The first ITS phylogeny of the genus Cantharocybe (Agaricales, Hygrophoraceae) with a new record of C. virosa from Bangladesh

Md Iqbal Hosen,Tai-Hui Li,Deborah Jean Lodge,Alan Rockefeller

doi:10.3897/mycokeys.14.9859

Abstract

This is the first internal transcribed spacer (ITS) phylogeny of the enigmatic genus Cantharocybe and includes ITS sequences from two out of the three holotype collections. Two species are reported from the Americas and only a single species from Asia. Additionally, a collection of Cantharocybe virosa collected from tropical Bangladesh was included in this study. This species is a new record for Bangladesh, and is characterized by its tawny gray or grayish brown pileus and stipe surface, smooth ellipsoid basidiospores, elongated necked lecythiform cystidia, a trichoderm pileipellis, and abundant clamp connections. Molecular phylogenetic analysis using ITS, and combined analyses of ITS with the large subunit of nuclear ribosomal RNA (nrLSU) showed that the collection from Bangladesh is conspecific with the Indian C. virosa. A large, previously unknown intron was found in the ITS of C. brunneovelutina and C. virosa, while the C. gruberi sequence was found to be truncated where the intron would have been inserted. The intron was not identical between Cantharocybe species, and may be phylogenetically informative. Morphological description, color photographs and line drawings are provided for Bangladesh collection C. virosa. A key to the genus Cantharocybe is provided.

Highlights

The genus Cantharocybe was introduced by Bigelow and Smith in 1973 to accommodate Clitocybe gruberi Smith, based on the large yellow basidiomata, oblong to subcylindrical to elongated basidiospores and the presence of lageniform to lecythiform cheilocystidia
The Bangladeshi C. virosa is characterized by its gray to grayish brown basidiomata, moderately crowded lamellae, fine squamules on stipe surface formed from clusters of lecythiform caulocystidia, ellipsoid to broadly ellipsoid basidiospores, and a trichoderm pileipellis
The Bangladeshi collection has a grayish brown to dark brown pileus, cheilocystida with short neck up to 15 μm long, and clearly defined trichoderm pileipellis

Summary

Introduction

The genus Cantharocybe was introduced by Bigelow and Smith in 1973 to accommodate Clitocybe gruberi Smith, based on the large yellow basidiomata, oblong to subcylindrical to elongated basidiospores and the presence of lageniform to lecythiform cheilocystidia. Other taxa in this genus do not have large-sized yellow basidiomata and oblong to elongated basidiospores. Lodge et al (2014) extended the generic circumscription of the genus to include taxa with large, clitocyboid, yellow, dark brown to brownish gray basidiomata with long decurrent or adnate with decurrent tooth lamellae; abundant cheilocystidia which are usually lecythiform, sometimes with a mucronate apex, with or without a rounded capitulum; smooth, inamyloid, oblong, elongate, ellipsoid to broadly ellipsoid or rarely subglobose, basidiospores; a trichoderm or cutis pileipellis; and caulocystidia similar to cheilocystidia. Recent molecular phylogenetic studies show that Cantharocybe is at the base of the hygrophoroid clade and is sister to Ampulloclitocybe (Pers.) Redhead, Lutzoni, Moncalvo & Vilgalys, but it is not clear if Cantharocybe and Cuphophyllus Donk (Bon) are members of Hygrophoraceae s.s. (Matheny et al 2006, Binder et al 2010, Lodge et al 2014)

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