Microcera chrysomphaludis Feng Liu & C.L. Yang, sp. nov.

Liu, Feng, Deng, Yu, Wang, Fei-Hu, Jeewon, Rajesh, Zeng, Qian, Xu, Xiu-Lan, Liu, Ying-Gao & Yang, Chun-Lin, 2023, Morphological and molecular analyses reveal two new species of Microcera (Nectriaceae, Hypocreales) associated with scale insects on walnut in China, MycoKeys 98, pp. 19-35 : 19

Microcera chrysomphaludis Feng Liu & C.L. Yang, sp. nov.

Figs 4 , 5

Etymology.

In reference to the generic name of scale insect from which it was isolated.

Holotype.

SICAU 22-0162.

Host.

Chrysomphalus aonidum ( Diaspididae , Homoptera )

Habitat.

On the trunk of Juglans regia .

Sexual state.

Perithecia 285-429 μm high, 216-386 µm diam. (x-= 350 × 290 μm, n = 50), scattered, gregarious, formed directly on margin of host scales, bright red to dark red, subglobose, ellipsoidal in section, a central, rounded, papillate ostiole, lined internally with periphyses. Peridium 62-95 µm thick, comprising two layers, outer stratum 32-55 µm thick, composed of small, hyaline to light brown cells of textura angularis; inner stratum 35-45 µm thick, composed of thinner, orange cells of textura angularis; thicker at sides towards apex, thinner at base. Hamathecium 8.5-19.2 µm diameter (x-= 12.3 µm, n = 30), longer than asci, septate, unbranched, paraphyses. Asci 83.3-128.5 × 7.5-15.2 µm (x-= 109.2 × 10.2 μm, n = 50), 8-spored, bitunicate, cylindrical, straight or curved, rounded at apex. Ascospores 16.8-27.5 × 7.8-10.8 µm (x-= 20.9 × 9.6 µm, n = 50), uniseriate, elliptical, with rounded ends, one-septate, slightly constricted at septum, hyaline, smooth-walled, with many guttules.

Asexual state.

Stromata byssoid, pale yellow, formed directly on margin of host scales with 1-6 sporodochia. Sporodochia conical, erupted, yellowish, scattered or aggregated. Macroconidia 73-89 long, 6.9-10.6 µm wide (x-= 78.8 × 8.5 μm, n = 50), hyaline, cylindrical, slightly curved, slender towards each end, 2-7 septa, mostly 4-6 septa, slightly constricted at septum, difficult to distinguish apical cell and basal cell. Microconidia and chlamydospores were not observed.

Material examined.

China, Sichuan Province, Liangshan Yi Autonomous Prefecture , Huili County (26°56′43″N, 107°16′16″E, alt. 1780 m), on scale insect Chrysomphalus aonidum , 8 October 2022, Feng Liu, LF 202208001, (SICAU 22-0162, holotype), ex-type culture SICAUCC 22-0164. Ibid. LF 202008002 (SICAU 22-0163, paratype), living culture SICAUCC 21-0165 .

Culture characters.

Ascospores germinate on PDA within 12 h and cultures grow slowly on PDA. Colonies reach 2.4 cm in diameter after 20 days. Colonies from single conidia flocculent, clinging to medium, with irregular margin, white to pink mycelium on surface and back of colonies dark orange. Mycelium creamy-white starting at centre, but gradually becoming pale pink after 20 days, forming sparsely distributed mycelial clumps near edge of colony. Conidia germinate on PDA within 12 h, cultures grow slowly on PDA. Colonies 2.5 cm in diameter after 20 days. Colonies from single ascospores cottony and hard, with regular margin; mycelium creamy-white to pale pink, with concentric rings; back of colonies pale yellow.

Notes.

Multi-gene phylogenetic analyses have revealed that Microcera chrysomphaludis forms a highly robust clade that is closely related to M. coccophila and M. diploa . However, it is distinct from these two species with a high level of bootstrap support (ML/BY 100/1.00; Fig. 1 ). Morphologically, M. chrysomphaludis exhibits similar characteristics to M. coccophila , including superficial, subglobose, bright red ascomata, cylindrical asci and elliptical ascospores, as well as cylindrical macroconidia. However, M. chrysomphaludis can be differentiated from M. coccophila by its larger ascomata (285-429 × 216-386 µm vs. 194-387 × 194-355 μm), slightly shorter asci (109.2 × 10.2 μm vs. 115 × 15 µm), longer ascospores (16.8-27.5 × 7.8-10.8 μm vs. 14-19 × 6-10 μm) and shorter macroconidia (73-89 × 6.9-10.6 µm vs. 90-132 × 6-9 µm) and fewer septa (4-6 vs. 7-9) ( Gräfenhan et al. 2011; Dao et al. 2015). Hence, we describe our collection as a new species in Microcera .

Figures

Figure 1. Phylogram generated from RAxML analysis, based on combined ITS, LSU, tef 1 - α, rpb 1, r pb 2, a cl 1, act, tub 2, cmd A and his 3 sequence data of Microcera isolates. Bootstrap support values from Maximum Likelihood (MLBS, left) higher than 75 % and Bayesian posterior probabilities (BIPP, right) equal to or greater than 0.95 are indicated at the nodes, respectively. The sequences from ex-type strains are in bold. The newly-generated sequence is in red.

Figure 4. Microcera chrysomphaludis (SICAU 22 - 0162) a, b ascomata on host substrate c vertical section through ascostromata d peridium e ostiole of locule f paraphyses h ocular chamber g-j asci k-o ascospores p germinated ascospores; q, r colonies on PDA after 30 days. Scale bars: 200 µm (a, b); 50 µm c, 20 µm (d, e); 10 µm (f - p).

Figure 5. Microcera chrysomphaludis (SICAU 22 - 0163) a-c stromata and sporodochia on host substrate d-g conidiophore with developing macroconidia h-l macroconidia m germinated conidium n, o colonies on PDA after 30 days. Scale bars: 200 µm (b, c); 20 µm (d-g); 10 µm (h-m).