Species richness, taxonomy and peculiarities of the neotropical rust fungi: are they more diverse in the Neotropics?

Abstract

The species richness of rust fungi (Pucciniales or Uredinales) in the neotropics is reviewed. Species numbers are presented for all neotropical countries and rust-plantratios calculated. It is discussed whether the ratio for a given region can be explained by the species richness of vascular plants alone or whether it is caused by additional factors. In the first case, ratios should apply globally and vary only slightly; in the second case, more diverging ratios are expected. Observed ratios ranged between 1:16 and 1:124 in the neotropics. The large differences are certainly influenced by unequal levels of investigation, rendering interpretation difficult. Differences seem also to be influenced by the taxonomic composition of floras regarding the percentage of host families or genera bearing different numbers of rust species. This indicates that rust species richness is not driven solely by plant species richness. Ratios calculated for Switzerland, Austria and Japan are distinctly higher than for the neotropics indicating that certain temperate regions are proportionally richer in rust fungi than the neotropics. Uredinial states and short-cycled rust species prevail in the neotropics. The preponderance of uredinial states may be due to the heterogeneous spatial composition of certain vegetation types in the wet tropics. Shortcycled rusts may be adapted to a pronounced seasonality that can be encountered in many drier neotropical biomes. Future research needs to fill our knowledge gaps on the taxonomy and ecology of neotropical rust fungi are discussed.

Riqueza de fungos causadores de ferrugens em plantas hospedeiras da Região Metropolitana de Belém, PA, Brasil

“…A flora dos remanescentes florestais da RMB foi considerada por Amaral et al (2009) de alta riqueza de espécies endêmicas, mas Berndt (2012) argumenta que a riqueza de espécies de ferrugem não é impulsionada unicamente pela riqueza de espécies de plantas, mas sim pela composição da flora, em relação à porcentagem de famílias e gêneros de plantas hospedeiras de diferentes espécies de ferrugens. Isso pode explicar a menor riqueza de fungos no PEUTi, onde a riqueza de hospedeiras foi menor também em relação à EMBRAPA.…”

“…Essas Famílias também constam como as mais ricas em hospedeiros em vários estudos nos diferentes continentes (Berndt 2012). Para o Bioma Amazônia, Sotão et al (2009) e França et al (2010 em estudos realizados no Pará e no Amapá, respectivamente, registraram estas famílias entre as mais representadas em número de ferrugens,e a família Bignoniaceae entre as de maior riqueza de ferrugem para a região Norte.…”

“…No Neotrópico, o Brasil é considerado o país mais diverso e melhor estudado quanto aos fungos Pucciniales (Salazar-Yepes & Carvalho Jr. 2010, Berndt 2012. Dados copilados por Hennen et al (2005) e Carvalho Jr. & Sotão (2010, com base em material depositado em herbários ou citados em literatura, registram cerca de 750 espécies e 66 gêneros desta Ordem para o país, das quais 184 são conhecidas para a região Norte e entre estas, 66 espécies e 3 gêneros tem distribuição exclusiva para esta região.…”

Tropical fungal diversity: closing the gap between species estimates and species discovery

“…Whether these ratios hold up in tropical regions is indirectly assessed in the papers of Berndt (2012) and Mangelsdorff et al (2012) with sometimes conflicting results, highlighting the value of both sound taxonomic and monographic treatments as well as the need for more long-term fungal studies in tropical regions. For instance, the rust fungi (obligate plant pathogens) may be the best documented group of microfungi, yet Berndt (2012) found that ratios of known rust:plant species in Neotropical countries ranged from 1:16 to 1:124-no doubt a reflection, at least in part, of under sampling for fungi in most of these areas.…”

“…Just as the study of Berndt (2012) shows that species data is unevenly distributed geographically, other papers in this issue show that there are, likewise, a number of specialized habitats that still remain to be fully assessed for tropical fungal diversity. These include fungi inhabiting insect guts, among which are Trichomycetes that have been reviewed by Lichtwardt (2012).…”