AUTHENTIC SPECIMENS: Sri Lanka, Hakgala, on bark, May 1910, Petch 3145, K*; on twigs, Jan 1914, Petch 3941, K*; on bark, Sep 1908, Petch 2856, K*.
ADDITIONAL COLLECTIONS EXAMINED: NORTH ISLAND: AUCKLAND: Waitemata county, Waitakere Ranges, Walker's Bush, on unknown host, 13 Dec 1973, J. M. Dingley, PDD 32101. BAY OF PLENTY: Mamaku State Forest, unknown host, 22 Mar 1963, J. Gilmour, PDD 21685; GISBORNE: Urewera National Park, Lake Waikaremoana: on root of dead tree, 29 May 1983, G. J. Samuels, P. R. Johnston, T. Matsushima, & A. Y. Rossman, PDD 45803; on root of dead tree, 29 May 1983, G. J. Samuels, P. R. Johnston, T. Matsushima, & A. Y. Rossman, PDD 45804. NORTHLAND: South of Kaitaia, Omahuta State Forest, Omahuta Kauri Sanctuary, on Freycinetia banksii, 12 May 1981, G. J. Samuels & E. Horak, PDD 41969, anamorph on host, cultures on OA, CMD; vic. Mangamuka Bridge, Omahuta State Forest, Omahuta Kauri Sanctuary, on tree, 12 May 1981, G. J. Samuels & E. Horak, PDD 49960.

Subiculum persistent, brown to dark brown, wiry, appressed, with synnemata. Stromata (1250)1766 ± 330(2500) µm high, (1125)1740 ± 312(2250) µm wide (n = 30), globose to subglobose with almost flattened top, cupulate, often with a short cylindrical base immersed in the subiculum, copper brown, dark brown, black around the ostioles, smooth, solitary to crowded and laterally compressed. Ostioles finely to coarsely papillate. Ectostroma (75)100-125 µm thick, black. Entostroma white, confined to base. Perithecia detached and collapsed in mature material. Ascus apical ring (6.7)8.3 ± 0.8(9.6) µm high, upper width 5.7-6.2 µm, lower width 3.8-5.7 µm (n = 16), J+, dark blue. Ascospores (37.4)48.6 ± 4.2(58.5) µm long, (4.8)7.6 ± 0.8(9.6) µm wide (n = 167), inequilateral, narrowly ellipsoidal to needle shaped, with narrowly rounded ends, brown to dark brown, with straight, 8-12 µm long germ slit centred on the flat side, both extremities and flat side surrounded by a slimy sheath, 2-3 µm thick at ends, 1 µm thick at side. Synnemata up to 2000 µm, conidia 4-5 x 3-4 µm.
Culture on OA after 20 days under 12 h dark and 12 h UV and fluorescent light 7 cm diam., centre (3 cm) black from confluent tufts of black hyphae shaped as witches' brooms, otherwise white, hyphae very short, sterile. On CMD after 43 days under same conditions covering whole plate (9 cm diam.), black with cottony white margin. Synnemata profusely arising at the margin and on the original inoculum, 0.5-1 mm long, acute, unbranched, black, without stromatic base, composed of 3-4 µm wide smooth, brown, branching, septate hyphae, often sterile. Free conidiophores forming on one area of the original inoculum, long, heavily and irregularly branched. Conidiogenous cells 18-48 3-4 µm (n = 9), terminal, geniculate, smooth, subhyaline to pale tantowards the base. Conidia 3.5-5(7) x 2-3.5 µm (n = 22), forming at the tip of each synnema as loose, white-grey areas, oblong with flat, non-protuberant base bearing a minute frill being more refractive than the rest of the conidial wall, smooth, subhyaline.

HOSTS: Freycinetia baueriana subsp. banksii, unidentified wood.
MATRIX: Corticated twigs, roots.

NOTES: The New Zealand collections were compared with the Sri Lankan specimens of R. arcuata collected by Petch. The subiculum and the Dematophora anamorph as well as the ascospore shape and the short germ slit are identical. In addition, the statistical analyses revealed that there are no differences among the collections regarding quantifiable characters such as size of stromata, ascospores, or the ascus apical rings.
Macroscopically R. arcuata resembles R. necatrix Prill., but its ascospores are statistically significantly larger (Fig. 9A). Roger (1953) and Saccas (1956) reported R. arcuata among other host plants on roots of Camellia sinensis (L.) Kuntze and Coffea arabica L., damaging them severely. The stromata and ascospore sizes are similar to those reported for the New Zealand and the Petch specimens, but both authors describe a germ slit about twice as long. According to Saccas (1956) the geographical distribution of R. arcuata is confined to tropical and humid regions of Africa and Asia. In fact, the Petch specimens are from a mountainous region of Sri Lanka. In New Zealand, R. arcuata was mainly collected in the northern part of the North Island in national parks and state forests with subtropical vegetation and has not been reported from cultivated trees.
There are some specimens in PDD labelled as R. necatrix, with only the Dematophora anamorph present. They originate from Narcissus sp., Vitis vinifera L., Juglans regia, Malus sylvestris L., and Malus x domestica Borkh. (PDD 50725, PDD 49923, PDD 26403, PDD 17391, PDD 24985, respectively) and may be, indeed, R. necatrix, as these are typical hosts for this species. In fact, root diseases caused by R. necatrix were reported by Bösewinkel (1977) and are listed in the New Zealand Plant Disease Database. Most Rosellinia species reported as severe root pathogens have ascospores similar to those of R. arcuata or R. necatrix, slender with tapering ends, short germ slit, and slimy sheath, varying only in size. Molecular biological studies are needed to confirm or reject conspecificity for suchtaxa.
Rosellinia asperata Massee, R. bothrina Berk. & Broome, R. desmazieresii (Berk. & Broome) Sacc. var. acutispora Theiss., R. gigantea Ellis & Ever., R. pepo Pat., and R. puiggiari Pat. possess ascospores with a morphology similar to those of R. arcuata.
Examination of the type materials from the herbaria FH, K, NY, and PACA revealed that character combinations such as stroma shape and size and ascospore size do not match those of R. arcuata (L. E. Petrini unpubl. data).