Thinoseius spinosus (Willmann, 1939)

AndrianovK, Boris V., MakarovaK, Olga L. & GoryachevaK, Irina I., 2024, Genetic variability of abundant littoral species of mesostigmatic mites (Acari, Mesostigmata) with different distributions from the seashores of Eurasia, Acarologia 64 (4), pp. 1191-1212 : 1202

Thinoseius spinosus and other species of the genus

In addition to the widespread Holarctic species T. spinosus , further three species of the genus Thinoseius with narrower geographic distributions have been found in the littoral zones of Eurasia: T. fucicola ( Halbert, 1920) , T. occidentalipacificus Klimov, 1998 ; and Thinoseius

cf. kargi Hirschmann, 1966. The variability of ITS fragments of all four species is presented in Figure 6 . Distinguishing the species is not difficult. Three clades are observed with good bootstrap support. Two clades correspond to the species T. spinosus and T. occidentalipacificus . The third clade combines ITS sequences of T. fucicola and Thinoseius cf. kargi . Thinoseius occidentalipacificus mites are known from the Pacific region ( Klimov 1998 ; Takaku 2000 ; Makarova 2019), T. fucicola from the shores of the northern and southern seas of Europe ( Remmert 1956 ; Evans 1969 ; Bregetova 1977), and T. cf. kargi from the coasts of the Mediterranean and Black seas ( Hirschmann 1966 ; Avdonin 2002). Both latter species show a single genotype of the ITS fragment, one different from other genotypes found among Thinoseius species.

the genus Dermanyssus ( Dermanyssidae ) and Eviphis ostrinus ( Eviphididae ) were used as out-groups to root the tree. The sequence taken from GenBank is marked with GenBank ID number. The length of the aligned sequences is 669 nucleotide sites. The newly obtained sequences are denoted with color labels. The legend for color labels is given in Figure 2 .

When studying the ITS sequences of 52 specimens of T. spinosus from 17 localities, four genotypes were found ( Table 3). To analyze the intraspecific variability of this species, we constructed a median network of genotypes ( Figure 7 ). Intraspecific variability of T. spinosus is again star-shaped. The most abundant genotype, marked with number (I), occupies the central position in the median network of genotypes and thus it is considered ancestral, at least so for the modern European super-population. We found genotype (I) in four of five larger regions, except for the Pacific region, where it is replaced by genotype (II).

Special genotypes of T. spinosus different from the central genotype (I) are found only in the regions of the Pacific and Arctic oceans, while across the vast areas covering the shores of the Baltic, Black, Azov and Caspian seas T. spinosus appears to be monomorphic. The value of the selective neutrality test (Tajima’s D) does not reveal any selection effect on the T. spinosus population ( Table 4).

Figures

Figure 2 NJ cladogram of ITS genotypes of the littoral mite,Phorytocarpais kempersi. ITS geno-

Figure 6 NJ cladogram of ITS genotypes of the genusThinoseius. ITS genotypes of two members of

Figure 7 Median network of ITS genotypes of the littoral mite,Thinoseius spinosus. The size of the circles is proportionate to the number of individuals of given genotype. The dashes indicate mutations separating the genotypes. The length of the aligned sequences is 663 nucleotide sites. Number of segregating sites 6. The numbers in the circles indicate the different genotypesT.of spinosus. Sample characteristics are given in Table 3.