Lactifluus umbonatus K. P. D. Latha & Manim., 2016

Deepna Latha, K. P., Anil Raj, K. N., Farook, V. Adnaan, Sharafudheen, Shahina A., Parambil, Neeraja K. & Manimohan, Patinjareveettil, 2016, Three new species of Russulaceae from India based on morphology and molecular phylogeny, Phytotaxa 246 (1), pp. 61-77 : 65-68

Lactifluus umbonatus K. P. D. Latha & Manim. , sp. nov. Figs. 1A–B ; Figs. 2A–K ; Fig. 5A

MycoBank MB 815041

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

Diagnosis:— Lactifluus umbonatus has smaller basidiomata with an acutely umbonate pileus, anastomosing, grayish orange lamellae, milky-white latex and a fishy smell. Microscopically this species has smaller basidiospores and a hymenium with both pleuro- and cheilocystidia.

Holotype:— INDIA. Kerala State: Wayanad District, Pulpally, Kuruva Islets on River Kabani , 27 September 2013, K. P. Deepna Latha, DKP238 ( CAL 1241 ).

Description:— Basidiomata small. Pileus 3–11 mm diam., conico-convex with an acute umbo when very young, becoming convex to plano-convex still with an acute umbo, at times with a slight depression around the umbo; surface initially brown (6E4/OAC635) at the center, orange gray (5B2/OAC675) elsewhere, becoming dark grayish brown (7F3/OAC637) at the center and dark brown (7F5, 7F6/OAC637) elsewhere at maturity, dry, faintly wrinkled as well as finely tomentose all over; margin initially incurved, becoming slightly decurved at maturity, crenate or somewhat wavy, finely fissured. Lamellae subdecurrent, anastomosing, ventricose, up to 3 mm wide, subdistant, with lamellulae of 3–5 lengths, grayish orange (6B3/OAC634); edge entire or slightly wavy, dark brown (6F6/OAC635). Stipe 7–19 × 1–2.5 mm, central, terete or slightly compressed, equal or tapering towards the apex, rather flexuous, fistulose; surface orange gray (5B3/0AC659) all over when young, becoming dark brown (6F6/OAC635) all over at maturity, finely tomentose all over, densely so towards the base; base slightly enlarged, with abundant, whitish basal mycelium. Latex milky-white, unchanging. Context up to 1.5 mm thick, soft. Odor strong, fishy. Taste not distinctive.

Basidiospores 6–8 × 6–8 (6.67 ± 0.69 × 6.45 ± 0.6) μm, Q = 1–1.66, Qm = 1.03, subglobose to globose with a prominent hilar appendix, with an amyloid ornamentation composed of partially continuous, interconnected ridges up to 0.5 μm high forming an incomplete reticulum. Basidia 35–45 × 8–10.5 μm, clavate, thin-walled, 4-spored; sterigmata up to 5 μm long. Lamella edge sterile with copious marginal cells often intermixed with scattered cheilocystidia. Marginal cells 24–53 × 4–7 μm, cylindrico-clavate or flexuoso-cylindric, often septate, branched, thin- to slightly thick-walled, with a dense, brown intracellular pigment. Cheilocystidia 29–43 × 4.5–6 μm, scarce, sinuoso-cylindric, thin-walled, hyaline, with refractive, needle-like contents. Pleurocystidia scattered, 55–78 × 7–10 μm, flexuoso-cylindric or subfusoid often with a tapering apex, thin-walled, hyaline, with refractive, needle-like, oleaginous contents, often intermixed with structures similar in morphology to marginal cells (17–30 × 4–6 μm), but lacking brown intracellular pigment, hyaline, thin- to slightly thick-walled. Lamellar trama subregular with a few lactifers; hyphae 2–11 μm wide, thin-walled, with pale yellow or yellowish brown intracellular contents in the central hyphae, inamyloid. Pileus trama composed of both hyphae and sphaerocytes; hyphae 2–3 μm wide, with pale brown contents, thin-walled, inamyloid; sphaerocytes 16–37 × 13–20 μm, abundant, thin-walled, hyaline. Pileipellis a 28–41 μm thick palisade with scarce pileocystidia; elements of palisade 28–36 × 6–10 μm, versiform; clavate, clavate with a pedicel, fusiform, flexuous, flexuoso-cylindric and sphaero-pedunculate, with reddish brown intracellular contents, slightly thick-walled; elements of subpellis composed of rather subglobose or more or less pseudoparenchymatous cells (12–18 × 8–16 μm), thin-walled, with reddish brown intracellular contents. Pileocystidia 34–54 × 6–7 μm, sinuoso-cylindric or flexuous, thin-walled, hyaline, with refractive, needle-like contents. Stipitipellis a 27–50 μm thick palisade at the apex and the middle, gradually becoming a trichoderm toward the base, occasionally intermixed with caulocystidia towards the apex; elements of palisade 13.5–45.5 × 5.5–9 μm, similar in morphology to pileipellis elements, hyaline, with reddish brown intracellular contents, slightly thick-walled; trichoderm made up of often vertical, fusoid hyphae with cystidioid terminal elements; hyphae 2–5 μm wide, with a pale yellow wall pigment and dark brown intracellular contents, thinto slightly thick-walled; terminal elements cystidioid, 31–60 × 6–8 μm, cylindrical, flexuous or subfusoid, hyaline, thin- to slightly thick-walled. Caulocystidia 28.5–46 × 5.5–7 μm, scarce, flexuoso-cylindric or subfusoid, thin-walled, hyaline, often with refractive, needle-like, oleaginous contents. Clamp connections absent.

Habitat:—in small groups, on sandy soil, near Hopea ponga ( Dipterocarpaceae ) trees.

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

Comments:— Lactifluus umbonatus clearly fits into Lf. subg. Gerardii because of its brown-colored pileus and stipe, subdistant lamellae, pseudoparenchymatous subpellis, reticulately ornamented basidiospores with interconnected warts and occasional pleuro- and cheilocystidia ( Stubbe et al. 2010; Stubbe et al. 2012a; Montoya et al. 2012). Lactifluus bicolor ( Massee 1914: 73) Verbeken (in Stubbe et al. 2012b: 484), a Malaysian species ( Le et al. 2007; Stubbe et al. 2012a; Montoya et al. 2012), seems to be somewhat close to the present species in having dark brown pileus and stipe, subdecurrent, distant lamellae with a colored-edge, globose to subglobose basidiospores and a palisade-type pileipellis. However, Lf. bicolor differs from the present species in having larger basidiomata, slightly larger basidiospores (7.5– 8.0–8.4–8.8 (9.6) × 6.4–7.1–7.8–8.4 (8.6) μm), lamellae devoid of pleurocystidia, the presence of cheiloleptocystidia, differently-shaped terminal elements of pileipellis and a watery latex. Lactifluus parvigerardii X.H. Wang & D. Stubbe (in Wang et al. 2012: 185), a species from China ( Wang et al. 2012), is similar to Lf. umbonatus in having similarsized basidiomata, decurrent lamellae, a brownish stipe with a white tomentose base, basidiospores with an incomplete reticulum, presence of pleurocystidia, occurrence of lactifers in the lamellar trama and a palisade-type pileipellis. However, Lf. parvigerardii is distinguished from Lf. umbonatus in having an infundibuliform, yellowish brown pileus with a rugulose surface, pale yellow lamellae, subglobose to ellipsoid and slightly larger basidiospores ((6.0) 7–8.5 (9.0) × 5.5–7.0 μm), absence of cheilo-, pileo- and caulocystidia and a trichopalisade-type stipitipellis.

Lactarius crenulatus K. Das & Verbeken (2012: 38) , a species recently reported from India ( Das & Verbeken 2012) seems to be somewhat close to Lf. umbonatus in having an almost similar shape and color of the pileus, subdecurrent lamellae with a colored-edge, a stipe which is slightly wider towards the base, globose to subglobose, amyloid basidiospores, a sterile lamella edge, the presence of marginal cells with brown intracellular pigment, the presence of lactifers in lamellar trama, pileipellis elements with brown intracellular pigment. Lactarius crenulatus , however, has larger basidiomata with a depressed pileus center, broadly adnate (at younger stages), pale yellow lamellae, a snuff brown, solid stipe, a watery latex, slightly larger basidiospores (7.2–7.9–8.7 × 7.0–7.5–8.3 μm) with a distinct plage and ridges forming a complete reticulum, a hymenium devoid of pleuro- and cheilocystidia, a hymeniderm- to a trichoderm-type pileipellis and abundant pleuropseudocystidia. Lactarius fuscomarginatus Montoya, Bandala & Haug (in Montoya et al. 2012: 176), a Mexican species ( Montoya et al. 2012), shares a few features with Lf. umbonatus in having similar-colored pileus and stipe, distant and comparable width of lamellae with a brown edge, a stipe with a whitish mycelium, white latex, comparable shape of basidiospores and the presence of sphaerocytes and lactifers in the lamellar trama. Lactarius fuscomarginatus , however, is distinguished from Lf. umbonatus in having larger basidiomata with an infundibuliform pileus, cream-colored, decurrent, furcate lamellae lacking anastomoses, velvety, striate stipe which is tapered towards the base, larger basidiospores (8–)9–11 × (7–)8–10.5(–11) μm, the presence of both 2- and 4-spored basidia, the absence of pleuro- and pileocystidia, the presence of cheiloleptocystidia and a hymenoepithelium to a trichoepithelium-type pileipellis.

No close hits were obtained with a zero e-value in a BLASTn search using the ITS sequence of Lf. umbonatus (CAL 1241: 652 bp).

Figures

FIGURE 1. A–F: Basidiomata of the three new species. A–B. Lactifluus umbonatus. C–D. Lf. indicus. E–F. Lactarius keralensis. Scale bars: A, C–F = 10 mm; B = 5 mm. Photos: A–B. By K.P.D. Latha; C–D. By K.N.A. Raj; E–F. By V.A. Farook.

FIGURE 2. A–K: Lactifluus umbonatus (CAL 1241, holotype). A. Basidiomata; B. Basidiospores; C. Basidium; D. Pleurocystidia; E. Cheilocystidia; F. Pileocystidium; G. Caulocystidium; H. Marginal cells; I. Sterile cells seen on sides of lamellae; J. Pileipellis; K. Stipitipellis. Scale bars: A = 5 mm; B = 5 μm; C–K = 10 μm.

FIGURE 5. A–C: SEM images of basidiospores of the three new species: A. Lactifluus umbonatus (CAL 1241, holotype). B. Lactifluus indicus (CAL 1282, holotype). C. Lactarius keralensis (CAL 1281, holotype). Scale bars: A–B = 5 μm; C = 2 μm.