Hennediella is a somewhat puzzling genus which had been previously
included in various genera, such as Desmatodon, Pottia, Syntrichia,
and Tortula. It was re-defined by Zander (1993) who distinguished 20
species, with a distributional center mainly in the southern
hemisphere. Due to uncertain boundaries concerning characters, the
recognised taxa, however, often integrade somewhat and the
deliminations given still are unsatisfying. Especially the
deliminations against Tortula and Syntrichia still remain difficult,
and without a world-wide revision of especially Tortula,
problematical. Main characters used at present are KOH colour leaf
reactions [orange to red in Hennediella and Syntrichia versus yellow
(rarely orange) in Tortula] and anatomy of the costa [stereids
semicircular in Hennediella, lunulate in Syntrichia and (semicircular)
circular in Tortula]. Aim of the present revision therefore is to
provide a comprehensive taxonomic synthesis of the species currently
placed within the genus Hennediella.
The revision is based on extensive field studies and new collections
from South America, as well as the analysis of more than 1100
specimens from 49 institutional and three private herbaria all over
the world. 226 of them were used as ‘operational taxonomic units’
(species groups) for a morphometrical analysis, where 54 quantitative
characters were measured to test the most significant
characters. Unfortunately, the data matrix used is not given and only
available upon request by the author. To save printing costs, this is
meanwhile very common, but the basic data of the study thus are
lacking. This holds true for the full list of studied specimens,
which, however, is available on the web (www.pottiaceae.com).
As a result, 17 taxa (15 species, two varieties: H. antarctica,
H. arenae var. arenae, H. arenae var. petriei, H. bellii,
H. densifolia, H. denticulata, H. heimii, H. heteroloma var. eckeliae,
H. heteroloma var. heteroloma, H. kunzeana, H. longipedunculata,
H. longirostris, H. macrophylla, H. marginata, H. polyseta,
H. stanfordensis, H. steereana) were presented, based on morphological
similarities. 37 names are lectotypified, and two epitypes
designated. Hennediella acletoi is synonymysed with H. denticulata,
and Tortula leiostomoides with H. longirostris. The former
H. angustifolia and H. serrulata are transferred to the genus
Syntrichia, and Desmatodon spelaeus, H. oedipodioides, Pottia
chubutensis, and Syntrichia astoma are synonymyzed with H. heimii,
H. acutidenta and P. fusco-mucronata with H. antarctica.
After a short historical review of the taxonomy and nomenclature of
‘Hennediella’, the study continues with the deliminations of the
genus, ‘material & methods’, the taxonomic characters used, the
results of the morphometric analysis [14 box plots, two scatterplots
(PCA, DA) of the H. heimii-antarctica group] and some short remarks on
the habitat and distribution (including a diagramm of the altitude
variation in the genus). 14 of the 15 species recognized occur in the
southern hemisphere. Chapter ‘Taxonomy’ comprises the main part of
the book, starting with a key to 15 species. The following 89 pages
provide a detailed description of all taxa, including synonymy,
distributional remarks, and illustrations (line drawings, LM and SEM
photos of leaf surface, cross-section of the leaf and costa,
peristome, and spores). The species descriptions are very detailled
and instructive and the line drawings and photos given are superbly
and of high quality. They show the main diagnostic characters. A list
of selected specimens examined, a hint to additional illustrations, as
well as a well stated discussion completes each description. The study
ends with doubtful, excluded and invalid names and a list of
references.
The revision is a well-done, well based and solid study. The taxonomic
treatment, even if geographically mainly restricted to the southern
hemisphere is very useful for identyfing species and a further step
towards lightening and understanding one of the most prominent and
difficult families (Pottiaceae) in bryology.
H. KÜRSCHNER, Berlin
Nova Hedwigia 87/3-4 (November 2008)
