Introduction
Despite having a high diversity of species and high degree of endemism (Lagos & Muller Reference Lagos and Muller2007), the Atlantic rainforest in Brazil has been devastated and increasingly threatened, with over 93% of its area already destroyed (Galindo-Leal & Câmara Reference Galindo-Leal, Câmara, Galindo-Leal and Câmara2005). During a floristic survey of corticolous crustose lichens in Mata Atlântica fragments in north-eastern Brazil, two undescribed species of the genus Malmidea from Mato do Crasto and Serra da Jibóia were found and are described below.
Mata do Crasto is one of the most important Atlantic forest remnants in Sergipe, the smallest state of Brazil. It is a well-preserved Mata Atlântica relict of c. 700 ha, located in the municipality of Santa Luzia do Itanhy, at the southern coast of Sergipe at sea level. The Serra da Jibóia is a mountain range with a maximum elevation of 800 m, located in Bahia State, in a transitional area between the Atlantic forest and Caatinga vegetation, which is a drier and more open forest type.
The genus Malmidea in the separate family Malmideaceae was only recently described and is still incompletely known, with 41 accepted species worldwide (Lücking Reference Lücking2008; Kalb et al. Reference Kalb, Rivas Plata, Lücking and Lumbsch2011, Reference Kalb, Buaruang, Mongkolsuk and Boonpragob2012; Cáceres et al. Reference Cáceres, Santos Vieira, de Jesus and Lücking2012; Schumm & Aptroot Reference Schumm and Aptroot2012); however, many additional species, already described in this group are still hidden under Lecidea and new species are now described quite regularly.
Material and Methods
Identification and descriptive work was carried out in Itabaiana, Universidade Federal de Sergipe, using a Leica EZ4 stereomicroscope and a Leica DM500 compound microscope, and also in Soest using an Olympus SZX7 stereomicroscope and an Olympus BX50 compound microscope with interference contrast, connected to a Nikon Coolpix digital camera. Sections were mounted in tap water, in which all measurements were taken. The specimens from this study are preserved in ISE. The chemistry of the type specimen was investigated by thin-layer chromatography (TLC), using solvent A, and by observing extract recrystallization in acetone with a compound microscope (Orange et al. Reference Orange, James and White2001). Chemical reactions were applied directly on the thallus and medulla and on acetone extracts on filter paper.
The Species
Malmidea pallidoatlantica M. Cáceres & Aptroot sp. nov.
MycoBank No.: MB 801122
Similar to Malmidea atlantica (M. Cáceres & Lücking), M. Cáceres & Kalb, but with a hyaline to pale hypothecium.
Type: Brazil, Sergipe, Santa Luzia do Itanhy, Mata do Crasto, on bark of tree, c. 10 m alt., 17 April 2010, M. E. S. Cáceres & V. M. dos Santos 7017 (ISE—holotype).
A–D, Malmidea pallidoatlantica (holotype); A, habitus; B, thallus showing medulla; C, section through hymenium showing pale hypothecium (the band above the letter C; underneath is the excipulum); D, section through apothecium margin showing the distribution of yellow crystals in the excipulum (dark on the picture). E & F, Malmidea sulphureosorediata (holotype), habitus; grey thallus parts dominate the aspect in E, yellow soralia in F. Scales: A, E & F=1 mm; B=0·5 mm; C & D=50 µm.
Thallus thin, dull, grey, with numerous corticate grey warts c. 0·2 mm diam., in which the medulla is bright yellow, without prothallus. Warts hemispherical, sometimes abraded at the top, but not developing into soralia. Algae green, c. 7×5 µm.
Apothecia sessile, 0·2–0·9 mm diam.; disc flat, smooth, pinkish brown, margins rough, c. 0·2 mm wide, pale pinkish, often partly with the bright yellow medulla exposed. Hymenium hyaline, 45–65 µm high; epihymenium hyaline to very pale brownish, 4·0–6·5 µm high; hypothecium hyaline to yellowish brown, 35–50 µm thick; excipulum not corticate, mostly filled with bright yellow crystals, at least sideways and at the lower part of the excipulum underneath the apothecium, 85–125 µm thick, lumina elongated, outer cells 5·0–7·5×10·0–14·5 µm. Paraphyses unbranched, not thickened at the tips, c. 1 µm wide. Asci cylindrical, 45–60×10·0–13·5 µm. Ascospores hyaline, IKI−, simple, ellipsoid, 9·5–10·5×5·0–5·5 µm, ends somewhat pointed but not thickened.
Pycnidia not observed.
Chemistry
Thallus UV−, C−, K−, KC−, P−. Medulla K+ blood red, UV+ orange. Acetone extract deep yellow, KOH+ violet, not recrystallizing but pigment present in small droplets. TLC: anthraquinone, probably emodin.
Ecology and distribution
On smooth bark of trees in primary forest. Known only from Brazil.
Discussion
This species is close to M. atlantica (M. Cáceres & Lücking) M. Cáceres & Kalb (Cáceres Reference Cáceres2007), which mainly differs by the black hypothecium. They share the bright yellow pigment in the medulla. Both species grow together in the Mata do Crasto. The same pigment is present in the sterile M. sulphureosorediata (see below), which forms large soralia. These three species are probably closely related and known only from NE Brazil, which is one of the centres of speciation of the genus. The three species together could be referred to as the Malmidea atlantica group. Anthraquinones are generally not identifiable with certainty by TLC alone, and the identification is tentative. However, two additional characters of the substance are given: the KOH-reaction of the acetone extract and the shape as observed under a compound microscope. These characters are easily observed and may serve to distinguish the pigment in the Malmidea atlantica group from other pigments, irrespective of the identification of the compound. For instance, the most common anthraquinone that is similar in colour (dark yellow) and KOH-reaction (blood red on thallus, extract violet), physcion (=parietin), recrystallizes immediately in acetone extract, forming short, needle-like crystals in mostly star-like agglomerates.
Malmidea sulphureosorediata M. Cáceres, D. A. Mota & Aptroot sp. nov.
MycoBank No.: MB 801123
Malmidea with confluent pulverulent bright golden yellow soralia.
Type: Brazil, Bahia, Santa Teresinha, Serra da Jobóia, on bark of tree, c. 700 m alt., September 2010, M. E. S. Cáceres 7645 (ISE—holotype).
Thallus thin, dull, grey, with numerous corticate grey dots c. 0·1 mm diam., of which the medulla is bright yellow, surrounded by a hyphal prothallus line c. 0·1 mm thick. Medullary tissue soon developing into pulverulent soralia which are confluent to form soralia covering several cm2, forming a crust 0·3–0·8 mm thick. Soredia farinose, bright golden yellow, remaining mixed with grey cortical granules that particularly dominate some marginal or sheltered thallus parts. Algae green, c. 7×5 µm.
Apothecia and pycnidia unknown.
Chemistry
Thallus UV−, C−, K−, KC−, P−. Medulla and soredia K+ blood red, UV+ orange. Acetone extract deep yellow, KOH+ violet, not recrystallizing but pigment present in small droplets. TLC: anthraquinone, probably emodin.
Ecology and distribution
On smooth bark of trees in primary forest. Known only from Brazil.
Discussion
This is a sterile but very characteristic bright golden yellow sorediate lichen species. No distinct thallus warts are formed, but the soralia start as very tiny dots surrounded by a grey corticated thallus, reminiscent of some Malmidea species. Therefore, it was co-chromatographed with, and proved to be chemically identical to, the non-sorediate Malmidea pallidoatlantica (see above), a species close to M. atlantica (Cáceres Reference Cáceres2007) which mainly differs by the black hypothecium. These three species seem to be chemically identical.
Additional specimen seen. Brazil: same locality as the type, M. E. S. Cáceres 7659 (ISE).
The CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico Process 501633/2009-0) is thanked for a research grant to the first author and a student research scholarship to DAM, and the Universidade Federal de Sergipe is thanked for supporting the students VMS and DTG with a student scholarship. We are grateful to Leo Spier for performing thin-layer chromatography. AA thanks the Stichting Hugo de Vries-Fonds for a travel grant.
