Satsuma hsuehshan, 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 : 64-66

Satsuma hsuehshan n. sp.

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( Fig. 2 )

urn:lsid:zoobank.org:act:86FC0BED-7B34-449F-81F2-EE494E132A3C

TYPE MATERIAL. — Holotype. Taiwan • Miaoli County, Taian Township, Simashian forest road , Hsuehjian ; 24°24’17”N, 121°0’25”E; alt. 1740 m a.s.l.; 30 VIII.2020; SP Wu leg.; NMNS-8676-001 ; SH 23.7 mm, SW 27.0 mm.

Paratypes. Taiwan • 3 specimens; same data as holotype; NMNS-8676-002 • 5 specimens; from type locality; 27.VII.2021; SP Wu leg.; NMNS-8676-003-004 , MNHN-IM-2022-13916 • 1 specimen; from type locality; 30.VIII.2022; SP Wu leg.; UTM-2023001 from type locality; 30.VIII.2022; SP Wu leg .

ETYMOLOGY. — The species is named for its distribution area, the Hsuehshan Range, treated as a simple noun in apposition.

TYPE LOCALITY. — Taiwan, Miaoli County, Taian Township, Simashian forest road, Hsuehjian ; 24°24’17”N, 121°0’25”E; alt. 1740 m a.s.l.; middle altitude mixed forest.

DISTRIBUTION. — This species was found in type locality only.

DIAGNOSIS. — Shell dextral, conical, medium sized (SW <35 mm); spiral striation absent above periphery; upper lip weakly sinuous or smoothly curved; columellar lip oblique, almost straight, joining curved basal lip in an angle; umbilicus partly open; penis with a muscular and bulging penial pouch; penial caecum conical and blunt; epiphallus swollen basally.

DESCRIPTION

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

Measurements

SH 20.3-23.7 mm, SW 24.6-27.0 mm, AH 11.6-12.9 mm, AW 14.3-16.4 mm, W# 6-6.25, protoconch 2.5 whorls, SH/ SW 0.781 -0.932 (n = 10).

External morphology

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 to elongated oval. Pedunculus of bursa copulatrix as long as spermoviduct, 26.2-28.1 mm, slightly thickened basally, gradually slender toward bursa copulatrix. Free oviduct short, 4.5-5.2 mm.Vagina 9.7-10.1 mm in length, as thickened as penis, slender at middle, smooth externally, with 11-13 thin, dense, partly undulated internal pilasters. Atrium short, smooth to wrinkled inside. Penis elongate, 11.6-16.1 mm in length, smooth and slender externally; distal portion with a muscular, bulging penial pouch with smooth internal wall ( Fig. 2C, D ); slender at middle, becoming slightly thickened around verge, with 8-10 corrugated internal pilasters extending to penial caecum. Penial caecum conical, blunt, long, 2.4-3.3 mm. Verge narrow drop-shaped, extending along penial caecum with 2-4 stronger pilaster surrounding epiphallic pore. Epiphallus slender, as thick as middle penis, 6.5-8.5 mm in length, internally with 3 major and 1-2 minor pilasters along the entire length. Penis retractor muscle attached at basal 1/6 of epiphallus, becoming narrow distally. Flagellum 6.1-6.7 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

This new species is similar to S. sericata ( Kuroda, 1941) and S. nux ( Möllendorff, 1888) in having a dextral and conical shell with similar sizes ( Figs 3 ; 4 ). Satsuma sericata , however, has a horizontal basal lip with a weak fold ( Fig. 3A ), longer vagina, penis and epiphallus, shorter penial caecum than the new species, and the absence of a penial pouch ( Fig. 3B, C ; Ohara & Otani 2002: pl. 1, figs 14-16). Satsuma nux has a horizontal basal lip and latticed shell base ( Fig. 4A ). The genitalia of S. nux has been dissected in samples collected from four locations ( Wu & Chang 1975). The four locations are distributed from Keelung in northernmost Taiwan to Tunghsu in southwestern Taiwan. The areas are inhabited by at least two other Satsuma species of similar shell shapes, based on the current understanding of Taiwanese Satsuma species ( Hsieh et al. 2013). Because the location of the figured genitalia was not indicated clearly, it is inappropriate to compare directly with the description of Wu & Chang (1975). The newly dissected S. nux in the present study were collected from three locations (loc. # 8-10, Fig. 1 ; Table 1 ) close to its type locality, Taiwanfu (Tainan City nowadays), and have the same shell morphology as the lectotype of S. nux . The genitalia of S. nux ( Fig. 4 B-E) has a shorter penial caecum, a shorter verge extending along penial caecum, a stronger protrusion on the radix of flagellum than the new species, and the absence of a penial pouch. The interior of the epiphallus of S. nux is smooth or has four weak pilasters between the penial caecum and retractor muscle, becoming six strong pilasters when approaching the insertion of the vas deferens. In contrast, the new species has three major pilasters along the entire length of the epiphallus. Sexually mature adults of this new species were collected in July 2021. Four individuals collected in August 2020 have expanded perisomes, but their genitalia are not fully matured.

Figures

FIG. 2. — Shell and reproductive system of Satsuma hsuehshan n. sp.: A, shell of holotype (NMNS-8676-001); B-D, genitalia (paratype NMNS-8676-003), whole genitalia (B), male genitalia showing penial pouch (C), opened genitalia (D). 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.

FIG. 3. — Shell and reproductive system of Satsuma sericata (Kuroda, 1941): A, shell (HCC-15562a); B, whole genitalia (HCC-6921); C, opened genitalia (HCC- 6921). Scale bars: 10 mm. Abbreviations: see Material and methods.

FIG. 4. — Shell and reproductive system of Satsuma nux (MÖllendorff, 1888): A, shell (HCC-1925); B, whole genitalia (HCC-14121a); C, male genitalia showing penial caecum (HCC-1925); D, opened genitalia (HCC-14121a); E, opened male genitalia showing verge (red outlined, HCC-1925). Scale bars: 10 mm, unless otherwise noted. Abbreviations: see Material and methods.

FIG. 1. — Sampling scheme for the snails of genus Satsuma Adams, 1868 used in this study. The numbered sampling sites are detailed in Table 1.