A revision of the extant species of Theodoxus (Gastropoda, Neritidae) in Asia, with the description of three new species Author Sands, Arthur F Justus Liebig Univrsity Giessen, Giessen, Germany Author Gloeer, Peter Biodiversity Research Laboratory, Hetlingen, Germany Author Guerlek, Mustafa E Mehmet Akif Ersoy niversity, Burdur, Turkey Author Albrecht, Christian Justus Liebig University Giessen, Giessen, Germany Author Neubauer, Thomas A Justus Liebig University Giessen, Giessen, Germany & Naturalis Biodiversity Centre, Leiden, Netherlands text Zoosystematics and Evolution 2020 96 1 25 66 http://dx.doi.org/10.3897/zse.96.48312 journal article http://dx.doi.org/10.3897/zse.96.48312 1860-0743-1-25 F2C8585A1268443693348B64AE20F6EE 4EDA9B5B777551B7BBB0152DD188E5EF Theodoxus major Issel, 1865 Figure 19A -Zb Neritina liturata Eichwald 1838 : 156-157; Martens 1879 : 223-224, pl. 21, figs 24-26; Kobelt 1899 : 8, pl. 212, fig. 1336 ( non Neritina liturata Schultze, 1826). Theodoxus schirazensis var. major Issel 1865 : 24; Issel 1866 : 408. Neritina Schultzii Grimm 1877 : 77-78, pl. 7, fig. 5, pl. 8, fig. 16. Neritina Schulzii [sic]: Martens 1879 : 239-240, pl. 23, figs 13-16. Theodoxus pallasi Lindholm 1924 : 33, 34 (nom. nov. pro Neritina liturata Eichwald, 1838, non Schultze, 1826); Starobogatov 1974 : 255-256, text fig. 224; Akramovskiy 1976 : 88, text fig. 23, pl. 1, figs 1, 2; Anistratenko et al. 2017 : 221, figs 4, 7, 10, 11; Neubauer et al. 2018 : 48-51, figs 4A-F; Wesselingh et al. 2019 : 64-65; Gloeer 2019 : 48-49, fig. 36. Theodoxus (Theodoxus) pallasi var. nalivkini Kolesnikov 1947 : 106, 110. Theodoxus (Ninnia) schultzi [sic] var. jukovi Kolesnikov 1947 : 106, 110. Theodoxus zhukovi [sic]: Starobogatov 1974 : 255, text fig. 223. Theodoxus astrachanicus Starobogatov in Starobogatov et al. 1994 : 8-9, fig. 1(1-2); Degtyarenko and Anistratenko 2013 : 22-23, pl. 1, fig. 2a-c. Theodoxus (Theodoxus) schultzii : Zettler 2007 : 249-250, figs 4a-h, 5a-h; Vinarski and Kantor 2016 : 157. ? Theodoxus doriae : Mansoorian and Samaee 2012 : 44-45 (partim, only material from Gilan and Mazandaran provinces; non Theodoxus doriae Issel, 1865 [= T. pallidus ]) ? Theodoxus euphraticus : Mansoorian and Samaee 2012 : 61 (partim, only material from the Khorasan provinces; non Neritina euphratica Mousson, 1874 [= T. jordani ]) Theodoxus fluviatilis : Gloeer and Pesic 2012 : 16-17 (partim, only Khorrasan material; non Nerita fluviatilis Linnaeus, 1758). Theodoxus (Theodoxus) astrachanicus : Vinarski and Kantor 2016 : 155-156. Theodoxus (Theodoxus) pallasi : Vinarski and Kantor 2016 : 156-157 (and synonyms therein). Theodoxus schultzii : Wesselingh et al. 2019 : 66; Gloeer 2019 : 52, fig. 40. Theodoxus major : Sands et al. 2019b : 3, fig. 1. Type locality. Lake Sevan, Armenia. However, Akramovskiy (1976) suggested the type locality given by Issel (1865) was erroneous and should be Yerevan in Armenia. Type material. The syntypes of T. schirazensis var. major are supposed to be stored in MRSN , but the collection is inaccessible at the moment due to renovation and restoration of the museum (E. Gavetti pers. comm. 09/2019) . The lectotype of N. liturata and T. pallasi (designated by Starobogatov et al. 1994 ) is stored in ZIN (coll. no. 54547/63) . Twenty syntypes of N. schultzii are stored in ZIN (coll. no. 6214/5) and a single in ZMD (coll. no. ZB-M W. Dyb. 71; see Anistratenko et al. 2018 ) . Remarks. Wesselingh et al. (2019) reviewed the taxonomy of the Pontocaspian Theodoxus spp. They showed that N. liturata Eichwald, 1838 (described from Derbent, Dagestan, Russia, north-western Caspian Sea) was invalid as a junior primary homonym of N. liturata Schultze, 1826 (described from the Americas) and was replaced by Lindholm (1924) with T. pallasi Lindholm, 1924. Moreover, they supported the synonymy of T. astrachanicus Starobogatov in Starobogatov et al. 1994 with T. pallasi ( Anistratenko et al. 2017 ). Wesselingh et al. (2019) additionally suggested T. schultzii (Grimm, 1877) and T. major (the latter originally described as a variety of the unavailable name T. schirazensis ) may additionally be conspecific with T. pallasi given morphological similarities. However, Wesselingh et al. (2019) refrained from synonymising T. major , T. pallasi , and T. schultzii , pending molecular support. This was provided recently by Sands et al. (2019b) , who corroborated the synonymy of T. astrachanicus , T. major , T. schultzii , and T. pallasi (also see Fig. 2 ). As already argued by Wesselingh et al. (2019) , the name T. major has priority. There is large intraspecific morphological variability within this species, especially regarding the radula, shell shape and periostracum colouration ( Zettler 2007 ; Anistratenko et al. 2017 ; Fig. 19 ). For example, specimens from deeper parts of the Caspian Sea ( T. schultzii -morphotype) may lack colouration and have a broadened columellar plate making the shell look somewhat flattened ( Zettler 2007 ; Fig. 19 ), while shoreline samples ( T. pallasi -morphotype) lack this broadened columellar plate and display clear, black diagonal banding patterning (Fig. 19 ). Inland specimens ( T. major -morphotype) from Iran and Armenia tend to be dark and with a less distinct banding pattern (Fig. 19 ). The operculum of this species is somewhat similar to those of T. pallidus , T. fluviatilis , and T. velox with a strong rib-shield and no pseudo-apophysis (Figs 9 , 10 , 19 , 20 , 22 ). It is not surprising that molecular data of material from locations in Khorrasan province studied by Gloeer and Pesic (2012) and identified as T. fluviatilis conforms to T. major ( Sands et al. 2019b ; Fig. 2 ). Akramovskiy (1971) already suggested that specimens considered T. subthermalis [= T. fluviatilis ] from Armenia represented black-coloured morphotypes of T. pallasi [= T. major ]. However, T. major only shares a close phylogenetic relationship with T. pallidus and likely diverged from their common ancestor during the Pleistocene ( Sands et al. 2019b ; Fig. 2 ). Figure 19. Theodoxus major Issel, 1865. A , B . Specimen ( T. pallasi -morphotype) collected in the Caspian Sea, offshore from Aktau, Kazakhstan ( UGSB 20712); C , D . Specimen ( T. pallasi -morphotype) collected in the Aral Sea, Kazakhstan in 1979 ( UGSB 19129); E - H . Specimen ( T. pallasi -morphotype) from the Shahpol River, Aliabad Askar Khan, Iran ( UGSB 18091); I - K . Specimen of T. major collected at the outflow of Lake Akna, Aknalich, Armenia ( UGSB 20482); L - N . Specimen ( T. astrachanicus -morphotype) collected in Utlyukskij Liman, Ukraine ( UGSB 18130); O , P . Specimen of T. major collected in the Hrazdan River at the inflow of the Yerevan Reservoir, Armenia ( UGSB 20496); Q - T . Specimen of T. major from Zoeram, North Khorasan, Iran ( UGSB 21661); U , V . Specimen of T. schultzii collected in the Caspian Sea, offshore from Aktau, Kazakhstan ( UGSB 20714); W - Y . Lectotype of T. pallasi from Caspian Sea, Dagestan, Russia ( ZIN 54547/63); Za , Zb . Syntype of N. schultzii from the Caspian Sea ( ZIN , no. 5 in systematic catalogue). Specimens E-K and O-T used in the phylogeny (Fig. 2 ). Scale bars: 1 mm . Distribution. Theodoxus major is found in the Caspian Sea and parts of the Azov Sea ( Roth 1987 , Karpinsky 2002 ; Anistratenko et al. 2017 ; Sands et al. 2019a ) and is also present in the Volga and Don river systems ( Sands et al. 2019b ). It has likely become regionally extinct in the Aral Sea ( Andreev et al. 1992 ; Aladin et al. 1998 ; Plotnikov et al. 2016 ), although it may still persist in some of its associated drainages ( Zettler 2007 ). In Western Asia it can be found in the Aras River system ( Aliyev and Ahmadi 2010 ), Lake Yerevan and its catchment systems in Armenia ( Sands et al. 2019b ), and Masalli in Azerbaijan. Records of T. doriae Issel, 1865 [= T. pallidus ], T. euphraticus [= T. jordani ], or T. fluviatilis by Gloeer and Pesic (2012) and Mansoorian and Samaee (2012) from several mineral springs and streams in Gilan, Mazandaran, and the Khorasan provinces of northern Iran are likely misidentifications of T. major ( Sands et al. 2019b ; Fig. 3B ). Its presence in Lake Sevan (the supposed type locality) or the adjacent area around the lake was questioned by Akramovskiy (1976) (see above).