Atrokylindriopsis racemosospora Senwanna, J. Kumla & N. Suwannar., 2025

Atrokylindriopsis racemosospora Senwanna, J. Kumla & N. Suwannar. sp. nov.

Fig. 2 View Figure 2

Etymology.

In reference to the spore arrangement resembling a raceme form.

Type.

Thailand • Chiang Mai Province: Chai Prakan District, Nong Bua Subdistrict , endolichenic from the medulla of foliose lichen ( Parmotrema sp. ) on Prunus domestica , 19°42'23"N, 99°1'32"E, elevation 1160 m, 2 June 2023, C. Senwanna and N. Suwannarach, CMUB 40067 ( Holotype, preserved in a metabolically inactive state. Ex-type living culture LC 05-1 = SDBR-CMU 502 ) GoogleMaps .

Cultural characteristics.

Colonies on different agar media were incubated in the dark at 25 ° C for 2 months; colonies flat, irregular, with edge undulate, velvety; on PDA ( 18 to 27 mm in diameter) surface grayish brown, light brown at the margin, reverse olivaceous black, light brown at the margin; on MEA ( 18 to 23 mm in diameter) surface grayish brown, dark brown to black at the margin, reverse olivaceous black, producing brown pigment in agar; on OA ( 17 to 23 mm in diameter) surface grayish brown, reverse olivaceous black, sporulation absent; on PCA ( 17 to 20 mm in diameter) surface and reverse brownish gray, reverse olivaceous black, sporulation absent. On CMD ( 15 to 20 mm in diameter) surface and reverse grayish brown; and on CMA ( 20 to 27 mm in diameter) surface and reverse brownish grey, sporulation absent. Asexual morph in vitro dematiaceous hyphomycetes. Hyphae 1–2.5 µm wide, pale brown, simple to branched, septate, smooth, thin-walled, coiling, anastomosis observed. Conidiophores (10 –) 20–111 (– 153) × (1.4 –) 1.8–2.6 (– 2.9) µm ( x ̄ = 53.17 × 2.15, n = 40), macronematous, monomematous, straight or slightly flexuous, unbranched, continuous or 1–3 septate, dark brown, paler terminally, smooth-, thick-walled. Conidiogenous cells (6.6 –) 15.5–36 (– 45.5) × (1.4 –) 1.8–2.6 (– 2.9) µm ( x ̄ = 25.5 × 2.16, n = 40), integrated, polyblastic, terminal to mostly intercalary, proliferating sympodial and producing conidia from short denticles, subcylindrical, pale brown to brown, fertile parts subhyaline; denticles scattered, slightly darkened, 0.4–1 µm wide. Conidia (2.5 –) 2.8–4.4 (– 5) × (1.8 –) 2–3.3 µm ( x ̄ = 3.72 × 2.68, n = 40), abundant, obovoid or subglobose, with a round apex, and slightly truncate base, aseptate, subhyaline to pale brown, smooth-walled, with inconspicuous conidial scars, 0.5–1 µm wide. Chlamydospores rare, solitary or in chains, terminal, globose to pyriform, without or one-septate, pigmented, dark brown, smooth-, thick- walled. Sexual morph unknown.

Cardinal temperatures for growth on MEA after two weeks

(mm). Optimum at the range of 25 ° C to 30 ° C (10 to 14). No growth 4 ° C and 35 ° C.

Additional materials examined.

Thailand • Chiang Mai Province, Chai Prakan District, Nong Bua Subdistrict , endolichenic from the medulla of foliose lichen ( Parmotrema sp. ) on Prunus domestica , 19°42'23"N, 99°1'32"E, elevation 1160 m, 2 June 2023, C. Senwanna and N. Suwannarach, living culture (LC 05-3 = SDBR-CMU 503 ) GoogleMaps .

Additional GenBank numbers.

act and tef 1 for SDBR-CMU 502 : PQ 523738 and PQ 523739; tef 1 for SDBR-CMU 503 : PQ 523740.

Ecology and distribution.

Endolichenic fungi from the medulla of foliose lichen ( Parmotrema sp. ) in Thailand.

Notes.

Based on a blast search of the NCBI’s GenBank nucleotide database of the ITS sequence, Atrokylindriopsis racemosospora has the closest match with At. setulosa (strain HMAS 245592 ; KP 337330, ex-type) with 99.33 % similarity and is similar to Aciculomyces restrictus (strain FMR 18994 ; ON 009870 View Materials , ex-type) with 93.79 % similarity (identities = 468 / 499, 10 gaps) and Exophiala siamensis (strain SDBR-CMU 417 ; NR _ 184988, ex-type) with 92.39 % similarity (identities = 583 / 631, 16 gaps). The closest matches using the LSU sequence are At. setulosa (strain HMAS 245592 ; KP 337329) with 100 % similarity (identities = 548 / 548, 0 gap), Ex. ramosa (strain FMR 18632 ; ON 009933 View Materials , ex-type) with 98.97 % similarity (identities = 865 / 874, 1 gap), and Melanoctona tectonae (strain MFLUCC 12-0389; NG _ 059687) with 98.43 % similarity (identities = 879 / 893, 2 gaps). The closest matches using SSU sequence are Ex. siamensis (strain SDBR-CMU 417 ; ON 555826 View Materials ) with 99.53 % similarity (identities = 1055 / 1060, 1 gap), Capronia dactylotricha (strain CBS 604.96; NG _ 062636) with 98.45 % similarity (identities = 1082 / 1099, 1 gap), and E. yunnanensis (strain YMF 1.06739, ex-type) with 98.31 % similarity (identities = 1049 / 1067, 1 gap). The closest matches using the tub 2 sequence are Biscogniauxia arima (strain YMJ 122; AY 951672 View Materials ) with 93.08 % similarity (identities = 121 / 130, 1 gap) and B. mediterranea (strain ISN 9 LDC 31; OQ 942633) with 92.37 % similarity (identities = 121 / 131, 1 gap).

A combined multilocus-based phylogenetic analysis showed that both strains ( SDBR-CMU 502 and SDBR-CMU 503 ) of Atrokylindriopsis racemosospora formed sister taxon to At. setulosa ( HMAS 245592 , ex-type strain) with 100 % ML and 1 PP statistical support, and also clustered with Aciculomyces restrictus ( FMR 18994 , ex-type strain) with 95 % ML and 1 PP statistical support (Fig. 1 View Figure 1 ). The ITS and LSU nucleotide sequence comparisons reveal 3 / 580 and 0 / 548 base pair differences with At. setulosa , respectively. In contrast, a comparison of ITS, LSU, tef 1, and tub 2 base pairs shows that At. racemosospora differs from Ac. restrictus by 34 / 494 bp of ITS, 8 / 770 bp of LSU, 38 / 158 bp of tef 1, and 108 / 430 bp of tub 2. The morphology of Atrokylindriopsis differs from that of Aciculomyces in having unbranched, macronematous conidiophores, monophialidic conidiogenous cells, pigmented, septate, setulate conidia ( Ma et al. 2015; Torres-Garcia et al. 2023). Atrokylindriopsis racemosospora shares similar features, including sympodial proliferation, denticulate conidiogenous cells, and aseptate, obovoid or subglobose conidia, with species Ac. restrictus ( Torres-Garcia et al. 2023) , but Ac. restrictus has longer conidiophores (10–153 × 1.4–2.9 µm vs 19–105.5 × 1.5–2.5 µm) and smaller conidia (2.5–5 × 1.8–3.3 µm vs 2–4 × 1.5–2.5 µm). Moreover, the conidiogenous cells and conidia formation of At. racemosospora is more abundant than that of Ac. restrictus , and the conidial scars are not conspicuous. In addition, At. setulosa differs from At. racemosospora by its larger, cylindrical to clavate or rounded-cuboid conidia, which have 4–5 longitudinal eusepta and are attached to the conidiogenous locus at the midpoint of their long side, appearing to form a ‘ T’ ( Ma et al. 2015). These morphological characteristics clearly distinguish At. racemosospora from Ac. restrictus and At. setulosa .