Phyllactinia passiflorae-adenopodae R. Gregorio-Cipriano, D. González & Ramos, 2025

Gregorio-Cipriano, Rosario & Ramos, Antero, 2025, Phyllactinia passiflorae-adenopodae, and Phyllactinia sennae (Erysiphaceae), two new powdery mildew species found in Mexico, Phytotaxa 711 (2), pp. 183-194 : 186-188

Phyllactinia passiflorae-adenopodae R. Gregorio-Cipriano, D. González & Ramos , sp. nov. ( Figs. 2–3 ).

MycoBank: 856059

Diagnosis: Phyllactinia passiflorae-adenopodae is characterized by having falciform to asymmetrically ellipsoid-ovoid or lanceolate-ellipsoid conidia, not seen in any other previously described Phyllactinia species.

Etymology: Epithet derived from the name of its host, Passiflora adenopoda .

Holotype — MEXICO, Veracruz, Naolinco, on Passiflora adenopoda ( Passifloraceae ), 1530 m elev., 19°39’19.10”N, 96°52’53.28”W, February 19, 2020, Gregorio 686 (XAL); Isotype EBUM 28790. GenBank accession number: PQ427271 (ITS).

Description: Mycelia internal and external, external mycelium hypophyllous, in small or moderately large thin patches, whitish, almost imperceptible to the naked eye; often causing yellowish discolorations on the adaxial leaf surface. Superficial hyphae sinuous to almost geniculated, 4–9 µm wide, septate, thin-walled, smooth. Hyphal appressoria solitary or in opposite pairs, short cylindrical, straight to hooked or ramified in two or four lobes, sometimes nipple-shaped, (3–)4–24 × 3–13(–16) µm. Conidiophores arising from superficial hyphae, solitary, sometimes two on top of each mother cell, erect, straight throughout or curved-sinuous at the very base, 100–226 µm long (without conidia), frequently ramified into two or three conidiophores arising from near the top of foot cell. Foot cells cylindrical to subcylindrical, 58–198 × 7–9(–11.5) µm, followed by 1–2(–3) short cells, sometimes the first cell about same or slightly longer than foot cell; basal septum usually elevated, 7–15 µm long, portion between junction with the supporting hypha curved or sinuous, rarely straight. Conidia solitary, not evidently dimorphic; very variable, falciform to asymmetrically ellipsoid-ovoid or ellipsoid-lanceolate attenuated to the ends, apex rounded, or rarely pointed or apiculate, occasionally base side narrowly elongated; rarely ellipsoid to roboid with prominent narrowed obtuse ends, (37)39–64(–68) × (14–)17–29(–31) µm; germination tube near the base (8–10 µm) lobed or not. Teleomorph not found.

Additional Material examined:— MEXICO, Veracruz, Coatepec, on P. adenopoda , 1324 m elev., 19°30'45.90"N,

96°56'41.12"W, February 24, 2020, Gregorio 692 (XAL). GenBank accession number: PQ427272 (ITS).

Comments: — Ph. passiflorae-adenopodae is the first powdery mildew species found on a member of genus Passiflora in Mexico ( Table 3). Among the powdery mildews infecting Passiflora spp. around the world, there are two species of Phyllactinia , Ph. cruchetii Bolay & U. Braun on Passiflora caerulea L. in Switzerland ( Bolay et al. 2021), and Ovulariopsis passiflorae Syd. on Passiflora spp. , distributed in South Africa, South America ( Dominican Republic, Venezuela), and Asia ( India) ( Braun & Cook 2012).

Figures

FIGURE 2. Phyllactinia passiflorae-adenopodae on Passiflora adenopoda. A–B Conidia, C Conidium germination, D–E Conidiophore. Bars = 20 µm.

FIGURE 3. Phyllactinia passiflorae-adenopodae. A Conidia, B Conidiophores, C Hyphal appressoria. Bars = 10 µm.