Metacapnodium moniliforme S. Hughes

Metacapnodium moniliforme (L. R. Fraser) S. Hughes Fig. 10 Specimens examined. Usa • Hawaii, On Cheirodendron trigynum, Jun. 1990, C. Inada, DAOM 234317; Australia, New South Wales, on unidentified leaves, 17 Aug. 1999, K. Seifert, DAOM 226251. GenBank accession numbers. Collection DAOM 234317 (ITS, OR 532936); Collection DAOM 226251 (ITS, OR 532935). Description. Subicula dark brown to black, effuse, superficial on leaves or twigs, typically less than 1 cm in diameter although sometimes becoming confluent. Mycelium of moniliform hyphae. Hyphae pale brown to brown, when mature, finely verrucose, deep constrictions between cells. Hyphae are erect, curved, smooth to finely verrucose, branching, then growing upwards, narrowing towards their tips. Most cells as broad as or broader than long, subglobose to doliiform, when mature up to 21 µm wide, tip cells narrowing to 5 µm. Sexual form. Ascomata scattered, semi-immersed in subicula, dark brown, globose (immature), subglobose to obovoid, (50 –) 70–180 µm high and 50–120 µm wide, ostiolate, having straight to curved appendages (Fig. 10 K, L). Asci bitunicate, 8 – spored, ellipsoid to clavate, 50–70 × 12–25 µm. Ascospores irregular or biseriate within asci, ellipsoid, light brown to brown, mainly 3 (– 4) septate, (17) – 19.8 – (23) + / – 2.6 × (8) – 8.75 – (10) + / – 0.7 µm (DAOM 226251). Asexual forms. Capnobotrys – No distinctive conidiophores observed. Conidiogenous cells unilateral or in botryose clusters at 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, initially smooth walled, subglobose, elongating to become ellipsoid ovoid to allantoid, often cornute and inequilateral, with a single median or supramedial septum. Conidia (9) – 14 – (20) + / - 3.4 × (5) – 7.7 – (11) + / - 1.9 µm, Q = 1.8 (DAOM 226251) or (9) – 12.3 – (14.5) + / - 1.7 × (7) – 7.9 – (9) + / - 0.8 µm, Q = 1.6 (DAOM 234317, not illustrated). Proximal cells 8.0 + / – 1.9 × 7.7 + / – 1.9 µm, longer and wider than distal cells 6.1 + / – 1.2 × 6.3 + / – 1.9 µm. Proximal cells sometimes with inconspicuous, oblique scar from secession from basal or diagonal attachment to their conidiogenous cell. Distal cell with an apical patch of thinner, paler wall that sometimes protrudes, resembling the proximal hilar appendix of a basidiospore. Capnophialophora – Phialides single or in small clusters, with light brown to brown subspherical venters 4–6 µm wide, bearing a funnel-shaped collarette 2.5–4.5 µm long with a constriction at its base, 2–3 µm wide at its opening. Capnosporium – Rarely observed, but for examples of sizes, a conidium with two septa was 25 × 12 µm; one with three septa was 32 × 9 µm, and one with four septa was 36 × 12 µm (DAOM 226251). Hosts and distribution. Reported on small twigs and leaves of varied plants including ferns and dicots. Widely distributed according to Hughes (1981); known from New Zealand, Australia, Chile, and perhaps elsewhere if M. cf. moniliforme UBC F 33050 from Hawaii, and M. aff. moniliforme E 01043362 from Scotland could all be considered conspecific. Notes. The ITS phylogeny shows that the two specimens identified as M. moniliforme, DAOM 234317, DAOM 226251, M. cf. moniliforme UBC F 33050 (described below) and M. aff. moniliforme E 01043362 form a clade with 97 % bootstrap support (Fig. 2). The average sizes of the capnobotrys conidia varied with lengths from 10 to 14 µm. Hughes (1981) reported that conidia may almost double in length, walls becoming verrucose, at the time of germination. The M. moniliforme group and M. neesii appear as sister groups in trees from ITS, concatenated genes, and ef 1 - α, although without strong statistical support. Conidiogenous cells of capnobotrys in M. neesii and M. moniliforme are similar in shape, in arrangement, and in the oblique positioning of conidia on the conidiogenous cell. Conidia in both are 1 - septate. However, in M. neesii, the distal cell of a conidium is often less than half the length of the proximal cell (Hughes 1979) while in M. moniliforme, the distal cell is between 2 / 3 and 3 / 4 of the length of the proximal cell. According to Hughes (1981), the capnobotrys conidia of M. guava are smaller but otherwise similar in shape to those of M. moniliforme. However, sizes of conidia of M. guava given by Hughes (1981) fall within the range of sizes of conidia M. moniliforme measured here. Hughes (1981) suggested that M. guava capnobotrys conidia do not develop the cornute morphology seen in M. moniliforme. To resolve the differences between the two species, a combination of comparative morphology and barcode sequencing of additional collections would be useful.