“Hygrocybe umbilicata is well characterized by its vivid red or scarlet red with umblicate pileus, white short decurrent distant lamellae, lemon yellow or orange yellow stipe, subglobose basidiospores, and presence of cheilocystidia. This waxcap fungus represents first generic report of Hygrocybe for Bangladesh so far. Based on ITS sequence analyses, H. umbilicata nests in a highly supported clade (90% ML BS, 0.96 PP); it is grouped together with H. cantharellus, H. lepida, H. turunda, H. caespitosa, H. melleofusca, H. sparifolia, and H. papillata (Fig. 1). All of those species are the members of subg. Pseudohygrocybe, sect. Coccineae, subsect. Squamulosae, and are morphologically characterized by their often brightly colored basidiomata ranging from yellow, orange, red, gray or brown with a dry to subviscid pileus that is sometimes hairy or squamulose, and a stipe that is always dry (Arnolds 1990, 1995; Bon 1990; Lodge et al. 2014). However, H. umbilicata is nominally clustered with H. sparifolia, H. griseobrunnea, H. caespitosa and H. melleofusca with moderate support (61% ML BS), but they are distinguished from the new species in having ellipsoid to ellipsoid oblong basidiospores, absence of cheilocystidia and generally duller colors (Cantrell and Lodge 2004; Wang et al. 2013; 2015). Furthermore, the Chinese species H. griseobrunnea and H. sparifolia both have trichoderm pileipellis (Wang et al. 2013; 2015); H. melleofusca, originally described from Puerto Rico, has honey yellow to medium yellow brown with perforated pileus (Lodge & Pegler 1990).
Hygrocybe caespitosa, a species originally described from the south eastern USA, has a clay to cinnamon-brown pileus and a yellowish to bright yellow context (Lodge and Pegler 1990; Cantrell and Lodge 2004).
Hygrocybe rubroalba Picciola, Battistin & Vizzini seems to be the closest species to H. umbilicata, and has almost the same coloration of basidiomata and white lamellae. However, the Brazilian species H. rubroalba has a thicker stipe up to 10 mm wide, more crowded lamellae, and ellipsoid-oblong to oblong basidiospores (Vizzini et al. 2015). Other morphologically similar taxa, including H. batistae Singer, and H. coccinea (Schaeff.) P. Kumm, can also be separated from H. umbilicata micro- morphology. Hygrocybe batistae, a species originally described from Brazil, has dimorphic basidiospores, a diverculate pileipellis, and caespitose habit (Lodge and Pegler 1990; Vizzini et al. 2015). Hygrocybe coccinea has entirely yellowish to red-orange with adnate lamellae and oblong to ellipsoid basidiospores (Boertmann 1995; Bessette et al. 2012).
Considering the shape and the presence of cheilocystidia in Hygrocybe, the new taxon seems similar to H. rubida Vrinda & Pradeep. However, H. rubida, also a species of subsect. Squamulosae, originally reported from India, differs from H. umbilicata in its deep red stipe, and ovoid to subamygdaliform basidiospores (Vrinda et al. 2013).” (Hosen et al., 2016)
Hosen, Md Iqbal, et al. “Hygrocybe umbilicata sp. nov., with first generic report for Bangladesh and its phylogenetic placement.” Phytotaxa 280.1 (2016): 70-76. http://www.biotaxa.org/...