Absidia caatinguensis D.X. Lima & A.L. Santiago, sp. nov.
Index Fungorum number: IF551222; Facesoffungi number: FoF01015; Fig. 1
Etymology: caatinguensis. Referring to biome where the species was first isolated.
Holotype: URM 7156

Colony initially white and becoming brownish gray (MP 15C2), covering the Petri dish (9 cm diam.) for four days and reaching the plate lid (1.5 cm height) in some points in MEA; colony reverse wavy zonate, initially cream to buff (MP12H3) then becoming blackish brown in older cultures due to pigment production in the culture medium. Odour none; rhizoids branched and stolons 5 – 12 μm diam., smoothwalled, hyaline to light gray and irregularly septate. Sporangiophores 40 – 150 (−210) × 2.5 – 5 μm, erect, smooth and hyaline, growing along the stolons and terminally, showing occasionally swellings; solitary to 2 – 6 (−7) in a whorl and these often branched again (up to five times, mostly after 6 days of incubation), often with a septum below the sporangium, rarely showing two septa. Sporangia pyriform (15–) 17.5 – 27.5 μm diam., multi-spored and smooth – walled, apophysate, sometimes with a bell shaped apophysis. Columellae hemispheric, sometimes subglobose, 10 – 20 μm diam., smooth-walled; collar present sometimes. One projection is usually present on upper surface of columellae up to 5.75 μmin length, some are bulbous at distal end up to 2.5 μm in width. Sporangiospores 5 – 7.5 × 2.5 – 3.7 μm, smooth, regular in size and shape, cylindrical, slightly constricted at the central portion. Chlamydospores absent. Zygospores not observed. Probably heterothallic.

Media, temperature tests and mating experiments: On MEA. At 15 °C – slow growth (7 cm in 192 h). At 20 °C – Good growth (9 cm in 96 h) and good sporulation. At 25 °C–Good growth with better sporulation than at 20 °C (9 cm in 96 h). A brown pigment is produced in media.At 31 °C–slower growth than at 25 °C (9 cm in 120 h) and good sporulation. At 35 °C– Lack of growth and sporulation. The growth of A. caatinguensis on PDA was similar to the growth on MEA at 25 °C, but the brown pigment was not produced. At 31 °C– the growth was slower in PDA than in MEA (9 cm in 120 h) with low sporulation. Influence of light: not detected.

Material examined: BRAZIL, Pernambuco, Buíque, Catimbau National Park (8°31′55.8″S, 37°15′34.2″W), Soil. 2013, D.X. Lima. Holotype (URM 7156); living culture deposited at Jena Microbial Resource Collection (University of Jena and Leibniz Institute for Natural Product Research and Infection Biology, Jena, Germany) (JMRC: SF:012107).

Habitat: soil
Notes: Absidia caatinguens is morphologically similar to A. fusca, but differs primarily in its pattern of sporangiophores branching, by the size of sporangiospores and the pigment production in the culture medium (Fig. 164). As A. fusca, some strains of A. caatinguensis produce branched sporangiophores and a brown pigment that begins to appear by 20th day. However, sporangiophores of A. caatinguensis are much more branched than those of A. fusca, and the pigment is produced at temperatures higher than 15 °C d. Absidia caatiguensis sporangiospores are greater than those of A. fusca (3.3 – 4.5 × 1.8 – 3.5) (Hesseltine and Ellis 1964). Additionally, A. fusca colonies show a smooth colony reverse, different from the wavy zonate reverse observed in the new species. Our molecular analyzes (LSU rDNA and 5.8S rDNA) showed that A. caatinguensis is genetically different from the other species of the genus.

Fig. 1 Absidia caatinguensis (holotype) a Colony surface b Four sporangiophores in a whorl c Two sporangiophores in a whorl with occasional swellings d, e Branched sporangiophores f Simple sporangiophore with a bell-shaped apophysis under the sporangium g Simple sporangiophore with columella and a single projection h Sporangiospores.