Satsuma auratibasis, Wu & Hwang & Lin, 2008

Wu, Shu-Ping, Hwang, Chung-Chi & Lin, Yao-Sung, 2008, Systematic revision of the arboreal snail Satsuma albida species complex (Mollusca: Camaenidae) with descriptions of 14 new species from Taiwan, Zoological Journal of the Linnean Society 154 (3), pp. 437-493 : 470-471

SATSUMA AURATIBASIS SP. NOV. ( FIGS 25 , 26 )

Material examined

Type specimen: Holotype: TMMT 0609 (from type locality, dry shell, tissue in alcohol). Fifteen paratypes: all from type locality, TMMT 0658 (dry shell, tissue in alcohol, dissected); TMMT 0636–0637 , 0655–0657 (dry shell, tissue in alcohol); NMNS 005405-3 , BMNH 20060760–20060762 , ANSP 413679–413681 , SMF 329388–329389 (dry shell).

Type locality

Mudan, Pingtung County, southern Taiwan ( Fig. 1 , Table 1) .

Diagnosis

Spires and soft body yellowish without pedal stripe; base and sometimes the entire last whorl pale gold; number of whorls more than six; bursa stalk shorter than spermoviduct; base of bursa stalk expanded; principal pilaster long.

Etymology

L. aurat: golden; L. basis: base, referring to its pale golden base.

Description

Shell ( Fig. 25 ): Dextral, conical, thin, fragile, semitranslucent, medium sized. Apex obtuse. Whorls inflated to flat. Periphery roundly curved. Base inflated. Pre-apertural constriction behind peristome absent. Shell colour on upper whorls light yellow; base and sometimes the entire last whorl pale gold, turning white when periostracum peeled away. Shell surface smooth, with fine axial and spiral striae. Aperture diagonal, ovate-lunate to trapezoid. Inferior lip curved; outer lip almost straight. Junction between outer lip and inferior lip curved. Peristome thin, expanded. Columellar lip vertical to subvertical, reflected covering umbilicus. Umbilicus mostly covered by columellar lip, crevice-like. Junction between columellar lip and inferior lip roundly angulated.

Band or stain: This taxon shows polymorphism. Some individuals do not exhibit any colour band or stain whilst others have a red-brown umbilicus and columellar lip; otherwise, the apex, inferior lip and outer lip lack such coloration. Some individuals have a short and thin band immediately behind the insertion of the outer lip. A rare colour pattern exists with the peripheral band and the apical and umbilicus spot. Band formula = 0 0 0 0 0 0 0 0; 1 0 0 0 0 0 7 0; 1 0 0 4 0 0 7 0 (rare).

Reproductive system ( Fig. 26 ): The genital morphology is highly similar to that of S. mollicula and can be distinguished by (1) the longer bursa stalk of S. auratibasis , which is three-fifths the length of the spermoviduct, than that of S. mollicula ; and (2) the longer epiphallus of S. auratibasis , which has a length almost equivalent to the penis. The length of epiphallus in S. mollicula is three-fifths that of the penis.

Distribution

This species is distributed in lowland (<400 m) broadleaf forest habitats around the north end of Hengchun peninsula, Pingtung County, southern Taiwan, including Mudan , Shuangliu and Shouka ( Fig. 1 , Table 1) .

Remarks

The animals were found from 2 m above ground to the tree canopy. Adults were found in spring and usually perched higher than juveniles ( Fig. 25I ).

Satsuma auratibasis sp. nov. is similar to S. mollicula based on the morphological characters of shell and genitalia. Both were found distributed on Hengchun peninsula, southern Taiwan, but their distributions do not overlap. The former species is distributed in the northern part of the area, the latter in the south ( Fig. 1 ). Furthermore, molecular phylogeny indicates S. auratibasis is close to S. huberi rather than S. mollicula despite the morphological similarities. Satsuma auratibasis differs from S. mollicula in that its shell is larger, angulated at the periphery that is never keeled, pale gold in colour, never greenish gold as seen in S. mollicula . Moreover, the golden tint is confined to the base or the last whorl only of S. auratibasis . S. auratibasis differs morphologically from S. huberi in having gold-tinted shell base, conical base of bursa stalk, long bursa stalk and long principal pilaster.

Figures

Figure 1. Sampling localities of all taxa in Taiwan. Bold line, Central Range; thin line, administrative boundary.

Figure 25. Satsuma auratibasis sp. nov. A–D, holotype (TMMT 0609, shell height = 20.1 mm). E, F, paratype (TMMT 0636, shell height = 20.8 mm). G, H, paratype (TMMT 0637, shell height = 18.4 mm). I, living specimen.

Figure 26. Reproductive system of Satsuma auratibasis sp. nov. (paratype, TMMT 0658). A, whole genitalia; B, interior of genitalia. Scale bar = 5 mm. See text for abbreviations.