Octospora conidiophora Sochorova & Doebbeler

Sochorova, Zuzana, Doebbeler, Peter, Sochor, Michal & Rooy, Jacques van, 2019, Octosporaconidiophora (Pyronemataceae) - a new species from South Africa and the first report of anamorph in bryophilous Pezizales, MycoKeys 54, pp. 49-76 : 53-62

Octospora conidiophora Sochorova & Doebbeler sp. nov. Figs 3, 4, 5, 6, 7, 8, 9

Etymology.

Conidiophorus (Gr./Lat.) refers to production of conidia.

Diagnosis.

Differs from Octospora kelabitiana by larger apothecia with a distinct margin, infection of pleurocarpous mosses of the family Sematophyllaceae and frequent formation of a Spermospora -like anamorph.

TYPE: SOUTH AFRICA. KwaZulu-Natal Province: Uthukela District Municipality, uKhahlamba Drakensberg Park, Injasuti, 29°7.72'S, 29°25.27'E, 1750 m alt., on Trichosteleum perchlorosum on decaying wood, 2 Mar. 2018, Z. Egertová (So chorová) and M. Sochor ZE48/18, holotype: PRM 951743, isotype: M; LSU GenBank accession number: MK569321, SSU GenBank accession number: MK569351, EF1α GenBank accession number: MK569297.

Description.

Apothecial features : Apothecia in groups on plants of Trichosteleum perchlorosum or Sematophyllum brachycarpum or between them, 0.2-1.5 mm broad, up to 0.65 mm high, first subglobose with a small apical opening, later hemispherical, turbinate to disc-shaped, pinkish-orange, sessile, mostly with a well-developed margin, outer surface of excipulum with adpressed to shortly protruding hairs or hyphae.

Hairs *55-205 × 4-10.5 µm, scattered at flanks, hyaline, scarcely septate, obtuse, thick-walled, wall *0.5-3.5 µm thick. Excipulum at the base *230-330 µm thick, laterally about 50 µm thick, composed of angular to subangular (triangular, trapezoid, rectangular), globose, subglobose or irregularly shaped cells, *6-43 × 5-42 µm, outermost cells thick-walled (neighbouring cells divided by up to *6 µm broad wall). Margin *60-280 µm broad, consisting of globose, subglobose, pyriform or trapezoid cells, *10-38 × 7-30 µm.

Subhymenium *40-75 µm wide, consisting of densely packed cylindrical cells *3-7 µm wide mixed with angular or irregularly shaped cells, *4.5-8 × 4.5-6 µm. Paraphyses filiform, straight or bent, unbranched, septate, uppermost one or two cells containing little very pale droplets (*0.5-2 µm in diameter), *2.1-3.5 µm broad (†1.5-2.3 µm), terminal cell *19-83 × 3-7 µm (†18-57 × 3-5.5 µm). Asci *146-197 × 12-15.5 µm (†135-192 × 9.5-12.5 µm), cylindrical, unitunicate, operculate, inamyloid, aris ing from croziers, with 8 uniseriate ascospores. Ascospores *13-17.2 × 7-10.5 µm, mean 15.2 × 9 µm, Q = 1.34-1.99, Qm = 1.69 (†13-17 × 7.5-10.5 µm, mean 15.2 × 8.5 µm, Q = 1.39-2.08, Qm = 1.79), ellipsoid to narrowly ellipsoid, hyaline, containing one or two lipid guttules (up to *8 µm in diameter if one, *4-5.5 µm if two), smooth or ornamented with cyanophilous, very small, obtuse warts 0.1-0.3 µm broad; germinating with a single germ tube.

Mycelial (†): Hyphae restricted to the lowermost plant parts, irregularly growing on and between the leaf bases, stems and especially the rhizoids, hyaline, with ramifications and anastomoses, often thick-walled, (2 –)3–6(– 7) µm in diameter (excluding ornamentation); hyphal surface with minute to large protuberances, in optical section with numerous minute or larger, semi- or subglobose warts or spines, in surface view, these structures sometimes looking like ridges extended perpendicularly to the hyphal axis; largest warts up to 1.5(-2) µm high; hyphae growing within hyphae present; whole hyphal wall slightly cyanophilous, outermost rough part strongly cyanophilous.

Appressoria variable, frequent (even more than 30 per leaf observed) and easy to detect, closely attached to both leaf sides or to rhizoids, colourless, 1-, 2- or 3-celled, from above elliptical, (14 –)16–23(– 26) µm long, (8 –)11– 16 µm wide, laterally seen slightly kidney-shaped, (7 –)9–13(– 16) µm high, with walls up to 2.5(-4) µm thick; surface rough but not warty, cyanophilous; appressorial cytoplasma strongly cyanophilous; appressoria mostly laterally formed on short stalks; stalks often gradually expanding toward the appressorium; perforation of the host cell wall by means of a delicate peg; peg often surrounded by a brown, straight or curved lignituber-like swelling measuring up to 10(-15) × 2 –4(– 6) µm; rhizoid wall at the perforation point slightly uplifted towards the appressorium; perforation point not always visible from above.

Haustoria within living leaf cells or rhizoidal cells, at first as a thick short filament, later becoming up to 55 µm long, orientated longitudinally in the rhizoid and developing ramifications (in wider rhizoids), rarely filling out the whole host cell; haustorial cytoplasm strongly cyanophilous.

Anamorph (†): Conidia variable in shape and size, claviform, hyaline, transversely septate, ca. (50 –)70–115(– 154) µm long (including the tail); proximal cell usually distinctly wider than the subproximal cell, rarely cells almost cylindrical, both cells measuring together (30 –)35–48(– 55) × (6 –)7.5–12(– 15) µm, subproximal cell continuously attenuating into a tail; tail typically curved to curled, 1- or 2-(3-)celled, (15 –)30–60(– 100) µm long and (1.5 –)2(– 2.5) µm in diameter at the distal end; proximal cell of the conidia with a conspicuous, circular, slightly protruding, delicately fringed scar, (3 –)4(– 4.5) µm in diameter, resulting from detachment from the conidiogenous cell; scar sometimes slightly laterally positioned; walls of conidia cyanophilous; the two proximal cells smooth, the tail sometimes warty (like the hyphae); germ tube one (to three) per conidium, arising from the scar or laterally from different regions of the conidia, including the tail cells.

Conidiogenous cells irregularly shaped, shorter and wider than sterile hyphal cells, rich in cytoplasmic content, usually with 1(-2) scars; shape and size of the scars like those at the conidia, also with a delicately fringed margin.

Hosts.

Trichosteleum perchlorosum , Sematophyllum brachycarpum ( Sematophyllaceae , Hypnales )

Distribution.

South Africa, Mpumalanga and KwaZulu-Natal Provinces (Fig. 8).

Conservation status.

Octospora conidiophora seems to be a common representative of the genus in South Africa, widespread and forming abundant populations. Its hosts are also common and widespread in the region (see below). Although the main habitat (afromontane forest) is naturally fragmented, it is often protected against human activities by nature reserves or national parks. Therefore, O. conidiophora does not fulfil the criteria for categories CR (critically endangered) to NT (near threatened) and we propose its evaluation as LC (least concern) for the present moment.

Additional specimens examined.

South Africa. Mpumalanga Province: Ehlanzeni District Municipality, Graskop Gorge, 24°56.74'S, 30°50.8'E, 1355 m alt., on Trichosteleum perchlorosum on decaying wood, 6 Mar. 2018, Z. Egertová and M. Sochor ZE62/18 (PRM 951745); Ehlanzeni District Municipality, Graskop Gorge, 24°56.88'S, 30°50.75'E, 1435 m alt., on Trichosteleum perchlorosum on decaying wood, 6 Mar. 2018, Z. Egertová and M. Sochor ZE63/18 (PRM 951746); Ehlanzeni District Municipality, Buffelskloof Nature Reserve, 25°15.98'S, 30°31.08'E, 1725 m alt., on Trichosteleum perchlorosum on decaying wood, 10 Mar. 2018, Z. Egertová and M. Sochor ZE75/18 (PRM 951748); Ehlanzeni District Municipality, Buffelskloof Nature Reserve, 25°16.37'S, 30°30.62'E, 1605 m alt., on Trichosteleum perchlorosum on decaying wood, 9 Mar. 2018, Z. Egertová and M. Sochor ZE71/18 (PRM 951747); Ehlanzeni District Municipality, Buffelskloof Nature Reserve, 25°16.53'S, 30°30.25'E, 1625 m alt., on Trichosteleum perchlorosum on decaying wood, 10 Mar. 2018, Z. Egertová and M. Sochor ZE77/18 (PRM 951749). KwaZulu-Natal Province: Uthukela District Municipality, Royal Natal National Park, 28°40.88'S, 28°55.73'E, 1760 m alt., on Sematophyllum brachycarpum on decaying stem, 19 Feb. 2018, Z. Egertová and M. Sochor ZE11/18 (PRM 951739); Uthukela District Municipality, Royal Natal National Park, 28°44.05'S, 28°54.85'E, 1800 m alt., on Trichosteleum perchlorosum on decaying stem, 20 Feb. 2018, Z. Egertová and M. Sochor ZE23/18 (PRM 951740). Uthukela District Municipality, uKhahlamba Drakensberg Park, Injasuti, 29°8.95'S, 29°25.35'E, 1665 m alt., on Trichosteleum perchlorosum on decaying wood, 3 Mar. 2018, Z. Egertová and M. Sochor ZE57/18 (PRM 951744); Uthukela District Mu nicipality, uKhahlamba Drakensberg Park, Giants Castle Nature Reserve, 29°16.93'S, 29°30.93'E, 1765 m alt., on Trichosteleum perchlorosum on decaying wood, 1 Mar. 2018, Z. Egertová and M. Sochor ZE46/18 (PRM 951742); Uthukela District Mu nicipality, uKhahlamba Drakensberg Park, Giants Castle Nature Reserve, 29°16.98'S, 29°30.87'E, 1775 m alt., on Trichosteleum perchlorosum on decaying wood, 1 Mar. 2018, Z. Egertová and M. Sochor ZE45/18 (PRM 951741).

Data to other lineages.

Lineage B: Mpumalanga Province: Ehlanzeni District Municipality, 3040 m WSW from the Graskop railway station, 24°56.28'S, 30°48.65'E, 1495 m alt., on Trichosteleum perchlorosum on decaying wood, 7 Mar. 2018, Z. Egertová and M. Sochor ZE65/18 (PRM 951735). KwaZulu-Natal Province: Uthukela District Municipality, uKhahlamba Drakensberg Park, Injasuti, 29°7.62'S, 29°25.33'E, 1725 m alt., on Trichosteleum perchlorosum on decaying wood, 2 Mar. 2018, Z. Egertová and M. Sochor ZE51/18 (PRM 951732); Uthukela District Municipality, uKhahlamba Drakensberg Park, Injasuti, 29°7.57'S, 29°25.38'E, 1715 m alt., on Trichosteleum perchlorosum on decaying wood, 2 Mar. 2018, Z. Egertová and M. Sochor ZE52/18 (PRM 951733); Uthukela District Municipality, uKhahlamba Drakensberg Park, Injasuti, 29°7.98'S, 29°26.25'E, 1500 m alt., on Trichosteleum perchlorosum on decaying wood, 2 Mar. 2018, Z. Egertová and M. Sochor ZE53/18 (PRM 951734); Sisonke District Municipality, Marutswa Forest, 29°48.55'S, 29°47.28'E, 1465 m alt., on Sematophyllum brachycarpum on decaying stem, 24 Feb. 2018, Z. Egertová and M. Sochor ZE37/18 (PRM 951730); Sisonke District Municipality, Marutswa Forest, 29°48.6'S, 29°47.37'E, 1480 m alt., on Trichosteleum perchlorosum on decaying stem, 24 Feb. 2018, Z. Egertová and M. Sochor ZE38/18 (PRM 951731).

Lineage C: KwaZulu-Natal Province: Uthukela District Municipality, uKhahlamba Drakensberg Park, Giants Castle Nature Reserve, 29°17.02'S, 29°30.87'E, 1780 m alt., on Sematophyllum brachycarpum on decaying wood, 28 Feb. 2018, Z. Egertová and M. Sochor ZE44/18 (PRM 951736); Uthukela District Municipality, uKhahlamba Drakensberg Park, Injasuti, 29°8.33'S, 29°25.68'E, 1565 m alt., on Sematophyllum brachycarpum on decaying wood, 3 Mar. 2018, Z. Egertová and M. Sochor ZE56/18 (PRM 951737).

Lineage D: Mpumalanga Province: Ehlanzeni District Municipality, Buffelskloof Nature Reserve, 25°16.93'S, 30°30.45'E, 1470 m alt., on Sematophyllum brachycarpum on decaying wood, 9 Mar. 2018, Z. Egertová and M. Sochor ZE69/18 (PRM 951738).

Taxonomic affinities.

The phylogenetically closest and phenotypically most similar species is Octospora kelabitiana described from Borneo, which shares most characters with the African species. It also has apothecia with stiff, thick-walled hyaline hairs, ellipsoid, hyaline ascospores of similar size like O. conidiophora († in H2O (13.5)14.5-17(18) × 7-8(9) μm, in LPCB (12.5)13-16(17) × (6.5)7-8(8.5) μm), filiform, unbranched paraphyses, smooth appressoria of similar size and even the warted mycelial hyphae, which is a character unknown in any other species of bryophilous Pezizales ( Egertová et al. 2018). Nevertheless, it can be distinguished easily by growth on a completely different host - thallose liverworts from the genus Riccardia Gray. Furthermore, its apothecia are smaller, often taller than wide and lack a distinct margin. Its appressoria are usually one-celled, less often two-celled, while in O. conidiophora , two-celled appressoria are very common and even three-celled ones were found. Anamorph has not been detected in O. kelabitiana .