Darwiniana, nueva serie vol. 1-1

INTRODUCTION

The genus Lactifluus (Pers.) Roussel was proposed after a phylogenetic study of Russula Pers. and Lactarius Pers. by Buyck et al. (2008), who concluded that the genera Lactarius and Russula were weakly supported, and proposed a new genus, Multifurca Buyck & V. Hofstetter, and another group erected later as Lactifluus (Buyck et al., 2010). Later, Verbeken et al. (2011, 2012) and Stubbe et al. (2012) proposed new combinations from Lactarius to Lactifluus, although those combinations did not include any species from Brazil.
Studies in Lactarius in southern Brazil are scarce, and the Priest Johannes Rick firstly referred to it from the state of Rio Grande do Sul. Rick (1906, 1907, 1930, 1938) reported or described Lactarius adustus Rick, Lactarius braunii Rick, Lactarius distans Peck, Lactarius fuliginosus (Fr.) Fr., Lactarius helvus (Fr.) Fr., Lactarius russula Rick and Lactarius steffenii Rick. Later, Singer (1953) confirmed only Lactarius braunii and Lactarius russula as accepted species, and then all taxa were summarized in Rick’s posthumous work published by Priest Balduíno Rambo (Rick, 1961). In recent works, other taxa were reported from southern Brazil, as Lactarius argillaceifolius Hesler & A.H. Sm. var. argillaceifolius, Lactarius deliciosus (L.) Gray, Lactarius fragilis (Burl.) Hesler & A.H. Sm. var. fragilis, Lactarius rufus (Scop.) Fr., Lactarius rufus var. parvus Hesler & A.H. Sm. (these from exotic Pinus plantations) and Lactarius venezuelanus Dennis (Singer et al., 1983; Buyck & de Meijer, 1999; Giachini et al., 2000; de Meijer, 2001, 2006; Sobestiansky, 2005; Karstedt & Stürmer, 2008).
The genus Lactifluus was divided into six subgenera according to Verbeken et al. (2011; 2012), Stubbe et al. (2012), and Sá et al. (2013) ( Table 1 Table 1. Subgenera and sections of Lactifluus (Verbeken et al., 2011, 2012; Stubbe et al., 2012; Sá et al., 2013). ). The section Aurantiifolii was not assigned to any subgenus. One hundred twenty new combinations were performed in the genus Lactifluus in the last years (Verbeken et al., 2011, 2012; Stubbe et al., 2012; Sá et al., 2013).
The studies of the genus Lactifluus in Brazil are very recent and only two species are known for this country: Lactifluus batistae Wartchow, J.L. Bezerra & M. Cavalc. from section Phlebonemi (Wartchow et al., 2013), and Lactifluus dunensis Sá & Wartchow from section Tomentosi (Sá et al., 2013), both from northeastern Brazil. We describe here an interesting Lactifluus as a new species from the southern Brazilian region of Rio Grande do Sul.

MATERIALS AND METHODS

The proposed new species was collected at the State of Rio Grande do Sul, in an Atlantic Forest fragment, in a location called “Perdida”, municipality of Morrinhos do Sul (29º 21’ 30” S, 49º 58’ 35” W), at about 440 to 480 m elevation. The area contains, among others, members of Euphorbiaceae and Myrtaceae (Jarenkow, 1994) that are putative ectomycorrhizal trees (Smith & Read, 2008).
Melzer’s reagent and KOH 3% were used for microscopic studies. Terminology for microstructures followed Verbeken (1998) and Verbeken & Walleyn (2010). Basidiome colors were observed in fresh material, and were coded following Kornerup & Wanscher (1978). For scanning electron microscopy (SEM) studies, sections were removed from dried basidiomata and mounted directly on aluminum stubs using carbon adhesive tabs. The fragments were coated with gold using a sputter coater and examined in Shimadzu SSX-550. Presentation of basidiospore data followed the methodology proposed by Tulloss et al. (1992), and implemented by Wartchow (2012) and Wartchow et al. (2012).
Statistics were based on the measures of 30 basidiospores. Abbreviations included: L(W) = basidiospore lengths (width) average from a single basidiome, Q = length : width ratio range as determined from all measured basidiospores, and Qm = Q value average from all basidiospore measures within a single basidiome.
The electronic version of this article in Portable Document Format (PDF) represents a published work according to the International Code of Nomenclature for algae, fungi, and plants, and hence the new names contained in the electronic version are effectively published under the Code from the electronic edition alone. The online version of this work is archived and available from Instituto de Botánica Darwinion and the digital repositories cited in http://www. ojs.darwin.edu.ar/index.php/darwiniana/about/ editorialPolicies#custom-0.

RESULTS

Lactifluus aurantiorugosus Sá & Wartchow, sp. nov. TYPE: Brazil, Rio Grande do Sul, Morrinhos do Sul, Perdida, 15-V-2009, F. Wartchow s.n. (holotype JPB 52376!, Myco-Bank 803541).

Figs 1,

Fig. 1. Lactifluus aurantiorugosus. A, basidiomes observed in lateral view. B, pileus surface. Scale = 10 mm. From holotype. Color version at http:// www.ojs.darwin.edu.ar/index.php/darwiniana/article/view/520/513

2 y

Fig. 2. Lactifluus aurantiorugosus. A, pileipellis. B, marginal cells. C, pseudopleurocystidia. D, basidiospores. E, basidia, basidiole and subhymenium. Scale = 10 µm. From holotype.

Fig. 3. Lactifluus aurantiorugosus. A-B, basidiospores, as seen with scanning electron mycroscopy (SEM). Scales: A = 5 µm, B = 2 µm. From holotype.

Lactifluus aurantiorugosus differs from other taxa of section Tomentosi in the small size basidiomata, orange and glabrous wrinkled pileus when fresh, distant lamellae, ellipsoid, distinctly verrucose with warts up to 0.7 µm, interconnected with incomplete reticules; pileipellis a trichopalisade, and lamella and pileus trama with abundant sphaerocysts.

Pileus 27-45 mm, plane-convex depressed to deeply depressed, orange (between 68A-68C) sometimes slightly darker (8D8) and margin yellowish (between 4A4-4A5), surface moderately viscid, smooth (shallowly velvety in dried state), radially rugulose-venose; margin entire, incurved in young basidiome and straight and more undulate in older ones; context 4 mm thick at centre, gradually thinning toward the margin; white, unchanging; exuding abundant latex. Lamellae short decurrent, pale cream (1A2 or 1B3), distant, up to 2-3 mm broad, tough; edge smooth, concolorous; lamellulae frequent, attenuating in step to subtruncate, with several lengths. Stipe 24-35 × 7-10 mm, central (only one basidiome more or less eccentric), more or less cylindrical but sometimes tapering toward the base, slightly tapering near the base, pale cream (1B4) sometimes slightly darkening (between 4C5 and 4C6), smooth; context whitish, solid, unchanging. Latex watery white, abundant, unchanging.
Basidiospores (7-)7.5-10.5 × (4.7-)6-8 µm (L = 8.9 µm, W = 6.7 µm, Q = (1.19-)1.22-1.44 (-1.45), Qm = 1.32), broadly ellipsoid to ellipsoid; ornamentation amyloid, finely verrucose with each wart ranging to 0.7 µm high, interconnected by a fine line, but very infrequently forming a complete reticulum; hilar appendix narrowly obtuse to conical. Basidia 69-75 × 8.5-10 µm, slender clavate, bearing mainly four sterigmata 6-10 µm long. Pseudopleurocystidia common, 4-7 µm wide, non-projecting above the hymenium, with brownish refractive contents, thin-walled, arising deeply from hymenophoral trama. Lamella edge with marginal cells 30-45 × 4-6 µm, slender clavate to hyphoid, sometimes sinuous, thin-walled, hyaline, mixed with infrequent basidia. Pileus context with abundant spherocysts, 24-36 × 20-29 µm, globose to subglobose; hyphae filamentous, 2-4.5 µm; lacticiferous hyphae frequent, 3-8 µm, interwoven, common. Subhymenium with shortcelled hyphae about 5 µm wide, sometimes more rounded, frequently branching. Hymenophoral trama heteromerous, with abundant nearly isodiametric cells 15-26 × 13-25 µm, filamentous hyphae 2-5 µm; lacticiferous hyphae 3-6 µm diam., straight, common. Pileipellis trichopalisade, up to 100 µm thick, two layered; elements of suprapellis 20-51 × 4-6 µm, abundant, colorless in KOH 3%, thinwalled somewhat thickening up to 0.5 µm, obtuse, subacute to infrequently subcapitate or piriform; subpellis composed of abundant radially oriented hyphae, 2.5-4 µm wide, colorless. Stipitipellis with thin-walled and interwoven hyphae; caulocystidia absent. Clamp-connections absent.

Etymology. From latin ‘aurantio’ (= orange) and ‘rugosus’ (= wrinkled), regarding to the orange and wrinkled pileus surface of the species.

Distribution and habitat. Only known from the type locality. Widespread on humus soil near to roots of Ficus sp. (Moraceae) in Atlantic Forest of southern Brazil.

Observations. Lactifluus aurantiorugosus can be included in Lactifluus subgen. Lactifluus (Pers.)
Roussel emend Verbeken, sect. Tomentosi (Mc-Nabb) Verbeken on the basis of its orange pileus with somewhat veined/rugulose surface, ellipsoid basidiospores, very long basidia and scarcity of thick-walled pileipellis elements (Verbeken & Walleyn, 2010 as Lactarius). This species is characterized by the persistently wrinkled and non-cracking orange pileus, the contrasting whitish distant lamellae, proportionally shorter stipe compared to the pileus, basidiospores size (7–)7.5–10.5 × (4.7–)6–8 µm (L = 8.9 µm, W = 6.7 µm, Q = (1.19–)1.22– 1.44(–1.45), Qm = 1.32), non emergent and rather scarce pseudopleurocystidia and narrow pileipellis elements.
The recently described Lactifluus dunensis from the State of Rio Grande do Norte, northeastern Brazil, shares the proportionally shorter stipe. However, it differs from Lactifluus aurantiorugosus in several features, i.e. the brownish orange pileus and stipe, light brown lamellae, smaller basidiospores (6.1–)6.6–8.2(–8.7) × (5.6–)6.1–7.1(–7.7) µm, L = 7.5 µm, W = 6.4 µm, Q = (1.00–)1.10–1.40(–1.50), Qm = 1.20 and the pileipellis, as a palisade (Sá et al., 2013). This species also belongs to sect. Tomentosi.
On the basis of the recent taxonomical changes proposed for Lactifluus and Lactarius (Buyck et al., 2008), we postpone the construction of a key to the Brazilian species of Lactifluus until more Brazilian species of Lactarius are reviewed to assess their taxonomical position. For the same reason, Lactifluus auriantiorugosus is here compared to African and North American Lactifluus species.
Among African taxa of this section, at least two species also present orange basidiomes: Lactifluus pseudovolemus (R. Heim) Verbeken and Lactifluus volemoides (Karhula) Verbeken, but they primarily differ in the tomentose rather than wrinkled pileus (Verbeken & Walleyn, 2010 as Lactarius). It is also interesting to note that Brazilian and African species of Lactifluus sect. Tomentosi shares mostly emergent pseudopleurocystidia and presence of spherocytes in the hymenophoral trama (Verbeken & Walleyn, 2010 as Lactarius).
Lactifluus xerampelinus (Karhula & Verbeken) Verbeken from Tanzania, Zambia and Zimbabwe shares with Lactifluus aurantiorugosus the pileipellis structure, i.e. elongate thin-walled cells forming chains, and basidiospores similar in size (7.1–)7.5–10 × 5–7 µm (L = 8.1–8.7 µm, W = 5.9–6 µm, Q = 1.29–1.67, Qm = 1.35–1.48). However, this African taxon differs by the larger (up to 120 mm in diam.), cracking, dark reddish brown pileus and the basidiospores with very low (up to 0.2 µm high) ornamentations (Verbeken & Walleyn, 2010 as Lactarius).
Lactifluus rubiginous (Verbeken) Verbeken, from Tanzania and Zambia, and Lactifluus kivuensis (Verbeken) Verbeken from Africa, also has wrinkled and non cracking pileus and somewhat spaced lamellae, but differ primarily in the presence of reddish brown tinges on pileus and the proportionally longer stipe (Verbeken & Walleyn, 2010 as Lactarius).
Some taxa from the northern Hemisphere are also considered within this group, according to Verbeken (1998). Lactarius echinatus Thiers (not yet combined to Lactifluus) has a yellowish pileus with subtomentose to subpruinose surface, nearly concolorous stipe (Thiers, 1957; Hesler & Smith, 1979); Lactifluus hygrophoroides (Berk. & M.A. Curtis) Kuntze has orange-cinnamon, reddish tawny or dull cinnamon pruinose to minutely velvety pileus, concolorous stipe (Hesler & Smith, 1979 as Lactarius) and inflated elements in the subpellis (Lalli & Pacioni, 1992 as Lactarius); Lactifluus rugatus (Kühner & Romagn.) Verbeken (Hesler & Smith, 1979 as Lactarius) presents pileipellis also with more inflated elements, with thin-walled elements in terminal cells and larger basidiospores (7.8–)8.1–9.5(–9.9) × (5.6–)5.9–6.6(–6.8) µm (Lalli & Pacioni, 1992) than Lactifluus aurantiorugosus.
The North American Lactarius subvelutinus Peck (combination in Lactifluus is not available) shares the orange pileus and basidiospores somewhat similar in size 7–9 × 6.5–7.5 µm. However, it differs in the velvety pileus with a cuticle zone, close and narrower lamellae, presence of cheilocystidia and caulocystidia, and shorter basidia 40–48(–52) × (6–)8–10 µm. In addition, the cells of pileipellis are distinctly shorter and wider 10–25 × 6–15 µm than our new species (Hesler & Smith, 1979).
Another recently described species from Bahia (Brazil), Lactifluus batistae, is characterized by the lack of true cystidia and the basidiospore ornamentation composed of isolated warts, never forming an incomplete reticulum and the hymenophoral trama mainly composed of narrow hyphae. This taxon is classified in Lactifluus sect. Phlebonemi (R. Heim ex Verbeken) Verbeken (Verbeken, 1998; Wartchow et al., 2013), and is phenetically distant from Lactifluus aurantiorugosus (Verbeken, 1998).

ACKNOWLEDGEMENTS

The authors thank “Conselho Nacional de Desenvolvimento Científico e Tecnológico” (CNPq), for providing financial support for the programs “Programa de Pesquisa em Biodiversidade” (PPBio) and “Programa de Capacitação em Taxonomia” (PROTAX). We also thank Dr. Rosa Mara Borges da Silveira for kindly helping us with logistic and collections during field trips; Dr. Paula Santos da Silva and Dr. Mateus A. Reck for help in the collection of the specimens; Dr. Maria Regina Barbosa and TAXON laboratory for the use of facilities; and Dr. Iuri G. Baseia for authorizing SEM studies.

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