From the Early Oligocene of the Nanning Basin (Guangxi, SE China)

Home , Ampullarioidea, Architaenioglossa, Margarya, Tulotoma, Viviparidae, Viviparus

N. Jb. Geol. Paläont. Abh. 267/1, 75–87 Article Published online December 2012

Giant Viviparidae (Gastropoda: Architaenioglossa) from the Early Oligocene of the Nanning Basin (Guangxi, SE China)

Tian Ying, Franz T. Fürsich and Simon Schneider With 5 figures and 2 tables

Ying, T., Fürsich, F.T. & Schneider, S. (2013): Giant Viviparidae (Gastropoda: Architaenioglossa) from the Early Oligocene of the Nanning Basin (Guangxi, SE China). – N. Jb. Geol. Paläont., 267: 75-87; Stuttgart.

Abstract: The rich freshwater mollusc fauna from the Lower Oligocene Gongkang Formation (Yongning Group) of the Nanning Basin (Guangxi Province, SE China) has yielded shells of two species of giant viviparid gastropods, which are described as Margarya nanningensis n. sp. and Macromargarya aliena n. gen. n. sp. The genus Margarya Nevill, 1877 has so far been thought to be endemic to the Pleistocene to Recent freshwater lakes of Yunnan Province (SW China), and is first described from the Oligocene of Guangxi herein. With a maximum height of more than 100 mm, Macromargarya aliena is among the largest freshwater gastropods reported to date. Moreover, M. aliena displays a strange ontogeny. An early, very low-trochospiral growth stage is followed by a rapid shift of the coiling axis and whorl proportions, leading to regular viviparid morphology in adulthood.

Key words: Taxonomy, Margarya, freshwater, East Asia, body size.

Introduction With a few exceptions, the Viviparidae are char- acterised by medium high-spired shells with moder- Large freshwater gastropods of the family Viviparidae ately to strongly inflated whorls that are often more are today distributed on all continents except South or less circular in cross-section and separated by deep America (where they are recorded as fossils; Wenz sutures. The large, thin, horny operculum lacks cal- 1938-1944) and Antarctica. They usually occur in careous carbonate and is usually not preserved in fos- lakes, ponds, and lentic rivers of temperate to tropical silized specimens. In most species, the shells are thin, regions (Strong et al. 2008). Currently, approximately often stabilized by spiral ribs or bands, and relatively 150 species in 30 genera are recognised in the Vivip- large, ranging between 25 and 70 mm in height. aridae (Strong et al. 2008), several of which have been Based on their near-global distribution and abun- assigned to the three subfamilies Viviparinae, Lio- dance, the Viviparidae are thought to have evolved placinae, and Bellamyinae (Bouchet & Rocroi 2005). before the break-up of the Pangaea supercontinent, For more than half of the genera, however, the exact and thus at least during the Jurassic (Wenz 1938-1944; systematic position and phylogenetic relationships are Hamilton-Bruce et al. 2002; Strong et al. 2008). The unknown. highest diversity of extant Viviparidae is found in East

Fig. 1. A. Major tectonic units of China. Guangxi is demarcated by a thick black line. CCO = Central China Orogen; CT = Cathaysian Terrane; EG = Er-Guna Orogen; LT = Laoyeling Terrane; QAB = Qaidam Block; QIB = Qiangtang Block; QLB = Qilian Block; QTB = Quinhai Tibet Block; SGB = Songpan-Garze Belt; TID = Tianshan-Inner Mongolia-Daxinganling Orogen. B. Schematic geological map of Guangxi, showing the position of the Nanning Basin.

and Southeast Asia, comprising several widespread rope, however, provides several examples of Pliocene as well as endemic genera and species (Strong et al. endemic lake radiations in this group, leading to an 2008). The rich fossil record of Viviparidae in Eu- extraordinary high diversity of viviparids. In Lake Da- Giant Viviparidae (Gastropoda: Architaenioglossa) from the Early Oligocene 77

cia (Romania, Bulgaria; Lubenescu & Zazuleac 1985) comprising predominantly Proterozoic to Palaeogene and Lake Slavonia (Croatia, Bosnia, Serbia; e.g., Neu- sediments, while the south-eastern part of the prov- mayr 1869; Neumayr & Paul 1875), viviparids were ince is situated on the Cathaysian Terrane, which is represented by 50 and 35 species, respectively (see mainly composed of crystalline rocks (Fig. 1A, B). Harzhauser & Mandic 2008 for an overview). Nanning, which is the capital of the Guangxi Zhuang Literature on fossil Cenozoic freshwater gastro- Autonomous Region, is situated in the Nanning Basin pods from continental East Asia is scarce (see Yen in the southern part of this province, approximately 1943b; Suzuki 1949; and Neubauer et al. 2012 for an 150 km to the northeast of the border to Vietnam (Fig. overview). Fossil Viviparidae have, however, been 1B). The Nanning Basin is a late Mesozoic to early described from several regions, and seem to have Cenozoic pull-apart basin that is filled with an almost been widespread in East Asia since the Palaeogene. 700 m thick succession of Cenozoic sediments (Deng Eocene and Miocene viviparids from Thailand have & Wu 1992). Sedimentation started in the Palaeocene, been used in stable isotope studies (Udomkan et al. and the basin infill is dominated by deep to shallow 2003; Ratanasthien et al. 2008) and several Mi- lacustrine facies (Deng & Wu 1992). During the Late ocene mollusc assemblages dominated by viviparids Eocene and Early Oligocene, the sediments of the were reported from northern Thailand (Oyama 1978; Yongning Group were deposited. Based on mammal Songtham et al. 2005; Ugai et al. 2006). Viviparidae faunas (Chow 1958; Tang & Chow 1964), the group from the Upper Eocene–Lower Oligocene deposits of has been subdivided into the Upper Eocene Nadu For- northern Vietnam (Na Duong Basin, Lang Son Prov- mation and the Lower Oligocene Gongkang Forma- ince) were illustrated by Khuc (1991) and Böhme et al. tion, which has yielded the molluscs described below. (2011). Additionally, Oligocene to Pleistocene mollusc Later on, the discovery of several Anthracotheriidae assemblages that yielded viviparid gastropods have confirmed the Early Oligocene age of the Gongkang been described from Myanmar (Annandale 1919) and Formation (Zhao 1983, 1993). China (e.g., Mansuy 1918; Odhner 1930; Hsü 1935; Odhner (1930) and Hsü (1935) erroneously dated Yen 1935). Scattered additional records are listed in the sediments of the Gongkang Formation as Pliocene. detailed compilations of fossil freshwater molluscs of They regarded the rich mollusc assemblage as closely China (Yen 1943b) and East Asia (Suzuki 1949). related to the superficially similar fauna of the former The freshwater gastropod fauna of the Nanning Levantine Stage of Slavonia (Croatia, Bosnia, Serbia; Basin in Guangxi Province exhibits certain similari- see Harzhauser & Mandic 2008 for discussion of the ties to contemporaneous faunas at the family and ge- viviparid fauna of Lake Slavonia), and thus determined nus level, but differs from them by a remarkably high a Pliocene age. Today, the Nanning Basin is drained by diversity and extraordinary preservation. More than the Yong River, and is thus part of the southern catch- eighty years ago, Odhner (1930) was the first schol- ment area of the Pearl River. ar who described freshwater molluscs from the Oli- The gastropod fauna that yielded the specimens de- gocene deposits of Nanning. Based on shells collected scribed herein was discovered in a construction trench by W.J. Ding, Odhner (1930) detailed 20 species of near the city of Santang, which is located ca 2 km to freshwater molluscs, of which he regarded 18 species the northeast of Nanning (Fig. 2A; N 22°52.47’, E as new to science. His material yielded fragments of a 108°24.72’). The pit exposed a somewhat more than 6 single large viviparid species, which he described as m thick succession of the Gongkang Formation which Tulotoma gigas Odhner, 1930. A few years later, three consisted of well-bedded mud- and siltstones of differ- additional gastropod species, including the small vivi- ent colours (Fig. 2B). The gastropods are derived from parid Viviparus wongi Yen, 1936, were described by different levels in the section (Fig. 2B), and the two Yen (1936). Since then, the mollusc fauna of the Nan- species detailed herein do not co-occur in the same ning Basin fell into oblivion. horizons.

Geological overview Material and methods Tectonically, Guangxi Province is part of the South The large gastropods described herein where surface- China Block, which is subdivided into two large subu- collected from the outcrop at Santang by the first au- nits (Fig. 1A). The major part of Guangxi, including thor. Despite their impressive size, both species occur the area of Nanning, belongs to the Yangtze Terrane in high abundance, but are often fragmented due to 78 T. Ying et al.

Fig. 2. A. Schematic map of the Nanning area, showing the position of the outcrop at Santang (N 22°52.47’, E 108°24.72’). B. Schematic section of the succession at Santang. Sample levels are indicated by gastropod symbols. C. Photograph of the Santang section. D. Close-up of a claystone horizon with numerous specimens of Macromargarya. E. Weathered claystone block with Macromargarya.

compaction of the sediments and weathering at the Repository: The specimens are stored in the collections surface (Fig. 2D, E). Thus, only a minor portion of the of the Dalian Shell Museum (DLSM) at Dalian, Liaon- specimens could be collected with more or less entire ing Province, China. Extant specimens that are figured for comparison are stored in the collections of the Malaco- shells. The shells were carefully brushed cleaned with logical Department of the Natural History Museum Vienna water. Several specimens were cut along the length (NHMW). axis to investigate the internal structures of the shell. Measurements were taken with an electronic calliper (accuracy = 0.1 mm). Giant Viviparidae (Gastropoda: Architaenioglossa) from the Early Oligocene 79

Systematic palaeontology Hershler et al. 1990) (e.g., Viviparus zelebori Neumayr, 1869). In a series of studies, based on fossil gastropod faunas The systematic arrangement of the Gastropoda has from Southeast Asia and on the evolution of shell sculpture been adopted from Bouchet & Rocroi (2005) and Shu in the Viviparidae, Annandale (1919, 1924) rejected these et al. (2010). misinterpretations and classified the evolutionary lineage of Margarya as distinct from that of the fossil viviparids from Europe. Obviously, his results were disregarded by Odhner Class Gastropoda Cuvier, 1795 (1930), as well as many later scholars. Subclass Orthogastropoda Ponder & Lindberg, 1995 Superorder Caenogastropoda Cox, 1960 Order Architaenioglossa Haller, 1890 Margarya nanningensis n. sp. Superfamily Ampullarioidea J. E. Gray, 1824 Fig. 3A, D-J Family Viviparidae J. E. Gray, 1847 Genus Margarya Nevill, 1877 Material: Twenty well preserved shells. Holotype: Speci- men DLSM1052007 (Fig. 3A, D-G); Paratype 1: Specimen Type species: Margarya melanioides Nevill, 1877, by DLSM1008 (Fig. 3H-J). Paratype 2: Specimen DLSM1009 subsequent designation in Yen (1939, 1943a) and Tchang & (not figured). Tsi (1949). Derivatio nominis: Named after the city of Nanning, the Diagnosis: “Shell large, up to about 70 mm in width, thick capital of Guangxi Province, in the vicinity of which the and extremely stout; 6–7 shouldered whorls, a very clear fossils have been found. ramp-like area on the upper portion of each whorl, gener- ally with prominent keels, tubercles or spines; apex obtuse; Locus typicus: Construction trench near Santang, ca 2 km aperture ovate; umbilicus small or absent; operculum cor- to the northeast of Nanning (N 22° 52.47’, E 108° 24.72’). neous and ovate.” (adopted from Shu et al. 2010).

Remarks: The genus Margarya is based on the Recent spe- Table 1. Measurements of Margarya nanningensis n. sp. cies Margarya melanioides, which has been first described (in mm). H = total shell height; W = total shell width; AH by Nevill (1877). Eleven extant species of Margarya are = height of aperture; AW = width of aperture; BH = height considered as (potentially) valid (Shu et al. 2010). The ge- of body-whorl, SH = height of second whorl. nus is endemic to Yunnan Province in southwestern China and all species are confined to a single or a few small to Collection H W AH AW BH SH medium-sized lakes (e.g., Lake Dianchi, Lake Yilonghu, number Lake Erhai; Shu et al. 2010). Due to commercial fishing, DLSM 1052001 79.60 53.57 37.52 36.32 62.82 24.91 pollution, and habitat loss, all species are currently in se- vere decline or already extinct (Shu et al. 2010). In addition DLSM 1052002 77.14 48.74 36.26 36.82 56.97 23.19 to the modern species, Li (1987) erected two fossil species DLSM 1052003 69.53 47.89 32.53 28.76 51.42 19.22 of Margarya, M. spinicostata and M. angulata, from the DLSM 1052004 77.96 48.16 34.76 30.82 55.72 21.44 Pleistocene Sheshan Formation in Yunnan. The similarity of the new species described below to DLSM 1052005 69.99 47.70 33.99 30.88 54.83 22.16 the type species of Margarya, M. melanioides is striking DLSM 1052006 68.13 45.47 32.51 30.01 51.58 17.44 (Fig. 3F, G). Although numerous cases of astonishingly de- DLSM 1052007 68.04 53.99 35.17 35.23 54.13 19.20 tailed convergence are known from freshwater gastropods, including viviparids (e.g., Annandale 1919, 1924), a close DLSM 1052008 73.46 50.27 32.15 29.13 53.68 21.24 relationship of the fossil and Recent species seems likely DLSM 1052009 80.76 53.62 35.04 30.29 58.18 23.17 in this case. Up to the Miocene, both the Yunnan lakes and Nanning Basin presumably belonged to the expansive Pal- DLSM 1052010 74.02 54.09 41.20 38.47 62.29 21.34 aeo-Red River catchment area (Clift et al. 2008; Hoang et DLSM 1052011 73.91 51.01 28.95 30.06 51.75 24.82 al. 2009; Schneider et al., in press), and migration along the DLSM 1052012 67.78 49.07 33.18 28.45 54.10 20.45 respective fluvial connections may have promoted the fossil and Recent distribution of Margarya. DLSM 1052013 74.67 58.00 34.47 31.05 58.11 19.99 The strongly distorted shells from the Middle Mi- DLSM 1052014 72.05 48.11 30.87 29.03 50.80 20.26 ocene of Thailand that were described as Margarya sp. by DLSM 1052015 64.29 52.05 33.04 29.80 53.71 19.19 Songtham et al. (2005) also share the diagnostic features of the genus, and potentially represent a southern offshoot of DLSM 1052016 69.42 48.23 34.23 25.84 54.39 19.90 Margarya, which used the Palaeo-Mekong as a vector. DLSM 1052017 69.09 48.12 33.66 30.30 55.23 20.62 Neumayr (1883) and Odhner (1930) regarded the genus DLSM 1052018 77.16 56.21 34.95 31.97 57.61 21.88 Margarya as being closely related to several fossil Euro- pean viviparids, which Neumayr (1883) had assigned to the DLSM 1052019 69.81 50.79 34.70 34.83 56.43 19.58 extant, monospecific genusTulotoma from Alabama (USA; DLSM 1052020 64.79 45.22 33.56 27.49 51.33 17.95 80 T. Ying et al. Giant Viviparidae (Gastropoda: Architaenioglossa) from the Early Oligocene 81

Stratum typicum: Gongkang Formation, Yongning Group, a result, M. melanoides lacks the angular, step-shaped out- Lower Oligocene. line seen in M. nanningensis, and has a more oval, slightly tear-shaped aperture (Fig. 3B). Moreover, M. nanningensis Diagnosis: Exceptionally large (H > 80 mm), thick-shelled is distinctly larger than all other species of Margarya. Margarya with short, stout spire and broad, angular whorls. Whorls ornamented with two prominent spiral bands, the upper one situated at the shoulder, the lower one near the base of the whorl. In adulthood, both spiral bands orna- Genus Macromargarya n. gen. mented with short, relatively densely spaced, blunt spines, emerging from strongly folded prominent growth lines. Type species: Macromargarya aliena n. sp.

Description: Shell thick, of exceptionally large size for the Derivatio nominis: From the Greek word “macros”, mean- genus (maximum height: 80.7 mm, maximum width 56.2 ing “large” referring to the extraordinarily large size of the mm; Table 1), comprising five to six whorls, which gradual- type species, especially in comparison to Margarya. ly increase in size; spire short, relatively stout. Suture deep. From third whorl onwards, whorls slightly detached, result- Diagnosis: Shells extremely large for viviparids (H > 100 ing in a slightly higher spire and much deepened suture. mm), very thick and solid, consisting of two differently Shoulder marked, angular; shallow-inclined adapical ramp shaped parts. First 3 to 3.5 whorls very low-trochospiral meeting almost vertical outer whorl at an angle of ca 120°. (apical angle ca. 130°); apex distinct; umbilicus wide; shoul- Shoulder of first three whorls sculptured with a rounded ca- der ornamented with thick, well-rounded band of lobate rina, set off by shallow spiral grooves on both sides. Sec- spines, causing blossom-like shape in upside view. Transi- ond, slightly less conspicuous carina situated directly above tion to second growth stage smooth but rapid; curling axis suture, set off by a single shallow spiral groove from whorl abruptly shifting for ca. 10°. Second shell portion consisting flank; carina becoming equally prominent as on shoulder of 2.5 whorls; high-conical (apical angle ca. 45°); ornament- with gradual detachment of whorls. In some specimens, one ed with a single broad, blunt central carina, carrying low, or two additional, weak, subordinate carinae inserted be- densely spaced open spines; umbilicus closed. tween two major carinae. Carinae causing rounded-rectan- gular, step-shaped outline of spire whorls and body whorl. Remarks: In its mature growth stage, Macromargarya n. From third whorl onwards, both spiral bands ornamented gen. basically resembles several species of Margarya, in with rows of relatively densely spaced spines; 11 to 12 major particular M. spinicostata Li, 1987 from the Oligocene of spines on shoulder carina of body whorl; 15 to 16 promi- Yunnan, which is cone-shaped and ornamented with a sin- nent spines on basal carina of body whorl. Spines bluntly- gle central carina carrying relatively widely spaced, long, rounded, relatively short; emerging from shell surface in open spines. Another species of similar shape, which is also the form of strongly folded, detached major growth lines; ornamented with a central carina carrying open spines, is spines open at abapical side, lunate in cross-section. Ap- the extant Acanthotropis partelloi (Bartsch, 1910), which is erture large, nearly circular; columellar and basal margins endemic to Lake Lanao (Mindanao, Philippines). However, markedly bent outward, forming moderately developed lip. Macromargarya differs from any other viviparid gastropod Umbilicus closed. genus in its strange, unique ontogeny, passing from an early, low-trochospiral growth stage to a high-conical adult shell Remarks: Margarya nanningensis resembles the type spe- with a marked shift of the coiling axis. cies of the genus, M. melanioides Nevill, 1877 (Fig. 3B, C) both with regard to general shell shape and ornamentation, but is stouter and has a significantly shorter spire. M. s nanningensis is ornamented with two major spiral carinae Macromargarya aliena n. p. carrying spines, the most prominent one being the one on Figs 4A-H, 5A-E the shoulder. In contrast, M. melanioides has a single domi- nant carina, carrying a row of spines or nodes, at about mid Material: Six well preserved shells and four apical frag- height of the whorls; this major carina may be accompanied ments. Holotype: Specimen DLSM105223 (Fig. 4A-E). by two or more subordinate, smooth or nodose carinae. As Paratype 1: Specimen DLSM105221 (Fig. 4F-H). Paratype

Fig. 3. A, D-J. Margarya nanningensis n. sp. from the Lower Oligocene Gongkang Formation, Santang, Guangxi Province, SE China. A, D-G. Holotype DLSM 105208. A. Frontal view. D. Back view. E. Apical view. F. Umbilical view. G. Lateral view. H-J. Paratype DLSM105207. H. Lateral view. I. Frontal view. J. Back view. B, C. Margarya melanioides Nevill, 1877; extant; Yunnan Province (exact locality unknown). B. Large adult specimen. C. Subadult specimen. Scale bar = 10 mm. 82 T. Ying et al.

Fig. 4. Giant Viviparidae (Gastropoda: Architaenioglossa) from the Early Oligocene 83

2: Specimen DLSM105225 (not figured). Apex fragment: Table 2. Measurements of Macromargarya aliena n. gen. et Specimen DLSM105321. n. sp. (in mm). For abbreviations see Table 1. Collection Derivatio nominis: From the Latin word “alienus”, mean- SH SW AH AW BH SH ing “strange”, referring to the abrupt shift of the curling axis number and change of whorl geometry. DLSM 105221 97.64 56.51 47.13 36.81 46.51 23.91 DLSM 105122 94.45 62.95 43.10 40.41 43.64 25.06 Locus typicus: Construction trench near Santang, ca 2 km to the northeast of Nanning (N 22° 52.47’, E 108° 24.72’). DLSM 105223 94.70 56.55 41.75 36.51 41.42 26.40 DLSM 105224 109.61 62.44 42.42 37.68 43.29 30.84 Stratum typicum: Gongkang Formation, Yongning Group, DLSM 105225 100.91 52.38 47.91 35.26 48.4 22.82 Lower Oligocene. DLSM 105226 102.87 58.92 44.83 36.37 44.96 24.95 Diagnosis: As for the genus.

Description: Shells very large; adult specimens 94 to 109 carina ornamented with spines and a similarly shaped ap- mm in height (Table 2), usually comprising six whorls; shell erture, but lacks the peculiar, blossom-shaped first growth very thick and solid, consisting of two differently shaped stage and shift of coiling axis. Moreover, M. spinicostata is parts. First 3 to 3.5 whorls very low-trochospiral; apical distinctly smaller than Macromargarya aliena. angle ca. 130°; apex distinct but blunt; umbilicus wide, ac- All the special features seen in Macromargarya aliena – counting for ca. 15% of shell width. Adapical part of whorls the shifting coiling axis, the change in whorl geometry and slightly flattened; partly ornamented with minute spiral to ornamentation, and the infill of the early shell whorls – do tangential furrows. Shoulder ornamented with thick, well- not occur accidentally or are teratologies, but represent typi- rounded band of hollow, flattened, rounded-lobate spines cal characters of the species. This becomes obvious from (7-8 spines on last whorl of first ontogenetic stage), set off the numerous shells occurring in high densities in a single from adapical shell portion by a shallow but distinct furrow; horizon at Santang (Fig. 2D, E). The carbonate fill of the ornamentation resulting in a blossom-like shape in upside early whorls consist of thin, regular, aragonitic growth in- view (Fig. 5). Growth lines distinct but smooth. Suture dis- crements (Fig. 5D, E) and exhibits the typical microstruc- tinct. Aperture almost circular. Transition to second growth ture of the gastropod shell; it is thus clearly biogenic and not stage smooth and gradual, but relatively rapid, within ca 10 diagenetic in origin. mm of shell growth; shift of curling axis achieved by dis- proportionate insertion of new shell material, with a maximum at the outer side of whorl; curling axis shifting for ca. Discussion and conclusions 10°. Second shell portion consisting of 2.5 whorls; high- conical; apical angle ca. 45°. Adapical portion of whorls The mollusc shells from the Oligocene Gongkang steeply inclined, almost straight; whorl centre ornamented Formation in Nanning Basin are exceptionally well with a single broad, blunt carina; carina ornamented with preserved. Altogether, the assemblages are remark- low, densely spaced spines (> 25 spines on body whorl). ably diverse and more than 25 species of bivalves and Spines emerging from regions above and below carina; gastropods have been described by Odhner (1930) and widely open in growth direction, with an arcuate cross-section. Abapical whorl portion slightly rounded. Suture deep. Yen (1936). Despite these thorough studies, the two Minute umbilicus covered by inner lip. Aperture rounded to impressively large viviparid species described herein slightly tear-shaped. are new to science. Surely, these gastropods have not Whorls, in particular those of early growth stage, gradu- been overlooked by previous workers, but simply were ally becoming filled with thin layers of shell material; in not present in the outcrops exposed in the early 20th adult individuals, first 2.5 to 3 whorls completely filled. century, which may indicate a significant sampling Remarks: Due to its unique ontogeny, Macromargarya al- bias. Moreover, several strange taxa of unresolved iena cannot be confused with any other viviparid. Its second affinities, such as the unionids Tuberonaia tuberosa ontogenetic stage resembles Margarya spinicostata Li, 1987 (Odhner, 1930) and Rhombunio spinifer Odhner, from the Pleistocene of Yunnan, which also has a central 1930, the gastropod Sinomelania leei Yen, 1936, and

Fig. 4. Macromargarya aliena n. gen. et n. sp. from the Lower Oligocene Gongkang Formation, Santang, Guangxi Province, SE China. A-E. Holotype DLSM 105223. A. Back view. B. Apical view. C. Side view. D. Umbilical view. E. Frontal view. F-H. Paratype DLSM105221. F. Side view. G. Back view. H. Frontal view. Scale bar = 10 mm. 84 T. Ying et al.

Fig. 5. A-E. Macromargarya aliena n. gen. et n. sp. from the Lower Oligocene Gongkang Formation, Santang, Guangxi Province, SE China. A-C. Apical shell fragment, showing first growth stage and transitional part to second growth stage (DLSM10532) A. Apical view. B. Slightly oblique, frontal view. C. Downside view. D-E. Specimen DLSM105225. Scans of subcentral, longitudinal sections through shell. Fill of early whorls with biogenic carbonate is evident. Scale bar = 10 mm.

the newly described Macromargarya nanningensis, The gastropods described herein where sampled have been documented from the Nanning Basin, sug- from a 6 m-thick section, comprising less than 1% of gesting a high rate of endemism in the Palaeogene the sedimentary infill of the Nanning Basin (Deng & Nanning Lake. Wu 1992). Judging from the huge, largely undisturbed Giant Viviparidae (Gastropoda: Architaenioglossa) from the Early Oligocene 85 succession of more than 600 m of lake sediments, mous size of the fossil gastropods from Santang may which encompass a time span from the Palaeocene have several reasons. On one hand, the gastropods may to at least the mid Oligocene, and thus more than 25 simply have lived under optimal conditions, enabling Ma (Deng & Wu 1992), the Palaeogene Nanning Lake constant and rapid growth. On the other hand, preda- may be suspected to be an extremely long-lived lake. If tion may have promoted shell growth and strengthen- this is true, the high rate of endemism in the Nanning ing. Large teeth of malacophagous cyprinids occur Lake fauna and the discovery of further new mollusc in abundance in the sediment (personal observation species would be no surprise. T.Y.). However, predators surely have not induced the As outlined above, the presumed faunistic relation- prodigal production of carbonate in Macromargarya, ships of the Oligocene Nanning Lake of Guangxi and which resulted in the complete infilling of the early the Pleistocene to Holocene lakes in Yunnan may be shell whorls. The purpose of this behaviour, which explained by the evolutionary history of the drainage must have caused a massive weighting of the apical systems in southern China. Up to the Miocene, the shell portion, remains elusive. After almost 80 years Palaeo-Red River drained a major part of the region, of cessation, the description of the two giant viviparids including the present upper reaches of the Yangtze and from Santang provides a new glance at the fauna of Pearl River (Clift et al. 2008; Hoang et al. 2009; Sch- Nanning Lake – which is, however, only an initial, neider et al. in press), and its catchment area encom- small step towards our understanding of this unique passed the present-day Yunnan and Guangxi provinc- Oligocene biota. es. A record of Margarya from the Middle Miocene of northern Thailand remains dubious due to poor pres- Acknowledgements ervation (Songtham et al. 2005). If these shells truly belong to Margarya, they may have been dispersed We express our gratitude to Yin Jiarun (China University along the Palaeo-Mekong during the Miocene. of Geosciences, Beijing, China) for his instructive guidance With a height of ca 110 mm, Macromargarya aliena of this study. Wei Peng (Dalian) kindly furnished us with field information. We would also like to thank Zhang Xi- is among the largest freshwater gastropod reported so aoyu, curator at the Dalian Shell Museum (Dalian, China), far – and clearly the largest member of the Vivipari- for his keen interest, encouragement, and support. Helmut dae. Gastropods of similar size have been documented Sattmann and Eva-Maria Pribil-Hamberger (both Natu- from Permian freshwater deposits of Erdie (China) by ral History Museum Vienna, Austria) kindly enabled ac- Pan & Yu (1993). The respective species, Omphalone- cess to extant gastropod specimens under their care. The specimens were photographed by Marie-Luise Neufert ma grandiosum Pan, reaches 105 mm in height and (AG PaläoUmwelt, Friedrich-Alexander Universität Erlan- 103 mm in width. Moreover, several gastropod spe- gen-Nürnberg) and Alice Schuhmacher (Natural History cies in the Upper Miocene Lake Pannon of Eastern Museum Vienna, Austria). A constructive review by Dan- Europe, i.e. lymnaeids of the genus Valenciennius and iela Esu (Università La Sapienza di Roma, Italy) distinctly the thiarid Tinnyea escheri vasarhelyii (Hantken) improved the manuscript. The research stay of Y.T. at the GeoZentrum Nordbayern, Friedrich-Alexander Universität arzhauser attained more than 100 mm in size (H & Erlangen-Nürnberg, was granted by the China Scholarship andic M 2008). Council (CSC), which is gratefully acknowledged. In an attempt to interpret the restricted occurrence of the large Permian Omphalonema grandiosum, Pan & Yu (1993) suggested that gigantism in freshwater References gastropod may herald the extinction of the respective Annandale, N. (1919): The gastropod fauna of Old Lake clade. Macromargarya aliena has been recorded from Beds in Upper Burma. – Records of the Geological Sur- a single level of the short section at Santang. Wheth- vey of India, 50: 209-240. er it occurs in additional horizons of the Gongkang Annandale, N. (1924): The evolution of the shell-sculpture Formation has to be checked. As a result, it remains in freshwater snails of the Family Viviparidae. – Pro- elusive whether M. aliena was a terminal member of ceedings of the Royal Society of London, Series B, Bio- logical sciences, 96: 60-76. an evolutionary lineage or rather a short-lived offshoot Bartsch, P. (1910): Notes on the Philippine pond snails of derived from a Margarya-like ancestor. The closely the genus Vivipara, with descriptions of new species. – related genus Margarya persists until today in the Proceedings of the United States National Museum, 37 lakes of Yunnan – although it may soon become ex- (1709): 365-367. tinct due to human impact. Böhme, M., Prieto, J., Schneider, S., Hung, N.V., Quang, D.D. & Tran, D.N. (2011): The Cenozoic on-shore ba- From a palaeoecological point of view, the enor- sins of Northern Vietnam: Biostratigraphy, vertebrate 86 T. Ying et al.

and invertebrate faunas. – Journal of Asian Earth Sci- logischen Reichsanstalt, 1869 (3): 355-382. ences, 40: 672-687. Neumayr, M. (1883): Über einige Süsswasserconchylien aus Bouchet, P. & Rocroi, J.-P. (2005): Classification and no- China. – Neues Jahrbuch für Mineralogie, Geologie und menclator of gastropod families. – Malacologia, 47: Paläontologie, 1883 (2): 21-26. 1-397. Neumayr, M. & Paul, C.M. (1875): Die Congerien- und Chow, M. (1958): Mammalian faunas and correlation of Paludinenschichten Slavoniens und deren Faunen. Ein Tertiary and Early Pleistocene of South China. – Journal Beitrag zur Descendenz-Theorie. – Abhandlungen der of the Palaeontological Society of India, Birbal Sahni kaiserlich-königlichen Geologischen Reichsanstalt, 7: Memorial, 3: 123-130. 1-111. Clift, P.D., Van Long, H., Hinton, R., Ellam, R.M., Han- Nevill, G. (1877): List of the Mollusca brought back by Dr. nigan, R., Tan, M.T., Blusztain, J. & Duc, N.A. (2008): Anderson from Yunan and Upper Burma, with descrip- Evolving east Asian river systems reconstructed by trace tions of new species. – Journal of the Asiatic Society of element and Pb and Nd isotope variations in modern and Bengal, 96: 14-41. ancient Red River-Song Hong sediments. – Geochemis- Odhner, N.H.J. (1930): Non-marine mollusca from Pliocene try, Geophysics, Geosystems, 9 (4): Q04039. deposits of Kwangxi, China. – Palaeontologia Sinica, Se- Deng, D. & Wu, Y. (1992): Features of the Palaeogene ries B, 6 (4): 7-29. sedimentary facies of the Nanning Basin, Guangxi. – Oyama, K. (1978): Late Caenozoic freshwater Mollusca Guangxi Geology, 65: 23-30. from Thailand. – Contributions to the Geology and Pal- Hamilton-Bruce, R.J., Smith, B.J. & Gowlett-Holmes, aeontology of Southeast Asia, 19: 161-165. K.L. (2002): Descriptions of a new genus and two new Pan, Y. & Yu, W. (1993): Permian Gastropoda of China. – species of viviparid snails (Mollusca: Gastropoda: Vivi- 68 pp.; Beijing (Ocean Press). paridae) from the Early Cretaceous (middle-late Albian) Ratanasthien, B., Takashima, I. & Matsubaya, O. (2008): Griman Creek Formation of Lightning Ridge, northern Paleaogeography and climatic change recorded on Vi- New South Wales. – Records of the South Australian viparidae carbon and oxygen isotope in Mae Moh Coal Museum, 35: 193-203. Mine, northern Thailand. – Bulletin of the Geological Harzhauser, M. & Mandic, O. (2008): Neogene lake sys- Survey of Japan, 59: 327-338. tems of Central and South-Eastern Europe: Faunal di- Schneider, S., Böhme, M. & Prieto, J. (in press): Unionidae versity, gradients and interrelations. – Palaeogeography, (Bivalvia: Palaeoheterodonta) from the Palaeogene of Palaeoclimatology, Palaeoecology, 260: 417-434. Northern Vietnam – exploring the origins of the modern Hershler, R., Pierson, J.M. & Krotzer, R.S. (1990): Redis- East Asian freshwater bivalve fauna. – Journal of Sys- covery of Tulotoma magnifica (Conrad) (Gastropoda: tematic Palaeontology (in press). Viviparidae). – Proceedings of the Biological Society of Shu, F., Köhler, F. & Wang, H. (2010): On the shell and rad- Washington, 103: 815-824. ular morphology of two endangered species of the genus Hoang, L.V., Wu, F.-Y., Clift, P.D., Wysocka, A. & Swierc- Margarya Nevill, 1877 (Gastropoda: Viviparidae) from zewska, A. (2009): Evaluating the evolution of the Red lakes of the Yunnan Plateau, Southwest China. – Mol- River system based on in situ U-Pb dating and Hf iso- luscan Research, 30: 17-24. tope analysis of zircons. – Geochemistry, Geophysics, Songtham, W., Ugai, H., Imsamut, S., Maranate, S., Tansa- Geosystems, 10 (11): doi:10.1029/2009GC002819. thien, W., Meesook, A. & Saengsrichan, W. (2005): Hsü, S.C. (1935). Fresh-water gastropods from Tertiary and Middle Miocene molluscan assemblages in Mae Moh Quaternary deposits of Kwangsi, S China. – Palaeonto- Basin, Lampang Province, northern Thailand. – Scien- logica Sinica, Series B, 6 (2): 1-41. ce Asia, 31: 183-191. Khuc, V. (Ed.) (1991): Paleontological atlas of Vietnam. Strong, E.E., Gargominy, O., Ponder, W.F. & Bouchet, Volume 3. Mollusca. – 207 pp.; Hanoi (Science and P. (2008): Global diversity of gastropods (Gastropoda; Technics Publishing House). Mollusca) in freshwater. – Hydrobiologia, 595: 149-166. Li, Y.T. (1987): Margarya and Paraprososthenia (Gastro- Suzuki, K. (1949): Development of the fossil non-marine poda) from the Sheshan Formation in Lijiang Basin, molluscan faunas in Eastern Asia. – Japanese Journal of West Yunnan. – Professional Papers of Stratigraphy and Geology and Geography, 21: 91-133. Palaeontology, 22: 313-321. Tang, X. & Chow, M. (1964): A review of vertebrate bearing Lubenescu, V. & Zazuleac, D. (1985): Les viviparidés du lower Tertiary of South China. – Vertebrata Palasiatica, Néogène Supérieur du Bassin Dacique. – Mémoires, 8: 119-133. Ministère de la Géologie, Institut de Géologie et de Tchang, X. & Tsi, Z.Y. (1949): A revision of the genus Mar- Géophysique, 32: 77-136. garya of the family Viviparidae. – Contributions from Mansuy, H. (1918): Paludinidae fossiles du bassin la- the Institute of Zoology, National Academy of Peiping, custre de Mong-Tseu Yunnan. – Bulletin du Service 5: 1-26. Géologique de l’Indochine, 5 (3): 1-7. Udomkan, B., Ratanasthien, B., Takayasu, K., Fyfe, W.S., Neubauer, T., Schneider, S., Böhme, M. & Prieto, J. (2012): Sato, S., Kandharosa, W., Wongpornchai, P. & Kusak- First records of freshwater rissooidean gastropods from abe, M. (2003): Fluctuation of depositional environment the Palaeogene of Southeast Asia. – Journal of Mollus- in the Bang Mark coal deposit, Krabi Mine, southern can Studies, 78: 119-127. Thailand: stable isotope implication. – Science Asia, 29: Neumayr, M. (1869): Beiträge zur Kenntniss fossiler Bin- 307-317. nenfaunen. – Jahrbuch der kaiserlich-königlichen Geo- Ugai, H., Ratanasthien, B. & Silaratana, T. (2006): Ceno- Giant Viviparidae (Gastropoda: Architaenioglossa) from the Early Oligocene 87

zoic freshwater molluscan fossils of Thailand. – Journal Manuscript received: December 8th, 2011. of the Geological Society of Thailand, 1: 67-82. Revised version accepted by the Tübingen editor: August Wenz, W. (1938–1944): Gastropoda. Allgemeiner Teil 8th, 2012. und Prosobranchia. – Handbuch der Paläozoologie, 6: 1-1639, Berlin (Borntraeger). Addresses of the authors Yen, T.C. (1935): On some Tertiary gastropods of Yunnan. – Bulletin of the Geological Society of China, 14: 315- Tian Ying, China University of Geosciences, 100083 339. Beijing, China and Dalian Shell Museum, 116023 Dalian, Yen, T.C. (1936): Notes on some Tertiary gastropods from China; Kwangsi. – Bulletin of the Geological Society of China, e-mail: [email protected]. Corresponding author. 4: 497-504. Franz T. Fürsich, GeoZentrum Nordbayern, Fachgruppe Yen, T.C. (1939): Die chinesischen Land- und Süsswasser- PaläoUmwelt, Friedrich-Alexander-Universität Erlangen- Gastropoden des Natur-Museums Senckenberg. – Ab- Nürnberg, Loewenichstr. 28, 91054 Erlangen, Germany; handlungen der Senckenbergischen naturforschenden e-mail: [email protected] Ges ellschaft, 444: 1-233. Simon Schneider, Natural History Museum Vienna, Yen, T.C. (1943a): A preliminary revision of the Recent spe- Geology & Palaeontology, Burgring 7, 1010 Wien, Austria; cies of Chinese Viviparidae. – Nautilus, 56: 124-130. e-mail: [email protected] Yen, T.C. (1943b): Review and summary of Tertiary and Quaternary non-marine molluscs of China. – Procee- dings of the Academy of Natural Sciences of Philadel- phia, 95: 267-309. Zhao, Z.R. (1983): A new species of anthracothere from Nanning Basin. – Vertebrata Palasiatica, 21: 266-272. Zhao, Z.R. (1993): New anthracothere materials from the Palaeogene of Guangxi. – Vertebrata Palasiatica, 31: 183-190.