Thyasides dentatus (Thor, 1897)

Pešić, Vladimir, Mumladze, Levan & Zawal, Andrzej, 2023, New records and first DNA barcodes of water mites (Acari, Hydrachnidia) from Georgia, Ecologica Montenegrina 67, pp. 91-100 : 94

Thyasides dentatus (Thor, 1897) ( Figs. 1 A-B)

Material examined — GEORGIA, unnamed pond (Javakheti), 41.4001° N, 43.6723° E, 2261 m asl., 16 May 2016, leg. Mumladze, Japoshvili, Bikashvili, Shubitidze 1♀ (sequenced; voucher ID: CCDB 41822 D11), dissected and slide mounted .

Remarks — The specimen from Georgia molecularly analyzed in this study match the description of Thyasides dentatus , a species known from central, northern and north-eastern Eurtope ( Di Sabatino et al. 2010). The genus Thyasides was established by Lundblad (1926) for the species Thyas dentata Thor, 1897 . Later on, Habeeb (1958) described T. sphagnorum Habeeb, 1958 from New Brunswick, Canada. The genus is primarily diagnosed by the shape of frontal shield (anteriorly convex due to the projecting frontal eye sclerite, posteriorly concave or straight between the projecting frontalia) and the median eye with two pigment spots (Di Sabatino et al. 2020). However, occasionally, the frontal eye can be separated from the frontalia and the latter is visible as a transverse platelet posterior to the frontal eye ( Di Sabatino et al. 2010). Di Sabatino et al. (2010) and Smit (2020) stated that the genital flaps in Thyasides are covered by numerous, uniform short setae. This statement is based on figure 8-5 c in Di Sabatino et al. (2010) (the same figure is reproduced in Smit 2020, fig. 392) which should represent the female genital field of T. dentatus . The latter illustrated specimen represent Parathyas bruzelii ( Lundblad, 1926) (Gerecke pers. communication) a species having a numerous setae on the male genital flap surface. Therefore, the statement given in the genus diagnoses in Di Sabatino et al. (2010) and Smit (2020) on the presence of numerous uniform short setae on genital flaps is erroneous. In our female, as in Lundblad (1927) there are only a few setae on the genital flap surface ( Fig. 1A ).

The sequenced specimen of T. dentatus from Georgia forms a distinct BIN ( BOLD: AEO 0651). The p -distance between the latter BIN and its nearest neighbour, BOLD:ACW5624, which includes specimens from Canada identified as Thyasides sp. (probably T. sphagnorum ) is estimated at 7.56%.

Habitat in Georgia — Temporary vernal pools, with cold water and absence of aquatic vegetation; heavily used by sheep and cattle ( Fig. 2A ).

Figures

Figure 1. Thyasides dentatus (Thor, 1897), ♀, unnamed Pond (Javakheti), Georgia. Photographs of genital field (A) and palp (B).

Figure 2. Photographs of selected sampling sites: A – unnamed pond (Javakheti); B – Lake Saghamo; C – pond near Ozaani; D – Paravani Lake. Photos by L. Mumladze.