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A New Species of the Genus Geoemyda (Chelonii: Geoemydidae) from the Upper Pleistocene of Tokunoshima Island, the Central Ryukyus, Japan

DOI:10.3105/1345-5834(2007)26[1:ANSOTG]2.0.CO;2
Authors:
Akio Takahashi at Okayama University of Science
Akio Takahashi
Takafumi Kato at Kurashiki University of Science and the Arts
Takafumi Kato
Hidetoshi Ota at University of Hyogo
Hidetoshi Ota
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Abstract

Turtle fossils discovered from the putative Upper Pleistocene fissure-filling deposit on Tokunoshima Island of the Amami Group is described as a new species, Geoemyda amamiensis (Chelonii: Geoemydidae). These fossils include a carapace exclusive of peripherals and a few other elements, fragments of a neural, a costal, eight peripherals, an anterior half of the plastron, two epiplastra, and an incomplete right humerus. Geoemyda amamiensis most resembles G. japonica, an extant species endemic to three islands of the Okinawa Group, but is distinguished from the latter by the presence in dorsal view of a short anterior projection in the entoplastron. These two species seem to have split from each other through vicariance within the central Ryukyus.
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Current Herpetology 26(2): 139, December 2007
2007 by The Herpetological Society of Japan
ERRATUM: “A New Species of the Genus Geoemyda
(Chelonii: Geoemydidae) from the Upper Pleistocene of
Tokunoshima Island, the Central Ryukyus, Japan”, by Akio
Takahashi, Takafumi Kato, and Hidetoshi Ota,
Current Herpetology 26(1): 1–11, 2007
A recent paper describing a new fossil
Geoemyda species, G. amamiensis, has errors
in the caption of Fig. 5. The authors would
like to correct these errors as below.
Original
FIG. 5. Plastra in dorsal views of Geoemyda
amamiensis and the two extant congeneric
species. A, G. amamiensis (RUMF-GF-5011,
holotype). B, G. japonica (KUZR R62453).
C, G. spengleri (KUZ R62351). Abbreviations
are: EPI, epiplastron; ENT, entoplastron;
HYO, hyoplastron. Scale bars equal 10 mm.
Corrected
FIG. 5. Plastra in dorsal views of Geoemyda
amamiensis and the two extant congeneric
species. A, G. amamiensis (RUMF-GF-5011,
holotype). B, G. spengleri (KUZ R62351). C,
G. japonica (KUZR R62453). Abbreviations
are: EPI, epiplastron; ENT, entoplastron;
HYO, hyoplastron. Scale bars equal 10 mm.
... By comparing fossils of different ages and from different localities, detailed paleobiogeographic patterns can be developed. Keeping this advantage in mind, we have been investigating taxonomic status and phylogenetic affinities of fossil terrestrial turtles discovered from the Upper Pleistocene in the Ryukyu Archipelago by making detailed comparisons on the basis of broad material (e.g., Takahashi et al. 2003Takahashi et al. , 2007. Here, we briefly review these turtles and discuss their paleobiogeographic implications. ...
... Nevertheless, detailed Late Pleistocene Turtles of Ryukyu . Takahashi et al. morphological investigations revealed distinct differentiation of this Tokunoshima endemic from that species (Takahashi et al. 2007). ...
... Discovery of G. amamiensis from Tokunoshima Island offers another case of substantial divergence in a single clade within the central Ryukyus (Takahashi et al. 2007). This is concordant with Ota's (1998) view that the primary vicariance within this region took place between this island and the Okinawa Group. ...
Systematic Review of Late Pleistocene Turtles (Reptilia: Chelonii) from the Ryukyu Archipelago, Japan, with Special Reference to Paleogeographical Implications
Article
Full-text available
  • Jun 2008
The Quaternary terrestrial turtle fauna of the Ryukyu Archipelago was reviewed on the basis of recently excavated fossils, as well as literature information. As a result, five extinct species (four geoemydids [Cuora sp., Geoemyda amamiensis, Mauremys sp., and another species with undetermined generic and specific status] and one testudinid [Manouria oyamai]) were recognized from Late Pleistocene cave and fissure deposits. Two of the three turtles currently occurring in this archipelago (C. flavomarginata and G. japonica) were also recognized from comparable deposits on islands, including those where they do not occur at present. These records indicate that the terrestrial turtles of the Ryukyus were much more diverse during the Late Pleistocene than at present, and that extinction has occurred during the last few tens of thousands of years not only for those five fossil species but also for some island populations of the extant species. Distributions of three of the extinct species (G. amamiensis, Cuora sp., and the geoemydid [genus and species undetermined]), confined to the central Ryukyus, are concordant with the currently prevailing hypothesis of Ryukyu paleogeography, which assumes a relatively long isolation of this region and much more recent insularization of the southern Ryukyus. In contrast, distributions of the remaining two extinct species (Man. oyamai and Mau. sp.) must be explained by some ad hoc scenario or, otherwise, drastic modification of the current hypothesis.
... In this paleozoogeographic inference, they made two a priori assumptions: (1) the emergence of the peninsula-like land bridge extending from the east Asian continent to the Central Ryukyus via Taiwan and the Southern Ryukyus in the middle Pleistocene, based on Kimura's (1996Kimura's ( , 2000 paleogeographic scenarios with slight modifications; and (2) the existence of an ancestral species for M. oyamai in the eastern margin of the east Asian continent in the late middle Pleistocene. However, Kimura's (1996Kimura's ( , 2000 paleogeographic hypotheses have hardly been supported by stratigraphic (Iryu et al., 2006;Osozawa et al., 2012), paleontological (Takahashi et al., 2007(Takahashi et al., , 2008Takahashi, 2015), or neontological (Hikida and Ota, 1997;Ota, 1998Ota, , 2000Motokawa, 2000;Matsui et al., 2005;Honda et al., 2014;Koizumi et al., 2014;Su et al., 2016;Yamaji et al., 2016) studies. Moreover, an extinct ancestral species for M. oyamai has hitherto not been discovered from the middle Pleistocene or from older deposits on the eastern margin of the Asian continent. ...
Systematic revision of Manouria oyamai (Testudines, Testudinidae), based on new material from the Upper Pleistocene of Okinawajima Island, the Ryukyu Archipelago, Japan, and its paleogeographic implications
Article
Full-text available
  • Apr 2018
Manouria oyamai, an extinct, endemic testudinid turtle known from the upper Pleistocene of the Ryukyu Archipelago, southwestern Japan, has been reviewed on the basis of new specimens. The new specimens consist of a skull, as well as the first records of the epiplastron and the pelvis, all of which were found in a late Pleistocene fissure-filling deposit on Okinawajima Island, the Central Ryukyus, Japan. The present material provided four new informative morphological characters for M. oyamai: the anterior epiplastral projection, the epiplastra lacking extensive overhanging lip, the wide and fan-shaped iliac blade, and the wide ischiadic plate. The results of morphological comparisons and phylogenetic analysis indicated that M. oyamai is sister to M. emys (occurring in Bangladesh, eastern India, Myanmar, Thailand, the Malay Peninsula, Sumatra, and Borneo), and that M. impressa (in southern China, Laos, Malaysia, Myanmar, Thailand, and Vietnam) is the basal-most taxon within Manouria. In addition, the extremely thin carapace observed in M. oyamai, which had been cited as one of three diagnostic characters of this species as well as a feature thought indicative of insular adaptation, is also present in M. impressa within this genus. The present observation therefore indicates that this character is not always attributable to insular adaptation. The results of this study along with the current paleogeographic hypothesis of the Ryukyu Archipelago suggest that M. oyamai had differentiated from an extinct ancestral species shared with M. emys on the eastern margin of Asian continent not later than the early Pleistocene. SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP Citation for this article: Takahashi, A., R. Hirayama, and H. Otsuka. 2018. Systematic revision of Manouria oyamai (Testudines, Testudinidae), based on new material from the Upper Pleistocene of Okinawajima Island, the Ryukyu Archipelago, Japan, and its paleogeographic implications. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2017.1427594.
... Recently Takahashi et al. (2007) described a Late Pleistocene fossil species, Geoemyda amamiensis, from Tokunoshima, an island ca. 120 km northeast of Okinawajima Island. ...
... Recently Takahashi et al. (2007) described a Late Pleistocene fossil species, Geoemyda amamiensis, from Tokunoshima, an island ca. 120 km northeast of Okinawajima Island. ...
... Faunistically, the Ryukyu Archipelago is classified into three regions: the Northern, Central, and Southern Ryukyus (Ota, 1998). Of these, the Central Ryukyus, consisting of the Amami and Okinawa Island Groups, are noted for the high abundance of relic species in the non-volant terrestrial fauna, supposedly reflecting its consistent isolation from adjacent land masses even during the periods when the remaining islands of the Ryukyus were connected to adjacent land masses (Ota, 1998(Ota, , 2000Takahashi et al., 2007). ...
... The archipelago is biogeographically classified into three regions: Northern, Central, and Southern Ryukyus (Ota, 1998). Of these, the Central Ryukyus region, consisting of the Okinawa and Amami Island Groups, and a few southern islets of the Tokara Island Group, is known to accommodate an especially high proportion of endemic taxa in non-volant terrestrial vertebrates that are in a more or less relict state (Matsui, 1994;Ota, 1998Ota, , 2000aTakahashi et al., 2007). ...
Phylogenetic Relationships, Genetic Divergence, Historical Biogeography and Conservation of an Endangered Gecko, Goniurosaurus kuroiwae (Squamata: Eublepharidae), from the Central Ryukyus, Japan
Article
The Kuroiwa's eyelid gecko Goniurosaurus kuroiwae is an endangered species in a state of relict endemism in the Central Ryukyus, Japan, and is divided into five subspecies. We analyzed variations in sequence data for approximately 1900 base positions of mitochondrial 12S and 16S rRNA, and cytochrome b genes from samples representing all recognized subspecies of G. kuroiwae together with those from congeneric species in order to test the relevant previous phylogenetic hypotheses and discuss biogeographical implications in the degree and pattern of genetic divergence within G. kuroiwae. Our results, while confirming a previous molecular phylogenetic hypothesis proposed on the basis of much smaller data set, negate the relationships hypothesized on morphological grounds by explicitly supporting: 1) the primary dichotomy, with substantial genetic divergence, between G. k. splendens from the Amami Island Group and the remaining subspecies all from the Okinawa Island Group; and 2) the presence of at least six independent lineages within the latter, indicating non-monophyly for two of the subspecies, G. k. kuroiwae and G. k. orientalis, in the current taxonomic definitions. The marked genetic divergence between populations of the two island groups seems to have initiated in the middle Miocene, i.e., prior to formation of straits that have consistently been separating these two island groups since the early Pleistocene. All populations of G. kuroiwae are regarded as endangered from the viewpoint of conservation genetics.
... Faunistically, the Ryukyu Archipelago is classified into three regions: the Northern, Central, and Southern Ryukyus (Ota, 1998). Of these, the Central Ryukyus, consisting of the Amami and Okinawa Island Groups, are noted for the high abundance of relic species in the non-volant terrestrial fauna, supposedly reflecting its consistent isolation from adjacent land masses even during the periods when the remaining islands of the Ryukyus were connected to adjacent land masses (Ota, 1998(Ota, , 2000Takahashi et al., 2007). ...
Phylogeny and biogeography of the Anderson’s crocodile newt, Echinotriton andersoni (Amphibia: Caudata), as revealed by mitochondrial DNA sequences
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The Anderson's crocodile newt, Echinotriton andersoni, is considered a relic and endangered species distributed in the Central Ryukyus. To elucidate phylogenetic relationships and detailed genetic structures among populations, we analyzed variation in the mitochondrial cytochrome b gene. Results strongly support a primary dichotomy between populations from the Amami and Okinawa Island Groups with substantial genetic divergence, favoring a primary divergence between the two island groups. Within the latter, populations from the southern part of Okinawajima Island are shown to be more closely related to those from Tokashikijima Island than to those from the northern and central parts of Okinawajima. The prominent genetic divergence between the two island groups of the Central Ryukyus seems to have initiated in the Miocene, i.e., prior to formation of the strait that has consistently separated these island groups since the Pleistocene. The ancestor of the southern Okinawajima-Tokashikijima is estimated to have migrated from the northern and central parts of Okinawajima into southern Okinawajima at the Pleistocene, and dispersed into Tokashikijima subsequently.
Historical Biogeography of the Terrestrial Reptiles of Japan: A Comparative Analysis of Geographic Ranges and Molecular Phylogenies
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  • Jan 2017
The geographic ranges and divergence times of Japanese terrestrial reptiles and their close relatives were compared on the basis of recent taxonomic and molecular systematic studies. The comparison of geographic ranges suggested that the Japanese reptile fauna consists of three major biogeographic elements, those of the Southern Ryukyus, the Central Ryukyus, and the Japan Mainland, encompassing taxa endemic to each of these areas. In addition, some interchanges with southern China–Taiwan, Korea–northeastern China–far eastern Russia, and the Pacific islands may also have contributed to the Japanese reptile fauna. The comparison of geographic ranges of related taxa and their divergence times suggested that most of the Southern Ryukyu element was formed by isolation from the fauna of Taiwan and southern China during the Pliocene; the Central Ryukyu element was mostly formed by isolation from the faunas of Taiwan, China, and the Japan Mainland during the late Miocene, in addition to some quite old relict taxa dating back to the Eocene; and the Japan Mainland element was initially formed by isolation from the continental fauna during the middle Miocene, followed by secondary interchange in the Pliocene and Pleistocene.
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A new extinct species of the genus Mauremys (Testudines: Geoemydidae) is described on the basis of three fossils from the late Pleistocene deposit of Tomori Amaga Cave on Miyakojima Island of the Miyako Island Group, Southern Ryukyus, Japan. Of these fossils, two (the anterior half of the plastron and the nuchal) were previously tentatively identified as Mauremys mutica, an extant species whose distribution is currently confined to the Yaeyama Island Group within the Ryukyus. The turtle represented by these two specimens and another, previously unreported material (left third peripheral) actually most resembles M. japonica from mainland Japan and the Northern Ryukyus, and M. yabei from the middle Pleistocene of mainland Japan. The fossil turtle however, differs from the other two in exhibiting a medial length of the entoplastron greater than the interhyoplastron in ventral view, and in having a longitudinal groove medial to the gulo–humeral sulcus on the epiplastron evident in dorsal view. The present finding strengthens endemicity of the recent terrestrial fauna of the Miyako Island Group.
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Abstract. – We provide a first checklist and review of all recognized taxa of the world's extinct Pleistocene and Holocene (Quaternary) turtles and tortoises that existed during the early rise and global expansion of humanity, and most likely went extinct through a combination of earlier hominin (e.g., Homo erectus, H. neanderthalensis) and later human (H. sapiens) exploitation, as well as being affected by concurrent global or regional climatic and habitat changes. This checklist complements the broader listing of all modern and extant turtles and tortoises by the Turtle Taxonomy Working Group (2014). We provide a comprehensive listing of taxonomy, names, synonymies, and stratigraphic distribution of all chelonian taxa that have gone extinct from approximately the boundary between the Late Pliocene and Early Pleistocene, ca. 2.6 million years ago, up through 1500 AD, at the beginning of modern times. We also provide details on modern turtle and tortoise taxa that have gone extinct since 1500 AD. This checklist currently includes 100 fossil turtle and tortoise taxa, including 84 named and apparently distinct species, and 16 additional taxa that appear to represent additional valid species, but are only identified to genus or family. Modern extinct turtles and tortoises include 8 species, 3 subspecies, and 1 unnamed taxon, for 12 taxa. Of the extinct fossil taxa, terrestrial tortoises of the family Testudinidae (including many large-bodied island forms) are the most numerous, with 60 taxa. When the numbers for fossil tortoises are combined with the 61 modern (living and extinct) species of tortoises, of the 121 tortoise species that have existed at some point since the beginning of the Pleistocene, 69 (57.0%) have gone extinct. This likely reflects the high vulnerability of these large and slow terrestrial (often insular) species primarily to human exploitation. The other large-bodied terrestrial turtles, the
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Taxonomic Re-evaluation of the Two Subspecies of Geoemyda spengleri spengleri (Gmelin, 1789) (Reptilia: Emydidae)
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Detailed comparisons are made between Geoemyda spengleri spengleri and G. s. japonica for the first time on the basis of large samples. There are considerable differences between these subspecies, which suggest that both forms should be more ap-propriately treated as independent species. On the other hand, results of comparisons with other closely related species indicate that G. spengleri and G. japonica compose a monophyletic group. The black breasted leaf turtle, Geoemyda spengleri, was first reported without assignment of a definite name by Walbaum (1785), and then was described as Testudo spengleri by Gmelin (1789) on the basis of Walbaum's specimen, pro-bably brought from the East Indies (Pope, 1935). The species has since been reported from southeastern China (Kwangtung, Kwangsi and Hainan Is.), eastern Indochina (Vietnam, Laos and Cambodia), Indo-Australian Archipelago (Batu Islands, Sumatra and Borneo), Philip-pines, and the Ryukyu Archipelago of Japan (Okinawajima Is., Kumejima Is., and Tokashiki-jima Is.) (Rooij, 1915; Wermuth and Mertens, 1977; Toyama, 1985; Iverson, 1986, 1992; Tian et al., 1986). However, records from the Indo-Australian Archipelago and the Philippines have derived only from very old literature descrip-tions (Strauch, 1865; Elera, 1895), and no verifications have been made subsequently. Thus, G. spengleri is considered to be ex-tralimital in these regions (Taylor 1920; Iverson, 1986, 1992). The holotype of G. spengleri was described as lacking axillary and inguinal scutes. Relative lengths of midseams of its plastral shields (plastral formula) can be formulated as ab-dominal>humeral=pectoral=femoral>anal> gular (Walbaum, 1785). Boulenger (1889) noted that the Chinese ones also lack axillary and inguinal, but that their plastral formula is abdominal>femoral>pectoral>humeral>anal >gular. Stejneger (1907) first recorded the species from Japan, and stated that Japanese specimens can be discriminated from Chinese ones described by Boulenger (1889) in having a pair of prominent axillaries and a different plastral formula. Fang (1930) compared the specimens from Kwangsi, China, with those described by Stejneger (1907), and noted that the former differs from the latter in the shape of the cervical, presence of more distinct carapace serra-tion, and absence of spines at the base of the tail. Based on Stejneger's (1907) accounts, Fan (1931) recognized two subspecies with assumption of their distributions as follows: G. spengleri sinen-sis from the continent, and G. s. japonica from Japan and other Pacific islands. He, however, did not refer to the nominotypical form. Further-more, the range of the latter form he listed is ac-tually incorrect (see above). Fang (1934) argued that the plastral formula is highly variable within a population, and that the presence of the ax-illary is probably accidental. He thus suspected that the two subspecies are not separable from each other in reality. These authors, however, did not compare the two forms directly. Pope (1935), after comparing six specimens from the continent and four from the Ryukyus, followed Fan (1931) and considered that the presence or absence of the axillary is a valid discriminant character for the two forms. With the assump-tion that Gmelin's (1789) specimen represents the continental form, he defined the subspecies as follows: G. s. japonica from the Ryukyus, characterized by the prominent axillary and occa-sional trace of the inguinal, and G. s. spengleri from the continent, characterized by the absence of the axillary and inguinal. He further predicted that each of these two forms would be accorded the status of full species after detailed studies are made.