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Muséum National d'Histoire Naturelle, Laboratoire de Cryptogamie, 12 Rue Buffon, F-75005 Paris, France
Clark L. Ovrebo
Department of Biology, University of Central Oklahoma, Edmond, Oklahoma 73034
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSTAXONOMYDISCUSSIONLITERATURE CITED |
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Detailed illustrated descriptions are given for Russula panamae sp.nov, Russula aucarum, R. puiggarii and R. venezueliana, all of which are reported for the first time from Panamá. For Russula venezueliana and R. aucarum, it is also the first record since their original description. Taxonomy, systematic position, and related species are discussed for each species. Russula ochrostraminea is probably a synonym of R. venezueliana and section Delicoarchaeae is considered a possible synonym of subsection Lactarioideae or of section Metachromaticae.
Key words: biodiversity, Central America, Russulaceae, systematics
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSTAXONOMYDISCUSSIONLITERATURE CITED |
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). The island has a semideciduous lowland forest (Foster and Brokaw 1996) or, in the Holdridge classification (Holdridge 1967), is a tropical moist forest. Whereas BCI has been studied extensively with regard to many animal and plant groups, the larger macrofungi, especially those of the Agaricales, have not been documented. Along with the saprotrophic agarics that are common in lowland rainforests, species of presumed ectotrophic genera have also been collected on BCI. These genera include Russula, Lactarius, Amanita, and Boletus. In addition, Phlebopus occurs on BCI, and some species in this genus have recently been purported to be ectotrophic (Miller et al 2000). In this paper we report on four Russula species from BCI. We are not certain as to which ectotrophic trees the fungi of these genera might be associated. Several Russula venezueliana collections were made in a dense stand of Swartzia (Caesalpiniaceae) on a small island adjacent to BCI although the mycorrhizal status of Swartzia is unconfirmed for this site. Coccoloba mansanillensis Beurl. (Polygonaceae) forms ectomycorrhizae on BCI (David Janos pers comm), and a number of the collections cited below were found in the vicinity of that species, while some were near C. parimensis Benth. Which other ectotroph tree species are present and possibly form associations with the fungi of the aforementioned genera remains to be determined. |
MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSTAXONOMYDISCUSSIONLITERATURE CITED |
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, Anonymous (1992) and Kelley (1965). Microscopic features were examined and sketched by B. Buyck and compared with type specimens of known South American Russulas. All microscopic observations and measurements—except for basidiospores—were made in ammoniacal Congo red, after a short aqueous KOH pretreatment to improve tissue dissociation and matrix dissolution. Original drawings for all elements of the hymenium or pellis were made at x 2400. In the figures, the long scale line is for the basidiospores and the short one for the other elements. Contents of hymenial and dermatocystidia in the illustrations are indicated schematically, except for a single element where contents are indicated as observed in Congo Red preparations from exsiccata. All elements of the basidiomes were also examined for the presence of ortho- or metachromatic contents or incrustations in cresyl blue as explained in Buyck (1989). Observations and measurements of basidiospores were made in Melzer's reagent. Measurements are given according to Heinemann and Rammeloo (1985) and are based on 20 spores (n) per specimen for each species. The measurements in italics represent the low and high means among the measured collections. The mean length/width ratio (Q) gives minimum, mean, and maximum values. We refer the reader to Buyck (1991) for explanation of cystidial terminology. |
TAXONOMY |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSTAXONOMYDISCUSSIONLITERATURE CITED |
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Basidiospores subglobose to broadly ellipsoidal, (6.7–)7.1–7.36–7.90–8.3(–8.9) x (6.1–)6.3–6.56–6.80–7.1(–7.3) µm, Q = 1.06–1.12–1.16–1.23, n = 30, ornamentation of blunt, cylindrical to acute, conical elements of variable dimensions, many quite large and stout, measuring 1–1.5(–2) µm high, strongly but often partially amyloid, interconnected by a few fine lines, never distinctly reticulate except for young spores; suprahilar plage large and verruculose, decurrent on the apiculus, variably amyloid. Basidia (41–)46–54 x 10–12 µm, clavate, 4-spored; sterigmata stout, 5–7(–8.5) x 1.5–2 µm. Cystidia dispersed to moderately numerous (600–900/mm2) but inconspicuous to very inconspicuous, immerged to slightly emergent, dispersed on lamella edge, quite small, 44–63 x 7–8 µm, narrowly subfusiform, apically tapering to mucronate, thin-walled and fragile, with finely granular to crystalline, refringent contents at least in their central part, scarcely reacting to SV. Subhymenium composed of relatively small, nearly isodiametrical to more globose cells. Lamellar trama with many large sphaerocytes. Pileipellis scarcely delimited from the underlying trama, poorly developed, a loose cutis of narrow, 2–4 µm wide, thin-walled and very long hyphae running often in straight lines on top of the pileus surface (resembling intersecting highways), mixed with the upper sphaerocytes of the trama, some with a distinctly encrusted-glutinous sheath; hyphal extremities not forming an individual layer, differentiated as slightly larger cells that either taper gradually and are hair-like, 1 µm diam, or that are constricted abruptly into a narrow, long appendage; pileocystidia dispersed, lying on the surface or ascending from the underlying trama (but these also very rare), 33–81(–124) x 2–5 µm diam, with granular-refringent contents. Stipitipellis similar to the pileipellis, but hyphal extremities and caulocystidia never appendaged, simply obtuse-rounded, near the base with trichoids composed of long, thin-walled and narrow hyphae 2–3 µm diam; caulocystidia (3–)4–5(–6) µm diam with distinct refringent contents.
Specimens examined. PANAMA. PROV. OF PANAMA: Gatun Lake, Barro Colorado Island, Thomas Barbour Trail, 19 May 1997, Ovrebo 3503 (PMA); Donato Trail 22 May 1997, Ovrebo 3510 (PMA); Lake Trail, 11 Aug 1997, Ovrebo 3606 (PMA). ECUADOR. Napo, Shushufindi, 300 m alt, 15 May 1973, Singer B 7440 (HOLOTYPE!, F) (B 7740 cited in Singer 1975 and B 7400 cited in Singer et al 1983 are typographical errors).
Systematic position.
Russula aucarum is the type-species of section Delicoarchaeae Singer (Singer et al 1983). The distinction, however, between Delicoarchaeae on the one hand, and subsect. Lactariodeae Mre. (= sect. Plorantes Bataille ex Singer) and even sect. Metachromaticae on the other hand, is not clear and is difficult to resolve at present without a better appreciation of the species in the field. The taxonomic importance of the major feature of Metachromaticae, i.e., hymenial cystidia with a thick metachromatic wall in cresyl blue, is overestimated in our opinion. On the other hand, Metachromaticae was considered synonymous with subsection Cyanoxanthinae Singer where strong metachromatic reactions in cresyl blue exist (Buyck 1989, 1992, 1994). This synonymy was partly based on a misinterpretation of the features of R. metachromatica ssp. notoleuca (see below), but re-examination of the microscopic features confirms that Cyanoxanthinae is a different group.
Commentary. The above description, the first report of R. aucarum since the original publication, is based entirely on Panama material and is in agreement with the essential features of the type. Russula aucarum was described from a single collection from a lowland tropical rain forest in Ecuador. The species seems quite well defined by the poor development of the pileipellis, robust sterigmata, decurrent amyloid suprahilar spots on the spores, as well as by the rather dispersed, inconspicuous, narrow, and relatively small cystidia. Both the hymenial macrocystidia and dermatocystidia of R. aucarum are inconspicuous and sometimes very dispersed. Ovrebo 3510 has so few pileocystidia and macrocystidia that rapid examination would easily lead to the conclusion of an acystidiate species.
Because it is the type-species of section Delicoarchaeae Singer (Singer et al 1983), one would suspect that R. aucarum is well characterized and easy to distinguish from other species-groups in the genus. This is not the case. There exist, for example, very strong similarities with Russula metachromatica Singer, described by Singer in 1952 from a collection made by Dennis in a Venezuelan cloud forest. The latter is the type species of the monotypic section Metachromaticae Singer (Pegler and Singer 1980). Metachromaticae is based principally on the presence of thick-walled hymenial cystidia that are metachromatic in cresyl blue. Russula metachromatica is also entirely white but has dispersed, rather rare lamellulae, a shortly sulcate-striate cap margin and taste that is first mild, but quickly becomes subacrid. It also possesses basidiospores with a decurrent, amyloid, suprahilar spot but has a slightly different spore ornamentation. It was later reported by Singer et al (1983) from shady campina and campinarana vegetation with sapotaceous and leguminaceous trees in Brazil, mostly on sandy earth and litter, but also on rotting wood. It was also reported by Pegler (1983) from Martinique and Guadeloupe near polygonaceous and nyctaginaceous trees. Yet, Pegler's photograph of R. metachromatica (1983, Plate 21B) shows a specimen that corresponds much better to the type description for R. aucarum because of the smooth margin and numerous lamellulae.
Singer (Singer et al 1983) later described two subspecies of R. metachromatica from Brazil, each based on a single specimen. Russula metachromatica ssp. notoleuca Singer nom. inval. (no Latin diagnosis) is based on smaller spores and narrower hymenial elements than the type subspecies. It is said to have an acrid taste and different habitat. In an earlier review of type specimens of tropical Russulas (Buyck 1992), the illustrations for extremities of the pileipellis of R. metachromatica ssp. notoleuca (Buyck 1992, fig. 27) were erroneously replaced by those representing similar elements in an African species of Cyanoxanthinae. Although the micromorphological resemblance between spp. notoleuca and the type and Panama collections of R. aucarum is very strong, the former stands out from both R. aucarum and R. metachromatica ssp. metachromatica by the very crowded, narrow lamellae. Together with the acrid taste, numerous lamellulae, and much better differentiated pileipellis, it is a good candidate for a new taxon close to R. aucarum, but better documented (and illustrated) collections are needed for an accurate species interpretation. The second subspecies is Russula metachromatica ssp. tarumaensis Singer 1992 (note the date (!) as the original publication was invalid because of repeated confusion of infraspecific ranks, but all requirements for validation were presented in Buyck 1992, p 60). It was described from Igapo vegetation with Swartzia in Brazil and lacks the thick-walled macrocystidia typical of Metachromaticae, but is otherwise very similar.
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At first, Singer et al (1983) believed R. aucarum to be very close to sect. Archaeinae R. Heim ex Buyck & Sarnari (Sarnari 1998), differing from R. archaea R. Heim only by the presence of hymenial cystidia. The latter was described from coastal forest in Madagascar. Singer (1986) consequently transferred to Delicoarchaeae several other cystidiate species thought to be close to R. archaea. Most of these species were recently discussed by Buyck (1998) and do not belong in Delicoarchaeae. Russula archaea itself is not only very different in the field (see Buyck et al 1998 for color photographs), it is also very different in almost every other character from R. aucarum, although both possess abundant hymenial cystidia. Russula aucarum and R. archaea clearly belong in different sections (Shaffer 1990, Buyck 1992). Russula pusilla Murrill was placed in Delicoarchaeae by Gomez and Alfaro (1996) without explanation. It is, however, very unlikely that this species belongs here because of the pink cap and the equal, white to yellow lamellae.
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Basidiomata solitary or scattered, on soil. Pileus buttons hemispheric and glabrous overall, when mature 30–65 mm wide, plane with slightly depressed center; pellis peeling, dry, sticky when moist, glabrous, quickly becoming finely areolately cracked (10x lens), tuberculate-striate from mid-radius to pileus margin, fissuring radially and exposing the lamellae in between or white context underneath, gray, olive gray, smokey gray (80gy. y Br.-81d. gy. Y Br; 5D3) overall including ridges of sulcations, grooves off-white, occasionally yellowish gray in central area (5C3, 5D4). Lamellae 4–6 mm wide, adnate, rounded at pileus margin, off-white, not discoloring, entire, rather distant (1–1.5 mm apart at mid-pileus), rugulose in between; edge concolorous, often finely serrulate; lamellulae absent. Stipe 30–50 mm long, 5–9 mm thick, equal, dull, glabrous, off-white on upper half, grayish tan below, not discoloring; pithy and chambered inside, eventually becoming hollow. Context 2–2.5 mm thick at edge of pileus disc, off-white, mild, odor absent. Basidiomes not reacting with 2.5% KOH. Spore print white (observed on upper stipe).
Basidiospores subglobose, (6.1–)6.5–6.89–7.3(–7.5) x (5.3–)5.9–6.35–6.8 µm (Q = 1.04–1.09–1.15, n = 20), ornamentation reticulate in young spores and entirely consisting of low crests with short lateral diverticulations, developing into very large conical spines measuring up to 2(–2.5) µm, strongly, but often partially amyloid, remaining interconnected by fine lines into an incomplete reticulum, locally twined or fused in short wings; suprahilar plage large, amyloidity variable. Basidia (41–)46–56 x 12–13 µm, clavate to mostly inflated in central portion, 4-spored; sterigmata stout, 4–5 x 1.5–2 µm. Cystidia dispersed, slightly emergent for ca 20 µm, 68–85 x 10–12(–13) µm, dispersed and small on the lamella edge, e.g., 41–53 x 7–9 µm, subfusiform or subclavate, often with a subapical constriction, capitulate, thin-walled, faintly browning in SV, with granular to crystalline, refringent contents at least in the upper part. Marginal cells dispersed and rare, small, basidiolomorphous but often attenuated at the top or more or less sinuous. Subhymenium composed of relatively small, nearly isodiametrical to irregularly inflated cells. Lamellar trama composed of hyphae and sphaerocytes, many hyphal fragments with oleiferous or rich cytoplasmic contents. Pileipellis two-layered, orthochromatic in cresyl blue, well-developed, a gelatinized subpellis of narrow, 2–4 µm wide, thin-walled hyphae, forming a dense mat close to the underlying trama, containing frequent oleiferous, brown-colored fragments; suprapellis composed of 3–6 strongly inflated, spherical cells, gradually smaller towards the terminal cell, the latter ampulaceous, lageniformous or sometimes developing a long, narrow appendage, in such cases often aggregated in tufts, otherwise resembling an epithelium, part of the cells with a vacuolar brown diffuse pigment; pileocystidia dispersed, terminal, more or less the same diam as other terminal elements, often more clavate, 10–42(–50) x (5–)6–8(–10) µm, some with a 5–15 µm long appendage, contents granular-refringent. Stipitipellis with similar elements as in pileipellis but less aggregated.
Specimens examined. PANAMA. PROV. OF PANAMA: Gatun Lake, Barro Colorado Island, Thomas Barbour Trail, 17 May 2000, Ovrebo 3831 & 26 May 2000, Ovrebo 3898 (PMA); Barbour-Lathrop Trail, 16 May 2000, Ovrebo 3821 (PMA); Miller Trail, 26 May 1997, Ovrebo 3531 (PMA), 14 May 2000, Ovrebo 3805 (HOLOTYPE, PMA; ISOTYPE, PC) & 16 May 2000, Ovrebo 3822 (PMA); Schneirla Trail, 4 Aug 1999, Ovrebo 3706 & 19 May 2000, Ovrebo 3855 (PMA); Shannon Trail, 29 May 2000, Ovrebo 3923 (PC, PMA); Wheeler Trail, 26 May 1997, Ovrebo 3530 (PMA) & 18 May 2000, Ovrebo 3851 (PMA); near "Big Tree," off of Van Tyne Trail, 17 May 2000, Ovrebo 3838 (PMA).
Systematic position.
This taxon belongs in subsect. Pseudoepitheliosinae Buyck (pileipellis features illustrated by Buyck 1990) together with the neotropical R. moyersoenii Buyck and several African Russulas. Subsection Pseudoepitheliosinae differs from the monospecific, neotropical subsect. Epitheliosinae Singer by the presence of true macrocystidia and dermatocystidia.
Commentary.
Russula moyersoenii and R. panamae are very similar. The former was described from baña alta vegetation on sandy soil in Venezuela near trees in the Nyctaginaceae (Neea obovata Spruce ex Heimerl and Ruprechtia sp.) (Buyck 1990). It has a smaller pileus (15–40 mm) that is pale cream to off-white except for a yellow center, and has larger spores with a slightly different ornamentation (Fig. 23). Although both species have yellow pigments in the pileus, the color of R. panamae is more gray to greenish gray and turns entirely gray when dried.
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Compared to R. puiggarii (see below), the subpellis is less developed and composed of slightly narrower hyphae, but is better delimited from the underlying trama by a dense, thin hyphal mat. Some hyphae in the pileipellis contain brown, refringent, oleiferous fragments. There are no transverse, refringent pigment-bands in the cells of the suprapellis, but there is a more diffused, vacuolar brown pigment, which is absent in R. moyersoenii.
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Clitocybe puiggarii Spegazzini, Bol. Acad. Nac. Cienc. Cordoba 9: 389, 1889.
Basidiomata solitary. Pileus 40–50 mm wide, concave or plane and depressed at the center, glabrous, tuberculate-striate from mid-radius to the pileus margin, pellis separable at margin, dark gray to olive brownish gray over the central area and ridges (10 YR 3/3), grooves of sulcations off-white. Lamellae 3–4 mm wide, adnate, off-white, entire, rugulose-pitted in between lamellae; lamellulae absent. Stipe 40–60 mm long, 7 mm thick, equal, faintly longitudinally ridged (10x lens), off-white to very light gray; pithy and somewhat chambered inside. Context of pileus 1.5–2 mm thick, off-white, odor and taste nondescript. Basidiomes not reacting with 2.5% KOH. Spore print not observed.
Basidiospores subglobose, (7.4–)7.7–8.10–8.5(–8.9) x (6.9–)7.1–7.37–7.6(–7.9) µm, Q = 1.05–1.10–1.20, n = 20, ornamentation reticulate in young spores and entirely consisting of low crests with short lateral diverticulations, soon locally developing into large conical spines, up to 2(–2.5) µm high, strongly but often partly amyloid, remaining interconnected by fine lines, forming an incomplete reticulum, rarely twined or fused in short wings; suprahilar plage large, sometimes inamyloid or weakly amyloid and verrucose but more frequently strongly amyloid and thickened in the distal part, surrounded by smaller warts. Basidia (35–)40–50(–55) x 11–12(–13) µm, the smallest ones near the lamella edge, clavate, 4-spored; sterigmata 4–6 x 1–1.5 µm. Cystidia dispersed (400–500/mm2), emergent for 20–30 µm, cylindrical to narrowly subclavate or subfusiform, 60–84 x 7–10 µm, much smaller (31 x 5 µm) near the lamella edge, thin-walled, faintly reddish brown, then graying in SV, with refringent to crystalline contents at least in their upper part. Marginal cells poorly developed, basidiolomorphous or apically attenuated or appendiculate, thin-walled, optically empty, mixed with cheilocystidia and small basidia. Subhymenium composed of small, nearly isodiametrical to globose cells. Lamellar trama with large sphaerocytes and hyphae, with oleiferous fragments and endocystidia near the pileus trama, but not terminating in pseudocystidia, many hyphae distinctly zebroid encrusted. Pileipellis distinctly two-layered, orthochromatic in cresyl blue, a gelatinized subpellis of (2–)3–5 µm large, thin-walled, frequently septate hyphae, with scattered strongly refringent terminal fragments, these often minutely mucronate and about 2 µm diam; suprapellis composed of dispersed, densely septate extremities, containing locally transverse bands of necropigment, composed of slightly larger cells, the terminal cell of the same diam or hardly tapering; pileocystidia of two types: the first broadly clavate, 26–50(–65) x 9–11(–14) µm diam, often appendiculate, the other narrowly subulate, 32–54 x 3–4 µm, minutely capitate, towards the pileus margin descending into the subpellis; both types relatively numerous, terminal, thin-walled, with granular-refringent to slightly crystalline contents. Pileocystidia also observed, but sometimes with much effort and patience, near the subpellis-underlying trama transition, up to 100 µm long, narrowly clavate, capitate to obtuse. Stipitipellis similar to pileipellis in structure. In the upper part the hyphal extremities aggregated in ramified tufts, short-celled, with more inflated, often subglobose to globose or clavate cells, and numerous terminal caulocystidia of the clavate appendiculate type with distinct refringent contents, in deeper layers without caulocystidia, but with distinct, often very large oleiferous hyphae; towards the stipe base with narrower extremities and mostly obtuse, clavate caulocystidia near the surface and longer, cylindrical ones embedded in deeper layers.
Specimens examined. BRAZIL: Rio Grande do Sul, on sandy soil, Rick (FH, holotype of R. brasiliensis), Sao Paulo, Apiai, April 1888, Puiggari (LPS, HOLOTYPE of R. puiggarii). FRENCH ANTILLES: Martinique, Perdrix Plateau, Aug 1976, Fiard 506/F (K, HOLOTYPE of R. hygrophytica). PANAMA: PROV. OF PANAMA: Gatun Lake, Barro Colorado Island, Miller Trail, 14 May 2000, Ovrebo 3809 (PMA); Schneirla Trail, 18 May 2000, Ovrebo 3850 (PMA).
Systematic position.
The systematic placement of this species is problematic for several reasons. Most authors place R. puiggarii in subsect. Discopodinae Heim of sect. Pelliculariae Heim, an invalid name that is best forgotten. Discopodinae was never described at a hierarchical rank, but from the context, it was clear that Heim (1938) considered it a subsection. It was based on Russula annulata sensu Heim, a species for which the various forms and varieties recognized by Heim represent different subsections (Buyck 1994). In addition, the much later described R. discopusHeim (1970) belongs to a different section and probably even subgenus than R. annulata.
Predominantly clavate dermatocystidia are not frequent in tropical Russulas and the only known tropical subsections with such pileocystidia and a similar habit are Inflatinae Buyck and Pseudoepitheliosinae Buyck. Both of these subsections have vividly colored, pink, red to purple or blue species. One entirely brown African species, R. declinata Buyck, is obviously very closely related to R. puiggarii. Notwithstanding the brown color, it was placed in Inflatinae for lack of any better solution (for illustrations and detailed descriptions, see Buyck 1994).
Commentary.
The above description is entirely based on the Panama collections. Russula puiggarii is well characterized by the relatively narrow extremities in the suprapellis and the presence of 2 types of pileocystidia, the first broadly clavate and the second narrowly subulate to narrowly clavate and descending into the deepest layer of the subpellis. It is further characterized by the narrow hymenial cystidia. Russula brasiliensis is certainly a later synonym and corresponds in every way to the type of R. puiggarii. Pegler (1983) retains his R. hygrophytica as an autonomous species, but his argument for doing so is very weak and based on minimal mycoogical and macroscopical differences (200 m elevational difference). Re-examination of the type did not reveal micromorphological differences and we think it is best considered a synonym. The spore dimensions in the description are from Ovrebo 3809. We give for comparison also the measurements of basidiospores for the types of R. brasiliensis: ((7.6–)7.8–8.12–8.5(–8.7) x (7.0–)7.3–7.6–7.9(–8.0) µm, Q = 1.02–1.07–1.15, n = 20) and R. hygrophytica: ((6.9–)7.1–7.44–7.8(–8.1) x (6.5–)6.8–6.97–7.2–7.3 µm, Q = 1.01–1.07–1.13, n = 20).
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Basidiomata scattered or solitary on soil. Pileus 35–110 mm wide, at first convex, then expanding to plane and generally with a depressed center, often concave when old, margin tuberculate-sulcate for about 
to 
radius of the pileus; pellis not easily peeling away, viscid when moist, otherwise slightly greasy or dry, smooth or occasionally rimose or in age areolately cracking at center, subglabrous when dry, brownish gray (10YR 4-5/3, 10YR6-5/3, between 80gy y Br and 77 m y Br, 6D3) to gray (6C2–6D2), the margin often lighter, occasionally discolored brown in spots or areas and often extensively when over-mature, areas covered by leaves remaining off-white. Lamellae 4–9 mm wide, adnate, off-white, occasionally discoloring light brown in areas or spots, pitted-rugulose or often intervenose in between, moderately close (1–1.5 mm apart at mid-pileus), edge concolorous and even; lamellulae absent or occasional. Stipe 35–80 mm long, 9–18 mm thick, equal, base rounded, glabrous but often faintly longitudinally ridged (10x), off-white to very light gray, not discoloring or with occasional brown spots; context solid, occasionally pithy at center and broken into chambers, or hollow, off-white. Context 3.5–7 mm thick at edge of pileus disk, extremely thin on margin, off-white, brittle; taste mild, without odor. Basidiomes not reacting with 2.5% KOH. Spore print not observed.
Basidiospores more or less broadly ellipsoidal, 7.1–7.32–7.5(–7.8) x (6.0–)6.1–6.40–6.6(–6.9) µm, Q = 1.06–1.15–1.19, n = 20, ornaments large, up to 1.5(–2) µm high, conical to rather blunt, strongly amyloid, interconnected by fine lines in an incomplete to complete reticulum; suprahilar plage large and verruculose in the distal part, inamyloid. Basidia small, 38–47(–54) x 9–11.5 µm, clavate to almost subcylindrical, 4-spored, sterigmata stout, 5–6.5 x 1.5–2 µm. Cystidia dispersed to moderately numerous (ca 700–1000/mm2), hardly emergent, dispersed on the lamella edge, quite small, 56–74 x 8.5–12 µm, fusiform to subclavate, thin-walled, with strongly yellowish, oily contents, quickly browning to distinctly graying in SV, exhibiting coarsely crystalline, refringent granules. Marginal cells occupying with some cheilocystidia the entire edge, 16–27 x 4.5–7 µm. Subhymenium composed of relatively large, nearly isodiametrical to globose cells. Lamellar trama almost exclusively composed of large sphaerocytes. Pileipellis two-layered, orthochromatic in cresyl blue, with distinctly zebroid-encrusted elements; subcutis posed on the large sphaerocytes of the underlying trama, gelatinized, with some dispersed oleiferous fragments; composed of rather large, 2.5–5 µm wide, thin-walled, frequently septate hyphae; suprapellis well-developed but disrupted and forming large tufts on the pileus surface, ramifying extremities composed of 3–7 inflated cells, the basal ones distinctly inflated, up to 12 µm diam, gradually tapering to terminal cells, the latter often subcylindrical and usually the longest, many cells with a more or less well-developed lateral "sprout" near the upper septum; pileocystidia quite numerous, 4–5(–6) µm diam, of very variable length, the smallest (generally 20–60 µm long) terminal on septate "hairs," more or less conical to subulate and often minutely capitate, much longer in subpellis or trama, almost cylindrical and obtuse-rounded at the end, with granular-refringent contents. Stipitipellis with more slender and more dispersed hyphal extremities than pileipellis and very numerous caulocystidia; the latter cylindrical, rarely minutely capitate, simply obtuse-rounded or even apically inflated, with yellowish-guttulate contents; hyphal extremities less inflated and less septate than on the pileus, dense to crowded toward the stipe base, with terminal cells in some collections often sinuate, narrowed, almost subulate, and distinctly pigmented.
Specimens examined. PANAMA. PROV.OF PANAMA: Gatun Lake, Island #51 near Barro Colorado Island, 28 May 1997, Ovrebo 3544 (PC, PMA), 15 May 2000, Ovrebo 3813 (PMA), 23 May 2000, Ovrebo 3880 (PMA); Shannon Trail, 17 May 1997, Ovrebo 3487 (PMA), 28 May 1997, Ovrebo 3543 (CSU, PMA), Barbour-Lathrop Trail, 15 May 1997, Ovrebo 3468 (PMA), 18 May 1997, Ovrebo 3497 (PMA); Fairchild Trail, 18 May 1997, Ovrebo 3496 (PMA); Miller Trail, 16 May 1997, Ovrebo 3480 (PMA); Schneirla Trail, 19 May 1997, Ovrebo 3501 (PMA); intersection of Wheeler and Miller trails, 18 May 2000, Ovrebo 3852 (PMA), & 20 May 2000, Ovrebo 3865 (CSU, PMA). VENEZUELA: Caracas, Rio Chaciato, in dry forest, Nov. 1949, Dennis 408 (K, holotype).
Systematic position.
Russula venezueliana was considered to belong in subsect. Diversicolores Singer by its author. However, Buyck (1988) showed Diversicolores to be microscopically very heterogeneous, with the type-species belonging to subsection Amoeninae Singer ex Buyck. Although the systematic position of R. venezueliana is uncertain, subsect. Foetentinae (Melzer & Zvara) Singer might be the best solution for the moment. It also is quite large in comparison with most other "pellicular" species, such as R. moyersoenii or R. puiggarii.
Commentary.
The basidiospore measurements in the description are from Ovrebo 3544 and coincide very well with the mean length/width ratio (7.77 x 6.50 µm, Q = 1.19) of spores from the type collection as measured by Buyck (1988). In the Panama collections, the terminal cells in the pileipellis are generally longer than in the type collections of both R. venezueliana and R. ochrostraminea (Buyck 1988).
Comparison of type collections (Buyck 1992) showed R. venezueliana to be microscopically very similar—if not identical—to R. ochrostraminea described by Pegler (1983) from the Lesser Antilles. Also, R. mephitica Pegler differs from R. venezueliana by a strong foetid smell, while R. marronina Pegler differs by having an acrid taste and developing an odor of bitter almonds. Future field observations should reveal whether the smell and taste are the only differences separating these taxa and whether they are constant enough to be used as diagnostic features at the species rank or would be more appropriate for use at the infraspecific level.
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSTAXONOMYDISCUSSIONLITERATURE CITED |
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, Pegler (1983), Singer et al (1983) and Miller et al (2000) who have collected ectotrophic fungi in the tropical lowlands. In addition, Henkel (1999) has collected ectotroph fungi at slightly higher elevations (700–1000 m). It will be interesting to compare the neotropical ectotroph diversity with the ectomycorrhizal mycota of tropical Africa and Asia where the diversity is seemingly greater (Buyck et al 1996) and is sometimes comparable to temperate ectotroph forests. For example, it has been the experience of the first author to collect several dozens of different Russula taxa on a single excursion day in tropical Africa or Madagascar. Russula venezueliana and R. panamae are the two most common species on Barro Colorado Island. The latter is the only undescribed taxon discovered on the site and is closely related to R. moyersoenii described from Venezuela. Except for R. panamae, the other species have been reported from one or more neotropical countries and likely have wide distributions, ranging possibly from the Lesser Antilles to southern Brazil. One of the major problems encountered in this study was the difficulty of correctly interpreting the various Russulas described from tropical America. At present, descriptions of the neotropical Russulas are often fragmentary and based on a very limited number of collections of each species, often only the type. This makes it very difficult to evaluate variation and/or small differences in characters that always occur between collections, especially when collected over large geographic areas. In this respect, the numerous collections of R. panamae make it possible to appreciate the morphological variation in pileipellis extremities.
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ACKNOWLEDGMENTS |
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FOOTNOTES |
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Accepted for publication May 15, 2002.
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LITERATURE CITED |
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Buyck B., 1988 Etude microscopique de spécimens-types de russules tropicales de la sous-section Diversicolores. Mycotaxon 33:57-70
———. 1989 Utilité taxonomique du bleu de crésyl dans le genre Russula Persoon. Bull Soc Mycol France 95:1-6
———. 1990 New taxa of tropical Russulae: Pseudoepitheliosinae subsect. nov. Mycotaxon 39:317-327
———. 1991 The study of microscopic features in Russula. 2. Sterile cells of the hymenium. Russulales News 1:62-85
———. 1992 Checklist for tropical Russulae and their type specimens. Russulales News special issue 1:1-99
———. 1994 Russula II. Fl. Ill. Champ Afrique Centrale 16:409-539, fig. 258–351, pl. 69–87
———. 1998 Une revision critique de la section Archaeinae (Russula, Russulales). Belg J Bot 131:116-126
———, Eyssartier G, Duhem B., 1998 Contribution à un inventaire mycologique de Madagascar. I. Bull trimestriel Soc Mycol France 114:33-59
———, Thoen D, Watling R., 1996 Ectomycorrhizal fungi of the Guinea-Congo region. Proc of the Royal Soc of Edinburgh 104: (B) 313-333
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Heim R., 1938 Prodrome à une flore mycologique de Madagascar et dépendances. 1. Les lactario-russulés du domaine oriental de Madagascar: essai sur la classification et la phylogénie des Astérosporales. Paris. 196 p, 59 fig., 4 pl
———. 1970 Particularités remarquables des russules tropicales Pelliculariae lilliputiennes: les complexes annulata et radicans. Bull Soc Mycol Fr 86:59-77
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———, Singer R., 1980 New taxa of Russula from the Lesser Antilles. Mycotaxon 12:92-96
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Singer R., 1952 Russulaceae of Trinidad and Venezuela. Kew Bull 7:295-301
———. 1975 Interesting and new species of Basidiomycetes from Ecuador. Beih Nova Hedw 51:239-246
———. 1986 The Agaricales in modern taxonomy. 4th ed. Königstein, Germany: Koeltz Scientific Books. 981 p
———, Araujo I., 1979 Litter decomposition and ectomycorrhizae in Amazonian forests 1. Composition of litter decomposing and ectomycorrhizal basidiomycetes in latosol-terra firme rain forest and in white podzol campinarana. Acta Amazonica 9:25-41
———, Araujo I, Ivory MH., 1983 The ectotrophically mycorrhizal fungi of the neotropical lowlands, especially Central Amazonia. Beih Nova Hedw 77:1-352
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