The Costa Rican Systenus Loew (Diptera: Dolichopodidae): rich local sympatry in an otherwise rare genus

We present a summary and analysis of the Diptera-related information published in Zootaxa from 2001 to 2020, with a focus on taxonomic papers. Altogether, 2,527 papers on Diptera were published, including 2,032 taxonomic papers and 1,931 papers containing new nomenclatural acts, equivalent to 22% of all publications with new nomenclatural acts for Diptera. The new nomenclatural acts include 7,431 new species, 277 new genera, 2,003 new synonymies, and 1,617 new combinations. A breakdown by family of new taxa and new replacement names proposed in the journal during the last two decades is provided, together with a comparison of Zootaxa’s output to that of all other taxonomic publications on Diptera. Our results show that the journal has contributed to 20% of all biodiversity discovery in this megadiverse insect order over the last 20 years, and to about 31% in the last decade.

Insects perform essential ecological processes, such as pollination, nutrient cycling, and biological control, which are important for ecosystem functioning (Schowalter 2011). However, these services are threatened due to the loss of insect species diversity caused by the destruction and fragmentation of native vegetation and the production of agricultural crops with high environmental impact, such as conventional monoculture systems with high pesticide and herbicide usage (Tilman et al. 1994; Hunter 2002; Fahrig 2003; Bettiol 2010). These environmental disturbances may lead to changes in the community structure, such as differential species abundance and dominance, and the higher probability of population outbreaks (Andow 1983, 1991; Altieri & Letourneau 1984; Ponti et al. 2007).

The Dolichopodidae (Diptera) of the Galápagos Islands (Ecuador) are reviewed. The fauna comprises 17 species, which are described, illustrated, and keyed. Further, relevant New World taxa are discussed, with information on diagnostic characters, species groupings and new synonyms. Nine species are newly described: Amblypsilopus depilis, Medetera galapagensis, Paraclius desenderi, Chrysotus baerti, Asyndetus wigginsi, A. maelfaiti, A. cavagnaroi, A. mystacinus, and A. bursericola. The following synonyms are newly established: Condylostylus longicornis (Fabricius) (=C. detitaticauda Van Duzee), Chrysotus brevicornis Van Duzee (= C. brevispina Van Duzee, = C. latifacies Van Duzee, = C. mexicanus Robinson), and Asyndetus tibialis (Thomson) (= A. ridiculus Parent). The ecology and origin of the Galápagos Dolichopodidae are discussed, and the fauna is regarded as an extension of the New World mainland coastal and littoral fauna. New distributional records from North and South America are included, and the systematic relationships of Galápagos species are discussed.

Diptera of the middle Eocene Kishenehn Formation. I. Documentation of diversity at the family level