Satsumaguandi, Zhang & Zhu & Lyu, 2019

Satsumaguandi View in CoL n. sp.

Figures 3 View Figure 3 , 4 View Figure 4

Holotype. China: Guangdong Province, Shaoguan City, Wengyuan County, Mountains near Longxian Town . 24° 19’9"N, 114°15’17"E; 574 m a.s.l. Coll. Jian-Wei Chen, Sept. 2017. Shanghai Natural History Museum ( SNHM) (WY1) GoogleMaps .

Paratypes. from the type locality. Shanghai Natural History Museum ( WY 2), second author’ s private collection (5 specimens) ( WY 3-7). GoogleMaps

Material examined

Type material: See above. Other material: None.

Diagnosis

Shell sinistral, periphery strongly keeled; umbilicus open; aperture and umbilicus dark brownish-red; a weak tooth at the inferior lip. Penial caecum long, about 1/3 of the length of penis; flagellum fairly short; pedunculus base expanded.

Description

Shell ( Figure 3A View Figure 3 , Table 1 View Table 1 ): Sinistral, depressed conical, thin, medium-sized. Apex obtuse. Periphery strongly angulated with narrow keel extended to peristome. Base inflated. Periostracum smooth and glossy, with fine spiral striae, brownish-yellow. The keel on the periphery of body whorl reddish brown. Aperture diagonal, ovatelunate. Peristome thin, expanded, reflected, dark brownish-red. The inner part of the inferiorlip close to the columellar lip slightly thickened and convex, forming a weak tooth. Columellar lip oblique and reflected, covering about 1/4 of umbilicus. Columelladark brownish-red. Parietalcallus very thin, less glossy than periostracum. Umbilicus open, narrow, deep, dark brownish-red.

External morphology ( Figure 3B–C View Figure 3 ): Light brown body with many irregular black spots, especially at the posterior region. Ablurred yellow line running from head between tentacles to collar.

Reproductive system ( Figure 4 View Figure 4 , Table 2 View Table 2 ): Bursa copulatrix small, oblong, pedunculus thin and long, pedunculus base noticeably expended and about 1/3 length of pedunculus, with 15 well-developed internal folds. Sperm oviduct long. Vagina short and thin. Penis long and thickened, about twice as long as vagina, with 13–14 internal folds. Penial caecum acute and long, about half as long as penis, with two strong caecal pilasters, remaining inner walls with 12–14 weak longitudinal folds. Epiphallus slender, almost as long as penis, with 2–3 internal folds. Flagellum short, more slenderthanepiphallus, about 1/10 length of epiphallus. Vas deferens long, thin.

Distribution

Wengyuan County (type locality) and Nankun Mountain in Guangdong Province, China.

Ecology

Herbivorous snails, feeding on fungus or living leaves, based on observation and feeding in the laboratory; inhabiting very moist habitats, such as the undergrowth beside streams; semi-arboreal, found on the ground, crawling on rocks, lower tree trunks or leaves.

Comparative remarks

Satsuma guandi n. sp. is more strongly angulated than any other known sinistral Satsuma species. Satsuma contraria (Pilsbry & Hirase, 1909) is also angulated but less prominently than the new species. Satsuma guandi n. sp. also differs from S. contraria in having a dark brownish-red peristome and columella, a weak tooth at the inferior lip (marked in Figure 3 View Figure 3 by arrow) and the columellar lip covering 1/4 of umbilicus. The dextral species Satsuma mellea (Pfeiffer, 1866) has a similar shape and colour pattern. In addition to its different chirality, Satsuma guandi n. sp. also differs from S. mellea in its dark brownish-red peristome. Additionally, the spiral whorls of S. mellea are more depressed than in Satsuma guandi n. sp.

The genital anatomy (especially long penial caecum, short flagellum and expanded pedunculus base) of S. guandi differs from all known genital structures of sinistral Satsuma species (the genital structures of three sinistral species from mainland China and one from Taiwan are unknown) and Satsuma mellea ( Table 3 View Table 3 ). The genital anatomy of the type species of Satsuma , Satsuma japonica (Pfeiffer, 1847) , is also included for comparison.

Etymology

Named for a Chinese god Guan Di (关帝), the god of war in Taoist mythology, which is popular folk belief in Guangdong, including the type locality Shaoguan City. Guan Di is also famous for his maroon coloured face. The aperture and umbilicus of this species is similarly dark brownish-red; formed as a noun in apposition.

Discussion

Satsuma is a diverse genus endemic to East Asia except for one species found on Batan Island of the Philippines, with many species on various islands in the region. Here we report the fourth Satsuma species from mainland China. Both molecular phylogenetics and morphology support that this sinistral species is a new member of Satsuma .

The phylogenetic tree shown here largely agrees with the phylogeny presented by Hoso et al. (2010) based on a nearly identical dataset of Satsuma species. We included additional sequences of the new species and the two sinistral Satsuma species from mainland China from Wang et al. (2014), who presented an ML tree including a few Satsuma species. According to our phylogeny, the three sinistral Satsuma from mainland China belong to three different lineages within the genus. S. meridionalis from Mainland China is the only sinistral species within its clade, while all other members are dextral species from three of the major islands of Japan. The new species S. guandi is a derived species, although the current limited resolution of topology does not validate which is its sister taxon.

Satsuma lavea was apparently misidentified by Wang et al. (2014) as S. uncopila , which differs by its depressed conic shell with fine periostracal hairs according to the original description (Heude 1882). According to the Wang et al. (2014) description and figures, this species with spherical shell without periostracal hairs should be identified as S. laeva with reference to the original description by Pilsbry and Hirase (1908).

Among 13 sinistral taxa known in Satsuma ( Table 3 View Table 3 ), 10 (including the present new species) occur most probably in the distribution range of the snail-eating snake genus Pareas ( Figure 1 View Figure 1 ). According to their right-handed mandibular asymmetry, most Pareas snakes are probably specialised in the predation of the majority dextral snails (Hoso et al. 2007). The present molecular phylogeny of Satsuma ( Figure 2 View Figure 2 ) shows that at least eight of the 12 sinistral taxa (including undescribed species) evolved phylogenetically independently of one another. The genital structure of sinistral Satsuma formosensis (Pfeiffer, 1866) is unknown. Our results of molecular phylogeny provided no evidenceforits recognitionasadistinct genus. Based on shell morphology, three additional sinistral snail species distributed in mainland China probably belong to Satsuma : Satsuma (?) fortunei (Pfeiffer 1850), Satsuma (?) uncopila (Heude 1882) and Satsuma (?) latilabris (Möllendorff, 1874). The threespecies have similar morphology to Satsuma meridionalis according to the plate of type specimens of Yen (1939). These species also mostly occur in the range of Pareas snakes according to the available records ( Figure 1 View Figure 1 ). However, to confirm our assumption, comparative studies of genitalanatomy and molecular phylogeny are required.

Satsuma mellea is the only Satsuma species distributed in both mainland and island environments (Wang et al. 2014). S. meridionalis , S. lavea , S. guandi and S. mellea represent a few known descendants of Satsuma on the mainland. Since the sampling of Satsuma at the species level from islands is exhaustive, further studies of the genus should search for more potential species of Satsuma on the mainland.