CC BY
46A new species of Cribraria (Myxomycetes) from Australia
S. L. Stephenson1, Yu. K. Novozhilov2, P. Wellman3
'Department of Biological Sciences, University of Arkansas, Fayetteville, USA 2Komarov Botanical Institute of the Russian Academy of Sciences, St. Petersburg, Russia
3Duffy, Australia Corresponding author. S. L. Stephenson, slsteph@uark.edu
Abstract. A new species of Cribraria, described herein as C. bicolor, appeared in moist chamber cultures on samples of the bark of Eucalyptus sp. collected at two localities in Australia. The morphology of representative specimens was examined by light and scanning electron microscopy, and micrographs of relevant morphological details of sporocarps and spores are provided. The species has a number of distinct and unique morphological features, including a glossy bright-violet globose sporotheca and a two-colored long stalk which is bright-red over the lower one-third and light yellow or lemon-yellow over the upper two-thirds. The combination of these characteristics as well as a shallow calyculus which is dark-violet when viewed under a dissecting microscope and bright red in transmitted light when mounted in lac-tophenol makes C. bicolor a well-defined morphospecies when compared to all other species of Cribraria. The stability of the taxonomic characters of the species was confirmed by an examination of a number of specimens.
Keywords: Amoebozoa, Cribraria bicolor, Myxogastria, bark, corticolous species, fungus-like pro-tists, moist chamber cultures, slime molds, taxonomy, Australia.
Новый вид Cribraria (Myxomycetes) из Австралии С. Л. Стефенсон1, Ю. К. Новожилов2, П. Вельман3
'Университет Арканзаса, Файетвиль, США 2Ботанический институт им. В. Л. Комарова РАН, Санкт-Петербург, Россия 3Даффи, Австралия Автор для переписки. С. Л. Стефенсон, slsteph@uark.edu
Резюме. Новый вид рода Cribraria, описанный как C. bicolor, был выделен во влажной камере на коре Eucalyptus sp. на севере Австралии. Морфология референсных образцов исследовалась с помощью световой и сканирующей электронной микроскопии, представлены микрофотографии соответствующих деталей спорокарпов и спор. Этот вид имеет ряд четких и уникальных морфологических признаков, в том числе глянцевую ярко-фиолетовую шаровидную споротеку и двухцветную длинную ножку, ярко-красную в нижней трети и светло-желтую или лимонно-желтую в верхней части. Комбинация этих характеристик, а также полая чашечка, темно-фиолетовая в отраженном свете под бинокуляром и ярко-красная в лактофеноле в проходящем свете микроскопа, являются четкими морфологическими признаками, которые отделяют C. bicolor от всех других видов рода Cribraria. Постоянство таксономических признаков вида было подтверждено исследованием нескольких образцов.
Ключевые слова: Amoebozoa, Cribraria bicolor, Myxogastria, эпифиты, грибообразные проти-сты, культуры во влажных камерах, слизевики, таксономия, Австралия.
https://doi.org/10.31111/nsnr/2018.52.2.379
379
Members of the genus Cribraria are among the most difficult taxa of myxomycetes to identify due to the high level of variability of morphological characters that occurs within particular morphospecies and the fact that several contradicting assessments of species boundaries exist (Adamonyte, Eliasson, 2010; Ramirez-Ortega et al, 2009). Most species of Cribraria are associated with decaying wood, most often that of coniferous trees with acidic wood, but some species are corticolous and inhabit the bark surface of living trees and lianas. The majority of the species described thus far have not yet been cultured on agar in the laboratory (Haskins, Basanta, 2008), and only certain species are known to produce sporocarps in moist chamber cultures on such substrates as bark (C. microcarpa (Schrad.) Pers., C. minutissima Schwein., C. confusa Nann.-Bremek. et Y. Yamam., C. lepida Meylan, C. tecta Hoof, and C. violacea Rex), ground litter (C. microcarpa and C. violacea) and more rarely on decaying wood (C. microcarpa, C. minutissima, C. confusa, C. lepida, C. tecta, and C. violacea). Other species such as C. zonatispora Lado, Mosquera et Beltran-Tej. have appeared in cultures prepared with decaying portions of cacti (Lado et al, 1999).
Based on the morphological species concept, 44 species of Cribraria are currently known (Lado, 2005-2017). Molecular approaches have proved to be useful in elucidating the systematic position of some myxomycete taxa at the level of genus and species (e.g., Winsett, Stephenson, 2008; Erastova et al., 2013; Novozhilov et al., 2013; Leontyev et al., 2015; Dagamac et al., 2017). However, at the present time only five sequences of the 18S rRNA gene (small ribosomal subunit, SSU), and six partial sequences of EF1A (the protein elongation factor) of C. argillacea (Pers. ex J. F. Gmel.) Pers., C. cancellata (Batsch) Nann.-Bremek., C.tenella Schrad., C. violacea, and C. vulgaris Schrad. have been submitted to GenBank (2018).
The genus Cribraria is clearly delineated from all others, and only C. argillacea (Pers. ex J. F. Gmel.) Pers. has some forms with sporocarps similar in structure to the pseudoae-thalium produced by members of the genus Lindbladia Fr. However, it should be noted that Cribraria cribrarioides (Emoto) Hatano (= Lindbladia cribrarioides (Emoto) M. L. Farr et Alexop., Tubifera cribrarioides (Emoto) Emoto) also appears to bridge the gap between Cribraria and Lindbladia. This species forms pseudoaethalia which consist of relatively few sporocarps (usually 5-40) on rather distinct stalks.
The key characters used to distinguish among the different species of Cribraria are the type of nodes of the peridial net, the ornamentation on the surface of the spores, the margin of the calyculus, and the overall structure of the peridial net. Within the genus, two morphological subgroups are well defined by the color of the spore mass. Members of the first subgroup are characterized by a lilac, violet, purple or reddish-purple spore mass, whereas members of the second subgroup have a spore mass that is light brown, pale orange or yellow. However only 8 species have been referred to the first subgroup, with the majority of species assigned to the second subgroup.
Material and Methods
Field sampling and moist chamber cultures. The specimens considered herein were obtained from moist chamber cultures prepared with samples of the bark of Eucalyptus sp. collected at two localities in Australia.
The localities where the samples were collected were georeferenced with a portable GPS device (WGS 84 mapping data). The moist chamber cultures were prepared as described in Stephenson and Stempen (1994). The type specimen was deposited in the Herbarium of the Komarov Botanical Institute RAS (LE), with a second specimen deposited in the herbarium of the University of Arkansas (UARK).
Microscopy. Air-dried sporocarps were studied with a Zeiss Axio Imager A1 light microscope with differential interface contrast (DIC), a Stemi 2000 dissecting microscope and a JSM-6390 LA scanning electron microscope in the Komarov Botanical Institute RAS (St. Petersburg). For microscopy, sporocarps were preserved as permanent slides in poly-vinyl lactophenol. The freeware program CombineZ was used to create stacked images under a Stemi 2000 dissecting microscope. Microscopic measurements were made with the program Axio Vision 4.8.0.0 (Carl Zeiss Imaging Solutions GmbH, free licence). Features (diameter and ornamentation) were determined for 10 spores per specimen for each of those examined in detail. Specimens for electron microscopy were mounted on copper stubs with double-sided sticky film and sputter-coated with gold. Color notations in parentheses are from the ISCC-NBS color-name charts illustrated with centroid colors (Anonymous, 2004-2006).
Results and Discussions
Cribraria bicolor S. L. Stephenson, Novozh. et P. Wellman, sp. nov. (Plate I)
MycoBank: MB 823359
Sporocarps scattered or in small groups, stalked, 400-600 ^m total height (Plate I: 1, 2). Sporotheca glossy vivid violet (brill.V 206 or v.V 205) globose, 100-150 ^m in diameter (Plate I: 1). Stalk long, more than two thirds of the total height of the sporocarp, stout or slightly curved in the upper part, 30-50 ^m in diameter at the base and tapering to 10-15 ^m in diameter at the apex, vivid red (v.R 11) or reddish orange (v.rO 34) over the lower one-third (Plate I: 2, 3), the upper two-thirds a light orange yellow (l.OY 70) or light yellow (l.Y 86), arising from a small discoid, membranous, strong yellow (s.Y 84) or orange yellow (v.OY 66) hypothallus. Peridium membranous, dark-violet (s.V 207 or deep V 208) under a dissecting microscope (Plate I: 2) and deep yellowish pink (deep yPk 27) in lactophenol (Plate I: 4), partially evanescent, remaining as a prominent and shallow basal calyculus and an open net in the upper portion of the sporotheca; peridial calyculus shallow, well developed, forms after apical dehiscence by disintegration of the peridium, about one third the total height of the entire sporotheca, with nearly even margins, with pronounced radial folds (Plate I: 5), outer surface granulose due to the presence of plasmodic granules, the latter about 0.5-1 ^m in diameter (Plate I: 6); nodes of the peridial net small, flattened, irregular. Spores vivid violet (v.V 205) in mass, rosy or pinkish light (pkWhite 9) in transmitted light (Plate I: 4), globose, 7-8 ^m in diameter, verruculose, with the surface ornamentation formed by scattered warts 0.2-0.3 ^m in height (Plate I: 7). Plasmodium unknown.
Holotype. Australia, Northern Territory, 26 km northwest of Katherine, 14°33'27.6"S, 132°27'30.6"E, elevation ca 170 m, forest dominated by Eucalyptus spp., sporocarps found
Plate I. Cribraria bicolor sp. nov. (from holotype LE 317311). 1 — closed sporocarp as viewed under a dissecting microscope (DM); 2 — opened sporocarps (DM); 3 — micrograph of a sporocarp as visible under a light microscope; 4 — calyculus and spores visible with a light microscope with differential interface contrast (LM, DIC, 100 x); 5 — calyculus (SEM); 6 — margin and outer surface of the calyculus with plasmodic granules marked by an arrow (SEM); 7 — collapsed spore (SEM). Scale bars: 1, 2 — 100 ^m; 3 — 50 ^m; 4, 5 — 10 ^m; 6, 7 — 1 ^m.
on sample of bark from a living Eucalyptus sp. (in moist chamber culture), 16 VI 2015, P. Wellman 1010, LE 317311.
Additional material: Australia, New South Wales, 45 km northwest of Cobar, near the carpark of Grenfell Historic Site, 30°18'24"S, 145°18'24"E, elevation 247 m, forest dominated by Eucalyptus spp., sporocarps found on sample of bark from a living Eucalyptus sp. (in moist chamber culture), 12 VIII 2013, P Wellman 864C, UARK.
Etymology. Refers to the bright red color of the bottom part of the stalk and the bright violet color of sporotheca.
Distribution: Cribraria bicolor is currently known only from the two localities in Australia.
Differentiation: The most distinctive and unique characters of C. bicolor are the glossy bright-violet globose sporotheca and a long, two-colored stalk, bright-red over the lower one-third and light yellow or orange yellow over the upper two-thirds as well as a calyculus which is dark-violet under a dissecting microscope and bright red in transmitted light when mounted in lactophenol. This color combination of the sporotheca and stalk has never before been reported for Cribraria. No described species of Cribraria with a violaceous spore mass appears to be closely related to this new species. The size and proportion of sporocarps of C. bicolor are similar to those of minute morphological forms of C. violacea, but the latter has a peridial net with large irregular nodes, a reddish dark-violet or reddish-brown stalk and a very deep calyculus, which occupies about two-thirds of the sporotheca. In C. bicolor the calyculus is shallow and occupies less than one-fourth of the sporotheca and is often reduced to merely a basal disk, and the stalk is two-colored with a bright red lower portion and a light yellow upper portion. Other species of Cribraria with a violaceous spore mass and minute sporocarps are C. zonatispora (Lado et al, 1999) and C. fragilis Meyl. (Estrada-Torres et al, 2001), but the first has elliptical spores with a smooth equatorial striated cingulum on the spore surface and the second is distinguished from all other species of the genus by its unique spores, which have smooth bands arranged in a longitudinal arc covered with prominent warts and a deep calyculus. In both species the stalk is blackish-purple or dark-brown. Other species in the genus in which the spore mass is some shade of purple, violet or lilac are C. elegans (Racib.) G. Lister (Berkeley, 1873), C. languescens Rex (Rex, 1891), C. lepida (Meylan, 1927), C. pertenuis Flatau et Schirmer (Flatau, Schirmer, 1994), C. purpurea Schrad. (Schrader, 1797), and C. tecta (Van Hoof, 2009), but all of these species have larger sporocarps with different proportions of the stalk and sporotheca, and they also differ from C. bicolor by the more or less uniform color of a dark-brown or reddish-brown stalk. None of these species or any other member of the genus has the unique combination of a bright red lower portion of the stalk and a bright-violaceous sporotheca (Table 1).
Acknowledgments
The laboratory work of the second author was carried out within the framework of the research project of the Komarov Botanical Institute of the Russian Academy of Sciences «Biodiversity and spatial structure of fungi and myxomycetes communities in natural and
anthropogenic ecosystems» (AAAA-A18-118031290108-6). In addition, we acknowledge the use of equipment of the Core Facility Center «Cell and Molecular Technologies in Plant Science» at the Komarov Botanical Institute RAS (St. Petersburg).
Table 1
Morphological characters of Cribraria bicolor and similar species of Cribraria
Taxon Characters
Net of peridium Shape of calyculus Total height of sporocarp (mm) Sporotheca (diam. in mm) Color of stalk* Color of spore mass Spore ornamentation
Cribraria bicolor + Shallow 0.4-0.6 0.1-0.2 Bright red, lemon-yellow Vivid violet Spinulose
Cribraria elegans + Deep 0.8-2 0.3-0.5 Blackish purple Brick-red to deep maroon Verruculose or smooth
Cribraria fragilis - Deep 0.2-0.3 0.1-0.2 Blackish purple Dark violet With smooth bands
Cribraria languescens + Deep 0.6-1 0.3-0.5 Blackish purple Dull reddish, copper Almost smooth
Cribraria lepida + Shallow 0.8-3 0.3-0.5 Blackish purple Violet Verruculose
Cribraria pertenuis + Shallow 0.8-1.5 0.1-0.3 Bright violet or bright brown Bright violet, tan Verruculose
Cribraria purpurea + Deep 1.5-3.5 0.5-1.5 Reddish purple Rose-purple Verrucu-lose with incomplete reticulation
Cribraria tecta - Deep 0.5-3 0.1-0.3 Black-purple Reddish brown Spinulose
Cribraria violacea + Deep 0.5-2 0.1-0.3 Reddish dark-violet Dark-violet Verrucose
Note. + — characters is present;--characters is absent; * — colors of stalk and spore mass study
under a dissecting microscope.
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