Coprotus epithecioides Matocec & I. Kusan

Kusan, Ivana, Matocec, Neven, Jadan, Margita, Tkalcec, Zdenko & Mesic, Armin, 2018, An overview of the genus Coprotus (Pezizales, Ascomycota) with notes on the type species and description of C. epithecioides sp. nov., MycoKeys 29, pp. 15-47 : 22-30

Coprotus epithecioides Matocec & I. Kusan sp. nov. Figs 4, 5

Type.

CROATIA. Lika-Senj County, Sjeverni Velebit National Park, northern part of the Mt. Velebit, Hajdučki kukovi area, 150 m W from Golubić peak (1650 m), 44°46.05'N; 15°00.88'E, 1580 m a.s.l.; on dung of chamois ( Rupicapra rupicapra ), 11 Oct 2017, I. Kušan (holotype CNF 2/10450, GenBank sequences ITS MG593539, LSU MG593540).

Etymology.

The specific epithet refers to epithecium-like ascal protective formation composed of swollen apical paraphyses cells.

Description.

Apothecia not confluent regularly circular to irregular from the top view, at first oblate, then turbinate, finally pulvinate from the side view, sessile, subhyaline to creamy grey or pale yellowish, glabrous, *170-420 µm in diameter, solitary or gregarious. Hymenium only very finely scurfy, ascal protrusions not clearly visible. Margin rounded in vertical median section, entire and smooth, expanded with downwards positioned rim, never raised above hymenial plane. Outer surface smooth, concolorous with the hymenium. Subicular hyphae indistinguishable. Hymenium *75-98 µm thick. Asci shortly cylindric with slightly truncate apex, *60-74.8 × 13.4-15.5 µm, †51.5-62 × 11.8-14 µm (Q = 3.8-5.2), when mature *protruding above hymenium up to 7.5 µm, pars sporifera*28-34 µm, 8-spored, hyaline; base attenuated, bifurcate, arising from perforated crosiers; only optimally oriented fully mature asci with flat lentiform operculum clearly delimited prior the spore discharge, *6.3-6.6 µm in diam. and *0.5 µm thick, lateral wall 3-layered, *0.6 µm thick, after spore discharge operculum as a rule clearly visible; in IKI inamyloid; in CR outermost wall vividly rutile-red throughout the ascal length, median layer pale rutile-yellow, innermost layer greyish; in CB asci cyanophobic. Ascospores *7.9 –8.8– 9.6 × 4.8 –5.2– 5.6 µm, †8 –9.1– 9.5 × 4.2 –5– 5.2 µm, *Q = 1.5 –1.6– 1.9, †Q = 1.6 –1.9– 2.0, bilaterally symmetrical with one side flattened, subphaseoliform to phaseoliform, poles rounded, 1-celled; uni- to biseriate in living asci, freshly ejected remain in a group for a while due to the delicate subglobose sticky sheath enveloping individual spores; hyaline, smooth; wall 3-layered, 0.4 µm thick, perispore dull, epispore brightly refractive, endospore subhyaline, barely optically differentiated; eguttulate, uninucleate, nucleus always ± polarly positioned, 2.2-2.5 µm wide; in IKI perispore and epispore not stained, endospore purplish, nucleus slightly contrasted; in CRB without differential stainings, the edges of spore sheath sharply contrasted, after applying KOH spore sheath instantly dissolves, perispore not loosening, endospore layer purplish-rosaceous; in CB with one eccentrically positioned de Bary bubble in mature spores, perispore not loosening, moderately cyanophilic. Paraphyses ± densely septate, with thin, hyaline walls, cylindric in the lower part, often branched in the upper part, rarely simple, apically ± bent clavate or capitate, not producing copious exudate; of two types: (a) epithecioid, reaching higher level, with apical short and capitate cell, *6.8-10 × 5-9.9 µm, †6.2-11.2 × 4-8 µm, with 1-2 subapical cells often also swollen (moniliform), forming ± continuous layer above living immature asci, and (b) of usual type with elongated clavate apical cells, *8.2-14.8 × 2.3-4.4 µm, †5.5-11 × 2-3.3 µm; both types may contain yellow-orange pigment, often of crystalloid, fibrillar structure; pigment in IKI cinnamon-grey, in CRB purplish-lilac, often barely visible since mainly included in large globose, deeply stained blue-violet vacuole; in CB wall cyanophobic, cytoplasm pale greyish-blue. Margin reduced, composed of textura globulosa-angularis, cells not elongated, *3.8-6 µm wide, cylindric-elongated cells absent; weakly cyanophilic in CB. Subhymenium hyaline, not differentiated from medullary excipulum. Medullary excipulum hyaline, in the central part *32-56 µm thick, in the middle flank *10-14 µm thick, composed of textura epidermoidea, cells thin-walled, *2.3-4.8 µm wide, in CB cyanophobic. Ectal excipulum hyaline, in the middle flank *17-22 µm thick, composed of textura globulosa-angularis, cells *9.8-16.5 × 7.8-14.7 µm, †4.5-12 × 2.3-9.5 µm, walls thickened, refractive, yellowish, *0.5-0.7 µm thick, in CB cell walls slightly cyanophilic. Overall excipulum without crystalline matter, dextrinoid reaction in MLZ and colouring in KOH; in IKI inamyloid and devoid of glycogene accumulations. Anamorph not found.

Distribution and ecology.

The species is known so far only from Mt. Velebit, Croatia. The only collection originates from chamois dung in the alpine karstic habitat.

Other specimens examined.

None.

Notes.

Coprotus epithecioides has several characters making it distinct from other species in the genus. The paraphyses are of two types, along with the usual filiform-clavate ones, there are also an abundance of those with very short, swollen apical cells, that mutually form an epithecioid protective layer over immature asci, a character not recorded so far in the genus Coprotus . Additionally, in the epithecioid type, 1-2 subapical cells are often also swollen. This gives the paraphyses a moniliform appearance. When present, paraphysal pigments are most often orange to reddish-orange and crystalloid, i.e. of fibrillar shape, resembling the carotenoid pigmentation of Scutellinia species. Spores are highly bilaterally symmetric compared to C. glaucellus , C. subcylindrosporus , C. argenteus and C. sexdecimsporus (which has only inconspicuously and partly bilaterally symmetric spores) and the spores are significantly shorter than those of C. subcylindrosporus , C. argenteus and C. sexdecimsporus . Coprotus glaucellus differs by the presence of only apically uninflated to subclavate paraphyses which do not form an epithecioid protective cover over immature asci. Also it has notably elongated cells at the marginal edge. As elaborated above, paraphysal cytoplasmic pigments normally also develop in this species if the fungus is strongly exposed to sunlight or artificial light with ultraviolet wave-lengths. The pigmentation is completely absent if the apothecia is grown continually under dark or low-light conditions (see notes under C. sexdecimsporus ).

Worldwide identification key to the putative species of the genus Coprotus