Ophiostoma album Wang & Lu

Wang, HuiMin, Lun, YingYing, Lu, Quan, Liu, HuiXiang, Decock, Cony & Zhang, XingYao, 2018, Ophiostomatoid fungi associated with pines infected by Bursaphelenchusxylophilus and Monochamusalternatus in China, including three new species, MycoKeys 39, pp. 1-27 : 1

Ophiostoma album Wang & Lu sp. nov. Figure 3

Etymology.

The epithet reflects the white colour of the colonies.

Type.

CHINA, Zhejiang, Yuyao City, from Monochamus alternatus gallery of Pinus massoniana infested by numerous PWN, November 2012, collected by Q Lu and YY Lun, culture ex-holotype MUCL 55189 = CFCC 52168 = CXY1622.

Description.

Sexual form: Unknown. Asexual form: Hyalorhinocladiella -like. Conidiogenous cells micronematous, (4.2 –)9.5–16.5(– 20.5) × (0.5 –)1–2(– 2.5) μm; conidia hyaline, single-celled, aseptate, clavate or fusiform obovoid with pointed bases and (occasionally) rounded apices, slightly curved at the base (4 –)4.2–14.5(– 18) × (0.5 –)1–2(– 2.3) μm.

Culture characteristics.

Colonies on 2% MEA white, with the mycelium edge thinning radially; Hyphae are superficial on agar, sporulation weak. Colonies slowly growing, reaching 18.5 μm in diameter at 8 d at 25 °C, able to grow at 40 °C but not at 5 °C, with the optimal growth temperature of 35 °C. Growth characteristics on PDA culture medium are similar but the growth rate is slower than on MEA.

Habitat and distribution.

Galleries of Monochamus alternatus in Pinus massoniana , infested by PWN, in Zhejiang Province, China.

Additional specimens examined.

CHINA, Zhejiang, Yuyao City, from Monochamus alternatus galleries of Pinus massoniana infested by numerous PWN, November 2012, collected by Q Lu and YY Lun, MUCL 55190 = CFCC 52169 = CXY1642, CXY1643 = CFCC 52170.

Note.

Ophiostoma album only known in its asexual hyalorhinocladiella-like form. According to both ITS and tub2 based phylogenetic analysis, it is closely related to O. kryptum and O. olgensis in the O. minus complex (Figure 1). Ophiostoma album is easily distinguished from O. olgensis and O. kryptum based on their reproduction structure. Ophiostoma album only produces a hyalorhinocladiella-like asexual form in vitro, whereas the two other species produce both a sexual and asexual forms in vitro ( Jacobs and Kirisits 2003, Wang et al. 2016). The conidial size and shape of the three species are obviously different. Ophiostoma album produces clavate or fusiform to obovoid and sometimes, slightly curved conidia; these are obovoid with pointed bases in both O. olgensis and O. kryptum . Furthermore, the conidia of O. album are much larger, 4.2-14.5 × 1.0-1.9 μm vs. 1.5-7 × 1.5-5 μm in the two other species.