Coryneum heveanum Senwanna, Cheewangkoon & K.D. Hyde

Senwanna, Chanokned, Hyde, Kevin D., Phookamsak, Rungtiwa, E. B. Gareth Jones, & Cheewangkoon, Ratchadawan, 2018, Coryneumheveanum sp. nov. (Coryneaceae, Diaporthales) on twigs of Para rubber in Thailand, MycoKeys 43, pp. 75-90 : 75

Coryneum heveanum Senwanna, Cheewangkoon & K.D. Hyde sp. nov. Figure 2

Etymology.

Named after the host on which it occurs, Hevea brasiliensis .

Type.

THAILAND, Chiang Rai Province, Wiang Chiang Rung District, on twigs (attached on tree) of Hevea brasiliensis , 1 November 2016, C. Senwanna, RBCR003 (MFLU 18-0936, holotype), ex-type living culture MFLUCC 17-0369, KUMCC 18-0106; Dry culture from ex-type MFLU 18-0936); ibid., RBCR016 (MFLU 17-1982, living culture MFLUCC 17-0376, dry culture MFLU 18-0937, MFLU 18-0938)

Description.

Associated with canker on twigs of Hevea brasiliensis . Asexual morph: Conidiomata acervular, solitary, erumpent through the outer periderm layers of host, scattered, surface tissues above slightly dome-shaped, black, velvety, formed of brown cell, thick-walled textura angularis, 145-540 µm diam. Conidiophores short, cylindrical, apically pale brown, paler at the base, smooth, septate, branched at the base, arising from basal stroma, 22-37 × 4-8 μm (x‒ = 28.5 × 5.6 μm, n = 15). Conidiogenous cell annellidic, integrated, terminal, cylindrical, medium brown, truncate apex, with 1-3 slightly percurrent proliferations, 6-17 µm long (x‒ = 10.7 μm, n = 20). Conidia curved, clavate to fusiform, dark brown, smooth-walled, 4-6-pseudo-septa, sometimes with apical and basal cells darker than other cells, rounded or sometime truncate at apex, truncate and black at the base, (40 –)43–53(– 68) × (14 –)15– 20 μm (x‒ = 48.7 × 17.3 μm, n = 85). Appressoria hyaline, globose to sub globose, thick-walled, 4-11 μm wide (x‒ = 7.1 μm, n = 20).

Cultural characteristics.

Conidia germinated on MEA within 24 h with germ tubes produced from one or both end cells, mostly from basal cell of conidia. Colonies on MEA reaching 20-25 mm diam. after 4 weeks at 25-30 °C, colonies circular, medium dense, cottony, margin wavy, superficial, slightly effuse, radially striated; colony from above, white, edges with more aerial mycelium than centre in the beginning and later become white grey, smooth with edge entire; from below: white to cream at the margin, yellowish-green in the centre in the beginning and later become dark green; not producing pigmentation in agar. Colonies on PDA reaching 10-15 mm diam. after 4 weeks at 25-30 °C, colonies circular, medium dense, cottony, slightly effuse, dark green with brown aerial mycelium on surface; not producing pigmentation in agar. Conidial masses were observed in PDA culture after 6 months at 25-30 °C. Mass of conidia dark brown to black, extruding on colony or tip of mycelium (Figure 2 q, r). Mycelium superficial and immersed, dark brown, hyphae branched, septate, constricted at septa, thick, smooth-walled (Figure 2 s).

Additional GenBank number.

SSU (primer NS1 and NS4; White et al. 1990) MH778705; MFLUCC 17-0369, MH778706; MFLUCC 17-0376, TEF1 (primer EF1-983F and EF1-2218R; Rehner 2001) MH780882; MFLUCC 17-0376.

Notes.

Phylogenetically, Coryneum heveanum clustered in the same clade with C. umbonatum , C. depressum , C. modonium , C. perniciosum and C. castaneicola with high statistical support. Based on morphological characters, the conidia of C. castaneicola , C. depressum , C. elevatum , C. modonium and C. umbonatum have slightly curved conidia with an apical cell with a hyaline tip, while C. heveanum , C. castaneicola and C. perniciosum lack a hyaline tip (Table 2) ( Briosi and Farneti 1908, Sutton 1980, Gadgil and Dick 2007, Senanayake et al. 2017, 2018). Coryneum heveanum is similar to C. betulinum , C. perniciosum , C. psidi and C. pyricola in having broadly fusiform or clavate conidia but differs in size of conidia and number of pseudosepta (Table 2).