Ophiocordyceps borealis L.S. Zha & P. Chomnunti, 2021

Zha, Ling-Sheng, Kryukov, Vadim Yu, Ding, Jian-Hua, Jeewon, Rajesh & Chomnunti, Putarak, 2021, Novel taxa and species diversity of Cordyceps sensu lato (Hypocreales, Ascomycota) developing on wireworms (Elateroidea and Tenebrionoidea, Coleoptera), MycoKeys 78, pp. 79-117 : 79

Ophiocordyceps borealis L.S. Zha & P. Chomnunti sp. nov. Fig. 2

Etymology.

Referring to the region (south of boreal zone of the Russian Far East) from where the species was collected.

Sexual morph.

Parasitising Elateroidea larvae ( Coleoptera ) living in fallen wood. The larvae are cylindrical, 11 mm long and 1.1-1.3 mm thick, yellowish-brown; their body cavity stuffed with milky yellow mycelia and their intersegmental membranes covered with many milky yellow and flocculent funiculi. Stromata arising from any part of larval body, single or paired, unbranched. Stipe grey, slender and cylindrical, fibrous and flexible, curved more or less, 10-13 mm long and 0.25-0.6 mm thick, surface relatively smooth but with many longitudinal wrinkles, apex pointed. Fertile part irregularly attached on one side of the surface of distal part of stipe, which resembles a mass of insect eggs that are clustered together or separated into several lumps; substrate layer milky white, surface milky yellow accompanied by lavender and dotted with numerous black ostioles. Perithecia immersed, densely arranged, obliquely or at right angles to the surface of stipe, pyriform, neck unconspicuous, 220-290 × 120-150 µm and their tops obtuse; walls dark brown and 25-32 µm thick; ostioles slightly thickened and slightly protruding over the surface of fertile part. Asci cylindrical, 6-8 µm in diameter; caps hemispherical, 5-6 (x - = 5.5, n = 30) µm wide and 3.5-5 (x - = 4.2, n = 30) µm high. Ascospores filiform and elongate, multi-septate (far more than 3), not easy to break into part-spores; part-spores cylindrical, truncated at both ends, 10-15 (x - = 12.2, n = 30) × 2 μm. Asexual morph. Unknown.

Material examined.

Russia, the Russian Far East, Primorskiy Krai, National Park Land of the Leopard , Natural Reserve Kedrovaya Pad , 43°05'53.8"N, 131°33'17.8"E, 10 August 2016, Oksana Tomilova & Vadim Yu Kryukov (MFLU 18-0163, holotype; GACP R16002 and GACP R16003 , paratypes) .

Known distribution.

Russia (Primorskiy Krai).

Hosts.

Growing on Elateroidea larvae ( Coleoptera ) living in fallen wood in a deciduous forest.

Notes.

The new species is morphologically similar to O. purpureostromata (≡ C. purpureostromata ), but their stipes and ascospores are distinct. In O. purpureostromata , stipe is thicker (0.6-1 mm in diameter) and has hairs (0.25-0.6 mm in diameter and without hair in O. borealis ), ascospores are only 65-75 × 10 µm long and 3-septate (elongate and far more than 3-septate in O. borealis ) and part-spores are 13-23 µm long (10-15 µm long in O. borealis ) ( Kobayasi and Shimizu 1980b).

Nucleotide sequences of O. borealis are most similar to those of O. purpureostromata (specimen TNS F18430, Quandt et al. 2014), but there is 2.3% bp difference across the 804 bp in TEF1-α, 0.5% bp difference across the 845 bp in LSU and 0.1% bp difference across 1,061 bp in SSU. ITS of O. borealis is> 14.1% different to all ITS available in GenBank (ITS are not available for O. purpureostromata ). On the phylogenetic tree, the new species is also nearest (100% ML/100% MP/1.00 PP) to O. purpureostromata , but they form into two distinct branches which support them being two separate species (Fig. 1 ).

Figures

Figure 1. Maximum Likelihood (ML) tree of Ophiocordyceps borealis sp. nov., O. spicatus sp. nov. and their allies inferred from a combined SSU, LSU and TEF 1 - α gene dataset. Bootstrap support values of ML and Maximum Parsimony (MP)> 60 % and posterior probabilities (PP) of Bayesian Inference> 0.9, are indicated above the nodes and separated by ' / ' (ML / MP / PP).

Figure 2. Ophiocordyceps borealis a-c stromata arising from the different parts of larval bodies d apical ends of stromata e transverse section of fertile part, on which densely arranged perithecia are shown f asci g ascospores. Scale bars: 2 mm (a-c); 1 mm (d); 100 µm (e), 10 µm (f, g).