Monographs Details: Hexagona hydnoides (Sw. & Fr.)
Authority: Fidalgo, Oswaldo & Fidalgo, Maria E. 1968. Polyporaceae from Venezuela. I. Mem. New York Bot. Gard. 17 (2): 1--34.
Family:Polyporaceae
Description:Species Description - MACROSCOPIC CHARACTERS: Fruiting body annual to very rarely perennial, solitary to imbricate, always sessile, usually attached to the substrate by a small pilear portion, which is usually much thicker and more resistant than the rest of the fructification; pileus dimidiate, flabelliform, slightly convex to applanate, 3-19 X 2.5-10 (-14) X 0.5-1 (-2.2 ) cm, coriaceous and flexible when fresh, ligneous and rigid on drying; pilear surface always some shade of brown, usually IMP-15A8 (Cashew Nut) to blackish, densely strigose. covered by a compact layer of dark brown to black, branched hairs; hairs usually erect but sometimes also prostrate, 1-3 (-8) mm long, usually not deciduous, but sometimes falling off in zones, giving to the pilear surface an aspect of being concentrically zonate, rarely becoming glabrescent; margin slightly curved downwards to ajoplanate, thin, acute, rigid, concolorous with the pilear surface, entire to lobate. Context coriaceous, radially fibrous, at times marked by concentric zones, permanently darkening in KOH solution, subhomogeneous. shiny, cinnamon-brown, MP-8L6 (Mirador), MP-14E8. (0.5-) 1-10(-14) mm thick. Hymenial surface olive-brown or beige, MP-15E10 (Olive Wood) to MP-14B7 (Blondine). always poroid, never daedaloid, irpicoid or lamellate, with circular to subcircular pores, very constant in size. 3-4(-5) per mm: tubes pruinate. brownish to grayish, MP-14E8(Dogwood) to MP-14C6 (Caucasia-h), unistratified, rarely in several indistinct layers, 0.1-0.5(-1) cm long; dissepiments alwavs thick, entire, obtuse, 40-160 µ thick. MICROSCOPIC CHARACTERS: Pilear surface characterized by a welldeveloped, fasciculated trichoderm, with very long, branched dark hairs, stiff-erect to prostrate, 1000-3000 (-8000) µ long, 200-450 µ diam, formed by tufts of yellowish-brown, parallel skeletal hyphae starting at the surface of the pileus and running periclinally, then raising up obliquely and afterward becoming anticlinal; with age the hairs partially falling off and the pilear surface appearing as if covered by an indistinct cutis, formed by the outer hyphae of the context, becoming agglutinated; usually a differentiated plectenchyma surrounding the base of the hairs in the context, 60-320 µ thick, formed by short, branched generative hyphae and binding hyphae, loosely interwoven; this structure sometimes limited not only to the point of attachment of the hairs but also continuing to some extent up the length of the hair, delimited by a thin, dark line, 3-5.5 (-6.5) µ thick, formed by the outer hyphae of this plectenchyma agglutinated in a compact way. Context and dissepiments formed of a trimitic hyphal system. Generative hyphae hyaline, thin-walled, septate, with clamps, branched, nonamyloid, 2-2.5 µ diam; skeletal hyphae yellowish-brown to brown, thickened but usually with a distinct lumen, not septate, unbranched, at times with a few, delicate, simple septa near the apical region, walls straight to somewhat flexuous. 3-5.5 µ diam; binding hyphae subhyaline to yellowish, thickened to subsolid, much branched, not septate, 1.5-2 (-2.5) µ diam. Context when viewed in section presenting a loose, fibrose, upper part, with most of the hyphae running periclinahy, the skeletal hyphae being the predominant type, and a thin and much compact lower layer formed by the three types of hyphae equally abundant and arranged without a definite orientation. Dissepiments formed of the three types of hyphae, closely interwoven and without a definite orientation. Hymenium: setae, cystidia, cystidioid hyphae or pseudosetae absent; hyphal pegs yellowish-brown to brown, conic, abundant, (35-) 40-65 (-80) X (20-) 30-50 µ. Basidioles clavate, hyaline, 9.5-23 X 6-9 µ; basidia clavate, hyaline, 9-10 µ diam, collapsing very early, leaving a honeycombed structure; basidiospores hyaline, cylindric, smooth, nonamyloid, (9-)11-13.5(-15) X (3-)3.5-1.5(-5) µ.

Discussion:

Figs. 28-32, 61-65.

Bejletus hydnoides [Sw.. Nov. Gen. S]). Plant. Prodr. Descr. Veg. 149. 17881.

Polyporus hydnoides (Sw.) ex Fr., Syst. Mycol. 1: 362. 1821.

Trametes hydnoides (Sw. ex Fr.) Fr.. Epicr. Syst. Mycol. 490. 1838.

Polystictus hydnoides (Sw. ex Fr.) P. Henn.. Hedwigia 43: 178. 1904.

Pogonomyces hydnoides (Sw. ex Fr.) Murr.. Bull. Torrey Club 31(10): 609-610. 1904.

Boletus hydnatinus [Bose. Ges. Nat. Freunde Berlin Mag. 5: 84. 1811]. Type from South Carolina, U.S.A. (teste Fries, 1828: 107).

Polyporus hydnatinus (Bose) ex Fr.. Syst. Mycol. 1: 362. 1821.

Polyporus pellitus [G. Meyer. Fl. Esseq. 303. 1818]. Type from K. Esequibo River, British Guiana (teste Saccardo, 1888: 346).

Polyporus pellitus G. Meyer ex Fr.. Syst. Mycol. 1: 362. 1821.

Boletus crinitus [Spreng., K. Svenska VetenskAkad. Handl. 1820: 51. 1820]. Type from Puerto Rico (teste Fries, 1828: 107).

Polyporus crinitus (Spreng.) ex Fr.. Syst. Mycol. 1: 362. 1821.

Boletus fibrosus Hook, in Kunth, Syn. Pl. 1: 10. 1822. Type from Andes, between Popayan and Almaguer, Colombia.

Trametes fibrosa (Hook, in Kunth) Fr., Epicr. Syst. Mycol. 490. 1838.

Trametes ocellata Berk. & Curt.. Jour. Linn. Soc. Bot. 10: 319. (1S6S) 1869. Type from Cuba (teste Murrill, 1908c: 84).

Polyporus jeathermanni Rav. in Cooke. Grevillea 6(40) : 130. 1878. Type from Gainesville, Florida. U.S.A.

Trametes jeathermanni (Rav. in Cooke) Cooke. Grevillea 14(74): 55. 1886.

Polyporus verrucoso-hirtus Speg., Anal. Soc Cit. Argent. 17: 46. 1884. Type from Guarapi, Paraguay (teste Bresadola, 1916: 228).

Type. Holotype collected by Swartz at herbarium Thunberg (UPS) sheet 27237, labelled as Boletus hydnoides Swartz.

Type Locality. Jamaica, West Indies.

Basionym. Polyporus hydnoides (Sw.) ex Fr., 1821.

Illustrations. Bose, Ges. Nat. Freunde Berlin Mag. 5: pl. 4, fig- 2, a-d. 1811 (as Boletus hydnatinus); Tavares, Bol. Seer. Ind. Com. Pernambuco 1939: figs. 47-48. 1939 (as T. fibrosa); Overholts, Univ. Alich. Stud., Sci. Ser. 19: pl. 48, figs. 288-289; pl. 130. 1953 (as P hydnoides); L o w y and Welden, Amer. Midi. Nat. 6 1 : fig. 6. 1959 (as P. hydnoides).

Discussion. After studying H. hydnoides. the type was located. I had accepted the name in the traditional sense of Polyporus hydnoides. as used by Overholts (1953: 397). This decision agreed with the type. I examined the holotype of Boletus fibrosus Hook, in Kunth (deposited at K) and found it conspecific with H. hydnoides, as was indicated earlier by Murrill (1908c: 84); the type of B. fibrosus is a small specimen, almost black, with the surface washed off, with few hairs, pore surface dark brown, with 3.5-4 (-51 pores per mm. The name T. fibrosa is applied in herbaria generally to specimens with dark brown hairs, nearly concolorous with the abhymenial surface, over which the hairs become more or less prostrate. The name P. hydnoides is generally applied to specimens with black and erect hairs, arranged in a more dense way. Casually the collections are quite uniform showing one or the other aspect; however I have seen specimens also with intermediate color and position of hairs as well as several collections where both aspects were clearly recognized. I think that they are just morphological forms of one species.

The inclusion of Hexagona hydnoides in Hexagona Fr. emend, proved to be necessary since the detailed study of H. apiaria, H. hirta and H. pobeguini indicated that they are undoubtly related to H. hydnoides. In the emendation of genus Hexagona, Pogonomyces Murr. appears to be superfluous. The association of H. hydnoides with species of Hexagona was suggested earlier by several authors: (1) Boletus fibrosus (one of the synonyms of H . hydnoides) was described by Hooker (1822: 10) as similar to P. hydnoides and differing from H. hirta by having smaller pores; (2) Saccardo (1888: 347) suggested that Trametes hystrix (one of the synonyms of H. hirta) was closely related to P. hydnoides and T. fibrosa; (3) Patouillard (1900: 92) indicated that Hexagona was closely related to Trametes through the close relationship observed between sect. Setosus of Hexagona (including H . hirta, H. apiaria, H. capillacea, etc.) and sect. Fibrosus of Trametes (including T. hydnoides, T. aspera, T. fibrosa, etc.); (4) Lloyd (1916b: 612) considered the existence of a line of continuous variation among H. apiaria, H. hirta and T. hydnoides; (5) Donk (1933: 197) indicated Pogonomyces and Hexagona as closely related genera; (6) Fidalgo and K. Fidalgo (1962: 198-201) concluded that H. apiaria, H. hirta and P hydnoides were closely related species, P. hydnoides, however, having a more complex structure of the pilear surface. Recently Donk (1964: 281) included Pogonomyces in the synonymy of Hexagojia Fr. [cited as Scenidium (Kl.) 0. Kuntze]. I have reached the conclusion that Hexagona is the best place for P hydnoides after comparing its structure with those of H. apiaria, H . hirta, H. aspera and especially with that of the African fungus, H. pobeguini. I noticed that in the pilear surface of H. pobeguini a plectenchymatic structure sometimes is present also which resembles the formation that Fidalgo & K. Fidalgo (1962: 200) first noted in H. hydnoides. At that time it was supposed not to be found in genus Hexagona but only in Pogonomyces. In H. pobeguini this structure is not as conspicuous as in H. hydnoides and is comparatively thinner, probably consisting of generative hyphae. In addition to the latter observation, I believe that the hyphal system, the way the hyphae are distributed in the context, the dark context, the fasciculated trichoderm associated with a cutis, the occurrence of dark colored hyphal pegs, the shape of basidiospores, the honeycombed basidia, and the way the pileus is attached to the substrate are characteristics that indicate a strong relationship of H. hydnoides with the typical species of Hexagona Fr. emend. Among these species H. hydnoides appears as closely related to H. hirta f hystrix, a form formerly considered an independent species. While H. hirta appears to be a highly polymorphic species, H. hydnoides is comparatively much more stable. In the size of pores, H . hirta presents a range of (3.5-) 4-15 (-23) pores per cm while H. hydnoides shows less variation with a range of 3-4 (-5) pores per m m. I suspect that some of the records of H. hydnoides from Africa were based upon misdetermined specimens of H. hirta f hystrix. H. hydnoides can be separated from H. hirta i hystrix by the following characteristics: (1) Skeletal hyphae of the upper layer of the context are slightly thinner than those found in H. hirta. (2) Hyphal pegs are smaller than those found in H. hirta. (3) Dissepiments are thinner. (4) Pores are smaller. (5) A dimitic, plectenchymatic, hyphal structure may be found around the insertion of the hairs of the pilear surface of H. hydnoides but is not found in H. hirta.

H. aspera is another species that has small pores and tubes sometimes disposed in more than one layer. It is easily distinguished from H. hydnoides because it loses the hairs of the pilear surface very early becoming glabrescent and has skeletal hyphae of a larger diameter.

Boletus ursinus [Link, 1809: 38-39] described from Brazil was indicated bv Fries (1838: 490) as closely related to P hydnoides and considered by Bresadola (1916: 229) as a mere synonym of it. Fidalgo & K. Fidalgo (1967: 881) have indicated this name as "nomen dubium" until a type can be found. The collection that Fries (1848) listed from Natal, South Africa, is not H. hydnoides; there is a fragment of it at BPI (Lloyd 53400) which seems to be a specimen of Funalia sp. Boletus vulpinus [Link, 1809: 39] was described from Brazil as a possible young stage of Boletus ursinus and indicated by Fries (1838: 490) as closely related to P. hydnoides. Later on, the name P. vulpinus was used by Fries (1874: 565) to describe a new species. Fidalgo & K. Fidalgo (1967) have recommended that B. vulpinus [Link] be considered also as "nomen dubium" until a type is found.

In herbaria I found two unrelated species that are sometimes misdetermined as H. hydnoides: Polyporus trichomallus Berk. & Mont, and Polyporus cirrhiferus Berk. & Curt. Both occur in tropical areas and have a conspicuous, strigose pilear surface. P trichomallus has black, branched hairs, disposed in a compact way and with almost no context; the pileus is broadly attached to the substrate; capitate cystidia are found in the hymenium and the basidiospores are oblongcylindric to shortly cylindric, much smaller than those found in H. hydnoides. P. cirrhiferus has reddish-brown, prostrate hairs, also disposed in a compact way but the context is thicker and separated from the trichoderm by a thin, black line; the context is not brown but cream to beige; skeletal hyphae are hyaline to yellowish; the hymenium is interrupted by frequent hyphal pegs, which are hyaline and very slender, made up only by generative hyphae; basidiospores are cylindric but smaller than those of H. hydnoides.

Habitat, Hosts and Economic Importance. Hexagona hydnoides is usually found on dead wood such as dead branches of living trees, old stumps, railway ties, poles, fence posts, etc. And apparently this fungus can become a parasite. I collected it once in Guanabara State, Brazil, growing abundantly on trunks of living trees of Ficus retusa L. and I found collections in BPI and FH labelled as found on living oak, Quercus sp., in Florida; also in BPI there is a collection from Tortola, Virgin Is., which was labelled as being found on a growing tree of Tamarindus indica L.

Hexagona hydnoides seems to occur in altitudes up to 2000 m and also at sea level, north and south of the Equator. Some of the collections that I have seen were labelled as having been found in dense and humid forests of Brazil, Peru and Venezuela; however, most of the collections appear to be from dry areas. In Brazil I found it very common in the dry savanna ("cerrados"), either of the open or close types ("cerradoes''). Wolf (1949: 215) reported it from Venezuela as "manifestly xerophytic" and Guzman (1963b: 51) reported it from the arid zone of Nuevo Leon, Mexico.

H. hydnoides has been listed in literature as growing on dead wood of Acacia sp. in Venezuela (Patouillard & Heim, 1928: 269), Anacardium occidentale L. in Dominican Rep. (Ciferri, 1961: 102), Byrso7iima sp. in Sao Paulo, Brazil (Fidalgo, K. Fidalgo & Furtado, 1965: 60), Carya sp. in Florida (Overholts, 1953: 398), Casuarina equisetifoUa L. in Florida (Hedgcock, 1940: 325; Overholts, 1953: 398), Citrus sp. in California [?] (Weiss, 1941: 40), Gleditsia sp., Juglans sp. and Liquidambar sp. in Florida (Overholts, 1953: 398), Malpighia urens L. and Mimusops balata Craig ex Griseb. in ^Martinique (Patouillard in Duss, 1903: 29), Pithecolobium saman (Willd.) Benth. in British Guiana (Wakefield, 1934: 250), Platanus sp., Prosopis sp. and Quercus sp. in Florida (Overholts. 1953: 398), Samanea saman (Jacq.) Merrill in Trinidad (Rayner, 1941: 6; Baker and Dale, 1951: 82), Sloanea surinameiisis in IMartinique (Patouillard ill Duss, 1903: 29) and on Ulmus sp. in Florida (Overhohs, 1953: 398).

Some of the collections that I studied were labelled as found on dead wood Acer floridanum Pax. in Texas (BPI), Albizzia lebbek Benth. in Florida (FH), Anacardium occidentale L. in Dominican Republic (BPI), Astronium balansae Engl, in Argentina (BPI), Carya ilUnoensis C. Koch in Florida (BPI), Carya olivaeformis Nutt. in Texas (BPI), Casuarina sp., in Bahamas (NY), C. equisetifoUa L. in Florida (BPI), Cecropia sp. in Amazonas, Brazil (BPI), Celtis sp. in Texas (BPI), Citrus sp. in Florida (BPI, FH), C. aurantifolia Swingle in Florida (BPI), C. medica L. in Florida (BPI), Comocladia dentata Jacq. in Cuba (BPI, FH), Cupressus sp. in Florida (BPI, NY) and in Kansas (BPI), Dichrostachys nutans Benth. in Cuba (BPI), Ficus sp. in Honduras (BPI), F. retusa L. in Guanabara, Brazil (RBM, SP), Flacourtia ramontchii L'Her. in Guadeloupe (FH, NY), Fraxinus berlandiera DC. in Texas (BPI), Gleditsia sp. in Louisiana (BPI, NY), Guazuma ulmifolia Lam. in Cuba (FH), Hevea sp., in Para, Brazil (BPI), H. brasiliensis Mueh. in Amazonas, and Para, Brazil (BPI) and in Vera Cruz, Mexico (BPI), Inga sp. in Costa Rica and Honduras (BPI, FH), Inga vera Willd. in Puerto Rico (BPI), Jacaranda mimosaefolia G. Don in Colombia (BPI), Juglans nigra L. in Texas (BPI), J. rupestris Englem. in Texas (BPI), Leucaena glauca Benth. in Florida (BPI), Magnolia sp. in Martinique (BPI), Malpighia urens L. in Guadeloupe (FH, NY), Mangifera indica L. in Florida (BPI), Mimusops balata Craig ex Griseb. in Martinique (FH), Myristica surinamensis Rol. in Trinidad (NY), Ocotea catesbyana (Michx.) Sarg. in Florida (BPI), Persea gratissima Gaertn. (as P. americana Mill.) in Florida (FH), P. palustris (Raf.) Sarg. in Florida (BPI), Firms caribaea Morel, in Florida (FH), Pithecolobium saman (Willd.) Benth. in Cuba (FH), Platanus sp. in Texas (BPI), Poinciana sp. in Florida (BPI), Prosopis sp. in Texas and Argentina (BPI), P. juliflora DC. Willd. in Puerto Rico (BPI), Jacaranda mimosaefolia D. Don in Colombia (BPI), Prunus persica Stokes in Texas (BPI), Quercus sp. in Florida (BPI, FH), Q. alba L. in Texas (BPI), Q. myrtifolia Willd. in Florida (NY), Q. phellos L. in Texas (BPI), Q. texana Buckl. in Texas (BPI), Q. virginiana Mill, in Florida (BPI), Sambucus sp. in Rio Grande do Sul, Brazil (BPI), Sideroxylon mastichodendron Jacq. in Florida (BPI), Theobroma cacao L. in Trinidad (NY) and Amazonas and Para, Brazil (BPI), and Ulmus crassifolia Nutt. in Texas (BPI). In addition, one collection had been collected on an old stump in a coffee plantation in Trinidad (NY), several were found on dead coconut trunks in El Salvador (FH) and in Trinidad (NY) and, one collection (G. Eiten & L. T. Eiten 4823) was found on dead wood of a "cagaita" tree in Maranhao, Brazil (SP), which according to the collectors is a member of the Myrtaceae and probably Stenocalyx dysentericus Berg.

North America Hexagona hydnoides is found in a few states of United States and in several parts of Mexico. It is known and abundantly collected in Florida, Texas and Louisiana. It is reported here for the first time, apparently, from Kansas, growing on Cupressus sp. There is also a report from California by Weiss (1941: 40) of it growing on Citrus sp. and the record of Bose (1911) of Boletus hydnatinus from South Carolina, but these records are still not confirmed. In Florida the species is usually found in a kind of vegetation called hammocks, where there is a predominance of hardwood trees and the soil has a greater depth than observed in areas covered by softwood trees. From Mexico I have seen collections from states of Colima, Oaxaca, Nuevo Leon, San Luis de Potosi, Quintena Roo, Vera Cruz and Yucatan; Guzman (1963a: 32; 1963b: 51) reported it also from states of Guerrero, Jalisco, Puebla and Tabasco.

H. hydnoides is extremely common in the AVest Indies Avhere it has been found in the Bahamas, Cuba, Dominican Republic, Haiti, Jamaica, Puerto Rico, Leeward Is. (Guadeloupe, St. Kitts, IMontserrat), Virgin Is. (St. Croix, St. Thomas. Tortola), Windward Is. (Dominica, ^Martinique, St. Vincent) and Trinidad. From Central America I have seen collections from British Honduras, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua and Panama. H. hydnoides is also very common in South America where it occurs in Argentina (northern part of Chaco, Corrientes, Salta and Tucuman), Bolivia (Beni and Pando), Brazil (where it is one of the commonest species, known to occur in the states of Amazonas, Bahia, Goias, Guanabara, Maranhao, Mato Grosso, ]Minas Gerais, Para, Pernambuco, Rio Grande do Sul, Santa Catarina and Sao Paulo), Guianas (British, Dutch and French), Colombia (Bolivar, Caqueta, Cauca, Cordoba, Cundinamarca, JMagdalena, ]Meta and Del Valle), Ecuador, Paraguay, Peru (Cuzco, Huanuco, Loreto, and Parco), and Venezuela (Amazonas, Apure, Aragua, Anzoategui, Bolivar, Guarico, Aliranda, Monagas and Sucre).

Some references in the literature record H. hydnoides also from Asia and Africa. Leveille (1844: 195) hsted it from Java and Sumatra and later Hennings (1893b: 221; 1894: 31; 1895: 58) from Celebes Is. and N e w Guinea. I have not examined any collection from Asia; it is unlikely that H. hydnoides occurs in that area.

From Africa H. hydnoides was recorded by Hennings (1893a: 29; 1893c: 105; 1895: 58; 1900b: 322 I from different localities: Abyssinia (Gebel Gedem) on trunk of Acacia sp., Togo (Bismarkburg Station), Mauritius Is., Madagascar and Tanganyika (Usambara). From Natal, Union of South Africa, Trametes hydnoides was hsted by Fries (1848: 9) and Cheesman (1909: 410) reported also T hydnoides "thickly imbricate on fallen log of Ficus sp." from Victoria Falls. Patouillard (1928b: 16) recorded it from Madagascar and Castellani and Ciferri (1950: 29) recorded it from Eritrea. I have not examined any of the collections upon which these records were based but a few collections that I found in herbaria from Africa labelled a T. hydnoides are in m y opinion H. hirta f hystrix.