Hygrocybe pellucida K. P. D. Latha & P. Haridev

Deepna Latha, K. P., Haridev, P., Anil Raj, K. N. & Manimohan, Patinjareveettil, 2024, Hygrocybe pellucida-a new species of Hygrophoraceae from Kerala State, India, Phytotaxa 646 (3), pp. 282-292 : 288-290

Hygrocybe pellucida K. P. D. Latha & P. Haridev sp. nov. Figs. 3–4

MycoBank no.: MB 851431

Diagnosis:— Characterized by small, viscid, translucent basidiocarps, a whitish to grayish pileus with reddish pellucid striations, dimorphic basidiospores and basidia, a sterile lamella edge with abundant pseudocystidia, an ixotrichoderm-type pileipellis and an ixocutis-type stipitipellis. Differs from H. snigdha in having a grayish red, broadly applanate pileus with a small central depression, adnexed lamellae with a crenulate edge, an ixotrichoderm-type pileipellis and distinct nrITS and nrLSU sequences.

Type:— INDIA. Kerala State: Malappuram District, Mayilanji Valavu , 11°07.958′N, 075°52.479′E, 24 June 2023, P. Haridev DKP-SERB131 ( CALI!). GenBank accessions nrITS: OR982363 ; nrLSU: OR982364 .

Etymology:— pellucida (Latin) , translucent; refers to the translucent basidiocarps of this species.

Description:—Basidiocarps small, viscid, translucent. Pileus 4–15 mm diam., hemispherical or campanulate when young, becoming applanate or broadly applanate with a small central depression at maturity; surface initially whitish at the center, vivid red (11A8/OAC497) elsewhere, becoming orange-gray (6B2/OAC669) on and around the center, grayish red or deep red (8B6/11A6/OAC626/OAC497) on the striations, pinkish white (9A2/OAC578) elsewhere with an orange-gray margin (6B2/OAC669) at maturity, not hygrophanous, strongly viscid, translucent-striate towards the margin; margin inflexed when young, straight to somewhat reflexed at maturity, wavy. Lamellae adnexed to narrowly adnate or sinuate, subdistant, with lamellulae in 1–2 tiers, grayish red or deep red (8B6/11A6/OAC626/OAC497), up to 1.5 mm wide; edge crenulate, mostly concolorous with the sides or at times one or two lamellae with a reddish brown (8D6/OAC642) edge. Stipe 2–26 × 1–2.5 mm, central, terete, equal, solid, cartilaginous; surface brownish orange (6C4/OAC633) all over when young, becoming pale red (11A3/OAC501) towards the apex, orange-gray (5B2/ OAC683) elsewhere at maturity, translucent, subviscid, finely pruinose all over; base slightly swollen. Context soft, up to 1 mm wide, white. Odor and taste not distinctive.

Basidiospores dimorphic; macrospores 8–10(11) × 6–8 (9 ± 1.4 × 6.4 ± 1.7) µm, Q = 1–2, Qm = 1.4, broadly ellipsoid or ovoid, thin-walled, hyaline, with oleaginous contents, inamyloid; microspores 3–5 × 3–4 (4.3 ± 1.3 × 3.8 ± 1.2) µm, Q = 1–1.3, Qm = 1.1, globose or subglobose, thin-walled, hyaline, with oleaginous contents, inamyloid. Basidia dimorphic; macrobasidia 36–46 × 12–15 µm, clavate or broadly clavate, thin-walled, hyaline or with some oleaginous contents, inamyloid, 2- or 4-spored; sterigmata up to 4 µm long; microbasidia 22–30 × 6–12 µm, narrowly clavate or clavate, thin-walled, hyaline or with some oleaginous contents, inamyloid, 1-, 2- or 4-spored; sterigmata up to 4 µm long. Pleurocystidia absent. Lamella edge sterile with pseudocystidia originating from the tramal hyphae. Pseudocystidia 15–60 × 3–9 µm, abundant, narrowly clavate, narrowly cylindrical or flexuose, mostly septate, rarely with bifurcations, thin-walled, hyaline or with oleaginous contents, inamyloid. Lamella trama slightly subregular to almost regular, made up of inflated (up to 24 µm wide), very long (> 500 µm) elements occasionally with tapering ends at the center, and narrow (3–5 µm wide), rather closely septate hyphae towards the hymenium and lamella edge, thinto slightly thick-walled, hyaline, inamyloid. Pileus trama subregular; hyphae 5–15 µm wide, thin- to slightly thick-walled, hyaline or with a pale yellowish plasmatic pigment, inamyloid. Pileipellis an ixotrichoderm; terminal cells 24–59 × 2–4 µm, narrowly cylindrical, seldom flexuose, thin-walled, hyaline or with oleaginous contents, inamyloid. Stipitipellis an ixocutis composed of up to 10 layers (up to 60 µm wide) of narrow, parallel hyphae, 3–8 µm wide, thin-walled, hyaline or with oleaginous contents, inamyloid. Clamp connections observed on all hyphae.

Habit and Habitat:— Solitary or in small groups on soil among decaying grass.

Geographical distribution range:— Known only from the type locality in Kerala State, India.

Additional specimens examined:— INDIA. Kerala State: Malappuram District, Mayilanji Valavu , 11°07.958′N, 075°52.479′E, 11 August 2018, K. P. Deepna Latha and K. N. Anil Raj DKP530 ; 11 September 2022, K. P. Deepna Latha and K. N. Anil Raj DKP547; 12 September 2022, P. Haridev DKP-SERB88 ( CALI) .

Figures

FIGURE 3. Hygrocybe pellucida. A–F. Basidiocarps. G. Macrospores. H. Microspores. I. Microbasidium. J. Macrobasidium. K. Pseudocystidia. L. Pileipellis. M. Stipitipellis. Scale bars: A–F = 10 mm; G–K = 10 µm; L = 25 µm; M = 100 µm. Photos by: K. P. Deepna Latha & P. Haridev.

FIGURE 4. Hygrocybe pellucida. A. Macrospores. B. Microspores. C. Macrobasidia. D. Microbasidia. E. Pseudocystidia. F. Stipitipellis. G. Pileipellis. Scale bars: A–E = 10 mm; G = 20 µm; F = 50 µm. Drawings by: P. Haridev.