[Mollusca • 2023] Cryptosemelus niger • A New Species of the Dancing Semislug Cryptosemelus Collinge, 1902 (Eupulmonata: Ariophantidae) from Loei Province, northeastern Thailand

Cryptosemelus niger S. Tumpeesuwan & C. Tumpeesuwan, 

in Tumpeesuwan, Tanmuangpak & Tumpeesuwan, 2023. 

หอยหางดิ้นสีนิล  ||  DOI: 10.3897/zookeys.1163.103650

Abstract

In this study, we describe a new dancing semislug from a limestone hill area in northeastern Thailand. Cryptosemelus niger sp. nov. differs from the three recognized congener species from western and southern Thailand, due to differences in their body and shell lobes coloration, appearance of penial caecum, shape and surface texture of penis and epiphallus, and radula formula and morphology.

Keywords: Genital system, karst topography, limestone hill, mantle extensions, protective behavior, shell lobes

Cryptosemelus niger S. Tumpeesuwan & C. Tumpeesuwan, sp. nov.
 A shell morphology of holotype NHMSU-00054 B living snail.

Photograph by Kitti Tanmuangpak

Cryptosemelus niger S. Tumpeesuwan & C. Tumpeesuwan, sp. nov.
Living snail in natural habitats. Photograph by Chanidaporn Tumpeesuwan 12 December 2018 A C. niger crawling on soil in limestone crevice (white circle) B close-up view in living position C, D semislug was moved to green leaf for taking photo C left side represents left shell lobe (lsl) D right side represents right shell lobe (rsl), left shell lobes (lsl), and left dorsal lobe (ldl).

 

Superfamily Helicarionoidea Bourguignat, 1877

Family Ariophantidae Godwin-Austen, 1883

Subfamily Ostracolethinae Simroth, 1901

Genus Cryptosemelus Collinge, 1902

 Cryptosemelus niger S. Tumpeesuwan & C. Tumpeesuwan, sp. nov.

 

Cryptaustenia sp. Tanmuangpak 2016: 109–110.

Cryptaustenia sp. Chimsaeng 2019: 41–42.

Diagnosis: Animal with blackish body, shell lobes with blackish reticulated skin (Figs 2, 3). Genitalia with very short cylindrical vagina, smooth elongated cylindrical epiphallus, without penial caecum (Fig. 4). Radula with bicuspid lateral teeth (Fig. 5B, C).

Etymology: The species name “niger” is derived from Latin word, meaning “black” referring to blackish body and mantle extensions.

 

 Sakboworn Tumpeesuwan, Kitti Tanmuangpak and Chanidaporn Tumpeesuwan. 2023. New Species of the Dancing Semislug Cryptosemelus Collinge, 1902 (Eupulmonata, Ariophantidae) from Loei Province, northeastern Thailand with A Key to Genera of mainland Southeast Asian Semislugs and A Key to Species of the Genus. ZooKeys. 1163: 47-59. DOI: 10.3897/zookeys.1163.103650