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Submitted 6 March 2014, Accepted 4 April 2014, Published online 29 April 2014
Corresponding Author: Sergio P. Gorjón – e-mail – spgorjon@gmail.com 393
Rectipilus stromatoides sp. nov. (Agaricales, Basidiomycota), a new
cyphelloid fungus from the Brazilian Amazon
Gorjón SP1 and de Jesus MA2
1 Universidad de Salamanca. Salamanca, España 37007.
2 Laboratório de Patologia da Madeira. Instituto Nacional de Pesquisas da Amazônia. Manaus, Brazil 69060-001
Gorjón SP, de Jesus MA 2014 – Rectipilus stromatoides sp. nov. (Agaricales, Basidiomycota), a
new cyphelloid fungus from the Brazilian Amazon. Mycosphere 5(2), 393–396, Doi
10.5943/mycosphere/5/2/12
Abstract
A new cyphelloid species, Rectipilus stromatoides is described from the Brazilian Amazon.
It is characterized by the basidiomes disposed in a pinkish stromatic structure and microscopically
by the presence of cystidiols and the size of the basidiospores. The species is compared with the
similar species. A key to the accepted species of Rectipilus is provided.
Key words – Brazil – corticioids – South America – tropical rainforest
Introduction
Rectipilus Agerer is a cyphelloid genus with currently nine species (Agerer 1973, 1979,
Cooke 1989, Mycobank 2014, Vila et al. 1999). It is morphologically and phylogenetically very
closely related to Henningsomyces Kuntze, producing similar, more or less tubular basidiomes.
Henningsomyces produces somewhat gelatinous basidiomes (Agerer 1983) but the most important
anatomical character to separate the two genera is the branching pattern of the surface hyphae. All
species of Henningsomyces produce consistently branched surface hyphae, whereas those of
Rectipilus species are usually non-ramified, a feature which is considered taxonomically important
at the generic level among cyphelloid fungi (Agerer 1973, 1983, Bodensteiner et al. 2004). Both,
Rectipilus and Henningsomyces have non-pigmented and non-encrusted surface hyphae, a character
that morphologically separates them from a large number of cyphelloid genera (Agerer 1983). The
phylogenetic study by Bodensteiner et al. (2004) suggests that there are two clades, each including
a mixture of species of Rectipilus and Henningsomyces, so the inclusion of more species in the
analyses is still required to elucidate their phylogenetic relationships
In April 2012, the senior author was invited to the “Instituto Nacional de Pesquisas da
Amazônia” (INPA, Manaus, Brazil) to examine some collections of corticioid fungi from the
Amazonas and Roraima states of Brazil. A deviating specimen is proposed as new species in
Rectipilus based on morphological characters.
Materials & Methods
Macro- and microscopic examinations
For light microscopy studies, samples were mounted in 3% potassium hydroxide (KOH),
Mycosphere 5 (2): 393–396 (2014) ISSN 2077 7019
www.mycosphere.org Article Mycosphere
Copyright © 2014 Online Edition
Doi 10.5943/mycosphere/5/2/12
394
Melzer’s reagent (IKI). A solution of 0.1% cotton blue in 60% lactic acid (CB) was used to
determine cyanophily of basidiospore walls. Line drawings were made with a camera lucida
attachment. All the specimens are deposited in INPA.
Rectipilus stromatoides Gorjón, sp. nov. Figs 1–6
MycoBank 808176
Diagnosis – It differs from other species in the genus by the diverse basidiome disposition
in a stromatic structure. It is microscopically similar to Rectipilus erubescens, this with larger
basidiospores and to R. natalensis, the latter with smaller basidiospores.
Type –Brazil, Amazonas, Manaus, Reserva florestal A. Ducke, 27 Apr 2008, on unidentified
hardwood trunk, coll. M.A. Jesus, LPS 3536 (INPA, holotype).
Etymology – stromatoides: referred to the disposition of the basidiomes in a stroma.
Description – Basidiomes tubular, often with a median constriction, usually 200–300(–600)
µm long and about 100–150 µm in diam., arranged and embedded in a dense, and largely effused,
vivid pink coloured stroma. The external part of the basidiomes are composed by a mantle of
densely interwoven hyphae, some of them hanging loosely or in disorder and projecting, usually
tortuose or spirally curved, not encrusted nor pigmented. This external layer is about 15–20 µm
wide in transverse section. To the internal part of the basidiome the hyphae are more loosely
arranged producing the hymenium. Pore not very patent, formed by convulated hyphae in the apical
part. All hyphae with clamps, thin-walled or with distinct walls, but not distinctly thick-walled,
hyaline, not encrusted in CB, KOH, Melzer’s reagent, or water, not reacting in Melzer’s reagent.
Hymenium a palisade of basidia and cystidiols. Basidia clavate, 18–30 × 6–10 µm, with four
slender sterigmata, and a basal clamp. Cystidiols clavate to cylindrical, and usually with a more or
less elongated apical papilla, about the same size of the basidia. Basidiospores broadly ellipsoid, 5–
5.5(–6) × 3–3.5 µm, smooth, with firm to thickened walls, IKI–, CB–.
Known distribution – Known only from one collection in the type locality in the central
Amazon basin.
Other material examined – R. erubescens: N-Rhodesien, Lubalansuki Hill, Namwala, B. L.
Mitchel, 7 May 1964, on Vellozia equisedoides, (K 190550, holotype).
Discussion
As indicated above, species of Rectipilus produce small tubiform basidiomes with smooth,
non-pigmented, and non-branched surface external hyphae. Infrageneric characters contemplate
reaction of the hyphae in Melzer's reagent, shape of the surface hyphae, shape and size of the
basidiospores, shape, size and colour of the basidiomes, and presence of a more or less developed
subiculum. So far, nine species are accepted in Rectipilus: R. bavaricus Agerer, R. cistophilus
Estreve-Rav. & Vila, R. confertus (Burt) Agerer, R. davidii (D.A. Reid) Agerer, R. erubescens
(D.A. Reid) Agerer, R. fasciculatus (Pers.) Agerer, R. idahoensis (W.B. Cooke) Agerer, and R.
natalensis (W.B. Cooke) Agerer. There is an additional species listed in Rectipilus (Mycobank
2014), R. sulphureus (Sacc. & Ellis) W.B. Cooke that should be excluded from this genus because
according to the descriptions (Cunningham 1963: 311) the surface hyphae are finely encrusted and
pigmented.
Rectipilus stromatoides is morphologically similar to Rectipilus natalensis from South Africa,
by the tubiform basidiomes and spirally curved external hyphae but the latter differs in larger
yellowish basidiomes, absence of cystidiols, and smaller, thin-walled basidiospores (3.5–4.5 × 2.5–
3.5 µm) (Agerer 1973). Rectipilus stromatoides also resembles Rectipilus erubescens, described
from Zambia, sharing the pale rose colour, but this species usually has less tortuose external
hyphae, lacks cystidiols, and has larger basidiospores (6–7.5 × (4–)4.5–5.5(–6) µm) (Agerer 1979).
Based on the examination of the holotype of R. erubescens, the basidiospores have firm to
somewhat thickened-walls. In addition, the basidiome disposition in a conspicuous stroma is a
unique character of R. stromatoides.
395
Figs 1–2 – Rectipilus stromatoides. 1, Aspect of the aggregate basidiomes in the stroma. 2, Details
of individual basidiomes.
Figs 3–6 – Rectipilus stromatoides. 3, Basidiomes. 4, Basidiospores, basidia and cystidiols. 5,
Transversal section of the basidiome. 6, Longitudinal section of the basidiome. a. Basidiospores. b.
Basidia. cy. Cystidiols. e. Hyphae (external hyphae of the basidiome). h. Hyphae (generative). ls.
Longitudinal section of the basidiome. ts. Transverse section.
396
Key to Rectipilus species
1. Surface hyphae of the basidiome thick-walled and dextrinoid ........................................................ 2
1. Surface hyphae not dextrinoid ......................................................................................................... 3
2. Basidiospores ellipsoid to ovoid, 4–5.5 × 3–5 µm ....................................................... R. idahoensis
2. Basidiospores subglobose, 6.5–7.5 × 6–7 µm .................................................................... R. davidii
3. Surface hyphae more or less straight ............................................................................................... 4
3. Surface hyphae tortuose ................................................................................................................... 6
4. Basidiomes shortly tubiform, up to 0.3 mm long .......................................................... R. bavaricus
4. Basidiomes longer, ab. 1–2.5 mm long ........................................................................................... 5
5. Basidiospores 4.5–6(–7.5) × 2.5–3.5 µm, subiculum well developed ............................ R. confertus
5. Basidiospores (5–)5.5–7 × 3.5–5 µm, subiculum absent or little developed .............. R. fasciculatus
6. Basidiomes disposed in a stromatic structure ........................................................... R. stromatoides
6. Basidiomes aggregated but not embedded in a stroma .................................................................... 7
7. Basidiomes with a pale rose colour, basidiospores 6–7.5 µm long ............................. R. erubescens
7. Basidiomes with a whitish or yellowish colour, basidiospores up to 5.5 µm long ......................... 8
8. Basidiomes ab. 0.5–1 mm long, basidiospores 3.5–4.5 µm long .................................. R. natalensis
8. Basidiomes ab. 0.2–0.6 mm long, basidiospores slightly longer, 4–5.5 µm long ....... R. cistophilus
Acknowledgements
Travel and residence expenses of Sergio P. Gorjón were covered by the Brazilian government
during the visiting period through the “Conselho Nacional de Desenvolvimento Científico e
Tecnológico” (CNPq). Francisco Javier Hernández García and Bryn Dentinger, curators of SALA
and KEW respectively, managed the loan of R. erubescens. The critical review and suggestions of
an anonymous reviewer is sincerely appreciated.
References
Agerer R. 1973 – Rectipilus, eine neue Gattung cyphelloider Pilze. Persoonia 7, 389–436
Agerer R. 1979 – Typusstudien an cyphelloiden Pilzen II. Rectipilus erubescens. Sydowia 32, 1–4.
Agerer R. 1983 – Typus studien an cyphelloiden Pilzen IV. Lachnella Fr. s.l. Mitteilungen aus der
Botanischen Staatssammlung München 19, 163–334.
Bodensteiner P, Binder M, Agerer R, Moncalvo JM, Hibbett DS. 2004 – Phylogenetic diversity of
cyphelloid forms in the homobasidiomycetes. Molecular Phylogenetics and Evolution 33,
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Cooke WB. 1989 – The cyphelloid fungi of Ohio. Memoirs of the New York Botanical Garden 49,
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Cunningham GH. 1963 – The Thelophoraceae of Australia and New Zealand. Bulletin of the New
Zealand Department of Industrial Research 145, 1–359.
Vila J, Esteve-Raventós F, Llimona X. 1999 – Rectipilus cistophilus Esteve-Rav. et Vila sp. nov.,
un nuevo hongo cifeloide mediterraneo. Revista catalana de micología 22, 1–4.
www.mycobank.org – 2014.
