Metacapnodium moniliforme S. Hughes

Metacapnodium cf. moniliforme (L. R. Fraser) S. Hughes Fig. 11 Specimens examined. USA • Kauai’i, Pihea Trail, at the Pu’u O Kila lookout point, Alt: 1260 m, 22.1474°N, 159.6311°W, on leaves of Metrosideros cf. polymorpha, 23 April 2016, J. Dee, UBC F 33050, cultured as DAOMC 252865, CCCM F 128. GenBank accession numbers. ITS, OR 532924; SSU, PP 836272; LSU, PP 140680; ef 1 - α, OR 820948. Description. Subicula dark brown to black, effused, superficial. Mycelium of moniliform hyphae, hyphae pale brown to brown when mature, smooth to finely verrucose, with deep constrictions at septa. Hyphae erect, straight to curved, hyphal branches grow upwards, narrow towards their tips. Cells broader than long, subglobose to doliiform, 15–25 (– 28) µm wide, narrowing to 6–10 µm at hyphal tips. Sexual form unknown. Asexual forms. Capnobotrys – Differentiated conidiophores not observed. Conidiogenous cells in whorls or semi – whorled clusters at the sides or tips of moniliform hyphae, globose to subglobose, brown to dark brown, bearing denticulate scars where successive conidia budded out, then seceded. Conidia brown, smooth walled, allantoid, ovoid, or ellipsoid in shape, brown, smooth walled, sometimes cornute and inequilateral, with a single median or supramedial septum, not or only slightly constricted at septa. On leaves, conidia (9) – 10.8 – (14) + / – 1.7 × (5) – 7 – (10) + / – 1.8 µm, N = 15, Q = 1.57, proximal cell 6.5 + / – 0.8 × 7.0 + / – 1.84 µm; distal cell 4.3 + / – 0.96 × 5.9 + / – 2 µm. Proximal cells 1.57 × as long as distal cells and 1.2 × as wide. A few much larger, dark brown, verrucose, thick-walled conidia also present, 15–18 × 10–11 µm. Conidia in culture similar but slightly narrower, (8) – 10 – (12) + / – 1.0 × (5) – 5.8 – (7) + / – 0.6 µm, N = 30, Q = 1.8. Proximal cells longer and wider than distal cells; proximal cells 6.0 + / – 0.8 × 5.8 + / – 0.6 µm, distal cell 4.2 + / – 0.4 × 4.1 + / – 0.4 µm. Proximal cells from leaves and cultures sometimes with an inconspicuous, oblique scar resulting from secession from basal or diagonal attachment to a conidiogenous cell; distal cells bear an apical wall thinning, light brown in color, sometimes protruding to resemble a basidiospore’s hilar appendix. Capnophialophora – (Fig. 11 F, G) Phialides, found on leaves but not in cultures, on tips or sides of hyphae, with a light brown to brown, subspherical venter 4–6 µm wide; bearing a funnel – shaped collarette up to 3 µm long, constricted at its base and 2 µm wide at its opening. Host and distribution. Known only from leaves of Metrosideros cf. polymorpha from Hawaii. However, additional basic systematic research may place this slightly divergent specimen in M. moniliforme, a species with a broad host range. Notes. This specimen’s ITS sequence clusters with the other two M. moniliforme specimen sequences with 96 % or more bootstrap support but is 1.7 to 2.5 % different from the other M. moniliforme ITS sequences. Morphologically, it is similar to M. moniliforme. However, no Capnosporium form was observed.