Micorrizas

ISSN (print) 0093-4666

© 2011. Mycotaxon, Ltd.

ISSN (online) 2154-8889

MYCOTAXON
Volume 116, pp. 161–169

doi: 10.5248/116.161

April–June 2011

Orbispora gen. nov., ancestral in the
Scutellosporaceae (Glomeromycetes)
Fritz Oehl1*, Danielle Karla Alves da Silva2,
Leonor Costa Maia2, Natália Mirelly Ferreira de Sousa2,
Helder Elísio Evangelista Vieira2 & Gladstone Alves daSilva2
Federal Research Institute Agroscope Reckenholz-Tänikon ART,
Ecological Farming Systems, Reckenholzstrasse 191, CH-8046 Zürich, Switzerland
2
Departamento de Micologia, CCB, Universidade Federal de Pernambuco,
Av. Prof. Nelson Chaves s/n, Cidade Universitária, 50670-420, Recife, PE, Brazil
* Correspondence to: fritz.oehl@art.admin.ch
1

Abstract — Scutellospora pernambucana and S.projecturata are transferred into
Orbispora, our proposed new genus in the arbuscular mycorrhiza-forming Scutellosporaceae
(Glomeromycota). Orbispora is recognized by spores formed terminally on sporogenous
cells and three spore walls with single mono-lobed hyaline to subhyaline germination orbs
on the inner ‘germinal’ wall that appear identical to the orbs in Kuklospora colombiana,
K.kentinensis, and a few Acaulospora species. DNA sequence analyses show the two Orbispora
species as ancestral within the sporogenous cell-forming Glomeromycetes. An updated key
summarizes the morphological differences among species in the Scutellosporaceae.
Key words — evolution, Gigasporineae, Gigasporaceae, molecular phylogeny, rDNA

Introduction

Recently, the genus Scutellospora C. Walker & F.E.Sanders 1986 was
revised, and Gigasporaceae sensu lato was divided into four families based on
phylogenetic data congruent with spore wall morphology (especially that of
germination shields) and spore germination: Gigasporaceae, Scutellosporaceae,
Racocetraceae and Dentiscutataceae (Oehl et al. 2008, Goto et al. 2010a).
Scutellosporaceae comprised a single genus, Scutellospora. Two species ofthe
revised genus were found to have three spore walls and mono-lobed, orbital,
hyaline to subhyaline germination orbs on the inner, ‘germinal’ wall, with a single
germ tube initiation from where one to (rarely) two germ tubes emerge during
germination to penetrate the outer walls (Silva et al. 2008; Oehl et al. 2008). The
fact that such germ orbs and germination features were knownpreviously only

162 ... Oehl & al.
for a few ancestral species in the Acaulosporaceae — e.g., Kuklospora colombiana
(Spain & N.C. Schenck) Oehl & Sieverd. 2006, K. kentinensis (C.G. Wu & Y.S.
Liu) Oehl & Sieverd. 2006, Acaulospora mellea Spain & N.C. Schenck 1984
(Spain 1992, Schenck et al. 1984, Sieverding & Oehl 2006, Silva et al. 2008) —
suggesting a close relationship between Acaulosporaceaeand Scutellosporaceae
sensu Oehl et al. 2008 (e.g. Silva et al. 2008).
During the current study we investigated whether these two species,
Scutellospora pernambucana and S. projecturata, might be ancestral within
Scutellosporaceae. To test this hypothesis, partial LSU rDNA sequences were
generated for S. pernambucana, and the phylogenetic position of S. projecturata
was analyzed from almostcomplete 18S rDNA sequences obtained from public
databases. Because our hypothesis was confirmed and morphological and
phylogenetic analyses are congruent, we segregate the two species from the
other Scutellospora species that also have hyaline to subhyaline, but bi-lobed
and generally violin-shaped, germination shields, and we transfer both species
into a new genus within theScutellosporaceae.
Material & methods
Morphological analyses

Oehl et al. (2008) and Silva et al. (2008) published the morphological analyses
relevant for this study. Scutellospora pernambucana (type species for the new genus) was
found in several sites of the Caatinga and Mata Atlantica biomes (e.g. Goto et al. 2010b)
in Igarassu, Araripina, São Bento do Una, and Abreu e Lima (all Pernambuco State),
São...