Uncovering cryptic species diversity of Ophiocordyceps (Ophiocordycipitaceae) associated with Coleoptera from Thailand

Abstract

This study advances our understanding of Ophiocordyceps, an extensively studied entomopathogenic fungus within the Ophiocordycipitaceae, particularly in Thailand. We introduce seven novel species associated with Coleoptera - O. albostroma, O. brunnea, O. capilliformis, O. kohchangensis, O. phitsanulokensis, O. pseudovariabilis, and O. ratchaburiensis. Remarkably, O. brunnea, O. kohchangensis, and O. ratchaburiensis exhibit ascomata on the subterminal region of the stromata, with the asexual form appearing at the apex of the stipe, reminiscent of O. brunneipunctata. In contrast, O. phitsanulokensis produces its ascomata in the upper region of the stipe. Shared traits include immersed perithecia and part-spores production. Ophiocordyceps albostroma and O. pseudovariabilis produce pseudo-immersed perithecia, with the former producing ascospores breaking into four part-spores, and the latter displaying 32 part-spores. Ophiocordyceps capilliformis is also introduced due to morphological distinctions from closely related species. Phylogenetic analyses based on multigene loci (LSU, TEF1, RPB1, RPB2) robustly confirm the placement of these new species within Ophiocordyceps. Additionally, we report a new record of O. clavata in Thailand. Citation: Mongkolsamrit S, Noisripoom W, Tasanathai K, Khonsanit A, Thanakitpipattana D, Lamlertthon S, Himaman W, Crous PW, Stadler M, Luangsa-ard JJ (2024). Uncovering cryptic species diversity of Ophiocordyceps (Ophiocordycipitaceae) associated with Coleoptera from Thailand. Fungal Systematics and Evolution 14: 223-250. doi: 10.3114/fuse.2024.14.15.

Keywords: Ascomycota; Coleoptera; Ophiocordyceps; new taxa; pathogenic fungi; phylogeny.

Fig. 1

RAxML tree of Ophiocordyceps and related genera in the Ophiocordycipitaceae from a combined LSU, TEF1, RPB1 and RPB2 dataset. Numbers at the major nodes represent Maximum Likelihood Bootstrap (MLB) support values and Bayesian Posterior Probabilities (BPP).

Fig. 2

Ophiocordyceps albostroma. A–D. Fungus on coleopteran larvae. E. Fertile part. F. Perithecia. G. Asci. H. Part-spores. Scale bars: A–D = 10 mm; E = 4 mm; F = 200 μm; G = 20 μm; H = 30 μm.

Fig. 3

Ophiocordyceps brunnea. A, B. Fungus on coleopteran larvae. C. Close-up of fertile head. D. Perithecia. E, F. Asci. G. Ascus. H. Part-spores. I, J. Phialides with conidia. K, L. Colonies on MYA at 30-d-old (K obverse, L reverse). M–O. Phialides with conidia on MYA. P. Conidia on MYA. Q, R. Colonies on OA at 30-d-old (Q obverse, R reverse). S, T. Phialides on OA. U. Conidia on OA. V, W. Colonies on PDA at 30-d-old (V obverse, W reverse). X, Y. Phialides on PDA. Z. Conidia on PDA. Scale bars: A, B = 5 mm; C = 1 mm; D = 200 μm; E, F, I, J, M–O, S, T, X, Y = 20 μm; G, H, P, U, Z = 10 μm; K, L, Q, R, V, W = 15 mm.

Fig. 4

Ophiocordyceps capilliformis. A. Fungus on coleopteran larva. B. Close-up of ascoma region. C. Perithecia. D. Asci. E. Whole ascospore. F–H. Phialide and conidia. I, J. Colonies on MYA at 30-d-old (I obverse, J reverse). K, L. Phialides with conidia on MYA. M, N. Conidium on MYA. O, P. Colonies on OA at 30-d-old (O obverse, P reverse). Q. Phialide with conidium on OA. R–T. Conidia on OA. U, V. Colonies on PDA at 30-d-old (U obverse, V reverse). W, X. Phialides with conidia on PDA. Y, Z. Conidium on PDA. Scale bars: A, I, J, O, P, U, V = 15 mm; B = 5 mm; C = 200 μm; D = 15 μm; E, K = 20 μm, F, H, L = 10 μm; G, M, N, Q–T = 5 μm; W, X = 12 μm; Y, Z = 4 μm.

Fig. 5

Ophiocordyceps clavata. A, B. Fungus on coleopteran larvae. C. Perithecia. D. Asci. E. Ascus tips. F–H. Part-spores. I, J. Colonies on MYA at 30-d-old (I obverse, J reverse). K, L. Phialides with conidia on MYA. M. Conidia on MYA. N, O. Colonies on OA at 30-d-old (N obverse, O reverse). P, Q. Phialides on OA. R. Conidia on OA. S, T. Colonies on PDA at 30-d-old (S obverse, T reverse). U, V. Phialides on PDA. W. Conidia on PDA. Scale bars: A, B = 5 mm; C = 150 μm; D = 100 μm; F, M, P–R, U–W = 10 μm; G, K = 50 μm; E, H, L = 20 μm; I, J, N, O, S, T = 15 mm.

Fig. 6

Ophiocordyceps kohchangensis. A–C. Fungus on coleopteran larvae. D, E. Perithecia. F, G. Asci. H. Part-spores. I. Phialides. J. Conidia. K, L. Colonies on MYA at 30-d-old (K obverse, L reverse). M, N. Phialides on MYA. O. Conidia on MYA. P, Q. Colonies on OA at 30-d-old (P obverse, Q reverse). R, S. Phialides on OA. T. Conidia on OA. U, V. Colonies on PDA at 30-d-old (U obverse, V reverse). W, X. Phialides on PDA. Y. Conidia on PDA. Scale bars: A, C, K, L, P, Q, U, V = 15 mm; B = 10 mm; D, E = 200 μm; F = 100 μm; G, R, S, Y = 10 μm; H, J, M–O, T = 5 μm; I, W, X = 20 μm.

Fig. 7

Ophiocordyceps phitsanulokensis. A–C. Fungus on coleopteran larvae. D. Perithecia. E. Asci. F. Part-spores. G. Phialides. H. Conidia. I, J. Colonies on OA at 30-d-old (I obverse, J reverse). K, L. Phialides and conidia on OA. M. Conidia on OA. N, O. Colonies on PDA at 30-d-old (N obverse, O reverse). P–R. Phialides and conidia on PDA. S. Conidia on PDA. Scale bars: A–C = 10 mm; D = 500 μm; E = 50 μm; F, G, H, L, M, Q–S, K = 10 μm; P = 20 μm; I, J, N, O = 15 mm.

Fig. 8

Ophiocordyceps pseudovariabilis. A, F. Fungus on coleopteran larvae. B. Perithecia. C. Asci. D. Ascus tip. E. Part-spores. G–I. Phialides. J. Conidia. K, L. Colonies on MYA at 30-d-old (K obverse, L reverse). M, N. Phialides with conidia and immature conidia (arrows) on MYA. O. Conidia on MYA. P, Q. Colonies on PDA at 30-d-old (P obverse, Q reverse). R, S. Phialides with conidia and immature conidium (arrow) on PDA. T. Conidia on PDA. Scale bars: A, F = 5 mm; B = 100 μm; C = 50 μm; D, E, G–J, N, O = 10 μm; K, L, P, Q = 15 mm; M, R–T = 20 μm.

Fig. 9

Ophiocordyceps ratchaburiensis. A, B. Fungus on coleopteran larvae. C. Fertile part, D. Perithecia. E. Asci. F, G. Part-spores. H, I. Phialides. J. Conidia. K, L. Colonies on OA at 30-d-old (K obverse, L reverse). M, N. Phialides on OA. O. Conidia on OA. P, Q. Colonies on PDA at 30-d-old (P obverse, Q reverse). R, S. Phialides on PDA. T. Conidia on PDA. Scale bars: A, B = 10 mm; C = 2 mm; D, E = 100 μm; F–J, O, T = 10 μm; K, L, P, Q = 15 mm; M, N, R, S = 20 μm.