Pseudocleopatra dartevellei 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 : 315-320

Pseudocleopatra dartevellei Mandahl-Barth, 1973

Figs 8C , 15–18

Pseudocleopatra dartevellei Mandahl-Barth, 1973: 280–281 , fig. 3d–f, i; Mandahl-Barth (1974: 355); Brown (1980: 112–113, fig. 64a); Danish Bilharziasis Laboratory (1982: 25, 50, fig. 77); Brown (1994: 129–130, 539, 570, fig. 62a); Glaubrecht (1996: 27, 144, 146–148, 307–308, 493, fig. 25, pl. 2, fig. 5, pl. 21, figs 3–4); Van Damme & Pickford (2003: 3, fig. 1g); Jørgensen (2010b: e.T184587A8297083); Graf et al. (2011: 51, 53).

Type locality. “ River Congo at Matadi ” ; Democratic Republic of the Congo, Kongo Central Province , Congo River at Matadi, ca. 5°49’15” S, 13°27’00” E .

Type material. Holotype, MRAC 799161 , leg. E. Dartevelle. Probable paratypes (not explicitly mentioned in the original description): all from the Democratic Republic of the Congo, Kongo Central Province : “Île des Princes” (= Île des Princes , ca. 5°53’00” S, 13°06’00” E), MRAC 146342 , MRAC 146371 ,> 25 specimens ; “Chaudron d’Enfer prés Matadi” (= Chaudron d’Enfer near Matadi , 5°49’48” S, 13°25’54” E), MRAC 106951 ,> 25 specimens ; “Matadi” (= Congo River at Matadi , ca. 5°49’15” S, 13°27’00” E), DBL 2583 , 3 specimens ; “ Congo: Matadi” (= Congo River at Matadi , ca. 5°49’15” S, 13°27’00” E), MRAC 107737 , 5 specimens ; “Matadi, ilot” (= Congo River at Matadi, small island, ca. 5°49’15” S, 13°27’00” E), MRAC 260702, 13 specimens ; “Île Selonga” (= Île Selonga, 5°52’52” S, 13°01’45” E), MRAC 146372 , MRAC 146426 , 9 specimens.

Shell ( Fig. 15 ). The shell of P. dartevellei is yellowish brown to olive and has an ovate to conical shape, with up to six whorls (usually with eroded spire, then only about three whorls remaining). The whorls are rather convex, with very fine growth lines crossed by indistinct spiral lines. The aperture is holostome and ovate, higher than wide and slightly drawn out at the upper angle; outer margin sinuous in lateral view, columella curved and the basal margin evenly rounded (somewhat produced in the most mature specimens). Umbilicus closed.

Measurements (n = 80). h: 4.21 ± 1.67 mm (range: 1.7–9.6 mm); w: 3.22 ± 1.16 mm (range: 1.4–6.8 mm); bw: 3.66 ± 1.44 mm (range: 1.1–8.3 mm); la: 2.42 ± 1.04 mm (range: 0.9–5.8 mm); wa: 1.79 ± 0.68 mm (range: 0.8–3.9 mm).

Ratios (n = 80). h/w: 1.30 ± 0.09 (range: 1.11–1.62); h/la: 1.77 ± 0.15 (range: 1.48–2.20).

Operculum ( Fig. 8C ). The operculum is corneous, with a paucispiral, rather large nucleus that can reach up to ⅔ of the maximum diameter and possesses a concentric margin.

Radula ( Figs 16–17 , Table 2 ). Two distinct radula types were found referred to as “Morph a” ( Fig. 16 ) and “Morph b” ( Fig. 17 ). Morph a represents a typical paludomid radula. The rachidian tooth is squarish, with a straight upper edge. The cutting edge tapers to a distinct V-shaped tip and bears 5–6/1/6–8 denticles. The mesocone is very prominent and triangular in shape. It is about twice as long as wide and also wider than the lateral denticles, which decrease in size towards the margin of the tooth. The lateral teeth have very short and sinuate lateral extensions and possess 6–8/1/3–5 denticles. Their mesocone is very prominent, being twice as long as the flanking denticles; these decrease in size towards the outer margin of the teeth. The marginal teeth bear 13–18 denticles of approximately equal size.

Morph b differs significantly from morph a and possibly represents a teratological specimen. The rachidian tooth has a more triangular shape and a V-shaped upper edge. Its cutting edge also tapers to a V-shaped tip. Morph b differs from Morph a most significantly with regard to the denticles on the rachidian. The cutting edge bears 4–5/1/4–5 cuspid denticles. The mesocone is twice as long as the adjacent flanking denticles. Furthermore, three prominent denticles are present on each side of the lateral edges of the rachidian. The foremost of these denticles is twice as long as the next one, which in turn is slightly larger than the third one. The lateral teeth have short lateral extensions that are slightly curved. The cutting edge is V-shaped and bears 3–4/1/3–4 long and cuspid denticles. The mesocone is twice as long as the flanking denticles, which decrease in size towards the margin of the teeth. The marginal teeth are somewhat curved and stand in two serial rows. The inner marginal teeth have a sickle-shaped cutting edge, lacking any denticles, the outer marginal teeth bear 8–10 small denticles of about equal size.

Distribution ( Fig. 18 ). Pseudocleopatra dartevellei is only known from the lower Congo River in the vicinity of Matadi.

Remarks. The record of P. dartevellei from the White Nile in Sudan ( Ahmed 2014) certainly belongs to another species. We interpret the aberrant radula of a probable paratype from Île des Princes (MRAC 146342) to be teratological as the shell was not different from other type specimens. Future studies should test this using molecular techniques. 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 15. Shells of Pseudocleopatra dartevellei Mandahl-Barth, 1973. A. Holotype, MRAC 799161. B. Probable paratype, Matadi; MRAC 260702. C–D. Probable paratypes, Matadi, MRAC 260702, growth series. Scale bar: 5 mm.

FIGURE 16. Radula of Pseudocleopatra dartevellei Mandahl-Barth, 1973 (Morph a), probable paratype, Île des Princes, MRAC 146342. A. Radula ribbon, scale bar: 10 μm. B. Lateral and central teeth, scale bar: 10 μm. C. Cutting edge of lateral and central teeth, scale bar: 10 μm. D. Central, lateral and marginal teeth, scale bar: 10 μm.

FIGURE 17. Radula of Pseudocleopatra dartevellei Mandahl-Barth, 1973 (Morph b), probable paratype, Île des Princes, MRAC 146342. A. Radula ribbon, scale bar: 10 μm. B. Lateral and central teeth, scale bar: 10 μm. C. Cutting edge of lateral and central teeth, scale bar: 2 μm. D. Central, lateral and marginal teeth, scale bar: 10 μm.

FIGURE 18. Known occurrence records of Pseudocleopatra dartevellei Mandahl-Barth, 1973 in the Congo River system. The asterisk indicates the type locality; solid symbols indicate samples with alcohol material, open symbols those of dry material. The arrow indicates the approximate location of the Inga dams.