Entoloma luteodiscum K. N. A. Raj & Manim., 2016

Anil Raj, K. N. & Manimohan, Patinjareveettil, 2016, Three new species of Entoloma subgenus Nolanea from India based on morphology and molecular phylogeny, Phytotaxa 286 (4), pp. 232-244 : 235-236

Entoloma luteodiscum K. N. A. Raj & Manim. , sp. nov. Figs. 2A–F

MycoBank MB 818067

Etymology:—The specific epithet refers to the yellowish pileus of this species.

Diagnosis:—This species is characterized by small, collybioid basidiocarps; a pale brownish yellow, centrally depressed pileus; adnate to sinuate and occasionally furcate lamellae; 5–6(–7)-angled basidiospores 7–8 × 6–7.5 μm; a fertile lamella-edge; a hymenium lacking cystidia; a cutis-type pileipellis and stipitipellis, and a distinct ITS sequence (KX774267).

Holotype:— INDIA. Kerala State: Kozhikode District, Poyilkavu Sacred Grove : 24 September 2009, K. N. Anil Raj AR77 ( CAL 1312 ).

Description:— Basidiocarps small, collybioid. Pileus 7–15 mm diam., convex to somewhat plano-convex with a depressed center; surface pale brownish yellow (5C5, 5C6/OAC805) at the center, pale yellow (4A2, 4A3/OAC815) towards the margin, hygrophanous and becoming paler, finely pellucid-striate, glabrous to the naked eye, finely appressed-fibrillose all over under a lens; margin incurved, crenate or somewhat wavy. Lamellae adnate to sinuate, occasionally furcate, subclose, orange-white (5A2/OAC759), up to 2 mm wide, with lamellulae in 2–3 tiers; edge crenate or slightly wavy, concolorous with the sides. Stipe 10–22 × 1.5–4 mm, central or slightly eccentric, terete or compressed, equal or slightly tapering towards the apex, cartilaginous, hollow; surface pale orange (5A3/OAC758) or grayish orange (5B4, 5B4/OAC717), smooth, glabrous; base with a white mycelial mass. Odor and taste not distinctive.

Basidiospores 7–8 × 6–7.5 (7.5±0.49× 6.4±0.49) μm, Q = 1.0–1.3, Qm = 1.17, mostly 5- to 6-angled, rarely 7-angled in profile, mostly sub-isodiametric, rarely isodiametric or heterodiametric, hyaline, thin- to slightly thick-walled. Basidia 24–33 × 8–10 μm, clavate, hyaline or pale yellow, thin-walled, 4-spored or rarely 2-spored; sterigmata up to 5 μm long. Lamella-edge fertile. Pleurocystidia and cheilocystidia absent. Lamellar trama subregular; hyphae 4–23 μm wide, pale golden yellow, thin-walled. Subhymenium inconspicuous. Pileitrama interwoven; hyphae 6–19 μm wide, pale yellow, thin-walled. Pileipellis a cutis, rarely disrupted by erect hyphae; hyphae 5–17 μm wide, with a pale yellow intraparietal pigment, thin-walled. Stipitipellis a cutis, occasionally disrupted; hyphae 4–10 μm wide, pale yellow or pale brownish yellow, thin-walled. Caulocystidia absent. Brilliant granules present in lamellar trama. Clamp-connections not observed on any hyphae.

Habitat: — scattered on the ground among leaf litter or often attached to twigs under broadleaf trees.

Geographical distribution range:—known only from two localities in Kozhikode and Kollam Districts of Kerala State, India.

Additional specimens examined:— INDIA. Kerala State: Kollam District, Thenmala Forest, 03 November 2015, K. N. Anil Raj, AR1010 (CAL1386).

Comments:—Characters such as the small, collybioid basidiocarps, the presence of intraparietal pigments on the hyphae of pileipellis and upper pileitrama, the absence of encrustations and plasmatic pigments in any hyphae and the isodiametric to heterodiametric basidiospores place this species in section Endochromonema of subgenus Nolanea .

Entoloma obscurum Dennis (1953: 196) , a species from Trinidad ( Pegler 1983), resembles E. luteodiscum in having a somewhat similar - shaped pileus, similarly attached, rarely furcate lamellae with somewhat similar color, a hollow stipe with a similar surface and a white basal mycelium, basidiospores of rather similar size (7–8.5 × 5.5–7.5 μm) and shape, absence of cystidia and clampless hyphae. However, E. obscurum differs from E. luteodiscum in having larger basidiocarps with a grayish brown, silky shining, non-striate pileus, subdistant lamellae, and a repent epicutis-type pileipellis with a pale grayish vacuolar pigment. Nolanea mazophora ( Berkeley & Broome 1871: 537) Pegler (1977a: 200) , a common species in the tropics, seems to be close to E. luteodiscum in having a somewhat similar-colored, striate pileus, somewhat similarly attached lamellae, basidiospores of somewhat similar size (7–9 × 6–7 μm) and shape, absence of pleurocystidia, a fertile lamella-edge and clampless hyphae. Nolanea mazophora , however, is distinguished from E. luteodiscum in having larger basidiocarps with an umbonate pileus, moderately crowded lamellae, a fibrillose-striate stipe, absence of 2-spored basidia, and pileipellis hyphae with a yellowish brown vacuolar pigment. A BLASTn search in the GenBank database using the ITS sequences (648 bp & 650 bp) obtained from the present species showed Entoloma species B 356 (FN669198), an undescribed species from Estonia, followed by E. conicosericeum (JX454883) as the closest hits with 93% sequence identities. Entoloma conicosericeum Vila, F. Caball. & Eyssart. in Vila et al. (2013: 21), a species reported from Spain ( Vila et al. 2013), is somewhat similar to the present species in having basidiospores of somewhat similar size and shape (7.6–9.5(10.1) × 6.3–8.2 μm), a lamella-edge devoid of cheilocystidia and a cutis-type pileipellis. However, E. conicosericeum has larger basidiocarps, an umbonate, blackish brown pileus with a non-striate, radially fibrillose, and velutinous surface, emarginate to free lamellae, and pileipellis hyphae with encrustations and clamp-connections.

Figures

FIGURE 2. A–F: Entoloma luteodiscum (CAL 1312, holotype). A–C. Basidiomata; D. Basidiospores; E. Basidium; F. Pileipellis. Scale bars: A–C = 10 mm; D–F = 10 μm. Photos by K. N. Anil Raj.