Introduction
Sergipe is the smallest state in Brazil, and its coast was originally covered by the Atlantic rainforest, or Mata Atlântica. Today, only scattered forest patches still remain untouched in a few conservation units throughout the state, although most are part of private properties. These small Mata Atlântica fragments are located in the coastal zone of Sergipe, comprising a range of only c. 40 km wide, and are surrounded by sugar cane plantations. In spite of the reduced amount and size of natural areas in the state, a few recent lichen inventories in Sergipe have revealed a surprisingly rich and until now unknown lichen diversity (Cáceres Reference Cáceres2007).
The Serra de Itabaiana, with c. 3 400 ha and an altitude range of 195–680 m, is located between the municipalities of Areia Branca and Itabaiana (Mendes et al. Reference Mendes, Gomes and Alves2010), in the mesoregion of the Agreste, and comprises three geomorphological units: the ridges Cajueiro, Comprida and Itabaiana (Carvalho & Vilar Reference Carvalho, Vilar, Carvalho and Vilar2005).
During a lichen survey in forest remnants around the Serra de Itabaiana National Park, an undescribed species of the genus Eugeniella was found in a forest patch from Fazenda Cafuz, a private property which still preserves part of the original Mata Atlântica cover.
The genus Eugeniella in the family Pilocarpaceae was recently described to accommodate a few species with an excipulum which is composed of large, moniliform hyphae with constricted septa, densely incrusted with minute hyaline crystals, and mostly unbranched paraphyses. The genus is still incompletely known, with only seven species worldwide (Lücking Reference Lücking2008). Two further undescribed species were reported from St Helena (Aptroot Reference Aptroot2008) and Costa Rica (Lücking Reference Lücking2008). Further Eugeniella species may well have been originally described in the genus Bacidia (Lücking Reference Lücking2008).
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 also 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 (Orange et al. Reference Orange, James and White2001).
The Species
Eugeniella nigrodisca M. Cáceres, D. S. Andrade & Aptroot sp. nov.
MycoBank No.: MB 801121
Eugeniella differing from E. ortizii by the clavate, consistently 7-septate ascospores of 25–42×2·5–5·0 µm and the occurrence on bark.
Type: Brazil, Sergipe, Areia Branca, Fazenda Cafuz, on bark of tree, c. 340 m alt., 8 November 2011, M. E. S. Cáceres & D. S. Andrade 10177 (ISE—holotype).
(Fig. 1)
Fig. 1. Eugeniella nigrodisca (holotype). A, habitus; B, section through apothecium margin; C, excipulum showing moniliform hyphae; D, ascus (in IKI); E & F, ascospores. Scales: A=1 mm; B=50 µm; C–F=10 µm. In colour online.
Thallus thin, not corticate, dull, starting as isolated granules of c. 50 µm, soon aggregating to form a nearly continuous greenish grey crust on a thin whitish byssoid hypothallus, greenish grey. Algal cells green, c. 7 µm diam.
Apothecia sessile, 0·2–0·6 mm diam., round to mostly lobate when older; disc flat, dull, deep yet black, margin white, dull, crenate, c. 0·1 mm wide. Hymenium hyaline, IKI+ blue, 60–75 µm high; paraphyses only branched in the epihymenium; hypothecium blackish brown, in the centre of the apothecium up to 50 µm high, tapering out to the periphery; excipulum hyaline, 20–35 µm wide, composed of large (cells 7–12×4·5–5·5 µm), moniliform hyphae with constricted septa, densely incrusted with minute hyaline crystals. Ascus containing 8 ascospores, tip in IKI with two layers of dense staining. Ascospores hyaline, clavate, consistently 7-septate, 25–42×2·5–5·0 µm, lower end attenuated but tips rounded.
Pycnidia not observed.
Chemistry
Thallus UV−, C−, K−, KC−, P−. No substances detected with TLC.
Ecology and distribution
On smooth bark of trees in primary forest. Known only from Brazil.
Discussion
The characteristic excipulum of the genus, which is composed of large, moniliform hyphae with constricted septa, is illustrated here for the first time. The new species is not identical with any of the known species of Eugeniella and seems to differ from all species described from Brazil in the similar genus Bacidia by Ekman (Reference Ekman1996), Malme (Reference Malme1935) and Vainio (Reference Vainio1890). Most Eugeniella species known so far have either submuriform or 3-septate ascospores. Eugeniella ortizii (Lücking) Lúcking et al. has ascospores of 17–26×4·5–5·5 µm with (3–)5–7) septa (Lücking Reference Lücking2008). The new species described here has larger ascospores that are consistently 7-septate.
The CNPq [Conselho Nacional de Desenvolvimento Científico e Tecnológico (Process 501633/2009-0)] is thanked for a research grant to the first author. The Universidade Federal of Sergipe is thanked for a student research scholarship to DSA and GKO. Leo Spier is thanked for performing thin-layer chromatography. AA is grateful to the Stichting Hugo-de Vries-Fonds for a travel grant.
