Satsuma mellea stenozona (Moellendorff, 1884)

Wang, Pei, Xiao, Qiong, Zhou, Wei-Chuan & Hwang, Chung-Chi, 2014, Revision of three camaenid and one bradybaenid species (Gastropoda, Stylommatophora) from China based on morphological and molecular data, with description of a new bradybaenid subspecies from Inner Mongolia, China, ZooKeys 372, pp. 1-16 : 4-5

Satsuma mellea stenozona (Moellendorff, 1884) Figs 2A; 3A; 4A

Helix stenozona Moellendorff, 1884: 385, pl. 9, figs 5-6.

Euhadra stenozona , Pilsbry, 1890: 119, pl. 27, figs 4-5; Pilsbry, 1895: 214.

Bradybaena stenozona , Yen, 1939: 132, pl. 13, fig. 53.

Ganesella citrina Zilch, 1940: 113-118, pl. 7, fig. 4; 1966: 208, Pl. 5, fig. 26.

Ganesella stenozona , Zilch, 1966: 209, pl. 5, fig. 25.

Bradybaena (Bradybaena) stenozona , Wu, 1999: 99-100, figs 6.52-14, pl. 11B; Chen and Zhang 2004: 140-142, fig. 105.

Satsuma stenozona , Zhou et al., 2011: 52, fig. 1.

Type lo cality.

Fuzhou (26°5'N, 119°18'E), China.

Material examined.

Bradybaena stenozona : Fuzhou, Fujian, Lectotype (SMF 8833), paralectotype (SMF 8832); National Forest Park of Fuzhou, Fujian (May 6, 2007, 26°09'50.36"N, 119°16'55"E; FJIQBC 18220-18237); Drum Mountain of Fuzhou, Fujian (Oct. 16, 2010, 26°03'26"N, 119°24'2"E; FJIQBC 18238-18245); YuHua Hole of Jiangle, Fujian (Jun. 1, 2007, 26°41'59"N, 117°30'55"E, FJIQBC 18146-18250). Ganesella citrina : Guadun, Wuyi Mountain, Fujian, Holotype (SMF 47228), paratypes (SMF 47229); Wuyi Mountain, Fujian (Oct. 12, 2010, 27°39'2"N, 117°58'01"E, FJIQBC 18251-18255).

Shell.

Dextral,medium sized, about 14.5 mm in height, 21.0 mm in width, thin but solid, straw colored, glossy; 5 1/2 whorls. Apex obtuse. Suture deep. Spire low conical, slowly increasing, slightly convex. Body whorl fast expanding, convex, with weakly angulated margin. Periphery bluntly angulated with red-brown peripheral band, extending from apex to columellar lip. Whorls slightly descending at the front. Surface with oblique, curved growth lines, and staggered, delicate spiral lines. Aperture diagonal and round to lunate. Peristome white, slightly expanded and reflected. Inner lip with thin callus only. Basal lip curved. Columellar lip margin slightly expanded. Umbilicus open, small.

Reproductive system.

Penis slender, with a short penial caecum near the penis retractor. Epiphallus as wide as penis, half as long as penis. Flagellum short, about 1/5 of length of epiphallus. Penis retractor muscle thin and long. Vas deferens short. Free oviduct moderately long, slightly inflated. Vagina short. Pedunculus of bursa copulatrix inflated at base, fusiform. Bursa copulatrix oval.

Ecology.

One of the collected sites, Yuhua Hole, Jiangle, Fujian belongs to a Karst land form (limestone), all others are on Danxia land forms (acidic soil). Snails generally live under rotten branches and fallen leaves in forests, and actively crawl on trees during rainy seasons. Population density is generally not high in these locations. In Fuzhou, snails become active in early April, brisk in May and June, lie dormant in the soil by the end of October; juveniles and eggs aestivate during winter. Newly hatched snails will grow into adult in 7-8 months, then mate and spawn, about 100-200 eggs at once. Eggs are large, 1.5-2.0 mm in diameter.

Remark.

This species has been placed in Bradybaena for a long time. Based on a study of the types, Zilch (1966) transferred it to the genus Ganesella , assuming a close relationship with Ganesella mellea mellea (Pfeiffer, 1866) (= Satsuma mellea ) from Taiwan and Ganesella citrina Zilch, 1940 from Wuyi Mountain. However, his classification was not refuted subsequently ( Wu 1999; Chen and Zhang 2004). Eventually, this species was classified as a member of the genus Satsuma by Zhou et al. (2011) for a lack of accessory sac as well as mucous gland, but the authors didn’t provide any molecular evidence.

In the present study, the phylogenetic analyses based on COI showed close phylogenetic relationships and short genetic distances between specimens identified as Satsuma stenozona , Ganesella citrina and Satsuma mellea (Fig. 5). The shell features of Satsuma stenozona from Fuzhou and Ganesella citrina from Wuyi Mountain do not reveal obvious differences. The differences mentioned by Zilch (1940), such as the shell dimensions and color bands, are mere variations between individuals and populations. The molecular phylogeny also indicated that Satsuma stenozona and Ganesella citrina were sister taxa. Therefore, we consider Ganesella citrina a synonym of Satsuma stenozona . Satsuma mellea and Satsuma stenozona may be considered as geographical races of the same species for the rather low amounts of morphological and molecular difference ( Chang 1981; Zhou et al. 2011). Hence, we classified Satsuma stenozona as a subspecies of Satsuma mellea .