The Okada's five-lined skink or Far Eastern skink (''Plestiodon latiscutatus'', Jap. オカダトカゲ ''Okada-Tokage'') is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

lizard Lizard is the common name used for all Squamata, squamate reptiles other than snakes (and to a lesser extent amphisbaenians), encompassing over 7,000 species, ranging across all continents except Antarctica, as well as most Island#Oceanic isla ...

which is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

Taxonomy

The species was first described by the American herpetologist Edward Hallowell in 1861. There are no recognized subspecies. During the 20th century it was placed in the genus ''

Eumeces The genus ''Eumeces'' (family (biology), family Scincidae) comprises four African to Middle-Eastern skink species. Systematics Recently two taxonomic revisions have been made regarding the 19th century genus ''Eumeces''. They both resulted in si ...

'' which now contains

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

n and

Middle-Eastern The Middle East (term originally coined in English language) is a geopolitical region encompassing the Arabian Peninsula, the Levant, Turkey, Egypt, Iran, and Iraq. The term came into widespread usage by the United Kingdom and western Eur ...

skinks. It was long named ''Eumeces okadae'' but changed to ''latiscutatus'' according to the rules of nomenclature and priority.

Description

The total length is between 15 and 24 cm and the snout-vent length 60 to 96 mm.Richard C. Goris, Norio Maeda: ''Guide to the Amphibians and Reptiles of Japan'', Krieger Publishing Company, 2004, ISBN 1575240858 (p. 165–167) Similar species are '' P. japonicus'' and '' P. finitimus''. The color of ''P. latiscutatus'' is more greenish than for ''P. japonicus''. Juveniles have a blue tail which is also more greenish than for ''P. japonicus'' and the striped pattern of ''P. latiscutatus'' disappears sooner. On the outer Izu islands the skinks usually have more rows of body scales than ''P. japonicus''. Overall the species are best distinguished by their geographic range.

Behavior

It preys on earthworms, spiders, ants,

Amphipoda Amphipoda () is an order (biology), order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods () range in size from and are mostly detritivores or scavengers. There are more than 10,700 amphip ...

and other invertebrates. The mating season is in spring from mid-April to late May. Females lay clutches of four to twelve eggs every two years. The size of the clutches varies from island to island with a higher number of eggs per clutch on islands with low population densities of the species. The females care for the eggs until they hatch as all Japanese species of ''Plestiodon''. While remaining with the eggs, the females roll them about in the nest. Experiments where the females were instead removed from their nests showed that the eggs usually didn't survive.

Geographic range and threats

It is found on the

Izu Islands The are a group of volcanic islands stretching south and east from the Izu Peninsula of Honshū, Japan. Administratively, they form two towns and six villages; all part of Tokyo Prefecture. The largest is Izu Ōshima, usually called simply Ōsh ...

and the

Izu Peninsula The is a mountainous peninsula with a deeply indented coastline to the west of Tokyo on the Pacific Ocean, Pacific coast of the island of Honshu, Japan, the largest of the four main islands of Japan. Formerly known as Izu Province, Izu peninsu ...

. The

IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...

lists the species as least concern. However, some subpopulations on the Izu islands

Miyake-jima is a Volcano, volcanic island in the Izu Islands, Izu archipelago in the Philippine Sea approximately southeast of Tokyo, Japan. As with the other islands in the Izu Island group, Miyake-jima forms part of the Fuji-Hakone-Izu National Park. ...

Hachijō-jima is a volcano, volcanic Islands of Japan, Japanese island in the Philippine Sea. It is about south of the special wards of Tokyo. It is part of the Izu Islands, Izu archipelago and within the Fuji-Hakone-Izu National Park. Its only municipalit ...

and

Aogashima is a volcanic island to the south of Japan in northernmost Micronesia. It is the southernmost and most isolated inhabited island of the Izu Islands. The islands border the northeast Philippine Sea and lie north of the Ogasawara Islands. Nussba ...

have been in decline due to the introduction of

Japanese weasel The Japanese weasel (''Mustela itatsi'') is a carnivorous mammal belonging to the genus '' Mustela'' in the family Mustelidae. The most closely related ''Mustela'' species is the Siberian weasel (''Mustela sibirica''). Its taxonomic species name, ...

s as a predator species in order to control rats. There is also hybridization on Hachijō-jima with introduced ''P. japonicus''. On the

Japanese Red List The Japanese is the Japanese domestic counterpart to the IUCN Red List of Threatened Species. The national Red List is compiled and maintained by the Ministry of the Environment, alongside a separate Red List for marine organisms. Similarly draw ...

the species is therefore listed as species with ''Locally endangered Population'' on these three islands. The majority population on the Izu Peninsula is considered as stable. The ranges of two ''Plestiodon'' species border ''P. latiscutatus'': ''P. japonicus'' is found in southwestern

Honshū , historically known as , is the largest of the four main islands of Japan. It lies between the Pacific Ocean (east) and the Sea of Japan (west). It is the seventh-largest island in the world, and the second-most populous after the Indonesian ...

with the exception of the Izu Peninsula and on

Shikoku is the smallest of the List of islands of Japan#Main islands, four main islands of Japan. It is long and between at its widest. It has a population of 3.8 million, the least populated of Japan's four main islands. It is south of Honshu ...

and

Kyushu is the third-largest island of Japan's Japanese archipelago, four main islands and the most southerly of the four largest islands (i.e. excluding Okinawa Island, Okinawa and the other Ryukyu Islands, Ryukyu (''Nansei'') Ryukyu Islands, Islands ...

as well as surrounding islands. On the Izu Islands ''P. japonicus'' is only found on Hachijō-jima, where it was introduced. ''P. finitimus'' is dirstributed north to ''P. latiscutatus'' on Honshū and

Hokkaido is the list of islands of Japan by area, second-largest island of Japan and comprises the largest and northernmost prefectures of Japan, prefecture, making up its own list of regions of Japan, region. The Tsugaru Strait separates Hokkaidō fr ...

. The species border runs in the northwest of the Izu Peninsula along the lower

Fuji River The is a river in Yamanashi Prefecture, Yamanashi and Shizuoka Prefectures of central Japan. It is long and has a drainage basin, watershed of . With the Mogami River and the Kuma River (Japan), Kuma River, it is regarded as one of the three mos ...

which is located southwest of Fuji-san. On the northeastern side of Izu Peninsula and southeast of Fuji-san it runs along

Sakawa River The is a river in Shizuoka Prefecture and Kanagawa Prefecture Japan. In Shizuoka Prefecture it is called the Ayuzawa River. It flows into the Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the ocean ...

. This coincides with a former sea that is assumed to have separated the Izu Peninsula which is located on the

Philippine Sea Plate The Philippine Sea plate or the Philippine plate is a tectonic plate comprising oceanic lithosphere that lies beneath the Philippine Sea, to the east of the Philippines. Most segments of the Philippines, including northern Luzon, are part of ...

from the rest of modern-day Honshū until the mid-

Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...

. Similar biogeographic borders exist for the

woodlouse Woodlice are terrestrial isopods in the suborder Oniscidea. Their name is derived from being often found in old wood, and from louse, a parasitic insect, although woodlice are neither parasitic nor insects. Woodlice evolved from marine isopods ...

species ''

Ligia oceanica ''Ligia oceanica'', the sea slater, common sea slater, or sea roach, is a woodlouse, living in the littoral zone—rocky seashores of the European North Sea and Atlantic coastlines. ''L. oceanica'' is oval, twice as long as broad, and may reach ...

'' and for land-snails. The three ''Plestiodon'' species only overlap in a small range and show clear differences in mitochondrial DNA sequence.Okamoto, Taku; Motokawa, Junko; Toda, Mamoru; Hikida, Tsutomu 2006. ''Parapatric distribution of the lizards Plestiodon (formerly Eumeces) latiscutatus and P. japonicus (Reptilia: Scincidae) around the Izu Peninsula, central Japan, and its biogeographic implications.'' Zoological Science 23:419– 425 doi:10.2108/zsj.23.419 Other species of the genus found in Japan are distributed on the

Nansei Islands The , also known as the or the , are a chain of Japanese islands that stretch southwest from Kyushu to Taiwan: the Ryukyu Islands are divided into the Satsunan Islands ( Ōsumi, Tokara and Amami) and Okinawa Prefecture ( Daitō, Miyako, Y ...

: * '' P. barbouri'' on

Amami Islands The The name ''Amami-guntō'' was standardized on February 15, 2010. Prior to that, another name, ''Amami shotō'' (奄美諸島), was also used. is a Japanese archipelago in the Satsunan Islands, which is part of the Ryukyu Islands, and is sout ...

and

Okinawa Islands The are an island group in Okinawa Prefecture, Japan, and are the principal island group of the prefecture. The Okinawa Islands are part of the larger Ryukyu Islands group and are located between the Amami Islands of Kagoshima Prefecture to the ...

* '' P. elegans'' on

Senkaku Islands The Senkaku Islands, known as the Diaoyu Islands in China and the Tiaoyutai Islands in Taiwan, are a group of uninhabited islands in the East China Sea, administered by Japan. They were historically known in the Western world as the Pinnacle ...

and Taiwan, Southeast-China and North-Vietnam * '' P. kishinouyei'' on Miyako and

Yaeyama Islands The Yaeyama Islands (八重山列島 ''Yaeyama-rettō'', also 八重山諸島 ''Yaeyama-shotō'', Yaeyama: ''Yaima'', Yonaguni: ''Daama'', Okinawan: ''Yeema'', Northern Ryukyuan: ''Yapema'') are an archipelago in the southwest of Okinawa Pref ...

* '' P. kuchinoshimensis'' auf

Kuchinoshima , literally "mouth island", is one of the Tokara Islands, belonging to Kagoshima Prefecture. The island, in area, and has a population of 140 persons. The island can only be reached by boat as it has no airport; there is regular ferry service to ...

in the northern

Tokara Islands The is an archipelago in the Nansei Islands, and are part of the Satsunan Islands, which is in turn part of the Ryukyu Archipelago. The chain consists of twelve small islands located between Yakushima and Amami-Oshima. The islands have a total ...

* '' P. marginatus'' on Okinawa, Amami and Tokara Islands * '' P. oshimensis'' on Amami and Tokara Islands * '' P. stimpsonii'' on Yaeyama Islands * '' P. takarai'' on four of the

References

{{Taxonbar, from=Q3392329 latiscutatus Endemic reptiles of Japan Reptiles described in 1861 Taxa named by Edward Hallowell (herpetologist)