Hericium rajchenbergii is currently known to grow exclusively on dead and/or living standing trunks of Lithraea molleoides (Anacardiaceae) in the subxerophytic Mountain Chaco Forests (“Bosque Serrano”) of in the Sierras Chicas of Córdoba province central Argentina, in an altitudinal range from 600 to 1400 m a.s.l. There are only 4 specimens recorded, even with extensive surveys in the area. Total population size is estimated at no more than 500 mature individuals. The species is estimated to have had a population decline of 80-90% in the last 50 years, due to habitat loss. The forests where the species lives are extremely endangered, and more than 90% has been lost between 1969 and 1999 (Zack et al 2004, Atala et al 2009). This decline is still ongoing, mainly due to loss of its host to logging and fire. As such it is assessed as critically endangered.
Hericium rajchenbergii Robledo & Hallenberg was described from Córdoba Mountains, Central Argentina (Hallenberg et al. 2012). The species has no synonyms. It represents an independent lineage related to Hericium coralloides (Scop.) Pers. and Hericium novae-zelandiae (Colenso) Chr.A. Sm. & J.A. Cooper.
Hericium rajchenbergii is a native species presents in the subxerophytic montane chaco forests “Bosque Serrano” of central Argentina. This species is associated to mature individuals of Lithraea molleoides (Vell.) Engl. (Anacardiaceae) in a range from 600 to 1400 m a.s.l. forests patches of Bosque serrano in Córdoba province. These forests fragment are extremely endangered, more than 90% have been lost between 1969 and 1999 (Zack et al 2004, Atala et al 2009).
Hericium rajchenbergii is known from only four specimens growing exclusively on dead and/or living standing trunks of Lithraea molleoides (Anacardiaceae) in the subxerophytic Mountain Chaco Forests (“Bosque Serrano”) in the Sierras Chicas of Córdoba province of central Argentina, in an altitudinal range from 600 to 1400 m a.s.l. Despite its host being widespread throughout central South America, H. rajchenbergii is likely endemic to the Mountain Chaco Forests of central Argentina.
To date the species is known only from the Cordoba region, Central Argentina. It has only been found associated with Lithraea molleoides in the Bosque Serrano in the Sierras Chicas and Sierra Grande mountains, at an altitudinal range between 600-1400m. The particular type of forests where the species grows extends from Cordoba mountains in central Argentina to the north, in a thin strip of intermittent patches reaching southern Bolivia. The species is expected to be found throughout this habitat, although it has not been reported outside Cordoba and San Luis provinces even after extensive search. There are an estimated 50 sites, each site with up to 10 mature individuals. Total population size is estimated at no more than 500 mature individuals. The species is estimated to have had a population decline of 80-90% over the last 50 years due to habitat loss. These forest fragments are extremely endangered, and more than 90% of its area was lost between 1969 and 1999 (Zack et al 2004, Atala et al 2009). This decline is still ongoing, mainly due to loss of its host to logging and fire.
Population Trend: Decreasing
Hericium rajchenbergii is an obligate parasite of Lithraea molleoides. So far it has only been found in the Mountain Chaco Forests of Cordoba mountains (in a range from 600 to 1400 m a.s.l.), despite its host being widespread throughout central South America. It likely occurs along the distribution of its host in the Mountain Chaco Forests from Córdoba to Bolivia. The species has only been collected in late autumn, with cold and humid weather. It has been recorded on or near the same date in different years.
The species is strongly threatened by deforestation of the Mountain Chaco Forests. These forest fragments are extremely endangered, and more than 90% of its area was lost between 1969 and 1999 (Zack et al 2004, Atala et al 2009). The host tree was one of the dominant trees of the ecosystem (Cabido & Zak 1999). Traditionally the wood of L. molleoides has been used as firewood, and it has been stated as “in regression” (Atala et al 2009). Mature trees of the species are now much less common. In 2009, the Mountain Chaco Forests covered 2,334,712 ha in Cordoba, of which only 8.25% (193,689 ha) correspond to dense or mature forest, as the rest has been degraded to open forests, shrublands and grasslands (Atala et al 2009). During the last 10 years, intentional forest fires, as well as the advance of the agricultural frontier and urbanization have continued on an increasing scale. In addition, the exotic invasive tree, glossy privet (Ligustrum lucidum), has increased 50 times (from 50 to 2500 ha) (Gavier-Pizarro et al 2012).
The main action to prevent the decline of the species is the protection of its habitat. A survey of presence and abundance of the species in the existing Protected Natural Areas that includes “Bosque Serrano” is needed as well as enforcement of public policies aimed at recovering secondary forests and supporting existing “forests restoration programs” organized by local NGOs. The surveys will allow decisions to be made about the creation of new conservation areas, as well as the reintroduction of the species in protected areas where it is not present or occurs in low abundance. As the species is able to be grown in culture, the production of basidiomata ex-situ is being investigated (Terzzoli et al, unpublished data). This may enable the reintroduction of the species.
Determine the distribution of the species is needed, both documenting its precise distribution in areas where its presence is known (Sierras de Córdoba), as well as documenting its presence within its potential distribution throughout its host range. As other Hericium species, H. rajchenbergii is edible (Gerardo Robledo pers. experience). The chemical and nutritional compositions of basidiomata are being studied (Rodríguez et al, unpublished data) and will be compared with other Hericium species.
The species is able to be grown in culture and the production of basidiomata ex-situ is being investigated (Terzzoli et al, unpublished data). The development of production techniques will have a direct impact on reducing future extraction pressure.
The species is not currently consumed or commercialized, and until now it has not been included in the National Alimentary Code. However, it has potential as wild edible species, and its nutritional characteristics are being described.
Atala D.; Baudo F.; Álvarez Igarzabal M.A.; Fernández F.; Medina A. M.; Miatello R.A. & Sonzini B. 2009. Proceso y Programa de Ordenamiento Territorial de los Bosques Nativos de la Provincia de Córdoba. Módulo de Gestión Ambiental Sierras y Pampas de Altura. Secretaria de Ambiente de la Provincia de Córdoba. Córdoba, Argentina. p. 202.
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Nils Hallenberg, R. Henrik Nilsson & Gerardo Robledo. 2013. Species complexes in Hericium (Russulales, Agaricomycota) and a new species - Hericium rajchenbergii - from southern South America. Mycological Progress 12 (2): 413-420. DOI 10.1007/s11557-012-0848-4.
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