Yamaguchia toyensis
Encyclopedia
Yamaguchia toyensis is one of many aquatic oligochaetes belonging to the family Lumbriculidae
discovered on the island of Hokkaidō
, Japan
, which seems to be one of three "hotspots" of lumbriculid
diversity (the others being the Rocky Mountains
and Lake Baikal
. The genus named after the great oligochaete taxonomist Professor Hideji Yamaguchi.
Y. toyensis was originally collected from profundal parts of Lake Toya
, Hokkaido (after which it is named), and is among the shortest of the lumbriculids (7–11 mm). It is uncertain where in the phylogeny of the lumbriculids Y. toyensis belongs. It seems to lack novel characters with which to place it unambiguously, but has a combination of features not found in other genera of the family: testes and atria in segment X, a single, prosoporous male funnel per atrium, and spermathecae in segment XI.
Lumbriculidae
The Lumbriculidae are a family of microdrile oligochaetes common in fresh-water environments, including streams, lakes, marshes, wells and ground-water. They should not be confused with the earthworm family Lumbricidae. Many species and even genera are highly endemic, mainly in Siberia and the...
discovered on the island of Hokkaidō
Hokkaido
, formerly known as Ezo, Yezo, Yeso, or Yesso, is Japan's second largest island; it is also the largest and northernmost of Japan's 47 prefectural-level subdivisions. The Tsugaru Strait separates Hokkaido from Honshu, although the two islands are connected by the underwater railway Seikan Tunnel...
, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
, which seems to be one of three "hotspots" of lumbriculid
Lumbriculidae
The Lumbriculidae are a family of microdrile oligochaetes common in fresh-water environments, including streams, lakes, marshes, wells and ground-water. They should not be confused with the earthworm family Lumbricidae. Many species and even genera are highly endemic, mainly in Siberia and the...
diversity (the others being the Rocky Mountains
Rocky Mountains
The Rocky Mountains are a major mountain range in western North America. The Rocky Mountains stretch more than from the northernmost part of British Columbia, in western Canada, to New Mexico, in the southwestern United States...
and Lake Baikal
Lake Baikal
Lake Baikal is the world's oldest at 30 million years old and deepest lake with an average depth of 744.4 metres.Located in the south of the Russian region of Siberia, between Irkutsk Oblast to the northwest and the Buryat Republic to the southeast, it is the most voluminous freshwater lake in the...
. The genus named after the great oligochaete taxonomist Professor Hideji Yamaguchi.
Y. toyensis was originally collected from profundal parts of Lake Toya
Lake Toya
is a volcanic caldera lake in Shikotsu-Toya National Park, Abuta District, Hokkaidō, Japan. The stratovolcano of Mount Usu lies on the southern rim of the caldera. The lake is nearly circular, being 10 kilometers in diameter from east-west and 9 kilometers from North-South. The lakes biggest town,...
, Hokkaido (after which it is named), and is among the shortest of the lumbriculids (7–11 mm). It is uncertain where in the phylogeny of the lumbriculids Y. toyensis belongs. It seems to lack novel characters with which to place it unambiguously, but has a combination of features not found in other genera of the family: testes and atria in segment X, a single, prosoporous male funnel per atrium, and spermathecae in segment XI.