Leptographium rhizoidum M.L. Yin, Z.W. de Beer and M.J. Wingf.

Yin, Mingliang, Wingfield, Michael J., Zhou, Xudong, Linnakoski, Riikka & Beer, Z. Wilhelm de, 2019, Taxonomy and phylogeny of the Leptographium olivaceum complex (Ophiostomatales, Ascomycota), including descriptions of six new species from China and Europe, MycoKeys 60, pp. 93-123 : 93

Leptographium rhizoidum M.L. Yin, Z.W. de Beer and M.J. Wingf. sp. nov. Fig. 6

Etymology.

The epithet refers to the rhizoid-like structures at the synnematal bases.

Type.

SPAIN, Morga, from Pinus radiata infested by Hylastes ater , July. 2004, P. Romon & X.D. Zhou, (PREM 60922- holotype, ex-holotype cultures: CBS 136512 = CMW 22809); Morga, from Pinus radiata infested by Hylastes attenuatus , July. 2004, P. Romon & X.D. Zhou, (PREM 60923- paratype, ex-paratype cultures: CBS 136513 = CMW 22810).

Description.

Sexual state not observed. Conidiophores macronematous, synnematous, 200-350 μm including conidiogenous apparatus, synnemata frequently swollen at the base, frequently wider at the stipe, brown to light brown, expanding branches at the apex, (15 –)35–45(– 70) μm in width. Conidiogenous cells discrete, terminal, percurrent and phialidic proliferation, hyaline, cylindrical,(10 –)14–17(– 19) × 2-3 μm. Conidia hyaline, one-celled, cylindrical to obovoid, (5.1 –)6.5–7.8(– 10.5) × 2.1-3.5 μm. Cultural characteristics: Colonies on OA, hyaline at first, later becoming olivaceous in the center, hyphae hyaline, appressed and immersed, aerial mycelium frequently present on wood tissue, synnemata abundant in WA cultures, Optimal growth temperature on MEA is 25 °C with radial growth rate 6.0 ( ± 0.5) mm/d, growth slightly reduced at 10 °C and 35 °C.

Host tree.

Pinus radiata .

Insect vectors.

Hylastes ater , H. attenuatus , Hylurgops palliatus , Ips sexdentatus .

Distribution.

Spain.

Note: Isolates of L. rhizoidum from pine-infesting bark beetles in Spain were initially identified as L. olivaceum based on ITS sequences by Romon et al. (2007). Our data showed them to be distinct from that species. This species produced more abundant and longer rhizoids than others in the complex.

Other Material examined: SPAIN, Morga, from Pinus radiata infested by Ips sexdentatus , July. 2004, P. Romon & X.D. Zhou, (culture: CMW 22811); Morga, from P. radiata infested by Hylurgops palliatus , July. 2004, P. Romon & X.D. Zhou, (culture: CMW 22812).

Figures

Figure 6. Leptographium rhizoidum sp. nov. (CMW 22809). a fourteen-days old culture on OA with black background b synnematous asexual state on wood tissue on WA c conidiophore d conidiogenous apparatus e conidiogenous cells f conidia. Scale bars: 200 μm (b), 50 μm (c), 20 μm (d), 10 μm (e), 5 μm (f).