Camposporium aquaticum L. L. Liu & Z. Y. Liu 2025, sp. nov.

Camposporium aquaticum L. L. Liu & Z. Y. Liu sp. nov. Fig. 3 Etymology. Refers to the aquatic habitat of this fungus. Holotype. GZAAS 20-0376. Description. Saprobic on decaying, submerged wood in a freshwater habitat. Asexual morph. Colonies on natural substrate effuse, brown, procumbent. Mycelium partly immersed and partly superficial, composed of pale brown, septate, cylindrical hyphae. Conidiophores macronematous, mononematous, irregularly cylindrical, strongly flexuous to twisted, procumbent, brown, sometimes fading slightly towards the apex, smooth-walled, unbranched, thick-walled, 4–8 – septate, 75–92 × 5.5–6.5 μm (x ̄ = 86 × 6 μm, n = 20). Conidiogenous cell: holoblastic, monoblastic, integrated, terminal, cylindrical, pale brown. Conidia solitary, cylindrical to narrowly fusoid, elongate, subhyaline to pale olivaceous green when young, brown or pale brown when mature, polar cells slightly paler, 64–114 × 7.5–11.5 μm (x ̄ = 91.5 × 9.5 μm, n = 30), smooth-walled, verruculose, 6–13 - septate, often slightly constricted at the septa, basal cell conical, apical cell rounded with 2 independent, simple, cellular, aseptate, hyaline, smooth, straight, curved, or flexuous appendages, 29.5–40 × 1.5–2.5 μm (x ̄ = 33 × 1.8 μm, n = 20). Sexual morph. Undetermined. Cultural characteristics. Conidia germinated on WA within 24 h, and germ tubes were produced from the apex. The colonies on PDA reached approximately 22 mm diam. after 3 weeks at 25 ° C under dark conditions. Colonies circular, with raised center and filamentous edge, grey at center, brown at the edge from above, dark brown in the center, brown at the edge from reverse. Material examined. China • Guizhou Province, Guiyang City, Baihua Lake, near 26°39'18.20"N, 106°32'12.90"E, at 1205 m altitude, on a decaying branch submerged in the lake, 18 April, 2018, Lingling Liu, 18 B-107 (GZAAS 20-0376, holotype); • ex-type living culture, ACCC 35528. Taxonomic notes. Phylogenetic analyses of the combined LSU, SSU, ITS, and tef 1 - α sequence dataset showed that C. aquaticum (ACCC 35528) is sister to C. guizhouense (GZCC 19-0480) and formed a distinct lineage. We compared the base pair differences between the two new taxa and found six base pair differences (1.27 %) across 471 nucleotides in the ITS gene region. Additionally, comparing the 972 nucleotides across the tef 1 - α gene region between ACCC 35528 and GZCC 19-0480 shows a 17 base pair difference (1.75 %). Morphologically (Table 3), C. aquaticum (ACCC 35528) conidia resemble C. guizhouense conidia. However, C. aquaticum conidia (64–114 × 7.5–11.5 μm) are substantially larger than C. guizhouense conidia (58–81.5 × 7–9 μm), and C. aquaticum conidia are 6–13 - septate, whereas C. guizhouense conidia are 8–11 - septate (mostly 10). PHI analysis further confirmed that C. aquaticum (ACCC 35528) showed no significant genetic recombination with closely related species (Fw> 0.05, Fig. 4). Therefore, we introduce C. aquaticum (ACCC 35528) as a novel species.