Tulasnella tubericola K. Solís, J. Barriuso, A. Garcés-Claver & V. González, 2017

Solís, Karina, Barriuso, Juan José, Garcés-Claver, Ana & González, Vicente, 2017, Tulasnella tubericola (Tulasnellaceae, Cantharellales, Basidiomycota): a new Rhizoctonia-like fungus associated with mycorrhizal evergreen oak plants artificially inoculated with black truffle (Tuber melanosporum) in Spain, Phytotaxa 317 (3), pp. 175-187 : 181

Tulasnella tubericola K. Solís, J. Barriuso, A. Garcés-Claver & V. González , sp. nov. ( Fig. 1 )

MycoBank MB812221

Type:— SPAIN: ARAGÓN: Zaragoza, Centro de Investigación y Tecnología Agroalimentaria de Aragón ( CITA), 41° 43’ 28.48“ N, 0° 48’ 31.09“ W, 230 msl, in greenhouse, in culture pots, colonies in PDA isolated from ectomycorrhizal tips of one-year Quercus ilex subsp. ballota plants artificially mycorrhized with Tuber melanosporum , 9 April 2015, K. Solís, holotype strain EP-15 (deposited as living culture in the Spanish Type Culture Collection under the number CECT 20958), ITS sequence GenBank KX929166.

Diagnosis:—This species is characterized by the relatively fast growing-rate of its colonies in PDA medium that exhibits whitish-cream to pale orange-ochraceous tones, its radially filamentous appearance when young that become glossy in older cultures, thin-walled runner hyphae, the production of both typically barrel-shaped to globose monilioid cells together with terminal, finger-like, clavate or even subcapitate monilioid hyphal ends produced in restricted areas of aged cultures and its unique ITS sequence.

Colonies in PDA and CMA circular, filamentous, slow to moderately fast growing; in PDA colour at first white to cream-white, becoming pale cream to straw-ochraceous (2.5 Y /8/3) in older cultures, paler towards the centre (5 Y /8/3), flat to slightly raised profile with scarce aerial or tufted hyphae; radially filamentous appearance with adpressed hyphae in young colonies, granular to furfuraceous in older colonies, exhibiting a mucoid, shinny or glossy nature in some PDA cultures; true sclerotia absent but slightly raised aerial tufts made up of disperse groups of monilioid cells present in old cultures; margin diffuse to irregular, partially immersed in the substrate, filiform to moderately lobate. Reverse of the colony whitish-cream at first, then becoming pale orange-cream (2.5 Y /8/4) to light ochre (10 YR 8/6) in older cultures, paler in the centre of the colony. Runner hyphae mostly binucleate (although tri-nucleate elements are also present in older cultures), regularly septate, hyaline, thin-walled, (2.1)2.3–4.1(4.3) μm in diameter, cylindrical, sometimes laterally bifurcate in right angles and eventually constricted at the base of ramifications, frequently with monilioid-like, terminal finger-like, flexuose to flexuose-nodulose, clavate to fusoid or even subcapitate projections of (3.5)5–6.5 (9) × (25)30–75(80) μm, sometimes with divaricate branching ends. Monilioid cells binucleate, variable in shape and arrangement, ranging from ellipsoid to subglobose and mostly globose elements, of (1.,9)12–15(15.5) μm in diameter, sometimes with apiculate projections, in short and branched (mostly “ T ” shaped) chains, up to 20 elements, developed in loose clusters forming tufts along the entire colony. Growth rate in PDA at 28ºC, 0.1–0.3 mm /h. Basidiomata absent from seedlings samples or not produced after teleomorph-inducing techniques applied.

Etymology: —The specific epithet refers to the frequent association of this species with the ectomycorrhizal root tips of evergreen oak artificially inoculated with black truffle, Tuber melanosporum .

Additional isolates: —Colonies in PDA (isolates EP1 to EP14) isolated from Tuber melanosporum mycorhizal tips coming from 9 one-year old mycorrhizal plants of Q. ilex subsp. ballota artificially co-inoculated with a strain of Trichoderma harzianum , growing in pots in greenhouse under controlled conditions at the Centro de Investigación y Tecnología Agroalimentaria de Aragón-CITA, Zaragoza ( Spain).

Figures

FIGURE 1. Tulasnella tubericola CECT 20958 (holotype). a-c. morphological aspect in PDA culture (front view) at several temperatures; d. runner hyphae; e. monilioid-like hyphal elements; f. chains of monilioid cells; g. bi- and tri-nucleate hyphae