Sinocamaena 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 Wu gen. nov.

Chinese name.

中华坚螺属.

Type species.

Sinocamaena cheni Wu , gen. et sp. nov.

Diagnosis.

Shell depressed. Protoconch and teleoconch granulate. Protoconch strongly sculptured. Peristome expanded. Head wart low and tiny. Between the ommatophore insertions, a gland pore present. A mantle lobe present. Penial sheath absent. Epiphallus very short. Epiphallic papilla well developed. Flagellum absent.

Description.

Shell depressed. Whorls slightly convex. Suture slightly impressed. Umbilicus broad. Protoconch with granules on strong radial sculpture. Peristome expanded. Adult shell surface without ribs, hairs or scales. Growth lines fine and evenly broken into granules on teleoconch. Shell with several thin bands above and beneath carina.

General anatomy. A small pore externally present between ommatophore insertions. Eversible head wart very weakly developed. A mantle lobe present.

Genitalia. Penial sheath absent. Penis externally without penial caecum. Pilasters inside penis low and weak. Epiphallus very short. Epiphallic papilla rather developed. Flagellum absent.

Etymology.

This new genus is named after “ sino ” (= China) and “ camaena ” which is a camaenid genus that includes many large-sized helicoid species.

Distribution.

China: Zhejiang.

Remarks.

The new genus is conchologically close to many camaenids, such as Camaena Albers, 1850 and Burmochloritis Godwin-Austen, 1920 , in having a large helicoid shell with multiple slender bands. In comparison to Camaena (sensu Schileyko 2003), the new genus has a strongly sculptured protoconch and an extremely short epiphallus (the part between penial retractor muscle insertion and vas deferens insertion), but has neither the axial corrugated pilasters within penis nor the flagellum. The new genus differs from Burmochloritis ( Páll-Gergely et al. 2023) in the absence of the flagellum, the long cylindrical epiphallus, the penial caecum and the dart sac. Sinocamaena gen. nov. shares with Sinochloritis the possession of granules on the protoconch and the characters from both general and genital anatomy, including the presence of a visible gland pore between the ommatophore insertions, a mantle lobe, a well-developed epiphallic papilla and the absence of a penial sheath and a dart sac apparatus. Compared to Sinochloritis , the new taxon has neither a flagellum nor a long epiphallus with the cylindrical trunk, nor prominent penial pilasters. In terms of shell morphology, generally, the new genus looks different from any other Chinese indigenous camaenid genus. Regardless of the shell morphology, all the other Chinese camaenid genera having no dart sac apparatus, i. e., Amphidromus Albers, 1850 , Landouria Godwin-Austen, 1918 , Pancala Kuroda & Habe, 1949 , Satsuma , Yakuchloritis Habe, 1955 , Pseudostegodera and the above mentioned Sinochloritis , possess a well-developed flagellum in the male part of genitalia (table 1 in Wu 2023). The present phylogeny (Fig. 7 ) suggests that the new taxon is possibly the nearest relative of almost all the members of dart sac-bearing bradybaenines endemic to the South Gansu Plateau or Central China.

It is noteworthy that the taxa that are basal on the phylogram, i. e., Nesiohelix , Traumatophora , Acusta , Bradybaena , Plectotropis , Aegista , Euhadra , Satsuma , Camaena , have mantle lobes. In general, the camaenids from Central China constitute a monophyly that receives high support values (clade X in Fig. 7 ), in which all terminals have a dart sac apparatus but lack a mantle lobe. The extended study of mantle lobes in helicoids taken here suggests that the presence of the mantle lobe could be a widely distributed and possibly a plesiomorphic character in the superfamily Helicoidea .

Figures

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).