Notes on South American tardigrades with the description of two new species: Pseudechiniscus spinerectus and Macrobiotus danielae

Abstract

Five species of tardigrades from South America are recorded, two of
which, Pseudechiniscus spinerectus and Macrobiotus danielae, are new to science,
and one, Doryphoribius flavus (Iharos 1966), is new for South America.
Pseudechiniscus spinerectus differs from P. bidenticulatus Bartos⁄ 1963 and
P. bartkei Weglarska 1962 by having median plate 2 divided into two portions,
spines of the pseudosegmental plate more developed; it differs from P. bidenticulatus
by having inner claws with a spur; it differs from P. bartkei by having the
caudal portion of the scapular plate faceted, more dense plate sculpture with dot
size increasing from the head to the terminal plate, striae joining the dots to
each other less evident. P. spinerectus differs from P. ramazzottii Maucci 1952
and from P. brevimontanus Kendall-Fite & Nelson 1996 in the following features:
spines of the pseudosegmental plate more developed, dots of plate sculpture
joined to each other by striae. It differs from P. ramazzottii also by having the
papilla of the hind legs clearly shorter; it differs from P. brevimontanus also for
some details of the ventral cuticular sculpture.
Macrobiotus danielae belongs to the richtersi-group; it is very similar to
Macrobiotus vanescens Pilato et al. 1991 from which it differs in the following
features: smaller body size, wider buccal tube, slightly longer microplacoid,
more slender claws, some characters of the eggs (reticular sculpture of the conical
processes with less prominent ridges; less evident apical indentation; basal
areolae smooth).
KEY WORDS: tardigrades, South American fauna, Pseudechiniscus spinerectus n.
sp., Macrobiotus danielae n. sp.