Moelleriella, and Samuelsia - CBS

Ne o t r o p i c a l Hy p o c r e l l a, Mo e l l e r i e l l a, a n d Sa m u e l s i along. Moelleriella gaertneriana, M. boliviensis, M. guaranitica, M.castanea, M. globosa, and M. disjuncta have small part-spores (ca.5–8 µm long); and M. phyllogena, M. umbospora, and M. basicystishave large part-spores (ca. 17–25 µm long). Moelleriella castaneahas the smallest part-spores and M. umbospora has the largest.The shape of the anamorphic stromata is highly variable,sometimes even within species. Anamorphic stromata may bepulvinate with pezizoid projections; tuberculate; hemiglobose;scutate; thin pulvinate, almost effuse; or thin pulvinate/effusewith pronounced erect or embedded tubercles. Conidiomata ofMoelleriella are pycnidial to acervular, with one to several loculesper stroma. The conidiomata are more commonly found than theperithecia, but sometimes both can be found in the same stroma(e.g. M. turbinata, M. evansii, M. libera, M. sloaneae, and M.ochracea, among others). The pycnidial locules can be simpledepressions of the surface with or without distinct rims, or wideopenlocules that resemble half-embedded bowls (e.g. M. turbinata).The arrangement of the pycnidia in the stroma can be scattered(e.g. most species), circular (e.g. M. libera and M. phyllogenaand related species), or central (e.g. M. epiphylla, M. evansii, andM. globosa). Filiform paraphyses are present in some species,but are not a reliable character because sometimes they are notproduced in culture. Conidiophores are formed in a compactlayer, which sometimes makes it difficult to separate phialides andcharacterise them. Phialides are formed from short conidiophoresthat are sometimes indistinct, branching once monochasial, twicemonochasial, monoverticillate, or two level monochasial (Seifert1985). In most cases, the same species might have more thanone type of conidiophore branching. Phialides are generallyflask-shaped to slender and cylindrical (ca. 10–15 × 2.5–3 µm).Conidial masses are in bright colours ranging from reddish brownto orange to deep or pale yellow. Conidia are hyaline, unicellular,and generally fusoid, ca. 9–13 × 2.5–4 µm, with a length/width ratio(l/w) ca. 3–4.5. Some species, such as M. epiphylla, M. turbinata,and M. globosa have ovoid conidia with acute ends (l/w 2–2.5).The extent of variation in appearance of colonies on PDA at 25ºC after ca. 3 wk of growth is somewhat significant at the specieslevel. Most of the species studied produce slow-growing spreadingcolonies, minutely tomentose or compact and leathery. The coloniesare initially white and then may turn greyish white, yellowish, ororange. The fastest growing species do not reach more than 35mm in 3 wks. Generally, phialides in PDA at 25 °C are smallerthan phialides from stromata. However, M. epiphylla has slightlylarger phialides in PDA at 25 °C. Conidia in PDA at 25 °C afterthree wk are also generally smaller than conidia from stromata.However, M. macrostroma has significantly larger conidia in PDA at25 °C. A hirsutella-like synanamorph was observed in cultures ofM. turbinata and M. epiphylla. This type of synanamorph has alsobeen observed in M. insperata (Liu et al. 2005). Capilliconidiophoresand capilliconidia have been also observed developing from asciand conidia on PDA at 25 °C. Production of diffusing pigment wasnot observed in the cultures examined.Hypocrella/Aschersonia morphologyStroma morphology in Hypocrella is significantly more conservedthan in Moelleriella. The stromatal size of Hypocrella speciestreated in this study does not vary greatly and ranges from 1.5–2mm diam. The colour of the stromata of the species studiedis in shades of yellow, orange, or green. Pale yellow is the mostcommon colour. Hypocrella disciformis and H. viridans have greenstromata; these species are phylogenetically related (Figs 1–2). Thewww.studiesinmycology.orgshape of the stromata is generally pulvinate with a narrow base.The surface of the stroma can be dull/matt, opaque, glabrous,or roughened. Hypocrella hirsuta has synnematous projectionson the surface of the stroma. These projections correspond to ahirsutella-like synanamorph. Hypothalli are present in some of theexamined species, i.e. H. hirsuta, and sometimes in H. viridansand H. disciformis (but are lacking in culture). The majority of thespecies examined have a reaction to 3 % KOH on the tissue ofthe stromata. Most of the species turn brown when KOH is added,except H. citrina. Hypocrella discoidea becomes reddish when KOHis added. The tissue structure of the stroma surface is highlyconserved among the examined species. All species studied havethe tissue type referred to as textura intricata or epidermoidea. Thecell walls of the stromatal hyphae are ca. 2 µm thick. The innertissue below the outermost layer of the stroma is also texturaepidermoidea to intricata.Perithecia in Hypocrella are generally completely embedded inthe stroma or, sometimes half-embedded. When the stroma containsperithecia and pycnidia, the perithecia are towards the edges ofthe stroma, with pycnidia towards the centre. The ostioles are inshades of orange or brown. In longitudinal section, perithecia areelongated to subglobose, sometimes globose, with walls composedof 3–4 layers of highly compacted, thin-walled cells.The asci are cylindrical and sometimes swollen in the middle.The ascus cap is thickened (ca. 1–6 µm) and with a conspicuousring. Hypocrella viridans and H. citrina have thin ascus caps (ca.1–1.5 µm); and H. hirsuta and H. aurantiaca have thick ascus caps(ca. 4–6 µm). The ascospores are always filiform or long fusiform,hyaline and smooth. For the most part, the species studied haveascospores ca. 75–140 × 2–5 µm. Hypocrella citrina has shortascospores (ca. 110–115 µm long); and H. aurantiaca, and H.hirsuta have long ascospores (ca. 120–140 µm).The shape of the anamorphic stromata is pulvinate,sometimes almost discoid, like that of the stromata containing theteleomorph. Conidiomata of Hypocrella are pycnidial, with oneto few (ca. 2–5) locules per stroma. The conidiomata are morecommonly found than the perithecia, but sometimes both can befound in the same stroma (e.g. H. viridans and H. disciformis). Thepycnidial locules are flask-shaped with narrow openings. Thearrangement of the pycnidia in the stroma is circular. Paraphyseswere present in all the species studied. Conidiophores are formedin a compact layer, which sometimes makes it difficult to separatephialides and characterise them. Phialides are formed from shortconidiophores that can be indistinct, branching once monochasial,twice monochasial, monoverticillate, or two level monochasial(Seifert 1985). In most cases, the same species might have morethan one type of conidiophore branching. The phialides are flaskshapedto slender and cylindrical (ca. 12–20 × 2–2.5 µm). Exudedconidial masses are less common, but when present they arein shades of greyish yellow. Conidia are hyaline, unicellular, andfusoid, ca. 13–30 × 2–6 µm, with a length/width ratio (l/w) ca. 5–6.Hypocrella aurantiaca, H. hirsuta, and H. citrina have the largestconidia (ca. 20–30 µm long).The extent of variation in appearance of colonies on PDAat 25 ºC after ca. 3 wk of growth is somewhat significant at thespecies level. However, many of the cultures examined did notsurvive storage at 8 °C and many did not produce conidia inculture. Of the few colonies that grew, the growth rate is slow andthe colonies are tomentose compact and leathery. The coloniesare initially white and then may turn greyish brown or light brown.Generally, phialides in PDA at 25 °C are smaller than phialides17