Sperchon (Sperchon) thienemanni Koenike, 1907

Fig. 1

Material examined.

Burdur • TR 2-2024 Akyayla, rheocrenic spring, 37.482956°N, 30.326647°E, 22 Apr. 2024, leg. Pešić, Zawal, Gülle & Gülle, 1 ♀ (sequenced) • TR 10-2024, Söbüce, first order stream, 37.287872°N, 30.067743°E, 24 Apr. 2024 leg. leg. Pešić, Zawal, Gülle & Gülle, 2 ♂ (sequenced).

Compared material.

Sperchon thienemanni: The Netherlands • Overijssel, De Lutte, 52.329°N, 6.987°E, 19 May 2012 leg. Smit 2 ♂, 1 ♀, 1 ♂ (NLACA 054-15 / RMNH. ACA. 1072), 1 ♀ (NLACA 055-15 / RMNH. ACA. 1073) sequenced, dissected, and slide mounted (RMNH) • Limburg, Schin op Geul: Genhoes, 50.854°N, 5.858°E, 27 Apr. 2012 leg. Smit 3 ♀ (sequenced; NLACA 426-15 / RMNH. ACA. 851, NLACA 427-15 / RMNH. ACA. 852, NLACA 428-15 / RMNH. ACA. 853), dissected and slide mounted (RMNH) • Limburg, Epen: Terziet, 50.755°N, 5.904°E, 27 Apr. 2012 leg. Smit 1 ♂ (NLACA 422-15 / RMNH. ACA. 847), 1 ♀ (NLACA 421-15 / RMNH. ACA. 846), sequenced, dissected and slide mounted (RMNH).

Remarks.

The specimens sequenced from this study were clustered within two BINs. The first one, BOLD: AES 4247, in addition to two specimens from this study, includes four specimens from Austria. The second BIN, BOLD: AGG 3777, is unique and includes one specimen collected in a rheocrenic spring in this study. The p - distance between these two BINs was estimated at 2.73 %. In the phylogenetic tree, the two above-mentioned BINs of S. thienemanni from Türkiye forms a highly supported clade which is placed (albeit with a low support) as sister to clade grouping specimens of S. thienemanni from the Netherlands. The latter specimens belong to BOLD: ACS 0087.

In all barcoded specimens from southwestern Türkiye as well in examined specimens of S. thienemanni from the Netherlands belonging to BOLD: ACS 0087 and BOLD: ACR 9585, respectively, the excretory pore sclerotized ring was not complete, and was reduced to a separate sclerotized platelets located anterior and posterior of excretory pore, respectively (as illustrated in Fig. 1 B – G). The excretory pore, not completely surrounded by a sclerite ring is well visible in K. Viets’ figure (1936: fig. 146 b), but in recent water mite literature it has not been recognized as an important diagnostic character of the latter species. For example, in a key to Central European water mites (Di Sabatino et al. 2010), the excretory pore of S. thienemanni is described as unsclerotized without mentioning the presence of separate sclerites located anteriorly and posteriorly to the excretory pore which may lead to confusion in the identification of this species

Sperchon thienemanni was considered to be synonymous with S. glandulosus Koenike, 1886 for a long time and was only distinguished as a separate species by Szalay (1941, 1956). Following Bader (1974), and later accepted by Gerecke (1991) and Di Sabatino et al. (2010), the excretory pore in S. glandulosus is completely surrounded by a sclerotized ring.

The applied ASAP procedure (see Fig. 2) grouped together the COI sequences of S. thienemanni - like mites belonging to the following BINs: BOLD: ADV 4077 (specimens from Austria, Switzerland, and Poland available in BOLD database), BOLD: AEO 5165 (specimens from Corsica), BOLD: AER 8061 (specimens from Austria), BOLD: ACR 9585 (specimens from Netherlands), BOLD: AEI 8945 (specimens from Bosnia and Herzegovina), BOLD: ACS 0087 (specimens from Netherlands), BOLD: AGG 3777 (specimen from Türkiye), and BOLD: AES 4247 (specimens from Türkiye and Austria).

The two lineages of S. glandulosus - like mites from Europe were identified as separate MOTUs (hypothetical species). The first MOTU includes Norwegian specimens of two BINs, BOLD: ACQ 0530 (shared with Romania and Belgium) and BOLD: ACR 5909 (shared with Canada), indicating a rather wide, and possible a circumpolar, distribution of this species. The second MOTU represented by BOLD: ADC 0986 includes two specimens from Norway, with a p - distance of 4.99 % to the closest BIN being BOLD: AEZ 0976, which includes one non-identified specimen from Canada. In the phylogenetic tree, the latter BIN is placed as a sister (albeit with a low support) of clades grouping sequences of S. brevirostris Koenike, 1895, indicating that likely this species is phylogenetically closer to the S. brevirostris complex than to the S. glandulosus complex.

Recently, Gerecke et al. (2022) showed that DNA barcodes attributed to Norwegian S. glandulosus grouped into two distinct lineages, suggesting that further revision of Norwegian glandulosus - like mites will result in a revival of the junior synonym S. multiplicatus Thor, 1902, a species described from northern and eastern Norway. However, for a more sound taxonomic revision of S. glandulosus - like mites it is necessary to analyze molecularly more samples from a wider geographical area, preferably by including an additional genetic marker.

Sperchon fundamentalis Bader & Sepasgozarian, 1980, a species originally described from Iran (Bader and Sepasgozarian 1980), but later proposed to be a synonym of S. glandulosus by Esen et al. (2010), differs in the presence of muscle attachment plates on the dorsal and ventral sides of idiosoma (see Bader and Sepasgozarian 1980 for details). Therefore, synonymization of the latter species with S. glandulosus needs to be rejected and S. fundamentalis should be resurrected as a valid species.

Distribution.

Europe (except Scandinavia), Türkiye.