taxonID	type	description	language	source
001A90252239BE62FC115EB74A934A72.taxon	type_taxon	TYPE SPECIES. — Paludina quadrata Benson, 1842, by original designation.	en	Hsu, Chia-Hsin, Osipova, Diana, Lin, Chien-Hsiang (2025): Fossil freshwater mollusks from the Early Pleistocene (Calabrian) of northern Taiwan. Geodiversitas 47 (20): 721-737, DOI: 10.5252/geodiversitas2025v47a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a20.pdf
001A90252239BE6FFC795F50484449C0.taxon	description	(Figs 4, 5)	en	Hsu, Chia-Hsin, Osipova, Diana, Lin, Chien-Hsiang (2025): Fossil freshwater mollusks from the Early Pleistocene (Calabrian) of northern Taiwan. Geodiversitas 47 (20): 721-737, DOI: 10.5252/geodiversitas2025v47a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a20.pdf
001A90252239BE6FFC795F50484449C0.taxon	materials_examined	MATERIAL EXAMINED. — Taiwan • 37 specimens; Shuiniukeng (= Water Buffalo Valley), New Taipei City; Tananwan Formation; Early Pleistocene, Calabrian; ASIZF 0100893 - ASIZF 0100912, ASIZF 0100923 - ASIZF 0100939.	en	Hsu, Chia-Hsin, Osipova, Diana, Lin, Chien-Hsiang (2025): Fossil freshwater mollusks from the Early Pleistocene (Calabrian) of northern Taiwan. Geodiversitas 47 (20): 721-737, DOI: 10.5252/geodiversitas2025v47a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a20.pdf
001A90252239BE6FFC795F50484449C0.taxon	description	DESCRIPTION Shell turbiniform, elongate subconical, appears thin, but not fragile. Medium to large in size, with HSh and WSh of adult shell ranging from 25 - 40 mm and 15 - 25 mm, respectively. HBW of adult shell about 70 % of HSh. HA longer than WA. Shell solid, whorls profile rounded with distinct periphery, sutures impressed but shallow on early whorls, and deep suture of the body whorl. Surface shiny with weak growth lines, with 1 - 3 loose spiral keels (better visible on the last whorl), not evident in some specimens. Spire rather short, rounded, consists of 4 - 5 whorls that enlarged slowly; ratio of 1: 1.5 to body whorl. Aperture subovate, broad, and prosocline, well angled posteriorly. Umbilicus small and narrow. Subadult shells (Fig. 4 M) with pronounced 2 - 3 spiral keels that become less prominent with age. Juvenile shell (Fig. 5 B-E) conical, turbiniform, early protoconch of 3 whorls with evident 2 - 3 ridges.	en	Hsu, Chia-Hsin, Osipova, Diana, Lin, Chien-Hsiang (2025): Fossil freshwater mollusks from the Early Pleistocene (Calabrian) of northern Taiwan. Geodiversitas 47 (20): 721-737, DOI: 10.5252/geodiversitas2025v47a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a20.pdf
001A90252239BE6FFC795F50484449C0.taxon	discussion	REMARKS Viviparid snails exhibit modest sexual dimorphism within species, due to their ovoviviparous reproductive strategy (Minton & Wang 2011). Additionally, shell shape variation, partly influenced by environmental factors, sometimes leads to slight morphological differences between closely related species (Chiu et al. 2002). For instance, Sinotaia quadrata histrica (Gould, 1859) inhabiting lagoonal environments develops thicker, more elongated shells with narrower apertures comparing to those found outside the lagoon (Kagawa et al. 2019). A similar case involves the often co-occurring invasive Cipangopaludina chinensis (Gray, 1833) and C. japonica (Martens, 1861) in the United States, which are morphologically indistinguishable, likely due to their shared habitats (Van Bocxlaer & Strong 2016). These phenotypic variations make species identification in viviparids challenging if relying solely on shell morphology. Moreover, the taxonomic uncertainty surrounding viviparid species has persisted since the 19 th century and remains unresolved (Van Bocxlaer & Strong 2019; Ye 2020; Stelbrink et al. 2020). In this study, the juvenile specimens played a crucial role in identifying S. quadrata. Juvenile shells from the Tananwan Formation closely resemble the outline and microsculpture of extant juvenile shells of S. quadrata (Fig. S 1 A, B). Compared to C. chinensis juveniles (Fig. S 1 C), the Tananwan juveniles have a less angular outline and the widest point positioned closer to the anterior. They also differ from C. japonica juveniles (Fig. S 1 D) in having a larger spire whorl angle, resulting in a distinct outline. While typical adult shells of these species differ significantly from our specimens (Fig. S 1 E-H), the Tananwan specimens share similarity with some of the morphotypes of those species (Fig. S 1 I-L), though the Tananwan adults are smaller than C. chinensis and C. japonica. Thus, based on both juvenile and adult shell morphology, our specimens are most likely belong to S. quadrata. This species has a wide distribution in East Asia, with records from China (Yen 1943), Korea (Lee 2009), and Japan (Hirano et al. 2015; Saito & Kagawa 2020). In Taiwan, this species was first reported as Viviparus angularis (Müller, 1774), followed by more recent studies (Pace 1973; Chiu et al. 2002). Chen (2011) summarized at least 12 varieties of shell morphotypes of S. quadrata across Taiwan. In addition, the subspecies S. quadrata heudei (Dautzenberg & Fischer 1905) is distinguished by its smaller shell with three well-defined spiral keels (Chen 2011). However, this subspecies has been recognized as synonym of the S. quadrata (Qian et al. 2014; Ye 2020). Fossil occurrences of S. quadrata are known from Pleistocene deposits in Asia (Taiwan Malacofauna Database 2013; Ye et al. 2020). Yen (1943) referred to this species as Viviparus quadratus Benson, 1843 from the Para-loess Formation (possibly Late Pleistocene) in the Yangtze Valley. This species has also been identified in the Upper Pleistocene deposits in Maping (Liuchow), Kwangsi, and Maoshan, Chuyung, Kiangsu (Yen 1943), as well as from Toning and Hainan (Odhner 1930). Yen (1943) synonymized † Bithinia viviparoides Hsu, 1936 from the Siashu Formation (Late Pleistocene), Nanking, China (Hsu 1936), with S. quadrata. Additionally, Viviparus quadratus limnophilus Mabille, 1886, which Yen (1943) synonymized with Vivipara dispiralis Heude 1890, was recorded from the post-Pleistocene period in Kweilin, Kwangsi (Hsu 1935).	en	Hsu, Chia-Hsin, Osipova, Diana, Lin, Chien-Hsiang (2025): Fossil freshwater mollusks from the Early Pleistocene (Calabrian) of northern Taiwan. Geodiversitas 47 (20): 721-737, DOI: 10.5252/geodiversitas2025v47a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a20.pdf
001A90252234BE6FFED35D944A3D4881.taxon	type_taxon	TYPE SPECIES. — Melanoides fasciolata Olivier, 1804, by monotypy.	en	Hsu, Chia-Hsin, Osipova, Diana, Lin, Chien-Hsiang (2025): Fossil freshwater mollusks from the Early Pleistocene (Calabrian) of northern Taiwan. Geodiversitas 47 (20): 721-737, DOI: 10.5252/geodiversitas2025v47a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a20.pdf
001A90252234BE6EFC115F764B554886.taxon	description	(Fig. 6 A-G)	en	Hsu, Chia-Hsin, Osipova, Diana, Lin, Chien-Hsiang (2025): Fossil freshwater mollusks from the Early Pleistocene (Calabrian) of northern Taiwan. Geodiversitas 47 (20): 721-737, DOI: 10.5252/geodiversitas2025v47a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a20.pdf
001A90252234BE6EFC115F764B554886.taxon	materials_examined	MATERIAL EXAMINED. — Taiwan • 8 specimens; Shuiniukeng (= Water Buffalo Valley), New Taipei City; Tananwan Formation; Early Pleistocene, Calabrian; ASIZF 0100913 - ASIZF 0100919, ASIZF 0100940.	en	Hsu, Chia-Hsin, Osipova, Diana, Lin, Chien-Hsiang (2025): Fossil freshwater mollusks from the Early Pleistocene (Calabrian) of northern Taiwan. Geodiversitas 47 (20): 721-737, DOI: 10.5252/geodiversitas2025v47a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a20.pdf
001A90252234BE6EFC115F764B554886.taxon	description	DESCRIPTION Shell turriculate, thick, elongated, with HSh being greater than twice of WSh. HBW and HSp of adult shell about 60 % and 40 % of HSh respectively. HA longer than WA. Surface smooth on last two whorls, but adapical whorls covered with widely spaced, prosocline collabral undulations. Spiral threads on abapical part of the base. Spire tall, comprising 2 / 3 of the shell. Suture shallow, but impressed in adapical whorls, last two whorls with slight shoulder at shallow suture. Whorls 7 - 8 in number (early whorls missing), increasing in diameter slowly, profile flattened. Aperture ovate, but not well preserved in all specimens.	en	Hsu, Chia-Hsin, Osipova, Diana, Lin, Chien-Hsiang (2025): Fossil freshwater mollusks from the Early Pleistocene (Calabrian) of northern Taiwan. Geodiversitas 47 (20): 721-737, DOI: 10.5252/geodiversitas2025v47a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a20.pdf
001A90252234BE6EFC115F764B554886.taxon	discussion	REMARKS Thiaridae species exhibit considerable polymorphism in shell ornamentation, which allows them to adapt to diverse environments across their range. In some lineages, predominantly parthenogenetic reproduction results in minimal intrapopulation variability in key morphological traits, allowing for regional morphological comparisons and identification (Samadi et al. 2000). The studied specimens closely resemble extant Melanoides tuberculata (Müller, 1774) populations in Taiwan (Chiu 2006; Chen 2011). These shells are characterized by the general shell outline and the presence of wavy longitudinal ribs on each whorl, which become less distinct towards the body whorl. They also differ from other Taiwanese thiarids. Specifically, Stenomelania costellaris (Lea & Lea, 1851) has more distinct sutures and smaller shells; S. plicaria (Born, 1778) exhibits smoother and higher shells; S. torulosa (Bruguière, 1789) displays thick longitudinal ribs with spiral grooves. However, due to the strong morphological variations within Thiaridae species, fragmentation of the specimens, and the lack of criteria for observing adult shell characteristics, we identified the specimens as Melanoides aff. tuberculata. Melanoides tuberculata has been reported from various localities across East Asia. In Taiwan, it was first described M. formosensis as a new species alongside M. tuberculata, while it has been suggested that M. formosensis may be a morphotype or a subspecies of M. tuberculata (Pace 1973). Chen (2011) documented possible shell morphological variations throughout Taiwan, demonstrating that such variability can be observed even among individuals from the same locality. Fossil occurrences of M. tuberculata from Neogene and Quaternary deposits are rare in Asia. Nomura (1935) reported this species from the Pleistocene Toukoshan Formation (referred to as Byoritu Beds in his report) in Houlong Township, Miaoli County (= Wangwa, Shinchiku-shu), northern Taiwan. Although the figure in the original publication is difficult to interpret, the accompanying description serves as evidence of its occurrence in Taiwan. Furthermore, Nomura (1935) also indicated its presence in the Miocene-Pliocene deposits of Java. Additionally, M. tuberculata has been reported from the Neogene of Nepal (Gurung et al. 1997).	en	Hsu, Chia-Hsin, Osipova, Diana, Lin, Chien-Hsiang (2025): Fossil freshwater mollusks from the Early Pleistocene (Calabrian) of northern Taiwan. Geodiversitas 47 (20): 721-737, DOI: 10.5252/geodiversitas2025v47a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a20.pdf
001A90252235BE6EFC7859764A934C8D.taxon	type_taxon	TYPE SPECIES. — Planorbis albus Müller, 1774, by subsequent designation.	en	Hsu, Chia-Hsin, Osipova, Diana, Lin, Chien-Hsiang (2025): Fossil freshwater mollusks from the Early Pleistocene (Calabrian) of northern Taiwan. Geodiversitas 47 (20): 721-737, DOI: 10.5252/geodiversitas2025v47a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a20.pdf
