Purpureocillium atlanticum Araújo, Martins-Cunha, Antonelli & Drechsler-Santos, 2025

Araújo, João P. M., Przelomska, Natalia A. S., Smith, Rhian J., Drechsler-Santos, Elisandro R., Alves-Silva, Genivaldo, Martins-Cunha, Kelmer, Hosoya, Tsuyoshi, Luangsa-ard, Janet J., Perrigo, Allison, Repullés, Mar, Matos-Maraví, Pável, Woods, Roseina, Pérez-Escobar, Oscar A. & Antonelli, Alexandre, 2025, A new species of Purpureocillium (Ophiocordycipitaceae) fungus parasitizing trapdoor spiders in Brazil’s Atlantic Forest and its associated microbiome revealed through in situ “ taxogenomics ”, IMA Fungus 16, pp. e 168534-e 168534 : e168534-

Purpureocillium atlanticum Araújo, Martins-Cunha, Antonelli & Drechsler-Santos sp. nov.

Fig. 1

Diagnosis.

Macro- and micromorphological structures divergent from the type collected by A. Yasuda and characterized by Petch (1939): smaller clava ( 2 cm long versus 6 cm), larger phialides (4–8 × 2.4–4.3 µm versus 4–5 × 2 µm), and larger and cylindrical conidia (3.5–6.6 × 1.6–2.7 µm versus 4–6 × 1.5–2 µm).

Description.

The fungus infects trapdoor spiders buried in the forest floor inside their burrows, covering the spider almost completely with soft, cotton-white mycelium. Stroma single, cylindrical to clavate, slightly sinuous, arising from the host and growing towards the burrow opening, white at the base turning purple and pruinose in the terminal fertile part upon maturity and conidia production; up to 2 cm long × 2–3.5 mm diameter when fresh ( 1.5 cm long × 1–2.5 mm diameter when dried). Conidiophores abundant, densely grouped, hyaline, smooth-walled, with intercalary and / or terminal fertile portion (ca. up to 6 clusters per conidiophore; Fig. 1 F, G ), 140 µm long × 2.6 µm wide, typically enlarging up to 4.5 µm where metulae emerge; metulae (typically up to 5 around a septum, or terminal) and phialides (no more than 10 per metulae) in rosetoid arrangement attached to the septum or terminally on the conidiophore. Metulae typically formed around a septum or terminally (Fig. 1 F, G ), clavate to obovoid, hyaline, (4.5 –) 4.7–7.5 (– 8.7) × (2.44 –) 2.7–4 (– 4.53) µm, borne directly on main hyphae along the conidiophore, with 4–10 phialides. Phialides ellipsoid to obovoid, hyaline, (4.25 –) 5–7.5 (– 8.11) × (2.38 –) 2.67–3.89 (– 4.28) µm, neck absent. Conidia abundant, cylindrical, smooth, and thin walled, hyaline, with characteristic 1–2 droplets inside, (3.49 –) 4.3–6.37 (– 6.6) × (1.6 –) 1.68–2.44 (– 2.7) µm. Sexual morph not observed.

Etymology.

The specific epithet refers to the Atlantic Forest of eastern South America, one of the world’s most biodiverse and threatened biomes.

Holotype.

Rio de Janeiro: Nova Friburgo: RPPN Alto da Figueira ( 22°22'31.0"S, 42°49'44.0"W; c. 1,400 m a. s. l.), 22 Nov 2022, J. P. M. Araújo., A. Perrigo & A. Antonelli ( FLOR 73173 ), on trapdoor spider . FLOR = Herbarium of the Universidade Federal de Santa Catarina, Brazil.

GenBank accession numbers ( holotype FLOR 73173 ): SSU - PX 571242; LSU - PX 571243; TEF - PX 548866.

Notes.

This species is related to P. atypicola , which was described from specimens found on a spider in Japan. The morphological, ecological, geographical, and phylogenetic diversity shown within the P. atypicola clade suggests it is a species complex. The materials examined from the group exhibit a wide range of distinct morphological and ecological features and include specimens from different parts of the world ( Nomuraea atypicola ( Samson 1974; Hywel-Jones and Sivichai 1995); Spicaria atypicola ( Petch 1939)) .

Conservation status and distribution.

Data Deficient (DD). Purpureocillium atlanticum sp. nov. is only known from one site in Brazil’s Atlantic Forest. It is likely that the species also occurs in other similar old-growth and well-preserved sites. Our team has collected sexual stages of “ P. atypicola ” in the Amazon before, but since the clade is now treated as a complex of species, more detailed studies will be conducted on these previously collected P. atypicola - like samples. The cloud forests where it was found are restricted to areas above an elevation of 1,000 m above sea level, and since these areas are highly reduced, fragmented, and dependent on specific microclimatic conditions ( Bruijnzeel et al. 2011; Oliveira et al. 2014), the species might be susceptible to threats caused by climate change and further habitat reduction and fragmentation ( Salazar et al. 2007; Williams et al. 2007; Goldsmith et al. 2013; Gotsch et al. 2014; Pompeu et al. 2014; Helmer et al. 2019).

Figures

Figure 1. Phylogeny of hypocrealean fungi (A), highlighting the Purpureocillium atypicola complex (B) and morphology of the new species, P. atlanticum (C – G). A Maximum likelihood (ML) tree of the order Hypocreales, with P. atlanticum highlighted, obtained from a dataset of the TEF gene. B Purpureocillium atlanticum sp. nov. is indicated by bold font. Details about the country, death location, and host ecology are indicated in the legend at the bottom-left corner. C Trapdoor spider inside its (dissected) burrow covered by white fungal mycelium and the cylindrical purple synnema arising from the cephalothorax. D Close-up of the apical spore-producing region of the fruiting body. F, G Conidiophores forming dense clusters bearing phialides (spore-producing cells) and conidia at the tips.