Sperchon ( Hispidosperchon ) clupeifer Piersig, 1896

Kolesnikov, Vasiliy B. & Stolbov, Vitaly A., 2025, Review of the genus Sperchon Kramer, 1877 (Acari, Hydrachnidia: Sperchontidae) from Russia, Zootaxa 5666 (1), pp. 53-73 : 57

25. Sperchon ( Hispidosperchon) clupeifer Piersig, 1896

Syn.: Sperchon elegans Thor, 1898 ; Sperchon thori Koenike, 1901 ; Sperchon koenikei Walter, 1907 ; Sperchon undulosus Koenike, 1908 .

Distribution: European part: Republic of Karelia ( Sokolow, 1930), Kola Peninsula ( Sokolow, 1940; Shubina & Tsember, 2017), Leningrad Region ( Sokolow, 1936); Tver Region ( Thor, 1923; Sokolow, 1940); Kaluga Region ( Jankovskaja, 1964); Yaroslavl Region ( Zhavoronkova, 2000; Tuzovskij, 1977; 1996; Zhavoronkova et al., 2023); Samara Region ( Tuzovskij, 2007); Voronezh Region ( Silina et al., 2014); Komi Republic, Arkhangelsk Region ( Shubina & Tsember, 2017); Sverdlovsk Region ( Klimov et al., 2022; Stolbov et al., 2024): Caucasus: Krasnodar Krai ( Jankovskaja, 1959); Western Siberia: Tyumen Region ( Stolbov, 2010)

Note: Wainstein (1981) suggested that S. clupeifer may have three subspecies: the nominate one, S. clupeifer plumifer Thor, 1902 and S. clupeifer anulatus Wainstein, 1981 . He saw differences between these subspecies only in the presence of a chitinous plate around the excretory pore and the degree of plumoseness of the dorsal setae of the legs and their frequency. Since the presence or absence of a chitinous plate around the excretory pore is a species characteristic ( Di Sabatino et al. 2010), it is impossible to agree with the subspecific status of S. plumifer (now recognized as a junior synonym of Sperchon hispidus Koenike, 1895 ). Sperchon clupeifer and S. hispidus are quite clearly distinguished by this feature, as well as by the length/height ratio of P-4 and by the shape of the dorsal shields in the male ( Di Sabatino et al. 2010). The degree of plumoseness of the dorsal setae of the legs also differs, but not always obviously ( Di Sabatino et al. 2010). The third subspecies S. clupeifer anulatus also should it be considered a probably full species to the difference from S. clupeifer in the sclerotization of the excretory pore. In the density of the plumose dorsal setae of the legs and sclerotization of the excretory pore, it is closer to S. hispidus . But it differs from it in the degree of plumoseness of these setae. Moreover, it differs from the two species in the proportions of P-4 - it is narrower in S. clupeifer anulatus (~8.0) vs. S. hispidus (4.5 – 5.4) vs. S. clupeifer (5.4 – 6.5). Thus, S. clupeifer anulatus can probably be recognized as a separate species, but the lack of information on males does not provide complete certainty. A re-examination of the type material of S. clupeifer anulatus is required and more material is needed, including males.