Bradybaena linjun Wu & Chen

Wu, Min, Chen, Zheyu & Zhu, Xiaoran, 2019, Two new camaenid land snails (Eupulmonata) from Central China, ZooKeys 861, pp. 129-144 : 136-141

publication ID	https://dx.doi.org/10.3897/zookeys.861.35430
publication LSID	lsid:zoobank.org:pub:DAD076A6-B8B7-4FEE-94C4-CFB56E0B6338
persistent identifier	https://treatment.plazi.org/id/834A1B9F-7272-4188-9FD5-2121A9D26443
taxon LSID	lsid:zoobank.org:act:834A1B9F-7272-4188-9FD5-2121A9D26443
treatment provided by	ZooKeys by Pensoft
scientific name	Bradybaena linjun Wu & Chen
status	sp. nov.

Treatment

Bradybaena linjun Wu & Chen sp. nov. Figs 1 View Figure 1 , 7 View Figure 7 , 8 View Figure 8 , 9 View Figure 9 , 10 View Figure 10

Material examined.

Holotype, fma (HBUMM08241-specimen 1, Fig. 7A View Figure 7 ). Hubei Province, Yichang, Changyang Tujia Autonomous Prefecture, Longzhoupin; 31°28'9"N, 111°11'14"E, 103 m a. s. l.; 2018-VII; coll. Chen, Zheyu. Paratype, 1 fma (HBUMM08241-specimen 2, Fig. 7B View Figure 7 ), the same collection information as holotype. Foot muscle was cut off and preserved in 99.7% alcohol at -20 °C (HBUMM08242).

Diagnosis.

Shell depressed; dextral. Columella oblique. Periphery rounded. A peripheral and a supraperipheral chestnut band present. Penis internally with numerous crossing pilasters of equal thickness that form a network. Love dart hollow and C-shaped in cross section. Accessory sac externally invisible. Mucous glands two, very short thyrsiform (not branched) tubes; entering accessory sac through simple pore. Shell about 4.5 whorls, breadth 13-17 mm.

Description.

Shell ( Fig. 7 View Figure 7 ). Depressed; thin; dextral. Whorls convex. Suture impressed. Half umbilicus covered by reflexed columellar lip. Columella oblique. Proto conch not granulate, smooth. Teleoconch with dense spiral furrows. Aperture oblique; not sinuate at peristome. Body whorl slightly descending behind aperture. Shell surface without ribs. Growth lines fine. Adult shell not hairy or scaly. Adult body whorl rounded at periphery; basally convex. Ring-like thickening within aperture absent. Peristome thin; slightly reflexed. Callus thin and transparent. Shell glossy; uniformly brownish yellow; with a peripheral and a supraperipheral chestnut bands. Measurements (holotype is larger in size): shell height 8.8-10.7 mm, shell breadth 13.2-16.6 mm, aperture height 5.9-6.0 mm, aperture width 7.0-9.7 mm, embryonic shell whorls 1.625, whorls 4.250-4.625, shell height/ breadth ratio 0.64-0.67.

General anatomy ( Figs 8 View Figure 8 , 9F View Figure 9 ). A high head wart between ommatophores present ( Fig. 8A, C View Figure 8 ). On corresponding internal body wall no particular structure present ( Fig. 8D View Figure 8 ). On left side of mantle edge, a leaf-shaped appendage present ( Fig. 8B View Figure 8 , arrowed). Body light brown; with whitish striae posterior to wart. Sole creamy white. Jaw arcuate; with about thirteen more or less projecting ribs ( Fig. 9F View Figure 9 ).

Genitalia ( Fig. 9 View Figure 9 ). Membranous sac surrounding terminal genitalia present ( Fig. 9A, B View Figure 9 ). Penis sheath about 1/3 penis length. Penis very thick; externally simple. Penial retractor muscle inserting on epiphallus. Epiphallus slightly thicker than vas deferens. Flagellum absent. Epiphallic papilla absent ( Fig. 9D View Figure 9 ). Penis internally with numerous crossing pilasters of equal thickness that form a network ( Fig. 9D View Figure 9 ). Dart sac present. Love dart spoon-shaped, hollow and C-shaped in cross section (observed in holotype, Fig. 9E View Figure 9 ). Accessory sac invisible externally ( Fig. 9C View Figure 9 ). Poly-layered structure present between mucous gland insertion and vagina. Mucous glands two tubes; much shorter than dart sac in length; each thyrsiform rather than branched ( Fig. 9A, C View Figure 9 ); entering accessory sac through simple pore. Vagina about half of penis in length. Measurement of holotype: DS– 4.6 mm long, 1.4 mm broad; MG– 1.7 mm; PS– 1.2 mm; P– 7.1 mm; Ep– 2.6 mm; VD– 21.5 mm; PR– 1.7 mm; Va– 4.5 mm; FO– 2.8 mm.

Etymology.

The new species is named after the legendary tribal leader "Lin-Jun ( 廪君)” of the Tujiazu people who live at the type locality.

Distribution.

Hubei (Changyang), only known from the type locality.

Ecology.

This species was found living in a well-established secondary forest, on limestone cliffs, often in cracks ( Fig. 10 View Figure 10 ). A large number of broken shells, presumably caused by bird predation, were observed at the type locality.

Taxonomic remarks.

The new species is assigned to Bradybaena because of the presence of a smooth protoconch, membranous sac surrounding terminal genitalia, poly-layered structure in dart apparatus, two mucous glands and the absence of a flagellum; characters that are consistent with the type of the genus B. similaris ( Wu 2004).

On the left side of the mantle edge, this species possesses a leaf-shaped appendage ( Fig. 8B View Figure 8 ). The existence of this structure in other bradybaenine genera is not known except in Sinochloritis lii Wu & Chen, gen. & sp. nov. described here ( Fig. 3D, E View Figure 3 ). In our other work on Bradybaena this structure is observed ( Bradybaena sp., HBUMM06125, Wuyuan, Jiangxi Province, 147 m, 29°22'18.8"N, 118°02'45.2"E, 2007-V-26; unpublished data).

Only a few Chinese species in the subfamily Bradybaeninae have double bands. The double-banded shells occur more frequently in Cathaica Möllendorff, 1884 than in Bradybaena where only four species exhibit double bands, namely B. billiana (Heude, 1882), B. mimicula (Heude, 1888), B. diplodesma ( Möllendorff, 1899), B. sueshanensis Pilsbry, 1934 ( Heude 1882, 1888; Möllendorff 1899; Pilsbry 1934). Although the new species has double bands, in aspect of shell morphology it most resembles B. qixiaensis Wu & Asami, 2017. However, the new species has very short mucous glands which are proportionally the shortest in the subfamily Bradybaeninae, the thyrsiform mucous gland duct, and the spoon-shaped love dart, which distinguish this species from all Chinese Bradybaena species with known genital anatomy.