Pseudocleopatra voltana Mandahl-Barth, 1973

Neiber, Marco T., Kahl, Sandra M., Wiggering, Benedikt & Glaubrecht, Matthias, 2019, Adding the West-African riverine component: Revision of the Recent freshwater snails belonging to Pseudocleopatra Thiele, 1928 (Caenogastropoda, Cerithioidea, Paludomidae), Zootaxa 4674 (3), pp. 301-328 : 312-314

Pseudocleopatra voltana Mandahl-Barth, 1973

Figs 8B , 11–14

Pseudocleopatra togoensis Thiele, 1928: 394 (in part); Brown (1980: 111, fig. 63e).

Pseudocleopatra voltana Mandahl-Barth, 1973: 279–281 , fig. 3a, h; Brown (1980: 111–112); Brown & Kristensen (1993: 28, 51); Brown (1994: 128–129, 537, 580, fig. 61f); Glaubrecht (1996: 144–145, 147–148, fig. 24b, c); Kristensen & Stensgaard (2010a: e.T165376A6007457).

Type locality. “ River Volta at Daboya ” ; Ghana, Northern Region, West Gonja District, Daboya, White Volta, 9°32’06’’ N, 1°22’48’’ W .

Type material. Holotype, DBL 2594-1 and two paratypes, DBL 2594 - 2,3 , leg. F.S. McCullough . On the original label all three specimens are indicated as “Type”. From the original description it is clear, however, that the specimen depicted here in Fig. 11A is the holotype originally selected by Mandahl-Barth (1973: 281) . Additional paratypes: All from Ghana: “Mogeyenga village, NE-Region” (not localised), DBL 2591 , 7 specimens; “Apaso village” (= Volta Region, Krachi East District, Apase, 7°31’33.6”, 0°07’04.8” E, today inundated by Lake Volta), DBL 2592 , 3 specimens ; “Northeast region” (= Northeastern Ghana, without exact locality), DBL 2593 , 1 specimen ; “White Volta at Daboya” (= Northern Region, West Gonja District , Daboya , White Volta, 9°32’06” N, 1°22’48” W), MRAC 799144 , 2 specimens ; “Fluss Volta bei Apaso ( Togo)” ( Volta River near Apaso ( Togo) = Volta Region , Krachi East District , Apase , 7°31’33.6”, 0°07’04.8” E, today inundated by Lake Volta ).

Other material examined. “Fluss Volta bei Apaso ( Togo)” (River Volta near Apaso ( Togo) = Ghana, Volta Region, Krachi East District , Apase , 7°31’33.6”, 0°07’04.8” E, today inundated by Lake Volta), ZMB 190049 , 1 specimen. Note that this specimen is a former syntype of P. togoensis Thiele, 1928 .

Shell ( Fig. 11 ). The shell of P. voltana is reddish to dark brown or yellowish-ochre, sometimes with darker bands or a darker area near the columella, and has an ovate to elongate shape, with up to seven whorls and a pointed apex (if not eroded). The whorls are convex to almost flat, with 1–6 distinct spiral cords; in few specimens these ridges are only weakly developed. The aperture is holostome and ovate, higher than wide and slightly drawn out at the upper angle; outer margin sinuous in lateral view, columella slightly curved to almost straight and the basal margin evenly rounded (in the most mature specimens slightly produced). Umbilicus slit-like or closed.

Measurements (n = 16). h: 8.52 ± 1.53 mm (range: 6.0–12.0 mm); w: 4.83 ± 0.60 mm (range: 3.7–5.8 mm); bw: 6.83 ± 0.89 mm (range: 4.8–8.3 mm); la: 4.11 ± 0.43 mm (range: 3.2–4.8 mm); wa: 2.72 ± 0.27 mm (range: 2.2–3.2 mm).

Ratios (n = 16). h/w: 1.75 ± 0.16 (range: 1.51–2.17); h/la: 2.06 ± 0.20 (range: 1.86–2.60).

Operculum ( Fig. 8B ). The operculum is corneous, with a paucispiral, rather large nucleus that can reach up to ⅓ of the maximum diameter and possesses a concentric margin.

Radula ( Figs 12–13 , Table 2 ). Due to the lack of alcohol material, already prepared radula slides from the collection of the DBL were examined. Two slides of specimens from two different localities were examined (DBL 2592 and DBL 2594). The rachidian tooth is of squarish shape, with a straight to slightly V-shaped upper edge. The number of denticles is variable, with a prominent mesocone and 4–5 flanking denticles on either side, or mesocone not prominent, i.e. about the same size as the flanking denticles. The lateral teeth have relatively short but straight lateral extensions. The cutting edge bears 12–15 small denticles hardly differing in size and lacking a prominent mesocone. Inner and outer marginal teeth subequal in size and slightly curved. Both, the inner and outer marginal teeth bear 10–12 denticles each that are of approximately the same size.

Distribution ( Fig. 14 ). Pseudocleopatra voltana is known from the southern part of present day Lake Volta and several localities along the White Volta River.

Remarks. Pseudocleopatra voltana has a more elongate shell than the remaining three Pseudocleopatra species. When the spiral sculpture is well-developed, the species is very distinctive and cannot be confused with any of its congeners. Only in few specimens the spiral sculpture was weak on the last whorl. Nothing is known about the ecology of the species and new records do not exist.

Figures

FIGURE 8. Opercula of Pseudocleopatra Thiele, 1928 species. A. Lectotype of P. togoensis Thiele, 1928, ZMB 190048b. B. Paratype of Pseudocleopatra voltana Mandahl-Barth, 1973, Mogeyenga village, DBL 2591. C. Probable paratype of Pseudocleopatra dartevellei Mandahl-Barth, 1973, Matadi, DBL 2583. D. Pseudocleopatra broecki (Putzeys, 1899) n. comb., MCZ 171520. E. Lectotype of Pseudocleopatra broecki (Putzeys, 1899) n. comb., MRAC 47360. Scale bar: 1mm.

FIGURE 11. Shells of Pseudocleopatra voltana Mandahl-Barth, 1973. A. Holotype, DBL 2594-1. B. Paratype, from the type locality; DBL 2594-2. C. Paratype, from the type locality, DBL 2594-3. D. Paratype, Ghana, NE region, without exact locality, DBL 2593. E. Paratype, Mogeyenga village, DBL 2591. F. Paralectotype of Pseudocleopatra togoensis Thiele, 1928, ZMB 190049. Scale bar: 5 mm.

FIGURE 12. Radula of Pseudocleopatra voltana Mandahl-Barth, 1973, paratype, Apaso village, DBL 2592. A. Radula ribbon, scale bar: 25 μm. B. Lateral and central teeth; scale bar: 5 μm. C. Cutting edge of lateral and central teeth; scale bar: 3 μm. D. Central, lateral and marginal teeth; scale bar: 5 μm.

FIGURE 13. Radula of Pseudocleopatra voltana Mandahl-Barth, 1973, paratype, Daboya, DBL 2594. A. Radula ribbon, scale bar: 25 μm. B. Lateral and central teeth; scale bar: 20 μm. C. Cutting edge of lateral and central teeth; scale bar: 6 μm. D. Central, lateral and marginal teeth; scale bar: 8 μm.

FIGURE 14. Known occurrence records of Pseudocleopatra voltana Mandahl-Barth, 1973 in the Volta River system. The asterisk indicates the type locality; open symbols indicate samples of dry material. The arrow indicates the approximate location of the Akosombo dam.