CHAPTER 5How many Lepidoptera species are waiting to be discovered in Iran? An estimation of the total lepidopteran fauna

Abstract

© Staatliches Museum für Naturkunde Stuttgart Identifying knowledge gaps and highlighting the less explored areas of Iran were two of the major purposes of the “Lepidoptera Iranica” project. In that context, it was important to estimate the number of unidentified or undescribed species as well as the cryptic lepidopteran diversity of the country. It is possible to estimate the total Lepidoptera fauna of Iran by comparing the Iranian diversity of certain well-known groups with the European diversity of those same groups, as Europe has arguably the best-known Lepidoptera fauna in the world for a large surface area. The total number of valid Lepidoptera species (4,812) listed in this catalogue (rajaei et al. 2023) must be considered underestimated. Although some groups, such as Papilionoidea (nazari 2003; tshiKOLOvets et al. 2014) and Zygaenidae (KeiL 2014; hOfmann & tremewan 2017, 2020), have been extensively researched and their Iranian faunas are considered to be well known, others, e.g., Microlepidoptera, are generally still poorly known. The Lepidoptera fauna of Europe, on the other hand, has been the subject of intense interest since the time of Linnaeus, i.e., for more than 260 years, and is considered relatively well known (e.g., KarshOLt & razOwsKi 1996). The Fauna Europaea project (KarshOLt & nieuKerKen 2011) assembled a database of the scientific names and distributions of European Lepidoptera, but the most recently updated dataset (version 2.4) dates back to 2011. The most updated source of taxonomic information on the Lepidoptera fauna of Europe is the Lepiforum web portal (https:// lepiforum.org/) (rOdeLand et al. 2006–2022), which lists the total number of species in each family-group taxon. One important factor to consider is that Europe is over six times larger than Iran and is significantly different in terms of habitat and geology. Also, due to the more easterly and southerly geographic position of Iran and to the different paleo-historical events it was subjected to, there are important zoogeographical dissimilarities between the two. In Iran, high mountains create a barrier in the west; the eastern regions are covered by infertile, salty deserts; a narrow, fertile strip borders the Caspian Sea in the north; and lowlands rim the Persian Gulf in the south. Many authors have estimated global and regional Lepidoptera biodiversity based on a variety of methods. One method of estimating lepidopteran species richness is by faunal comparisons between the number of described species of butterflies (i.e., superfamily Papilionoidea) and that of moths (e.g., LafOntaine & wOOd 1997). Global butterfly diversity consists of 18,732 described species (nieuKerKen et al. 2011), representing about 90% of an estimated total of 20,813 species (rOBBins & OpLer 1997; pOgue 2009). In well-collected areas in northern Europe and Canada (e.g., Ottawa, Ontario), the butterfly fauna constitutes 4–5% of all lepidopteran species (LafOntaine & wOOd 1997; pOgue 2009). In the Nearctic Realm, the butterfly fauna constitutes 6% of all lepi dopteran species (OpLer & warren 2003; warren et al. 2012; peLham 2022). Technically speaking, using faunal comparisons fails to give an accurate estimate of world lepidopteran species richness at a global scale (pOgue 2009), but can be a good way of estimating the species richness of a local area or region. Here, we attempt to provide a gross estimate of the number of Lepidoptera species potentially occurring in Iran by using such faunal comparisons, with estimated total species numbers extrapolated based on a statistical comparison of the European and Iranian species richnesses of the exhaustively studied Papilionoidea and Zygaenidae.