Leptographium sinoprocerumsp. nov., an undescribed species associated withPinus tabuliformis-Dendroctonus valensin northern China

Abstract

During a study of ophiostomatoid fungi associated with the invasive pest Dendroctonus valens in the Pinus tabuliformis ecosystem in northern China, a multigenic (ITS2-LSU, beta-tubulin and EF1-alpha) phylogenetic analysis and examination of morphological features revealed in addition to Leptographium procerum the occurrence of an undescribed species. The new species, Leptographium sinoprocerum, belongs to the L. procerum-L. profanum clade. Both L. procerum and L. sinoprocerum are similar to each other and occur sympatrically in the ecosystem studied. Nevertheless L. sinoprocerum can be distinguished from L. procerum by shorter conidiophore stipes arising from both submerged and aerial hyphae, slightly more oblong conidia, a granular ornamentation on the submerged hyphae and dark olivaceous colonies on MEA.

Taxonomy and phylogeny of the Leptographium procerum complex, including Leptographium sinense sp. nov. and Leptographium longiconidiophorum sp. nov.

“…* Hosts, vectors and origin from studies where the identity of L. procerum was confirmed based on DNA sequences (Jacobs et al 2004;Jankowiak 2012;Jankowiak and Bilański 2013a, b, c;Jankowiak and Kolařík 2010;Kim et al 2005;Lu et al 2008Lu et al , 2009aLinnakoski et al 2012; and from the present study). All unmarked hosts and vectors were listed by Jacobs and Wingfield (2001), but identifications were based on morphology only.…”

“…Pathogenicity trials conducted in China on P. tabuliformis suggested that the fungus might be more pathogenic to pines in that country than in its native range in North America (Lu et al 2010;Sun et al 2013). The identity of L. procerum in China has been confirmed using DNA sequence analyses, which also confirmed its relatedness to several other species in the genus (Lu et al 2008;2009a, b;Taerum et al 2013). In another study, Duong et al (2013) characterized the mating type genes of L. procerum and its close relative, L. profanum, showing that both species are heterothallic.…”

“…In 2008, L. procerum was reported for the first time from China as an associate of the red turpentine beetle Dendroctonus valens (Lu et al 2008), which is thought to have been introduced into that country from North America (Cognato et al 2005). In northern China this beetle-fungus combination has contributed to the mortality of more than a half million hectares of native pine forests (Miao et al 2001;Sun et al 2013).…”

“…Interestingly, apart from L. procerum (Kendrick 1962) and L. profanum described from USA, and L. sibiricum from Russia (Jacobs et al 2000), all other species in the complex have been described from East Asia (Linnakoski et al 2012). Leptographium pinidensiflorae was described from Japan (Masuya et al 2000), L. bhutanense from Bhutan , and L. sinoprocerum (Lu et al 2008), L. gracile and L. latens (Paciura et al 2010) from China.…”

“…The three gene regions, the internal transcribed spacer region 2 and partial large subunit of the 2 ribosomal DNA (ITS2-LSU), b-tubulin (bT) and translation elongation factor-1 alpha , that have typically been used for species delineation in Leptographium during the past decade, have also been used to identify L. procerum from China (Lu et al 2008;2009a, b;Taerum et al 2013) as well as some of the new species in the complex. However, Paciura et al (2010) and Linnakoski et al (2012) showed that the ITS2-LSU and bT gene regions have limitations in distinguishing closely related species in the L. procerum complex.…”