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New species and sympatric relations of the chigger mite species group talmiensis (Trombiculidae, Neotrombicula)

A.A. Stekolnikov

Parazitologiya, 35(6): 496-518 (2001) (In Russian, English summary).


A revision of chigger mite species being closely related to Neotrombicula talmiensis (Schluger, 1955) has been performed. Two new species are described: N. pontica sp. n. from Krasnodar Territory (Western Caucasus) and N. sympatrica sp. n. from Krasnodar Krai, Daghestan, Tuva, Armenia, Kyrgyzstan, and Turkey (Rize Province). N. pontica sp. n. is closely related to N. carpathica Schluger et Vysotzkaya, 1970 and differs from this species by the larger number of idiosomal setae (NDV = 75—99 vs. 63—77), shorter legs (lp = 782—847 vs. 844—920, TaIII = 67—74 vs. 70—80), lesser m-t (0.180 vs. 0.192), slightly lesser scutum and slightly longer setae. N. sympatrica sp. n. is closely related to N. carpathica and differs from this species by the longer scutal and idiosomal setae (PL = 67—78 vs. 57—69, H = 65—75 vs. 57—68, Dmin = 43—52 vs. 39—48, Dmax = 61—70 vs. 54—64), longer legs (lp = 892—973 vs. 844—920, TaIII = 77—86 vs. 70—80) and lesser m-t (0.168 vs. 0.192). N. carpathica is reported for the first time from Northern Caucasus (Karachai-Cherkess Republic, Kabardino-Balkaria, North Ossetia); N. taimiensis is reported for the first time from Khakasia.

Data on joint occurrence of 3 species are reported. The 3 types of sympatric pairs of the species have been found in the Western Caucasus: 1) N. pontica sp. n. and N. sympatrica sp. n., 2) N. sympatrica sp. n., and N. carpathica, 3) N. pontica sp. n., and N. carpathica. Differences between species in those localities, where the joint occurrence was recorded, have been analysed. Sympatric relations between N. sympatrica sp. n. and N. carpathica are characterized by increased value of some general diagnostic characters of these species, such as the length of idiosomal setae and length of legs. In different sympatric localities, different characters play main distinguishing role. Besides that, some local features appear in certain species of sympatric pairs (narrow scutum in 3 samples of N. carpathica, numerous idiosomal setae in 1 sample of N. sympatrica), which differ the populations of the sympatric pair, and also discriminate such aberrant group from other material of the same species.

Functions produced by the method of discriminant analysis are proposed for the purpose of diagnostics in talmiensis group. Tests for assumptions of discriminant analysis, such as normality and homogeneity of variances, have been performed beforehand. Verifications of the functions on test samples demonstrated the good quality of its working. Key to species using discriminant functions has been constructed.

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