Big Neoephemerid Mayfly
Neoephemera maxima (Joly, 1870)
Caenis maxima (Joly, 1870):Russev, 1971: 112; Neoephemera (Leucorhoenanthus) macedonica (Ulmer, 1920): Russev, 1971: 112.
Order Mayflies (Ephemeroptera)
Family Large square-gilled mayflies (Neoephemeridae)
Conservation status: in Bulgaria: Critically endangered CR [A2a; B1ab(iv); D; E].
General distribution. France, Belgium, Poland, Lithuania, Hungary, the northern part of the Balkan Peninsula, the Ukraine, European Russia.
Distribution and abundance in Bulgaria. Few specimens have been recorded in the Tundzha River between Slivenski Bani and Yambol in 1955 and in the Mesta River near Gotse Delchev in 1973 [1]. The species was not found during the investigations of the Tundzha in 1981 [2] and 2006 [unpublished data]. There are no current data of finding the species also in its locality in the Mesta River [unpublished data].
Habitats. The nymph inhabits the lentic zone in rivers and streams where the current is weak and the substrate is covered with detritus, algae, mosses and other macrophytes in summer [3]. It occurs around water plants, among the intertwined roots of seed plants, branches or deposits, under large flat stones, and often among mosses (Fontinalis antipyrica) [4].
Biology. The nymphs crawl slowly and are bad swimmers. The last instar nymphs develop in May and June [3], the adult usually emerges on the following day after the appearance of the subimago. A mass flight of adults over the surface of large rivers is observed early in the morning [5]. The females lay eggs on the surface of the water at sunrise [6].
Negative factors. Destruction of the natural habitats caused by man. Extraction of inert materials from the bottoms of rivers. Neoephemera maxima is a markedly sensitive species to the cleanliness of the river water and hence is especially vulnerable to pollution with industrial and home waste waters.
Conservation measures taken. None.
Conservation measures needed. Prevention of pollution in the middle and lower courses of the larger rivers, where there exists a possibility for finding the species. Restoration and protection of the natural living conditions in its potential habitats.
References. 1. Russev, 1971; 2. Janeva, Russev, 1985; 3. Jazdzewska, 1975; 4. Fontan et al., 1999; 5. Bae, McCafferty, 1998; 6. Kazlauskas, 1959.
Author: Yanka Vidinova
