Swedish Malaise Trap Project (SMTP) - Dolichopodidae

Study Extent

Malaise trap localities ranged from Sandhammaren and Hamburgsund on the south and southwest coasts, respectively, to the northern border of Sweden at Nuolja and Vasikavuoma. Within this area, 73 Malaise traps were placed at 54 sites were selected in the interest of sampling a diversity of habitats meeting criteria for logistical, maintenance concerns. The altitude range of the trap sites was from near sea level to 900 m.

Sampling

Most of the approximately 20 million specimens from SMTP samples were preserved in alcohol, shipped to and stored at Station Linné, Öland. The collecting events range from a few days to several weeks depending on the frequency at which the sampling containers needed to be replaced: shorter time periods characterize spring and summer sampling events, during which there was a higher abundance of most insects. Specimens identified to generate these sample-based datasets are distributed among public entomology collections as vouchers in taxonomic and phylogenetic studies, with primary types housed at the Swedish Museum of Natural History (NRM). Other terrestrial arthropods (e.g., spiders, mites, springtails) and invertebrates (e.g., snails, earthworms) recorded from SMTP samples are not included in this dataset.

Quality Control

The occurrence datasets returned to SMTP staff were validated and cleaned, with names used for identifications matched to those of the national species checklist (DynTaxa) and the European species checklist (Fauna Europaea).

Method steps

1. Raw trap samples were sorted by taxonomy into increasingly restrictive units, resulting in more than 300 taxonomic fractions (see http://www.stationlinne.se/en/research/the-swedish-malaise-trap-project-smtp/taxonomic-units-in-the-smtp/), which were sent to collaborating experts for identification. Over 100 taxonomic experts from around the world were involved in identifying this material, which represents 165,000 specimens. These datasets were reorganized into 79 datasets, each corresponding to a set of samples of a particular taxon or assemblage of taxa (“analysis taxon”) processed by a different expert or group of experts. The analysis taxa mostly correspond to families or subfamilies of Diptera and Hymenoptera, and orders or parts of orders for other insect groups. The data analyzed represent all the cleaned data files that were available in the spring of 2017. In total, there are 127 files, most of which contain abundance data (117 files) but some of which only provide incidence data (10 files). The analyzed information is estimated to represent from 2 to 67 % of the entire catch of each analysis taxon (Table S4). In total, the abundance data comprise 157,225 specimens (30,643 records) identified to 3,916 taxa. The incidence data represent another 1,516 observations and 279 taxa. The incidence data roughly corresponds to 7,800 specimens, if this material contained the same average number of specimens per species and sample as the material covered by the abundance data.

Separate datasets from the full suite of analyzed species occurrence records correspond to batches of identified samples defined as an “analysis taxon” (Ronquist et al., 2019). In most cases, this refers to a family or subfamily of either Diptera or Hymenoptera; otherwise, the “analysis taxon” represents several to all families in other insect orders. The identifications cover nearly 4,000 species, of which over 600 are new to science.

1. Animalia
   rank: kingdom
2. Arthropoda
   rank: phylum
3. Insecta
   rank: class
4. Diptera
   rank: order

The study area is within the political territory of Sweden, including the islands of Öland and Gotland.