Monday, September 21, 2015

[Mollusca • 2014] Aegista diversifamilia • Taxonomic Revision of Aegista subchinensis (Möllendorff, 1884) (Stylommatophora, Bradybaenidae) and A Description of A New Species of Aegista from eastern Taiwan based on Multilocus Phylogeny and Comparative Morphology

Figure 8. Living snail Aegista diversifamilia sp. n. from Heren, Xiulin Township, Hualien County, Taiwan

Aegista subchinensis (Möllendorff, 1884) is a widely distributed land snail species with morphological variation and endemic to Taiwan. Three genetic markers (partial sequence of the mitochondrial cytochrome c oxidase subunit I [COI], the 16S rDNA and the nuclear internal transcribed spacer 2 [ITS2]) were analysed to infer phylogenetic relationships and genetic divergence of closely related species of the genus Aegista, A. vermis (Reeve, 1852) and A. oculus (Pfeiffer, 1850). A new species from A. subchinensis has been recognized on the basis of phylogenetic and morphological evidences. The nominal new species, Aegista diversifamilia sp. n. is distinguished from A. subchinensis (Möllendorff, 1884) by its larger shell size, aperture and apex angle; wider umbilicus and flatter shell shape. The northernmost distribution of A. diversifamilia sp. n. is limited by the Lanyang River, which is presumed to mark the geographic barrier between A. diversifamilia sp. n. and A. subchinensis.

Keywords: Stylommatophora, Helicoidea, Southern Ryukyu Islands, Yaeyama Islands, new species


Superfamily Helicoidea Rafinesque, 1815
Family Bradybaenidae Pilsbry, 1939

Genus Aegista Albers, 1850
Type species: Helix chinensis Philippi, 1845, original designation.

Aegista diversifamilia sp. n.

Figures 7, 8, Table 4, Suppl. material 1, Table S1
Aegista subchinensis Hsieh, 2003: 200, figs; Lee and Chen 2003: 234, figs above text, figs 1–2; Lee and Wu 2004: 13–14, figures 2A, 3D; Hsieh et al. 2006: 250, figs; Wu and Jian 2006: fig 33; Hsieh et al. 2013: 335, figs.
Aegista (Aegista) subchinensis Hemmen and Niederhöfer, 2007: figs 67, figs 80; Wen and Hwang 2014: fig 1.

Etymology: Named after the recent efforts supporting equal marriage rights in Taiwan and around the world. Derived from “diversus” (Latin for different) and “familia” (Latin for family), adjective of feminine gender.

Distribution: Endemic to Taiwan and is currently known from I-Lan and Hualian Counties. Aegista diversifamilia sp. n. is absent from Gueishan Island based on our field investigation (Huang et al. 2013). The northernmost distribution is limted by the Lanyang River. We suggest that the Lanyang River is the putative biogeographic boundary between A. diversifamilia sp. n. and A. subchinensis.

Ecology: Live snails are generally found on the ground or under leaf litter in shady, moist environments in lowland hardwood forests (Figure 8). Eggs white and round, approximately 3 mm in diameter with 20–30 eggs in each spawn (personal observation of reared snail in laboratory).

 Huang, Chih-Wei; Lee, Yen-Chen; Lin, Si-Min; and Wu, Wen-Lung. 2014. Taxonomic Revision of Aegista subchinensis (Möllendorff, 1884) (Stylommatophora, Bradybaenidae) and A Description of A New Species of Aegista from eastern Taiwan based on Multilocus Phylogeny and Comparative Morphology. ZooKeys. 445: 31–55. doi: 10.3897/zookeys.445.7778.