348 Persoonia–Volume43,2019

Chromosera ambigua

349Fungal Planet description sheets

© 2019 Naturalis Biodiversity Center & Westerdijk Fungal Biodiversity Institute

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KF407939 Chromosera lilacina RP: 10705 TENN:58791Chromosera lilacina GE16112Chromosera lilacina GE16115

GE18008-1

GE18008-2

GE18008-3

KF291054 Chromosera lilacina T.Borgen 86.294 (CFMR)

GU234145 Hygrocybe citrinopallida GG312:86

Chromosera xanthochroa GE16114

U66435 Hygrocybe citrinopallida Lutzoni:930731-1 DUKEChromosera citrinopallida Boertmann:2006.2 CFMR DEN:29

EU784356 Hygrocybe xanthochroa RGB K(m)55746

Chromosera xanthochroa GE16110Chromosera xanthochroa GE16113

AF261455 Chromosera cyanophylla DAOM208603AF261456 Chromosera cyanophylla DUKE1645

Chromosera cyanophylla AFTOL-ID 1684

MG050103 Chromosera sp. IMG 6589-17Chromosera cyanophylla TL-5091 (CFMR)

KJ194075 Chromosera cyanophylla WU:28831KJ194074 Chromosera cyanophylla PRM:922848

KF477303 Gloioxanthomyces vitellinus LD 1617064EU784352 Hygrocybe viola RGB K(m)20264

EU784355 Hygrocybe vitellina RGB K(m)67295

KF468712 Gloioxanthomyces nitidus DJL05NC65c4 TENN:61894Gloioxanthomyces nitidus isolate 2 GDGM41710

KF468708 Gloioxanthomyces nitidus SC 13 VT (CFMR)KF468713 Gloioxanthomyces nitidus DJL05NC65c5

Chromosera lilacina

Chromosera ambigua sp. nov.

Chromosera citrinopallida

Chromosera xanthochroa

Chromosera cyanophylla

Chromosera cyanophylla

Chromosera sp.

Gloioxanthomyces vitellinus

Gloioxanthomyces nitidus

Gloioxanthomyces sp.

FungalPlanet1005–18December2019

Chromosera ambigua Tanchaud,Jargeat&Eyssart.,sp. nov. Etymology.Theepithetreflectsthedifficultiesencounteredinseparatingthis species from morphologically close Chromosera‒fromLatinambigua (doubtful,uncertain).

Classification—Hygrophoraceae, Agaricales, Agaricomy-cetes.

Basidiomatasmall-sized,omphalioid.Pileus5–20(–30)mmdiam,initiallyconvextoplano-convexwithacentraldepressionor soon umbilicate, translucently striate up to the centre, hygro-phanous,atfirstdistinctlyviscid,entirelywhitish,yellow,lilacorwithacombinationofthesecolours.Lamellae moderately dis-tant, decurrent, concolorous with the cap, sometimes yellowish withawhitishcap.Stipe10–40×1–3mm,cylindrical,viscidwhen young, concolorous with the cap or more or less lilac espe-ciallyatthetop.Context concolorous with the surface or paler, without distinctive smell or taste.Spores(7.2–)7.4–9.3(–11)× (4.3–)4.5–5.5(–5.8)μm,Q=(1.4–)1.5–1.9(–2.1),ellipsoidoramygdaliform, sometimes with concave side or constricted in apicalpart.Basidia30–40×8–9μm,predominantly4-spored,narrowlyclavate,clamped.Cystidiaabsent.Gill trama interwo-ven,withcylindricalelementsmeasuring35–50×8–13μm,withyellowextracellulargranulesonfreshmaterial.Pileipellis athinixocutisofcylindricalhyphae,2–5(–8)μmwide.Clamp connectionspresent.

Habit,Habitat&Distribution—Insmallgroupsonpoorsan-dy and clay soil not far from ponds, in a heathland with lichens (Cladonia sp.),andsurroundedbyErica arborea, E. cinerea, Calluna vulgaris, Ulex europaeus and Pinus pinaster.Otherrare and interesting species found at the same locality included Arrhenia chlorocyanea, Hydropus moserianus, Galerina nana, Psathyrella flexispora, Plectania rhytidia and Rommelaarsia flavovirens.

Typus. france,Charente-Maritime,Saint-Gemme,LaGrande-Vergne,45.764873°N,-0.931785°E,alt.10–20m,31Jan.2016,P. Tanchaud(holo-typeGE18008, ITS,SSU, LSU,RPB2 sequencesGenBankMK645573toMK645575,MK645581 toMK645583,MK645587 toMK645589 andMK645593toMK645595,MycoBankMB830214).

Notes—Becauseof itsviscidpileusandstipe,decurrentlamellae with non-gelatinised edge but with interwoven trama and sometimes constricted and white spores, this new species fits thegenusChromosera subgenus Oreocybe (Boertmann1990,Lodgeetal.2013)thatalreadyincludesC. xanthochroa, C. citrinopallida and C. lilacina.AccordingtoBoertmann(1990,2010),Candusso(1997)andBorgen&Arnolds(2004),C. citri-nopallida and C. lilacina have an arctic and alpine distribution while C. xanthochroa can also be found in oceanic temperate areas.Becauseofitshabitat,C. ambigua could therefore be compared with C. xanthochroa, but the latter has the narrowest sporesofthesubgenus,measuringonaveragelessthan4.5µmdiam,while theaveragewidthof thesporesofournewspecieseasilyreaches5µmdiam.Ontheotherhand,consideringthethreespecieswithsporesonaveragelargerthan4.5µm,C. citrinopallida is chrome-yellow and pales to white as it ages, and therefore never presents lilac tones, while C. lilacina has a brownish orange to lilac cap and alilacstem(Consiglio1997,Hausknechtetal.2003,Consiglio&Contu2007,Boertmann2010).ButasalreadypointedbyBoertmann(1990)andConsiglio&Contu(2007),discolouredspecimens of the last two species can only be distinguished by their ecological preferences, C. lilacina being more hygrophilous than C. citrinopallida.Withoutconsideringthedifferentecolo-gical preferences of the species, yellow and lilac specimens of C. ambigua can therefore be respectively confused with C. citr-inopallida and C. lilacina, from which they differ essentially by their always clearly striate cap vs ‘sometimes short translucently striatefrommargin’or‘±translucentlystriate’(Boertmann2010,seealsoBorgen&Arnolds2004).Chromosera viola, which belongs to the subgenus Subomphalia, is readily distinguished by its completely dry pileus and stipe and broad, subglobose andnon-constricted spores (Boertmann2010, Lodgeet al.2013,Sánchez&Gibert2015).

PatriceTanchaud,2ruedesEspics,F-17250Soulignonne,France;e-mail:patrice.tanchaud@gmail.comGuillaumeEyssartier,AttachéhonoraireauMuséumnationald’histoirenaturelledeParis,180alléeduChâteau,

F-24660Sanilhac,France;e-mail:geyssartier@gmail.comPatriciaJargeat&HervéGryta,UniversitéPaulSabatier,CNRS,IRD,UMR5174EDB(LaboratoireÉvolutionetDiversitéBiologique),

118routedeNarbonne,F-31062Toulouse,France;e-mail:patricia.jargeat@univ-tlse3.fr&herve.gryta@univ-tlse3.fr

Colour illustrations. France,LaGrande-Vergne,partof theheathlandwhere theholotypewascollected.Basidiomata in situ (holotype);sporesfromholotype.Scalebars=1cm(basidiomata),10µm(spores).

PhyMLanalysis(Guindon&Gascuel2003)ofacombinedSSU,ITS,LSUand RPB2sequencedataset(3413positions,includinggaps),conductedwiththe Geneious® platform placed this species in Chromosera, closely allied to C. lilacina, C. citrinopallida and C. xanthochroa.Chromosera cyanophylla is more divergent and appears to be separated into two groups, one American andoneEuropean.Thescalebarindicatesthenumberofsubstitutionspersiteandthebootstrapsupportvalues(basedon500replicates)are indi-catedabovebranches.BluedotsareforEuropeanspecimens,reddotsforAmericanspecimensandgreendotsforAsiaticspecimens.ThealignmentandthetreeweredepositedinTreeBASE(study24563).