Candolleomyces niveosquamosus P.K. Nayana & C.K. Pradeep

Nayana, P. K. & Pradeep, C. K., 2024, Morphological and phylogenetic analyses reveal two new species of Candolleomyces (Psathyrellaceae) from India, Phytotaxa 659 (3), pp. 255-267 : 259-261

Candolleomyces niveosquamosus P.K. Nayana & C.K. Pradeep sp.nov. ( Figs. 2 , 3 )

MycoBank: MB854240

Diagnosis:—Differs from the closely related C. albosquamosus by slightly larger grayish brown pileus with dark brown disc (17.5–50 mm), larger (6.8–8.0 × 4.0–4.4 µm), brown basidiospores with a distinct germ pore and habitat.

Holotype:— INDIA. Kerala State: Thiruvananthapuram District . Palode, JNTBGRI campus, 8.75°N, 77.02°E, elev. 150 m, 07 April 2022, Nayana TBGT (M)18773!. GenBank: PP741631 ( ITS); PP741635 ( LSU).

Etymology:— niveosquamosus , refers to the white floccose velar squamules on the pileus.

Description:—Basidiomata small to medium sized, thin. Pileus 17.5–50 mm diam., convex, plano-convex, applanate to uplifted with a small obtuse umbo at centre; surface grayish orange (5B3), brownish gray (6C2) with a brown (6E4) to dark brown (6F5/6F6/7F5) disc, hygrophanous, with white evanescent floccose velar squamules dense at the centre, scattered towards the margin, pellucid striate, slightly wrinkled on drying, dry; margin straight, strongly appendiculate, incised. Lamellae adnexed, grayish brown (6D3), brown (6E4/7E4) to dark brown (6F4/6F56F7/7F7), up to 4 mm broad, close to crowded with lamellulae of 3–4 lengths; edge concolorous to the sides, fimbriate. Stipe 27–95 × 2–5 mm, central, cylindric, slightly tapering upward, curved, hollow, brittle; surface white, pruinose at the apex, covered with white fibrils or floccose velar squamules towards base; base with white strigose hairs. Context concolorous to the pileus, 1 mm broad, soft. Odor mild, not distinct. Spore print dark brown (8F4).

Basidiospores 6.8–8.0 × 4.0–4.4 µm (avL= 7.38 µm, avW= 4.06 µm), Q= 1.63–2.0 (Qm = 1.67), ellipsoid to elongate, light brown in water, grayish brown in 3% aqueous KOH, thick-walled, smooth, with a large germ pore and minute hilar appendix. Basidia 14.4–16.7 × 6.6–8.8 µm, clavate, 4-spored, thin-walled, hyaline. Lamella edge sterile with cheilocystidia and paracystidia. Cheilocystidia in groups or scattered, abundant, 24.9–34.1 × 10.1–16.8 µm, utriform, cylindrical, ellipsoid, rarely bifurcate, thin-walled, hyaline. Paracystidia moderately abundant, 13.2–21.6 × 11.6–19.4 µm, globose to subglobose, thin-walled, hyaline. Pleurocystidia absent. Hymenophoral trama regular, hyphae 2.5–16.7 µm wide, thin-walled, hyaline. Subhymenium pseudoparenchymatous. Pileal trama composed of thin-walled, hyaline, encrusted, inflated, 3.7–34.6 µm wide hyphae constricted at septa. Subcuticular hyphae brown in KOH. Pileipellis an epithelium, composed of globose to subglobose elements, 16.4–32.7 × 17.5–31.5 µm, thin-walled, hyaline. Veil made up of thin-walled, hyaline, branched, 6.6–18.9 µm wide hyphae. Stipitipellis a cutis, composed of thin-walled, hyaline, 3.70–29.81 µm broad, encrusted hyphae. Stipe apex with caulocystidia along with paracystidia. Caulocystidia moderately abundant, in groups or scattered, 23.7–55.1 × 11.3–13.7 µm, lageniform, utriform, cylindrical with obtuse or capitate apex, slightly thick-walled, hyaline. Paracystidia scattered, moderately abundant, 12.6–16.3 × 8.8–9.4 µm, globose to subglobose, thin-walled, and hyaline. Clamp connections common in all tissues.

Habit, Habitat and phenology:—Solitary, scattered to gregarious on sandy soil or on decayed angiosperm wood in tropical forest, Kerala State, India. This species fruits from March–May.

Additional specimens examined:— India, Kerala State: Thiruvananthapuram District, Palode , JNTBGRI campus: 22 April 2022, Nayana 18799 ; ibid., 19 May 2022, Nayana TBGT (M)18824 ; ibid., 30 March 2023, Nayana TBGT (M)19023 ; ibid., 11 April 2023, Nayana TBGT (M)19046 ; 25 April 2023, Nayana TBGT (M)19068 .

Notes:—Climatic geolocation, umbonate pileus with white evanescent floccose velar squamules, appendiculate pileal margin, brown ellipsoid to elongate basidiospores with a distinct germ pore, sterile lamella edge with abundant cylindrical to utriform cheilocystidia, moderately abundant cylindrical, lageniform to utriform caulocystidia, and small to medium-sized basidiomata are the characteristics of C. niveosquamosus .

A BLASTn search using the nrITS sequence generated from the present collections, TBGT(M)18773 (662 bp) and TBGT(M)19023 (631 bp), revealed a 98% sequence similarity with Candolleomyces cladii-marisci (Sicoli, N.G. Passal., De Giuseppe, Palermo, Pellegrino, D. Deschuyteneer & Voto) N.G. Passal. & Sicoli (2023:1) from Italy (MK080112). Candolleomyces cladii-marisci , initially described from Italy, is macroscopically similar to the Indian material; however, it is distinct in having a slightly smaller pileus (10–35 mm), larger basidiospores (7.2–11.8 × 4.3–6.0 µm) and slightly larger (21.5–54 × 6.0–11 µm) cheilocystidia.A pairwise comparison of the nrITS sequence of the new species with C. cladii-marisci showed 12 base pair differences. The new taxon is also related to other recently described species viz., C. albosquamosus P.K. Nayana & C.K. Pradeep and Candolleomyces thailandensis Suwannar., Kumla & Lumyong (2022: 431) . The smaller honey yellow to brownish gray pileus (12.0– 38.5 mm), smaller, pale basidiospores (6.0–6.4 × 3.6–4.0 µm) with an indistinct germ pore and lignicolous habitat are the distinguishing features of C. albosquamosus . A pairwise comparison of the nrITS sequences of C. albosquamosus with the new taxon exhibits 12 base pair differences. Candolleomyces thailandensis also shares a close morphological and molecular relationship with the present taxon, however, it differs in its smaller pileus (12–25 mm) and smaller (5.5–7.5 × 3.5–4.5 µm) basidiospores and molecularly by 24 base pair differences in the nrITS region.

Other morphologically and molecularly related species include C. yanshanensis C.L. Hou & Hao Zhou (2022: 114) , C. subcandolleanus C.L. Hou & Hao Zhou (2022: 115) , C. incanus C.L. Hou & Hao Zhou (2022: 117) , C. bivelatus (Contu) D. Wächt. & A. Melzer (2020: 1232) , C. candolleanus (Fr.) D. Wächt. & A. Melzer (2020: 1233) , C. trinitatensis (R.E.D. Baker & W.T. Dale) D. Wächt. & A. Melzer (2020: 1234) , C. badiophyllus (Romagn.) D. Wächt. & A. Melzer (2020: 1231) and C. badhyzensis (Kalamees) D. Wächt. & A. Melzer. (2020: 1231) . Candolleomyces yanshanensis , originally reported from China is distinct by its slightly larger pileus (20–60 mm) and larger basidiospores (5.8–8.2 × 3.3–5.4 µm). The Chinese species C. subcandolleanus and C. incanus are distinct by their smaller pileus (5.0– 20 mm; 5.0– 25 mm), and smaller basidiospores (5.5–6.7× 3.2–4.5 µm; 6.0–7.0 × 3.2–4.5 µm) lacking a germ pore ( Zhou et al. 2022). Larger basidiospores (9–9.5 × 5–5.5 µm), the presence of 2-spored basidia, and herbaceous habitat distinguish C. bivelatus from the present species ( Voto et al. 2019). Candolleomyces candolleanus can be distinguished by its slightly larger pileus (3–7 cm), and slightly larger basidiospores (7–9 × 4–5 µm) ( Smith 1972; Kits van Waveren 1985; Pegler 1986). Candolleomyces trinitatensis is distinct in its slightly smaller pileus (15–20 mm) and larger basidiospores (7–10 × 3.5– 5 µm) ( Baker & Dale 1951). Candolleomyces badiophyllus and C. badhyzensis can be distinguished by their notably larger (11–13.2 × 5.7–6.2 µm; 10.2–11.5 × 5.5–6.5 µm) basidiospores ( Kalamees 1981; Romagnesi 1952).

Figures

FIGURE 2. Candolleomyces niveosquamosus (TBGT(M)18773, holotype). A–D. Habit in situ; E, F. Basidiomata with immature to mature lamellae. Scale bars = 10 mm. Photos by: P.K. Nayana.

FIGURE 3. Candolleomyces niveosquamosus (TBGT(M)18773, holotype). A. Basidia; B. Basidiospores; C. Cheilocystidia; D. Caulocystidia; E. Pileipellis; F. Veil elements. Scale bars: A, B = 10 µm; C–F = 20 µm. Photos by: P.K. Nayana.