Remarkable fly (Diptera) diversity in a patch of Costa Rican cloud forest: Why inventory is a vital science

Abstract

Study of all flies (Diptera) collected for one year from a four-hectare (150 x 266 meter) patch of cloud forest at 1,600 meters above sea level at Zurquí de Moravia, San José Province, Costa Rica (hereafter referred to as Zurquí), revealed an astounding 4,332 species. This amounts to more than half the number of named species of flies for all of Central America. Specimens were collected with two Malaise traps running continuously and with a wide array of supplementary collecting methods for three days of each month. All morphospecies from all 73 families recorded were fully curated by technicians before submission to an international team of 59 taxonomic experts for identification.Overall, a Malaise trap on the forest edge captured 1,988 species or 51% of all collected dipteran taxa (other than of Phoridae, subsampled only from this and one other Malaise trap). A Malaise trap in the forest sampled 906 species. Of other sampling methods, the combination of four other Malaise traps and an intercept trap, aerial/hand collecting, 10 emergence traps, and four CDC light traps added the greatest number of species to our inventory. This complement of sampling methods was an effective combination for retrieving substantial numbers of species of Diptera. Comparison of select sampling methods (considering 3,487 species of non-phorid Diptera) provided further details regarding how many species were sampled by various methods.Comparison of species numbers from each of two permanent Malaise traps from Zurquí with those of single Malaise traps at each of Tapantí and Las Alturas, 40 and 180 km distant from Zurquí respectively, suggested significant species turnover. Comparison of the greater number of species collected in all traps from Zurquí did not markedly change the degree of similarity between the three sites, although the actual number of species shared did increase.Comparisons of the total number of named and unnamed species of Diptera from four hectares at Zurquí is equivalent to 51% of all flies named from Central America, greater than all the named fly fauna of Colombia, equivalent to 14% of named Neotropical species and equal to about 2.7% of all named Diptera worldwide. Clearly the number of species of Diptera in tropical regions has been severely underestimated and the actual number may surpass the number of species of Coleoptera.Various published extrapolations from limited data to estimate total numbers of species of larger taxonomic categories (e.g., Hexapoda, Arthropoda, Eukaryota, etc.) are highly questionable, and certainly will remain uncertain until we have more exhaustive surveys of all and diverse taxa (like Diptera) from multiple tropical sites.Morphological characterization of species in inventories provides identifications placed in the context of taxonomy, phylogeny, form, and ecology. DNA barcoding species is a valuable tool to estimate species numbers but used alone fails to provide a broader context for the species identified.

A DNA barcode library for 5,200 German flies and midges (Insecta: Diptera) and its implications for metabarcoding‐based biomonitoring

“…Further studies point to an enormous under-estimation of the species diversity in the Cecidomyiidae (Borkent et al, 2018;. Although our data do not allow for an accurate projection for the size of the total species numbers, it seems quite likely that this single family contains thousands of unrecorded species in Germany.…”

“…High proportions of unrecorded species were evident for the Agromyzidae, Anthomyiidae, Cecidomyiidae, Ceratopogonidae, Chironomidae, Chloropidae, Phoridae, Sciaridae and Sphaeroceridae, and to a lesser extent for the Empidoidea, Limoniidae, Mycetophilidae and others. Further studies point to an enormous under‐estimation of the species diversity in the Cecidomyiidae (Borkent et al, ; Hebert et al, ). Although our data do not allow for an accurate projection for the size of the total species numbers, it seems quite likely that this single family contains thousands of unrecorded species in Germany.…”

“…Taxonomists working on Diptera have long been well aware of the immense number of undescribed species (Bickel et al, ) with estimates of global Diptera species diversity ranging from 400,000 to 800,000 species compared with ~160,000 named species (Borkent et al, ; Pape, Blagoderov, & Mostovski, ). Hebert et al (), applying DNA barcoding to Canadian insects, proposed that the actual number of species could be much higher, suggesting the possible presence of 1.8 million species in just one family, the Cecidomyiidae (gall midges) alone.…”

The quest for the identity of Orthoceratium lacustre (Scopoli, 1763) reveals centuries of misidentifications (Diptera, Dolichopodidae)

“…This type of tedious time-consuming work is sometimes considered unnecessary or unwanted by peers for the simple reason that it might prevent researchers tackling the current and ever growing taxonomic impediment (Wheeler et al 2004; Borkent et al 2017), and this statement certainly contains some truth. However, it should not be forgotten how much (precious) time is invested not only to correct taxonomic mistakes from the past (e.g., current paper, Kazerani et al 2017), but also to verify the identity of species on the basis of insufficiently detailed descriptions without type material at hand.…”

First Tropical American Species of the “Relict” GenusLitoleptis,and Relationships in Spaniinae (Diptera: Rhagionidae)

“…Prior to the work of Kato (2016a, 2016b) on the Japanese species, the three described species as well as several undescribed ones have been known entirely on the basis of one or two specimens for each. Incredibly, Litoleptis tico escaped detection by over 20 entomologists, myself included, who intensively surveyed the patch of cloud forest that is its type locality in Zurqui de Moravia, Costa Rica (Borkent et al, 2018;Brown et al, 2018). That survey, called ZADBI (Zurqui All-Diptera Biodiversity Inventory), recovered hundreds of thousands of fly specimens collected over 13 months using various trapping methods (Malaise, emergence, yellow-pan, bait, and light traps, as well as sweeping by hand), finding 4348 Diptera species in 72 families (Borkent et al, 2018;Brown et al, 2018).…”