Lysurus brachistriatus sp. nov. is a beautiful tiny species that morphologically resembles a smaller basidiomata of Lysurus cruciatus (Lepr. & Mont.) Henn. or L. cruciatus var. nanus Calonge & B. Marcos, and like these species, it consists of a pseudostipe and a receptacle formed by free arms at the maturity (Martín et al. 2005; Ribeiro et al. 2022). An important feature present in the new species is the volva formed by 4 sublayers, not previously observed in any species of this genus. Initial analyses of the molecular data using Maximum Likelihood and Bayesian inference, focusing on the ITS, LSU and ATP6 genetic regions, showed that the species is indeed closely related to both Lysurus species previously cited (L. cruciatus and L. cruciatus var. nanus), without a good support that separates them, or who is closest to whom in the phylogeny. However, analyses using the RPB2 region, marker a clear distinct grouping, placing the new Lysurus species separate from L. cruciatus and in a clade with L. borealis (Burt) Henn. (Fig. 3). It is noteworthy that some authors consider L. borealis to be a synonym of L. cruciatus (Melanda et al. 2023), based on the positioning of a single individual sample available in GenBank in the phylogenetic analysis. Therefore, the most appropriate approach is to make a direct comparison of the species’ morphologies using what is described in the literature.
The most detailed morphological descriptions of L. borealis in the literature can be found in the works of Burt (1894) and Wakefield (1918), when specimens of L. borealis were still treated as “plants”. According to Burt's descriptions (1894), the species is characterized by a receptacle with pale red arms, and is often found in rubbish piles, from September to November, in Chiswick, England. In one of his experiments, Burt (1894) cultivated eggs of this species in his own home, without the incidence of sunlight, and when they developed he observed that the mature basidiomata did not have reddish arms, but instead, it had whitish arms. This observation led him to compare L. borealis with L. australiensis Cooke & Massee, the latter typically having whitish arms. Thus, Burt (1894) concluded that the incidence of light on the environment is fundamental in determining the color of the receptacle and in differentiating Lysurus species.
In Wakefield's (1918) work, the author challenges Burt's (1894) ideas by stating that the difference in lighting does not necessarily explain the fact that L. australiensis typically has whitish arms, while species from the northern hemisphere, like L. borealis, typically have reddish arms. According to Wakefield (1918), both species are nearly identical except for this color variation, suggesting that they are probably the varieties L. borealis var. klitzingii Henn. and L. borealis var. serotinus Peck, and thus may belong to the same group of the species L. borealis. Considering Wakefield's hypothesis (1918), which proposed a probable geographic differentiation of these species varieties, as well as the emphasis on the importance of collecting more of these organisms, we can believe that a future in-depth investigations adopting a molecular, phylogeographic and integrative approach is important. This is particularly true given the inconsistency of the color in the morphological characters, which does not guarantee that both species are synonyms, varieties, or completely different species. And due to the lack of ITS rDNA sequences from L. borealis, the gene region commonly used for fungal barcoding, the definition of this taxon can still be considered inconsistent.
In order to determine the phylogenetic position of L. brachistriatus, tests were performed with all the gene regions obtained for the new species here in this work with the markers employed (ITS, LSU, RPB2 and ATP6). None of the alignments (ITS, LSU, RPB2, or ATP6) includes all four species simultaneously (Lysurus brachistriatus sp. nov., L. cruciatus, L. cruciatus var. nanus, and L. borealis) due to data absence, despite the inclusion of all available data from GenBank. Furthermore, the possibility of species differentiation in response to the use of RPB2 (Fig. 3. ITS, LSU and ATP6 tree not shown), a single-copy and conserved gene, cannot be ignored, and this may be a good indication that L. brachistriatus is indeed a distinct species. Větrovský et al. (2016) suggested that results obtained from analyses using RPB2 recover tree topologies with less bias than results obtained with ITS in general analyses involving the phylum Basidiomycota.
Returning to the direct comparison between Lysurus brachistriatus and its closest relatives, L. cruciatus and L. cruciatus var. nanus, the three species differ in the size and color of their major morphological structures, such as the receptacle, pseudostipe, volva, and gleba (Table 3). In Lysurus brachistriatus sp. nov. the size of the mature basidiome is smaller, with a height of 54 mm, compared to the sizes of L. cruciatus (63–85 mm in height) and L. cruciatus var. nanus (59–71 mm in height) (Martín et al. 2005; Cortez et al. 2011).
The structure of the receptacle in the three species is also highly similar, featuring apical arms with a convex internal surface and a concave external surface. However, the newly discovered species of Lysurus from western Bahia exhibits a rough to striated internal surface with grayish-yellow tones and a smooth creamy to whitish external surface. In contrast, Lysurus cruciatus has a pastel red inner surface and a grayish red outer surface. Specimens of L. cruciatus var. nanus exhibit an internal surface with a rough to furrowed appearance and an orange-red color, while the external surface is yellow-orange. Additionally, the length of the apical arms of L. cruciatus var. nanus is considerably shorter (9–12 mm), and L. cruciatus is much larger (21–34 mm). This places Lysurus brachistriatus as a species with intermediate measurements compared to the other two (11–20 mm) (Martín et al. 2005; Cortez et al. 2011).
Another species similar to Lysurus brachistriatus is Lysurus mokusin (L.) Fr and Lysurus periphragmoides (Klotzsch) Dring, as both species have lysuroid basidiomata, hollow pseudostipe, and gleba with a foul odor at maturity. However, L. mokusin can reach a height of up to 130 mm, with a pale pink prismatic pseudostipe, short arms united in a pine tree shape that open slightly at maturity, and an orange internal color with a brownish external color (Calonge and Gonçalves-Silva 2006). These features are not observed in L. brachistriatus. About Lysurus periphragmoides, this species has a receptacle with a globose crown and a reticulated surface, which are not observed in Lysurus brachistriatus (Dring 1980; Calonge and Gonçalves-Silva 2006).
Lysurus brachistriatus and Lysurus habungianus G. Gogoi & Parkash also exhibit similarities in having a hollow and whitish pseudostipe, as well as a gelatinous gleba with a foul odor and olive-green color (Gogoi and Parkash 2015). However, L. habungianus exhibits a receptacle with pointed and spiny structures on the external surface of the arms, measuring between 5–15 mm in length, while Lysurus brachistriatus has a receptacle formed by free and striated arms (Gogoi and Parkash 2015). The discovery of Lysurus brachistriatus represents the first record of this species for science and for the Brazilian Cerrado biome.
Table 3
Taxonomic comparison of Lysurus brachistriatus sp. nov. with morphologically closely related species. Descriptive details of the other species are taken from Martín et al. 2005 and Cortez et al. 2011.
| | Lysurus brachistriatus sp. nov. | L. cruciatus | L. cruciatus var. nanus |
| Expanded Basidiome | 54 mm in height, measured from the basal volva to the fertile portion of the receptacle | 63–85 mm in height, measured from the basal volva to the fertile portion of the receptacle | 59–71 mm in height, measured from the basal volva to the fertile portion of the receptacle |
| Receptacle | 6 apical arms, 11–20 mm long, free at maturity, inner surface convex, rough to striated, grayish yellow in color: outer surface concave and smooth, cream to whitish in color | 4–7 apical arms, with 21–34 mm long, free at maturity, inner surface convex, rough to striated, pastel red in color; outer surface concave and smooth, reddish gray in color | 5–6 apical arms, with 9–12 mm long, free at maturity, inner surface convex, rough to striated, orange-red in color; outer surface slightly concave and smooth, yellow-orange in color |
| Pseudostipe | 16 mm in height × 27 mm in diameter, subcylindrical to slightly conical, white; hollow at the base; spongy surface and composed of hyaline pseudoparenchymatous cells, globose, subglobose to irregular, measuring 17.9–46.7 × 12.0– 35.4 µm. | 60–100 mm in height × 10–25 mm in diameter, cylindrical, white to cream; hollow at the base; spongy surface and composed of hyaline pseudoparenchymatous cells, globose to subglobose, measuring 19.2–30.5 × 17–31.6 µm. | 44–58 mm in height × 7–9 mm in diameter, subcylindrical to slightly conical, white; hollow at the base; spongy surface |
| Volva | Present at the base of the pseudostipe, saccate, formed by a clear and viscous gelatin, grayish orange to pale orange in color, almost pinkish, composed of four remaining sublayers present at the base of the peridium | Present at the base of the pseudostipe, saccate and thick, formed by a clear and viscous gelatin, whitish in color, with a translucent and thick inner layer and a whitish outer layer, thin and with membranous consistency | Present at the base of the pseudostipe, 14–21 × 13 mm, saccate, formed by a clear and viscous gelatin, whitish in color, covered by sand; and with a rhizomorph |
| Gleba | Slimy, olive-brown at maturity and with a foul odor | Deliquescent, grayish-brown at maturity and with a foul odor | Slimy, dark brown at maturity and with a foul odor |
| Habitat | Growing on ruminant manure, among grass | Growing in soil, on forest edges | Growing in sand or sandy soil, among grass |
| Basidiospores | Cylindrical, 3.2–4.2 × 1.5–1.8 µm, thin-walled, smooth and hyaline | Ellipsoid to oblong, 4.0–4.5 × 1.5–2.0 µm, thin-walled, smooth and hyaline | Ellipsoid, 3.5–4.5 × 1.5–2.0 µm, thin-walled, smooth and hyaline |
Taxonomictreatment
Lysurus brachistriatus Dourado-Barbosa, R.L. Oliveira & R. Cruz sp. nov.–Holotype: BRAZIL. Bahia, Barreiras: Barbosa Family Farm, on herbivore dung, among grass, 12°7’11.25” S, 45°4’26.43” W, 3 Jan 2022, K. D. Barbosa (holotype BRBA–Fungos 0139) [MycoBank # MB853192] (Figs. 2 and 4).
Etymology
Based on the striations formed on the fertile portion of the receptacle's arm.
Diagnosis: Lysurus brachistriatus is characterized by a small basidiome when compared to the closest species Lysurus cruciatus and L. cruciatus var. nanus; receptacles that become free at maturity with a convex, rough to striate inner surface, grayish yellow in color, and a concave and smooth outer surface, creamy to whitish in color. Additionally, it also has a subcylindrical to slightly conical pseudostipe and a grayish-orange volva that becomes pale orange, almost pinkish at maturity, and is composed of four layers that remain at the base of the peridium.
Description: Immature basidiomata 19 mm in diameter, globose to ovoid, white to yellowish-white in color (4A1–4A2), with a small rhizomorph 4 mm long, white (4A1), buried beneath a layer of dung. Mature basidiomata 52 mm tall. Receptacle formed by a pseudostipe covered by a basal volva, and a pileus formed by six (6) arms with viscous gleba. Pileus (fertile portion of receptacle) measuring 20–11 mm in length, with 6 arms free at maturity, inner surface convex, rough to striate, grayish yellow (4B4). Outer surface concave, smooth, white (4A1). Gleba slimy, olive brown (4F3) at maturity, with foul odor. Pseudostipe 27 mm × 16 mm in diameter, cylindrical to slightly subcylindrical, white (4A1), hollow inside and with a spongy consistency. Volva present at the base of the pseudostipe, saccate, formed by a clear and viscous gelatin, grayish orange to pale orange in color, almost pinkish, composed of four remaining sublayers arranged in two layers, present at the base of the basidiome. These layers are characterized as follows, from the outermost to the innermost portion: an Outer layer formed by two sublayers, the outer one being gelatinous (Outer layer 1), and the inner one being fibrous (Outer layer 2); and an inner layer also formed by two sublayers, arranged in the same pattern, with the outer one being gelatinous (Inner layer 1), and the inner one being fibrous (Inner layer 2). Rhizomorph not observed (Fig. 4).
Basidiospores cylindrical, 3.2–4.2 × 1.5–1.8 µm (3.6 ± 0.2 × 1.7 ± 0.1 µm; Qm = 2.13; n = 30 spores), wall ≤ 0.6 µm, smooth, hyaline. Pseudostipe exhibiting globose, subglobose and irregular cells, 17.9–46.7 × 12.0–35.4 µm, wall ≤ 1.5 µm diam, hyaline. Microscopically, the 4 sublayers of the volva from the outermost to the innermost, have the following characteristics: Outer layer 1 (gelatinous outer layer) composed of filamentous hyphae, 2.0–4.6 µm in diameter, wall ≤ 0.7 µm diam., thin, not septate, with small number of branchs, without clamp connections, without crystals, hyaline; Outer layer 2 (fibrous outer layer) composed of filamentous hyphae, 1.9–5.5 µm in diameter, wall ≤ 0.9 µm in diameter, thin, rarely septated (almost asseptated), unbranched, without clamp connection, without crystals, hyaline; Inner layer 1 (gelatinous inner layer) composed of filamentous hyphae 1.6–3.5 µm in diameter, wall ≤ 0.8 µm in diameter, thin, not septate, unbranched, without clamp connections, with crystals, hyaline. Inner layer 2 (fibrous inner layer) composed of filamentous hyphae with inflated 2.0–4.6 µm in diameter, wall ≤ 0.7 µm in diameter, thin, septate, unbranched, without clamp connections, without crystals, hyaline (Fig. 5).