Sporothrix pseudoabietina H. Wang, Q. Lu & Z. Zhang

Min Wang, Hui, Wang, Zheng, Liu, Fu, Xu Wu, Cheng, Fang Zhang, Su, Kong, Xiang Bo, Decock, Cony, Lu, Quan & Zhang, Zhen, 2019, Differential patterns of ophiostomatoid fungal communities associated with three sympatric Tomicus species infesting pines in south-western China, with a description of four new species, MycoKeys 50, pp. 93-133 : 114-116

Sporothrix pseudoabietina H. Wang, Q. Lu & Z. Zhang sp. n. Fig. 16

Etymology.

‘pseudoabietina’ (Latin), referring to the phylogenetic affinities to S. abietina .

Type.

CHINA, Yunnan, from T. minor galleries in P. yunnanensis , Apr. 2017, HM Wang, holotype CXY 1937, culture ex-holotype CFCC 52626 = CXY 1937.

Description.

Sexual form perithecial: on 2% MEA, perithecia superficial or partially immersed, with a globose base extending into a cylindrical neck, often terminated by ostiolar hyphae; bases (85-) 110-152 (-168) μm diam., black, the outer layer with dark brown hyphal ornamentation; apical neck mild to dark brown at the base, pale brown to pale yellow or hyaline toward the apex, straight or slightly curved, (172-) 560-985 (-1039) μm long, (37-) 41-62 (-78) μm wide at the base, (9.3-) 12.5-17.5 (-20) μm wide at the apex; ostiolar hyphae numerous, hyaline, divergent, (19.5-) 21.5-38.0 (-43) μm long; asci not seen; ascospores hyaline, 1-celled, orange-shaped in lateral view, ellipsoid in face view, circular in polar view, (2.9 -) 3.4-4.4 (-5.3) × (0.8-) 1.0-1.5 (-1.9) μm, without mucilaginous sheath.

Asexual form: Sporothrix -like. Conidiophores semi-macronematous to mononematous; conidiogenous cells hyaline, simple or loosely branched, smooth, bearing denticles disposed in a dense rachis (16.0-) 20.5-30.5 (-34.5) × (1.2-) 1.6-2.0 (-2.3) μm; conidia 1-celled, clavate, ellipsoid to ovoid, hyaline, (3.0-) 4.0-7.0 (-9.0) × (1.0-) 1.1-3.1 (-4.8) μm.

Culture characteristics.

Colonies on 2% MEA slow growing in the dark, reaching 23 mm in diam. in 8 days at 25 °C, growth rate up to 2.5 mm/day at the fastest; colony margin smooth. Hyphae appressed to flocculose or floccose, white; reverse hyaline to pale yellowish. Optimal growth temperature 25 °C; very slow growth at 35 °C; no growth at 5 °C.

Known substrate and hosts.

Galleries of Tomicus yunnanensis and T. minor in Pinus yunnanensis .

Known insect vectors.

Tomicus yunnanensis , T. minor .

Known distribution.

Yunnan Province, China.

Additional specimen examined.

CHINA, Yunnan, Tomicus minor galleries in Pinus yunnanensis , Apr. 2017, HM Wang, CFCC 52627 = CXY 1938.

Note.

Sporothrix pseudoabietina is characterised by a perithecial sexual form and a Sporothrix -like asexual state. Multiple phylogenetic inferences (LSU, ITS, TUB2 and CAL) showed that S. pseudoabietina belonged to the S. gossypina complex, in which it is closely related to S. abietina . However, it can be distinguished from this species, based on both morphological and physiological features. The conidia of S. pseudoabietina (4.0-7.0 × 1.1-3.1 μm) are wider than those of S. abietina (4-7.5 × 1-2 μm) ( Marmolejo and Butin 1990). Perithecia are known from S. abietina but only on natural substrates and not in vitro on artificial media, contrary to those from S. pseudoabietina . The perithecial neck in S. pseudoabietina is much longer than that of S. abietina , viz. mostly 560-985 μm and 450-650 μm, respectively. Ostiolar hyphae of S. abietina and S. pseudoabietina also differ in number, numerous vs 7-10 and size, mostly 13-19 μm and in S. pseudoabietina 21.5-38.0 μm (Fig. 11c, d). In addition, no growth of S. abietina was observed at 35 °C, but S. pseudoabietina can grow at 35 °C.

The hosts and geographic distributions of S. pseudoabietina and S. abietina are also very different. Sporothrix pseudoabietina was found associated with T. minor and T. yunnanensis infecting P. yunnanensis , whereas S. abietina was reported from Abies vejari attacked by Pseudohylesinus sp. in Mexico ( Marmolejo and Butin 1990).