A revision of the extant species of Theodoxus (Gastropoda, Neritidae) in Asia, with the description of three new species Sands, Arthur F Gloeer, Peter Guerlek, Mustafa E Albrecht, Christian Neubauer, Thomas A Zoosystematics and Evolution 2020 96 1 25 66 5C791EBA-6982-5112-8C69-A9DDB8E00313 Sands & Glöer. Sands & Glöer & Gürlek & Albrecht & Neubauer 2020 Gastropoda Neritidae Theodoxus CoL Animalia Theodoxus wilkei Cycloneritida 0 25 Mollusca species wilkei sp. nov.   Typelocality.  Ciftelerspring, Cifteler, Eskisehir, Turkey; 39.34931°N, 31.05527°E(Figs 3D, 26A, B).   Figure 26. Typelocality of  Theodoxus wilkeiSands & Gloeersp. nov. A, B. Ciftelerspring, Cifteler, Eskisehir, Turkey, 39.34931°N, 31.05527°E.   Holotype.   RMNH. MOL.342208 ( Ciftelerspring, Cifteler, Eskisehir, Turkey; 39.34931°N, 31.05527°E) stored in NMNL: Shell height 6.9 mm, width 7.5 mm(Fig. 28A-D).   Paratypes.  Nineteen specimens from Ciftelerspring, Cifteler, Eskisehir, Turkey; 39.34931°N, 31.05527°E(Fig. 26A, B): 10 in NMNL( RMNH. MOL.342209-342211; Fig. 27E-J) and 9 in UGSB( UGSB20687, UGSB20741, UGSB20742; Fig. 28A-F).   Figure 27.  Theodoxus wilkeiSands & Gloeersp. 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 CiftelerSpring, Cifteler, Eskisehir, Turkey and stored in NMNL. Scale bars: 1 mm.   Figure 28.Radula of  Theodoxus wilkeiSands & Gloeersp. nov. paratypes( UGSB20687). 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).  Etymology. The species is named after the molluscan phylogeneticist and evolutionary biologist Thomas Wilke (Justus Liebig University Giessen, Germany).  Description. Shell (Fig. 27A-C, E-J): Hemispherical, transversely slightly elongate, consisting of typically three whorls that rapidly grow. Spire low, apex often corroded. Shell height ranges from 4.5-7.8 mm, width from 5.2-8.6 mm. Periostracum colour and patterning uniformly ivory or black, intermediate forms black with white-ivory speckles or stripes also exist; surface glossy or dull but always finely striated with growth lines. Aperture semicircular with no serrations on inner lip. Columellar plate is smooth, flat to slightly concave, inclined towards aperture; blue-grey in colour, some yellowing around edges. Operculum (Fig. 27D): Operculum plate made of two parts, calcareous base and conchioline lamella; operculum base bright yellow to deep orange, darkened orange-brown lamella. Left adductor on operculum base blunt and rounded. Strongly defined callus at top right edge of operculum base. Apophysis light to bright yellow. Apophysis broader at top, narrower at bottom (attenuated). Narrow rib-shield and small rib-pouch present on operculum; pseudo-apophysis lacking. Radula (Fig. 28A-F): R-central tooth flanked by A-central, B-central, C-central, E-lateral of each side. Additionally, two interconnected layers of marginal teeth encase central and lateral teeth. R-central varies in face shape; can be square face with slightly concave anterior edge or more triangular. A-central large and flat with strong attenuated ridge, broader at cusp. B-central diminished, forms irregular "S"shape. C-central equally diminished, partly hidden below lower edge of E-lateral. E-lateral is simple, semi-smooth to serrate on upper edge. First layer of marginal teeth comprises 37-40 teeth, which 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. The hemispherical, glossy black, black with white speckles or pure ivory, and finely striated shells of  T. wilkeisp. nov. are easily differentiable from  T. altenai, which displays light ivory checks on a dark brown-black background (Figs 4A-G, 27A-J), and  T. gloeri, which lacks shell pigmentation and bears strong axial ribs on the shell (Figs 11A-C, 27A-J). However, using only conchological features of periostracum colouration and patterning and shell shape, it is still challenging to differentiate  T. wilkeisp. nov. from some morphotypes of  T. anatolicus,  T. baeticus,  T. fluviatilis,  T. gurursp. nov.,  T. jordani,  T. macri,  T. major,  T. pallidus,  T. syriacus,  T. velox, and  T. wesselinghisp. nov., which can share similar shell shapes and colouration patterning (Figs 5A-M, 6A-G, M, 7M-P, 8A-D, 10E-H, 13A-G, 15P-R, 16C-P, 17A-E, 18A-G, 19O, P, 20A-D, I, J, 21A-D, I-R,  22I, J, 24E-J, 27A-D).  Theodoxus wilkeisp. nov. can be distinguished from Anatolian morphotypes of  T. baeticus, which typically displays ivory blotches on brown background (Fig. 7A-D);  T. jordani, which typically displays brown diagonal zig-zag line patterning on an ivory background (Fig. 15E-L); and  T. velox, which has white-ivory stripes on a dark background (Fig. 22K-M). Finally, the bright yellow to deep orange calcareous base of the operculum in  T. wilkeisp. nov. can help to distinguish it from  T. altenai,  T. anatolicus,  T. baeticus,  T. jordani,  T. macri,  T. major,  T. pallidus,  T. syriacus, and  T. wesselinghisp. nov., which typically have lighter calcareous bases ranging from ivory to cream (Figs 4- 8, 13, 15- 21, 24);  Theodoxus gurursp. nov., differs in having a light to dark brown operculum (Fig. 13, 27). There are a number of structural differences on the operculum. The attenuated apophysis in  T. wilkeisp. nov. allows a distinction from  T. altenaiand  T. jordani(Figs 4, 15, 17, 27). The presence of a rib-shield and rib-pouch further discriminate  T. wilkeisp. nov. from  T. altenai,  T. anatolicus,  T. jordani, and  T. macri, where these features are either absent or extremely diminished (Figs 4, 5, 15, 17, 18, 27). Furthermore, the rib-shield in  T. fluviatilisand  T. baeticusis typically broader than in  T. wilkeisp. nov. (Figs 6- 8, 9, 10, 27). Additionally, the lack of a pseudo-apophysis differentiates the new species from  T. altenai,  T. anatolicus,  T. baeticus,  T. gurursp. nov.,  T. jordani, and  T. macri(Figs 4- 8, 13, 15- 18, 27). Furthermore, the more rounded left adductor of the operculum base is only shared with  T. syriacusand  T. wesselinghisp. nov. (Figs 21, 24, 27). The strongly defined callus on the top right edge of the operculum base in  T. wilkeisp. nov. is only shared with  T. anatolicus,  T. fluviatilis,  T. major,  T. pallidus, and  T. wilkeisp. nov. and may be used to differentiate this species from all others (Fig. 27D). Concerning the radula,  T. wilkeisp. nov. can be distinguished from  T. gurursp. nov. by a square to triangulate R-central face (Figs 14B, 28B). The serrations on the upper edge of the E-lateral distinguish this species from  T. wesselinghisp. nov.,  T. fluviatilis, and  T. gurursp. nov., which have smooth, blade-like edges (Figs 14B, C, 27C, 28B-D; also see Zettler 2008).  Remarks.   Theodoxus wilkeisp. nov. forms a part of a larger clade that includes  T. syriacusand  T. wesselinghisp. nov., where it shares a closer sister-species relationship with  T. wesselinghisp. nov. ( Sands et al. 2019a; Fig. 2). The three species likely diverged from one another within a short time around the Pliocene-Pleistocene transition (Fig. 2).  Distribution. Only known from the typelocality (Figs 3D, 26A, B).  Ecology.   Theodoxus wilkeisp. nov. appears endemic to a freshwater spring environment with clear water (Fig. 26A, B). This spring environment is characterised by macrophytes in the littoral zone and a floor of small and large stones, rocks and course-grained sand (Fig. 26A, B).  Theodoxus wilkeisp. nov. is particularly numerous on larger stones and rocks and co-occurs with  Pseudamnicolaand  Melanopsis(personal observation M.E.G.). RMNH Turkey 39.34931 31.05527 A Turkey 39.34931 31.05527