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).