Satsuma adiriensis, Hwang, Chung-Chi & Wu, Shu-Ping, 2018

Hwang, Chung-Chi & Wu, Shu-Ping, 2018, Two new species of Satsuma A. Adams, 1868 from Taiwan (Pulmonata, Camaenidae), ZooKeys 795, pp. 115-126 : 120-122

Satsuma adiriensis sp. n. Figures 4, 5

Type material.

Holotype NMNS-7945-001, dry shell, coll. C. C. Hwang, 24 Aug 1998, collected from type locality; paratype NMNS-7945-002, 1 specimen: dry shell and dissected soft part in ethanol, coll. S. C. Chang, 4 Jul 1997, Shan-ping, Liu-guei, Kaohsiung, 22°57.93'N; 120°41.28'E, alt. 850 m; paratype NMNS-7945-003, 1 dry shell, coll. C. C. Hwang, 25 May 1998, Mt. Fan-bao-jian, Nan-xi, Tainan, 22°71.48'N; 120°34.4'E, alt. 1000 m; paratype NMNS-7945-004, 1 dry subadult shell, coll. G. S. Hsiang, 29 Jun 1997, Ma-jia, Pingtung, 22°40.07'N; 120°40.65'E, alt. 1200 m.

Type locality.

Taiwan: Pingtung County, Wu-tai, A-li, 22°43.42'N; 120°45.44'E, alt. 1350 m, disturbed primary broad-leaf forest.

Diagnosis.

Shell sinistral, thin, fragile, smooth, with spaced, coarse ridges; periphery round, color band absent; umbilicus completely opened; penial caecum long, internally with elongated verge formed by two main pilasters.

Description.

Shell. Measurements (n = 3): SH 10.8-12.9 mm, SW 17.4-20.6 mm, AH 6.9-8.5 mm, AW 8.6-10.3 mm, W# 5.5, SH/SW 0.61-0.68; sinistral, thin, fragile, semi-translucent, with low conic spire, light brown, without color band. Apex obtuse. Whorls regularly increasing, slightly convex. Periphery bluntly angulated on the first 3/4 of last whorl, becoming rounded 1/4 whorl before peristome. Base of shell convex. Surface covered with loose, coarse, oblique axial ridges, becoming thin on base; spiral striation absent. Aperture roundly lunate. Peristome expanded; outer lip smoothly curved; columellar lip sub-vertical, not reflected, joining with basal lip in a weak angle. Parietal callus smooth, thin, transparent. Umbilicus completely opened, 3.3-3.6 mm in width.

External morphology. Light brown with dense, irregular, dark brown to black spots and a distinct yellowish line running from head between tentacles to collar. Tentacles dark brown.

Reproductive system. Bursa copulatrix oval; pedunculus long, 31 mm in length, with slightly expanded base. Free oviduct short. Vagina thickened, smooth externally, with eleven internal pilasters, 11 mm in length. Atrium obvious, finely wrinkled inside. Penis muscular, 13 mm in length, evenly thickened, furrowed externally; distal half internally supporting three main, finely wrinkled pilasters; proximal half supporting eleven strong, corrugated pilasters. Penial caecum thickened, with blunt apex, protruding 7 mm. Verge extending along penial caecum, formed by two main pilasters. Epiphallus slender, 16 mm in length, internally with three smooth pilasters. Penis retractor muscle attached at distal 1/6 of epiphallus. Flagellum long, tapering, slightly wavy at middle portion.

Etymology.

For Adiri, the indigenous Rukai name of the type locality, adjective of feminine gender.

Distribution.

Known from mid-elevation forest of Kaohsiung, Tainan and Pingtung (Figure 1 E–H).

Ecology.

All specimens were collected in mountainous, mid-elevation, broad-leaf forest. The single live adult was collected in July, from a tree trunk. This species is sym patric with congeneric species S. albida (Adams, 1870) and S. friesiana (Moellendorff, 1884) at Shan-ping, S. amblytropis (Pilsbry, 1901) at Mt. Fan-bao-jian and an unknown Satsuma at the type locality A-li. Despite wide distribution in the mountainous areas of southwestern Taiwan, this species is quite rare.

Remarks.

Satsuma adiriensis sp. n. is similar to S. contraria (Pilsbry & Hirase, 1909), distributed in Kenting, Pingtung, in having a sinistral, semi-transparent shell with completely open umbilicus. The new species, however, has smaller shell width, round periphery on the final 1/4 of the last whorl, a sub-vertical columellar lip, a sinuous upper lip, coarse ridges on the surface, a slender pedunculus of bursa copulatrix, and a longer penial caecum and flagellum and shorter penis than the latter species ( Hwang and Ger 2018).

The new species shares a sinistral and depressed conic shell with Satsuma formosensis (Pfeiffer, 1866) and S. yaeyamensis (Pilsbry, 1894), which are found in northern Taiwan and the Ryukyu Islands. Satsuma adiriensis differs from these two species by its thin, semi-transparent shell with loose, coarse surface ridges, a sub-vertical columellar lip joining basal lip in a weak angle, and a bluntly angulated periphery on the first 3/4 of the last whorl.