Christensenia , a new terrestrial enchytraeid genus from Antarctica

Christensenia gen. nov., C. blocki sp. nov., is described from Signy Island, South Orkney Islands, maritime Antarctic. The new species is identical with specimens that Stephenson (1932) determined as Marionina georgiana (Michaelsen, 1888), but differs from the type material of M. georgiana. The spec...

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Bibliographic Details
Published in:Polar Biology
Main Authors: Dózsa-Farkas, K., Convey, P.
Format: Article in Journal/Newspaper
Language:unknown
Published: Springer 1997
Subjects:
Antarctic
South Orkney Islands
Signy Island
Stephenson
Antarc*
Antarctica
Polar Biology
Online Access:http://nora.nerc.ac.uk/id/eprint/514458/
https://doi.org/10.1007/s003000050146
Description
Summary:Christensenia gen. nov., C. blocki sp. nov., is described from Signy Island, South Orkney Islands, maritime Antarctic. The new species is identical with specimens that Stephenson (1932) determined as Marionina georgiana (Michaelsen, 1888), but differs from the type material of M. georgiana. The species M. georgiana (Michaelsen, 1888) is also placed in the new genus Christensenia, the main characteristics of which are: possession of sigmoid setae, and the presence of large numbers of small, hyaline, stick-like, anucleate lymphocytes. No other types of lymphocyte are observed. Oesophageal appendages and intestinal diverticulae are absent. Dorsal vessel originates in the clitellar region; blood is colourless. The anteseptal part of the nephridium consists of the funnel and a few canals, with the efferent duct arising postero-ventrally. Spermathecae are without diverticulae, entally connecting with the oesophagus. The known distribution of the genus is currently limited to terrestrial habitats in the sub- and maritime Antarctic.

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