Holotype: Pseudatrichum spinosissimum Reimers, Notizbl. Bot. Gart. Berlin 15:401.1941.
Pseudatrichum spinosissimum Reimers is known only from a single locality in
the Chinese province of Kweichow. The only duplicate of the type collection outside
of China was in Berlin, and was destroyed. Consequently, at the present
time I can only speculate concerning this genus and its relationships, based on its
description and its author's comments.
Reimers considered Pseudatrichum to be intermediate between Pogonatum and
Atrichum, because the lamellae in this taxon occupy a portion of the leaf lamina
as well as the nerve, as in some species of Pogonatum [e.g., P proliferum (Griff.)
Mitt.], and the abaxial surface of the lamina bears diagonally oriented tooth
groups as in Atrichum. According to my own assessment of the phylogenetic position
of Atrichum and Pogonatum, any direct relationship between them is highly
unlikely. The leaves of Pseudatrichwn are not bordered as in Atrichum. Reimers
may have overemphasized the resemblance of the abaxial tooth groups of Pseudatrichum
to those of Atrichum. H e admitted that they are "allerdings nicht so
deutlich, wie bei manchen Atrichum-Arten."
Reimers discounted the possibility of relationship between Pseudatrichum and
Oligotrichum, and yet there is a species of the latter in the neighboring province
of Yunnan, Oligotrichum armatum Broth. (Fig. 65), which corresponds rather
closely with the described features of Pseudatrichum. The leaves of the type
specimen of 0. armatum (H!) do not have distinct tooth groups, but do uniformly
exhibit what appear to be the "Zahnandeutungen (kurze doppelschichtige Streifen
der Lamina)" of Pseudatrichum. Considering the extreme variability in the
development of the abaxial lamellae within many Oligotrichum species (e.g.,
0. aligerum Mitt.), it seems best to regard Pseudatrichum spinosissimum as a
provisional synonym of Oligotrichum armatum Broth., until such time as material
is available for comparison.