Phallus denigricans T.S.Cabral, B.D.B.Silva & Baseia

Cabral, Tiara S., Silva, Bianca DB., Martin, Maria P., Clement, Charles R., Hosaka, Kentaro & Baseia, Iuri G., 2019, Behind the veil - exploring the diversity in Phallus indusiatus s. l. (Phallomycetidae, Basidiomycota), MycoKeys 58, pp. 103-127 : 109-111

Phallus denigricans T.S.Cabral, B.D.B.Silva & Baseia sp. nov. Figure 4

Diagnosis.

This species is characterised by the campanulate receptacle slightly constricted at the base, pale yellow, reticulated, with a prominent apical pore, epigeous development of basidiome, volva varying from white to dark brown and spores up to 4.6 × 2.5 µm.

Holotype.

BRAZIL. Amazonas: São Gabriel da Cachoeira, Itacoatiara Mirim Community (0.304167S, 66.8403W), 1 April 2013, Komura DL (INPA-Fungos 272383). GenBank accessions: MG678486 (ITS), MG678455 (nuc-LSU), MG678541 (atp 6).

Immature basidiomes not observed. Fresh expanded basidiome 98 mm high. Receptacle [25] 26 × 19 [25] mm, campanulate, but slightly constricted at the base, with a prominent apical pore, deeply reticulated surface. Pseudostipe [81] 54 × 10 [22] mm, cylindrical, spongy, white (N00A00M00); pseudoparenchymatous, composed of globose to elongate-ovoid cells, [20.5] 18.5-65.5 [60.8] × [17.5] 19-52.5 [51.2] µm, hyaline. Indusium poorly developed, extending to 2/3 of pseudostipe, white (N00A00M00), 53 mm in length, attached to the apex of the pseudostipe, polygonal to irregular meshes up to 13 × 8 mm. Volva epigeous, white (N00A00M00) in some specimens to dark brown (N60A60M50) in others, with smooth surface or sometimes with small hyphae projections on surface; formed by filamentous hyphae, septate, branched, hyaline, clamp connections present, [2.5] 1.8-5 [3.5] μm diameter, with inflated ends up to 15.5 μm diameter. Rhizomorphs composed of at least two types of hyphae: filamentous thin-walled hyphae, with clamp connections; and thicker hyphae (7-16 µm) that seem to communicate with each other by pores on the inflated tips. Crystals in globose cells were found distributed amongst the hyphae of volva and rhizomorphs of some of the white volva species, measuring 8.2-11.5 × 6.8-10.6 μm. Gleba olive brown (N99A50M10), mucilaginous. Basidiospores elongated, smooth, 3.6-4.6 × 2.2-2.5 µm, hyaline in 5% KOH.

Habitat and distribution.

On soil, in a fragment of upland old-growth forest. So far restricted to the Brazilian Atlantic and Amazon forests, found in the municipalities of Barcelos, Parintins, São Gabriel da Cachoeira and Maraã (State of Amazonas, Brazil); and Natal (State of Rio Grande do Norte).

Etymology.

with reference to the volva becoming blackish.

Other specimens examined (paratypes).

Brazil. Amazonas: Maraã, Reserva de Desenvolvimento Sustentável do Amanã, Ubim Community (2.50500S, 64.66039W), 15 February 2014, Cabral TS (UFRN-Fungos 2805). Barcelos, Bacabal Community (0.49004S, 62.93089W), 7 April 2015, Cabral TS (INPA-Fungos 277791). Parintins, Açaí Community (2.62665S, 56.54041W), 5 March 2015, Cabral TS (INPA-Fungos 272375); 6 March 2015 (INPA-Fungos 272378); Barcelos, Bacabal Community (0.49004S, 62.93089W), 7 April 2015, Cabral TS (INPA-Fungos 272381, INPA-Fungos 272382). Rio Grande do Norte: Natal (6.305093S, 35.361112W), 10 September 2005, Barbosa MMB (UFRN-Fungos 417).

Notes.

Phallus flavidus Kreisel & Hauskn. could be comparable with P. denigricans by the conical receptacle and the indusium size; however, P. flavidus has smaller spores (up to 3.6 × 1.8 µm), the surface of the volva is light grey with an orange flush and the indusium is cream to yellow ( Kreisel and Hausknecht 2009). Phallus impudicus var. obliteratus ( Malençon) Kreisel has a reticulate white receptacle and a rudimentary white indusium; Phallus denigricans also has a poorly-developed indusium, but it is very different from P. impudicus var. obliteratus , where the indusium is hidden under the receptacle ( Calonge 2005, Kreisel and Hausknecht 2009). Phallus callichrous ( Möller) Lloyd is a species described from Brazil, with white indusium and differs from P. denigricans by having an orange to pink receptacle and reddish-violet rhizomorphs. Recently, another indusiate species was described for Brazil, Phallus aureolatus , but it differs from P. denigricans mainly by the strongly developed pore and the merulioid surface of the receptacle ( Trierveiler-Pereira et al. 2017), in addition to its different phylogenetic placement ( Figures 2 , 3 ). Phallus echinovolvatus (M. Zang, D.R. Zheng & Z.X. Hu) Kreisel is another white-indusiate species, characterised mainly by the volva covered with echinulate hyphae projections; in P. denigricans , hyphae projections on the volva surface can also be found in some specimens, but they are smaller than in P. echinovolvatus ( Zang et al. 1988). In P. indusiatus , the receptacle is campanulate, the immature basidiome is hypogeous, so that the volva is buried under the ground when the basidiome is fully developed, the indusium is completely developed reaching the ground and the volva and rhizomorphs have pinkish pigments ( Ventenat 1798). On the other hand, in P. denigricans the campanulate receptacle is constricted at the base, the basidiome has a completely epigeous development, the indusium is poorly-developed reaching only 2/3 of the basidiome and the rhizomorphs and volva are white to brownish.

It is not rare to find Phallus specimens with a blackish volva; recently, a new species was described, P. fuscoechinovolvatus ( Song et al. 2018), but it is quite different from P. denigricans mainly by the strongly echinulated volva. Phallus merulinus (Berk.) Cooke and P. atrovolvatus Kreisel & Calonge are very similar, differing by the volva colour - that is black in P. atrovolvatus and white in P. merulinus - and the habitat ( Calonge 2005). In our ITS phylogenetic analyses ( Figure 3 ), specimens identified as P. atrovolvatus and P. merulinus grouped together in the same clade, indicating a possible identity between these two species. However, no type material was analysed here, which prevents a reliable determination of the species boundaries between P. atrovolvatus and P. merulinus . Similarly, in P. denigricans , we found specimens with white and pale white to brownish volva all grouping in the same clade in phylogenetic trees ( Figures 2 , 3 ). This suggests that the volva colour might change due to the soil properties or with the maturity of the basidiome. Therefore, this specific characteristic - pale or darker volva - should be carefully analysed before it can be used as a diagnostic character in Phallus species.

In both the Bayesian and Maximum Parsimony phylogenetic trees ( Figures 2 , 3 and Suppl. material 2: Figures S1, S2, specimens of P. denigricans grouped in a clade with high support values (ITS tree: pp = 1, bs = 100%), in concordance with morphological data.

Figures

Figure 2. Phylogenetic tree obtained by Bayesian analysis with ITS. Brazilian clades corresponding to the new species and P. indusiatus are indicated (the holotype of each species is in bold). Posterior probabilities and bootstrap values are on the nodes (pp / bs), values of pp <0.95 and bs <90 are not shown. The black dots indicate specimens under Phallus indusiatus deposited in GenBank and downloaded for this study.

Figure 3. Phylogenetic tree obtained by Bayesian analysis with concatenated data (ITS, nuc-LSU and atp 6). Brazilian clades corresponding to the new species and P. indusiatus are indicated (the holotype of each species is in bold). Posterior probabilities and bootstrap values are on the nodes (pp / bs), values of pp <0.95 and bs <90 are not shown (except for P. denigricans clade).

Figure 4. Phallus denigricans UFRN-Fungos 2805, holotype. A Basidiome B blackish and smooth volva in detail C white volva with projections D receptacle with a prominent pore E spores F pseudoparenchymatous hyphae of pseudostipe G hyphae from rhizomorphs H hyphae from volva. Scale bars: 20 mm (A-D), 20 µm (E), 40 µm (F-H).