Trichocathaica vestita (Pilsbry, 1934) Pilsbry, 1934

Pall-Gergely, Barna, unyadi, Andras & Asami, Takahiro, 2018, Enantiomorphs and taxonomy of three conchological species in flat-shelled snails Trichocathaica (Pulmonata, Camaenidae), ZooKeys 810, pp. 19-44 : 25-27

Trichocathaica vestita (Pilsbry, 1934) comb. n. Figures 4A, 5, 6, 7, 8

Cathaica constantinae vestita Pilsbry, 1934: 15, plate 3, figs 5-7.

Types examined.

Between Wenchwan and Weichow, June, 1931, ANSP 159708 (photos of the holotype were examined).

Additional material examined.

2015/64 Sichuan, Ganzi Zhou, Kangding Xian, Wasihekou, southern side of the river, along the highway, 1420 m a.s.l., 30°04.564'N 102°09.865'E, leg. A. Hunyadi, 14.06.2015, HNHM 103470 (dextral shell, Fig. 5 D–F + ethanol-preserved body: Figs 6A, 7A, 8A), HA/15 dextral shells, PGB/3 dextral shells; 2015/65 China, Sichuan, Ganzi Zhou, Kangding Xian, Wasihekou 200 m towards Guzan Zhen, around the stupa, 1420 m a.s.l., 30°04.565'N, 102°10.085'E, leg. Hunyadi, A. & Szekeres, M., 14.06.2015, HNHM 103471 (1 sinistral shell, Fig. 5 A–C + ethanol-preserved body: Figs 6 B–C, 7B, 8B), HA/6 sinistral shells + 2 dextral shells, PGB/3 sinistral shells; W-Sytschuan, Wa-sy-Kou am Tung, coll. Möllendorff ex coll. Potanin, SMF 8940 (1 dextral shell, paralectotype of amphidroma ); China, W-Sytschuan: Wa-sy-Kou am Tung, coll. O. Möllendorff ex coll. Potanin, SMF 349506 (1 dextral shell, paralectotype of amphidroma , ex SMF 8941); Sy-tschuan, rechter Ufer des Flusses Tun bei dem Torfe (?) Wa-sy-ku, coll. O. Möllendorff ex coll. Potanin 3898a, 1903, SMF 95002 (1 dextral shell, paralectotype of amphidroma ); W-Sy-tschuan, coll. Möllendorff, SMF 349505 (1 dextral shell, paralectotype of amphidroma , ex SMF 9171); W-Sytschuan, Liu-Ting am Tung, coll. Möllendorff ex coll. Potanin, SMF 349503 (2 dextral shells, paralectotypes of amphidroma , ex SMF 8938); W-Ufer d. Lu Ho (Ta Tu Ho) zw. Tapien und Ja sz’kou, ex Krejci-Graf, 05.08.1930, SMF 349507 (2 dextral shells, ex SMF 24667).

Diagnosis.

Shell sinistral or dextral, body whorl rounded to keeled, teleoconch finely wrinkled with small scale-like periostracal folds; fold scars (if visible) represented as short curved lines.

Description.

Shell sinistral or dextral, spire slightly elevated; body whorl rounded (with a very slight indication of a keel) to keeled, protoconch consists of 1.25-1.5 whorls, finely, irregularly wrinkled; entire shell with 5.25-5.75 whorls; teleoconch finely, irregularly wrinkled, with small, low, dense periostracal folds having curved (C-shaped) base; scales not visible to the naked eye; in specimens/shell parts without periostracum the bases of folds or sometimes not visible as small curved lines; aperture subcircular, peristome slightly expanded, thin, sharp; inner, white thickening parallel to the peristome prominent, situated in some distance from peristome edge.

Measurements (in mm).

D = 21.2-23.6, H = 11.1-13.6 (n = 12).

Anatomy

(Figs 6, 7). Genital morphology of two specimens (HNHM 103470, dextral specimen and HNHM 103471, sinistral specimen) showed that the left ommatophoral retractor crosses between penis and vagina in the sinistral specimen, and that the right retractor in the dextral specimen. Atrium short, penis with a slimmer, shorter distal, and a thicker, longer proximal portion, distal portion covered by a weak penial sheath; epiphallus much more slender than penis, approximately as long as penis; retractor muscle shorter in sinistral and longer in dextral specimen, inserts on epiphallus, close to its meeting point with penis; proximal part of penis internally with reticulated zigzag sculpture caused by the perpendicular projections of longitudinal folds (Fig. 8); dart sac well developed, with thickened, larger basal part and smaller head part; dart was only found in the dextral specimen (Fig. 7); long glandulae insert on 4-6 points on the “neck” of the dart sac (at the meeting point of the body and head of the dart sac) (Fig. 6C); vagina short in dextral and longer in sinistral specimen, stalk of bursa copulatrix long, relatively slender, bursa ovoid, diverticulum absent; spermoviduct slender, no embryos found; albumen gland crescent shaped, talon relatively large.

We found no discrete differences between the dextral and sinistral individuals in gross anatomy of the genital system or in the internal structure of the dart sac (Figs 6, 7). The internal surface of the penial tube exhibited complex patterns of microsculpture typical to camaenid snails (Fig. 8). In this structure, several slight differences were noticeable between these specimens of enantiomorphs. Around the area leading to the epiphallus (upper edge in Fig. 8), thin longitudinal pilasters are more tightly gathered with narrower furrows in the dextral than in the sinistral. In both of them, toward the middle of the penial tube, these pilasters become thick and sparse with wider furrows and form a reticulate pattern. Longitudinally (in the direction towards the genital orifice, the bottom in Fig. 8) under the reticulated range, zigzag crenulated pilasters are present in parallel. In these portions, structural change from the reticulate pattern to the parallel pilasters is more distinct in the dextral than in the sinistral. Smooth-bottomed furrows separate the zigzag pilasters in the dextral, whereas those furrows are not obviously present between the irregularly zigzag-shaped pilasters in the sinistral. This structure of the dextral is present in a longitudinally wider range than the sinistral. In the sinistral, instead, the irregular zigzag structure becomes weak or disappears from the longitudinal pilasters, which become thick and pronounced near the genital orifice. This longitudinal structural change is not present in the dextral. The dextral instead exhibits a different pattern such that the longitudinally parallel zigzag pilasters are continuously present and merge with one another without forming major pilasters.

Differential diagnosis.

Trichocathaica vestita differs from T. macrosquamata sp. n. by having the smaller periostracal folds (scales) on the entire shell surface.

Distribution.

This species is known from the valley of the Dadu River at Luding and Wasigou.

Remarks.

This species was described as a subspecies of Helix (Camaena) constantinae Adams, 1870. We had no possibility to examine that species; however, it has remarkably different shell traits, such as the strongly sculptured shell surface and a white band (see Fig. 4B). That species is probably not a Trichocathaica , but something entirely different, as Pilsbry (1934) already suspected. Moreover, Trichocathaica seems to inhabit only the mountains in Sichuan and southern Gansu, and Helix (Camaena) constantinae was collected in the "Ichang gorge" on the Yangtze River in Hubei Province (ca 30°55'N, 110°50'E, Adams 1870). Therefore, we handle Trichocathaica vestita (Pilsbry, 1934) as a species of its own right.

Pilsbry (1934) already noted in the original description that the species show an extreme variability in terms of the development of the keel. Our data also indicates that the keel morphology is variable within and between populations. In the sample of 2015/64, 15 shells had nearly rounded body whorls, two were keeled, and two were intermediate between those rounded and keeled forms. Although every shell in the sample of 2015/65 had a keel, two of them were similar to the intermediate form of the 2015/64 sample.