Cryptosemelus niger S. Tumpeesuwan & C. Tumpeesuwan, 2023

Tumpeesuwan, Sakboworn, Tanmuangpak, Kitti & Tumpeesuwan, Chanidaporn, 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, pp. 47-59 : 47

publication ID	https://dx.doi.org/10.3897/zookeys.1163.103650
publication LSID	lsid:zoobank.org:pub:2DB90CB6-E746-4887-B71B-A5D7D7092CEF
persistent identifier	https://treatment.plazi.org/id/FA7C7967-4A62-4A6E-992C-4BE2E6DC9B36
taxon LSID	lsid:zoobank.org:act:FA7C7967-4A62-4A6E-992C-4BE2E6DC9B36
treatment provided by	ZooKeys by Pensoft
scientific name	Cryptosemelus niger S. Tumpeesuwan & C. Tumpeesuwan
status	sp. nov.

Treatment

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

Figs 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4

Cryptaustenia sp. Tanmuangpak 2016: 109-110.

Cryptaustenia sp. Chimsaeng 2019: 41-42.

Type material.

Holotype. NHMSU-00054 (Fig. 3 View Figure 3 ). Phu Pha Lom limestone area, Mueang Loei District, Loei Province, northeastern Thailand, coll. Kitti Tanmuangpak, Nov. 2012. Paratypes. NHMSU-00055. Same locality and same date as holotype.

Type locality.

Phu Pha Lom limestone area, Mueang Loei District, Loei Province, Thailand.

Diagnosis.

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

Description.

(empty shells = 8, living specimen = 4) Shell (Fig. 2A View Figure 2 ). Shell globose, small size (shell height 6.03 ± 0.71.00 mm, shell width 9.72 ± 1.32 mm), shell imperforate, thin, smooth, dark brown color; transparence, aperture large (aperture height 5.28 ± 0.68 mm and aperture width 5.71 ± 0.81 mm).

Genital system (N = 3) (Fig. 4 View Figure 4 ). Atrium (at) short. Penis rather long and cylindrical, with thin penial sheath covering entire penis. Penial retractor muscle (prm) present, short, thin and attached at junction of e1 and e2. Epiphallus (e1+e2) length is slightly equal to penis length, surface smooth, e1 cylindrical and gradually smaller in diameter, e2 cylindrical and larger than e1. Flagellum absent. Vas deferens long. Vagina is shorter than penis, cylindrical. Gametolytic duct (gd) thickened at base, gametolytic sac (gs) swollen gland at distal end. Free oviduct (fo) is shorter than vagina. Uterus and prostate gland long and stout.

Radula (N = 3) (Fig. 5 View Figure 5 ). Teeth arranged in a wide V-shape with half row formula: 1-7-70+teeth. Central teeth symmetric tricuspid. Lateral teeth and marginal teeth gradually changing from broad to narrow bicuspid.

External appearance (Figs 2B View Figure 2 , 3 View Figure 3 ). Living semislug with reticulated skin, blackish to dark body marked by conspicuous grooves running downward. Four mantle extensions well developed and same color body. Shell lobes do not cover entire shell. Caudal horn absent.

Etymology.

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

Distribution, habitat and behavior observations.

Cryptosemelus niger sp. nov. is a species restricted to the dry evergreen forest that covers the Phu Pha Lom limestone area, Loei Province, Thailand. We searched after rain and found the specimens normally hiding on the ground and in the leaf litter. When the snails were disturbed, they escaped by quickly flipping and waging their tail. Information on its natural predators is unknown, but the carnivorous land snails, Discartemon sp., Oophana sp. ( Streptaxidae ), and Sinoennea loeiensis Tanmuangpak & S. Tumpeesuwan, 2015 ( Diapheridae ) were found in the same locality ( Tanmuangpak et al. 2012; Tanmuangpak et al. 2015; Tanmuangpak 2016).

Remarks.

Cryptosemelus niger sp. nov. differ from other Cryptosemelus species by its black body and mantle lobes. The shell seems to have a more rapidly descending whorl than in C. gracilis and C. betarmon , but is similar to C. tigrinus . Cryptosemelus gracilis also lack a penial caecum but differs in the undulated surface patch on the proximal part of e2. The epiphallus and penis are cylindrical without a caecum, diverticulum, and granulate surface. The radula of the new species differs from all Cryptosemelus in having bicuspid lateral teeth, whereas other species have tricuspid lateral teeth (Table 2 View Table 2 , Figs 2A, B View Figure 2 , 3A-D View Figure 3 , 4 View Figure 4 , 5B-D View Figure 5 ).