Molecular and morphological analysis of an Antarctic tardigrade, Acutuncus antarcticus

• Published in: Journal of Limnology
• Main Authors: Hiroshi Kagoshima, Satoshi Imura, Atsushi C. Suzuki
• Format: Article in Journal/Newspaper
• Language: English
• Published: PAGEPress Publications 2013
• Subjects: Tardigrada; antarctica; cultivation; exuviae; JARE (Japanese Antarctic Research Expedition); 18S rRNA; geo; Antarctic; Hotoke Ike; King George Island; Langhovde; Skarvsnes; South Shetland Islands; Syowa Station; Acutuncus antarcticus; Antarc*; Antarctica; antarcticus; Tardigrade
• Online Access: https://doi.org/10.4081/jlimnol.2013.s1.e3; https://doaj.org/article/132d3ebeae094011908f2a40381a6999

We isolated a species of tardigrade from moss samples collected from Langhovde and Skarvsnes, near Syowa station, East Antarctic, from which we cultured a parthenogenetic strain in Petri dishes with co-occurring cyanobacteria or green algae. This culture was maintained at both 4 and 10ºC, though the latter proved more suitable for growth. Eggs were laid free, rather than in exuviae. We isolated the 18S rRNA sequences from this tardigrade, identical to that of Acutuncus antarcticus from King George island, South Shetland islands. Morphological analyses via both light and scanning electron microscopy also show general agreement with characteristics of A. antarcticus: dorsal and ventral apophyses for the insertion of stylet muscles and dorsal longitudinal thickening on the anterior part of buccal tube; presence of pharyngeal apophyses, two macroplacoids and absence of a microplacoid; the surface structure of egg; and claw shape. Peribuccal lamellae were absent, but six oval swellings surrounded the mouth opening. An additional study of moss pillars from lake Hotoke-ike, Skarvsnes, proved the existence of the same tardigrade taxon living at the bottom of the lake.