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Studies on the lichens of the Azores.
Part 4. The genus Heterodermia
Roland Moberg & William Purvis
Moberg, R. & Purvis, W. 1996. Studies on the lichens of the Azores. Part 4. The genus
Heterodermia (Physciaceae). – Acta Univ. Ups. Symb. Bot. Ups. 32:1, 187–194. ISBN 91-
554-4108-4.
The genus Heterodermia is a conspicuous component of lichen vegetation in relict forests and
coastal rocks and vegetation in the Azores adding to the pantropical and subtropical biogeo-
graphical elements of the flora. Seven species are recognised: H. albicans (Pers.) Swinsc. &
Krog, H. japonica (Sato) Swinsc. & Krog, H. leucomela (L). Poelt, H. lutescens (Kurokawa)
Follman, H. obscurata (Nyl.) Trevisan, H. spathulifera Moberg & Purvis nov. sp. and H.
speciosa (Wulf.) Trevisan. H. propagulifera (Vain.) Dey is added to the synonymy of H.
japonica. Descriptive, chemical, ecological and distributional data for each species are pro-
vided.
Key words: Heterodermia, lichens, systematics, Azores, relict forest.
Roland Moberg, Botanical Museum, Uppsala University, Villav. 6, S-752 36 Uppsala, Sweden.
William Purvis, Department of Botany, The Natural History Museum, Cromwell Road, London
SW7 5BD, England
Introduction
This paper is the fourth in a series on the taxon-
omy, ecology and biogeography of the lichens of
the Azores (see Purvis & James 1993, Purvis et al.
1994 & Purvis et al. 1996). The Azorean archipel-
ago is situated in the Atlantic Ocean mid-way be-
tween Portugal and Newfoundland. The deeply
dissected volcanic terrain rising to 2350 m on the
island of Pico and to c. 900 m on most other is-
lands, provides an extensive range of habitats. The
climate is oceanic, with comparatively small sea-
sonal fluctuations in temperature and rainfall at sea
level although rainfall increases sharply with a rise
in altitude (Sjögren 1978). Cloud descends
almost daily to 700 m or lower throughout the
year on many islands; frosts are rare below 600 m.
The Azores are a major stronghold of important
remnants of the Tertiary evergreen forest, lauri-
silva formerly widely distributed in southern Eu-
rope (Tutin 1953; Haggar 1984, 1988). Eight of the
eleven native trees are endemic to the Azores.
Nowadays these native forests are under severe
threat from large-scale clearance for pasture, plan-
tations of exotic species and use for fire-wood.
They contain substantial populations (c. 30%) of
rare, vulnerable, or endangered macrolichens in-
cluded in the Red List of the European Community
(Sérusiaux 1989; Purvis et al. 1996), species rare
or extinct elsewhere in Europe. But as pointed out
by Purvis et al. (1996) this figure will be higher as
certain critical macrolichen genera, particularly
Cladonia, Heterodermia and Usnea are badly in
need of revision where it is probable that further
taxa remain to be described.
Endemism is a charactersitic feature of the
phanerogams in the Azores. Thus far seven Azo-
rean endemic cloud forest lichens have been de-
scribed: Nephroma hensenniae P. James & F.J.
White (James & White 1987), Ochrolechia azor-
ica Purvis, P. James & Brodo (Purvis et al. 1994),
188
Peltigera dissecta Purvis, P. James & Vitik., P.
melanorhizza Purvis, P. James & Vitik.), Ramonia
azorica P. James & Purvis (Purvis & James 1993),
Thelotrema antoninii Purvis & P. James and T. per-
foratum var. pauciseptatum (Purvis et al. 1995).
Preliminary biogeographical observations indi-
cate a strong presence of subtropical and pantropi-
cal elements including Parmelia (Aptroot 1989,
Arvidsson 1990), Physcia (Moberg 1989), Pyxine
and Coccocarpia (Aptroot 1989, Arvidsson 1990)
and Thelotrema (Purvis et al. 1995).
The genus Heterodermia is one of the commonest
foliose lichen genera in tropical and subtropical
regions with a few species reaching temperate re-
gions.
Originally monographed and included within
the genus Anaptychia by Kurokawa (1962),
though a comprehensive study for that time, a
modern world-wide revision is now badly needed
to take into account subsequent advances in chem-
ical analytical techniques and in interpretation of
ascomatal features. Poelt (1965) later separated
those species having thick-walled spores and con-
taining the substance atranorin (Heterodermia)
from those with thin-walled spores and lacking at-
ranorin (Anaptychia). A few regional studies were
also compiled, including for Pennsylvania (Cul-
berson 1966), India (Awasthi 1973) and East Af-
rica (Swinscow & Krog 1976), though there are
only limited studies at its centre of distribution in
tropical regions (Aptroot 1987).
Degelius (1941) included three species of Het-
erodermia (as Anaptychia) in his catalogue of 157
lichens for the Azores, mainly collected by the
bryologist H. Persson: A. leucomelaena Vain. (H.
leucomela), A. sorediifera (Müll. Arg.) Du Rietz &
Lynge (Heterodermia obscurata) and A. speciosa
(Wulf.) Trevisan (H. speciosa). Aptroot (1989)
later recorded Heterodermia japonica and H.
lutescens. Material of H. galactophylla Tavares
(1952) and H. isidiophora (Vain.) Awasthi (Mies
& Lösch 1995) were not available for study and
are excluded as doubtful records.
Material and Methods
The present study is based on the results of four
recent field visits made to the Azores by O.W. Pur-
vis, P.W. James and C.W. Smith during Spring
1992, 1993, 1994 and 1995, as well as by exami-
nation of herbarium material in BM, GB, UPS and
LIS. Observations and measurements of lichens
were made following procedures outlined in Pur-
vis et al. (1992). Some 200 specimens were exam-
ined and a complete list of specimens is held at
UPS and BM. Selected specimens are deposited at
the Department of Agricultural Sciences, Univer-
sity of Azores, Terceira (TER). Chemical analyses
were preformed using TLC and HPTLC (White &
James 1985, Arup et al. 1993). Spore measure-
ments were made in water mounts and have not
been statistically calculated because of limited
measurements available.
Key to species
1. Lobes dichotomously branched, ± linear ......................................................................................... 2
– Lobes sympodially branched, usually widening at tips.....................................................................3
2. Underside and soralia with yellow pigment (K–); soralia on recurved lobe ends............H. lutescens
– Underside without yellow pigment; soralia on lower surface and widening lobes........H. leucomela
3. With lobules................................................................................................................H. spathulifera
– Without lobules................................................................................................................................. 4
4. Without lower cortex ........................................................................................................................ 5
– Lower cortex present.........................................................................................................................7
5 Thallus of shiny, narrow (to 1mm) lobes with often whitish marginal rhizinae, lower
surface white ............................................................................................................... H. spathulifera
– Thallus of mat, wider (to 2 mm) lobes often with black, marginal rhizinae, lower
surface coloured................................................................................................................................ 6
189
6 Underside with blackish violet or yellowish (K–) tinged patches of pigment..................H. japonica
– Underside with yellow or rusty brown pigment (K+ purple) usually prominent............H. obscurata
7 Thallus with often whitish marginal rhizinae; with ‘spathulin’ ..................................H. spathulifera
– Thallus with blackish marginal rhizinae; without ‘spathulin’........................................................... 8
8 Medulla K+ yellow (atranorin); soralia apical, prominent, rarely coalescing
along margins ...................................................................................................................H. speciosa
– Medulla K+ blood red (salazinic acid); soralia starting on knob-like projections,
often coalescing along the margin ....................................................................................H. albicans
The species
1. Heterodermia albicans (Pers.) Swinsc. &
Krog
Fig. 1.
Lichenologist 8: 113 (1976).
Thallus orbicular to irregular, small, less than 3
cm diam., firmly adnate, densely lobate, grey to
brownish grey, darker at lobe tips, sometimes
weakly pruinose. Lobes narrow, 0.5(–1) mm, short,
to 3 mm, usually richly branched, weakly convex,
widening and tips without soralia, not ascending.
Soralia white to bluish grey, arising from small
lateral knob-like structures forming small, ± conti-
nous marginal soralia towards the thallus centre.
Lower surface corticate, whitish to pale brownish,
rarely dark grey, weakly rhizinate with usually
short (c. 1 mm) pale to dark brown or black rhiz-
inae. Upper and lower cortex prosoplectenchyma-
tous, together occupying more than 2/3 of the thal-
lus thickness. Apothecia and pycnidia not seen.
CHEMISTRY: K+ yellow to red, PD+ orange; atra-
norin, zeorin, salazinic acid and ± unidentified ter-
penes.
DISTRIBUTION AND HABITAT: Restricted to sunny
coastal rocks in Myrica faya scrub. Elsewhere
known from E. Africa and S. America.
NOTES: Characterised and easily distinguished by
the narrow, convex, short lobes, corticate on the
lower surface. The soralia arise from marginal
knob-like structures forming small, ± continous
marginal soralia towards the thallus centre. H.
speciosa also has a lower cortex but has larger, ±
flat lobes and lacks salazininc acid.
SPECIMENS EXAMINED. Sao Miguel. N. coastal area,
0,5 km E of Calhetas, 1977 James (BM); Faial da
Terra, 1977 James (BM, UPS); Ponta Delgada,
University Park, 1986 Degelius Az6 (UPS). Faial
Angustias, Monte da Guia, 100 m, 1976 James (BM)
2. Heterodermia japonica (Sato) Swinsc. &
Krog
Lichenologist 8: 122 (1976).
Heterodermia dendritica var. propagulifera (Vain.) Po-
elt Nova Hedwigia 9: 31 (1965). – Anaptychia dendrit-
ica var. propagulifera Vain. (Heterodermia propagulif-
era (Vain.) J.P. Dey) – Phil. J. Sci. 8: 107 (1913).
Thallus very variable, irregular, rarely orbicular,
to 5 cm, loosely adnate, lobe tips ascending, usu-
ally widening towards apices, whitish to cream-
coloured, rarely brownish, sometimes pruinose at
tips especially when young. Lobes ± fan-like, radi-
ating, broad, c .2 mm, to 3(–4) mm at the tips,
usually discrete, sometimes dissected with lobules
along the margin developing small soralia. Soralia
labiate, on lateral or terminal lobes, sometimes
spreading along lobe margin, soredia farinose to
granular. Lower side ecorticate, white to brownish
or bluish black, often sparsely dotted with brown-
ish orange-red pigment towards lobe apices, mar-
ginal rhizines mostly present, 1-3(-7) mm long,
simple and black. Known fertile from a single
specimen. Ascospores 40–45x20–22 µm. Pyc-
nidia rare, pycnoconidia bacilliform 4–5x1 µm.
CHEMISTRY: Thallus K+ yellow-red, Pd+ orange,
atranorin, zeorin, norstictic acid, ± salazinic acid
and unidentified terpenes.
DISTRIBUTION AND HABITAT. The most abundant and
widespread Heterodermia species in the Azores
190
Figure 1. Heterodermia albi-
cans. the Azores, São
Miguel, Faial de Terra, 1977
James (UPS). Bar 2 mm.
occurring on bark, rocks from sea level to 1000
m alt. and known from all major islands in the
Azores. Pantropical to subtropical extending to
warm temperate regions of Europe.
NOTES. Characterised by the dull upper surface, ±
fan-like lobe apices, the absence of a lower cortex
with a white to blackish violet lower surface. This
is however an exceedingly variable species in both
morphology and chemistry. The lobes may be-
come more elongate in shady habitats when they
may have distinct long, black marginal rhizines (to
7 mm). The soralia may vary from farinose to
granular or may be virtually lacking. The material
present in Azores corresponds to two chemical
strains with or without salazininc acid. Although
the salazininc acid strain is more frequent at higher
altitudes (> 500 m) there is no significant differ-
ences in morphology thus we have not adopted
these as separate taxa.
Swinscow & Krog (1976) indicate such a varia-
tion in E. Africa. The sparse brownish orange-red
pigment present on the lower lobe apices should
not be confused with the more distinct, continuous
pigmented lower surface of H. obscurata.
H. dendritica var. propagulifera was already
discussed and regarded as a modification of H.
japonica by Swinscow & Krog (l.c. 133) and they
have examined the holotype in TUR and the iso-
type in BM. We fully agree with their conclusions
and thus formalize the synonymization.
SPECIMENS EXAMINED. material has been seen from
Faial, Pico, Santa Maria, Sao Miguel, Sao Jorge and
Terceira.
3. Heterodermia leucomela (L.) Poelt
Nova Hedwigia 9: 31 (1965).
Thallus appearing fruticose, of irregular, narrow,
sometimes several cm long, interwoven lobes car-
rying long cilia (rhizinae) along the margin, whit-
ish to cream-coloured, shiny without pruina.
Lobes 1(–1.5) mm wide, parallel-sided, not widen-
ing towards apices, dichotomously branched with
long, sparesly squarrose rhizinae, black except for
the pale base. Soralia irregularly formed on the
underside causing the lobes to widen. Lower side
ecorticate, white or rarely purple, margin corticate
and prominent. Upper cortex around half of the
lobe thickness. Apothecia rather rare, 2(–3) mm
diam., stipitate, disc black, ± pruinose, margin
crenulate to lobulate. Spores 35-50x15-22 µm
(only a few seen). Pycnidia rare; pycnoconidia 4–
5x1 µm.
191
CHEMISTRY. K+ yellow to red, P+ yellow, atran-
orin, zeorin and ± salazinic acid
DISTRIBUTION AND HABITAT: Abundant throughout
the Azores from sunny coastal rocks and walls to
mossy trees in the moist cloud forest to 1000 m alt.
One of the most widespread and abundant species
throughout tropical and subtropical regions ex-
tending to warm temperate areas. Two subspecies
were recognized by for instance Swinscow & Krog
(1976), according to morphological and chemical
variation, though in the Azores it is not possible to
separate our material to the rank of subspecies.
NOTES. Easily characterised by the entangled
mats of elongate, linear lobes bearing long black
cilia and the ecorticate lower surface with thick
corticate margins.
SPECIMENS EXAMINED: material has been seen from
Faial, Flores, Pico, Sao Miguel and Terceira.
4. Heterodermia lutescens (Kurok.) Follman
Phillipia 2: 73 (1974).
Thallus appearing fruticose, irregular, small, with
± erect, ciliate lobes, brownish white to cream-
coloured, rarely darker brown, ± shiny and without
pruina. Lobes narrow, c. 0.5(–1) mm, short, c. 5(–
10)mm, ± dicotomously branched, cilia to 5 mm.
Soralia terminal, on the underside; soredia
granular, pale yellow. Lower side ecorticate with
thick, corticate and prominent margin, white with
a yellow, K– pigment; cilia black, rarely squarrose.
Apothecia and pycnidia not seen.
CHEMISTRY: K+ yellow, atranorin, zeorin.
DISTRIBUTION and habitat: Widely distributed
throughout Azores, occurring on mossy rocks near
the coast as well as on mossy trees within the
cloud forest to an altitude of c. 500 m. H. lutescens
is mainly tropical and otherwise known from C.
and S. America, Japan, Papua New Guinea and
Africa.
NOTES: Easily distinguishable in the field by the
neat mats of small, erect yellow-tinged lobes bear-
ing conspicuous pale yellow soralia and yellow
underside. Bears a superficial resemblance to
small individuals of H. leucomela which differ in
their grey-white colour.
SPECIMENS EXAMINED: Pico. Eastern end of island, Pie-
dade above Cabeco da Hera, 100 m, 1978 James (BM,
UPS); Madalena, Arete Larga, 1978 James (BM);
Cabeco Pequeno, 4 km E of Madalena, 1978 James
(BM); W of Calheta de Nesquim, Manhenha, near
lighthouse, 1978 James (BM, UPS); c. 1 km W of
Cabeco do Ferrobo, c. 7 km NW of Lajes, 500 m, 1981
Löfgren 1283 (UPS). Santa Maria. Pico Alto, 550 m,
1977 James (BM, UPS, to be distributed in Moberg,
Lich. sel. exs. Ups.). Terceira. Above Doze Ribeiras,
350 m, 1978 James (BM)
5. Heterodermia obscurata (Nyl.) Trevisan
Nuovo Giorn. Bot. Ital. 1: 114 (1869).
Thallus forming ± orbicular rosettes or irregularly
spreading, robust, 2–3(–4) cm diam., ± firmly ad-
nate, grey-white to rarely dark grey, shiny, not or
rarely pruinose. Lobes c. 1(–2) mm, radiating,
sparesly divided, ± discrete, flat to slightly convex.
Soralia labiate on lateral and terminal lobes,
sometimes confluent forming marginal soralia, of-
ten rusty brown coloured by the medullary
pigment, soredia granular. Lower side ecorticate,
felted with rust-coloured or yellowish brown pig-
ment, K+ purple, not to be mixed with the bluish
black underside present in H. japonica, with black
marginal rhizinae. Apothecia and pycnidia not
seen.
CHEMISTRY. K+ yellow, atranorin, zeorin, un-
identified terpene.
DISTRIBUTION AND HABITAT. On mossy rocks by
the coast extending to c. 700 m alt. within laurel
forest where it occurs amongst mosses on all
epiphytes. Common and widespread in tropical
and subtropical areas, extending to warm
temperate regione in Europe (Purvis et al. 1992).
NOTES. Characterised by its robust appearance, the
distinct labiate soredia and the rusty brown pig-
mented (K+ purple) lower surface. Similar species
include H. japonica which differs in having a K+
192
Figure 2. Heterodermia
spathulifera Holotype.
Bar 2 mm.
yellow-red medullary reaction and not pigmented
or with only sparse rusty brown pigment (K–) on
its lower surface. Another similar species, H. spe-
ciosa, is distinguished by having a lower cortex
and lacks any rusty brown pigmentation.
SPECIMENS EXAMINED: Faial. Ribeirinha, Porto da
Booa da Ribeira, also via Rontinha, 100 m, 1976
James (BM); Above Ribeira do Cabo, lower slopes of
Cabeco Verde and Cabeco do Fogo, 300 m, 1976
(BM). Pico. Eastern end of island, Piedade above
Cabeco da Hera, 100 m, 1978 James (BM, UPS); NW
slopes of Pico, c. 3 km S of road EN-3 through
Cerrado de Sonicas, S of track leading to aerial, 1000
m, 1992, Purvis & James (BM); c 1 km W of Cabeco
do Ferrobo, c. 7 km NW of Lajes, 500 m, 1981
Löfgren 1285, 1292 (UPS). Santa Maria. Pico Alto,
550 m, James (BM); Road to summit of Pico Alto, 500
m, 1977 James (BM). Sao Miguel. Furnas, 1937
Persson (UPS); Caldeira das Sete Cidades, c. 15 km
NW of Ponta Delgada, 365 m, 1981 Löfgren 1227
(UPS). Terceira. 6 km S of Quatro Ribeiras, Algar do
Carvao, 550 m, 1978 James (BM); Above Doze
Ribeiras, along EN5-2, 350 m, 1978 James (BM); 5
km NNW of Biscoitos, Roche do Juncal, 600 m, 1995
Purvis, James & Dias 5076 (BM); 6.75 Km S of
Altares, Misterio Negro, 640 m, 1994, Purvis & James
(BM); E side of Ponta da Misterio, east of Quatro
Ribeiras, 150 m, 1995, Purvis, James & Smith 5077
(BM, TER)
6. Heterodermia spathulifera Moberg & Purvis
nov. sp.
Thallus foliaceus, orbicularis, adpressus, diametro usque
ad 3 cm, superne griseus, subtus ecorticatus, griseus.
Rhizinae pallidae, paucae. Lobi radiati, usque ad 1 mm
lati. Soralia terminalia, labiata vel spathulata. Apothecia
rara, sporae 36-43x15-18 µm. Pycnidia non visa. A
Heterodermia albicanti soraliorum forma et substantiis
chemicis aliis differt.
Holotype: The Azores, St. Michel, Furnas, on a tree in
the park. 3.IV.1937 H. Persson no H2 (UPS).
Fig. 2.
Thallus irregular to orbicular, to 3 cm diam. with
discrete to adjacent, firmly adnate lobes bearing
marginal rhizinae visible from above, white to
cream-coloured, shiny and without pruina. Lobes
narrow, to 1 mm, usually flat, not distinctly widen-
ing at tips, rhizinae sparse, c. 1(–2) mm, simple,
white or cream, sometimes appearing as cilia on
the margin. Soralia labiate, sometimes becoming
very big (to 5mm tall) and spathulate. In moist and
shaded habitats the soredia tend to develop into
squamules which sometimes may cover inner parts
of the thallus. Underside ecorticate, white on outer
parts of lobes, pale brown in inner parts (appearing
corticate, but in sections this proves to be medulla
incrusted by soil particles). Upper cortex thick,
prosoplectenchymatous. Apothecia rare, only one
seen with either immature or overmature spores,
36-43x15-18 µm. Pycnidia not seen.
CHEMISTRY: K+ yellow, C–, KC– P– ; atranorin,
zeorin, unidentified substance, UV+ red after
charring rf 4–5 (G) [‘spathulin’].
193
DISTRIBUTION AND HABITAT. On coastal rocks, on
Picconia azorica, and Pittosporum undulatum, on
the islands of Pico, Faial, Teiceira, Flores, Santa
Maria and Sao Miguel. So far known only from
the Azores.
NOTES. Distinguished by its narrow, shiny, firmly
adnate lobes with pale marginal rhizinae and
unique chemistry containing an unknown sub-
stance, ‘spathulin’ appearing reddish in UV above
zeorin after treatment with sulphuric acid. If sor-
alia present they are usually big and spathulate.
The only other Heterodermia typical of coastal sit-
uations in the Azores with small adnate lobes is H.
albicans which differs in having, darker lobes with
small marginal knob-like projections developing
into soralia and a very disitnct lower cortex.
SPECIMENS EXAMINED: Faial. Above Ribeira do Cabo,
lower slopes of Cabeco Verde and Cabeso do Fogo,
275-550 m, 1976 (BM, UPS); Ribeirinha, Porto da Booa
da Ribeira, 100 m, 1976 James (BM). Varadouru, 1976
James (BM); Praia da Norte, Porta da Faja, 45 m, 1976
James (BM). Flores. 2 km W of Ponta Delgada, S of
bridge over Ribeiro da Moinho, 85 m, 1995, Purvis,
James & Smith 5010 (BM, TER, HAW). Pico. W of
Calheta de Nesquim, Manhenha, near lighthouse, 1978
James (BM); Encruzilhada, 7 km ESE of Candelaria, c.
1 km SW of Selado, 480 m, 1992, Purvis & James 5002
(BM); 2.5 km S of Piedade, Cabeço da Hera, along and
south of small road leading to Manhenha, 130 m, 1993
Purvis, James & Smith 5001 (BM); 4 km S of Piedade,
Cabeço da Hera, Sra das Merces, alongside track above
Baia de Domingos Pereira, 80 m, 1993 Purvis, James &
Smith 5005 (HAW); 3.5 km NE S. Joao, Cabecinhos,
off west side of road at junction of EN-2 with junction to
S. João, 520 m, 1993 Purvis & James 5003 (BM); 8.5
km SSE of S. Roque do Pico, Misterio da Prainha, 480
m,1992 Purvis & James 5007 (TER); 4 km S of Piedade,
Cabeço da Hera, Sra das Merces, alongside track above
Baia de Domingos Pereira, 80 m, 1992 Purvis & James
5008 (BM). Santa Maria. Summit of Pico alto, 500 m,
1977 James (BM). Sao Miguel. Furnas, the park, 1937
Persson (UPS); Capellas, at the sea, 1937 Persson H8
(UPS); 1986 Degelius Az257 (UPS); E of Sao Miguel,
Furnas Gardens, Furnas, 1996 Purvis, James & Smith
(BM); Terceira: c. 1 km S of Angra do Heroismo, 175
m, 1994 Purvis & James 5004 (TER); 5006 (BM).
7. Heterodermia speciosa (Wulf.) Trevisan
Atti Soc. Ital. Sci. Nat. 11: 614 (1869).
Fig. see Moberg & Holmåsen 1990.
Thallus orbicular to irregular, 2–3(–4) cm diam.,
often coalescing with other thalli, ± firmly adnate,
white to cream-coloured or brownish grey, appear-
ing bluish by the dense soralia, ± shiny, the lobe
tips sometimes darkening, very rarely pruinose,
not ascending. Lobes narrow, c. 1(–2) mm, flat to
convex, end-lobes without soralia, slightly widen-
ing towards apices. Soralia abundant labiate on
lateral lobes, sometimes semicapitate, starting
from lateral lobules, soredia farinose to ± granular,
grey to bluish grey. Lower side pale to dark brown
with few scattered, short and robust, usually black
rhizinae. Lower cortex present, prosoplectenchy-
matous. Apothecia and pycnidia not seen.
CHEMISTRY: K+ yellow; atranorin, zeorin, un-
identified triterpene.
DISTRIBUTION AND HABITAT: On sunny, coastal
rocks. Widely distributed in subtropical to temper-
ate areas, extending to northern Scandinavia
(Moberg & Holmåsen 1990).
NOTES: Characterised by the striking contrast
between the blue-grey soralia and the paler thallus,
the presence of lower cortex. The lower surface of
H. obscurata lacks a cortex and has a rusty orange
pigment. H. albicans is much smaller and contains
salazininc acid (K+ yellow-red).
SPECIMENS EXAMINED: Faial. Horta, Angustias, Guia,
Monte da Guia, 100 m, 1976 James (BM); Castelo
Branco, Pedreiras mainland opposite Ponta de Castelo
Branco, 1976 James (BM, UPS). Pico. Lajes do Pico,
Barra, Castelete, 1978 James (BM). Sao Jorge. Villa
des Vehlas, 1937 Persson (UPS). Terceira. Angra, 1937
Persson (UPS); E side of Ponta da Misterio, east of Qua-
tro Ribeiras, 150 m, 1995 Purvis, James & Smith 5078
(BM).
Acknowledgements
OWP gratefully acknowledge receipt of a grant from
Professor C. W. Smith (University of Hawaii) and Dr.
H. R. Martins and Dr. E. Dias (Universidade dos
Acores) are thanked for their most generous logistical
support. The latin diagnosis has kindly been revised by
Professor Lennart Holm, Uppsala. We thank the
curators of the herbaria cited for the loan of material.
194
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