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Seifert, K.A.; Hughes, S.J. 2000: Spiropes dictyosporus, a new synnematous fungus associated with sooty moulds. New Zealand Journal of Botany 38(3): 489-492.

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Seifert, K.A.; Hughes, S.J. 2000: Spiropes dictyosporus, a new synnematous fungus associated with sooty moulds. New Zealand Journal of Botany 38(3): 489-492.
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OTHER MATERIAL EXAMINED: NEW ZEALAND: AUCKLAND: Mangorewa Gorge, on. Euantennaria mucronata on Weinmannia racemosa, S. J. Hughes, 20 Mar 1963, DAOM 96767b; Rangemore Track, Waiatarua, Waitakere Range, on Capnokyma corticola on Olearia rani, S. J. Hughes, 8 May 1963, DAOM 143997,97045b.
Vegetative hyphae intimately associated with effuse or compact colonies of sooty moulds, cylindrical, pale to dark brown, sparingly branched, with occasional anastomoses, 3-3.5 µm wide, and septate at 8-27µm intervals; appressed to host hyphae, sometimes enveloping them or mixed with those of synnematous hosts. Synnemata 500-700 µm tall, emerging from superficial hyphae on the host plant, or arising from the ends of synnematous Antennatula conidiomata of Euantennaria sp. and then with broad host hyphae (10-20 µm wide) visible in the centre of the stipe, or from the surrounding bark or wood, lacking a basal stroma or tomentum, the stipe dark brown to black, cylindrical and 10-55 µm wide, smooth, unbranched or sometimes with a single branch, expanding into a divergent flat or slightly convex capitulum 50-200 µm wide. Hyphae of stipe 3-3.5(-6.5) µm wide, brown, with smooth walls unevenly thickened up to 0.5 µm, and simple septa thinner than the lateral walls. Conidiophores unbranched and continuations of the hyphae of the stipe or with one lateral branch. Conidiogenous cells polyblastic, 14.5-22.5 µm long, 3.5-5µm wide, straight, cylindrical but often uneven in diameter, with the walls unevenly thickened up to 0.5 µm; with 5 or 6 un pigmented scars per cell, about 2.5 µm diam. and 0.5 µm thick, with a central pore less than 0.5 µm diam.; successive sympodial but rectilinear proliferations of the conidiogenous cell rupture an outer wall layer around each scar. These result in the lateral displacement of scars and the presence of inconspicuous circumferential fringes of the torn wall 4-13 µm apart. Scars are relatively inconspicuous in face view but give the conidiogenous cells a scurfy texture in side view. Conidia brown, smooth-walled, ellipsoidal or slightly obclavate, sometimes slightly curved or sinuous or with a central constriction, dictyoseptate or sometimes phragmoseptate, with 3-7(-8) transverse or oblique septa, 1-5 longitudinal or oblique septa, (15-) 20-25(-35) x 6-9(-10) µm (x = 19.6 ± 0.5 x 7.4 ± 0.1 for conidia with 3-transverse septa, 22.3 ± 0.3 x 7.6 ± 0.1 for conidia with 4-transverse septa, 24.0 ± 0.6 x 7.6 ± 0.3 for conidia with 5-transverse septa (n = 10)), L/B c. 2.1-3.6, walls about 0.5 µm thick, the terminal cell rounded, usually slightly less pigmented and sometimes with a thinner wall at the apex, the basal cell somewhat flattened with an unpigmented scar about 2.5-3 µm wide and 0.5-1 µm thick. Conidia at first globose, thin-walled, expanding to ellipsoidal to nearly full size without septa, or becoming septate during expansion while still attached to the conidiogenous cell. Conidia germinate usually by a single, subhyaline germ-hypha from top of the apical cell, or sometimes just above the detachment scar.
Coloniae effusae; mycelium superficiale ex hyphis levibus cylindricis, raro ramosis, pallide brunneis vel atrobrunneis, 3-3.5 µm crass. compositum. Conidiomata synnematica, fusca vel atra, 500-700 µm alta, stipites 10-50 µm lat., leves. Hyphae stipitis 3-3.5(-6.5) µm crass., brunneae. Capitulum expansum, Conidiophora non vel raro uniramosa. Cellulae conidiogenae 14.5-22.5 x 3.5-5 µm, polyblasticae, rectae, sympodialiter proliferentes, cicatrices inconspicuae, primo apicalis, denique lateralia, 2.5 µm diam. Conidia sicca, brunnea, ellipsoidea vel subclavata, apice rotundata, (15-)20-25(-35) x 6-9(-10) µm, 3-8 transverse vel oblique septata, 1-5 longitudinaliter vel oblique septata.
HOLOTYPUS: In conidiomatis Euantennariae mucronatae in Weinmanniae racemosae, New Zealand, Wellington District, Tongariro National Park, Ohakune, leg. S. J. Hughes, 6.111.1963, DAOM 96772 (PDD 21037, isotypus).
Spiropes dictyosporus is characterised by the production of dark synnemata with smooth stipes on colonies of euantennariaceous sooty moulds (Dothideales), polyblastic conidiogenous cells with inconspicuous, laterally displaced scars sometimes separated by inconspicuous fringes, and dematiaceous dictyoconidia 20-35 x 6-10 µm. It is distinguished from all hitherto described species of the genus by its dictyoseptate conidia. It shares with other Spiropes species the following characters: dematiaceous, synnematous conidiomata, sympodially proliferating polyblastic conidiogenous cells with unpigmented, inconspicuous scars, and a lifestyle parasitic or consociant on predominantly foliicolous meliolaceous and other ascomycetes (Ellis 1968, 1971). Inconspicuous circumferential fringes on the outer wall of the conidiogenous cells have been observed in some, but not all, Spiropes species.
Four other similar genera were considered for the disposition of this species. Sclerographium includes four foliicolous and one bambusicolous species with dematiaceous synnemata, polyblastic conidiogenous cells lacking the inconspicuous circumferential fringes, and dictyoconidia (Hughes 1951; Ellis 1971). Species of Pseudospiropes are also somewhat similar to the new species but the dematiaceous conidiophores are not aggregated into synnemata, the scars are often darkened and conspicuous, and the species occur on dead wood, bark, and decaying herbaceous material (Ellis 1971). The oblique septa so characteristic of the conidia of S. dictyosporus are also seen in Dactylosporium macropus (Ellis 1971) but this species, which grows on fallen branches and dead herbaceous material, also does not produce synnemata. Dictyospiropes zizyphi has obclavate, beaked, distinctly muriform conidia that leave large, dark scars on the mononematous conidiophores.
We have classified our species in Spiropes primarily because of the apparent mycoparasitic habit and the characteristic proliferation of the conidiogenous cells, both characters of other known species of Spiropes that are absent in the other mentioned genera. Because no other species of Spiropes is known to have dictyoseptate conidia, we propose emendation of the generic diagnosis given by Ellis (1968, 1971) to include species with such conidia.
HOLOTYPE: On Euantennaria mucronata on Weinmannia racemosa. New Zealand, Wellington District, Tongariro National Park, Ohakune, S. J. Hughes, 6 Mar 1963, DAOM 96772; isotype: PDD 21037.

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18 March 2001
11 April 2005
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