Over the past fifteen years, there has been an increase in commercial harvesting. Such harvesting may be unsustainable. Quantities harvested have declined in areas where livestock have been concentrated, suggesting that some land use practices introduced by Europeans (this could be termed habitat destruction) may conflict with the sustainability of truffle populations

AFRICA: Botswana; Namibia; South Africa.

Over 20 records from scientific sources (specimens, databases and bibliographic sources combined, excluding duplicates) from at least 1895 to 2008, with observations in March, April, May, June and July. Most of the evidence used in the present study derives from collections or market purchases for scientific study. There is almost no information currently available from rural collector-suppliers, or from their commercial buyers about geographical distribution and abundance. Over the past fifteen years, there has been an increase in commercial harvesting. Such harvesting may be unsustainable. Quantities harvested have declined in areas where livestock have been concentrated, suggesting that some land use practices introduced by Europeans (this could be termed habitat destruction) may conflict with the sustainability of truffle populations.

Desert truffles, as mycorrhizal fungi, play an important role in enabling plants to grow in extreme and highly marginal environments. For centuries, this species has been collected for food as part of a hunter-gatherer subsistence way of life by men and women of the Khoisan people (also known as Bushmen or San) of the Kalahari Desert. The fungus is also sometimes sold at the roadside by local people. In the last fifteen years, commercial harvesting of fruitbodies has also increased, and there are now several Internet sites offering them for sale at an international level (TRAPPE ET AL., 2008). Concern has been expressed about the dangers of unsustainable exploitation, and a debate has been started in respect of the need to ensure that the indigenous Khoisan people are the primary beneficiaries of any commercial development (MSHIGENI ET AL., 2005). The fungus is used in traditional Khoisan medicine as an antidote to some poisons (TRAPPE ET AL., 2008), but no scientific investigations of potential medicinal benefits from this fungus were found during the preparation of this work. It has been cited in a patent application as an optional ingredient of a cosmetic preparation (GOLZ-BERNER & ZASTROW, 2005).

Native to arid savannah of the Kalahari Desert in southern Africa.

Associated with many different and varied organisms. Animalia. Hyaena brunnea Thunberg; Otocyon megalotis (Desmarest, 1822); Papio ursinus (Kerr, 1792); Suricata suricatta (Schreber, 1776). Monera. Bacteria indet. Plantae. Acacia hebeclada DC., A. mellifera (M. Vahl) Benth., A. uncinata Lindl.; Aristida sp.; Citrullus lanatus (Thunb.) Matsum. & Nakai (mycorrhizal); Dichostachys cinerea Wight & Arn.; Enneapogon cenchroides (Licht. ex Roem. & Schult.) C.E. Hubb.; Eragrostis rigidior Pilg., Eragrostis sp.; Grewia flava DC.; Pennisetum glaucum (L.) R. Br. [as P. typhoides (Burm. f.) Stapf ex C.E. Hubb.]; Rhigozum brevispinosum Kuntze, R. trichotomum Burch.; Sorghum bicolor (L.) Moench; Stipagrostis uniplumus (Licht.) de Winter; Terminalia sericea Burch. ex DC.

Kalaharituber pfeilii has been shown to form a mycorrhizal association with Citrullus lanatus, and is probably also mycorrhizal with most if not all of the associated plants listed in the previous paragraph (TAYLOR ET AL., 1995). Various mammals have been observed to dig for and eat fruitbodies (TRAPPE ET AL., 2008). Various unidentified bacteria have been observed in association with ascomata of this species, and sequences of some of these have been deposited in the NCBI GenBank database [www.ncbi.nlm.nih.gov]. No records have been found of associations with other fungi, though they are likely to occur. This species is known only from southern African deserts, where it shows strong preference for compact and slightly calcareous sands ranging in pH from 5•5 to 7•2 (TAYLOR ET AL., 1995). TRAPPE ET AL. (2008) note that, although precise information is not available, there is general agreement that a certain minimum amount of precipitation must occur in any given year if this species is to produce ascomata.

Over the past fifteen years, there has been an increase in commercial harvesting of K. pfeilii. Such harvesting may be unsustainable (J. TAYLOR, pers.comm.). Quantities harvested have declined in areas where livestock have been concentrated, suggesting that some land use practices introduced by Europeans (this could be termed habitat destruction) may conflict with the sustainability of truffle populations (TAYLOR ET AL., 1995; TRAPPE ET AL., 2008). Living in an arid environment, this species is adapted to survive at levels of heat and water stress which would be very unfavourable for other fungi. As a result, it already lives in conditions near the limit for sustainable life. Climate change and global warming in particular are thus likely to be significant long-term threats. No threats from pollution have been noted.

Using IUCN Categories & Criteria, evaluated as vulnerable by MINTER (2013).

Awareness of the importance of this desert truffle is very low even at governmental level: a survey of the most recent relevant national action plans and reports for the Rio Convention on Biological Diversity [www.cbd.int/nbsap/search/default.shtml, accessed 4 October 2013] by Botswana, Namibia and South Africa (the three countries from which Kalaharituber has been recorded) showed that none had any conservation plans for these fungi, and only Botswana recognized that there might be a problem of over-exploitation. The appropriate authorities in each of the three countries where it occurs should be made aware that there are important conservation issues regarding this fungus.

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