Halolaelaps orientalis (Blaszak and Ehrnsberger, 1998)

Halolaelaps orientalis and H. celticus

When analyzing the sequences of 20 specimens of H. orientalis , six ITS genotypes were obtained ( Table 2). However, based on morphological characters, we have discovered three possible cryptic species close to H. orientalis . They were revealed in the Black Sea (sp. 1) and the seas of the Pacific Ocean (sp. 2, 3) and have some genetical distinctions ( Figure 5 View Figure 5 ).

The variability of the ITS fragment of all five distinguished members of the celticus -group analyzed, and of the congeneric Halolaelaps punctulatus (Leitner, 1946) , is presented in

Figure 4 View Figure 4 . Three clades with 99% and 100% bootstrap support correspond to the species: H.

celticus, H. punctulatus and a complex of closely related species, Halolaelaps spp. , related to

H. orientalis . To analyze the genetic structure of this complex of close species, we constructed a median network of genotypes ( Figure 5 View Figure 5 ). This median network is star-shaped, this being characteristic of species that may have relatively recently gone through a stage of an explosive range expansion. The central position in this median network of genotypes is occupied by genotype (I), which is found in the Azov-Black Sea region and in the Pacific region and belongs to H. orientalis proper. The remaining genotypes have a narrower geographic distribution and are likely to have derived from genotype (I). Among the intertidal mite species we studied, H.

orientalis is the most variable ( Table 4). As in the case of Phorytocarpais kempersi , the value of the selective neutrality test (Tajima’s D) fails to indicate the presence of any discriminatory pressure on its modern population. We found numerous demes of H. orientalis on the coasts of the Mediterranean, Azov and Black seas, as well as the Russian Far East (Sea of Japan).

H. orientalis was not found on the coasts of the Arctic Ocean seas, where it is replaced by the closely related species, H. celticus . We were able to obtain genetic material of H. celticus from remote populations: the shores of Iceland, Solovetsky Islands, Kola Peninsula, and Kanin

Peninsula. The ITS fragment studied turned out to be monomorphic in our sample H of. celticus

(10 specimens from five localities), but separated from H. orientalis by six phylogenetically significant substitutions.

So, besides well distinguished species H. orientalis and H. celticus , some probably new species were found within the celticus -group, namely: Halolaelaps sp. 1 [“gracilis”] from the northeastern Black Sea coast, Halolaelaps sp. 2 [“elongatus”] from Iturup Island, Halolaelaps

sp. 3 [“extremiorientis”], from the southern coast of Chukotka and Kamchatka peninsulas.

All these forms have unique ITS genotypes ( Figure 5 View Figure 5 ). The genetic evidence, together with some morphological differences, support the assumption of species rank status for these three species. Further data are required to clarify this proposal. Carriers of ITS genotypes I–VI, on the contrary, showed no clear morphological differences.