Introduction
The genus Pyrenula is a group of crustose lichens typically growing on smooth, shaded bark. The genus is characterized by closed, carbonized perithecioid ascomata, a hamathecium of paraphyses and brown, thick-walled ascospores. Almost all species are lichenized with Trentepohlia and occur on living bark. In its current circumscription (Harris Reference Harris1989) it comprises c. 170 species worldwide (Aptroot Reference Aptroot1991, Reference Aptroot2009, Reference Aptroot2012) and is most speciose in the tropics with, for example, 42 species in Australia (Aptroot Reference Aptroot2009) and 55 species known from the small country of Costa Rica alone (Aptroot et al. Reference Aptroot, Lücking, Sipman, Umaña and Chaves2008); however, only 10 species (see e.g. Smith et al. Reference Smith, Aptroot, Coppins, Fletcher, Gilbert, James and Wolseley2009) are known in the whole of Europe (with an additional one on the Azores). The recently revised checklist of lichenized, lichenicolous and allied fungi for Iran (Seaward et al. Reference Seaward, Sipman and Sohrabi2008) includes 632 species. Valadbeigi et al. (Reference Valadbeigi, Lumbsch, Sipman, Riahi and Maassoumi2010), Haji Moniri & Sipman (Reference Haji Moniri and Sipman2009) and Valadbeigi & Sipman (Reference Valadbeigi and Sipman2010) together add another 116 species to Iran. Among these are four Pyrenula species: P. chlorospila Arnold, P. laevigata (Pers.) Arnold, P. nitida (Weigel) Ach. and P. subelliptica (Tuck.) R. C. Harris.
Iran is one of the world's most mountainous countries, largely covered by the Iranian Plateau. Extended lowlands exist only along the coasts of the Caspian Sea and in Khuzestan. During recent collecting trips by the second and third authors, several Pyrenula species were found. The second author collected in six different provinces in areas with a wide range of ecological characteristics. The third author collected mainly in the Golestan Province close to the Caspian Sea, where a species new to science was collected as well as the three newly recorded species which are reported below. This brings the total number of Pyrenula species known from Iran up to eight. The present paper describes the new species, which was already mentioned and keyed out in Aptroot (Reference Aptroot2012), and provides a key to the Iranian species of Pyrenula, based on material from that country.
The primary forests of the Golestan Province, belonging to the type known as the Hyrcanian forest, proved to be unexpectedly rich in Pyrenula species for such a temperate (hardly subtropical) region. Golestan is part of the Mazandaran region situated in the north of Iran. It has a temperate climate, being cool and humid and known as moderate Caspian climate, which supports a lush vegetation. These special conditions are caused by the presence of the Alborz mountain range, the orientation of the mountains, the elevation of the area and the proximity to the sea.
Materials and Methods
The study is based mainly on material collected by the second author in 2004–2009 and by the third author in 2007. Most specimens are deposited in B, with some duplicates in ABL, IRAN and TARI. The morphology of all specimens was studied using an Olympus SZX7 stereomicroscope and an Olympus BX50 compound microscope with differential interference contrast optics and photomicrographs taken using an attached Nikon Coolpix 995 digital camera. Chemistry was investigated in short-wave UV.
The New Species
Pyrenula minutissima Aptroot, Valadbeigi & Sipman sp. nov.
MycoBank No: MB563998
Pyrenula ascomatis minutissimis ascosporis minutis, ad 7–9 μm longis.
Typus: Iran, Golestan, Gorgan district, 11 km SW of Gorgan, Shast Kola forest, alt. 350 m, on Carpinus in degenerated Carpinus-dominated forest, 30 October 2007, H. J. M. Sipman, M. Sohrabi, U. Søchting & R. Zare 55304a (B—holotypus; IRAN—isotypus).
(Fig. 1)
Pyrenula minutissima (holotype). A, thallus with ascomata; B, ascospores. Scales: A=0·1 mm; B=3 μm.
Thallus corticolous, olive yellowish brown, smooth, without pseudocyphellae or crystals, with trentepohlioid algae.
Ascomata numerous, black, globose to applanate, quite dispersed, not much projecting above the thallus surface, c. 0·1–0·2 mm diam. Ostiole central, minute. Hamathecium not inspersed, without crystals, IKI+ reddish. Asci disintegrating relatively early in the development. Ascospores 8 per ascus, 7–9×3·5–4·5 μm, fusiform, grey, 3-septate, not ornamented, surrounded by a thin gel layer, lumina angular, equally shaped, terminal lumina separated from the exospore by an endospore layer.
Chemistry. No secondary substances detected with TLC; UV−.
Remarks. This species is one of the smallest known in the genus, both in ascospore size and in ascoma size. In general appearance, it resembles a pycnidial morph of an Opegrapha rather than a Pyrenula because of the tiny, quite dispersed black dots on an olive thallus. It seems closest to the recently described Australian Pyrenula xanthominuta Aptroot (Aptroot Reference Aptroot2007, Reference Aptroot2009), which differs by the pseudocyphellate thallus containing crystal pockets and lichexanthone.
Pyrenula aspistea (Ach.) Ach.
Syn. Meth. Lich. 123 (1814); type: Guinea (H–ACH, syntypes, n.v.).
Selected specimens examined. Iran: Golestan: Gorgan district, 11 km SW of Gorgan, Shast Kola forest, alt. 350 m, on Carpinus in degenerated Carpinus-dominated forest, 2007, H. J. M. Sipman, M. Sohrabi, U. Søchting & R. Zare 55301a & 55302 (B, IRAN); Gorgan district, 14 km SW of Gorgan, Baran Kuh forest, alt. 500–700 m, on Fagus orientalis in primary deciduous forest in valley along stream, 2007, H. J. M. Sipman, M. Sohrabi, U. Søchting & R. Zare 55316 (B, IRAN). Gilan: 65 km on the road from Khalkhal to Asalem, alt. 150 m, 2007, T. Valadbeigi 5848 (ABL, TARI).
Pyrenula nitidula (Bres.) R. C. Harris
In A. Aptroot, P. Diederich, E. Sérusiaux & H. J. M. Sipman, Bibliotheca Lichenologica 64: 165 (1997); type: Puerto Rico (n.v.).
Specimen examined. Iran: Golestan: Gorgan district, 11 km SW of Gorgan, Shast Kola forest, alt. 350 m, on Carpinus in degenerated Carpinus-dominated forest, 2007, H. J. M. Sipman, M. Sohrabi, U. Søchting & R. Zare 55302a (B, IRAN).
Pyrenula santensis (Nyl.) Müll. Arg.
Flora 65: 400 (1882); type: USA, South Carolina, Santee Canal, H. W. Ravenel (H—Nyl, holotype, n.v.).
Note. This species has recently been synonymized with Pyrenula balia (Krempelh.) R.C. Harris (Aptroot Reference Aptroot2012).
Selected specimens examined. Iran: Golestan: Gorgan district, 14 km SW of Gorgan, Baran Kuh forest, alt. 500–700 m, on Fagus orientalis in primary deciduous forest in valley along stream, 2007, H. J. M. Sipman, M. Sohrabi, U. Søchting & R. Zare 55315, 55325 & 55327 (B, IRAN).
Key to the species of Pyrenula in Iran
1 Ascospores 30–36 μm long, with unequal lumina; middle lumina elongated; hamathecium at least partly inspersed with hyaline oil globules ... P. subelliptica
Ascospores <30 μm long, with equally shaped lumina; hamathecium not inspersed ... 2
2(1) Ascomata in majority 0·1–0·4 mm diam. ... 3
Ascomata in majority 0·4–1·2 mm diam. ... 6
3(2) Ascospores 23–30 μm long, with equally shaped lumina; hamathecium not inspersed ... P. chlorospila
Ascospores 7–21 μm long ... 4
4(3) Ascospores 17–21 μm long, with unequal lumina; terminal lumina closely appressed to the outer ascospore wall ... P. nitidula
Ascospores 7–16 μm long, with equally shaped lumina; terminal lumina separated from the exospore by an endospore layer ... 5
5(4) Ascospores 11–16 μm long; ascomata c. 0·2–0·4 mm diam. ... P. aspistea
Ascospores 7–9 μm long; ascomata c. 0·1–0·2 mm diam. ... P. minutissima
6(2) Hamathecium with orange-red crystals, KOH+ purple-red soluble pigment; ascospores 20–27 μm long ... P. nitida
Hamathecium without coloured crystals, KOH− ... 7
7(6) Ascospores 14–16 μm long; thallus generally olive-green ... P. santensis
Ascospores (15–)17–22 μm long; thallus whitish grey ... P. laevigata
Discussion
The first indication of a tropical pyrenocarpous element in the lichen flora of Iran was the report of Lithothelium obtectum (Müll. Arg.) Aptroot (identified by the first author, and reported by Valadbeigi & Sipman Reference Valadbeigi and Sipman2010), known to be pantropical and common only in India (Aptroot Reference Aptroot1991). It was also found in Iran along the Caspian coast in the zone of the Hyrcanian forests. All of the present additions to the Pyrenula flora of Iran are distinctly tropical, while the species already reported are generally thought of as Atlantic European, with the surprising exception of the representative of a North American element, viz. Pyrenula subelliptica (Harris Reference Harris1989).
The second author thanks Siahgis Zolfaghari for good companionship during the field work.
