A new Chinese species of Eostrobilops Pilsbry, 1927 with a checklist of Eostrobilops and Enteroplax Gude, 1897 species (Gastropoda, Pulmonata, Strobilopsidae).

Eostrobilopshumicolus Páll-Gergely & Hunyadi, sp. n. is described from Guangxi Province, China. It is characterized by the combination of a small shell (diameter: 2.3-2.4 mm), strongly ribbed dorsal surface, an infraparietal lamella not reaching the callus, and long basal folds. The new species is found approximately 500 and 800 km from the two nearest species Eostrobilopsinfrequens (northern Vietnam), and Eostrobilopsdiodontina (Hunan, China), respectively. A checklist of extant Eostrobilops Pilsbry, 1927 and Enteroplax Gude, 1899 species is provided. Enteroplaxyaeyamensis Habe & Chinen, 1974, Enteroplaxkanjiokuboi Minato & Tada, 1992 and Enteroplaxtaiwanica Minato & Tada, 1992 are moved to the genus Eostrobilops because of the lack of an elevated parietal callus and a peripheral thread. A map showing all Eostrobilops records is provided.

Introduction

The family is mainly defined on a conchological basis; the shell is trochiform, dome-shaped or discoidal, umbilicate and consists of 4.5–6 slowly increasing whorls. The aperture is oblique, peristome more or less thickened and expanded; the PageBreakends of the lips are connected by a parietal callus. The main characteristic feature of the family is the armature consisting of two or three parietal lamellae and several deeply-placed basal folds, all growing continuously from an early neanic state (Pilsbry 1927). Only four species belonging to two genera have been examined anatomically (Baker in Pilsbry 1935, 1948, Minato 1975, Matsumura and Minato 1998). None of these works revealed anatomical characters that would distinguish the from other orthurethran families, such as the and (Manganelli et al. 1989). Strobilopsid DNA sequences were published in two works, but neither of them focussed explicitly on the systematic position of the . In the phylogenetic tree of Tongkerd et al. (2004), which focussed on the family , (Say, 1817) nested within the valloniid clade. The closest taxon to is (Say, 1824) and two samples of (O. F. Müller, 1774) formed the sister clade of the - clade. The samples of () and () were more distantly related to than to the members of the . In the phylogenetic tree of Wade et al. (2006), which provided an overview of the phylogenetic relationships between most pulmonate groups, (Pilsbry, 1908) clustered with , and . In this analysis, was only included in the larger, orthurethran clade. These data show that is an orthurethran family, but its relationships with other families still require clarification.

Living occur in America, from northern Mexico to the northern part of South America, and East Asia, from North Korea and south-eastern Russia to southern Borneo (Pilsbry 1927, Kuroda and Miyanaga 1939, Solem 1968, Miller and Christensen 1980, Schileyko 1984, Vermeulen 1992a,b). Fossil strobilopsids have been reported from Europe, North and South America as well as China (as reviewed by: Wenz 1923, Pilsbry 1927–1935, Manganelli et al. 1989). The oldest fossils that have properly been assigned to the dated to the Middle Eocene of Europe. In the New World, fossils no older than from the Late Pliocene can be ascribed to the family. The assignment of Upper Cretaceous-Lower Tertiary Chinese and South American fossils to the is speculative only (Manganelli et al. 1989).

Pilsbry (1948) proposed that the family had radiated from Asia into Europe and the New World. By contrast, Ferreira and Dos Santos Coelho (1970) believed that South America has been the centre of origin of the family. Solem (1979, 1981) and Manganelli et al. (1989), however, stated that the radiation from a European centre was much easier to explain, especially if the Cretaceous fossils, which are not certainly strobilopsids, were ignored. Solem (1979, 1981) mentioned the as one of the most interesting cases of “moved” families, i.e. recent families that live far away from the main stock of their fossil records.

East Asia is inhabited by two recent strobilopsid genera: Gude, 1899 and Pilsbry, 1927, which differ from each other in the morphology of the parietal callus, the edge of the body whorl and the parietal lamellae. Herein, we describe a new species of from the Chinese province of Guangxi and provide a critically revised checklist of and species.

Material and methods

The nomenclature for the armature follows that of Pilsbry (1927). Scanning electron microscopy was undertaken on uncoated shells under a low vacuum SEM (Miniscope TM-1000, Hitachi High-Technologies, Tokyo). We counted shell whorls (to the nearest quarter of a whorl) following Kerney and Cameron (1979).

Comparative material. , Korea, Quelpart (= Cheju Island), det. Zilch (?), NHMUK 1909.2.20.112.114.; (labelled as ), Japan, Uzen, NHMUK 1912.6.28.19–20, NHMUK 1912.6.29.32–34; , 朝鮮京城府北渓山 (probably Cho-Sen Kei-Joh-Fu, Hoku-Kei-Zan), Sakurai collection, NSMT/2; , 中華民国 (台湾) 南投県信義郷東埔楽々温泉, Lo lo uen chuan, Tung-pu, Hsin-i shiang, Nan tou hsien, Taiwan, NSMT 69652/1 paratype; , China, Tchen-k’eou, leg. Farges, excoll Musée Heude, 03.01.1946, MCZ, 167133 (photos of a syntype were received from Jochen Gerber). We could not examine most types during our visit to the National Museum of Nature and Science, Tsukuba, Japan (11–13 March, 2015), because they were on loan. The comparisons of sp. n. with and were based on the original descriptions of these species.

Abbreviations

HA

Collection András Hunyadi, Budapest, Hungary

HNHM

Hungarian Natural History Museum, Budapest, Hungary

MCZ

Museum of Comparative Zoology, Massachusetts, USA

NHMUK

The Natural History Museum, London, United Kingdom

NSMT

National Museum of Nature and Science, Tsukuba, Japan

Results

Taxonomic description Family

Pilsbry, 1927

Pilsbry 1927 (as a section of

Type species.

Pilsbry, 1908, by original designation.

Páll-Gergely & Hunyadi sp. n.

http://zoobank.org/AE9A1A96-A8F8-4E94-B5E7-45A6452ADC20

Material.

China, Guangxi (广西), Hechi Shi (河池市), Tiane Xian (天峨県), Qimu Xiang (豈暮郷), road junction toward Lahaoyan (拉号岩), cliff overlooking a memorial, 600 m, 24°51.130'N, 107°11.670'E, leg. Hunyadi, 12.09.2013., HNHM 99419 (holotype, Figure 1A–C), HNHM 99420 (paratype, Figure 1D–E and 2), HA/5 paratypes.

Figure 1.

SEM images of sp. n. A–C holotype D–E paratype1 F paratype2.

Figure 2.

Drawing showing the lamellae and folds of sp. n. (paratype specimen, same as on Fig. 1D–E). Black lines: basal folds; grey lines: parietal and infraparietal lamellae. Dotted line indicates the supposed position of the parietal callus.

Diagnosis.

A small species with a strongly ribbed dorsal surface, an infraparietal lamella not reaching the callus, and long basal folds.

Description.

Shell small, light brown (only one shell in type material had original colour); trochiform, rather domed above, almost flat ventrally (umbilical side), periphery rounded, very slightly keeled, suture rather deep; 4.75 (n = 3) slowly expanding whorls, protoconch approximately 1.5 whorls; virtually smooth but with weak microscopic pits arranged in irregular radial lines; teleoconch irregularly ribbed; ribs strong dorsally, very weak ventrally (except for inside the umbilicus); spiral structure entirely lacking; umbilicus narrow; inner margin of the whorls exposed in umbilicus irregularly crenulated; aperture semilunar and oblique; peristome slightly thickened and slightly reflexed; parietal callus weak; parietal and infraparietal lamellae well-developed, although the infraparietal does not extend to the peristome; a low interparietal lamella deeply situated, not visible from aperture; three long basal folds and one short columellar lamella; basal folds visible in one specimen with a fresh, translucent shell only (Figs 1D–E, 2). However, this specimen was broken and the fold length can only be estimated (ca. a minimum of a quarter whorl).

Differential diagnosis.

Both and are much larger than the new species, they have a more rounded body whorl, wider umbilicus, and weaker dorsal sculpture. is larger and flatter than sp. n., has a weaker dorsal sculpture, both of its parietal lamellae extend to the peristome, and has a shorter basal folds. is similar to sp. n. by having a strongly ribbed dorsal surface and long basal folds, but differs in the larger size, wider umbilicus, and the serrated lamellae (not serrated in sp. n.); the infraparietal lamella extends to the callus (not in sp. n.), and has a long palatal fold, which is lacking in the new species. is slightly larger (D = 2.88, H = 1.75 mm), has more elevated parietal and infraparietal lamellae, and both lamellae attain the peristome. Moreover, has shorter basal folds. has a more elevated spire than sp. n., a stronger callus, a narrower umbilicus and shorter basal folds. The spire of is higher, it has more angulate periphery, thicker peristome and shorter basal folds.

Measurements

(in mm): D = 2.3–2.4, H = 1.45–1.5 (n = 2).

Etymology.

From Latin (‘humicolus’ = soil-dwelling), in reference to the fact that this species was found in soil samples.

Ecology.

No living specimens have been found. The empty shells were collected from a soil sample. sp. n. probably lives under stones and dead leaves on the soil.

Type locality.

China, Guangxi (广西), Hechi Shi (河池市), Tiane Xian (天峨県), Qimu Xiang (豈暮郷), road junction toward Lahaoyan (拉号岩), cliff overlooking a memorial, 600 m, 24°51.130'N, 107°11.670'E.

Distribution.

Known from the type locality only.

Remarks on species

Solem (1968) named three differences between the two genera: (1) has a raised parietal callus, lacking in , (2) has a “peripheral thread”, lacking in and (3) has superior serrated nodes on the parietal lamellae, missing in . The morphology of the callus and the periphery seem to separate the two genera well, because the raised callus is always associated with the peripheral thread and the weak callus is a characteristic feature of species which lack the peripheral thread. The serrated nodes on the lamellae, however, were not observed in at least three species (, sp. n. and ) which belong to based on the other two characters. Therefore, the serrated node is excluded from the diagnosis of . Future investigations may provide additional information on the utility of this character for the subdivision of .

, and have been described as species. However, they lack the thickened parietal callus, which is conspicuous in every species. Moreover, although they have a somewhat angular periphery, they lack a distinct “peripheral thread”, which is also characteristic for . Therefore, all these three species belong to the genus , as already proposed by Vermeulen (1992a) for .

No obvious teleoconch spiral lines are visible in the photo of the syntype of , as noted in the original description (Heude 1885, Pilsbry 1927).

The palatal fold, which is approximately a quarter whorl in length and runs just above the keel in the paratype of (see Material and methods) was not mentioned in the original description.

Vermeulen (1992a) compared with . He mentioned that “occasionally shows an interparietalis” and “may have an interparietalis”. This information is probably erroneous, because neither the original description (Habe and Chinen 1974), nor Minato (1982) mentioned an interparietalis lamella. Moreover, Vermeulen (1992a) mentioned that has two basal folds, whereas possesses three. However, the description and figure of Minato (1982) describes three basal folds, and interstitial basal plicae were mentioned in the original description of .

Checklist of and species, and their distributions (see also Fig. 3)

Distribution of species. 1, 2 (Pilsbry, 1927) 3 (Kuroda & Miyanaga, 1939) and (Kuroda & Miyanaga, 1939) 4, 5 (Pilsbry, 1927) 6 Matsumura & Minato, 1980 7 (Pilsbry, 1908) 8 (Heude, 1885) 9 sp. n. 10 (Minato & Tada, 1992) and (Minato & Tada, 1992) 11 (Habe & Chinen, 1974) 12 Maassen, 2006 13 Vermeulen, 1992.