The remarkable Anatolian Diagonal is a floristic line crossing Inner Anatolia. The line starts in the southern foothills of the Eastern Black Sea Mountains in Turkey, crosses through Turkey, and then splits into two branches toward the Mediterranean, one through the Amanus Mountains and the other via the Bolkar Mountains. Nearly 400 plant species have distributions largely confined to this line, and many of Turkey's 1,200 endemic species occur only to the immediate east or west of it.
Some of the most interesting plant species in the hotspot are the extremely localized salt plants of Anatolia and Iran. These plants grow in the remaining salt steppes of the Irano-Anatolian closed basins and have adapted to extreme conditions of dry, saline soils with high temperatures and little water.
Hundreds of single-locality endemic plants occur in Turkey, most of them threatened, including many orchids, which are illegally collected in large quantities for the production of a popular traditional drink called sahlep. Because of the rapid decline of orchid species in Turkey, orchid collection has expanded to Iran.
There are more than 360 species of birds regularly occurring in the Irano-Anatolian, although none are endemic. Nevertheless, several globally threatened birds have important breeding populations in the hotspot, including the Endangered white-headed duck (Oxyura leucocephala), Vulnerable great bustard (Otis tarda), Vulnerable marbled duck (Marmaronetta angustirostris) and Vulnerable Eastern imperial eagle (Aquila heliaca). A quarter of the world population of the Critically Endangered sociable lapwing (Vanellus gregarius) stops over in the plateaus of Eastern Anatolia in autumn.
The wetlands of the Tuz, Van and Urumiyeh basins in Turkey and Iran support important breeding colonies of waterfowl, notably the greater flamingo (Phoenicopterus roseus), great white pelican (Pelecanus onocrotalus), Eurasian spoonbill (Platalea leucorodia) and glossy ibis (Plegadis falcinellus).
More than 140 mammals are found in the hotspot, including roughly 10 endemic species. Most of the endemics are rodents, including the Endangered Dahl's jird (Meriones dahli) and Microtus quzvinensis, a recently described vole from northern Iran. Among the most important flagship species in this hotspot is the Critically Endangered Asiatic cheetah (Acinonyx jubatus venaticus).
Reptiles are represented by more than 115 species in the hotspot, including about a dozen endemic species. This includes four endemic and threatened vipers with very restricted ranges: the Critically Endangered Darevsky's viper (Vipera darevskii) from the Djavakhk Mountains in northern Armenia; Endangered mountain viper (Vipera albizona), found in only 20 square kilometers of rocky slope in the Kulmaç Daği of central Anatolia; Critically Endangered Wagner's viper (Montivipera wagneri), from near Lake Urumiyeh in Iran and in Eastern Turkey; and Endangered Latifi's viper (Montivipera latifii), from the Elburz Mountains.
Roughly 20 amphibian species occur in the hotspot, including two endemic and threatened salamanders in the genus Neurergus: the Critically Endangered Kurdistan Newt (N. microspilotus), restricted to the Avroman Mountains on the Iraq-Iran-Turkey border; and Vulnerable Kaiser's Mountain Newt (N. kaiseri), found only in Iran.
About a third of the roughly 90 freshwater fish species in the hotspot are endemic, mainly in closed-basin lakes and rivers. Several of these species are globally threatened, including the Critically Endangered flathead trout Salmo platycephalus.
Although the invertebrate fauna of the hotspot is not well studied, it is known to be particularly rich in butterflies, with at least 350 species. At least 240 of these are found in Turkey, nearly 20 of them endemic. Several globally threatened species occur in this hotspot, including the Endangered, single-site endemic Mesopotamian blue (Polyommatus dama). The hotspot is also known to be the richest part of the Palearctic region for scorpions, with more than 40 described species, at least half of which are thought to be endemic.