Stegodera Martens, 1876

Chen, Zhe-Yu, Lyu, Zhi-Tong & Wu, Min, 2021, Systematic revision of Stegodera Martens, 1876 (Gastropoda, Stylommatophora, Camaenidae), with description of a new genus, ZooKeys 1059, pp. 1-21 : 1

Stegodera Martens, 1876

Helix (Stegodera) Martens in Pfeiffer 1876: 150; Schmacker and Boettger 1894: 173.

Stegodera . - Pilsbry 1905: 64, Yen 1939: 126; Zilch 1960: 610; Schileyko 2003: 1512.

Steganodera Kobelt, 1879: 236 (incorrect subsequent spelling or unjustified emendation); Schileyko 2003: 1512 (syn pro Stegodera Martens, 1876).

Plectopylis (Stegodera) . - Pilsbry 1894: 147.

Planispira (Stegodera) . - Thiele 1931: 681.

Type species.

Helix angusticollis Martens, 1875, by original designation.

Diagnosis.

Shell sinistral. Apical whorls with dense fine ribs that gradually becoming granules. The last 1/4 body whorl compressed, apically covering the contacted penultimate whorl. Peristome expanded and slightly reflexed. Head wart absent. Each side of mantle edge with a leaf-shaped appendage. Penis sheath weakly present. Penis externally simple. Epiphallic papilla absent. Flagellum present. Dart sac apparatus present. Accessory sac well developed. Mucous glands with numerous gland tubes. Membranous sac surrounding terminal genitalia absent. Poly-layered structure in dart sac and/or accessory sac absent.

Remarks.

This genus was considered as a subgenus of Helix Linnaeus, 1758 or Plectopylis Benson, 1860 for some time (Martens 1876; Schmacker and Boettger 1894; Pilsbry 1894). Pilsbry (1905) formally established its independent status. Stegodera and Traumatophora Ancey, 1887 were considered to be closely related, and Traumatophora was once treated as a subgenus of Stegodera ( Pilsbry 1905; Gude 1920). Pilsbry (1905) believed that the two shallow grooves in the throat area of Stegodera are likely to be homologous to the dentition in Traumatophora .

In light of the genital system, Stegodera shares with Nesiohelix the most important character states like the presences of flagellum, numerous tubes of mucous glands and the papilla distally leading to mucous glands on the inner wall of the accessory sac, and the absences of the epiphallic papilla, poly-layered structure in dart sac apparatus and membranous sac surrounding terminal genitalia ( Wu 2019). The close relationship between them in genitalia is supported by the phylogenetic result of this work (Fig. 1A, B ).

Figures

Figure 1. Bayesian Inferences of camaenids (representatives of genera in Table 1) based on partial mitochondrial 16 S and CO 1 sequences. Numbers near nodes indicate Bayesian posterior probabilities. The squares on the right of each taxon name indicate its character states. Abbreviations: PS: penial sheath; EpP: epiphallic papilla; PC: penial caecum; Fl: flagellum; DS: dart sac apparatus A phylogram without Australian camaenids B the results of ancestral states (tagged on branch in red, blue, or black) reconstruction mapping on the phylogram with some Australian camaenid genera added. Orange part: the topologies supported by the results respectively by using both Bayesian Inference and Maximum Likelihood methods. Character states are from Schileyko (2003) and Wu (2019). Scale bars for substitutions per site.