Brown Mayfly
Kageronia fuscogrisea (Retzius, 1783)
Heptagenia fuscogrisea (Retzius, 1783): Russev, 1957: 557; Russev, 1960: 698; Vidinova, Russev, 1997: 142.
Order Mayflies (Ephemeroptera)
Family Flat-headed mayflies (Heptageniidae)
Conservation status: in Bulgaria: Critically endangered CR [B2ac; C2a; D].
General distribution. Norway, Sweden, Finland, Russia, Ireland, England, France, the Netherlands, Germany, Denmark, Poland, the Czech Republic, Slovakia, Serbia, Romania and Bulgaria.
Distribution and abundance in Bulgaria. Reported in the Danube below the mouth of Lom River in 1967 with few specimens [1]. Found also in Ropotamo Valley between 1953 and 1957 [2, 3]. There are no current data of finding the species.
Habitats. This species inhabits limestone lakes and rivers with vegetation on the shore and the river bed. Kageronia fuscogrisea prefers calm sections with a lower speed of water, mainly overgrown with water crowfoots (Batrachium), less often with starworts (Callitriche). It also occurs in puddles near streams and rivers [4, 5]. A rare species.
Biology. One generation yearly. The species overwinters in nymphal stage. The adult flies in May and June. After the hatching, the nymphs develop rapidly in autumn and in early spring [6]. They possess morphological adaptations, e.g. bristles on the legs facilitating swimming; serrate claws for easier catching onto the underwater parts of the plants, etc. If caught by the current, the nymph swims all the time against it until finding oneself in calmer waters. It holds in a stable manner onto the substrate without sticking to it [5]. It feeds on suspended detritus or grinds algae and other microflora of hard substrates [7].
Similar species. Heptagenia sulphurea, from which it differs in the shape of tracheal gills of the nymph and in the morphology of the male genitalia.
Negative factors. The main threat for the species is destruction of the natural habitats caused by the cleaning of river banks overgrown with vegetation, river regulation as well as water pollution.
Conservation measures taken. None.
Conservation measures needed. Cleansing the waters and keeping them clean, restoration of the natural living conditions of the species, conservation of the vegetation near the banks of rivers and lakes.
References. 1. Vidinova, Russev, 1997; 2. Russev, 1957; 3. Russev, 1960; 4. Macan, 1961; 5. Madsen, 1968; 6. Brittain, 1974; 7. Elliot et al., 1988.
Author: Yanka Vidinova
