Phylogenetic and morphological circumscription of the Orbilia aurantiorubra group


1 Departamento de Biología Vegetal (Botánica), Universidad de La Laguna, Tenerife 38201, Canary Islands, Spain.
2 Blaihofstr.42, D-72074. Tübingen. Germany.
3 Departamento de Biodiversidad Molecular y Banco de ADN. Jardín Botánico Canario “Viera y Clavijo” – Unidad Asociada CSIC, Cabildo de Gran Canaria, Spain.
4 Universität Tübingen, Fachbereich Biologie, Auf der Morgenstelle 5, D-72076 Tübingen, Germany.


The phylogeny of Orbilia aurantiorugra and related species is inferred from ITS sequence data. Orbilia aurantiorubra is redefined according to vital taxonomy. Integrated analyses of molecular and morphological data, and ecological (e.g. substrate) and geographical origin suggest the existence of three new species, which are described in this paper: Orbilia xanthoguttulata from Europe, O. succulenticola from the Canary Islands, and O. jugulospora from Ethiopia (Africa) and Taiwan (Southeast Asia).


The genus Orbilia Fr. (Orbiliaceae Nannf.) was traditionally placed in the order Helotiales Nannf., and considered as a low diversity group (Spooner 1987). The advantages of using living cells (Baral 1992) for the taxonomic study of the Orbiliaceae have dramatically improved the knowledge of this family in the last two decades. Indeed, the family Orbiliaceae has undergone many changes since Baral & Marson (2001) introduced the genus Hyalorbilia, based on a
small group of species previously included in Orbilia. Thus, in 2001 the Orbiliaceae comprised two genera and ~35 spp. (Kirk et al. 2001). In 2003 the family was segregated from the Leotiomycetes to constitute an order and class of its own, the Orbiliales and Orbiliomycetes (Eriksson et al. 2003). Further molecular studies found that this class formed an early diverging major clade within Pezizomycotina (Spatafora et al. 2006).

Thus far, Orbilia is represented by ca. 58 species worldwide, principally wood-saprobic fungi, particularly common in temperate regions (Kirk et al. 2008, Cannon & Kirk 2007). However, the forthcoming world monograph of Orbiliomycetes (Baral et al. in prep.) will recognize about 400 species within this genus, most of which are adapted to semihumid to arid, subtropical to tropical environments. Despite this considerable increase in species number,
there is still a substantial lack of knowledge concerning host or habitat preferences and biogeography for many of the recognized species. Not surprisingly, this current lack of elementary data has impeded the assessment of many important aspects bearing on the evolutionary biology and systematic of this group.

Orbilia aurantiorubra Boud. is easily recognizable by its bright orange-red apothecia, and geniculate based helicoid spores containing narrowly tear-shaped spore bodies. It is briefly described by Boudier (1907) and appears in his Icones mycologicae (Boudier 1904–10). This species tolerates desiccation, and occurs throughout the year on different substrates in temperate, continental to Atlantic areas of Europe and West Africa (rarely in Mediterranean
areas), between 0–1650 m (Baral et al. ined.). Specimens related to O. aurantirubra have ascospores variation between (7.5–)8–14.5(–16) × 1.1–1.8 µm and spores bodies between (1.8–)2.5–4.5(–5.5) × (0.5–)0.7–1.1(–1.3) µm. Some variation in spore dimensions correlated with host or geographical origins in O. aurantiorubra were noticed (Karasch et al. 2005, Priou 2005, Spooner 2001). Species considered as widespread fungi, usually showed a restricted distribution after taxonomical review (Stadler et al 2004; Baral 1984). The correlation between ascospore size and host has been evidence for species differentiation (Petrini et al. 1987). Generally, morphological variation observed in species can  now be assessed using molecular phylogenetic approaches; recent application in ascomycetes taxonomy include, e.g., Hustad et al. (2013); or Zhao-Qing & Zhuang (2013) and Hyde et al. (2013).