Perenniporia podocarpi P.K. Buchanan & Hood 1992
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Biostatus
Nomenclature
Classification
Synonyms
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Descriptions
Perenniporia podocarpi P.K. Buchanan & Hood 1992
New Zealand: Stewart I., vie. Halfinoon Bay, Garden Mound Scenic Reserve, on dead fallen branch of Dacrydium cupressinum Lamb., P.K. Buchanan 85/183, R. Block, 23.iv.1985, PDD 50607 (holotype).
Additional Specimens Examined: New Zealand: Taupo, Whirinaki Forest Park, vie. Minginui, on Dacrydium cupressinum, I,A. Hood, 18.X.1983 (NZFRI 3088M); Westland, Okarito State Forest, PX. Buchanan, 25. iv. 1987 (PDD 58346); Bay of Plenty, Te Whaiti, on Prumnopitys taxifolia, G.B. Rawlings, ix.1949 (NZFRI 2045 M).
Basidiocarp perennial, resupinate, adnate, effused to cushion-like, starting as irregular patches, reaching up to 90 x 40 mm, 3-13 mm thick, with an abrupt, up to 0.5 mm wide, whitish to pale creamy, velutinous margin. Pore surface even, creamy to pale greyish orange. Pores round to angular, ellipsoid to radially elongated on oblique surface or near the margin, 1 or 2 per mm, 400-950 µm wide. Dissepiments thick, entire, 100-500 µm thick. Tube layer indistinctly stratified, with a hard corky consistency, cork-coloured, pale greyish orange to greyish orange, up to 12 mm thick, individual layer up to 4 mm thick (fide Buchanan and Hood 1992). Subiculum reduced to a thin layer, up to 1 mm thick, creamy to greyish orange.
Hyphal system di-trimitic. Generative hyphae hyaline, clamped, thin-walled, 1.5-3-(4.5) µm wide (fide Buchanan and Hood). Vegetative hyphae hyaline to faintly yellowish, variably dextrinoid (the more branched hyphae close to the hymenium are more dextrinoid than the less branched to unbranched hyphae from the deep trama), cyanophilous.
Subiculum and trama of the tubes with non-to sparingly-branched skeletal hyphae, arising from generative hyphae, with a basal clamp, the basal part sometimes geniculated, with a few short lateral processes, commonly aborted, the main part unbranched, or branching once dichotomously, thick-walled, gradually widening from 1.7-2.3 µm wide at the basal septum to (2.6)-2.9-4.0-(4.5) µm in the main part (x = 3.4 µm), with a narrow to collapsed lumen. More branched hyphae, binding-like, close to the hymenium and invading the tubes, narrow, laxly branched, cyanophilous, not to strongly dextrinoid, 1-1.5 u,m wide.
Basidia 35-50 x 12-16 µm (24-37 x 11-15 µm, fide Buchanan and Hood 1992 ), urniform, constricted, hyaline, thin- to occasionally faintly thick-walled in the basal part, with abasal clamp and four broad sterigmata. Basidioles 29-35 x 11-14 µm, clavate, thin- to occasionally slightly thick-walled. Basidiospores (15.5)-16.4-23.0-(24.0) x 7.5-9.6- (10.0) µm (15-27 x 7-11 µm, Buchanan and Hood 1992), R= 1.7-3.0 (x = 19.9x 8.5 µm, xR = 2.3), ellipsoid to cylindrical, occasionally slightly curved, apex rounded to (sub)truncate, apiculate, thick-wailed with an apical germ pore, hyaline, dextrinoid, cyanophilous. Cystidia and chlamydospores absent.
Type of Rot: white rot.
Cultural Features: unknown.
Sexuality: unknown.
Perenniporia podocarpi is remarkable because of its thick, whitish to creamy, resupinate basidiocarp, large pores (I or 2 per mm), dextrinoid vegetative hyphae, long, urniform basidia, and large (15-24 x 7-10 µm), ellipsoid to cylindrical, thick-walled, apically (sub)truncate, strongly dextrinoid basidiospores. There is no other Perenniporia species with this combination of characters, and P. podocarpi remains isolated within the genus. Perenniporia ochroleuca has large (up to 20 µm), ellipsoid, apically truncate basidiospores, which are occasionally yellowish. It differs by having a pileate basidiocarp habit, smaller pores, a differing hyphal system, and clavate to more commonly shortly pedunculate (pyriform) basidia (Ryvarden and Johansen 1980; Corner 1989). Buchanan and Hood (1992) did not discuss their generic assignment, which undoubtedly was based on adimitic hyphal system with dextrinoid vegetative hyphae and thick-walled, (sub)truncate, dextrinoid basidiospores, both features which in the current broad circumscription of the genus support this choice.
Within the existing genera of polypores (Ryvarden 1991), Phaeolrametes Lloyd ex Wright, typified by P. decipiens (Berk.) Wright (Wright 1966), has some morphological similarities with P. podocarpi. Phaeolrametes decipiens is characterised by a resupinate (then thick), effused-reflexed to pileate basidiocarp with a light to dark pinkish brown context and tube layers and large pores. The hyphal system is dimitic, with yellowish brown, sparingly branched skeletal hyphae. Basidiospores are large (up to 25 µm long), ellipsoid, apically truncate, thick-walled, with or without an apical germ pore, hyaline when young, yellowish or brownish when mature (Wright 1966; Fig. I Od). The basidia are rather long, urniform or constricted, occasionally slightly thick-walled, especially in the basal part (CD, pers. obs., Fig. 10c). Wright (1966) noted that the genus was isolated within the polypores, and Ryvarden (1991) suggested a relationship with Perenniporia, based on the peculiar truncate basidiospores.
The distinction between Phaeolrametes and Perenniporia is unclear, due to the peculiar combination of characters found in the former, which may also occur individually in species of Perenniporia. Ryvarden (1991) differentiated Phaeolrametes from Perenniporia primarily by the tinted basidiospores and chlamydospores of the former. However, basidiospores can be occasionally tinted in some Perenniporia species (e.g. P. ochroleuca described with 'golden' basidiospores (Ryvarden and Johansen 1980), or P. tephroleuca with hyaline to yellow or pale brown basidiospores (Ryvarden and Johansen 1980; Gilbertson and Ryvarden 1986, 1987; Corner 1989). The urniform basidium also seems to separate Phaeotrametes from Perenniporia. However, the shape of basidia is rarely used in polypore taxonomy. In most genera, they are little differentiated, clavate and with four sterigmata (Gilbertson and Ryvarden 1986; Ryvarden and Gilbertson 1994). In most Perenniporia, as well as in Ganoderma P.Karst, the basidium is commonly shortly pedunculate (pyriform). Basidial morphology is considered important in taxonomy of'corticiaceous' fungi, where several genera are partly based on this feature. Perenniporia podocarpi, with its thick resupinate basidiocarp, steep margin, and large pores resembles the resupinate basidiocarp of Phaeotrametes decipiens, from which it seems to differ only in colour, white to creamy and brown respectively. Microscopically, both taxa share a dimitic hyphal system, similar constricted basidia with broad sterigmata, and similar, (sub)truncate basidiospores with an apical germ pore. Although hyphal pigmentation has been widely used in the past to segregate polypore genera, its taxonomic value is questionable. Perenniporia contains species with hyaline and pigmented vegetative hyphae (e.g. P. medullapanis and P. tephropora with hyaline and brownish vegetative hyphae, respectively). Perenniporia podocarpi is considered a marginal species within Perenniporia, based on grossly different basidiocarp habit and basidial and basidiospore morphology. Whether the peculiar combination of characters found in both P. podocarpi and P. decipiens is an indication of relatedness, or of a convergent evolution remains unclear. The relationship between Phaeotrametes and Perenniporia remains also uncertain. Until more data, including molecular data, becomes available, we will refrain proposing any new combination, and maintain both taxa in their respective genera.