Research Article |
Corresponding author: Min Wu ( minwu1969@aliyun.com ) Academic editor: Edmund Gittenberger
© 2019 Min Wu, Zhengping Liu.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Wu M, Liu Z (2019) The first proven oxychilid land snail endemic to China (Eupulmonata, Gastrodontoidea). ZooKeys 870: 33-50. https://doi.org/10.3897/zookeys.870.32903
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A new and the first proven oxychilid species endemic to China is reported from Sichuan Province. Sinoxychilus gen. nov. is established based on this new species and has diagnostic traits of the sculptured protoconch, partial epiphallus wrapped by developed penis sheath, penial retractor muscle inserting on the top of penial caecum, spinelets on penial pilasters, absence of epiphallic papilla and perivaginal gland present on vagina and proximal bursa copulatrix duct. In light of shell morphology and through geometric morphometric analyses, Zonites scrobiculatus scrobiculatus Gredler and Z. scrobiculatus hupeina Gredler are proposed to be included in the new genus. A phylogenetic inference based on ITS2 gene indicates that the new genus is systematically close to Oxychilus Fitzinger, which is known from the Western Palearctic and the Southwestern Arabian Peninsula, regions that are geographically far from the distribution range of the new genus.
首次从四川青城山报道了璃螺科(Oxychilidae,癞蜗牛总科Gastrodontoidea)的陆生软体动物。依据胚螺具雕饰、交接器鞘包裹部分成荚器、交接器收缩肌着生于交接器盲囊顶端、交接器内的壁柱具小棘、成荚器乳突阙如、雌道及纳精囊管基部具雌道周腺等特征,建立了由貊华璃螺Sinoxychilus melanoleucus gen. nov. and sp. nov.为属模式种的华璃螺属Sinoxychilus gen. nov.。根据贝壳特征及贝壳几何形态学分析,认为分别分布于湖南和湖北的Zonites scrobiculatus scrobiculatus Gredler, 1885 与Z. scrobiculatus hupeina Gredler, 1887当归于本新属。据ITS2序列重建的支序关系揭示该属与广泛分布于古北区西部等地区的璃螺属(Oxychilus Fitzinger)具有较其它癞蜗牛总科类群更近的系统发生关系。地理分布上,华璃螺为位于璃螺科连续分布区之外的一属。
Geometric morphometric analysis, ITS2, new genus, Oxychilidae, phylogeny, Sichuan
The family Oxychilidae Hesse, 1927 is one of the three families under the superfamily Gastrodontoidea Tryon, 1866 (sensu
Gredler (1881) proposed H. (Conulus) franciscana Gredler, 1881 and its subspecies H. (Conulus) franciscana planula Gredler, 1881 (Futschiazung, Hunan) (
Gredler (1885) proposed H. crystallodes Gredler, 1885. In the second series of the “Manual of Conconchology”,
Then, Gredler transferred H. franciscana, H. franciscana planula Gredler (not Heude, 1882), and H. spiriplana to Kaliella and transfered H. rathouisii to Nanina; while retaining H. politissima, H. planula Heude, H. zikaveiensis, and H. loana in Hyalina (
None of the above mentioned species was anatomically examined. Over-dependence on shell morphology caused many conflicts in the early classification of Chinese species of Hyalina. Furthermore, none of the above-mentioned species that had once been treated as Hyalina has been studied since
Four living animals and three empty shells, all fully mature, were collected by hand from the type locality. The living specimens were relaxed by drowning in water before being transferred to 70% ethanol which was replaced with ethanol of the same concentration after three days. The sizes of shell and genitalia of each specimen were measured with calibrated digital Vernier callipers and from photos, both to the nearest 0.1 mm. The number of whorls was recorded with 0.125 whorl accuracy as described by
Whole genomic DNA was extracted from a piece of pedal muscle of the ethanol-preserved specimens using Animal Genome Quick Extraction Kit (B518221, Sangon Biotech). Each 25 μL PCR mixture consisted of 12.5 μL cwbio 2× Es Taq MasterMix Dye, 9.5 μL ddH2O, 1 μL template DNA, 1 μL forward primer (10μL/L) (5′-CTAGCTGCGAGAATTAATGTGA-3′,
Chromatographs and sequences were examined and were initially compiled in Sequencher 4.5. The sequence alignment, the evolution model selection and the Maximum Likelihood inference were performed by MEGA 7.0.26 (
Shell morphological variation study was performed in the tps series software including tpsUtil32 (
Directions used in descriptions: proximal = towards the genital atrium; distal = away from the genital atrium.
Abbreviations: At – atrium; BC – bursa copulatrix; BCD – bursa copulatrix duct; Ep – epiphallus; fma – fully mature animal(s); FO – free oviduct; HBUMM – Mollusc collection of the Museum of Hebei University, Baoding, China; OE – orifice of epiphallus; P – penis; PC – penial caecum (this part is judged here as penial caecum rather than flagellum as termed in some works because the flagellum, if present, is located at the distal end of epiphallus); PP – penial pilaster; PR – penial retractor muscle; PS – penis sheath; PVG – perivaginal gland; Va – vagina; VD – vas deferens.
Sinoxychilus melanoleucus gen. nov. and sp. nov.
Protoconch with intercrossing radial wrinkles and spiral grooves. Penis sheath developed, more or less wrapping partial epiphallus. Tubercles of broken longitudinal penial pilasters bearing spinelets. Penial retractor muscle inserting on the top of penial caecum. Neither flagellum nor epiphallic papilla present. Perivaginal gland present on vagina and proximal bursa copulatrix duct.
Shell depressed; thin; opaque; of about 4.5 whorls. Umbilicus moderately wide. Protoconch with intercrossing radial wrinkles and spiral grooves. Teleoconch with spiral furrows. Aperture somewhat sinuate at peristome. Aperture toothless, unexpanded.
Sole tripartite. Caudal foss or caudal horn absent. Jaw oxygnathous, with median projection.
Penis sheath present; wrapping partial epiphallus. Penis moderately long and thick; externally simple. Sarcobelum absent. Penial caecum present, having no external demarcation between it and penis. Penial retractor muscle inserting on top of penial caecum. Flagellum absent. Epiphallus thin. Penial caecum internally with transversal ridges near epiphallic pore. Epiphallic papilla absent. Penis internally with developed pilasters. Penial pilasters broken into connected tubercles that each bearing a very short spinelet. Vagina short, internally simple, and without papilla or verge. Perivaginal gland well developed on the surface of vagina and proximal part of bursa copulatrix duct.
China (Sichuan, Hunan, Hubei).
The generic name is a compound of Greek “sino” (= China) and Oxychilus which is a genus of the family Oxychilidae.
The examined ITS2 sequences are from GenBank and this study. According to
Family | Species | Genbank Accession No. of ITS2 |
Euconulidae | Euconulus alderi (J.E. Gray, 1840) | MK299689, MK299710 |
E. chersinus (Say, 1821) | MK299741 | |
E. dentatus (Sterki, 1893) | MK299732, MK299739 | |
E. fulvus (O.F. Müller, 1774) | MK299691, MK299693, MK299695, MK299702, MK299723, MK299724, MK299737, MK299738 | |
E. trochulus (Reinhardt, 1883) | MK299730–31 | |
E. polygyratus (Pilsbry, 1899) | MK299747 | |
Pristilomatidae | Vitrea crystalline (O.F. Müller, 1774) | AY014113 |
Oxychilidae | Oxychilus alliarius (Miller, 1822) | JF837183, AY014114 |
O. cellarius (O.F. Müller, 1774) | AY014116 | |
O. helveticus (Blum, 1881) | AY014115 | |
Sinoxychilus melanoleucus gen. nov. & sp. nov. | MN056416, MN056417 | |
Camaenidae (Outgroup) | Pseudiberus liuae Wu, 2017 | MN056414, MN056415 |
Morphologically, this group belongs to the family Oxychilidae based on the presence of a tripartite sole, oxygnathous jaw, penis sheath, and perivaginal gland and the absence of a caudal horn and sarcobelum, by which Sinoxychilus gen. nov. can be promptly distinguished from Gastrodontidae and Pristilomatidae, the other two families of Gastrodontoidea (sensu
Zonites scrobiculatus scrobiculatus Gredler, 1885 and Z. scrobiculatus hupeina Gredler, 1887 are included in the new genus although they are only known conchologically (see Taxonomic remarks below).
Riedeliconcha Schileyko, 2003 and Vitrinoxychilus Riedel, 1963 are two oxychilid genera which also have spines on the penis inner wall. The new genus differs from them in possessing well-developed penial caecum, penis sheath, and epiphallus, a long bursa copulatrix, and conchologically, an opaque shells with a sculptured protoconch.
Holotype, 1 fma (HBUMM08236 specimen-1), Qingchengshan Mt., humid forest, in litter (Fig.
Shell (Figs
General anatomy. Sole tripartite. Caudal foss or caudal horn absent. Eversible head wart between ommatophore insertions absent. Tentacles and dorsum leaden-black. After preservation in 70% ethanol, black pigments on animal become faint. Lower sides and sole creamy white (Figs
Genitalia (Figs
Sinoxychilus melanoleucus gen. nov. and sp. nov., holotype, HBUMM08236 specimen 1 A partial soft part B partial jaw. Dotted line indicating axis line C genitalia in general view. At-atrium; BC-bursa copulatrix; BCD-bursa copulatrix duct; Ep-epiphallus; P-penis; PC-penial caecum; PR-penial retractor muscle; PS-penis sheath; PVG-perivaginal gland; Va-vagina; VD-vas deferens.
Sinoxychilus melanoleucus gen. nov. and sp. nov. A Genitalia in general view, paratype, HBUMM08236 specimen 2, showing the median section of epiphallus is not wrapped inside the penis sheath B, C holotype, HBUMM08236 specimen 1 B interior view of penis C a section of magnified penial pilaster, showing apical spinelet on each tubercle consisting the penial pilaster. At-atrium; BCD-bursa copulatrix duct; Ep-epiphallus; FO-free oviduct; OE-orifice of epiphallus; P-penis; PC-penial caecum; PP-penial pilaster; PR-penial retractor muscle; PS-penis sheath; PVG-perivaginal gland; Va-vagina; VD-vas deferens.
Sinoxychilus melanoleucus gen. nov. and sp. nov., HBUMM08236 specimen 2, paratype A–C indicating that the median part of epiphallus was dissecting out from the penis sheath C arrow indicates epiphallus insertion. Ep-epiphallus; P-penis; PC-penial caecum; PR-penial retractor muscle; PS-penis sheath; VD-vas deferens.
The new species is known only from its type locality.
The species is named for the clear demarcation between the leaden black ommatophores and dorsum and the remaining creamy white body, which is reminescent of the giant panda, Ailuropoda melanoleuca by having the color pattern of clear-cut patches of black and white (Fig.
The new species was found living in extremely humid environment at type locality. In the laboratory, below 100% relative humidity, animals became active at the relatively lower temperature of 5 °C (Fig.
This new species can be distinguished from all other Chinese Hyalina species in the measurements of its shells (Table
Shell measurements and distribution of Chinese species once grouped in Hyalina A. Férussac, 1821, with synonyms excluded.
Species | Whorls | Diam. maj. (mm) | Height (mm) | Distribution |
Hyalina fulva O.F. Müller, 1774 | 5–6 | 4 | 3.5* | Beijing, E Mongolia |
H. politissima (L. Pfeiffer, 1853) | 4.5 | 24 | 11 | Sri Lanka, NE China |
H. rejecta (L. Pfeiffer, 1859) | 6 | 3.5 | 3 | Hunan, Guangdong, NE China |
H. superlita (Morelet, 1862) | 5–5.5 | 16.5–21 | 10–11.5 | Guangdong, Macao |
H. perdita (Deshayes, 1874) | 4 | 3 | 1.5* | Beijing, E Mongolia |
H. moellendorffi (Reinhardt, 1877) | 5.5 | 10 | 5.5 | Beijing |
H. (Conulus) franciscana Gredler, 1881 | 6 | 3.5 | 3 | Hunan |
H. (Conulus) f. planula Gredler, 1881 | 6 | 3.5 | 2 | Hunan |
H. (Conulus) spiriplana Gredler, 1882 | 4.5–5 | 3 | 13/4 | Hunan |
H. (Zonitoides?) loana Gredler, 1882 | 5 | 43/4–5 | 2 | Hunan |
H. bambusicola Heude, 1882 | 5 | 3.5–4 | 3.5 | Anhui |
H. castaneola Heude, 1882 | 6 | 3–4 | 3 | Anhui |
H. colombeliana Heude, 1882 | 6 | 4.5–5 | 3.5 | Jiangsu |
H. gredleriana Heude, 1882 | 6 | 2.5–3 | 3.5 | Hunan |
H. imbellis Heude, 1882 | 5.5 | 3.5–33/4 | 3 | Anhui |
H. planula Heude, 1882 | 4.5 | 6–7 | 3 | Anhui |
H. planata Heude, 1882 | 4 | 9–10 | 3.5 | Hunan |
H. rathouisii Heude, 1882 | 7 | 6 | 3.5 | Shanghai |
H. sekingeriana Heude, 1882 | 6 | 3.5–33/4 | 3.5 | Anhui |
H. sinensis Heude, 1882 | 4 | 5–6 | 3.5 | Yangtze River Valley |
H. spelaea Heude, 1882 | 6 | 4–4.5 | 3 | Jiangsu |
H. zikaveiensis Heude, 1882 | 4 | 2 | 1 | Shanghai |
H. crystallodes Gredler, 1885 | 5-5.5 | 5 | 2 | Hunan |
Scatter plot of canonical variate 1 against canonical variate 2 (yielded by canonical variate analysis), showing morphological relationship among Sinoxychilus melanoleucus gen. nov. and sp. nov. (red dots), Zonites scrobiculatus scrobiculatus Gredler, 1885 and Zonites scrobiculatus hupeina Gredler, 1887 (light blue dots), Indian Ariophanta spp. (
With respect to the genitalia, Sinoxychilus melanoleucus is similar to the Japanese Urazirochlamys doenitzii (Reinhardt, 1877) (Helicarionidae sensu
With the exception of two genera distributed in the southwestern part of the Arabian Peninsula, oxychilid snails are only known from the Western Palearctic (
Maximum likelihood tree based on ITS2 gene (-ln likelihood = −1746.99). Ingroups: Euconulus Reinhardt, 1883 (Euconulidae), Vitrea Fitzinger, 1833 (Pristilomatidae), Oxychilus Fitzinger, 1833 (Oxychilidae), and Sinoxychilus gen. nov. (Oxychilidae). This ML tree shares the same topology with the Bayesian Inference tree. Numbers on branches indicate maximum likelihood and Bayesian posterior probabilities.
We sincerely thank Dr Barna Páll-Gergely for helpful comments and providing his manuscript in press for reference. Our thanks go to Dr Eike Neubert and Dr Ivailo Dedov for helpful comments on this manuscript. We thank Hongwen Ma for fieldwork. We are indebted to the Biodiversity Heritage Library (http://www.biodiversitylibrary.org) for the access to rare literature.
This study was supported by the National Natural Science Foundation of China (NSFC 31872196).