Moelleriella citrus X. L. Xu & C. L. Yang, 2025

Moelleriella citrus X. L. Xu & C. L. Yang sp. nov.

Fig. 9 View Figure 9

Etymology.

In reference to the generic name of host plants.

Diagnosis.

Similar to Moelleriella raciborskii in having pale yellow, thin, pulvinate stromata, M. citrus differs by its longer paraphyses and wider conidia.

Type.

CHINA • Sichuan Province, Chengdu City , Wenjiang District. Infected scale insects were found on the underside of leaves of Citrus sp., 30°42.40'N, 103°51.05'E, alt. 590 m, 10 Oct. 2020, X. L. Xu, XXL 202010001 ( SICAU 25-0078 – holotype preserved in the Herbarium of Sichuan Agricultural University; living culture SICAUCC 25-0059 – ex-holotype stored in the Culture Collection in Sichuan Agricultural University) GoogleMaps .

Description.

Parasitic on scale insect from citrus leaves ( Rutaceae ). Sexual morph: Not observed. Asexual morph: Coelomycetous. Stromata orange in fresh specimens, globose to subglobose, flattened pulvinate, 1.8–3.0 mm in diameter, surrounded by a hyaline hypothallus up to 1.6 mm wide and covered with confluent conidial masses of orange-yellow. Conidiomata simple and aggregated in the center of the stroma, and widely opened. Conidial masses orange. Conidia hyaline, smooth, one-celled, fusoid, with acute ends, produced in copious slime, 12–18.5 × 2.3–3.2 µm. Paraphyses present, arising from the hymenium of the conidioma, filiform, tapering at the apices, up to 85–100 µm long.

Culture characteristics.

Conidia germinate in sterile water within 12 h, with germination tubes typically growing laterally from both ends of the spore. Colonies on PDA at 25 ° C attaining 25 mm diameter in 20 days. Colonies pale yellow and formed compact pulvinate with abundant slimy masses. Conidial masses light yellow, the colony reverse dark yellow, and the margins pale yellow. Conidia hyaline, smooth, onecelled, fusoid, 12–15.5 × 2.0–2.8 µm. Paraphyses rare.

Host.

Scale insects ( Coccidae ).

Habitat.

Subtropical monsoon evergreen broad-leaf forests serve as the habitat for Moelleriella citrus , which infects scale insects found on the underside of Citrus sp. leaves. Infections are typically observed throughout the trees.

Distribution.

China, Sichuan Province, Chengdu City.

Material examined.

CHINA • Sichuan Province, Chengdu City, Wenjiang District . Infected scale insects were found on the underside of leaves of Citrus sp., 30°42.40'N, 103°51.05'E, alt. 590 m, 10 Oct. 2020, X. L. Xu, XXL 202010001 ( SICAU 25-0078 , living culture SICAUCC 25-0059 ) GoogleMaps ; • ibid. XXL 202010001-1 ( SICAU 25-0079 , living culture SICAUCC 25-0060 ) GoogleMaps .

Notes.

Moelleriella raciborskii is accepted as the teleomorph of Aschersonia placenta , which was previously linked to Hypocrella raciborskii ( Chaverri et al. 2008) . Morphologically, M. citrus is closely related to M. raciborskii , sharing characteristics such as a pale yellow, thin, pulvinate stroma, ovoid or subglobose tubercle processes developing on the periphery of the stroma, and orange ostioles. However, the paraphyses show differences in length, with our collection measuring 85–100 µm compared to 40–70 µm in the previous species, and our collection has larger conidia (12–18.5 × 2.3–3.2 µm vs. 11–14 × 1.5–2 µm) ( Liu et al. 2006).