S. Mahunka szerk.: Folia Entomologica Hungarica 44/1. (Budapest, 1983)

Individual variation in wild and laboratory reared specimens of Tarsonemus nodosus Schaarschmidt, 1959 (Acari: Tarsonemidae) By M. KALISZEWSKI, Z. W. SUSKI and S. REJMAN (Received December 1, 1982) Abstract: Infraspecific variability of morphological characters was investigated in two populations of Tarsonemus nodosus Schaarschmidt. Males are more variable than females, greater variability was shown among laboratory reared mites than among wild ones. The most variable character appears in the measurements of leg IV of a male. Taxonomic significance of certain characters is discussed in realtion to their variability. So far, no research on the variability of measuring characters of mites of the Tarsonemidae family has been carried out. There is a great demand for this type of research, as measuring characters has been broadly used for differentiating specimens in this group of animals. Searching for measuring characters accounts for the fact of a relatively simple structure of Tarsonemidae and the scantiness of other taxonomic characters connected with it. Quite often it cannot be easily decided whether the examined specimen of this family still belongs to the given species or whether it should be regarded as new a new one, due to the changes in measuring. The authors have investigated the variability of Tarsonemidae on the basis of one of most common species in Europe Tarsonemus nodosus Schaarschmidt, 1959. It has been described from specimens collected from Fraxinus excelsior, Crataegus sp. and mole nests at various dates in 1950-51 in Erlangen (FRG) (SCHAARSCHMIDT, 1959). Later SUSKI (1965) described it as Tarsonemoides poroi from specimens collected on apple trees at several localities in Poland, which after an exchange and re-examination of the type specimens, proved to be a junior synonym of T. nodosus (SUSKI & SCHAARSCHMIDT, 1971). The species was found to occur abundantly on apple trees in Poland (SUSKI, 1967, 1972b) and Germany (KARG, 1971). Specimens of this mite were found on apples in the Netherlands and the Soviet Union (regions of Moscow, Leningrad and the Ukraine (SUSKI, 1967, 1972b, LIVSHITS et al. 1979, VOYTNICH, personal communication). It was found also on meadow grasses in Germany (WETZEL, 1969). Under laboratory conditions it propagated on Hormodendrum resinae (Linder), Altenaria tenuis (Nees.) and other unidentified fungi (SUSKI, 1967, 1972a). Among the specimens examined a considerable variability was noted in size and in certain morphological features. It was particularly apparent among laboratory reared males since extreme morphotypes occurred within the offspring of the same female. The present research was initiated to clarify whether the variability observed was induced by breeding of the mites under the condition of strongly limited space and population size or it was a part of natural variability of the