Anthracoidea caricis-reznicekii T. Denchev & Denchev, 2016

Denchev, Teodor T. & Denchev, Cvetomir M., 2016, Anthracoidea caricis-reznicekii (Anthracoideaceae), a new species on Carex reznicekii, and A. eburneae, a new record for the USA, Phytotaxa 244 (1), pp. 69-79 : 70-74

Anthracoidea caricis-reznicekii T. Denchev & Denchev , sp. nov. ( Figs 1–15 )

Index Fungorum number: IF551413

Type: —On Carex reznicekii Werier ( Cyperaceae ), USA, Georgia, Clay County, richly wooded ravine slopes, 1 mile E of Fort Gaines, 27 March 1949, coll. R. Thorne, W. C. Muenscher & R. Schumacher 9312, comm. C. T. Rogerson ( NY sine num., holotype).

Diagnosis: — Anthracoidea caricis-reznicekii differs from A. caricis , A. globularis , and A. tomentosae by having mature spores with thicker spore wall, (0.8–)1.0–4.5(–6.0) μm thick, and conspicuous, often numerous (up to 8) protuberances.

Etymology: —Epithet derived from the host plant, Carex reznicekii .

Sori in ovaries, scattered in the inflorescence, as ovoid or broadly ellipsoidal, black, hard bodies, 1.2–1.8 mm long, when young covered by a thin membrane, later becoming exposed; spore mass of the mature sori powdery on the surface. Spores flattened, variable in shape, in plane view slightly irregular to irregularly polygonal, suborbicular, oval, broadly elliptical or elliptical, with conspicuous, often numerous (up to 8) protuberances, in plane view (15–)16– 22.5(–24.5) × 13.5–19.5(–20.5) (19.1 ± 1.8 × 16.6 ± 1.4) μm (n = 200), single spores may reach up to 26 μm in length, in side view 10.5–14 μm thick, middle to dark reddish brown; wall unevenly thickened, (0.8–)1.0–4.5(–6.0) μm thick, thickest at the angles and protuberances, internal swellings 0–3, variable in conspicuousness, light-refractive areas present; minutely to moderately verruculose, warts 0.2–0.5 μm high, spore profile not affected or affected. In SEM warts isolated or confluent forming small groups or short rows. Spore germination unknown.

Known host and distribution: —On Cyperaceae : Carex section Acrocystis : Carex reznicekii , North America ( USA), known only from the type collection ( Fig. 16 ).

Comments: —The spores are at first more regular in shape and have middle reddish brown color and a thinner wall with fewer protuberances than the mature ones.

The host plant (R. Thorne et al., coll. no. 9312) had been initially identified as Carex nigromarginata . In a recently published treatment of the sedges of section Acrocystis in eastern North America, a new species, Carex reznicekii , was described ( Werier 2006). Previously this sedge was recognized as either C. umbellata or C. nigromarginata . Carex reznicekii is distinguished from these species as well as from other members of section Acrocystis by a combination of characters: lack of basal spikes, short culms, narrow leaves, and only slightly red pistillate scales ( Werier 2006). Specimens of Carex reznicekii can easily be separated from that of C. nigromarginata by a complex of characters, among which the most important are (i) narrower leaves, not more than 1.2–2.2(–2.5) mm wide, while the leaves of C. nigromarginata are (1.9–) 2.3–4.5 mm wide, (ii) shorter culms with the longest 1.9–10(–13.7) cm long, while the culms of C. nigromarginata are (4.5–)6.5–38(–51) cm long, and (iii) pistillate scales only tinged with red versus scales with dark purplish coloration which extends laterally from the submargin to the green (less often brown) mid-stripe of the scale for C. nigromarginata ( Werier 2006, Ohio Natural Heritage Program 2008). The specimen examined by us fits well with the protologue description of Carex reznicekii .

Reznicek’s Sedge is endemic to the USA ( Fig. 16 ). It is distributed in the northeastern and southeastern parts of the USA, with a range extending from Rhode Island and southern Ohio to the northernmost part of Florida ( Werier 2006, Ohio Natural Heritage Program 2008, Naczi et al. 2015). It is a quite common species in the Southeast Region ( Werier 2006).

Carex section Acrocystis Dumort. contains about 40 species worldwide, distributed mostly in North America and Eurasia, with a single species known from South America in the Andes Mts ( Egorova 1999, Roalson et al. 2001, Crins & Rettig 2002, Naczi et al. 2015). Twenty-four species occur in North America, some of which have been recently described ( Crins & Rettig 2002, Werier 2006, Sorrie et al. 2011, Zika et al. 2014, Poindexter & Naczi 2014, Naczi et al. 2015). The members of this section predominantly inhabit the dry understory of coniferous and deciduous woodlands ( Roalson et al. 2001, Roalson & Friar 2004). As a result of molecular studies, it was concluded that Carex sec. Acrocystis , as it is currently circumscribed, is polyphyletic ( Roalson et al. 2001, Roalson & Friar 2004, Waterway et al. 2009), but the studied North American species ( C. communis L.H.Bailey ; C. pensylvanica Lam. ; C. rossii Boott ; C. tonsa var. rugosperma (Mack.) Crins , as C. rugosperma Mack. ; and C. turbinata Liebm. , as C. leucodonta Holm ), two Eurasian species ( C. ericetorum Pollich and C. pilulifera L.), and an eastern Asian species ( C. oxyandra (Franch. & Sav.) Kudô ) form a core ‘ Acrocystis clade’, while the species not associated with that clade are of Eurasian origin ( Roalson et al. 2001, Roalson & Friar 2004). The relationship between species in section Acrocystis and other sections is not fully clarified. Potential sister groups of the core Acrocystis clade include members of sections Thuringiaca ( C. flacca subsp. erythrostachys (Hoppe) Holub , C. spissa Hemsl. ), Acrocystis s.l. ( C. grioletii Schkuhr , C. mandshurica Meinsh. , and C. tomentosa L.), Rhomboidales ( C. wahuensis subsp. robusta (Franch. & Sav.) T.Koyama ), and Mitratae ( C. umbrosa subsp. sabynensis (Less. ex Kunth) Kük. ) ( Roalson et al. 2001).

Four Anthracoidea species have been previously described and/or reported on sedges in section Acrocystis : A. caricis (Pers.: Pers.) Bref., A. caryophylleae Kukkonen , A. globularis Kukkonen , and A. tomentosae Vánky.

For a long time, A. caricis (as Cintractia caricis ) had been considered to have a wide host range, including a large number of species of Carex (comp. Zundel 1953). Later, it was recognized as a collective species (including Cintractia irregularis Liro ) which was parasitic on sedges in two sections, Acrocystis and Digitatae ( Kukkonen 1963: 59). Cintractia irregularis was recognized by Boidol & Poelt (1963) as a distinct species and transferred to Anthracoidea . Nannfeldt (1979) reduced the host range of A. caricis to sedges in section Acrocystis .

Vánky (1994: 39, 2011a: 26) suggested that Carex halleriana (section Hallerianae ) must be added to the list of hosts of A. caricis . However, a specimen of Anthracoidea on Carex halleriana ( BULGARIA, Stara Planina Mts, Beledie Han, 21 May 1991, leg. D. Stoyanov, SOMF 20 359) examined by us is rather A. irregularis ( Denchev et al. 2013) . The smut fungus on Carex halleriana deserves further study. Species of Carex section Digitatae , i.e., C. laeta Boott , C. lanceolata Boott , C. pediformis C.A.Mey. , C. rhizina Blytt ex Lindblom subsp. rhizina , and C. rhizina subsp. reventa (V.I.Krecz.) T.V.Egorova (as C. reventa ), were treated as hosts of A. caricis by Guo (2000: 17) but these records need additional examination. It appears that A. caricis does not infect sedges in section Digitatae ( Denchev et al. 2013) .

Based on observations made by Kukkonen (1963: 60), the North American specimens of A. caricis seem to be different from the European specimens by having more regular spores with thinner and evenly thickened walls and weakly developed light-refractive areas.

In the course of our revision of Anthracoidea , many European specimens of A. caricis , including the neotype (on Carex pilulifera , GERMANY, Brandenburg, Kreis Zauch-Belzig, between Beelitz and Schlunkendorf, 10 Jun 1935, E. Fahrendorff, TUR), and two Japanese specimens on Carex oxyandra (Specimens examined:— JAPAN, Hokkaido, Kushiro-shi, Mt. Oakan, 21 Aug 1926, N. Hiratsuka, TSH; JAPAN, Hokkaido, Sapporo-shi, Mt. Saoro-dake, 19 Jul 1926, N. Hiratsuka, TSH; Denchev et al. 2013) were studied. The mature spores of A. caricis-reznicekii differs from those of A. caricis by (i) the presence of conspicuous, often numerous (up to 8) protuberances versus fewer and less conspicuous protuberances of A. caricis , (ii) relatively smaller sizes, (15–)16–22.5(–24.5) (19.1 ± 1.8) μm long vs. 16–25(–27) (21.0 ± 2.0) μm long for the neotype of A. caricis and 17.5–25(–26) (21.8 ± 1.8) μm long for A. caricis on Carex oxyandra , and (iii) a higher maximum value of the wall thickness (up to 6 μm thick).

Anthracoidea caricis-reznicekii differs from A. globularis (Specimen examined:—On Carex globularis L., RUSSIA, Sakhalin Island, 24 Jul 1906, K. Miyabe & T. Miyagi, SAPA; Denchev et al. 2013) by having mature spores with (i) conspicuous, often numerous (up to 8) protuberances, while the spores of A. globularis possess much fewer and less conspicuous protuberances, (ii) a higher maximum value of the wall thickness (up to 6 μm thick versus 3.5 μm thick for A. globularis ), and (iii) higher warts (0.2–0.5 μm high versus up to 0.2 μm for A. globularis ).

Anthracoidea caricis-reznicekii is distinguished from A. tomentosae (Specimen examined:—On Carex tomentosa , BULGARIA, Skalsko, Gabrovo District, 2 Aug 1985, C.M. Denchev, SOMF 18 495; Denchev & Minter 2011d) by having (i) mature spores with conspicuous, often numerous (up to 8) protuberances, while the spores of A. tomentosae possess much fewer and less conspicuous protuberances, (ii) smaller spores, (15–)16–22.5(–24.5) μm long vs. 18–26(– 28) μm long for A. tomentosae , and (iii) a higher maximum value of the wall thickness (up to 6 μm thick vs. 4 μm thick for A. tomentosae ).

Anthracoidea caryophylleae is another species that has been reported on sedges in section Acrocystis . Carex ericetorum was listed as a host of A. caryophylleae by Kukkonen (1963) and Nannfeldt (1979), while C. vanheurckii was given as a host of this smut fungus by Govorova (1990) and Azbukina et al. (1995), from Kamchatka and North Kuriles. According to Popov (1970: 88) and Egorova (1999: 683), C. vanheurckii is a rather closely related species to C. pensylvanica Lam. , the former from East Asia and the latter from North America. Denchev et al. (2013) suggested that infections reported on C. ericetorum and C. vanheurckii should be assigned to A. caricis , based on the close relationship of these species ( Roalson et al. 2001).

The four species may be distinguished by the following key:

Figures

FIGURE 16. Range of Carex reznicekii (after Werier 2006, Ohio Natural Heritage Program 2008, Naczi et al. 2015; yellow solid line) and type locality of Anthracoidea caricis-reznicekii (red dot).

FIGURES 1–2. Anthracoidea caricis-reznicekii on Carex reznicekii (holotype). Habit. Scale bars = 0.5 сm.

FIGURES 3–15. Anthracoidea caricis-reznicekii on Carex reznicekii (holotype). 3–11. Spores in LM. Arrows in Figs 6 and 10 indicate protuberances, black arrowheads in Fig. 8 indicate light-refractive areas, and white arrowhead in Fig. 8 shows an internal swelling. 12–15. Spores in SEM. Scale bars: 3–11 = 10 μm, 12–15 = 5 μm.