Tylomelania hannelorae sp. nov.

Type material. Indonesia, Sulawesi, Lake Mahalona, loc. 56-03: Holotype (Fig. 6 A; 11.8 mm x 5.5 mm), MZB Gst. 12.114; paratypes (Fig. 6 B), MZB Gst. 12.115, n=3; ZMB Moll. 190713, n=5.

Etymology. The new species has been named hannelorae in honour of Hannelore Glaubrecht, for her emotional participation in our Sulawesi research.

Description. Shell (Fig. 6 A,B): Small, dark brown, elongate conic, spire angle 11–17°. Top whorls in adult specimens always corroded to a varying degree, 3–5 remaining whorls, can reach up to 13.9 mm (Tab. 2). Axial and spiral ribs form reticulated pattern. Aperture oval, pointed at top and slightly siphonated at base. Columella and interior dark brown.

External morphology: Headfoot black, mantle edge serrated to a varying degree.

Operculum (Fig. 6 C): ovate, last whorl strongly inflated, multispiral with 10 whorls.

Radula (Fig. 6 D,E): 28–44 rows, 2.1–3.2 mm long, on average 13.7 teeth per mm (n=5). Central tooth with very large and elongate squarish major denticle and one minor denticle on each side. Glabella narrow, with convex base. Lateral teeth with very much enlarged squarish major denticles and one minor denticle on each side. Marginal teeth shovel-like, inner and outer marginals with three denticles each, the outermost ones considerably wider than the inner ones.

Reproductive biology: Brood pouch contains 1–2 embryos, their size can reach 3.1 mm (Tab. 3).

Embryonic shells (Fig. 6 F–H): Ovate-conic, with strong axial ribs emerging on the 2nd to 3rd whorl and fading on the 5th whorl. Shallow, widely spaced spiral ribs emerge on 3rd to 4th whorl (Tab. 3).

Distribution and habitat. South Sulawesi, Lake Mahalona, cape on NW shore (Fig. 1 B).

This species was collected on rocks in shallow water (less than 0.5 m depth).

Taxonomic remarks. T. hannelorae is the smallest species within the Malili lakes species flock. Its size in combination with the reticulate shell sculpture generally can serve to distinguish it unambiguously from all other species in the system. While T. hannelorae might be mistaken for subadult specimens of T. confusa Rintelen, Bouchet & Glaubrecht, 2007, at first glance, the shell corrosion of the upper whorls characteristic for older animals will allow identifying any specimen as a fully grown adult.

Molecular phylogeny. The topology of the 16S ML phylogram based on 851 bp of mitochondrial 16S rDNA (Fig. 7) is basically identical to the tree presented in Rintelen et al. (2004) except for the inclusion of two of the new species described here, T. baskasti and T. sinabartfeldi (all attempts to sequence T. hannelorae failed). Both species belong to a clade of smooth-shelled or spirally-ribbed taxa (clade Malili 2, compare Rintelen et al. 2004, 2007), where they form a poorly supported subclade which is sistergroup to all remaining species of clade Malili 2 but for one individual of T. sarasinorum (Kruimel, 1913) from the outlet bay of Lake Towuti clustering with T. baskasti and T. sinabartfeldi. While the three haplotypes of T. sinabartfeldi are identical, T. baskasti appears paraphyletic with an intraspecific sequence divergence of 0.6% (p-distance).