title: Two new species of Mediomastus (Annelida, Capitellidae) from Tokyo Bay, Japan.
abstract: Two undescribed species of polychaetes in Mediomastus (Annelida: Capitellidae) were collected from intertidal to shallow habitats in Tokyo Bay, Japan. These are M. duobalteus sp. n. and M. hanedaensis sp. n. Mediomastus duobalteus sp. n. is distinguishable from all congeners by the following characters: 1) segments 3, 4, 8-11 stainable with methyl green, 2) thoracic capillary chaetae unilimbate, 3) abdominal capillary chaetae absent, 4) paddle-like chaetae in the thorax absent, and 5) abdominal hooded hooks not flared. Mediomastus hanedaensis sp. n. is similar to M. warrenae Green, 2002, but differs from the latter in the shapes of the thoracic capillary chaetae and the abdominal hooded hooks, and the staining pattern with methyl green. In addition, a key to all Mediomastus species is provided.
authors: Department of Natural History Sciences, Graduate School of Science, Hokkaido University, N10 W8, Sapporo 060-0810, Japan.
authors: Shinri
authors: S
authors: Tomioka
authors: College of Education and Human Sciences, Yokohama National University, Hodogaya, Yokohama 240-8501, Japan.
authors: Eijiroh
authors: E
authors: Nishi
authors: Department of Natural History Sciences, Graduate School of Science, Hokkaido University, N10 W8, Sapporo 060-0810, Japan.
authors: Hiroshi
authors: H
authors: Kajihara
keywords: Pacific; Taxonomy; morphology; polychaete