The genus Cudonia Fr. was traditionally arranged in the family Geoglossaceae (Durand 1908; Corner 1929, 1930; Mains 1940, 1955; Imai 1941; Maas Geesteranus 1964) or in the Leotiaceae (Korf 1973) based on morphology. Nannfeldt (1942) suggested that Cudonia and Spathularia Pers. share characters with the members of Phacidiaceae (including Rhytisma Fr., now a member of Rhytismataceae, Rhytismatales). The relationship between Cudonia and Spathularia was then confirmed by molecular studies (Gargas et al. 1995; Platt & Spatafora 2000; Gernandt et al. 2001; Lutzoni et al. 2001). Phylogenetic analyses showed that Cudonia, and Spathularia including Spathulariopsis Maas Geest. form a strongly supported monophyletic clade within the Rhytismatales (Pfister & Kimbrough 2001; Wang et al. 2002, 2006, 2007, 2009; Ge et al. 2014).

In contrast with most members of Rhytismatales forming ascomata immersed within the host tissue, the ascomata of Cudonia and Spathularia develop on soil or among mosses and form erect ascomata (Wang et al. 2009). The hymenia are covered by a stromatic membrane at early stages of development (Nannfeldt 1942; Wang et al. 2002). This layer is a developmental character that unites Cudonia, Spathularia, and members of Rhytismataceae, as suggested by Nannfeldt (1942) and Wang et al. (2002). Other Rhytismatales-like features of Cudonia and Spathularia are ascospores with gelatinous sheaths and simple asci lacking an amyloid pore (Wang et al. 2002, 2007).

About ten species in Cudonia, ten species in Spathularia (including Spathulariopsis) have been recognized (Kirk et al. 2008). Several species of the genera were reported from China (Zhuang 1998a, 1998b, 2001, 2005). However, many species are still undescribed (Ge et al. 2014; Zheng et al. 2020).

During the study of macrofungi in southwestern China, the authors uncovered two unusual and undescribed species of Cudonia from the eastern Himalayas and the Hengduan Mountains region, one of the world’s hotspots of biodiversity (Mittermeier et al. 2005; Yang 2005). They are described and illustrated herein.

Macromorphological descriptions are based on field notes, field line drawings and color slides. Color codes of the form “3A4” are from Kornerup & Wanscher (1981). Microscopic studies were based on dried herbarium material. Sections cut with a new razor blade under a stereomicroscope and gently squashed tissues were studied. Measurements, and illustrations of spores were usually made under cotton-blue-lactic-acid using bright field and phase contrast optics of a compound microscope (Zeiss Axioskop 40). For studies of hymenium, stromatic layer and trama of ascoma, sections were mounted in 3% KOH. Melzer’s reagent was used to test the ascus apex iodine reaction. The materials are deposited at the Herbarium of Cryptogams, Kunming Institute of Botany, Chinese Academy of Sciences (KUN-HKAS). Information on DNA sequences generated from the types by Ge et al. (2014) is provided.

Cudonia claviformis Zhu L. Yang, sp. nov. Figs. 1A, 2

Fungal Name: FN 571209

Diagnosis: Cudonia claviformis is somewhat similar to Spathularia flavida var. ramosa Mains. However, the latter taxon has compressed-clavate ascomata, much-branched above paraphyses and often longer ascospores.

Etymology: claviformis, referring to the shape of the ascomata.

Type: China, Xizang (Tibet) Autonomous Region, Jomdo County, Zonglayi Mt., alt. 4 300 m, among mosses under dwarf shrubs of Rhododendron, 4 Aug 2004, Z.L. Yang 4297 (HKAS 45676). DNA sequences from the type: KC833169 (ITS), KC833213 (LSU), KC833298 (rpb2), KC833380 (tef-1α).

Description: Ascomata (Fig. 1A, Fig. 2A) gregarious, clavate, stipitate, 3-6 cm in height.

Ascigerous portion clavate to subcapitate, 5-10 mm in diam., slightly swollen compared with the stipe, yellow to bright yellow [3A4-3A8] when fresh, brownish to brown when dry, smooth, sometimes with shallow depression areas. Stipe 2-4×0.4-0.8 cm, subcylindrical, whitish to greyish to brownish [paler than 6C4], smooth, glabrous, occasionally with minute whitish squamules. Remnants of stromatic membrane not observed.

Hymenium (Fig. 2D) 130-180 µm thick, consisting of paraphyses and asci at different stages of development. Asci (Fig. 2D) 110-160×10-13 µm, clavate to narrowly clavate, attenuated towards the base, thin- to slightly thick-walled (≤0.5 µm), 8-spored; apical portion narrowly round, J-; croziers present. Ascospores (Fig. 2C) 35-53×2-2.5 µm, clavate-filiform to acicular, colorless and hyaline, thin-walled, round at apex, acuminate at base, multiguttulate, non-septate but becoming secondarily septate when forming ascoconidia; wall with a gelatinous layer 1-2 µm thick; gelatinous cap present at apex, and sometimes at both ends. Ascoconidia (Fig. 2B) 2.5-4×2-3 µm, subglobose to obovoid, thin-walled, 1-celled, 1-gutullate, colorless and hyaline, smooth, often nearly filling the asci. Paraphyses (Fig. 2D) filiform, often branched and anastomosing below, strongly curved to circinate or sometimes straight above, lower portion about 1.5 µm in diam., apical portion 2.5-4 µm in diam., colorless and hyaline or with yellowish vacuolar pigment. Interior of stalk and ascigerous portion of textura intricata, loosely interwoven, colorless and hyaline, thin- to slightly thick-walled hyphae (3-8 µm in diam.) becoming more compact and parallel toward surface of stipe (Fig. 2E). Surface of stipe usually glabrous and with longitudinally and compacted arranged, frequently septate, brownish incrusted filamentous hyphae, but in some areas the surface covered with a thin layer of short, frequently septate, more or less irregularly arranged, brownish incrusted filamentous hyphae 4-8 µm in diam. (Fig. 2E).

Habitat and Distribution: Scattered to gregarious, among mosses under dwarf shrubs of Rhododendron, Salix, etc. in subalpine zones of southwestern China.

Remarks: Cudonia claviformis doesn’t pass the traditional concept of Cudonia or Spathularia well (Ge et al. 2014). In the field, it looks like a species of Clavariedelphus Donk (Basidiomycetes), but its microscopical features indicate a species of Cudonia. It is somewhat similar to S. flavida var. ramosa Mains, which was treated as an abnormal form of S. flavida Pers. by Mass Geesteranus (1972). However, the latter taxon, originally described from USA, has compressed-clavate ascomata, much-branched above paraphyses and often longer ascospores (Mains 1955).

A color image of the type of C. claviformis was published under “‘earth-tongue’ apothecia of Cudonia” by Spatafora et al. (2007, Fig. 1I). This species corresponds to “C. sp 10” in Ge et al. (2014), which indicated its phylogenetic independent position.

Cudonia furfuracea Zhu L. Yang, sp. nov. Figs. 1B, 1C, 3, 4

Fungal Name: FN 571210

Diagnosis: Cudonia furfuracea is similar to C. sichuanensis, but differs from the latter by its furfuraceous stipe, narrower ascospores, the loosely arranged elements on the surface of the stipe, and the thicker, brown to brownish remnants of stromatic membrane along the margin of the hymenium or covered the hymenium.

Etymology: furfuracea, referring to the furfuraceous stipe.

Type: China, Xizang (Tibet) Autonomous Region, Jomdo County, Zonglayi Mt., alt. 4 300 m, among mosses under dwarf shrubs of Rhododendron, 4 Aug 2004, Z.L. Yang 4296 (HKAS 45675). DNA sequences from the type: KC833136 (ITS), KC833203 (LSU), KC833296 (rpb2), and KC833369 (tef-1α).

Description: Ascomata (Figs. 1B, 1C, 3A) capitate, stipitate, 3-6 cm in height. Ascigerous portion capitate, subcapitate to subglobose, occasionally slightly compressed, 3-8 mm in diam.; surface of hymenium yellow to bright yellow to pale ocherous [sometimes 4A5-4A7 or 4B8] when fresh, ocherous to brownish or brown when dry, smooth, often covered with remains of a brown to brownish [5E5-5E7] membrane or forming a short limb along the margin of the hymenium. Stipe 2.5-6×0.2-0.4 cm, subcylindrical, whitish to greyish to brownish [paler than 6C3 and 6C4], smooth or apical part with longitudinally striations, covered with whitish to brownish [6B2 and 6B3] furfuraceous squamules.

Hymenium (Figs. 3F, 4) 110-130 µm thick, consisting of paraphyses and asci at different stages of development. Asci (Fig. 3F) 100-120× 10-12 µm, clavate to narrowly clavate, much attenuated towards the base, thin-walled, 8-spored; apical portion narrowly rounded, J-; croziers present. Ascospores (Fig. 3B) 40-55×1.5-2 µm, clavate-filiform to acicular, colorless and hyaline, thin-walled, round at apex, acuminate at base, multiguttulate, non-septate but becoming secondarily septate when forming ascoconidia; wall with a gelatinous layer 1-3 µm thick; gelatinous cap present at apex, and sometimes at both ends. Ascoconidia (Fig. 3C) 2-3×(1.5)2-2.5 µm, subglobose to obovoid, smooth, thin-walled, 1-celled, 1-gutullate, colorless and hyaline, sometimes nearly filling the asci. Paraphyses (Fig. 3F) filiform, often branched and anastomosing below, strongly curved to circinate above, lower portion about 1.5 µm in diam., apical portion 2-3(4) µm in diam., colorless and hyaline or with yellowish vacuolar pigment. Remnants of stromatic membrane on hymenium surface (Figs. 3D, 4) 60-90 µm thick: outermost layer gelatinized, composed of irregularly formed, nearly colorless and hyaline hyphae 3-5 µm wide; medullar layer composed of non-gelatinized, angularly formed, brownish cells (10-15×5-8 µm) with brownish to brown incrustations; innermost layer composed of non-gelatinized, subglobose, colorless and hyaline, occasionally brownish cells (5-10 µm in diam.) in short chains. Interior of sipe and ascigerous portion of textura intricata, loosely interwoven, colorless and hyaline, thin-walled hyphae (3-12 µm in diam.) becoming more compact and parallel toward surface of stipe. Surface of stipe (Fig. 3E) covered with a discontinuous, 40-60 µm thick layer with ellipsoid, ovoid to subglobose cells (7-20×4-8 µm) in short chains and arranged more or less at a right angle to axis of stipe.

Habitat and Distribution: Scattered to gregarious, among mosses under dwarf shrubs of Rhododendron, Salix, etc. in subalpine zones of southwestern China.

Additional material examined. China: Sichuan Province, Seda County, northwest of Seda, along road to Qinghai Province, alt. 3 800 m, among mosses, 9 Aug 2005, Z.W. Ge 829 (HKAS 49324); Xizang (Tibet) Autonomous Region, Jomdo County, Aila Mt., alt. 3 900 m, among mosses under dwarf shrubs of Rhododendron and Salix, 31 Jul 2004, Z.W. Ge 240 (HKAS 46020).

Remarks: Cudonia furfuracea looks very like C. sichuanensis Zheng Wang, originally described from Sichuan Province, southwestern China (Wang et al. 2002). However, A. furfuracea differs from C. sichuanensis by its furfuraceous stipe, narrower ascospores, the loosely arranged elements on the surface of the stipe, and the thicker, brown to brownish remnants of stromatic membrane along the margin of the hymenium or covered the hymenium.

In C. sichuanensis, the stipe is usually glabrous and longitudinally striate to ridged, and the surface of the stipe is completely covered with a stromatic layer (80-100 µm thick) consisting of compacted arranged inflated cells (textura angularis) in short chains at right angel to the axes of the stipe. The remnants of stromatic membrane covered the hymenium, and between the ascigerous head and the stipe of C. sichuanensis are white to whitish, only 40-50 µm thick, consisting of 4-7 layers of inflated cells and an indistinct gelatinized outer layer in the thickness of only 1-2(3) hyphae, without a medullar brown layer (Wang et al. 2002; author’s observations of C. sichuanensis from Shangri-La, Yunnan-HKAS 50402).

Spathularia pilatii Velen., originally described from Turkey, has a globose ascogenous head 1 cm in diam. (Velenovský 1939). It was regarded as abnormal form of S. flavida (Mass Geesteranus 1972). Given that S. pilatii is an independent species, and judging from the very brief protologue (Velenovský 1939), it differs from C. furfuracea by its broader ascigerous portion, shorter stipe, and on rotten wood of conifer.

Cudonia furfuracea corresponds to “Cudonia sp. 12” in Ge et al. (2014), which indicates that C. furfuracea and C. sichuanensis are phylogenetically different from each other.

Cudonia and Spathularia share many important characteristics, such as club-shaped asci with a non-bluing apex in Melzer’s reagent, gelatinously sheathed ascospores, filiform, branched and curved paraphyses, production of conidia on ascospores, and a stromatic membrane that covers the hymenium in the early stages of ascoma development and may disappear or have been destroyed during the ascoma development (Nannfeldt 1942; Mains 1955; Wang et al. 2002, 2007). The differences between the two genera lay only the macro-morphology of the ascomata.

In traditional concept, Cudonia has a pileate ascoma with a sterile underside, while Spathularia usually has a spathulate ascoma with an upper ascogenous portion. Although stunted and degenerate growth forms are occasionally seen in Spathularia, e.g. S. pilatii Velen. (Velenovský 1939) regarded as an abnormal form of S. flavida by Mass Geesteranus (1972), species of clavate or capitate ascomata do occur in the nature: C. claviformis has a clavate ascoma without a distinct compression, while C. furfuracea and C. sichuanensis have capitate ascomata. These taxa are apparently various intermediate forms between the spathulate and pileate ones.

Ge et al. (2014) suggested to merge the two genera Cudonia and Spathularia, but formal nomenclatural treatment was not made. In the present work, the two new species are addressed in Cudonia for the time being.

The author is very grateful to Prof. Bau Tolgor at Jilin Agricultural University and Dr. Zaiwei Ge at Kunming Institute of Botany, Chinese Academy of Sciences for providing valuable collections of Cudonia and Spathularia for study and comparison. He thanks Dr. Jean Evans I. Codjia for providing literature on S. pilatii. The reviewers’ comments and suggestions for the improvement of the manuscript are highly appreciated.