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A new species of Brevianthus (Brevianthaceae, Marchantiophyta) from New Caledonia with unusual underleaf production.

Renner MA, Engel JJ, Patzak SD, Heinrichs J - PhytoKeys (2015)

Bottom Line: A second species, Brevianthushypocanthidium, is described as new and is the first record of the genus for New Caledonia.Among its distinguishing characters are its shallowly bilobed leaves, and triangular underleaves present on small to medium-sized shoot sectors, the lack of a hyaline leaf margin, and the crenulate leaf margin formed by heavily thickened external cell walls.To explain these features we propose a competitive model of shoot formation wherein the ventral merophyte progressively loses vigor as its relative stature decreases, and its derivative cells become discontinuous and isolated along the ventral stem surface, with intervening areas occupied by derivatives of the more vigorous lateral merophytes.

View Article: PubMed Central - PubMed

Affiliation: Royal Botanic Gardens & Domain Trust, Mrs Macquaries Road, Sydney, NSW 2000, Australia.

ABSTRACT
Brevianthus is a distinctive genus of leafy liverwort in its succubously inserted, entire leaves, lack of underleaves, restriction of sexual organs to lateral-intercalary branches, scattered rhizoids and dense leaf-surface ornamentation. The sole species, Brevianthusflavus, is divided into two subspecies, one in Tasmania the other in New Zealand. A second species, Brevianthushypocanthidium, is described as new and is the first record of the genus for New Caledonia. Among its distinguishing characters are its shallowly bilobed leaves, and triangular underleaves present on small to medium-sized shoot sectors, the lack of a hyaline leaf margin, and the crenulate leaf margin formed by heavily thickened external cell walls. The most unusual features of the new species are the presence of underleaves between lateral leaf insertion lines that reach the ventral stem mid-line, and the absence of underleaves from larger shoots. To explain these features we propose a competitive model of shoot formation wherein the ventral merophyte progressively loses vigor as its relative stature decreases, and its derivative cells become discontinuous and isolated along the ventral stem surface, with intervening areas occupied by derivatives of the more vigorous lateral merophytes.

No MeSH data available.


Related in: MedlinePlus

Brevianthusflavussubsp.crenulatus: A leaf apex B cells below apex on abaxial leaf surface C, D abaxial leaf surface at mid-leaf E, F adaxial leaf surface. All from NSW745726. Scale: 20 µm (A, B, E, F); 10 µm (C, D).
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Figure 6: Brevianthusflavussubsp.crenulatus: A leaf apex B cells below apex on abaxial leaf surface C, D abaxial leaf surface at mid-leaf E, F adaxial leaf surface. All from NSW745726. Scale: 20 µm (A, B, E, F); 10 µm (C, D).

Mentions: Leaf surface ornamentation may exhibit species-specific differences though there is intra-individual variation; our interpretation, however, may suffer from the relatively small number of observations we have made via SEM. Individuals of Brevianthusflavussubsp.flavus (Figs 3K; 4C, D) possess urceolate to clavate ‘papillae’ over the cell junctions on the abaxial leaf surface, at least between cells in the median-basal to basal portions of leaves, and at least sporadically on leaves along a single shoot. These ‘papillae’ have not been observed in individuals of Brevianthusflavussubsp.crenulatus (Figs 5E; 6C, D) or the type of Brevianthushypocanthidium (Figs 1E; 2C, D). Parts of these structures are removable with chloroform, providing evidence that they partly consist of surface waxes (Heinrichs and Reiner-Drehwald (2012)).


A new species of Brevianthus (Brevianthaceae, Marchantiophyta) from New Caledonia with unusual underleaf production.

Renner MA, Engel JJ, Patzak SD, Heinrichs J - PhytoKeys (2015)

Brevianthusflavussubsp.crenulatus: A leaf apex B cells below apex on abaxial leaf surface C, D abaxial leaf surface at mid-leaf E, F adaxial leaf surface. All from NSW745726. Scale: 20 µm (A, B, E, F); 10 µm (C, D).
© Copyright Policy - creative-commons-attribution
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4489084&req=5

Figure 6: Brevianthusflavussubsp.crenulatus: A leaf apex B cells below apex on abaxial leaf surface C, D abaxial leaf surface at mid-leaf E, F adaxial leaf surface. All from NSW745726. Scale: 20 µm (A, B, E, F); 10 µm (C, D).
Mentions: Leaf surface ornamentation may exhibit species-specific differences though there is intra-individual variation; our interpretation, however, may suffer from the relatively small number of observations we have made via SEM. Individuals of Brevianthusflavussubsp.flavus (Figs 3K; 4C, D) possess urceolate to clavate ‘papillae’ over the cell junctions on the abaxial leaf surface, at least between cells in the median-basal to basal portions of leaves, and at least sporadically on leaves along a single shoot. These ‘papillae’ have not been observed in individuals of Brevianthusflavussubsp.crenulatus (Figs 5E; 6C, D) or the type of Brevianthushypocanthidium (Figs 1E; 2C, D). Parts of these structures are removable with chloroform, providing evidence that they partly consist of surface waxes (Heinrichs and Reiner-Drehwald (2012)).

Bottom Line: A second species, Brevianthushypocanthidium, is described as new and is the first record of the genus for New Caledonia.Among its distinguishing characters are its shallowly bilobed leaves, and triangular underleaves present on small to medium-sized shoot sectors, the lack of a hyaline leaf margin, and the crenulate leaf margin formed by heavily thickened external cell walls.To explain these features we propose a competitive model of shoot formation wherein the ventral merophyte progressively loses vigor as its relative stature decreases, and its derivative cells become discontinuous and isolated along the ventral stem surface, with intervening areas occupied by derivatives of the more vigorous lateral merophytes.

View Article: PubMed Central - PubMed

Affiliation: Royal Botanic Gardens & Domain Trust, Mrs Macquaries Road, Sydney, NSW 2000, Australia.

ABSTRACT
Brevianthus is a distinctive genus of leafy liverwort in its succubously inserted, entire leaves, lack of underleaves, restriction of sexual organs to lateral-intercalary branches, scattered rhizoids and dense leaf-surface ornamentation. The sole species, Brevianthusflavus, is divided into two subspecies, one in Tasmania the other in New Zealand. A second species, Brevianthushypocanthidium, is described as new and is the first record of the genus for New Caledonia. Among its distinguishing characters are its shallowly bilobed leaves, and triangular underleaves present on small to medium-sized shoot sectors, the lack of a hyaline leaf margin, and the crenulate leaf margin formed by heavily thickened external cell walls. The most unusual features of the new species are the presence of underleaves between lateral leaf insertion lines that reach the ventral stem mid-line, and the absence of underleaves from larger shoots. To explain these features we propose a competitive model of shoot formation wherein the ventral merophyte progressively loses vigor as its relative stature decreases, and its derivative cells become discontinuous and isolated along the ventral stem surface, with intervening areas occupied by derivatives of the more vigorous lateral merophytes.

No MeSH data available.


Related in: MedlinePlus