Conidiobolus jiangxiensis B. Huang & Y. Nie, 2024

Nie, Yong, Yin, Ying, Zhao, Heng, Liu, XiaoYong & Huang, Bo, 2024, Unveiling species diversity within the family Conidiobolaceae (Entomophthorales) in China: Descriptions of two new species and reassessment of the taxonomic position of Conidiobolus polyspermus, MycoKeys 105, pp. 203-216 : 203-216

Conidiobolus jiangxiensis B. Huang & Y. Nie sp. nov.

Fig. 2

Etymology.

jiangxiensis (Lat.), referring to the region where the fungus was isolated.

Known distribution.

Jiangxi Province, China.

Typification.

China, Jiangxi Province, Nanchang City, Aixihu Forest Wetland Park , 28 ° 69 ′ N, 115 ° 99 ′ E, from soil, 7 Dec. 2022, Y. Nie, holotype BWPU 221207 . Ex-type culture RCEF 7484 . GenBank: nucLSU = PP 034291 ; EFL = PP 035215 ; mtSSU = PP 034295 .

Additional specimens examined.

China, Jiangxi Province, Nanchang City, Aixihu Forest Wetland Park , 28 ° 69 ′ N, 115 ° 99 ′ E, from soil, 7 Dec. 2022, Y. Nie culture RCEF 7485 . GenBank : nucLSU = PP 034292 ; EFL = PP 035216 ; mtSSU = PP 034296 .

Description.

Colonies on PDA at 21 ° C after 3 d, white, reaching ca 11 mm in diameter. Mycelia white, 8–15 μm wide, often unbranched at the edge of colony, non-septate when young, and distended to segment after 7 d. Primary conidiophores often arising from hyphae, short, 30–95 × 7–10 μm, unbranched and producing a single primary conidium, without widening upward near the tip. Primary conidia forcibly discharged, globose to subglobose, 30–41 × 24–36 μm, papilla bluntly-round, 8–13 μm wide, 3.5–9 μm long. Secondary conidiophores arising from primary conidia, bearing a single similar but smaller replicative conidium to primary conidia. Microspores not observed on the PDA culture and on the 2 % water agar. Zygospores formed in axial alignment with conjugating segments after 10 days, mature zygospores smooth, usually globose, sometimes subglobose, 20–30 μm in diameter, with a 2–3 μm thick wall.

Notes.

Conidiobolus jiangxiensis , C. polyspermus and C. mycophilus exhibit close phylogenetic relatedness. However, the primary conidia and zygospores of C. jiangxiensis are smaller than those of C. polyspermus , and C. jiangxiensis is further set apart from C. mycophilus by its longer primary conidiophores and larger primary conidia ( Drechsler 1961; Srinivasan and Thirumalachar 1965). Despite the high similarities in nucLSU and EFL between C. jiangxiensis and C. polyspermus , their differentiation becomes evident through morphological traits. Similar instances of this phenomenon are observed in C. coronatus and C. megalotocus , as well as C. mycophagus and C. lichenicolus . Morphologically, C. jiangxiensis presents shorter primary conidiophores (no more than 95 μm) compared to the majority of other Conidiobolus s. s. members. It closely resembles C. marcosporus (50–100 μm), C. lichenicolus (30–100 μm), and C. gonimodes (20–80 μm) according to the length of primary conidiophores. Distinguishing features include its smaller primary conidia and zygospores in comparison to C. marcosporus ( Srinivasan & Thirumalachar, 1967) and larger primary conidia, as well as the absence of primary conidia arising as upward branches from hyphal knots, distinguishing it from C. lichenicolus ( Srinivasan and Thirumalachar 1968) . Notably, C. jiangxiensis aligns with C. gonimodes based on primary conidia size, yet it differs by the distinct width of mycelia and the presence of unbranched primary conidiophores ( Drechsler 1961). Furthermore, in the phylogenetic tree, C. jiangxiensis is distantly related to C. gonimodes . (Fig. 1 )

Figures

Figure 1. Maximum likelihood (ML) tree obtained by phylogenetic analyses of the combined nucLSU, EFL and mtSSU sequences. Two Azygosporus and three Microconidiobolus species were served as outgroups. The proposed new species is in boldface. Maximum Likelihood bootstrap values (≥ 70 %) / Bayesian posterior probabilities (≥ 0.95) of clades are provided alongside the branches. The scale bar at the bottom left indicates substitutions per site.

Figure 2. Conidiobolus jiangxiensis RCEF 7484 a colony on PDA after 3 d at 21 ° C b mycelia unbranched at the edge of the colony c hyphal segments d – g primary conidiophores bearing a single primary conidia h – k primary conidia l, m primary conidia bearing a single secondary conidium n, o zygospores formed between adjacent segments of the same hypha p young zygospores q mature zygospores. Scale bars: 100 μm (b); 20 μm (d – q).