| Abstract: | Aberrations (quantitative chaetotactic deviations, i.e. decreasing or increasing of setae numbers and variations in arrangement of setae) and anomalies (qualitative chaetotactic deviations, for example, partial reduction of scutum, shortening of a seta more than 1.5-2 times, merging of setae) were recorded for 13 taxonomically important morphological structures in the chigger mite species Neotrombicula sympatrica Stekolnikov, 2001. 3308 specimens were studied as a total. 17.2% of them had various morphological deviations. The most common types of aberrations were observed in the number and positions of genualae I (94 specimens), AM seta (79 spec.) and sternal setae (77 spec.). The aberrations of sternal and coxal setae were usually interrelated: the sternal seta was "transferred" from the sternal area onto the coxa, or the other way round take place. The specimens having aberrations of sternal setae were twice as numerous as the specimens with aberrations of coxal setae (77 against 35). The specimens with aberrations of dorsal setae and mastitarsala were very rare (2 spec. each). Among anomalies, the presence of nude galeal seta (91 spec.) and scutal anomalies (66 spec.) were prevalent. The most frequently one form of deviation only was observed in one specimen of N. sympatrica. Nevertheless, the specimens simultaneously having several aberrations or anomalies were also found. 17 types of such combinations were observed, that counts 20.6% of all specimens with deviations. Symmetric deviations, namely the presence of two nude galeal setae (31 spec.), presence of 2 genualae on both legs I (4 spec.), presence of 2 AM (2 spec.) and symmetric reduction of scutal angles (1 spec.), sometimes cause troubles in diagnostics. The quarter of variance in N. sympatrica and in the species N. monticola Schluger et Davydov, 1967 formerly studied by the author turned out as almost identical. The specimens with deviations counted 14.5% of all studied specimens in the latter species. However, the structures of variance in these species is different. In N. monticola, the aberrations of humeral setae were dominant (71.6%) (Kharadov, Chirov, 2001), while in N. sympatrica, the aberrations of other structures were prevalent: genualae I (24.8%), AM (20.9%) and sternal setae (20.4%). |
