Tylomelania baskasti, Rintelen, Thomas Von & Glaubrecht, Matthias, 2008

Rintelen, Thomas Von & Glaubrecht, Matthias, 2008, Three new species of the freshwater snail genus Tylomelania (Caenogastropoda: Pachychilidae) from the Malili lake system, Sulawesi, Indonesia, Zootaxa 1852, pp. 37-49 : 39-41

publication ID	https://doi.org/ 10.5281/zenodo.183429
DOI	https://doi.org/10.5281/zenodo.5621355
persistent identifier	https://treatment.plazi.org/id/5F2DDF50-FFB2-9339-FF26-F85391119A8E
treatment provided by	Plazi
scientific name	Tylomelania baskasti
status	sp. nov.

Treatment

Tylomelania baskasti sp. nov.

Type material. Indonesia, Sulawesi, Larona River: Holotype ( Fig. 2 View FIGURE 2. T A; 52.3 mm x 17.7 mm, loc. 71-02), MZB Gst. 12.109; paratypes ( Fig. 2 View FIGURE 2. T B-D): loc. 14–02, MZB Gst. 12.110, n=5; ZMB Moll. 190533, n=7; loc. 15-02, MZB Gst. 12.111, n=12; ZMB Moll. 190534, n=16; loc. 71-02, MZB Gst. 12.112, n=14; ZMB Moll. 190535, n=17.

Etymology. The new species has been named baskasti in honour of Bas Kast, who has generously supported research on these snails at the Museum für Naturkunde.

Description. Shell ( Fig. 2 View FIGURE 2. T A–D): Medium sized to large, brown, elongate conic, spire angle 13–25°. Top whorls in adult specimens always corroded to a varying degree, 4–9 remaining whorls, can reach up to 54.7 mm ( Tab. 1 View TABLE 1 ). With spiral ribs only. Aperture oval, pointed at top and slightly siphonated at base. Columella and interior of aperture brown, in few specimens slightly whitish coating.

External morphology: Headfoot black with fine orange dots, sometimes rather dense, foot more intensely pigmented, mantle edge serrated to a varying degree. Body coiled in 3–6 whorls.

Operculum ( Fig. 2 View FIGURE 2. T E,F): roundish-ovate, last whorl inflated, multispiral with 5–7 whorls (n=3).

Radula ( Fig. 3 View FIGURE 3. T A,B): 160–194 rows, 16.4–24.2 mm long, on average 8.8 teeth per mm (n=12). Central tooth with pointed and enlarged major denticle. Glabella with very slightly rounded base. Lateral teeth with pointed and enlarged major denticles and 2–3 minor denticles on each side. Marginal teeth shovel-like, inner and outer marginals with three almost equal-sized denticles each.

Reproductive biology: Brood pouch contains 4–12 embryos, their size can reach 8.4 mm (n=5) (Tab. 3).

Embryonic shells ( Fig. 3 View FIGURE 3. T C–E): Elongate-conic, axial ribs emerging on the 2nd to 3rd whorl and fading on the 5th whorl. Spiral striae emerge on 3rd to 4th whorl (Tab. 3).

Distribution and habitat. South Sulawesi, lower reaches of Larona River ( Fig. 1 View FIGURE 1 B).

This species was collected in shallow water (0.1–0.5 m depth) in less turbulent zones at the river bank on soft substrate. As deeper parts of the river were not accessible for sampling because of strong currents, T. baskasti must not necessarily be restricted to shallow water.

Taxonomic remarks. Shell shape and radula of T. baskasti are similar to that of T. lalemae ( Kruimel, 1913) from Lake Towuti. The shell of T. baskasti is more fragile and always lacks the conspicuous white aperture of T. lalemae , though. The radula of T. baskasti also closely resembles that of all other described riverine species of Sulawesi such as e.g. T. perfecta (Mousson, 1849) . T. baskasti can be unambiguously distinguished from those taxa by its characteristic shell and the molecular data clearly confirm its relationship to the Malili lakes species flock (compare also below, Discussion).