Ponsadenia (Ponsadenia) zhongdianensis, Wu, Min & Guo, Jian-Ying, 2006

Wu, Min & Guo, Jian-Ying, 2006, Revision of the Chinese species of Ponsadenia (Gastropoda: Helicoidea, Bradybaenidae), Zootaxa 1316, pp. 57-68 : 63-66

Ponsadenia (Ponsadenia) zhongdianensis sp. nov.

Figs. 4 A–D, 5A–G; Tab. 1

Type material. Holotype: HBUMM 01790­specimen 1; paratypes: HBUMM 01790­ specimen 2–31. Fully mature shells in ethanol.

Type locality: China: Yunnan Province: Zhongdian County: near Jiantang, Songzanlin Lama Temple, 3220 meters above sea level, (N 27° 51' 36.3'', E 099° 42' 01.2''), limestone and brown earth, scrubland. 3nd July, 2002. Coll. A. Wiktor and M. Wu.

Etymology. The new species is named after the type locality “Zhongdian”.

Diagnosis. Accessory sac with one mucous gland, bridge­like, fused to vagina by thin membrane rather than thick connective tissue. Penial sheath very short.

Shell. Distinctly flattened, height to width ratio 0.49–0.68 (mean 0.61) ( Fig. 4 C, Tab. 1 ); thin but solid; dextral. Whorls convex. Suture impressed. Umbilicus narrow. Columella oblique. Columellar lip slighted dilated, not covering umbilicus. Spiral furrows regularly, densely distributed. Shell surface ribless. Growth lines distinct; not accompanied with irregular thickenings. Young shell rough with continuous scales along growthlines; adult shell smooth, periostracum worn away. Protoconch densely, finely granulose, in full grown shells usually worn smooth, shiny. Teleoconch not granulose. Young shell angulated above periphery. Adult body whorl bluntly angulated above periphery; slightly descending; underside convex. Aperture roundly triangular; oblique. Aperture with two extremely flat palatal teeth, no parietal tooth; evenly expanded. Peristome thin, slightly reflexed. Callus indistinct. Shell yellowish brown; dull; with one indistinct paler peripheral band ( Figs. 4 A–D). Shell measurements: see Table 1 .

Soft parts creamy white with sparsely distributed dark spots. Jaw arcuate with three ribs in holotype ( Fig. 5 D) (five ribs in paratype HBMM 01790­specimen 2).

Genitalia. Membranous sac surrounding terminal genitalia absent. Penial sheath short, about 1/5 penis length. Penis about twice as long as dart sac; slender; simple outside ( Fig. 5 A). Penial pilasters similar, undifferentiated. Penis­epiphallus chamber absent. Epiphallic papilla absent. Flagellum absent ( Fig. 5 C). Vas deferens slightly thickened near penial retractor. Single mucous gland; approximately equal to dart sac in length; with distinct peduncles; complicatedly branched ( Figs. 5 A, B). Vaginal region short between dart sac and atrium. Proximal part of dart sac without neck­structure. Dart sac containing one dart. Dart ca. 2.5 mm in length (in holotype); slightly curved; basally expanded; apical 1/3 twobladed ( Figs. 5 E, F). Accessory sac bridge­like, open toward atrium opening, inserted in bottom of, distinctly visible from outside of dart sac; fused to vagina by thin membranous wall; with internal pilasters undifferentiated. Inside accessory sac, papilla of mucous gland entrance present but simple without derived structure. Polylayered structure absent ( Fig. 5 F).

Measurements of genitalia (holotype): Dart sac 6.0 mm long; 1.0 mm wide. Mucous glands 5.0 mm; vagina 11.0 mm; bursa copulatrix and its duct 11.5 mm; vas deferens 20.5 mm; penis 11.5 mm; penial retractor 1.3 mm.

Distribution. Only known from the type locality.

Ecological remarks. This species is found only within a very limited range with an area of approximately 100× 500 m 2. The location is a small isolated limestone hill surrounded by farmland. The habitat is composed of calcareous rocks, scrubs and grass. The snails were found near the roots of plants or hidden in crevices of rocks.

Remarks. The new species more or less resembles P. (P.) semenovi in the structure of its reproductive apparatus. However, the occurrence of the single mucous gland, very short penial sheath, the bridge­like accessory sac which is fused to vagina by thin membrane, and the shell morphology (comparison to other species: see Table 2 ), distinguish it from all other Ponsadenia species.

Figures

FIGURE 4. Ponsadenia (Ponsadenia) zhongdianensis sp. nov., Holotype, HBUMM 01790 ­ specimen 1. A, apical view; B, umbilical view; C, apertural view; D, oblique apertural view, showing the shape of aperture.

FIGURE 5. Ponsadenia (Ponsadenia) zhongdianensis sp. nov. A, general view of genitalia; B, another side of dart apparatus, opposite to A; C, inside view of penis chamber; D, jaw; E, dart with cross­sections; F, sagittal section of dart apparatus, with cross­sections; G, ovotestis. A, D, G, paratype, HBUMM 01790 ­ specimen 2; B, C, E, F, paratype, HBUMM 01790 ­ specimen 3.

Tables

TABLE 1. Descriptive statistics of the holotype and paratypes (31 specimens in total) of Ponsadenia zhongdianensis sp. nov. (measurements in millimeter).

Holotype	Minimum	Maximum	Mean	Std. deviation
Height 7.6	5.3	8.4	7.02	0.55
Diameter 12.2	10.4	12.8	11.51	0.57
Whorls 5 1/4	4 5/8	5 1/4	4.911	0.171
Protoconch whorls 1 1/2	1 1/4	1 3/4	1.536	0.098
Al 6.0	5.0	6.4	5.72	0.38
Aw 5.6	4.3	5.9	5.20	0.37
Umbilicus diameter 2.0	1.6	2.4	1.99	0.20
Ratio of height/diameter 0.63	0.49	0.68	0.61	0.04
Ratio of umbilicus diameter/ diameter 0.16	0.15	0.21	0.17	0.02

TABLE 2. Comparison of shell morphology among Ponsadenia species (Egorov & Ivanov 1997; this study) (measurements in millimeter).

	Height	Diameter	Whorl number
P. (P.) dentata (Rymzhanov, 1983)	4.5	6.5	5–5.25
P. (P.) semenovi	9	14.5	5–5.5
P. (M.) duplocincta	26	27	6–6.5
P. (T.) hirsuta	5	10.8	4.5–6
P. (P.) zhondianensis sp. nov.	5.3–8.4	10.4–12.8	4 5/8–5 1/4