Contribution to the taxonomy of Sistotremastrum (Trechisporales, Basidiomycota) and the description of two new species, S. fibrillosum and S. aculeocrepitans Author Gruhn, Gérald Office National des Forêts, Réseau mycologie, 5 avenue Mirandol, F- 48000 Mende, France Author Alvarado, Pablo ALVALAB, La Rochela 47, E- 39012 Santander, Spain Author Hallenberg, Nils Hessgade 35, DK- 5500 Middelfart, Denmark Author Roy, Mélanie Laboratoire évolution et diversité biologique, Université Paul Sabatier (UPS) - CNRS, Toulouse, France, 118 route de Narbonne, F 31062 Toulouse, France Author Courtecuisse, Régis Université de Lille (Laboratoire des sciences végétales et fongiques - LSVF), B. P. 83, F- 59006 Lille Cedex, France text Phytotaxa 2018 2018-11-27 379 1 27 38 http://dx.doi.org/10.11646/phytotaxa.379.1.2 journal article 10.11646/phytotaxa.379.1.2 1179-3163 13724819 Sistotremastrum aculeocrepitans G. Gruhn & P. Alvarado , sp. nov . ( Figs. 5 and 6-A ) MycoBank : MB 823880 Diagnose : similar to Sistotremastrum fibrillosum , differs from other Sistotremastrum species because of its fibrillose basidiome with numerous wide cords and odontoid hymenial surface, but presents a ceraceous context. Holotype : LIP 0001408 Isotypes : GB , GG MAR 15-007 Paratypes : LIP 0001409, 0001410, 0001411, 0001412, all of them duplicated in GB and GG Etymology : aculeocrepitans epithet refers to the subtle sound produced when cutting aculei to prepare mounts, caused by their ceraceous texture. From Latin aculeus : aculei and crepitare : to crack (sound). FIGURE 5. S. aculeocrepitans (holotype). A: spores. B: hyphidia. C: basidia. bar = 10 μm. Basidiome resupinate, effused, up to 25 × 15 cm , adnate, easily detached from the wood substrate, young parts cream to yellowish when fresh, mature parts darkening, ochraceous to light orange, not changing in herbarium collections except for apical aculei which are cream colored, not changing in KOH (10%), odontoid, numerous (6-10/mm) aculei with wide bases, becoming cylindrical, with rounded apex at the tip, some of them agglutinated at the base (2 to 5), length 200–1000 μm long, × 70–200 μm in diam., ceraceous, a characteristic sound is made when aculei are separated from the subiculum. Context continuous, thin, 20−50 μm thick. Margin porulose, with ceraceous smooth cords, ochraceous, 100–200 μm wide. Young specimens have pure white cords. Hyphal system monomitic. Hyphae in cords and core of aculei are hyaline, 4–5 μm in diam., with slightly thickened to thick walls (up to 1 μm), clamp connections present at all septa, agglutinated but easy to observe, hyphal cells sometimes short, 6–10 μm long, sometimes ampullate, up to 6 μm wide, without crystals. Subhymenial hyphae with thin wall, 3−4 μm in diam. Aculei sterile at the apex, with hyphidia. Despite a dense hymenium and a ceraceous context, they are easy to dissociate with a tap on a mount. Hyphidia present in the sterile apex of aculei but rare in hymenium, flexuous, with irregular shape, tapering, with rounded apex, clamped at the base, thin-walled, hyaline, smooth, 15−30 × 3−4 μm. Basidia clavate to cylindrical, with a median constriction, tabular, (12−)14−19 × 5−6 μm, with a basal clamp, always 4-sterigmate, sterigmata at first rounded, then slender, up to 4 μm long. Spore print white. Basidiospores shortly cylindrical to ellipsoid, with adaxial side flat or slightly depressed, walls hyaline, thin, smooth, 4.5−6.0(−6.5) × 2.5−3.0(−3.5) μm, Qm=2.0, non-cyanophilous, not reacting to Melzer’s reagent. Note: Paratypes has been defined for S. aculeocrepitans (see below), all collected the same day, in the same place, on the banks of Anse Couleuvre river, which is a very rainy place in North West side of Martinique island, in different clusters of Bambusa vulgaris between ten to fifty meters from each other. All of these collections has similar ITS and LSU sequences. Specimens examined: FRANCE : French West Indies , Martinique : Five collections, collected same place and same day, LIP 0001408 ( holotype ) and GB ( isotype ) and GG MAR15-007 ( isotype ), LIP 0001409 (& GG MAR15- 008 & GB ) ( paratypes ), LIP 0001411 (& GG MAR15-009 & GB ) ( paratypes ), LIP 0001412 (& GG MAR15-010 & GB ) ( paratypes ), LIP 0001410 (& GG MAR15-013 & GB ) ( paratypes ), 11 June 2015 , Le Prêcheur , integral reserve Prêcheur Grand-Rivière , path to the cascade of the Couleuvre river , on Bambusa vulgaris clusters, leg . & det . G . Gruhn ; GG MAR15-186 , 23 June 2015 , Sainte-Luce , forest of Montravail , Grand-Fleur , on undefined hardwood, leg . & det . G . Gruhn ; FRENCH GUIANA : GG GUY13-080 , 22 October 2013 , Saül , Crique Limonade , “D” Diadema track, on bark, leg . & det . G . Gruhn ; two collections, collected same place and same day, GG GUY13-118 and GUY13- 120 (& GB ), 23 October 2013 , Saül , Crique Limonade , “ A ” Diadema track, slop zone, on bark, leg . & det . G . Gruhn . FIGURE 6. S. aculeocrepitans . Basidiomes, fresh material in situ . A: holotype. B: GG MAR15-008. C: GG MAR15-010. Other specimens examined for this article: — Ceriporiopsis carnegieae : USA : PRM JV 1209/45, 4 Sep. 2012 , Tucson, Saguaro National Park, on dead saguaro stem lying on the ground, leg . & det . J. Vlasák, KX081184. Sistotremastrum guttuliferum : PORTUGAL : typus MA-fungi 82105, 16566-Tell, Madeire Island, Santana, Levada da Fajã, on wood. Sistotremastrum lateclavigerum : FRANCE : LY 13467, 17 June 1988 , Tartas, Landes, on Pinus pinaster , leg . G. Gilles. Sistotremastrum niveocremeum : FRANCE : GG 111023-475, 27 October 2010 , Terrou, Lot, Bave valley, on deciduous tree, leg . & det . G. Gruhn; GG 140911-303, 11 September 2014 , Autrans, Isère, meadow of Gève, on dead wood of Abies alba on the ground, leg . & det . E. Martini; LY 2051, 10 October 1955 , Couzon-au-Montd’Or, Rhône, on the road between the Virgin and the access to the Mont d’Or, on Acer campestre , leg. & det . J. Boidin; LY 4580, 24 Nov. 1963 , les Echets, Ain, on little woody piece, probably Genista , leg. & det . J. Boidin; LY 13632, 23 Jan. 1989 , Tartas, Landes, on Phyllostachys cf. mitis , leg . G. Gilles, det . J. Boidin. Sistotremastrum suecicum : FRANCE : two collections GG 131105-356 and GG 131105-357, 5 November 2013 , Marseille, Bouches-du-Rhône, Forêt Domaniale des Calanques, vallon de la Fenestre, on dead wood of Pinus halepensis dead due to forest fire, leg . & det . G. Gruhn, conf. B. Duhem; LY 12084, 27 Sept. 1986 , Uhart-Mixe, Haute-Savoie, on very decayed Carpinus wood, leg . G. Gilles, det . J. Boidin; LY 13794, 16 July 1989 , Tartas, Landes, on decayed Pinus beam, leg. & det . G. Gilles.