Fauna and systematics of chiggers of the minuta group, genus Neotrombicula (Trombiculidae)

A.A. Stekolnikov

Parazitologiya, 29(4): 250-266 (1995) (In Russian, English summary).

S U M M A R Y

Taxonomical analysis of minuta-group in the genus Neotrombicula has been carried out. Descriptions of 6 species has been corrected. The main corrections are as follows. 1). In N. scrupulosa fD=2H-(6—11)-(6—9)-(6—8)-4-... The common fD=2H-8-6-6-4-6-2. 2). N. lubrica differs from N. minuta first of all in the number of setae in the 4th dorsal row and in the first rows of V, and also in more dense punctation of scutum. 3). N. irata has fD=2H-6-6-6-2-6-2 but not 2H-6-6-6-4-4-4 as in description. 4). Both N. irata and N. lubrica has SB anterior to PL, and in N. lubrica it is more anterior than in N. irata.

One new species, N. dimidiata sp.n. is described from rodents collected in Western Kopetdagh (Turkmenistan) and Northern Tadjikistan. The new species is similar to N. minuta but differs in presence of 2 setae in the 4th dorsal row vs. 4 in N. minuta, lesser number of setae in the anterior rows of V (8 vs. about 12 in N. minuta), greater values of D and V mean lengths (35—43 vs. 33—35, and 32—39 vs. 27—30 in N. minuta, respectively), and by greater Ip (847—982 vs. 786—877 in N. minuta). The new species clearly differs from N. lubrica in the shape of the scutum and in more sparse punctation of it.

For N. scrupulosa an analysis of geographical variability has been carried out. The methods used had been previously devised for ticks (Filippova e.a., 1995). Nonmetric multidimensional scaling on 8 characters (AW, SB, PSB, SD, AP, AM, D[mean] and NDV) has been used to obtain the picture of relative distances between samples. Almost all measurable characters, fD and NDV in the species show a significant variability, but intervals of their values for different populations are overlapped. Comparing the diagram showing relative distances between samples from different localities (Fig. 4) and the picture of their disposition on the map (Fig. 5), one can conclude that it is a case of a cline, stretching approximately in the latitudinal direction.

For N. corvi, N. lucida, N. scrupulosa and N. lubrica new hosts and/or new localities are pointed out. The distribution of N. minuta is probably restricted in the Southern Ukraine. Steppes and similar biotopes in Caucasus, Bashkiria, Northern, Eastern and Southern Kazakhstan, Altai Territory, Tuva and Mongolia are inhabited by another species, N. scrupulosa. In the mountains of the Middle Asia minuta-group is represented by several species appeared to be local.