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Vol. 54, 2015
The genus Milnesium
Doyère, 1840 (Tardigrada) in South America with descriptions of two new
species from Argentina and discussion of the feeding behaviour in the
family Milnesiidae
Milena Roszkowska1,2,*,
Marta Ostrowska1,
and Łukasz Kaczmarek1,2
1Department
of Animal Taxonomy and Ecology, Faculty of Biology, Adam Mickiewicz
University in Poznań, Umultowska 89, 61-614, Poznań, Poland
2Laboratorio
de Ecología Natural y Aplicada de Invertebrados, Universidad Estatal
Amazónica, Campus Principal Km 2.1/2 via a Napo (Paso Lateral) Puyo,
Pastaza, Ecuador
Abstract
Background: The diversity and
distribution of the tardigrades in South America are rather poor and
selective, as is information about their feeding behaviour and diet. To
date, only ca. 210 tardigrade taxa have been reported from the region
of South America. In the present paper, we provide an update of the
distribution of the genus Milnesium
in South America and discuss some aspects of the feeding behaviour in
the family Milnesiidae.
Results: In seven moss samples collected in the
Argentinean province of Río Negro, 31 specimens, 4 exuviae and 32 eggs
belonging to the genus Milnesium
were found. Among them, four species were identified: Milnesium argentinum sp. nov., Milnesium beatae sp. nov., Milnesium brachyungue and Milnesium granulatum. By its dorsal
sculpture, M. argentinum sp.
nov. is most similar to M. beatae
sp. nov., Milnesium beasleyi
and Milnesium berladnicorum,
but it differs from M. beasleyi
and M. berladnicorum mainly
by having a different claw configuration and from M. beatae and M. beasleyi by having stylet
supports inserted in a more caudal position and by some other
morphometric characters. In the width of its buccal tube and the claw
configuration [3-3]-[3-3], M. beatae
sp. nov. is most similar to Milnesium
bohleberi, M. brachyungue
and Milnesium eurystomum, but
it differs from themmainly by having a sculptured dorsal cuticle and by
some other morphometric characters.
Conclusions: The study discusses
distribution and taxonomic problems of the Milnesium species known from South
America. As of now, nine Milnesium
taxa are known from this region (including two new species reported in
this paper). Additionally, the study broadens our knowledge of
tardigrades' feeding behaviour, provides some details about their diet
and suggests that the type of prey chosen by some species belonging to
the family Milnesiidae may be associated with the width of their buccal
tube.
Key words:
Milnesiidae; Milnesium argentinum sp. nov; Milnesium beatae sp. nov;
Nahuel Huapi National Park; Neotropical region; New records; Prey
selection; Río Negro; Taxonomy; Water bears.
*Correspondence: E-mail: mil.roszkowska@gmail.com
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