Xanthagaricus pakistanicus sp. nov. (Agaricaceae): first report of the genus from Pakistan

Abstract

Xanthagaricus pakistanicus is described as a new species from lowland northern Pakistan, based on morphological and molecular data. It is characterized by a yellowish pileus, covered with dark brown squamules, a stipe with yellowish fibrils, globose basidiospores, and pileal squamules made up of pseudoparenchymatous epithelium with encrusted walls. Molecular phylogenetic trees were inferred based on nucleotide sequences of the internal transcribed spacer (ITS1-5.8S-ITS2) region and 28S nuclear ribosomal DNA. In phylogenetic analyses the genus Hymenagaricus sensu lato (s. l.) was inferred as a nonmonophyletic group and recovered in two monophyletic clades, consisting of species of the genera Xanthagaricus and Hymenagaricus sensu stricto (s. str.). On account of the pileal squamule structure (pseudoparenchymatous epithelium) and yellowish basidiospores, and the phylogenetic position in the Xanthagaricus clade the new species X. pakistanicus belongs to the genus Xanthagaricus. Morphoanatomical comparison with the known species of Xanthagaricus is provided. We also made six new combinations in Xanthagaricus: X. calicutensis, X. epipastus, X. ochraceoluteus, X. rufomarginatus, X. subaeruginosus, and X. taiwanensis. With this study the number of known species in the genus Xanthagaricus increases to 19.

Two new species of Xanthagaricus and some notes on Heinemannomyces from Asia

“…However, morphologically, X. pakistanicus has a light orange-yellow to moderate orange-yellow pileus, and globose to subglobose basidiospores measuring 7–7.5 × 6.5–7.0 µm ( Hussain et al 2017 ).…”

“…A total of 52 sequences (36 for ITS and 16 for 28S, Table 1 ) of Agaricaceae was retrieved from GenBank based on NCBI blast search results and recent publications ( Ge et al 2008 , Vellinga et al 2011 , Ge and Yang 2017 , Hosen et al 2017 , Hussain et al 2017 ), and then combined with the newly generated ITS and 28S sequences of Clarkeinda trachodes (Berk.) Singer, Xanthagaricus and Heinemannomyces .…”

“…Species in the genus Xanthagaricus are saprotrophic, and mainly distributed in Asia and South Africa. For instance, 11 species from India ( Heinemann and Little Flower 1984 , Little Flower et al 1997 ), four species from Sri Lanka ( Heinemann and Little Flower 1984 , Pegler 1986 , Little Flower et al 1997 ), two species from Africa ( Reid and Eicker 1995 , 1998 ), one species each from mainland China ( Hosen et al 2017 ), Pakistan ( Hussain et al 2017 ), and Taiwan, China ( Ge et al 2008 ) have so far been validly reported. However, Asia has more than the currently known species of Xanthagaricus , as sequences of several species of this genus are available in GenBank, especially from Thailand and Malaysia.…”

“…Index Fungorum ( http://www.indexfungorum.org/Names/Names.asp ) lists 12 taxa of Xanthagaricus . However, a recent study by Hussain et al (2017) has transferred six species to Xanthagaricus from Hymenagaricus .…”

“…Song ( Hosen et al 2017 ) and X. pakistanicus Hussain, Afshan & Ahmed ( Hussain et al 2017 ), the number of known species of this genus increases to 22.…”