Mucor merdicola C.A. de Souza & A.L. Santiago, sp. nov.
Index Fungorum number: IF 551679, Facesoffungi number: FoF 01327, Fig. 1
Etymology – merdicola. Merda-dung, cola-dwelling.
Holotype – URM 7223

Colony initially white then becoming yellowish to cream (MP 19D1) with yellowish reverse (MP 11 J6), reaching 9.5 cm in diam. and 9 mm in height after 4 days in MEA at 25 °C. Sporangiophores simple or repeatedly sympodially branched, erect, some slightly curved, arising from aerial hyphae (3–) 5 – 15.5 (–18) μm diam., hyaline, smooth walled, with or without yellowish contents. Sporangia globose (16–) 17.5 – 60(–85) μm diam., initially yellow becoming greyish brown with diffluent wall, smooth-walled. Columellae globose (12.5–)15 – 45(–50) μm, subglobose and applanate (15–)20 – 29 × 30 – 34(–35) μm, hyaline or light to grey, smooth-walled; collar absent or little evident. Sporangiospores smooth-walled, hyaline, mostly ellipsoid to fusiform (2.5–)5 – 7 × 5 – 8.5(–10.5), but also ellipsoid 4 – 7.5 × 3 – 7.5(–10) μm or subglobose (2.5–)4 – 7.5(–8.5) μm diam., rarely globose. Rhizoids poorly developed. Chlamydospores globose, subglobose, doliform, some bizarre in shape. Zygosporangia not observed.

Media and temperature tests – On MEA. At 5 °C – lack of growth and sporulation. At 10 °C – slow growth colonies, reaching 5.9 cm in diam. after 168 h; poor sporulation. At 15 °C – Slow growth (9 cm in 192 h); good sporulation. At 20 °C – Better growth than at 10 and 15 °C (9 cm in 120 h); good sporulation. At 25 °C – better growth (9 cm in 72 h); excellent sporulation. Growth reasonably good at 30 °C (9 cm in 144 h); good sporulation. At 35 °C – limited growth (3.3 cm in 168 h); rare sporophores production and poor sporulation. At 40 °C – lack of growth and sporulation. The growth of M. merdicola on PDA was a slightly slower than on MEA at all tested temperatures.

Material examined – BRAZIL, Arcoverde: Instituto Agronômico de Pernambuco (IPA) (8°25′00″S; 37°04′00″ W), in dung samples, Bos taurus L., breed Holandesa. Dung, 05.IX.2014, leg. C.A.F de Souza (URM 7223) and deposited in the Jena Microbial Resource Collection (University of Jena and Leibniz Institute for Natural Product Research and Infection Biology, Jena, Germany) (JMRC:SF:012175).
Habitat – Dung.
Notes – Mucor merdicola is morphologically similar to M. circinelloides f. circinelloides Tiegh. The former is distinguished from M. circinelloides f. circinelloides as it produces globose, subglobose and applanate columellae, differing from the obovoid to ellipsoidal columellae of M. circinelloides f. circinelloides as described by Schipper (1976). The author describes globose columellae in M. circinelloides f. circinelloides only in the small sporangia. Additionally, M. merdicola presents sporangiospores smooth-walled, mostly ellipsoid to fusiform, 5 – 7 × 5 – 8.5 μm, but also ellipsoid, subglobose and rarely globose, whereas M. circinelloides f. circinelloides sporangiospores are only ellipsoidal, mostly 5.4 × 4 μm (Schipper 1976). Our molecular analysis (ITS and LSU) revealed that M. merdicola is genetically different from the other species of the genus and placed the new species within the M. hiemalis group (Figs. 2 and 3), in which species are characterized as producing tall sporangiophores that are weakly sympodially branched, and small sporangia that do not exceed 80 μm diam., while M. merdicola produces sporangiophores that are repeatedly sympodially branched, similar to the ones produced by the species from the M. circinelloides group (Fig. 1b).

Fig. 1 Mucor merdicola (holotype) a Colony surface b A sympodially branched sporangiophore c, d Simple sporangiophores with sporangia e – g Simple sporangiophores with columellae with different shapes h Sporangiospores.

Fig. 2 a Phylogenetic tree of M. amphibiorum group constructed using the ITS rDNA sequences. Mortierella parvispora was used as outgroup. b Phylogenetic tree of M. hiemalis group constructed using the ITS rDNA sequences. Mucor gigasporus was used as outgroup. Sequences are labeled with their database accession numbers. Support values are from Bayesian inference and maximum likelihood analyses (values above and below of the branches, respectively). Sequences with only ITS1 and 5.8 s rDNA are marked with *. New taxa are in blue and ex-type strains in bold.

Fig. 3 Phylogenetic tree of Mucor constructed using the large subunit (LSU) rDNA sequence data. Circinella species were used as outgroup. Sequences are labeled with their database accession numbers. Support values are from Bayesian inference and maximum likelihood analyses (values above and below the branches, respectively). The sequences obtained in this study are annotated in blue.