Takamatsuella grandii M. Bradshaw, 2025

LaGreca, Scott, Crouch, Uma, Paul, Andrew, Thomas, Jacklyn, Thompson, Jake, Shaw, Christian, Cubeta, Marc A., Braun, Uwe & Bradshaw, Michael, 2025, Hidden treasures of herbaria - even small collections contain a wealth of diversity: the powdery mildews of the North Carolina State Larry F. Grand Mycological Herbarium, IMA Fungus 16, pp. e 156231-e 156231 : e156231-

Takamatsuella grandii M. Bradshaw sp. nov.

Fig. 9

Etymology.

Epithet in honor of NCSU mycologist Larry F. Grand.

Diagnosis.

Takamatsuella grandii differs morphologically from T. circinata in having appendages with walls uniformly 3 µm thick, and genetically by forming a highly supported clade.

Type.

USA • North Carolina, Wake County, Ligon Street, Raleigh , on leaves of Acer saccharum , 5 November 1980, M. Daykin s. n. ( NCSLG 24386 — holotype). Ex-holotype sequences: PV 416651 (ITS), PV 409641 (IGS) .

Description.

Mycelium on abaxial surfaces of leaves, effuse, thin, arachnoid, grayish white; hyphae dichotomously branched, hyaline, thin-walled, smooth, septate; hyphal appressoria nipple-shaped; anamorph not seen. Chasmothecia scattered to + / - gregarious, depressed globose, 120–170 µm in diameter; peridium cells irregularly polygonal, light brown, 7–15 × 14–19 µm; appendages very numerous, up to 150 per chasmothecium, arising below the equator, stiff to flexuous, simple, apices tightly uncinate to circinate, not enlarged, about 0.3–1 times as long as the chasmothecial diameter, uniformly 2–6 µm wide and walls uniformly 3 µm thick, hyaline, aseptate, smooth, thin-walled; asci up to 8 or more, clavate-saccate, 70–90 × 25–40 µm, usually stalked, wall uniformly 3 µm thick, 8 - spored; ascospores ellipsoid-obovoid, 10–25 × 9–20 µm, hyaline.

Additional specimens examined.

USA • North Carolina, Wake County, Schenck Research Forest, Raleigh , on leaves of Acer saccharum , in floodplain along stream, 35°48.958'N, 78°44.020'W, 165 m alt., 26 October 2011, L. F. Grand s. n. ( NCSLG 18506 ) ; • Wake County, Schenck Research Forest, Raleigh , on leaves of Acer saccharum (= A. barbatum , ≡ A. saccharum var. barbatum , ≡ A. saccharum f. barbatum ; = A. dasycarpum ), 6 October 1998, G. Blosser 32 ( NCSLG 24381 ) .

Substrate / host.

Acer saccharum .

Distribution

(based on specimens on Acer saccharum deposited in North American herbaria): North America ( USA: Indiana, New York, New Hampshire, North Carolina, Pennsylvania).

Notes.

Takamatsuella grandii is an undescribed cryptic species infecting different Acer species to those of T. circinatum . The host of the type specimen of T. circinata is Acer spicatum ( Acer sect. Spicata ) ( Braun and Cook 2012). Additional Acer spp. cited as host species of T. circinata are A. glabrum (unresolved name), A. nigrum ( Acer sect. Acer ser. Saccharodendron ), A. pensylvanicum ( Acer sect. Macranthum ), A. rubrum ( Acer sect. Rubra ), A. saccharum ( Acer sect. Acer ser. Saccharodendron ), and A. saccharinum ( Acer sect. Rubra ); subgeneric affiliations according to Davis (2021). Phylogenetic analyses of specimens of Takamatsuella on Acer saccharum revealed the existence of a cryptic species on this host, now referred to as T. grandii . The new species presented here is morphologically very close to T. circinata but differs in having appendages with walls uniformly 3 µm thick (versus thin-walled or only thickened at the base). The affinity of Takamatsuella species on the other host species listed above remains unclear since they belong to different sections of Acer . Based on the currently available sequences, as well as the high degree of co-evolution within this group of powdery mildews, it can be assumed that the Takamatsuella species on Acer nigrum might be T. grandii , whereas specimens on A. rubrum and A. saccharinum (sect. Rubra) are expected to be part of the host range of T. circinata , pending molecular confirmation.

Figures

Figure 9. Takamatsuella grandii sp. nov. (a From NCSLG 18506 b – d from NCSLG 24386) a habit, on leaves of Acer saccharum b chasmothecium showing peridium cells and appendages with circinate ends c split chasmothecium showing appendages and emerging asci d close-up of asci with ascospores. Scale bars: 1 mm (a); 100 µm (a, c); 10 µm (d).