2022 Volume 63 Issue 2 Pages 58-64
Black subicula, comprising a mixture of two sooty moulds of Euantennariaceae and Metacapnodiaceae, on Pleioblastus were collected in Batongguan, alt. ca. 2800 m, Nantou County, Taiwan in 1984. The former sooty mould is described and illustrated as Euantennaria pleioblasti sp. nov., an asexually typified species of the genus, as currently circumscribed with the application of the single name nomenclature for pleomorphic fungi. It is characterized by cylindrical, finely to coarsely roughened hyphae and black synnemata bearing massive fusiform, straight, mostly 11-14-septate phragmoconidia in a subglobose to obovoid head; its reliable sexual morph is obscure. The latter was identified as Metacapnodium cf. quinqueseptatum. It features the capnobotrys- and capnophialophora-like asexual morphs, in addition to the sexual morph with 5-7-septate ascospores. These sooty mould taxa are newly added to the mycobiota of Taiwan.
Members of the sooty mould families Euantennariaceae and Metacapnodiaceae, both erected by Hughes and Corlett in Hughes (1972), are well known to have highly morphological divergence in their asexual morphs (anamorphs) and are often mixed in a subiculum or colony on the same host plant (Hughes, 1976; Hughes & Seifert, 2012; Sugiyama & Hosoya, 2019). For example, Sugiyama and Amano (1987) described the co-occurrence of Capnobotrys neesii S. Hughes (now Metacapnodium neesii (S. Hughes) Sugiy. & Hosoya in Sugiyama, Nam, & Hosoya, 2020) and Capnobotryella renispora Sugiy. in Sugiyama and Amano (1987) (now classified in Teratosphaeriaceae Crous & U. Braun in Crous, Braun, & Groenewald, 2007) in a subiculum on living twigs of Abies veitchii. Other examples are the sooty mould colonies or subicula with distinctive hyphae of members of Metacapnodiaceae and Euantennariaceae illustrated in Fig. 1 by Hughes and Seifert (2012) and in Fig. 1A and Supplementary Fig. S2 by Sugiyama and Hosoya (2019). The hyphal morphology, sexual morph, and asexual morphs in Euantennariaceae and Metacapnodiaceae are distinctive and diagnostic (Hughes, 1972; 1976; Hughes & Seifert, 2012). The former family is characterized by more or less cylindrical hyphae with the cells usually longer than broad, a Dothidea type centrum, and the phragmoconidial and phialidic asexual morphs. On the other hand, the latter family is characterized by moniliform (barrel-shaped) hyphae with the cells generally broader than long, a Pleospora type centrum, and the sympodial, phialidic, tretic and arthric asexual morphs. A suite of these morphological characters is effective for the classification and identification of sooty moulds attributed to both families (e.g., Hughes, 1974, 1976, 1981; Hughes & Seifert, 2012).
In Jul 1984, Dr. Yoshimichi Doi (at that time affiliated with the National Museum of Science, Tokyo) collected sooty moulds occurring on the living branches with leaves of Pleioblastus sp. in Batongguan, at an altitude of approximately 2800 m, Nantou County, central Taiwan; the collection (Fig. 1A; Supplementary Fig. S1) was provided by the collector to the first author of this paper. His preliminary examination (Sugiyama, 1985) suggested the occurrence of two different pleomorphic sooty moulds in a mixed subiculum (Fig. 2B). Recently, after more detailed taxonomic research on the specimen and nomenclatural consideration, one sooty mould was characterized and is herein proposed as a new species of Euantennaria Speg. (Hughes, 1974; Sugiyama & Hosoya, 2020) in Euantennariaceae. Based on a detailed comparison with numerous authentic specimens, the other sooty mould was identified as Metacapnodium cf. quinqueseptatum (Metacapnodiaceae). The descriptions of these sooty moulds are provided below with illustrations and notes.
For microscopical examination, all or part of the subicula was observed under a stereomicroscope, either Nikon SMZ645 (Nikon, Tokyo, Japan) or Olympus SZ61 (Olympus, Tokyo, Japan). A small portion of the subiculum was carefully teased using two dissecting needles and mounted in Shear's mounting fluid (Gams, van der Aa, van der Plaats-Niterink, Samson, & Stalpers, 1987) on a microscopic slide under a steromicroscope. The slide preparations were examined with a Nikon Optiphot microscope equipped with phase contrast (PC) and differential interference (DIC) and photographed with an HFX photo system (Nikon) or examined with the BX51 microscope with DIC (Olympus) with a Nikon Digital Sight DS-Fi2-L3 (Nikon) photo system. The holotype specimen was deposited in the mycological herbarium of the National Museum of Nature and Science (acronym: TNS) in Tsukuba, Japan.
TaxonomyEuantennaria pleioblasti Sugiy. & Hosoya, sp. nov. Figs. 1, 2, 3,
Supplementary Figs. S1, S2.
MycoBank no.: MB 840641.
Diagnosis: Similar to the known species of Euantennaria having a monoblastic asexual morph that produces fusiform and straight phragmoconidia with 11-16 septa. However, it differs from the most closely related species Euantennaria katumotoi (Sugiy. & Hosoya) Sugiy. & Hosoya (≡ Antennatula katumotoi Sugiy. & Hosoya) especially by bearing the broader phragmoconidia, which are 10-14 μm wide, and lacking a characteristic bulbous swelling at the base and a phialidic asexual morph.
Type: TAIWAN, Nantou County, Batongguan, altitude approximately 2800 m, on living branches with leaves of Pleioblastus sp., 31 Jul 1984, coll. Yoshimichi Doi (TNS-F-88647, holotype).
Etymology: The specific epithet pleioblasti refers to the generic name of host plant, on which this sooty mould grows.
Subicula dark blackish brown to black, loosely to densely veltinous, thin or thick, loose or compact, up to 5 mm wide but much smaller, scattered, and frequently mixed with other sooty moulds.
Mycelium superficial, composed of septate cylindrical hyphae, brown to dark brown, finely to coarsely roughened throughout, sometimes anastomosing, straight or curved with the branching often at right angles. Hyphal cells generally longer than broad, slightly inflated, not or slightly constricted at the septa, thick-walled, 12-27 × 8-11(-14) μm. Plumose fascicles and synnemata emerge scattered on the surface of subicula; synemmata dark blackish brown to black, up to 2 mm tall and 70-150 μm thick (under dry conditions), sometimes bearing an apical subglobose or obovoid conidial head up to 300 μm high and 200 μm wide (under dry conditions); the fertile terminal cells of fasciculate hyphae 6-7.5 μm wide, with fine to conspicuous conidium scars.
Asexual morph (Figs. 1B, 2, 3; Supplementary Fig. S2): Distinctive conidiophores lacking. Almost all phragmoconidia develop singly from the apex, with a few fertile cells (up to 6) below the apex of the fasciulate synnematous hyphae, which bear massive conidia in a (presumably mucilaginous) subglobose or obovoid head; multiple (a few) conidium production from the apical cells of the fasciculate hyphae may occur, but frills on the outer wall of the conidiogenous cells (cf. Fig. 2 E-G in Hughes, 1974) and percurrent extensitions (annellations) inconspicuous or not seen. At maturity these conidia straight (or nearly straight) or slightly bent near the base, fusiform to narrowly ellipsoidal to cylindrical, smooth, thick-walled, not constricted at the septa, pale brown to brown, paler at the distal cells, and bluntly rounded at the apex and tapered toward the slightly flattened basal scar 2.5-3 μm wide at the base, with no basal swelling; these are transversely (8-)11-14(-15)-septate and measure 73-125 × 10-14 μm. The ranges in length and width of seceded conidia are as follows: (9-septate) 73-87 × 10-12 (81.6±5.46 × 11±1, average±s.d.; n=5); (10-septate) 75-93 × 10-12 (86.0±7.21 × 11±0.7; n=5); (11-septate) 85-110 × 10-14 (96.5±6.87 × 11.5±1.27; n=10); (12-septate) 98-120 × 10-14 (105.16±5.84 × 11.9±1.04; n=19); (13-septate) 98-120 × 10-13 (109.71±6.94 × 11.59±1.03; n=17); (14-septate) 105-125 × 10-13 (115.14±6.69 × 11.29±1.25; n=7). Conidia with 8-septa (87.5 × 12.5 μm) and 15-septa (118 × 13 μm) rare. The end cells of phragmoconidia may germinate to produce hypha. Expected phialidic morph, namely the hormisciomyces-like asexual morph, producing microconidia not observed.
Expected sexual morph (Supplementary Fig. S3): Scanty black to dark brown, subglobose ascomata were observed in the subicula. Asci obclavate, probably bitunicate. Ascospores fusoid, rounded at both ends, pale brown, smooth-walled, constricted at the septa, 3-septate, 14-18 × 5-7 μm (15.5±1.27 × 5.9±0.79 μm; n=10). The sexual morph could not be fully characterized based on morphological characters. Consequently, the true connection between the sexual morph (ascomata) and asexual morph (blastic phragmoconidia) remains unresolved.
Isolation: No attempt was made to isolate a culture because a few months had passed between the fungus collection and the author's examination of the specimen.
Habitat and distribution: On living branches with leaves of Pleioblastus sp. (Bambusoideae, Poaceae, monocotyledons) growing in the subalpine zone at the elevation of ca. 2800 m, Batongguan, Nantou County, central Taiwan.
Specimen examined: As described above in the typification.
Notes: The blastic asexual morphs of Euantennaria (type species: E. tropicicola Speg.) are primarily defined by their phragmoconidia (macroconidia), which develop blastically and singly from scattered cells of repent hyphae, and fusiform, straight to variously curved (sometimes sigmoid or strongly curved) and occasionally with a distinctly recurved apex, and transversely 3- to multi-septate (Hughes, 1974, 1976; Hughes & Seifert, 2012; Sugiyama & Hosoya, 2020). In E. mucronata (Mont.) S. Hughes, the commonest sooty mould from the southern Pacific Basin (Hughes, 1972, 1974; Map. 8.5 in Pirozynski & Weresub, 1979; Sivanesan, 1984; Sugiyama, Amano, & Yokoyama, 1984; Fig. 49 in Hyde et al., 2013; cf. Table 1 in Sugiyama & Hosoya, 2019), percurrent extensions (Seifert, Morgan-Jones, Gams, & Kendrick, 2011), recognized by the frills at the terminal conidiogenous cells in fasciculate synnematous hyphae, were detected infrequently by Hughes (Fig. 2 E-G in Hughes, 1974). A similar mode of conidiogenesis (conidium ontogeny) was seen in E. pleioblasti from the Taiwan specimen (Fig. 2E-G; Supplementary Fig. S2). The frills that indicate purcurrent extensions (annellations) are conspicuous in E. mucronata (Fig. 2 E-G in Hughes, 1974), whereas those of E. pleioblasti are lacking or inconspicuous (Fig. 2E-G; Supplementary Fig. S2). Otherwise, the two are easily distinguishable morphologically; the fusiform phragmoconidia in E. mucronata are usually curved (sometimes strongly recurved at the apex) and mostly 9- to 11-septate (Hughes, 1974; Sugiyama et al., 1984), whereas those of E. pleioblasti are straight and mostly 10 to 14-septate (this study). The differences between E. pleioblasti and related species are briefly discussed below.
Among the known species of Euantennaria with mostly ≧9-septate phragmoconidia, namely E. katumotoi (≡ Antennatula katumotoi), E. fraserae (S. Hughes) Sugiy. & Hosoya (≡ A. fraserae S. Hughes), E. lumbricoidea (Dearn.) Sugiy. & Hosoya (≡ A. lumbriocoidea (Dearn.) S. Hughes), and E. tropicicola (Table 1 in Sugiyama & Hosoya, 2019; cf. Sugiyama & Hosoya, 2020), E. pleioblasti is most similar to E. katumotoi occurring on Abies veitchii twigs from central Honshu, Japan with slenderly fusiform and straight, (7-)11-15(-18)-septate phragmoconidia measuring 75-128 × 8.5-10 μm, usually with a minute bulbous swelling at the base. However, the former is readily distinguished from the latter by the slightly broad (10-14 μm wide) fusiform, (8-)11-14(-15)-septate phragmoconidia measuring 73-125 μm long, with no characteristic bulbous swelling at the base.
As a result of the comparative examination of morphological characters, an asexually typified new species E. pleioblasti is proposed herein under the One Fungus-One Name (1F-1N) rule (Turland et al., 2018) for pleomorphic euantennariaceous sooty moulds.
Metacapnodium cf. quinqueseptatum (M.E. Barr) S. Hughes 1972 Fig. 1A,
Supplementary Figs. S1, S4, S5.
Subicula dark brown to black, superficial, effuse, scattered and mixed with other sooty moulds such as a Euantennaria.
Mycelium superficial, composed of brown to dark brown hyphae roughened throughout, sometimes anastomosing, septate, straight to flexuous, moniliform (doliiform). Hyphae markedly tapered toward their distal end cells as narrow as 6-10 μm wide. Individual hyphal cells usually as broad as or broader than long, 7-15 × 11-22(-33) μm.
Sexual morph (Supplementary Fig. S4): Ascostromata partly immersed, scattered, brown to dark brown, subglobose, bearing hyphal appendages; hyphal appendages simple, short, moniliform, brown to dark brown, straight, rounded at the apex; the size of ascostromata could not be determined. Asci bitunicate, broadly ellipsoidal to obclavate, 8-spored, up to 70 μm long and 30 μm wide. Ascospores ellipsoidal, rounded (not mucronate) at both ends, straight, sometimes non-equilateral, brown to dark brown, paler at their ends, smooth-walled, 5-7-septate, not constricted at the septa, 26-45 × 8-10 μm, with no gelatinous sheath. The ranges of length and width of seceded ascospores are as follows: 5-septate, 26-38 × 8-10 (32.5±4.93 × 9±0.89), n=6; 6-septate, 32-38 × 8-10 (35±2.58 × 8.75±0.96), n=4; 7-septate, 40-45 × 8-10 (42±2.16 × 9.25±0.96), n=4.
One asexual (sympodial) morph (Supplementary Fig. S5B-E): Characterized by the capnobotrys-like asexual morph. Distinct conidiophores lacking. Conidiogenous cells borne singly or in small clusters at the ends and along the sides of the undifferentiated moniliform (doliiform) hyphae; usually crowed, subglobose to broadly ellipsoidal, coarsely warted, brown to dark brown, short denticulate, 10-11.5 × 5.5-7 μm. Conidia produced blastically on successive new growing points, broadly ellipsoidal, 1-sepate almost in the middle, not or slightly constricted at the septum, somewhat thick-and smooth-walled, brown to dark brown, 12.5-16 × 7-11.5 μm.
Second asexual (phialidic) morph (Supplementary Fig. S5F, G): Characterized by the capnophialophora asexual morph. Distinct conidiophores lacking. Conidiogenous cells (phialides) produced singly or in irregular clusters of 2 to 4 at the apex and laterally on undifferentiated moniform (barrel-shaped) hyphae, flask-shaped with a subspherical, paler brown to brown, slightly warted venter (5.5-7 μm wide) and a single cupulate to funnel-shaped collarette up to 5 μm long and 2-3 μm wide. Microconidia (phialoconidia) not seen.
Isolation: No attempt was made to isolate a culture because a few months had passed between the fungus collection and the author examination of the specimen.
Habitat and distribution: As described above for E. pleioblasti.
Specimen examined: As described above in the typification for E. pleioblasti sp. nov.
Notes: The other sooty mould on Pleioblastus sp. from Taiwan was assigned to the sexually typified genus Metacapnodium Speg. [type species: M. juniperi (W. Phillips & Plowr.) Speg. (Hughes, 1981)], in the family Metacapnodiaceae Hughes & Corlett in Hughes (1972). The genus is now characterized by its moniliform (doliiform), roughened hyphae, transversely 3- or more (up to 11-) septate or dictyoseptate ascospores with conical end cells, and sympodial (capnobotrys) and phialidic (capnophialophora) morphs (Hughes, 1972, 1974; Sivanesan, 1984; Hughes, Atkinson, & Seifert, 2012; Hawksworth & Boluda, 2020; Sugiyama et al., 2020).
Among the known Metacapnodium species, the only species having 5-septate ascospores is M. quinqueseptatum (Sivanesan, 1984). This species was originally described by Barr (1955) as Limacinia moniliformis (as ‘moniliforma’) var. quinqueseptata Barr based on a single collection (DAOM 46165, type) on twigs of Pseudotsuga taxifolia from Vancouver Island, BC, Canada (see Supplementary List). Later, it was transferred by Hughes (1972) to Metacapnodium as M. quinqueseptatum (as ‘quinqueseptata’), and subsequently additional specimens were collected by Hughes on conifers (Psudotsuga, Tsuga, and Thuja) from the same locality in Jul and Aug 1972. The specimens were preserved in DAOM (Supplementary List of this paper; cf. Hughes, 1981). However, Sivanesan (1984) briefly re-described and illustrated M. quinqueseptatum, and the ericaceous angiosperms Acrostaphylos sensitiva and Acrostaphylos spp. (USA) were listed as its additional host plants.
The Taiwan collection (TNS-F-88647) is very similar to M. quinqueseptatum (Barr, 1955; Sivanesan, 1984) in having sympodial and phialidic morphs in addition to the sexual morph with ellipsoidal, 5-septate ascospores, but our careful observation of authentic specimens of M. quinqueseptatum (see Supplementary List) shows that the former is slightly different from the latter in producing 5-7-septate ascospores (Supplementary Fig. S4C, E, F). Further, the sympodial morph of TNS-F-88647 is characterized by the shape of its 1-septate conidia (Supplementary Fig. S5C-E). The brief description and Fig. 56 provided by Sivanesan (1984), in addition to a slide preparation and Hughes' annotation with his free-hand drawings on the packet of DAOM 46165 (type) (Supplementary List), show that these conidia are obovoid, non-equilateral, supramedially 1-septate (resulting in the lower cell about twice as long as the upper one), 10-16 × 9-12 μm. Therefore, the Taiwan collection differs from the type collection of M. quinqueseptatum in the position of the septum of 1-septate conidia, although their phialidic morphs are very similar. We therefore suggest a tentative identification, and describe the fungus as having close affinity with M. quinqueseptatum.
Here we would like to briefly discuss the synonyms of M. quinqueseptatum. Listed in both Species Fungorum (2021) and MycoBank (2021) are Massarina quinqueseptata M.E. Barr (Barr, 1992; Hyde, 1995), typified by W. B. Cooke & V. G. Cooke (MycoBank Typification #80645, Collectors number 60783B pro parte) in NY, on branches of Sambucus caerulea (Calif., USA) and Splanchnonema quinqueseptatum (M.E. Barr) Aptroot (Aptroot, 1998). These two species names should be eliminated from the synonymy of Metacapnodium quinqueseptatum because they have 5-septate ascospores with gelatinous coating (Fig. 2s in Barr, 1992) or a gelatinous sheath (Fig. 45 in Aptroot, 1998). Such features are not consistent with the generic and familial concept of Metacapnodium and Metacapnodiaceae (Hughes 1972, 1976, 1981). In addition to these, the host plants Acrostaphylos sensitiva and Acrostaphylos spp. were presumably incorrectly added by Sivanesan (1984) and should also be excluded from the list of expected hosts of M. quinqueseptatum because of the occurrence on these host plants of the similar Limacinia moniliformis var. moniliformis (Barr, 1955), currently Metacapnodium moniliforme (L. R. Fraser) S. Hughes (Hughes, 1981).
The distribution of euantennariaceous and metacapnodiaceous sooty moulds in Taiwan has been undocumented to date. This study revealed that Euantennaria/ Euantennaria pleioblasti (Euantennariaceae) and Metacapnodium/Metacapnodium cf. quinqueseptatum (Metacapnodiaceae) occurring in the subalpine zone can be newly added to the mycobiota of Taiwan. In addition to these, the monocotyledonous, bambusoideaeous genus Pleioblastus native to East Asia, primarily Japan and China (Ohrnberger, 1999; Uchimura, 2014), is newly listed as host plants of these sooty moulds. However, more collections are needed to determine whether E. pleioblasti and Metacapnodium cf. quinqueseptatum are endemic to Taiwan as well as determine the range of their host preference or specialization.
The authors declare that they have no conflict of interest.
One of the authors (J.S.) is grateful to Dr. Yoshimichi Doi (Tsukuba, Japan) for providing a single collection of sooty moulds from Taiwan and Dr. Hideaki Ohba at The University Museum, The University of Tokyo for identifying the host plant. J.S. also wishes to thank the late Dr. Stanley (“Stan”) J. Hughes (Ottawa, Canada) for his helpful comments on the preliminary identification of sooty moulds from Taiwan and also for a long-term based loan of the type and authentic specimens of Metacapnodium quinqueseptatum in Herb. DAOM (Ottawa). We also thank two anonymous reviewers for their suggested improvements on the manuscript. The early phase of this research was supported in part by a Grant-in-Aid for Scientific Research No. 58480017 (1983-1984) from the Ministry of Education, Science and Culture (currently Ministry of Education, Science, Culture, Sports and Technology), Japan to J.S.
