Introduction
Bactrospora is a widespread but seldom abundant genus of the Roccellaceae, occurring usually corticolous, equally in tropical and temperate regions, in the latter often on the sheltered or overhanging side of trees. Species of this genus have black, sessile, round apothecia with filiform ascospores, usually without gel binding the paraphysoids. The thallus is usually inapparent or poorly developed, and the genus is often overlooked or not collected by lichenologists who mistake it for non-lichenized fungi.
So far 30 species of Bactrospora are known, 20 of which were treated in the revision of the genus by Egea & Torrente (Reference Egea and Torrente1993), the others described in subsequent papers (Egea & Torrente Reference Egea and Torrente1995; Egea et al. Reference Egea, Sérusiaux, Torrente and Wessels1997; Kantvilas Reference Kantvilas2004; Lendemer Reference Lendemer2004; Ponzetti & McCune Reference Ponzetti and McCune2006; Sparrius et al. Reference Sparrius, Saipunkaew, Wolseley and Aptroot2006; Aptroot et al. Reference Aptroot, Saipunkaew, Sipman, Sparrius and Wolseley2007; Berger & Aptroot Reference Berger and Aptroot2008). Many species are known from one country only, but the known ranges of some species have expanded recently when additional reports were published (e.g. notably from Brazil by Cáceres Reference Cáceres2007). Interestingly, endemics occur in very different biomes ranging from temperate rainforest in Tasmania to dry coasts in Chile and tropical rainforest in Malaysia or Brazil.
During studies on lichen ecology and diversity by the first author in mountain forest in Pernambuco State in the north of Brazil, an undescribed species was encountered which is described below. Because many new species have been recently described in the genus, making the key in Egea & Torrente (Reference Egea and Torrente1993) increasingly incomplete, an artificial world key to all currently known species of Bactrospora is given here together with their known distribution ranges. We studied material of the majority of the known species.
The new species was found in Caruaru, one of the few places with mountain forest in the rather lowland state of Pernambuco. The lichens of these mountain forests, called Brejo de Altitude and part of the former more extensive Atlantic Rainforest biome (Thomas & Barbosa Reference Thomas and Barbosa2008), are not yet well studied. The only lichen records from Brejo de Altitude are those made by Cáceres (Reference Cáceres2007).
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 URM. The chemistry of the type specimen was investigated by thin-layer chromatography (TLC) using solvent C (Orange et al. Reference Orange, James and White2001). Iodine reactions (IKI/KOH) were observed by applying IKI (undiluted Lugol's) after pretreatment with 10% KOH.
The New Species
Bactrospora angularis Sobreira, Aptroot & M. Cáceres sp. nov.
MycoBank No.: MB 811036
Corticolous Bactrospora with apothecia that usually have an irregular outline and transversely (19–)28–35-septate, filiform ascospores of (85–)120–150 × 5–7 μm, with some constrictions.
Type: Brazil, Pernambuco, Caruaru, Brejo dos Cavalos, Velha Joana trail, 8°22′S, 36°02′W, on bark of tree, 877 m alt., 14 November 2013, P. N. B. Sobreira 345 (URM—holotype).
(Fig. 1)
Bactrospora angularis, holotype. A, habitus; B, superficial filaments of a trentepohlioid alga; C, young ascospore; D, mature ascospore. Scales: A=0·1 mm; B-D=10 μm. In colour online.
Thallus crustose, not corticate, slightly shiny, greyish green, closely following the bark surface, covered by superficial trentepohlioid algal filaments which may be symbiotic or epiphytic, surrounded by a black prothallus line. Superficial trentepohlioid filaments hyaline, septate, unbranched, 55–120 × 4·5–5·5 μm, wall very rough; tip with thickened wall; trentepohlioid cells inside the thallus ellipsoid.
Apothecia numerous, dispersed, sessile, round to usually irregular in outline, occasionally elongate, 0·2–0·5 mm diam.; disc flat, chocolate brown, dull, margin chocolate brown, c. 0·1 mm wide, not or only slightly raised above the disc. Excipulum carbonaceous, IKI/KOH–, at the sides up to c. 100 μm thick. Hymenium not inspersed, 200–250 μm high; subhymenium IKI/KOH–; paraphyses little branched, apices not swollen. Asci 180–200 × 18–26 μm. Ascospores 8 per ascus, hyaline, filiform, (19–)28–35-septate, (85–)120–150 × 5–7 μm, cells generally wider than long (except when young), each ascospore with a few constrictions, lower end rather pointed, upper end rounded.
Pycnidia not observed.
Chemistry
No spot reactions. TLC: no substances.
Ecology and distribution
On smooth bark of trees in Brejo de Altitude forest. Known only from Brazil.
Discussion
It is difficult to ascertain whether the omnipresent superficial trentepohlioid filaments are symbiotic or epiphytic. A similar case is Bactrospora incana Egea & Torrente, the type of which (we studied a large isotype in M) is also covered by trentepohlioid filaments. Symbiotic superficial filamentous trentepohlioid algae are rare, but known in e.g. Microtheliopsis uleana Müll. Arg.. In internal characters the new species is closest to B. pleistophragmia (Nyl.) Egea & Torrente, which differs by the positive reaction in IKI after pretreatment with KOH.
PNBS thanks the Fundação de Amparo à Ciência e Tecnologia do Estado de Pernambuco (FACEPE) for a Masters scholarship. AA thanks the Stichting Hugo de Vries-Fonds for travel support. Damien Ertz is thanked for discussions on species characters in the genus and for making the collections in BR avaliable for study by AA. MESC is grateful to CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico) for a research grant (Processo 311706/2012-6).
