L. Forró szerk.: Miscellanea Zoologica Hungarica 10. 1995 (Budapest, 1995)

Hutter, G.; Moog, O.: First record of Acentrella sinaica Bogoescu, 1931 in Austria (Insecta: Ephemeroptera: Baetidae)

MISCELLANEA ZOOLOGICA HUNGARICA Tomus 10. 1995 p. 69-72 First record of Acentrella sinaica Bogoescu, 1931 in Austria (Insecta: Ephemeroptera: Baetidae) by G. Hutter and O. Moog (Received January 16, 1995) Abstract: Nymphs of Acentrella sinaica were recorded in Austria for the first time. The specimens were found on cobbles and boulders in a fifth-order mountain stream at an elevation of 1020 m above sea level in the crystalline Tauern Alps of Salzburg. Key words: Insecta, Ephemeroptera, Austria, faunistics Introduction The mayfly fauna of Austria is well documented and known to contain 108 species, 26 of which are from Salzburg (Bauernfeind & Weichselbaumer 1994). The present first record was identified from a very large series of samples collected during the ecological part of a river engineering investigation. This find, from the Lungau in Salzburg, accentuates the necessity of intensive sampling in the course of faunistic surveys: up to the moment when Acentrella sinaica was recorded, 427 quantitative samples had been taken in the time period between 1984-1994. Together with the first record of Arthroplea congener (Moog & Römer 1995) the total species count of Austrian mayflies is now 110. Methods and circumstances of the discovery Quantitative samples across a range of substrate types were collected with a modified Surber-sampler (Type box-sampler, 0.1 m

2 sample area with 100 m mesh size). Species determinations were made by Dr. W. Lechtaler (Vienna): Chironomidae, Dr. M. Car (Brunn): Simuliidae, W. Graf (Vienna): Trichoptera and Dr. F. Sporka (Bratislava): Oligochaeta. The remaining taxa were identified by the authors as well as U. Grasser, K. Grasser, A. Römer and T. Ofenböck. Following the classification system of Moog & Wimmer (1990, 1994), the Taurach river near the village of Tamsweg is a transition zone between a mcta- and a hyporhithral stream of the 5th order with a temperate nivalic flow regime from the cristalline central alps in the "Radstädter Tauern" (Lungau, Salzburg) mountain region. The location lies in the lower reaches of the Taurach river approximately 30 meters before a diversion weir. The stream is approximately 20 meters wide, is graded and lined with rip-rap, creating a relatively homogenous stretch with a water depth of about 50 cm. The substrate sizes range from boulders (20 to 40 cm) to cobble (6 to 20 cm), and the mean current velocity is 0.5 m/s. The elevation is 1020 m above sea level. On the 25th of July 1993, a total of 12 larvae and nymphs were collected in the Taurach river just upstream from its confluence with the River Mur near Tamsweg. The mayflies were found not only in the river bed but also on riparian boulders ( 40 cm). The substrate classification follows the ÖNORM 6232.