Lactifluus russulisporus Dierickx & De Crop

Dierickx, Glen, Froyen, Marie, Halling, Roy, Wisitrassameewong, Komsit, Lynn Delgat,, Crop, Eske De & Verbeken, Annemieke, 2019, Updated taxonomy of Lactifluus section Luteoli: L. russulisporus from Australia and L. caliendrifer from Thailand, MycoKeys 56, pp. 13-32 : 16-18

Lactifluus russulisporus Dierickx & De Crop Figs 1 , 3 , 4

Original diagnosis.

Basidiocarps small (up to 4 cm cap diam.). Cap and stipe dry, matt, yellowish white to pale brown. Context with unpleasant, fishy smell. Latex copious, watery white, staining tissues brown. Basidiospores broadly ellipsoid 7.0- 7.8-7.9 -8.7 × 5.7- 6.4-6.5 -7 μm (n=40, Q = 1.14- 1.23 -1.40); ornamented with irregular and isolated warts which are up to 1.3 μm high. True pleurocystidia absent, but with few to abundant sterile elements in the hymenium. Pileipellis a lampropalisade. L. russulisporus differs from its sister species, L. caliendrifer , by its longer basidia, slightly bigger spores with a somewhat heavier and more irregular ornamentation and the absence of abundant thick-walled marginal cells.

Basidiomes rather small. Pileus 20-40 mm diam., convex to plano-convex and depressed on disc to uplifted and slightly depressed, yellowish white (4A2) to pale brown, dry, matted, subtomentose to finely subvelutinous and somewhat subrugulose to subcorrugate; margin inrolled. Stipe 10-30 × 5-10 mm cylindrical, dry, matt, yellowish white, sometimes paler brownish towards the base, with white mycelium at the base. Lamellae adnexed to subdecurrent, rather close, pale greyish white to yellowish white, turning darker to near pale brown with age. Context white, solid to somewhat pithy in the stipe; smell unpleasant, fishy; taste mild. Latex copious, watery white, staining tissues brown.

Basidiospores broadly ellipsoid 7.0- 7.8-7, 9 -8.7 × 5.7- 6.4-6, 5 -7 µm (n=40, Q = 1.14- 1.23 -1.40); ornamentation amyloid, prominent, composed of irregular and isolated warts which are up to 1.3 µm high, never forming a reticulum; plage distinct and inamyloid. Basidia 43-71 × 8-14 µm, subcylindrical to subclavate, thin-walled, mostly 4-spored. Pleurolamprocystidia absent. Sterile elements inconspicuous to abundant, cylindrical, sometimes a bit irregular, 17-64 × 3-7 µm, thin-walled and up to 3-septate, sometimes emerging, with terminal cells 9-39 × 2.5-6.5 µm. Pleuropseudocystidia generally abundant, sometimes emerging, 3-8 µm diam., irregularly cylindrical; apex obtuse to subcapitate; content oil-like to granular. Lamellae edge sterile, marginal cells 23-74 × 2-7.5 µm, thin-walled, cylindrical to subfusiform or slightly subclavate, often branched, not septate or with up to 3 septae, with terminal cells 7-49 × 2-7.5; apex obtuse to subcapitate; some marginal cells may be slightly thick-walled, but these are scarce. Hymenophoral trama cellular, with lactifers. Pileipellis a lampropalisade; elements of the suprapellis 35-180 × 2.5-6 µm, cylindrical, thick-walled and often septate; apex obtuse to capitate; subpellis cellular, composed of isodiametric, sometimes slightly thick-walled cells, which are 7-30 µm diam. Stipitipellis a trichoderm to lamprotrichoderm; ascending hyphae 35-80 × 4-6 µm, up to 3 septate, slightly thick-walled to thick-walled especially basal cells, apex obtuse to capitate. Clamp connections absent.

Distribution.

Known from Eastern Australia.

Ecology.

East-Australian wet sclerophyll and subtropical rainforest, scattered to gregarious on soil under Leptospermum , Syncarpia , and Eucalyptus spp.

Etymology.

Named after the spores which are reminiscent of the spore ornamentation and shape of many Russula species.

Conservation status.

Unknown.

Specimens examined.

Australia. Queensland West of Brisbane, D’Aguilar National Park, Maiala Area walking tracks, alt. 680 m, 27°20'0.3"S, 152°45'48.3"E, rain forest, scattered on the soil near Eucalyptus sp. and Lophostemon sp., 8 March 2012, R. E. Halling and N. Fechner, R.E.H. 9674 (BRI, NY); Queensland: Fraser Island, Wanggoolba Creek Road, West of Central Station, alt. 90m, 25°28'S, 153°2'E, gregarious on sand with Leptospermum , Syncarpia , Eucalyptus pilularis and Eucalyptus microcorys , 27 May 2010, leg.: R. E. Halling, N. Fechner and M. Castellano, R.E.H. 9398 (holotypus BRI, isotypus NY).

Remarks.

Lactifluus russulisporus differs from its sister species, L. caliendrifer , by its longer basidia, slightly bigger spores with a somewhat heavier and more irregular ornamentation and the absence of abundant thick-walled marginal cells.

Figures

Figure 1. A-B Lactifluus russulisporus basidiomes C-D L. caliendrifer basidiomes A holotype, RH 9398 B RH 9674 C holotype, KW 378 D KW 392.

Figure 3. A-D Microscopic characters of Lactifluus russulisporus A marginal cells, RH 9764 B marginal cells, holotype, RH 9398 C basidiole and sterile elements, holotype, RH 9398 D spores, holotype, RH 9398. Scale bar: 10 µm.

Figure 4. Microscopic features of Lactifluus russulisporus A section through the pileipellis B pileipellis hairs C pseudocystidia D basidia E marginal cells F sterile elements from the hymenium G basidiospores. Illustrations by G. Dierickx and A. Verbeken. Scale bars: 10 µm.