The Lichenologist 42(6): 697–700 (2010)
doi:10.1017/S0024282910000484
© British Lichen Society, 2010
Parmeliella borbonica, a new lichen species from Réunion
Per M. JØRGENSEN and Felix SCHUMM
Abstract: The new species Parmeliella borbonica is described. It belongs in a small group of species,
which, unlike all other Parmeliella species except those of the Parmeliella mariana group, have thalline
squamulose margins of the apothecia, and are thus superficially reminiscent of Pannaria. The group is
mainly Indo-pacific. A key to the species is given. Parmeliella borbonica appears to be an addition to the
many remarkable endemic members of the Pannariaceae found in Réunion which has retained old
Gondwana elements, as its lowland forests have not been destroyed as much as those in the
neighbouring region. The very rare Coccocarpia imbricascens Nyl. was found as new to the island, and
the rare endemic Pannaria multifida P. M. Jørg close to its type locality.
Key words: endemism, Indo-pacific relations, taxonomy
Introduction
Despite its rather young age, Réunion is a
lichenologically most interesting island,
home to a number of endemic species, particularly in the Pannariaceae (Jørgensen et al.
2009). The second author visited the island
in 2009 and collected several interesting
specimens of the Pannariaceae, which have
been revised by the first author. Among them
was a very unusual looking collection, at
first sight reminiscent of the West-Indian
Pannaria caesiocinerea (Vain.) P. M. Jørg.,
but on closer inspection proving to contain
no secondary lichen substances and to have
an amyloid, internal apical ring-structure
(Fig. 1C), both characters clearly placing it in
Parmeliella, in spite of the squamulose thalline margin of the apothecia. It certainly
belongs in that little group of species where
the newly described Parmeliella zeylanica
P. M. Jørg. is placed (Jørgensen 2009), which
may prove to need acceptance on some level,
but at the moment is best kept within
the genus Parmeliella. The specimen from
Réunion is clearly different from any other in
P. M. Jørgensen: Department of Natural History,
Bergen Museum, University of Bergen, Allégt.-41,
N-5007 Bergen, Norway.
F. Schumm: Mozart str. 9, BRD-73117 Wangen,
Germany.
this mainly Indo-pacific group (see below),
and is accordingly described as new.
Material and Methods
The material is that cited below and the methods are the
same as in previous papers by the first author.
The New Species
Parmeliella borbonica P. M. Jørg. & F.
Schumm sp. nov.
Parmeliellae zeylanicae similis, sed thallo tenue, applanato et caesiocinereo, medulla incolorata et sporis magnis, 10–15 × 8–10 m.
Typus: La Réunion, Takamaka, low mountain forest
near the electrostation, alt. 790 m, 10 September 2009,
J.-P. Frahm & F. Schumm (BG—holotypus!; hb.
Schumm 15265—isotypus).
(Fig. 1)
Thallus bluish grey with whitish margins,
squamulose, forming appressed, orbicular
patches, up to 3 cm diam. of imbricating
lobes, centrally nearly crustose, marginally
up to 3 mm broad, 60–100 m thick with a
paraplectenchymatous upper cortex. The
blackish prothallus is poorly developed,
mostly crustaceous and not extending
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THE LICHENOLOGIST
Vol. 42
F. 1. Parmeliella borbonica. A, habitus; B, anatomy of the apothecium; C, an ascus in Lugol’s iodine. Scales:
A = 5 mm; B = 100 m; C = 10 m.
beyond the marginal lobes. Upper cortex distinct, cellular 15–25 m wide, upon a loose
medullary layer, enclosing packets of Nostoc,
individual cells of which measure 3–5 m
diam. Lower cortex absent.
Apothecia laminal, sessile, up to 1·5 mm
diam., often aggregated in groups, disc
light brown, flat; margins wavy to slightly
lobed with thalline squamules attached.
Hymenium 100–125 m high, I+ blue, made
2010
Parmeliella borbonica—Jørgensen & Schumm
up of simple, septate hyphae, apically thickened with external brown pigment. Asci narrowly subcylindrical, 70–80 × 6–10 m,
apically with internal amyloid ring-structure
(Fig. 1), 8-spored. Ascospores subglobose,
simple, colourless, 10–15 × 8–10 m with
fairly smooth exospore without extensions.
Conidiomata not observed.
Chemistry. All reactions negative. No
lichen substances or pigments detected by
TLC.
Additional specimen examined. La Réunion: NE of
Plaine-des-Palmistes, trail E of lake ‘Grand Étang’, from
parking lot to the lake in sloping W-exposed, tropical
rainforest on guave, alt. 570 m, 2008, P. & B. van den
Boom, A. M. Brand, E. Sérusiaux 40037 (hb. P. v.d.
Boom).
Ecology and distribution. As yet known only
from two localities, and possibly an endemic.
The type grows on an old tree in a wet,
lowland forest at 790 m altitude near the
beginning of the trail that leads down from
the station Belvédere (EDF electro power
station) to the reservoir Takamaka. This
steep, north side of the Rivière des Maison
canyon, where also Grand Étang (the other
collection) is situated, is one of the two wettest regions in the east of Réunion (annual
rainfall 7 m). In the vicinity numerous
species of the Coccocarpiaceae, Collemataceae
(e.g., Leptogium denticulatum auct.), Pannariaceae and Stictaceae (e.g., Pseudocyphellaria
desfontainii (Delise) D. J. Galloway) occur,
with the commonest foliose lichen in that
locality being Sticta caperata (Nyl.) Bory,
a palaeotropical species described from
Réunion. Remarkable occurrences here are
the very rare Coccocarpia imbricascens Nyl.,
which until recently was known only from its
unlocalized type (Arvidsson 1983), but has
since been discovered in South America
(Lücking et al. 2007), as well as the palaeotropical Coccocarpia smaragdina Pers., and
the endemic Pannaria multifida P. M. Jørg.
(Jørgensen 2004). The concentration of
rare and endemic species, mostly with
palaeotropical affinity, in this locality is most
possibly due to the rarity of this kind of
lowland forest, which has been cleared away
699
in most of the neighbouring islands (e.g.,
Madagascar and Mauritius), but is still
present on the steep mountain-sides in
Réunion where obviously many of the once
presumably more widespread, palaeotropical
species are still to be found. This is confirmed by the occurrence in the second locality, which is also in a lowland, moist tropical
forest, close to the type locality of Pannaria
multifida.
Notes. In spite of the external Pannaria-like
appearance, the bluish grey thallus and
apothecia with thalline margins, this is a
Parmeliella as is obvious from the lack of
pannarin in the thallus, and above all by the
internal apical apparatus of the asci which
is amyloid and forms a ring-structure (Fig.
1C), most typical of the genus Parmeliella.
This genus typically (traditionally) has no
thalline margin of the apothecia, although
this character is now known to be of little
taxonomic value. There are quite a few similar species, mainly tropical, with these characteristics, the Parmeliella mariana group,
most of which form large, circular thalli with
spreading marginal lobes, resting on a conspicuous mat of rhizohyphae, usually called
a hypothallus. There are also a few more
squamulose taxa, mostly in the Indo-pacific
region, to which this species is most closely
related, though it probably reminds one
mostly of the South American Parmeliella
imbricatula (Müll. Arg.) P. M. Jørg. (a species
belonging in the P. mariana group), which
has a thicker thallus of more discrete squamules and more regular, strongly margined
apothecia (see Jørgensen 2003), with narrower, ellipsoid spores. It is definitely closer
to the two brownish species from Sri Lanka.
The equally small-squamulose Parmeliella
zeylanica P. M. Jørg. has a looser thallus with
yellowish medulla and smaller spores. In
many ways P. borbonica appears to be closest
to P. leiostroma (Nyl.) P. M. Jørg., owing to
the thin, adnate thallus, which in that species
is brownish and rests on a distinct mat of
brownish rhizohyphae. The spores of that
species are also ellipsoid and narrower than
in P. borbonica. These species appear to form
a neat group, the most widespread species of
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which is P. endomilta Vain., a brownish
species with a thin thallus and an orange
medulla and citriform spores, distributed
throughout the region of the Indian Ocean
eastwards to New Guinea (Jørgensen &
Vol. 42
Sipman 2006). A key to the members of this
highly characteristic group, which may prove
to be in need of a higher taxonomic rank, is
presented below.
Key to Parmeliella endomilta and allies
1
Thallus bluish grey, medulla always unpigmented . . . . . . . . . . . . . . . . . 2
Thallus brownish, medulla often pigmented . . . . . . . . . . . . . . . . . . . . 3
2(1)
Thallus cracked, on a distinct hypothallus; spores narrowly ellipsoid, 12–15 ×
5–6 m; South America . .Parmeliella imbricatula (Müll. Arg.) P. M. Jørg.
Thallus continuous, no hypothallus visible; spores subglobose, 10–15 × 8–10 m;
Réunion . . . . . . . . . Parmeliella borbonica P. M. Jørg. & F. Schumm
3(1)
Thallus with yellow or orange medulla, hypothallus indistinct . . . . . . . . . . . 4
Thallus with unpigmented medulla, hypothallus distinct; Sri Lanka. . . . . . . . .
. . . . . . . . . . . . . . . . . . . Parmeliella leiostroma (Nyl.) P. M. Jørg.
4(3)
Thallus skin-like, more or less continuous, medulla orange, spores citriform, hypothallus indistinct; widespread in Indo-Pacific region . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . Parmeliella endomilta Vain.
Thallus discretely squamulose, medulla pale yellow, hypothallus indistinct, spores
drop-like; Sri Lanka . . . . . . . . . . . . . Parmeliella zeylanica P. M. Jørg.
We are indebted to the curators of BM and G, and Pieter
van den Boom who sent us material on loan. F. Schumm
would like to express his thanks to André Aptroot for
continuous support and encouragement in his work on
tropical lichens.
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Accepted for publication 23 June 2010