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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 lateral view of shoot B dorsal view of shoot C habitus D ventral view of shoot E abaxial leaf cell surface F cell margin at leaf apex, one leaf-lobe featured G leaf showing crenulate hyaline cells prominent on dorsal margin H–L leaves dissected and flattened M ventral view of shoot N leaf apex O dorsal view of regenerant showing bulging cells and bifid leaf apices P lateral view of regenerant attached to adaxial side of single cell near the leaf margin at shoot base Q lateral view of stem, apex to left. All from NSW745726. Scale: 500 µm (A, B, D, H–M); 3000 µm (C); 50 µm (E, F); 250 µm (G, O, P, Q); 200 µm (N).
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Figure 5: Brevianthusflavussubsp.crenulatus: A lateral view of shoot B dorsal view of shoot C habitus D ventral view of shoot E abaxial leaf cell surface F cell margin at leaf apex, one leaf-lobe featured G leaf showing crenulate hyaline cells prominent on dorsal margin H–L leaves dissected and flattened M ventral view of shoot N leaf apex O dorsal view of regenerant showing bulging cells and bifid leaf apices P lateral view of regenerant attached to adaxial side of single cell near the leaf margin at shoot base Q lateral view of stem, apex to left. All from NSW745726. Scale: 500 µm (A, B, D, H–M); 3000 µm (C); 50 µm (E, F); 250 µm (G, O, P, Q); 200 µm (N).

Mentions: Characters of the leaf apex and margins are useful in distinguishing the taxa of Brevianthus. The leaf apex of Brevianthushypocanthidium (Fig. 1O) is shallowly but distinctly bifid, and this is a consistent feature of leaves of all sizes, though on the smallest leaves of leaf-borne propagules this is obscure. In Brevianthusflavussubsp.crenulatus small leaves are bifid (Fig. 5O, P), while medium and large leaves have an undivided apex (Fig. 5G–L). In Brevianthusflavussubsp.flavus the leaf apex is always undivided and entire (Fig. 3E–J).


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 lateral view of shoot B dorsal view of shoot C habitus D ventral view of shoot E abaxial leaf cell surface F cell margin at leaf apex, one leaf-lobe featured G leaf showing crenulate hyaline cells prominent on dorsal margin H–L leaves dissected and flattened M ventral view of shoot N leaf apex O dorsal view of regenerant showing bulging cells and bifid leaf apices P lateral view of regenerant attached to adaxial side of single cell near the leaf margin at shoot base Q lateral view of stem, apex to left. All from NSW745726. Scale: 500 µm (A, B, D, H–M); 3000 µm (C); 50 µm (E, F); 250 µm (G, O, P, Q); 200 µm (N).
© Copyright Policy - creative-commons-attribution
Related In: Results  -  Collection

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

Figure 5: Brevianthusflavussubsp.crenulatus: A lateral view of shoot B dorsal view of shoot C habitus D ventral view of shoot E abaxial leaf cell surface F cell margin at leaf apex, one leaf-lobe featured G leaf showing crenulate hyaline cells prominent on dorsal margin H–L leaves dissected and flattened M ventral view of shoot N leaf apex O dorsal view of regenerant showing bulging cells and bifid leaf apices P lateral view of regenerant attached to adaxial side of single cell near the leaf margin at shoot base Q lateral view of stem, apex to left. All from NSW745726. Scale: 500 µm (A, B, D, H–M); 3000 µm (C); 50 µm (E, F); 250 µm (G, O, P, Q); 200 µm (N).
Mentions: Characters of the leaf apex and margins are useful in distinguishing the taxa of Brevianthus. The leaf apex of Brevianthushypocanthidium (Fig. 1O) is shallowly but distinctly bifid, and this is a consistent feature of leaves of all sizes, though on the smallest leaves of leaf-borne propagules this is obscure. In Brevianthusflavussubsp.crenulatus small leaves are bifid (Fig. 5O, P), while medium and large leaves have an undivided apex (Fig. 5G–L). In Brevianthusflavussubsp.flavus the leaf apex is always undivided and entire (Fig. 3E–J).

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