Sulawesidrobia tilangaensis sp. nov.

Etymology.

This species is named after the type locality, the Tilanga natural Pool.

Material examined.

Holotype (Fig. 2 C): Indonesia • Sulawesi, Tana Toraja Regency, Makale Utara, Tilanga natural Pool, on karstic rocks. 3°02'05.6"S, 119°53'14.3"E. October 2023, Muhammad Iqram leg. MZB Gst. 12189 .

Paratypes (Fig. 3 E, F): Indonesia • N = 4; same collection data as for holotype; MZB Gst. 12190 . N = 3; same collection data as for holotype; ZMB 118373 .

Diagnosis.

This new species is among the smaller and wider conical species of Sulawesidrobia morphologically falling into the variation of S. bonnei . It is characterized by fixed bases at 18 diagnostic positions in the COI alignment not shared with S. bonnei, S. bulat, or S. posoensis, which are reciprocally paraphyletic (for details see Remarks).

Shell. (N = 5). Conical, short, 1.4 to 1.6 times higher than wide, 3.25 to 3.75 whorls, sutures shallow, whorls moderately convex, semitranslucent, light brown, periostracum without color (Figs 2 C, 3 E, F); protoconch (N = 1) wrinkled with slightly more than 1 whorl (Fig. 4 C), teleoconch with growth lines, otherwise without structure; umbilicus a narrow slit, outer lip straight.

Remarks.

Only five adult specimens could be morphologically examined. Therefore, i. e. because of the lack of anatomical data, the differentiation and diagnosis had to be restricted to genetic data. Phylogenetically, S. tilangaensis sp. nov. was nested among the species from Lake Poso with a long branch indicating considerable genetic differentiation (Figs 10, 11). Morphologically, the new species is similar to S. bonnei (see Haase and Bouchet 2006). As S. bonnei cannot be distinguished from S. bulat and S. posoensis based on mitochondrial data due to paraphyly (Zielske et al. 2011, see below), the new species was compared against those three species. Sulawesidrobia tilangaensis sp. nov. had diagnostic bases at 18 positions (type 1 sensu Kühn and Haase 2018) in the COI alignment (Suppl. material 1): position 50 (base C), 157 (T), 181 (G), 200 (A), 265 (G), 286 (G), 301 (G), 340 (T), 370 (G), 397 (C), 454 (G), 481 (G), 484 (G), 511 (G), 532 (C), 544 (G), 577 (G), 578 (C).