Gyrodontium sacchari ( Spreng . : Fr . ) Hjortstam ( Boletales , Basidiomycota ) in America : New records and its geographic distribution

Gyrodontium sacchari (Spreng.: Fr.) Hjortstam is reported from two new areas of northwest and northeast Argentina, Brazil, and French Guiana. A geographic distribution map of the species in America and a discussion on its pattern of distribution are presented. DOI: 10.15560/10.6.1514

The distribution of G. sacchari in America is based on a limited number of published records spread over the literature that are summarized in Table 1.Besides Guadeloupe, the type locality, the species is known from Cuba, Brazil, French Guiana, Argentina, and Ecuador (Maas Geesteranus 1966;Bononi 1988;Hjortstam 1995;Carlier et al. 2004;Wright and Wright 2005;Laessøe and Petersen 2008).Recently, it was reported from Mexico (Valenzuela et al. 2012), the northernmost record for the taxon.
In this work we report three new records for the species from northern Argentina and one from northeastern Brazil.We present a geographic distribution map of the species with a discussion of its distribution pattern.
The first record of G. sacchari in Argentina was published Gyrodontium sacchari (Spreng.: Fr.) Hjortstam (Boletales, Basidiomycota) in America: New records and its geographic distribution hole of a dead fallen log of an undetermined hardwood (Figure 2A), in the locality of Tujubeba (10°56′04.3″S, 37°11′12.2″W), São Cristóvão, Sergipe state.This area contains remnants of Atlantic Rain Forest in the Brazilian coastal plains.Even though the material could not be properly conditioned to be kept as voucher specimen, we have the photographic record (Figure 2A).On a return trip to that place to find the specimen again, we found a dam instead (Figure 2B).
Based on all records available in the literature (Table 1), we present a preliminary distribution map of G. sacchari in America (Figure 4).Included are two records from Costa Rica and Belize, where the species is purported present based on herbarium records available at the virtual online herbaria K and NY.These herbarium specimens were identified by experienced mycologists (Table 1) and, although we did not study these materials and confirm their identity, we included them because they constitute evidence and possible hypothesis of the species distribution.
Gyrodontium sacchari seems to be distributed throughout Central America and the Caribbean region as well as northern coastal areas of South America (circled area in Figure 4).From this central area, the species appears to have spread northward and southward reaching subtropical areas in both hemispheres (as indicated by arrows in Figure 4).The presence in Northern Mexico was recently reported from Sierra de Álamos, Río Cuchujaqui Biosphere Reserve, which is region with diverse ecosystems including xerophilous scrub, tropical deciduous forest and oak-pine forest (Valenzuela et al. 2012).However, there is no information on the ecosystem and/or substrate on which G. sacchari was collected, except for altitude, 425 m a.s.l., making it difficult to explain this occurrence in its distribution.
Regarding the distribution in South America, G. sacchari spans over the Atlantic Rain Forest reaching northeast Argentina to the south.The southernmost limit of distribution seems to be at 30°S near Porto Alegre (Guaiba locality, Table 1).Probably, G. sacchari continues to the north connecting with the central distribution area, either along the coast or through the islands and remnants of Atlantic forest occurring in the Caatinga (blue arrow with "?" in Figure 4), but records are needed to confirm this hypothesis.The new record in the Argentine Yungas is not surprising considering the presence of the species in Ecuador.Yungas forests are characterized by the presence of particular floristic elements of different origins and constitute an Andean corridor for several fungal species [see Robledo and Rajchenberg (2007) for a discussion].Gyrodontium sacchari could follow this corridor, as previously shown for other species (Robledo et al. 2006;Amalfi et al. 2014).Future collecting could reveal the presence of G. sacchari along the distribution of Yungas forest in Bolivia, Peru, Colombia, and Venezuela.Alternatively, its distribution following the Atlantic Rain Forests and Yungas forest (blue arrows in Figure 4) might suggests NSDF (Neotropical Seasonal Dry Forests) (Prado 2000;Pennington et al. 2000) as a possible explanation of the distributional pattern; in which case, the species should be present in some intermediate areas in Paraguay.This idea has been previously suggested as a way to understand distributions of other fungal species by Romero et al. (2012).The present distribution of G. sacchari illustrated in Figure 4 may not represent its actual distribution in America, but possibly reflects areas of intense collecting efforts.Despite sampling effort being far from enough in South America, the relatively few records throughout the distribution area could, in fact, reflect a more restricted distribution pattern.
Based on our field experience, it appears that basidiomata are produced irregularly and/or they are ephemeral.For example, after about 10 years of field work in French Guiana, CD found only two specimens.In the last 4 years, walking repeatedly along the same path in the Nouragues Natural Reserve, only once we encountered basidiomata of G. sacchari on a big living tree by the side of the track [French Guiana, Municipality of Regina, Réserve Naturelle des Nouragues, CNRS Inselberg station, track (layon) C.I., on the way to the Nouragues inselberg, trunk of living tree, unidentified angiosperm, 120 m a.s.l., July 2012, Decock MUCL 54404] (Figure 3A-B).Basidiomata were not observed along the path the year before; and checking the same tree yearly for another two years, basidiomata were no longer observed.The species may require specific ecological conditions to produce basidiomata.
Considering the local conditions where the species had been collected, it could be predicted that the species would be expected in other areas of similar conditions, though endemism also exists at local scale.In the case of G. sacchari, considering its wide distribution through the Neotropics, its mycelia might be potentially present everywhere (where the environmental conditions in a broad sense exist), while fructifications are more unpredictable.
The species is mostly found inside the hollowed out heartwood of decaying dead tree trunks.This may be one of the reasons why the species has been overlooked.However, as previously mentioned, it has also been reported on living trees.It is interesting to note that the type collection is the only record on leaves of sugar cane (Saccharum officinarum L.), a monocotyledonous plant.We can infer that it was growing on a pile of leaves and bagasse waste, and not over leaves of standing plants.It was also found on a wooden pole from a stilt house in a human made environment in French Guiana.
Finally, it cannot be excluded that "cryptic" species are involved.At a global scale G. sacchari has been reported from a wide range of substrates and ecosystems, e.g., on living Pinus sp. in Italy (Bernicchia et al. 2007) and trunks of Pinus luchuensis Mayr. in Bonin Islands (Sato et al. 2010).It has been shown that a large number of cryptic species occur in Coniophora DC. (a phylogenetic sister clade of Gyrodontium), that were not detected based on morphological characters (Kauserud el al. 2007).A similar situation could occur with Gyrodontium in South America, which has a wide distribution encompassing varied ecological systems, e.g., Caribbean, Atlantic Rain forest, Andean corridor.

Figure 1 .
Figure 1.A-D.Macroscopical features of Gyrodontium sacchari (EM Giorgio 20 CORD).A) Detail of the pilear surface.B) General view in situ.C) Detail of the hymenial surface.D) General view of hymenial surface.Photos by E. M. Giorgio.

Figure 4 .
Figure 4. Distribution map of Gyrodontium sacchari based on records from Table 1.Main Eco-regions of America are shown.Shaded area indicates the main distribution in Central America.Arrows indicate potential distribution routes, see discussion in the text.

Figure 3 .
Figure 3. A-B.Macroscopical features and habitat of Gyrodontium sacchari recorded in French Guiana (MUCL 54404.A) General view in situ, note the brownish spore print in the pilear surface.B) Close up of the hymenophore, showing the white sterile margin.Photos by C. Decock.

Figure 2 .
Figure 2. A-B.Macroscopical features and habitat of Gyrodontium sacchari recorded in Sergipe Brazil.A) Close up of the basidiome in situ, showing the typical hymenophore and the brownish spore print in the pilear surface.B) Area of previous record, where a dam is under construction today.Photos by C. Franco.

Table 1 .
Thiers (2014)rds of G. sacchari on which the geographic distribution map is based.Herbarium acronyms are according toThiers (2014).