Sinocamaena cheni Wu, 2024

Wu, Min, Chen, Tian & Shen, Wang, 2024, New camaenid genus and species from Zhejiang, East China (Eupulmonata, Helicoidea), ZooKeys 1202, pp. 135-154 : 135-154

Sinocamaena cheni Wu , gen. et sp. nov.

Chinese name.

陈氏中华坚螺.

Type material.

Holotype: a fully mature living snail, HBUMM 08381 - spec. 1, Zhangjiadi [张家地], Yunhe County [云和县], Lishui [丽水], Zhejiang Province; around oaks in remote forest, 27.974 ° N, 119.379 ° E, c. 820 m a. s. l., 2019 - VIII, coll. Chen, Tian [陈天]; molecular voucher specimen HBUMM 08381 a . Paratypes: five fully mature empty shells, HBUMM 08381 - spec. 2 – 6, same collection data as holotype ; HBUMM 08367 , a fully mature living snail; Zhangjiadi, Yunhe County, Lishui , Zhejiang Province; oak woods, coll. Chen, Tian; molecular voucher specimen HBUMM 08367 a- 1 ; HBUMM 08382 - spec. 1, a living snail that reared to maturity at laboratory, same collection data as holotype ; a fully mature empty shell, HBUMM 08370 - spec. 1, Mihougu [猕猴谷], Fengyangshan [凤阳山], Longquan County [龙泉县], Lishui, Zhejiang Province; 27.897 ° N, 119.159 ° E, 1100 m a. s. l., 2019 - VIII- 26, coll. Ye, Shi-Han [叶诗涵] .

Measurement of holotype.

Shell height 19.2 mm, shell breadth 44.3 mm, aperture height 15.9 mm, aperture breadth 22.2 mm, embryonic shell whorls 1 1 / 4, whorls 4 5 / 8.

Description.

Shell (Fig. 1 ) large, depressed. Whorls slightly convex. Suture shallowly impressed. Umbilicus broad with embryonic whorls visible, approximately one-fifth of shell major diameter. Bottom-umbilicus transition changed gently. Columella oblique or obliquely curved. Columellar lip slightly covering umbilicus. Protoconch evenly granulate with strong radial sculpture (Fig. 1 C ). Teleoconch granulate, without hairs, scales or spiral furrows (Fig. 1 D ). Peristome evenly expanded, minutely sinuate. Aperture oblique, slightly expanded. Body whorl large, straight in front, sharply carinate above periphery. Aperture without inner ring-like thickening. Peristome thin, in faint purple. Shell dull and brownish yellow, with many clear thin brown bands above and beneath carina. Measurements (types, N = 8): shell height 17.5–21.0 mm (18.7 ± 1.15 mm), shell breadth 41.2–46.8 mm (43.9 ± 1.89 mm), aperture height 14.2–16.8 mm (15.4 ± 0.86 mm), aperture breadth 20.6–23.8 mm (22.3 ± 1.34 mm), embryonic shell whorls 1–1 1 / 4 (1.125 ± 0.1157 whorls), whorls 4 3 / 8 – 4 5 / 8 (4.531 ± 0.1108 whorls), shell height / breadth ratio 0.41–0.45 (0.43 ± 0.013).

General anatomy (Figs 2 – 4 ). Externally, a small pore present between ommatophore insertions. Eversible head wart surrounding the pore very weakly present. A mantle lobe present. Tentacles and body in dark leaden-black; sole in color lighter than dorsal side. Jaw arcuate; with 12 more or less projecting ribs (Fig. 3 H ). Radula ( HBUMM 08367 - spec. 1) comprises numerous transverse rows of teeth, each row containing approximately 131 teeth, 38 + 27 + 1 + 27 + 38. Central tooth symmetrically conic, without cuspid. Lateral tooth about more than two times larger than central tooth, strong conic medially, weakly uni-cuspid at both sides. Marginal teeth gradually changing from broadly tri-cuspid to tetra-cuspid (Fig. 4 ).

Genitalia (Figs 5 , 6 ). Penial sheath absent. Penis club-shaped, swollen near insertion of penial retractor muscle. Penis externally simple, internally with numerous longitudinal arranged low projections like scales, which do not connect to each other into pilasters along the penial inner wall. Epiphallic papilla rather developed, on side of penial retractor muscle insertion with about several longitudinal pilasters which join apically. Epiphallus very short and stout, internally with a septum longitudinally dividing epiphallus into two separate chambers which one is empty and another one with about 10 pieces of high and low pilasters among which middle one is the strongest (Fig. 6 ). Flagellum absent. Membranous sac surrounding terminal genitalia absent. Dart sac apparatus absent. Vas deferens thin, slightly thickened near epiphallus. Vagina thick, subequal to penis in length. Bursa copulatrix duct thin, proximally not expanded. Measurement in holotype: P – 9.9 mm; Ep – 2.4 mm; VD – 19.4 mm; PR – 4.8 mm; Va – 7.2 mm; FO – 5.4 mm; BC plus BCD – 55.3 mm.

Ecology.

This species was found in the litter layer in broad-leaved forest where oaks dominate (Fig. 8 ). However, the rediscovery of this species failed at one of the known localities (Zhangjiadi, Lishui) in April 2023.

Etymology.

This new species is named in memory of Professor Chen De-Niu [陈德牛 Nov 1939 – March 2024], a known malacologist working on Chinese land molluscs. Prof. Chen was one of the doctoral supervisors for Wu M.

Distribution.

Zhejiang (only from type localities: Yunhe, Longquan).

Remarks.

The new species and Camaena vulpis (Gredler, 1887) are superficially similar in having the densely and minutely granulate surface, numerous spiral thin bands and the general shape of shell. However, besides possessing a distinctly larger shell and a higher spire, the latter species has a totally different genital system, which has a long flagellum ( HBUMM 08664, Liannan [连南], Nature Reserve of Giant Salamander, Guangdong, China, 2023 - VII, coll. Wang Chong-Rui [王崇瑞], Chen Hui [陈辉]). The new species can be promptly distinguished from all the other Chinese camaenid taxa in genitalia because of the absence of the dart sac apparatus and the flagellum.

The phylogenetic analysis suggested that the new species / genus and the taxa distributed in Central China are possibly close relatives (Fig. 7 ). For other comments see the genus.

Figures

Figure 1. Sinocamaena cheni Wu, gen. et sp. nov. A holotype, HBUMM 08381 - spec. 1 B paratype, HBUMM 08382 - spec. 1, reared to maturity in laboratory C, D HBUMM 08381, holotype C shell apex D shell surface. Upper scale for A, B; lower scale for C, D.

Figure 2. Sinocamaena cheni Wu, gen. et sp. nov., paratype, HBUMM 08382 - spec. 1, a specimen reared to maturity in laboratory.

Figure 3. Sinocamaena cheni Wu, gen. et sp. nov., general anatomy A – C holotype, HBUMM 08381 - spec. 1 A lobe-like structure near the anus + pneumostome B mantle lobe on the left margin of mantle collar C anterior part of the animal, dorsal view, between ommatophore tentacles, showing the head gland where the pore / opening is not obvious D – H paratype, HBUMM 08367 - spec. 1 D lobe-like structure near the anus + pneumostome E mantle lobe on the left margin of mantle collar F dorsal view of anterior part of the animal, showing the pore among the contractive head gland G internal body wall of head, showing the head gland pore between the ommatophore tentacles H jaw, with basal muscle tissue remaining.

Figure 4. Sinocamaena cheni Wu, gen. et sp. nov. SEM photos. Paratype, HBUMM 08367 - spec. 1 A section of radula, symmetry axis of radula arrowed B central teeth and lateral teeth; central teeth arrowed C lateral teeth D marginal teeth.

Figure 5. Sinocamaena cheni Wu, gen. et sp. nov., genitalia, holotype, HBUMM 08381 - spec. 1 A general view of genitalia B exposed penis C exposed penial papilla.

Figure 6. Sinocamaena cheni Wu, gen. et sp. nov., holotype, HBUMM 08381 - spec. 1. exposed penis and exposed penial papillae, showing cross-sections.

Figure 7. Maximum-likelihood phylogram based on the concatenated partial mitochondrial 16 S and partial ITS 2 sequences of East Asian camaenid species. The tree is rooted on Helix pomatia. Numbers near nodes indicate the Shimodaira and Hasegawa-approximate likelihood-ratios (SH-aLRT) / approximate Bayes test (aBayes) / ultra-fast bootstrap (IQ-TREE, maximum likelihood) / posterior probability (MrBayes, Bayesian inference). An asterisk on the branch indicates a clade with all well-supported values (SH-aLRT ≥ 80 %, aBayes ≥ 0.95, BS ≥ 95 %, PP ≥ 0.95). The broken branch indicates that the branch is shortened to exactly 1 / 2 the original length. Scale bar is for substitutions per site. Orange branches indicate where the BI tree topologically differs from the ML tree. Red dot / green dot indicates every terminal on that branch that has / has not a mantle lobe. An asterisk after the species name indicates that observation of the mantle lobe failed due to the bad condition of the specimen. The species under the genera in quotes are thought to be questionable generic assignments (Wu et al. 2023).

Figure 8. Habitat of Sinocamaena cheni Wu, gen. et sp. nov., Zhangjiadi, Yunhe County, Lishui.