Leptographium pseudojilongense Z. Wang & Q. Lu, 2024

Wang, Zheng, Liu, Caixia, Song, Xiuyue, Tie, Yingjie, Wang, Huimin, Liu, Huixiang & Lu, Quan, 2024, Ophiostomatalean fungi associated with Polygraphus bark beetles in the Qinghai-Tibet Plateau, China, MycoKeys 110, pp. 93-115 : 93-115

Leptographium pseudojilongense Z. Wang & Q. Lu sp. nov.

Taxon 6, Fig. 9

Etymology.

The epithet pseudojilongense (Latin) refers to its sister species L. jilongense .

Holotype.

CXY 3312.

Description.

Sexual morph: not observed. Asexual morph: Leptographium - like. Conidiophores occurring singly, upright, arising directly from the mycelium, macronematous, mononematous, (247.7 –) 343.3–484.6 (– 513.7) μm in length including the conidiogenous apparatus, rhizoid-like structures absent. Stipes light olivaceous, not constricted, cylindrical, simple, 3–10 - septate, (98.8 –) 103.0–230.0 (– 301.2) μm in length, (9.0 –) 11.1–16.9 (– 18.6) μm wide at base, the basal cell swollen or not, (7.1 –) 8.5–14.2 (– 16.6) μm wide below primary branches, apical cell not swollen. Conidiogenous apparatus (100.8 –) 180.1–362.1 (– 417.4) μm in length, excluding the conidial mass, consisting of 1–4 series of branches, the primary branching type B. Primary branches light olivaceous, cylindrical, (15.4 –) 19.6–31.8 (– 35.4) × (6.2 –) 7.3–10.6 (– 12.3) μm; secondary branches light olivaceous, aseptate, (12.4 –) 13.3–16.7 (– 18.4) × (6.0 –) 6.4–9.5 (– 10.2) μm; tertiary branches light olivaceous or hyaline, aseptate, (8.0 –) 8.4–14.0 (– 16.1) × 5.3–7.6 (– 8.9) μm. Conidiogenous cells discrete, 2–3 per branch, smooth or rough, cylindrical, (16.9 –) 22.2–35.4 (– 52.6) × (3.9 –) 4.0–4.8 (– 5.1) μm. Conidia hyaline, smooth, aseptate, obovoid, (11.9 –) 12.9–15.7 (– 17.9) × (5.5 –) 6.3–7.8 (– 8.2) μm.

Culture characters.

Colonies on 2 % MEA at 25 ° C reaching a diameter of 50.1 mm in 4 days, initially hyaline or light white, later becoming light olivaceous from the centre of the colony to the sides, then becoming dark olivaceous, mycelium submerged and superficial with abundant aerial mycelia and the colony margin thinning radially. Optimal temperature for growth was 25 ° C, with slow growth observed at 5 ° C (45.3 mm in 30 days) and no growth at 35 ° C.

Associated insects.

Polygraphus rudis .

Hosts.

Pinus griffithii .

Material examined.

China • Xizang Autonomous Region, Shigatse City , Jilong County, from Polygraphus rudis infesting Pinus griffithii , July 2019, Z. Wang and Q. Lu, holotype: CXY 3312 , ex-type culture CFCC 57901 , ibid. CXY 3348 , CXY 3349 .

Notes.

Leptographium pseudojilongense was a phylogenetic sister to L. griffithii and L. jilongense (Fig. 9 ), both of which were associated with Pinus griffithii in Shigatse, Xizang ( Wang et al. 2024). Leptographium pseudojilongense can be distinguished from L. griffithii in the concatenated alignment by 1 / 373 bp in tub 2 and 3 / 666 bp in tef 1 - α and from L. jilongense in the concatenated alignment by 3 / 666 bp in tef 1 - α. In terms of morphological characteristics, L. pseudojilongense can be distinguished from the other two species by the presence of a leptographium - like asexual state, which is absent in the latter two. For culture characteristics, the optimum growth temperature for both was 25 ° C, but the former grew slower than the latter two (4 days: 50.1 mm vs. 64.5 and 76.0 mm). At 5 ° C, L. pseudojilongense was observed growing slowly with 45.3 mm in 30 days, whereas the other two did not grow. Furthermore, L. pseudojilongense was isolated from Jilong County, whereas L. griffithii and L. jilongense were isolated from Ips schmutzenhoferi from Yadong County and Ips stebbingi from Jilong County, respectively.

Figures

Figure 9. Morphological characteristics of Leptographium pseudojilongense sp. nov. (Taxon 9, CXY 3312, holotype) A four-day-old cultures on 2 % MEA B – E Leptographium - like asexual morph: conidiogenous cells and conidia. Scale bars: 10 μm (B, D, E); 40 μm (C).