Theodoxus wesselinghi Sands & Gloeer, 2020

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 wesselinghi Sands & Gloeer sp. nov. Figures 23A-H , 24A-M , 25A-F

Theodoxus fluviatilis : Odabaşı and Arslan 2015: 330-331 (non Nerita fluviatilis Linnaeus, 1758).

Theodoxus anatolicus : Yıldırım et al. 2018: 118 (non Nerita anatolica Récluz, 1841).

Type locality.

Sakarya River, Çayköy, Bilecik, Turkey; 40.0439°N, 30.452°E (Figs 3D , 23A, B ).

Holotype. RMNH. MOL.342200 (Sakarya River, Çayköy, Bilecik, Turkey; 40.0439°N, 30.452°E) stored in NMNL: Shell height 6.0 mm, width 6.0 mm (Fig. 24A-D ) .

Paratypes. Twenty-four specimens from Sakarya River, Çayköy, Bilecik, Turkey; 40.0439°N, 30.452°E (Fig. 23A, B ): 11 in NMNL ( RMNH. MOL.342201, RMNH. MOL.342202; Fig. 24E-G ) and 13 in UGSB ( UGSB 20688, UGSB 20743, UGSB 20744; Fig. 25A, B, D ) . Twenty-four specimens from an unnamed roadside spring in Fele, İsparta province, Turkey; 38.00358°N, 31.47217°E (Fig. 23C, D ): 11 in NMNL ( RMNH. MOL.342203, RMNH. MOL.342204; Fig. 24H-J ) and 13 in UGSB ( UGSB 20684, UGSB 20735, UGSB 20736) . Twenty-five specimens from Eflatun Pınarı, near Sadıkhacı, Konya, Turkey; 37.8256°N, 31.6748°E (Fig. 23E, F ): 11 in NMNL ( RMNH. MOL.342205, RMNH. MOL.342206; Fig. 24K-M ) and 14 in UGSB ( UGSB 20685, UGSB 20737, UGSB 20738; Fig. 25F ) . Thirty specimens from Balıkdamı Wetland spring, Eskişehir, Turkey; 39.15277°N, 31.61562°E (Fig. 23G, H ): 13 in NMNL ( RMNH. MOL.342207) and 17 in UGSB ( UGSB 20686, UGSB 20739, UGSB 20740; Fig. 25C, E ) .

Etymology.

The species is named in honour of the molluscan palaeontologist Frank P. Wesselingh (Naturalis Biodiversity Center, Leiden, The Netherlands) for his contributions to malacology.

Description.

Shell (Fig. 24A-C, E, F, H-M ): Hemispherical, transversely elongate, consisting of typically three whorls that rapidly grow. Spire well defined, moderate height for Theodoxus ; often corroded along with other parts of shell. Shell height ranges from 4.0- 6.8 mm, width from 3.8-7.1 mm. Juveniles appear more globular. Periostracum is uniformly ivory or solid black, intermediate forms with broad brown-black smudged diagonal stripes also exist; surface glossy, finely striated with growth lines. Aperture semicircular, no serrations on inner lip. Columellar plate smooth, flat to slightly concave, inclined towards aperture; colouration blue-grey in darker shelled individuals to white in lighter forms.

Operculum (Fig. 24D, G ): Operculum plate made of two parts, calcareous base and conchioline lamella; operculum base light, mostly ivory to white, white lamella with distinct orange edge on border with operculum base. Operculum base left adductor can be blunt and rounded, weak callus on top right edge. Apophysis follows same colour scheme as operculum calcareous base, broader at top and narrower and attenuated at bottom. Very narrow rib-shield, deep rib-pouch present on operculum. Operculum lacks a pseudo-apophysis.

Radula (Fig. 25A-F ): R-central tooth flanked by A-central, B-central, C-central, E-lateral on each side. Additionally, two interconnected layers of marginal teeth encase central and lateral teeth. R-central shows some variation among populations, slightly spherical or more squared face with slightly concave anterior edge. A-central large and flat with thin ridge that becomes broad and folded right at end of cusp. B-central diminished, forms irregular “S” shape. C-central equally diminished, hidden below lower edge of E-lateral. E-lateral simple with smooth upper edge. First layer of marginal teeth consists of 37-44 teeth that decrease in size away from E-lateral but increase in size and bear serrations on edges of small faces; semidetached from second layer, which is fused and forms outer wall.

Differentiating features.

Based on conchological features of periostracum colouration and patterning and shell shape, it is difficult to differentiate T. wesselinghi sp. nov. from most Asian Theodoxus spp. given the variety in colour and patterns among the type material (Fig. 24A-M ). However, in some instances it can be distinguished from Anatolian morphotypes of T. baeticus , which typically displays ivory blotches on a brown background (Fig. 7A-D ); T. altenai with clear ivory checks on a dark brown-black background (Fig. 4A-G ) and T. gloeri lacking shell pigmentation and bearing strong axial ribs on the shell (Fig. 11A-C ). The light ivory-coloured operculum calcareous base makes this species distinct from T. gurur sp. nov. (light to dark brown; Figs 13D , 24D, G ) and T. wilkei sp. nov. (bright orange; Figs 24D, G , 27D ).

More differentiating features occur in the operculum structure (Fig. 24D, G ). The presence of an attenuated apophysis distinguishes T. wesselinghi sp. nov. from T. altenai and T. jordani , which have non-attenuated apophyses (Figs 4 , 15 , 17 ). A rib-pouch and rib-shield are either totally lacking or extremely diminished in T. altenai , T. anatolicus , T. jordani , and T. macri (Figs 4 , 5 , 15 , 17 , 18 ), while they are more pronounced in T. wesselinghi sp. nov. (Fig. 24 ). The rib-shield in T. wesselinghi sp. nov. is however less broad than that typically observed in T. fluviatilis and T. baeticus (Figs 6 - 10 ). Furthermore, the lack of a pseudo-apophysis differentiates the new species from T. altenai , T. anatolicus , T. baeticus , T. gurur sp. nov., T. jordani , and T. macri (Figs 4 - 8 , 13 , 15 , 17 , 18 ). Additionally, the presence of a weak callus on the top right edge of the operculum base in T. wesselinghi sp. nov. helps to differentiate this species from T. gurur sp. nov. and T. jordani , which lack a callus (Figs 13 , 15 , 17 , 18 , 24 ), as well as from T. anatolicus , T. fluviatilis , T. major , T. pallidus , and T. wilkei sp. nov., which have stronger calluses (Figs 5 , 9 , 10 , 19 , 20 , 24 , 27 ).

Based on the available data for Theodoxus ralulae, T. wesselinghi sp. nov. can be distinguished by a more globular R-central face from T. gurur sp. nov., T. wilkei sp. nov., T. fluviatilis , and T. jordani , where it is more rectangular or triangulate (see Baker 1923; Zettler 2008; Figs 14B , 25B , 28B ). Furthermore, the smooth upper edge of the E-lateral can be used to distinguish this species from T. wilkei sp. nov. and T. major , which generally have E-laterals with serrated edges (see Anistratenko et al. 2017; Figs 25C , 28C, D ).

Remarks.

Theodoxus wesselinghi sp. nov. forms part of a larger clade that includes T. syriacus and T. wilkei sp. nov., where it shares a closer sister-species relationship with T. wilkei sp. nov. ( Sands et al. 2019a; Fig. 2 ). The three species likely diverged from one another in quick succession over the Pliocene-Pleistocene transition (Fig. 2 ).

Distribution.

Known so far only from the four localities in central-west Anatolia (Figs 3D , 23A-H ).

Ecology.

Theodoxus wesselinghi sp. nov. can be found in both springs ( Balıkdamı Wetland, Eflatun Pınarı, Fele; Fig. 23C-H ) and streams (Sakarya River, Çayköy; Fig. 23A, B ) with clear water. The occurrence of macrophytes appears negligible to the species as it occurs in localities both with (Fig. 23E-H ) and without (Fig. 23A-D ) aquatic plant growth. The floors of all localities are made up of coarse grained sand and large and small rocks and stones that T. wesselinghi sp. nov. is often attached to (personal observation M.E.G.; Fig. 23H ). Theodoxus wesselinghi sp. nov. co-occurs with Potamopyrgus antipodarum (Gray, 1843) and Isparta felei Yıldırım, Koca, Gürlek & Glöer, 2018 in Fele spring, Falsipyrgula sp. in Eflatun Pınarı, and Pseudamnicola natolica ( Küster, 1852) (and possibly also T. gloeri ; Odabaşı and Arslan 2015) in the Balıkdamı Wetland spring (personal observation M.E.G.).

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 4. Theodoxus altenai Schuett, 1965. A - C. Holotype from Lake Kirkgoez, Doesemealti, Antalya, Turkey (RNL V. 56 / 1, NMNL). D - G. Topotype (UGSB 24167) incorporated into the phylogeny (Fig. 2). Scale bars: 1 mm.

Figure 5. Theodoxus anatolicus (Recluz, 1841). A - D. Specimen collected at Isikli, Denizli, Turkey (UGSB 24168) incorporated into the phylogeny (Fig. 2); E - G. Lectotype of N. anatolica from Izmir, Turkey (MHNG-MOLL- 15028). H, I. Paralectotype of N. anatolica from Izmir, Turkey (MHNG-MOLL- 15028); J, K. Paralectotype of N. anatolica from Chios, Greece (MNHN-IM- 2000 - 32519); L, M. Syntype of N. belladonna from Izmir, Turkey (ZMZ 528908). Scale bars: 1 mm.

Figure 6. Theodoxus baeticus (Lamarck, 1822). A - C. Paralectotype of N. baetica from Andalusia, Spain (MHNG-MOLL- 51319). D) Operculum of a paralectotype of N. baetica from Andalusia (MHNG-MOLL- 51319); E - G. Lectotype of N. baetica from Andalusia (MHNG-MOLL- 51319); H-J; K; L; M; N. Five syntypes of N. meridionalis from Sicily (ZMB, without coll. no.); O - R. Topotype of N. guadianensis collected in the Guadiana River near Mertola, Portugal incorporated into the phylogeny (UGSB 22084); S - V. Specimen from Soller, Balearic Islands used in the phylogeny (UGSB 19162). Scale bars: 1 mm.

Figure 7. Theodoxus baeticus (Lamarck, 1822). A - D. Specimen (T. callosus - morphoype) collected in Akyaka, Turkey (UGSB 19118); E - H. Specimen (T. callosus - morphotype) collected in Kato Tragana, Greece (UGSB 2488); I - L. Specimen (T. varius - morphotype) collected at the Blue Eye Nature Monument, Albania (UGSB 24170); M - P. Specimen (T. meridionalis - morphotype) collected at the Ketana Oasis, Gabes, Tunisia (UGSB 18111). All specimens, except A-H, were used in the phylogeny (Fig. 2). Scale bars: 1 mm.

Figure 8. Theodoxus baeticus (Lamarck, 1822). A - D. Specimen from Cuquillo, Granada, Andalusia, Spain (UGSB 22089); E - H. Specimen (T. meridionalis - morphotype) collected in the Palancia River, Navajas, Spain (UGSB 22090); I - L. Specimen (T. elongatulus - morphotype) from Arrancada, Pombal, Portugal (UGSB 22080); M - P. Specimen (T. velascoi - morphotype) from Montanejos, Castellon, Spain (UGSB 22082). Theodoxus cf. valentinus (Graells, 1846). Q - S. Specimen conforming to T. valentinus from the Verd River, Masalaves, Spain (UGSB 21787); T. Operculum of a specimen conforming to T. valentinus from the same locality as Q-S (UGSB 22087). All specimens, except Q-S, were used in the phylogeny (Fig. 2). Scale bars: 1 mm.

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 11. Theodoxus gloeri Odabasi & Arslan, 2015. A - C. Paratype from Balikdami Wetland-Sakarya River, Eskisehir, Turkey (coll. Gloeer). Scale bar: 1 mm.

Figure 13. Theodoxus gurur Sands & Gloeer sp. nov. A - D. Holotype from the Suyunbasi spring complex, Ayrancilar, Izmir, Turkey stored in NMNL (RMNH. MOL. 342197); E - G. Paratype from same locality and storage facility (RMNH. MOL. 342199). Scale bars: 1 mm.

Figure 14. Radula of Theodoxus gurur Sands & Gloeer sp. nov. paratypes (UGSB 20689). A. Portion of the radula showing full sets of teeth; B. Magnified view of the central and lateral teeth; C. Magnified view of the lateral and marginal teeth; D. Magnified view of the first row of marginal teeth; E. Merging point between the first and second rows of marginal teeth; F. Magnified view of the faces of inner marginal teeth belonging to the first row. Scale bars: 100 μm (A-D), 20 μm (E-F).

Figure 15. Theodoxus jordani (G. B. Sowerby I, 1836). A - D. Specimen from the Avakas Gorge, Peyia, Cyprus (UGSB 18321) incorporated into the phylogeny (Fig. 2); E - H. Specimen collected in the Ceyhan River, Eski Misis, Adana, Turkey (UGSB 20777); I - L. Specimen from the Orontes River, Antakya, Hatay, Turkey (UGSB 24175) used in the phylogeny (Fig. 2); M - O. Specimen (T. euphraticus - morphotype) from the Seyed Hosein Park spring, near the Bishapur, Fars, Iran (UGSB 22233); P - R. Topotype of N. jordani from the River Jordan, Israel (UGSB 24177) incorporated into the phylogeny (Fig. 2); S, T. Specimen (T. euphraticus - morphotype) from the Karun River, Ahvaz, Iran (UGSB 21681); U. Specimen (T. niloticus - morphotype) collected in the Nile River, Egypt (UGSB 24178) used in the phylogeny (Fig. 2); V. Specimen (T. euphraticus - morphotype) from the Karun River, Ahvaz, Iran (UGSB 21682). Scale bars: 1 mm.

Figure 17. Theodoxus jordani (G. B. Sowerby I, 1836). A - C. Syntype of N. meridionalis var. mesopotamica from near Diyarbakir, Turkey (ZMZ 528914); D, E. Specimen (T. mesopotamicus - morphotype) collected in Sanliurfa, Turkey (UGSB 23426) and used in the phylogeny (Fig. 2); F - H; K - M. Two syntypes of N. cinctella collected at the source of River Chabur near Ras al-Ayn, Syria (ZMB / Moll 21732); I, J. Topotype of N. cinctella from the same locality (UGSB 18762). Scale bars: 1 mm.

Figure 18. Theodoxus macri (G. B. Sowerby II, 1849). A - D. Specimen collected close to Harbiye Falls, Harbiye, Antakya, Turkey (UGSB 24179); E - H. Specimen from Lake Yenisehir, Reyhanli, Turkey (UGSB 24180); I, J. Specimen from Lake Balik, Adalar, Turkey (UGSB 24181). All specimens (A-J) were used in 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.

Figure 23. Type locality of Theodoxus wesselinghi Sands & Gloeer sp. nov. A, B. Sakarya River, Caykoey, Bilecik, Turkey, 40.0439 ° N, 30.452 ° E. Further paratype localities: C, D. Unnamed roadside spring in Fele, Isparta province, Turkey, 38.00358 ° N, 31.47217 ° E; E, F. Eflatun Pinari, near Sadikhaci, Konya, Turkey, 37.8256 ° N, 31.6748 ° E; G, H. Balikdami Wetland spring, Eskisehir, Turkey, 39.15277 ° N, 31.61562 ° E.

Figure 24. Theodoxus wesselinghi Sands & Gloeer sp. nov. A - D. Holotype collected in the Sakarya River, Caykoey, Bilecik, Turkey (RMNH. MOL. 342200); E - G. Paratype from the same location as the holotype (RMNH. MOL. 342202); H - J. Paratype from Fele, Isparta province, Turkey (RMNH. MOL. 342204); K - M. Paratype from Eflatun Pinari, Konya province, Turkey (RMNH. MOL. 342206). All photographed material (A-M) is stored in NMNL. Scale bars: 1 mm.

Figure 25. Radula of Theodoxus wesselinghi Sands & Gloeer sp. nov. paratypes. A. Portion of the radula showing full sets of teeth (UGSB 20688); B. Magnified view of the central teeth (UGSB 20688); C. Magnified view of the lateral and marginal teeth (UGSB 20686); D. Magnified view of the first and second rows of marginal teeth (UGSB 20688); E. Magnified view of the first row of marginal teeth (UGSB 20686); F. Magnified view of the faces of inner marginal teeth belonging to the first row (UGSB 20685). Scale bars: 100 μm (A-E), 20 μm (F).

Figure 27. Theodoxus wilkei Sands & Gloeer sp. nov. A - D. Holotype (RMNH. MOL. 342208); E - G. Paratype (RMNH. MOL. 342210); H - J. Paratype (RMNH. MOL. 342211). All photographed material is from the Cifteler Spring, Cifteler, Eskisehir, Turkey and stored in NMNL. Scale bars: 1 mm.

Figure 28. Radula of Theodoxus wilkei Sands & Gloeer sp. nov. paratypes (UGSB 20687). A. Portion of the radula showing full sets of teeth; B. Magnified view of the central and lateral teeth; C. Magnified view of the lateral and first and second rows of marginal teeth; D. Magnified view of the lateral teeth; E. The first row of marginal teeth; F. Magnified view of the faces of inner marginal teeth belonging to the first row. Scale bars: 100 μm (A-D), 20 μm (E-F).