Tuatara: Volume 4, Issue 2, December 1951
New Zealand Lichens — — A Key to the Family Umbilicariaceae
New Zealand Lichens
— A Key to the Family Umbilicariaceae
Members of the lichen family Umbilicariaceae or Gynophoraceae grow on rocks, especially where strongly insolated. They are usually easily recognized by their black or very dark, leathery, more or less orbicular thalli, attached to the rock by a more or less central holdfast (umbilicus). The thallus is mono- to poly-phyllous, often lobed. The upper cortex may be smooth, or in a few species bear soredia, isidia, or lobules. The lower cortex is often paler than the upper; it may bear scattered or grouped rhizines, often making a marginal fringe. These rhizines do not act as holdfasts, but absorb water. In some species plate-like lamellae are developed. Both surfaces may show a layer of dead cells, looking like encrusting crystals when dry, gelatinous when wet.
The apothecia are circular, up to about 5 mm. diam., sessile or shortly stalked. Three forms of disk may be found, but never on the same thallus:
leiodisc — smooth, flat, surrounded by ‘proper’ margin;
omphalodisc — more or less smooth and fiat, but bearing a central column of vegetative hyphae that in some species later disappears, leaving a cavity. The surface may present more or less gaping fissures;
gyrodisc — the surface is thrown into prominent folds (gyri) containing the asci, separated by slits.
The family is variously dealt with; split into a number of genera by some, lumped into a single genus by others. A collection of New Zealand specimens, mostly gathered by the late Mr. J. Scott Thomson, has recently been studied by Dr. G. A. Llano during the preparation of his monograph on the genera and species of the western hemisphere. Llano follows the scheme of Scholander, and his arrangement of the New Zealand species is followed here. We still know far too little of their distribution, especially in the North Island.
Of the 8 species so far recognized in New Zealand, Omphalodiscus subaprinus appears to be endemic. Agyrophora zahlbruckneri, described from North Island material, was found by Llano also to occur in Ecuador, Chile, and Argentina. Agyrophora leiocarpa, not quite definitely known from New Zealand, is a bipolar species. The remainder are cosmopolitan.
There is evidence that the acid of these lichens plays a part in the gradual disintegration of the rock surface. A. L. Smith (‘Lichens’, 1921, p.404) says: ‘They are the “Tripe de Roches” or Rock Tripe of Arctic regions, a name given to the plants by Canadian fur-hunters. They have page 60 been eaten by travellers and others in desperate straits for food, but though to a certain extent nutritious, they are bitter and nauseous, and cause severe internal irritation if the bitter acids are not first extracted by boiling or soaking.’ I have not tried boiling, but can testify to the bitterness of the raw plants.
A glossary of terms used in describing lichens is included with the previous keys to the lichens (Tuatara 1 (3): 20-35; 2 (1): 15-21; 2 (2): 97-101).
Key to Genera and Species in New Zealand
|1||Apothecia with conspicuous gyri (gyrodisc)||Umbilicaria|
|Apothecia without gyri||— 2|
|2||Apothecia with smooth disk, without central column of vegetative hyphae or central cavity (leiodisc)||Agyrophora|
|Apothecia with central column of vegetative hyphae or central cavity, usually with fissured disk (omphalodisc)||Omphalodiscus|
|Thallus mono- to poly-phyllous, dorsal surface never strongly wrinkled; with or without rhizines; apothecia usually present on smooth flat disk.|
|1||Rhizines marginal; thallus ca. 2-4 cm. diam.||A. zahlbruckneri|
|Rhizines absent; thallus ca. 5-15 cm. diam.||A. leiocarpa|
|Thallus mono- to subpoly-phyllous; young apothecia with prominent sterile central column; adult apothecia with persistent column, or this represented by a central often branched fissure.|
|1||Dorsal surface distinctly reticulately rugose||O. decussatus|
|Dorsal surface not or very weakly rugose||O. subaprinus|
|Thallus mono- to poly-phyllous; apothecia when mature with conspicuous gyri.|
|1||Upper surface covered with narrow vermiform ridges||U. hyperborea|
|Upper surface not so ridged; undulating to folded, may be areolate||— 2|
|2||Lower surface without rhizines or lamellae||U. polyphylla|
|Lower surface with rhizines||— 3|
|3||Lower surface without lamellae, not papillose||U. cylindrica|
|Lower surface with lamellae, papillose||U. vellea|
A. zahlbruckneri. Thallus ca. 2-4 cm. diam., mono- to poly-phyllous; margins incised, irregularly lobed; upper surface somewhat undulate, usually quite smooth; umbilicus small; rhizines usually short, ventral or page break
Legends to Figures
var. robusta. Thallus smaller, not over 2 cm. diam; lower surface densely clad in robust rhizines. Known so far only from type collection of W. Martin from Mount Anglem (Stewart Island) at 900 m.
A. leiocarpa. Plentiful in arctic and antarctic regions, with thallus up to 8 cm. diam., monophyllous with irregular fragile margins deeply incised. Reported from New Zealand as amongst specimens of U. hyperborea collected on Mount Torlesse, (Zahlbruckner, Lichenes Novae-Zelandiae, 1941, 81) but not found in the portion of the gathering retained in New Zealand.
O. decussatus. Thallus usually not much over 5 cm. diam., often less, usually monophyllous, coriaceous, orbicular, rugi usually well developed; apothecia seldom developed, up to 3 mm. diam. Known in New Zealand from Mounts Tapuaenuku, Ida and Pisgah.
O. subaprinus. The type specimens were collected on Mount Tapuaenuku at ca. 2100 m. Thallus ca. 1-2 cm. diam., monophyllous, margins not incised; lower surface and margins densely clad in rather stout rhizines; apothecia ca. 1-2 mm. diam. Further collections from Mount Pisgah and Mount St. Mary (Kurow) have been described as var. du-reitzii; upper cortex more uneven, rimulose-granulose; apothecia immersed, surrounded by radiating cracks; rhizines when present mainly peripheral.
U. hyperborea. Thallus 2-5 cm. diam. or more, monophyllous, often with epithalline lobed excrescences; upper surface undulate, covered with vermiform ridges; lower surface more or less bullate; apothecia 1-2 mm. diam. Has been collected on Mount Torlesse, Port Hills of Christchurch, Mounts Pisgah, Misery, and Ida of Otago.
U. polyphylla. Thallus 2-6 cm. diam., usually polyphyllous, thin, membranous, fragile, with irregular outline; apothecia rare, mostly peripheral. Apparently the commonest species in New Zealand; collected on a number of mountains from north to south of South Island.
U. cylindrica. Thallus 2-10 cm. diam., polyphyllous; upper surface pruinose, margins crenate to cleft; lower surface and margins sparsely to rather densely clad in rhizines. Apothecia 2-4 mm. diam., mostly marginal. A polymorphic species. Known in New Zealand from Mount Egmont, Mount Torlesse, and Mounts Pisgah, Ida and Watkins, but probably, as with U. polyphylla, of fairly continuous distribution. The var. tornata with rosetted, pulvinate thallus, has the same distribution.
U. vellea. Thallus 6-15 cm. or more diam., monophyllous, orbicular; upper surface undulate, sometimes folded; margins incised or not; umbilicus rather large; lower surface often lamellate, papillate; rhizines often short, clavate, sometimes elongate; apothecia not common, 1.5-3 mm. diam. Known in New Zealand on a number of mountains from north to south of South Island, descending to ca. 300 m. in south of range.