Theodoxus pallidus (Dunker, 1861)

Sands, Arthur F, Gloeer, Peter, Guerlek, Mustafa E, Albrecht, Christian & Neubauer, Thomas A, 2020, A revision of the extant species of Theodoxus (Gastropoda, Neritidae) in Asia, with the description of three new species, Zoosystematics and Evolution 96 (1), pp. 25-66 : 25

Theodoxus pallidus (Dunker, 1861) Figure 20A-Y

Neritina pallida Dunker 1861: 40; Martens 1879: 239, pl. 23, figs 11, 12; Kobelt 1899: 13, pl. 214, fig. 1349.

Theodoxus Doriae Issel 1865: 23-24; Issel 1866: 407-408; Biggs 1937: 349; Mansoorian and Samaee 2012: 55-56 (partim, only material from Chaharmahal and Bakhtiari, Isfahan, and Yazd provinces).

Neritina Doriae : Martens 1879: 222-223, pl. 21, figs 22, 23; Kobelt 1899: 7-8, pl. 212, fig. 1335.

Theodoxus doriae var. obscura Biggs 1937: 349.

Theodoxus pallidus : Starmühlner and Edlauer 1957: 437-442, text figs 1-5, fig. 1a (synonymy tentative); Roth 1987: 75; Sands et al. 2019b: 3, fig. 1.

? Theodoxus (Theodoxus) doriae : Schütt and Şeşen 1989b: 41.

? Theodoxus euphraticus : Mansoorian and Samaee 2012: 56-59 (partim, only material from Kerman and Yazd provinces; non Neritina euphratica Mousson, 1874 [= T. jordani ])

Theodoxus fluviatilis : Glöer and Pešić 2012: 16-17 (partim, only Fars and Hormozgan material; non Nerita fluviatilis Linnaeus, 1758).

Theodoxus pallida [sic]: Glöer and Pešić 2012: 17-18, fig. 3a-c.

Type locality.

Southern Persia (= Iran).

Type material.

Two syntypes of N. pallida are deposited in ZMB (coll. no. ZMB /Moll 108792-108793) . Nine syntypes of N. doriae are stored in MSNG (without coll. no.) . The holotype of T. doriae var. obscura from Aqda, Iran, is stored in BMNH (coll. no. 1958.6.13.22) .

Remarks.

Theodoxus pallidus was described by Dunker (1861) from southern Persia (present-day Iran). Starmühlner and Edlauer (1957) synonymised T. pallidus and T. doriae based on similarities among the material and distinguished this species from T. fluviatilis by a higher spire (Figs 9 , 10 , 20 ). Glöer and Pešić (2012) recently reviewed the material of T. pallidus from Starmühlner and Edlauer (1957) and corroborated the differentiation from T. fluviatilis and provided more differentiating features based on the operculum. However, Glöer and Pešić (2012) differed in the synonymy of T. doriae , which they synonymised with T. fluviatilis . Molecular data of material from southern Iran conforming to Dunker’s (1861) description of T. pallidus and material of T. doriae from Kerman province support the independence of T. pallidus from T. fluviatilis , as well as the synonymy of T. pallidus and T. doriae as suggested by Starmühlner and Edlauer (1957) ( Sands et al. 2019b). In turn, T. pallidus shares a close sister-species relationship with T. major ( Sands et al. 2019b; Fig. 2 ). The pronouncement of the spire seems to vary among populations in T. pallidus and the shell shape may largely mimic those seen in T. major (except T. schultzii -morphotype). However, this species seems to be dominated by black morphs or specimens with thicker dark banding, and the conchioline lamella is much more reduced in comparison to the sister species (Figs 19 , 20 ).

Theodoxus doriae var. obscura Biggs, 1937 ranges within the variability shown by the syntype series of T. doriae (Fig. 20Q-Y ) concerning shell shape and colouration and is consequently considered a junior synonym of T. pallidus .

Distribution.

All records of T. pallidus are restricted to south-central Persia and occur from the Zagros Mountains eastward in at least Chaharmahal and Bakhtiari, Fars, Hormozgan, Isfahan, Kerman, and Yazd provinces of Iran ( Starmühlner and Edlauer 1957; Mansoorian and Samaee 2012; Sands et al. 2019b; Fig. 3B ). Records of T. doriae [= T. pallidus ] from Gilan and Mazandaran provinces by Mansoorian and Samaee (2012) and North Khorasan and Razavi Khorasan provinces by Glöer and Pešić (2012) are likely misidentified T. major ( Sands et al. 2019b; Fig. 3B ), and those from Anatolia ( Roth 1987) are likely misidentified T. fluviatilis ( Sands et al. 2019a).

Figures

Figure 2. Dated phylogeny of the genus Theodoxus constructed with BEAST, based on existing GenBank and newly incorporated data for COI, 16 S and ATPα (Suppl. material 1: Table S 1). Morphospecies where associations are queried are highlighted by a question mark after the species name (see the " Systematic checklist " for more information). Small green (PP ≥ 0.95) and red (PP <0.95) dots on nodes indicate the relative posterior probability support of divergence events. Node labels (1 - 32) correspond to divergence dates and HPD intervals in millions of years ago (Mya) for selected nodes (see Suppl. material 1: Table S 3). Dashed dark blue and light blue lines represent the minimum interspecific and maximum intraspecific variation determined by Sands et al. (2019 a) to aid Theodoxus spp. delimitation (see see Methods, Phylogenetics and species delimitation and that study for more information on the delimitation methods).

Figure 3. Occurrence map for Theodoxus spp. in Asia. All points conform to specimens used in the phylogenetic analyses (Suppl. material 1: Table S 1), except for T. gloeri for which no molecular data are available and only the type and paratype localities are indicated. Species are partitioned across four identical maps (A - D) to limit overlap of points as far as possible. Barring T. gloeri, closer related species are grouped together (Fig. 2).

Figure 9. Theodoxus fluviatilis (Linnaeus, 1758). A - D. Specimen collected close to Oued Laabid, Morocco (UGSB 18106) (Fig. 2); E - H. Specimen from the Danube River, Woerth an der Donau, Germany (UGSB 24173); I - L. Specimen (T. euxinus - morphotype) collected in the Papuc Creek, Kiyikoey, Turkey (UGSB 24172) (Fig. 2); M - P. Specimen (T. euxinus - morphotype) from Ovidiopol, Ukraine (UGSB 18124); Q - S. Specimen (T. heldreichi - morphotype) collected in Lake Egirdir, Turkey (UGSB 20361); T, U. Specimen (T. danasteri - morphotype) collected in Krasna Kosa, Ukraine (UGSB 18417) (Fig. 2); V. Opercula of a T. danasteri - morphotype from Lake Skadar, Montenegro (UGSB 24171). Specimens A-D, I-L and T-U were used in the phylogeny (Fig. 2). Scale bars: 1 mm.

Figure 10. Theodoxus fluviatilis (Linnaeus, 1758). A - D. Specimen (conforming to T. sarmaticus) from the Dnieper-Bug estuary, Ukraine (UGSB 18328); E - H. Specimen (T. subthermalis - morphotype) from Novy Afon, Abkhazia, Georgia (UGSB 18402); I - K. Syntype of N. saulcyi from near the Penteli Monastery, Greece (MHNG-MOLL- 111736); L. Specimen (T. saulcyi - morphotype) from Stilos, Crete, Greece (UGSB 20519) incorporated into the phylogeny (Fig. 2). Scale bars: 1 mm.

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.

Figure 20. Theodoxus pallidus (Dunker, 1861). A - D. Specimen from Haji Abad, Fars, Iran (UGSB 22227); E - H. Syntype of N. pallida from southern Iran (ZMB 108.792); I, J; K, L. Two syntypes of N. pallida from southern Iran (ZMB 108.793); M - P. Specimen (T. doriae - morphotype) from a spring near Harat, Yazd, Iran (UGSB 21706); Q, R; S, T; U, V; W - Y. Four syntypes of N. doriae from the thermal springs of Kerman, Iran (MSNG, without coll. no.). Specimens A-D and M-P were used in the phylogeny. Scale bars: 1 mm.