''Asterias versicolor'' is a species of

starfish Starfish or sea stars are star-shaped echinoderms belonging to the class Asteroidea (). Common usage frequently finds these names being also applied to ophiuroids, which are correctly referred to as brittle stars or basket stars. Starfish ...

native to the southern coasts of

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

southwards to the

South China Sea The South China Sea is a marginal sea of the Western Pacific Ocean. It is bounded in the north by the shores of South China (hence the name), in the west by the Indochinese Peninsula, in the east by the islands of Taiwan and northwestern Phil ...

Taxonomy

The species was first described by

Percy Sladen Walter Percy Sladen (30 June 1849 – 11 June 1900) was an English biologist who specialised in starfish. The son of a wealthy leather merchant, Sladen was born near Halifax, Yorkshire on 30 June 1849. He was educated at Hipperholme Grammar Sc ...

in 1889. Sladen does not specify the etymology of the

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

, but states the mottled yellow and dark brown colouration is striking, and likely derived the name from this observation. In 1930

Walter Kenrick Fisher Walter Kenrick Fisher (February 1, 1878 – November 2, 1953) was an American zoologist, evolutionary biologist, illustrator and painter. He taught in Stanford University before eventually becoming Emeritus Professor in Zoology until his retireme ...

stated that ''Asterias versicolor'' was closely related to ''A. amurensis'', but that ''A. rollestoni'' might well intergrade with this species to the north of its range. In the same publication Fisher reduced ''A. rollestoni'' to a ''forma'' of ''A. amurensis''. In 1936 Ryori Hayashi published an account of the species and stated his doubts regarding its distinctiveness compared with ''A. amurensis'', and in the 1940 article ''Contributions to the Classification of the Sea-stars of Japan'' Hayashi went through with his suggestion and reduced ''A. versicolor'' to a form of ''A. amurensis'', as ''A. amurensis'' f. ''versicolor'', considering it to be most similar to ''A. rollestoni'' -he ascribed to Fisher's classification of this taxon as ''A. amurensis'' f. ''rollestoni''. This classification is still used in Japan (as a

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

, ''A. amurensis'' ssp. ''versicolor''). Alexander Michailovitsch Djakonov in 1950 cites Hayashi's 1936 work in his account of the species, instead of the main 1940 work cited elsewhere in his references, and he was unable to measure specimens personally, so it is somewhat unclear if Djakonov truly rejected Hayashi's classification.

Description

This starfish has five arms. The disc is robust, convex and with a

radius In classical geometry, a radius ( : radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', meaning ray but also the ...

of up to 1.7-1.9cm across. The underside of the animal is flat, and the margin (edge) of especially the arms is sharply angular. It has an arm length to 6.2, 7.1 or 8.2cm, the width of the base of the arm being to 2.2cm; the ratio between the length of the arm and the radius of its disc is 4:1, to slightly more. Fisher states the general colour is yellowish mottled with brown, and implies the smaller immature specimens are mottled dark and light brown. Hayashi specifies the yellowish mottled with brown colouration is in dried museum specimens. Sladen specifies that when the specimens are preserved in alcohol the colouration is bleached yellowish-white on the underside and bleached yellowish-white mottled with dark chocolate brown on the topside. There is a single spine arising from each patch of yellowish skin, with the dark brown patches being in the spineless areas in between. The dorsal (carinal) spines are small but robust, 1-1.2mm long, end in a truncated, sometimes channelled or otherwise crenellated point, and are arranged in a rough stripe down the top of each arm. These spines are affixed to the dorsal plates of the

exoskeleton An exoskeleton (from Greek ''éxō'' "outer" and ''skeletós'' "skeleton") is an external skeleton that supports and protects an animal's body, in contrast to an internal skeleton (endoskeleton) in for example, a human. In usage, some of the ...

, and on the skin appear to occupy the centre of a low, broad, slightly convex bump. The dorsolateral spines are somewhat larger and widely spaced. The marginal spines are even wider spaced and somewhat larger, 1.7-2mm long, and the plates below the margin bear two shorter, robust spines each. The straight

pedicellariae A pedicellaria (plural: pedicellariae) is a small wrench- or claw-shaped appendage with movable jaws, called valves, commonly found on echinoderms (phylum Echinodermata), particularly in sea stars (class Asteroidea) and sea urchins (class Echinoi ...

are relatively small, slender, 0.2–0.22mm long, and scattered over the dorsal surface. The crossed (forcipiform) pedicellariae are also slender, and clustered in wreaths or circles around the bases of the dorsal to the marginal spines. It has

planktonic Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucia ...

larvae. Juveniles have the same spination as the adults on the top of the disc, but gradually grow more spines towards the margin as they increase in size. The size of the spines which are present appear relatively larger than those of adults. The margins of the arms are less sharply angular. When the arms reach 1.5cm in length the final adult spines appear, the double spines below the margin. When the starfish grows slightly larger the position of the spines shift into a fully adult formation.

Similar species

Sladen considered it a close ally of ''

Asterias amurensis ''Asterias amurensis'', also known as the Northern Pacific seastar and Japanese common starfish, is a seastar found in shallow seas and estuary, estuaries, native to the coasts of northern China, Korea, far eastern Russia, Japan, Alaska, the Aleu ...

'', being separated from this species by the spines on the plates below the margin and the character of the armature. Verrill and Hayashi find it is the most similar to ''A. rollestoni''; according to Verrill differing from this species by having less spines and shorter and blunter pedicellaria; Hayashi pointing to the somewhat more robust skeleton, the single spine per dorsal plate, and the smaller and more slender pedicellaria. Fisher agrees with both views, noting it is "obviously related" to ''A. amurensis'' and possibly conspecific with ''A. rollestoni'' (a form of ''A. amurensis'' according to him), but "perfectly distinct from both".

Distribution

The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

was collected in the sea off

Kobe Kobe ( , ; officially , ) is the capital city of Hyōgo Prefecture Japan. With a population around 1.5 million, Kobe is Japan's seventh-largest city and the third-largest port city after Tokyo and Yokohama. It is located in Kansai region, whic ...

by the 1873–1876 scientific expedition by the H.M.S. Challenger, these waters having depths of 8–50 fathoms according to Sladen in 1889, from which Djakonov derived his depth range of 14.5 to 91.5m for the species in 1950. It is native to the southern coasts of

including

Toyama Bay is a bay located on the northern shores of the Hokuriku region of Honshu, Japan on the Sea of Japan. The bay borders Toyama and Ishikawa prefectures. The bay is known for the mirages on the horizon during the winter months and for being a spaw ...

and the

Seto Inland Sea The , sometimes shortened to the Inland Sea, is the body of water separating Honshū, Shikoku, and Kyūshū, three of the four main islands of Japan. It serves as a waterway connecting the Pacific Ocean to the Sea of Japan. It connects to Osaka ...

, and has also been found southwards to north

Taiwan Taiwan, officially the Republic of China (ROC), is a country in East Asia, at the junction of the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the nort ...

, around

Hong Kong Hong Kong ( (US) or (UK); , ), officially the Hong Kong Special Administrative Region of the People's Republic of China ( abbr. Hong Kong SAR or HKSAR), is a city and special administrative region of China on the eastern Pearl River Delt ...

and in the

. It was first recovered on seabeds with mud and sand substrates.

References

{{Taxonbar, from=Q2373584 versicolor Taxa named by Percy Sladen Animals described in 1889