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 Add this item to the list  564971 Original description
   
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Remarks (internal):Inocybe caroticolor can be easily recognized in the field by its carrot color, distinct aromatic odor, and entirely pruinose stipe. Microscopically, the basidiospores are nodulose, hymenial cystidia are thick-walled, and caulocystidia descend to the base of stipe. The basidiospore outline is variable. Certain collections or individuals predominately possess weakly nodulose basidiospores (HMJAU 24615, and one basidioma from HMJAU 24614, as in Fig. 1c). However, some collections or individual basidiomata possess predominately strongly nodulose basidiospores with 7-9 nodules (as in the remaining basidiomata of HMJAU 24614, HKAS 38963, and HKAS 36740; see Fig. 1e). An intermediate phenotype also exists (HMJAU 23271, HMJAU 24621, HMJAU 24622 and HMJAU 24623; see Fig. 1d). However, the ITS sequences from HMJAU 24615: GenBank JX025772 and the strongly nodulose-spored material of HMJAU 24614: JX025773 are identical with that from the holotype (HMJAU 23271: JX025774) except for a single base difference in HMJAU 24614. Furthermore, no distinct morphological difference was found among these collections. We consequently interpret the basidiospore shape divergence as intraspecific variation.
Few nodulose-spored Inocybe species resemble I. caroticolor. Inocybe bresadolae Massee has a similar basidiospore shape and sweet smell, but its pileus and stipe have only an indistinct orange tint that is found only in older specimens (Hobart & Tortelli 2009). Furthermore, I. bresadolae has a more robust habit and a context that reddens after cutting (Massee 1904, Horak 1979). An East Asian taxon, I. umbratica f. aurantiaca Takah. Kobay., which resembles the new species to some extent, has a marginate stipe base, fungoid or grassy to spermatic odor, and its type was collected from a Abies mariesii, Pinus koraiensis, and Betula ermanii forest (Kobayashi 2002). Inocybe polycystidiata Kobayasi, described from Japan, also resembles the new species but differs by its subviscid pileus (Kobayasi 1952), recurved pileus scales (Kobayashi 2002), shorter basidia, and smaller basidiospores (Kobayasi 1952 = 5-6.5 x 4.5-5 µm; Kobayashi 2002 = 5.4-7.3 x 4.2-5.9 µm, Q = 1.1-1.5).
Another East Asian species, I. lutea, also resembles the new species. We have examined the authentic materials of I. lutea identified by Hongo (TNS-F-32353, TNS-F-237714), who helped describe the species. Our examinations reveal that it can be distinguished by the following features: (1) the pileipellis hyphae are hyaline with only a slight yellow tinge; (2) the hymenial cystidia are broadly fusiform and slightly thick-walled (1-2 µm thick); and (3) caulocystidia are present only at the stipe apex. An examination of the syntype and additional collections of I. lutea also reveal that caulocystidia are restricted to the stipe apex (Kobayashi 2002). Furthermore, Kobayasi (1952) originally described I. lutea as having a yellow fibrillose stipe that tapers upwards and an “iodinelike” odor.
Lastly, I. lutea as described by Horak (1979, as “Astrosporina lutea” (Kobayasi & Hongo) E. Horak) based on materials from Papua New Guinea is very close to I. caroticolor in basidioma color and entirely pruinose stipe but differs by smaller basidiospores (5.5-8 x 5-6 µm), a burnt horn smell, a marginate stipe base, and a fibrillose pileus with brown fibrils only. Our examinations of a voucher specimen of the Papua New Guinea material (ZT Myc11121) reveal pileipellis hyphae identical to those of I. caroticolor and hymenial cystidia that are predominately utriform usually with a truncate and strikingly thickened base. The Papua New Guinea “Astrosporina lutea” collections appear to share more similarities with I. caroticolor than with East Asian materials of I. lutea. However, “A. lutea” differs from both sets of materials at least by its unique odor.
BLASTn results of our I. caroticolor ITS sequences show one match (95% similarity) with unidentified environmental sequence (Wilson et al. 2008). Also, one sequence by Ryberg et al. (2008) from Estonian material labeled I. aff. grammata reaches 95% similarity.
 
Description type:Original description 
Description:Inocybe caroticolor T. Bau & Y.G. Fan sp. nov. Figs 1, 2
MycoBank: MB 564971
Differs from Inocybe lutea by its hymenial cystidia with thicker walls, its stipe covered uniformly by caulocystidia, and its aromatic odor.
Type: China, Yunnan Province, Kunming, Heilongtan Park, under Quercus variabilis Blume, 26 Aug 2010, Y.G. Fan 2010126 (Holotype, HMJAU 23271; GenBank JX025774).
Basidioma small. Pileus 17-33 mm in diam, conical-convex when young, then plano-convex, dry, with a prominent obtuse umbo, covered with appressed squamules, radially arranged, fibrillose, rimulose to usually rimose at margin, margin inrolled when young, occasionally recurved when mature, orange (5A7- 8) to apricot (4A7-8), squamules concolorous when young, then turning brown (5C8) to reddish brown (6C8), background orange-apricot (4A8) to ochraceous (3A6). Lamellae adnexed, moderately crowded, up to 3 mm in width, pale orange to apricot (4A7-8) when young, dirty apricot (4B7) to brown (5B7) when mature, gill edge concolorous or paler, not smooth. Stipe 30-42 x 2-3 mm, solid, pale orange (5A6) to apricot (4A7), equal with subbulbous to nonmarginate bulbous base, occasionally base distinctly wider, entirely pruinose on the stipe surface, densely pruinose at upper part, longitudinally striate downwards, stipe base with whitish tomentum. Cortina absent. Context with conspicuous aromatic odor, fleshy in pileus, whitish to pale apricot (4A5), 1-3 mm in width, striate in stipe, pale apricot (4A5).
Basidiospores 6.3-9.3(-9.5) x (4.4-)4.7-6.0(-6.2) µm, Q = (1.43-)1.47- 1.58(-1.61), weakly to prominently nodulose (with 7-9 nodules), yellowish brown. Basidia 24-37 x 5-9 µm, with 4 sterigmata, occasionally with 1 or 2 sterigmata, clavate, narrower downwards, at times slightly enlarged at the base, usually with yellowish pigments. Pleurocystidia 48-63 x 12-16 µm, fusiform with obtuse apices, occasionally utriform, crystalliferous at apex, base obtuse or tapering into pedicel, walls bright yellow, 2-3(-4) µm thick, hyaline inside, rarely with yellow pigments. Cheilocystidia similar to pleurocystidia, more variable, occasionally cylindric; Paracystidia abundant among cheilocystidia, clavate to obovoid, thin-walled, hyaline, mixed with basidia. Caulocystidia descending to stipe base, 48-79 x 9-14 µm, abundant, similar to pleurocystidia, but more variable in shape, usually with slender habit and thinner walls (0.8-2.4 µm); Cauloparacystidia abundant, thin-walled, fusoid to lageniform, at times apex tapered, mixed with filamentous hyphae. Pileipellis a cutis, composed of cylindric, smooth hyphae 2.0-7.0 µm wide, regularly arranged, with oil-yellow to dark-yellow intra-hyphal pigments in upper layer, almost hyaline in lower layer. Clamp connections present in all tissues, but not at every septum.
Habitat and ecology: Singly in groups, common in roadsides near forests, all known collections under Quercus variabilis except for one (HKAS 38963) under Pinus yunnanensis. June to August in Yunnan, China.
 
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