Polycephalomyces formosus Kobayasi, 1941

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

Polycephalomyces formosus Kobayasi Fig. 4

Remarks.

Polycephalomyces formosus was reported on Coleoptera larvae, stromata of Ophiocordyceps barnesii (Thwaites) G.H. Sung et al., O. falcata (Berk.) G.H. Sung et al. and O. cantharelloides (Samson & H.C. Evans) G.H. Sung et al. and distributed in Ecuador, Japan and Sri Lanka ( Kobayasi 1941; Samson and Evans 1985; Wang 2016). We collected a P. formosus -like specimen on the stroma of Ophiocordyceps sp. on an Elateroidea larva from Guizhou, China. Morphological and phylogenetic data showed that it is P. formosus . This is the first report of P. formosus on wireworms.

Asexual morph.

Growing on the stroma of Ophiocordyceps sp. on an Elateroidea larva. Stroma single, arising from the body end of the host larva, unbranched. The larva reddish-brown, cylindrical, 21 × 1.3-1.6 mm, intersegmental membranes conspicuous. Stipe of the stroma shiny black, stiff, band-like, but twisted and deeply wrinkled (dry specimen), more than 20 mm long and 1.0-1.3 mm thick, surface smooth (the fertile head was missing). Synnemata solitary or caespitose, arising from the intersegmental membranes of the larva and the surface of the stroma, mostly unbranched, generally straight, capitate, 1-3.5 mm long and 50-600 µm thick. Stipe basally broad and compressed, then gradually cylindrical upwards, white, greyish-white to yellowish-brown, surface smooth. Fertile head (including spore mass) abruptly expanded, ellipsoidal, 100-300 × 80-250 µm, located at the top of every synnema and distinctly separated from the stipe. Spore mass covers the surface of every fertile head, 15-25 µm thick, yellowish-brown and composed of hymenia. Phialides of two types, A-phialides produced on fertile heads, B-phialides arising laterally along the entire stipe. A-phialides 3-5 in terminal whorl on basal conidiophores, cylindrical to narrowly conical, straight or curved, non-uniform, 10-20 (x - = 15.1, n = 30) µm long and 1.5-2 µm (x - = 1.7, n = 30) wide, basally and terminally narrow, neck narrow to 0.5 µm, collarettes and periclinal thickening not visible; A-conidia obovate to obpyriform, smooth-walled, hyaline, 2.1-3.2 (x - = 2.6, n = 30) µm long and 1.5-2.2 (x - = 1.8, n = 30) µm wide. B-phialides single or in terminal whorls of 2-3 on basal conidiophores, straight, symmetrical or asymmetrical, hyaline, generally cylindrical, 10-25 (x - = 17, n = 30) µm long, 2-3.5 (x - = 2.8, n = 30) µm thick at the base, 0.5-0.8 (x - = 0.65, n =30) µm thick at the end, collarettes and periclinal thickening not visible; B-conidia fusiform, hyaline, smooth-walled, 3.2-6.0 (x - = 4.6, n = 30) µm long and 1-1.8 (x - = 1.4, n = 30) µm wide. Sexual morph. Not observed.

Material examined.

CHINA, Guizhou, Tongzi County, Baiqing Natural Reserve , 28°52'31"N, 107°9'10"E, about 1300 m alt., 13 July 2016, Ling-Sheng Zha (MFLU 18-0162) .

Notes.

Polycephalomyces formosus was originally described from Japan as: growing on Coleoptera larvae; synnemata solitary or caespitose, 1-3.5 mm long and 100-250 µm thick; spore mass covering the surface of the fertile head, 15-25 µm thick; A-phialides 3-4 in terminal whorl on basal conidiophores, cylindrical to narrowly conical, 10-20 × 1.5-2 µm, neck 0.5 µm; A-conidia obovate to obpyriform, 2.0-2.8 × 1.6-2.0 µm; B-conidia fusiform, 3.2-4.8 × 0.8-1.6 µm ( Kobayasi 1941; Wang 2016). These characteristics are all consistent with our specimen. Sequences of SSU, ITS, LSU and TEF1-α are all identical to those of P. formosus (specimen ARSEF 1424); and in our phylogenetic tree, these two samples grouped together and have a same branch length (Fig. 1 ).

Host and ecology.

On the stroma of Ophiocordyceps sp. on an Elateroidea larva on the ground in a humid bamboo ( Chimonobambusa quadrangularis (Franceschi) Makino) forest in Guizhou karst regions.

The larva might live in soil or decayed wood at first, but was then infected by Ophiocordyceps sp. and produced a sexual stroma. Following heavy rainfall, the host, together with the stroma of Ophiocordyceps sp., was washed away and exposed on the ground and at last, was parasitised by Polycephalomyces formosus . The fertile head of the stroma might have been lost during the floods.

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 4. Polycephalomyces formosus (MFLU 18 - 0162) a collected on the ground in a bamboo forest b produced on the stroma of Ophiocordyceps sp. (the fertile head was missing) on an Elateroidea larva c, d synnemata e-g A-type phialides and A-type conidia h B-type phialides and B-type conidia. Scale bars: 20 µm (e); 5 µm (f); 10 µm (g, h).