Sharon E. Bartholomew-Began:

A morphogenetic re-evaluation of Haplomitrium Nees (Hepatophyta)

1991. 297 pages, 11 tables, 508 fig. on 187 p. as app., 14x22cm, 870 g
Language: English

(Bryophytorum Bibliotheca, Band 41)

ISBN 978-3-443-62013-4, paperback, price: 112.00 €

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Synopsis top ↑

The hepatic genus Haplomitrium has traditionally been of great phylogenetic interest due to its wide array of presumed ancestral characters, some of which are unique and others of which are reminiscent of Takakia and other bryophyte groups. However, the evolutionary affinities, taxonomy, and underlying morphogenetic patterns of Haplomitrium remain uncertain. Of the 13 described species, only 5 have been studied, in part, for developmental patterns, mostly at the light microsc0pe level. New discoveries of both unique and moss-like ultrastructural characters in Takakia, a postulated close relative of Haplomitrium, and recent suggestions that Haplomitrium is more closely related to the Metzgeriales than to the Jungermanniales makes renewed investigations, including ultrastructural analyses of Haplomitrium appropriate. In this study, the ontogenetic patterns responsible for morphological features of the genus were investigated using experimental culture techniques, light and electron microscopy. Morphogenetic potentials were examined to gain insight into both infrageneric affinities and the phylogenetic relationships with other bryophyte groups, Takakia and the tracheophytes. Of the 13 species studied, 7 are retained and 6 new synonyms are proposed. Likewise, the only other extant member of the Haplomitriales, Steereomitrium, was synonymized with Haplomitrium. The taxa are grouped into two subgenera: subg. Haplomitrium (with two sections: sect. Haplomitrium and sect. Archibryum) and subg. Calobryum. It is concluded that, the genus is a highly plastic, plesiomorphic taxon, probably of Gondwanian origin. Haplomitrium's assemblage of derived traits negate it as the progenitor of either the Metzgeriales or the Jungermanniales. Rather, it appears to have a shared ancestry with the Metzgeriales, and is consequently best classified as a coordinate order in the newly described subclass Metzgeriidae. The shared ancestry of the Haplomitriales and the Metzgeriales suggests that primal hepatics were cylindrical forms with the potential to give rise independently to both dorsiventral and erect, radial gametophytes in response to selective pressures.

Contents top ↑

Specimens Examined 15
Culture Techniques 15
Light Microscopy Techniques 16
Electron Microscopy Techniques 17
Experimental Techniques 18
The Vegetative Gametophyte 21
Gross Morphology 21
Haplomitrium hooker) (Smith) Nees 24
Haplomitrium ovalifolium Schust. 26
Haplomitrium monoicum Engel 27
Haplomitrium intermedium Berrie 28
Hapiomitrium gibbsiae (Steph.) Schust. 31
Haplomitrium kashyapii Udar & Kumar 33
Haplomitrium mnioides (Lindb.) Schust. 35
Haplomitrium blumii (Nees) Schust. 36
Haplomitrium andinum (Spruce) Schust. 37
Apical Organization 39
Stem Development and Anatomy 51
Leaf Development and Anatomy 63
Oil Bodies 68
Branching 80
The Reproductive Gametophyte 85
Gross Morphology 85
Haplomitrium hooker) (Smith) Nees 86
Haplomitrium ovalifolium Schust. 93
Haplomitrium monoicum Engel 94
Haplomitrium intermedium Berrie 95
Haplomitrium gibbsiae (Steph.) Schust. 96
Haplomitrium indicum (Udar &
Chandra) Schust. 99
Haplomitrium dentatum (Kumar & Udar) Engel 100
Haplomitrium grollei Kumar & Udar 102
Haplomitrium kashyspii Udar & Kumar 103
Haplomitrium mnioides (Lindb.) Schust. 106
Haplomitrium blumii (Nees) Schust. 108
Haplomitrium andinum (Spruce) Schust. 109
Haplomitrium giganteum (Steph.) Grolle 111
Steereomitrium minutum E. O. Campb. 112
Antheridial Ontogeny 118
Structure of the Antheridium 124
Archegonial Ontogeny 135
Structure of the Archegonium 140
Sporophyte Protective Structure 142
The Sporophyte 156
Gross Morphology 156
Anatomy and Ontogeny 157
Elaters 166
Haplomitrium hookeri (Smith) Nees 167
Haplomitrium intermedium Berrie 168
Haplomitrium gibbsiae (Steph.) Schust. 168
Haplomitrium indicum Udar &
Chandra) Schust. 169
Haplomitrium mnioides (Lindb.) Schust. 169
Haplomitrium blumii (Nees) Schust. 169
Haplomitrium andinum (Spruce) Schust. 169
Steereomitrium minutum E. O. Campb. 170
Spores 170
Haplomitrium hooker) (Smith) Nees 173
Steereomitrium minutum E. O. Campb. 173
Haplomitrium mnioides (Lindb.) Schust. 174
Haplomitrium gibbsiae (Steph.) Schust. 174
Haplomitrium indicum (Udar &
Chandra) Schust. 176
Haplomitrium dentatum (Kumar & Udar) Engel 176
Haplomitrium intermedium Berrie 176
Haplomitrium blumii (Nees) Schust. 177
Haplomitrium andinum (Spruce) Schust. 177
Capsule Dehiscence 180
Sporeling Development 183
Ontogenetic Pattern 183
Pattern Comparisons and Phylogenetic
Implications 189
Experimental and Culture Studies 194
Spore Culture Experiments 194
Culture-Induced Adult Phenovariations 204
Metzgeriidae Bartholomew-Began 212
Haplomitriales Buch ex Schljakov 213
Haplomitriaceae Dedecek 214
Haplomitrium Nees 216
Structural Features Useful for Subgeneric
and Interspecific Differentiation 220
Subdivision of the Genus and Relationships
Among Taxa 222
Keys to the Taxa of Haplomitrium 224
Key to the Subgenera and Sections of
Haplomitrium 224
Key to the Species of the Subgenus
Haplomitrium section Haplomitrium 224
Key to the Species of the Subgenus
Haplomitrium section Archibryum 225
Key to the Species of the Subgenus
Calobryum 226
Vegetative Key to the Species
of Haplomitrium 226
Subgenus Haplomitrium 227
Subg. Haplomitrium sect. Haplomitrium 227
H. hookeri (Smith) Nees 228
H. hookeri var. hooker) 229
H. hookeri (Smith) Nees var. minutum
(E. O. Campb.) Bartholomew-Began 230
H. ovalifolium Schust. 234
H. monoicum Engel 236
Subg. Haplomitrium sect. Archibryum
(Schuss.) Engel emend. Bartholomew-Began 238
H. intermedium Berrie 238
H. gibbsiae (Steph.) Schust. 240
Subg. Calobryum (Nees) Schust. 247
H. mnioides (Lindb.) Schust. 247
H. blumii (Nees) Schust. 250