Phellinus artemisiae Vlasák & Vlasák Jr., 2017

Vlasák, Josef & Vlasák, Josef, 2017, Phellinus artemisiae sp. nov. (Basidiomycota, Hymenochaetaceae), from western USA, Phytotaxa 303 (1), pp. 93-96 : 93-96

Phellinus artemisiae Vlasák & Vlasák Jr. , sp. nov. ( Figs. 1–3)

Mycobank MB 819360

Dignosis: — Basidiocarps perennial, effused-reflexed, 3–5 cm in diam., growing on living Artemisia tridentata in western USA. Pileus rimose and pore surface cracked with age, pores rather large, angular, 3–4 per mm. Setae7–10 × 13–28 μm, basidiospores broadly ellipsoid to subglobose, hyaline, smooth, negative in Melzer´s reagent, 4–5 × 3–4 μm. Unique sequence of ribosomal ITS and LSU genes.

Etymology: — Artemisiae (Lat.) : referring to the host genus Artemisia .

Type: — USA. California: San Diego Co., Pine Valley, along Pine Valley Creek, 32.834, -116.546, on living Artemisia tridentata , 13 Mar 2016, J. Vlasák Jr. 1603/1- J ( PRM 944505, GenBank KY 230518).

Basidiocarps perennial, effused-reflexed, projecting up to 3 cm, 5 cm wide and 1.5 cm thick at base, triangular in longitudinal section with the upper surface and pore surface at angles of about 60 degrees from the horizontal axis; upper surface pale greyish brown near the margin, finely tomentose, in older parts blackish brown, indurated but without a true crust or cuticle, strikingly rimose; pore surface brown at first, dark grayish brown later, with deep fissures with age or after drying; the pores angular, 3–4 per mm, on sloping surface elongated up to 2 mm, dissepiments thin; context dark reddish brown, woody hard, up to 2 mm thick; tube layers stratified, each layer up to 5 mm thick.

Hyphal system dimitic, generative hyphae simple-septate, pale yellowish to almost hyaline, thin-walled, 2–3 μm in diam., skeletal hyphae yellowish to light brown, slightly thickened walls with a wide lumen, 3–4 μm in diam, tramal hyphae parallel along tubes.

Setae rare to locally abundant, brown in KOH, distinctly thick-walled (up to 3 μm), broadly ventricose to ovoid with abrupt sharp point, 13–28 × 7–10 μm.

Basidia broadly ovoid, 4-sterigmate, 10–12 × 6–8 μm, simple-septate at the base.

Basidiospores broadly ellipsoid to subglobose, hyaline, smooth, negative in Melzer´s reagent, with somewhat thickened wall, distinctly apiculate, 4–5(6) × 3–4 μm.

Type of rot — white rot on Artemisia tridentata living woody stems.

Additional specimens examined — USA. California; San Diego Co., Pine Valley , on living Artemisia tridentata , 13 Mar 2016, J. Vlasák Jr. 1603/4- J ( JV), 1603/5- J ( JV) .

Comments —The species is not rare at the locality as we noted several basidiocarps in just one day, both around Pine Valley and also further south-east where the Pacific Rim Trail crosses I-8 highway. On casual inspection, the species reminds of Pyrofomes sp. or dark Perenniporia sp. rather than Phellinus , because of large, somewhat irregular pores, rimose surface and the absence of pileus crust. Phellinus arctostaphyli (Long) Niemelä grows in the same locality is very different from P.artemisiae by having mostly horizontal pore surface, small and round pores (5–6 per mm) and a distinct crust. Also, it never grows on Artemisia . Phellinus spp. on living plants are often specialized to certain plant species ( Cui et al. 2015) and we believe that it so also the case of P. artemisiae . Artemisia sp. ( Asteraceae ) is a strikingly unique substrate for Phellinus ; from the 240 different Phellinus hosts listed in the synopsis of Larsen and Cobb-Poulle (1990) none belongs to the Asteraceae family.

The ITS and LSU sequences of Phellinus artemisiae (GenBank KY230518) are not much related to any taxa in GenBank, showing only rather distant relationships to Phellinus mori Y.C. Dai & B.K. Cui , a resupinate species growing on living Morus trees in China, with similar spores and also cracked basidiocarps ( Dai et al. 2008). LSU sequence alone is also most similar to P. mori (percentage and number of nucleotide identities are 98%; 860/877) and next to Phellinus spiculosus (Campb. & Davids.) Niem. (97%; 857/877). Inonotus henanensis Juan Li & Y.C. Dai has resupinate and cracked hymenophore and is more or less similar to P.artemisiae in macro-morphology, but it has a monomitic hyphae and bigger basidiospores 5.5–6.5 × 4.5–5.7 μm ( Li et al. 2007).

ITS1 sequence of P. artemisiae contains a remarkable, 30b microsatellite (GT) 6 (AT) 5 AC(AT) 3 that is present in many mammalian genomes but not in fungi (BLAST search in GenBank, Nov 2016).