richness estimations of the megadiverse scuttle fly genus Megaselia (Diptera: Phoridae) in a wildfire-affected hemiboreal forest

Abstract

The species richness of the scuttle fly (Diptera: Phoridae) genus Megaselia was estimated by various non-parametric estimators from EstimateS, Species Prediction And Diversity Estimation (SPADE) and Ws2m, based on material from a Swedish hemiboreal forest area recently affected by major wildfires, Tyresta National Park and Nature Reserve (TNPNR), south of Stockholm. A total of 21 249 individuals were collected in Malaise traps, of which males constituted 16 976 and females 4 273. The analysed dataset represents 37 samples containing 18 549 specimens sorted into 330 species (184 described, 146 are either undescribed or of unsettled taxonomic status). It was not possible to estimate the total species richness using all samples due to heterogeneity caused by inclusion of different communities and temporal incoherencies between samples within and between years. Even with material obtained from a sampling program that was not designed for species richness estimates, it was possible to obtain reliable results when sample heterogeneity was minimized. By dividing the data into community-specific datasets - for bog, forest and wildfire - it was possible to obtain asymptotic curves for the smaller of the two wildfire datasets. A total estimate of 357-439 (95% CI) was attained by using the smaller wildfire dataset and adding the 85 unique species from the samples not included in the estimation analysis. TNPNR has one of the richest known scuttle fly communities in Europe, consisting of almost 50% of the currently named Megaselia species; 48 of these species are reported as new records for Sweden in this study.