Satsuma nivnu, Hwang & Wu, 2024

Hwang, Chung-Chi & Wu, Shu-Ping, 2024, Three new species of Satsuma Adams, 1868 (Gastropoda, Camaenidae) from Taiwan, Zoosystema 46 (3), pp. 61-76 : 66-70

Satsuma nivnu n. sp.

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( Fig. 5 )

urn:lsid:zoobank.org:act:EFF743A3-16B4-4648-BC40-D405E43840B5

TYPE MATERIAL. — Holotype. Taiwan • Jiayi County, Alishan Township, Shitz Village , Dadongshan forest trail; 23°29’52”N, 120°43’11”E; alt. 1970 m a.s.l.; 14.VIII.2020; S. P. Wu leg.; NMNS-8676-005 ; SH 31.8 mm, SW 39.4 mm.

Paratypes. Taiwan • 6 specimens; same data as holotype; NMNS-8676-006 • 2 specimens; from type locality; VIII.2014; C. F. Lin leg.; NMNS-8676-007 , MNHN-IM-2022-13918 • 2 specimens; from type locality; 9.VIII.2022; S. P. Wu leg.; NMNS-8676-008- 009 • 1 specimen; from type locality; 26.VIII.2020; S. P. Wu leg.; UTM-2023002 • 1 specimen; from type locality; 26.VIII.2020; S. P. Wu leg .

ETYMOLOGY. — Nivnu, treated as a simple noun in apposition, is the goddess of creation and agriculture in the mythology of the indigenous Tsou race.

TYPE LOCALITY. — Taiwan, Jiayi County, Alishan Township, Shitz Village , Dadongshan forest trail ; 23°29’52”N, 120°43’11”E; alt. 1970 m a.s.l.

DISTRIBUTION. — This species was found in type locality, Alishan National Forest Recreation Area, and Tefuya Ancient Trail.

DIAGNOSIS. — Shell dextral, conical, medium to large sized (SW> 35 mm); spiral striation weakly malleated above and below periphery;; whorl not descending behind aperture; upper lip smoothly curved; columellar lip oblique, almost straight; basal lip curved; umbilicus partly open; penis with a muscular and bulging penial pouch; penial caecum conical and short; epiphallus swollen basally.

DESCRIPTION

Shell dextral, with conical spire, brown to dark brown with red-brown peripheral band and umbilicus spot; thin and pale brown area visible immediately below suture and peripheral band. Apex acute.Whorls regularly increasing, slightly convex, not descending behind aperture. Periphery almost round, very weakly angulated. Base of shell convex. Surface covered with small, dense, elongate, axial granules on apical 3.5 whorls, becoming loose, coarse, continuous, oblique axial ridges that are weak on base ( Fig. 7B ); spiral striation wavy and loose on base of shell, becoming weakly malleated above and below periphery. Aperture roundly lunate, light purplish inside. Peristome expanded; outer lip smoothly curved; columellar lip oblique, almost straight, joining curved basal lip in an angle. Parietal callus absent. Umbilicus partly open, c. 1/5 covered by reflected columellar lip, with 2-3 clear creases.

Measurements

SH 28.9-32.9 mm, SW 36.3-42.6 mm, AH 17.5-20.3 mm, AW 23.0- 26.8 mm, W# 6.25-6.75, protoconch 2.5 whorls, SH/SW 0.726 -0.822 (n = 12).

External morphology ( Fig. 5D )

Brown with irregular, small, dark brown spots and a distinct yellowish line running from head between tentacles to collar. Tentacles dark grey.

Reproductive system

Bursa copulatrix oval. Pedunculus of bursa copulatrix as long as spermoviduct, 33.7-43.5 mm, thickened basally, gradually slender toward bursa copulatrix. Free oviduct short, 9.7- 11 mm. Vagina slender, 22.1-25 mm in length, as thickened as penis, smooth externally, with 13-15 thin internal pilasters. Atrium short, coarsely wrinkled inside. Penis elongate, 21.6-28.7 mm in length; slender shortly near atrium with smooth interior, becoming bulging penial pouch ( Fig. 5B ) with 6-11 smooth and muscular internal pilasters; apparently thickened near epiphallus, twice the thickness of distal portion, furrowed and striped externally corresponding to 16-18 strong, straight, corrugated pilasters internally. Penial caecum conical, short, 2.1-2.7 mm. Verge extending along penial caecum, fusiform, with smooth surface. Epiphallus slender, 8.3-13.9 mm in length, internally with 2 major and 2-3 minor pilasters. Penis retractor muscle attached at basal 1/10-1/5 of epiphallus. Flagellum 6.7-7.8 mm; swollen basally, internally with thick swelling extending from epiphallic pilasters, opening into vas deferense at base; tapering toward tip, internally with 3-5 pilasters.

REMARKS

The new species is similar to S. arisana ( Kuroda, 1941) , S. tani ( Kuroda, 1941) , and S. longkiauwensis Wu, Lin & Hwang, 2007 in Taiwan, S. myomphala (Martens, 1865) in Japan, and S. mercatoria in Okinawa Island in having a large shell that is wider than 40 mm. Satsuma arisana , S. myomphala , and S. tani have the umbilicus completely covered by a reflected columellar lip. The former two species have been dissected for their genitalia ( Azuma 1995; Chang 1997) which lack a penial pouch near the atrium and a basally swollen flagellum. Satsuma longkiauwensis has a lower shell (SH/SW = 0.718 vs 0.726 -0.822 in S. nivnu n. sp.), lighter shell colour, a more covered umbilicus, an unapparent penial caecum, and a short, truncated oval penial verge that is not extended along penial caecum ( Wu et al. 2007). Satsuma mercatoria has a lower shell, lighter shell colour, descending behind aperture, weaker spiral striations on the base of the shell, and the absence of a penial pouch ( Azuma 1995). The new species is similar to S. hsuehshan n. sp. in having conical spire and a penial pouch. Satsuma hsuehshan n. sp. has a smaller shell (maximum SW = 27.0 mm), denser spiral striation on base of shell, a stronger penial pouch than the present new species.

Figures

FIG. 5. — Shell and reproductive system of Satsuma nivnu n. sp.: A, shell of holotype (NMNS-8676-005); B, C, genitalia (paratype NMNS-8676-006):whole genitalia (B), opened genitalia (C); D, living animal. Scale bars: 10 mm. Abbreviations: see Material and methods.

FIG. 7. — Shell sculptures on the 3rd whorl (A, B, C); surface of the last whorl (D, E, F); shell base (G, H, I): A, D, G, Satsuma hsuehshan n. sp.; B, E, H, Satsuma nivnu n. sp.; C, F, I, Satsuma sunlinksea n. sp. Scale bars: A-C, 0.5 mm; D-I, 1 mm.