Phorytocarpais kempersi (Oudemans, 1902)

Phorytocarpais kempersi (Oudemans, 1902)

This species was earlier assumed to be cosmopolitan in distribution, although its absence from the shores of the Caspian Sea, the Aral Sea and Arctic Siberia had been reported simultaneously ( Tikhomirov 1977). And there still are no records outside the Holarctic. According to our data, P. kempersi is an abundant species in sea debris on the shores of the middle and southern parts of the Caspian Sea (O.L.M.: personal observations). It is common everywhere, including the Atlantic and Pacific coasts of North America ( Krantz 2016 ; material from the Canadian National Collection of Insects, Arachnids and Nematodes, accessed 7 October 2020, curator W. Knee; O.L.M. unpublished data). Phorytocarpais kempersi appears first in algal emissions, being most abundant in the early stages of their decay succession ( Strenzke 1963 ; Makarova and Petrova-Nikitina 2008 ; Bizin and Makarova 2022). Phoresy of its deutonymphs on “larger inhabitants of rotting algae carried by water” has also been reported ( Tikhomirov 1977), and the possibility of dispersion on sea-washed algal debris in the summer conditions of the North, Black and White seas has been proven experimentally ( Pugh and King 1985 ; Avdonin 1999 ; Makarova and Petrova-Nikitina 2008). Moreover, in a special experiment conducted in August 2008 in the White Sea, submerged algae were shown to retain about 80% living P. kempersi individuals for at least 5 days (O.L.M.: personal observations). The species has the widest diet among the study littoral mite species. Its sharp increase in numbers was observed when feeding on nematodes, Sphaeroceridae larvae and small crustaceans ( Avdonin 2002), but P. kempersi also consume enchytraeids, dead and living adults of Diptera , juvenile oribatid and mesostigmatic mites, including individuals of their own species ( Pugh and King 1985 ; Avdonin and Striganova 2004). Simultaneously, 4− 7 eggs can mature inside the female (O.L.M.: personal observations). Individuals from the White and Black seas successfully interbreed with each other ( Avdonin and Striganova 2004).