Lambertella dipterocarpacearum P.N. Singh, S.K. Singh & A.C. Lagashetti, sp. nov.
Index Fungorum number: IF 900321; Mycobank number: MB 900321; Facesoffungi number: FoF 0773601; Figs. 1, 2
Etymology – specific epithet ‘dipterocarpacearum’ refers to the host family.
Holotype – AMH 10226.
Colour code follows – Methuen Handbook of Colour (Kornerup and Wanscher 1978).
On leaf phylloplane of Shorea robusta in terrestrial habitats. Asexual morph: vegetative hyphae smooth walled, branched, septate, anastomoses, sometimes coiled, subhyaline to light olivaceous up to 10.15 µm wide. Stroma none. Chlamydospores absent. Setae and hyphopodia absent. Conidiophores macronematous, mononematous, unbranched to dichotomously densely branched, straight, short, septate, smooth walled, subhyaline to light olivaceous, 4.5–138.90 × 4–6.35 μm, sometimes reduced into conidiogenous cells. Occasionally, a sterile arm is produced near axel of conidiophore. Conidiogenous cells holoblastic, terminal to lateral, determinate, polyblastic, ampulliform, persistent, aseptate, hyaline, 2.88–12.75× 1.61–7.20 μm (x̅=6.30 × 2.70 μm, n=30). Phialides solitary or aggregated, densely produced, ampulliform to lageniform, aseptate, sometimes single to multi- septate, smooth walled, hyaline, 2.59–22.92×1.67–4 μm (x̅=6.31×2.73 μm, n=30). Conidia mostly aggregated in slimy mass heads at the apex of phialides, sometimes produced in chains, globose to subglobose, smooth walled, sub-hyaline to light olivaceous, 1.84–4.22×1.81–2.80 μm (x̅=2.38×2 μm, n=30). Sexual morph: Undetermined.
Culture characteristics – on semi-synthetic agar medium PDA (Potato Dextrose Agar) white (1A1), reaching 6.5 cm diam. in 5 days at 25 °C, with irregular margin, surface filamentous, reverse light yellow (4A4). After aging light yellow (4A3), reverse light yellow (4A3). Hyphae septate, unbranched to branched, sometimes constricted near septa, smooth and thin walled, subhyaline to light olivaceous, 2–10.15 μm wide.
Materials examined – India, Uttar Pradesh, Gorakhpur District, on Shorea robusta (leaf infested with black mold), 5 May 2016, P.N. Singh, AMH10226 (holotype); ex type living culture, NFCCI 4826 (National Fungal Culture Collection of India-WDCM 932).
GenBank Numbers – AMH10226: ITS = MT227126, LSU=MT227018, RPB2=OM313014.
Notes – The present taxon is morphologically distinct from allied species of Lambertella. All the species of Lambertella have been reported to be found in apothecial forms rather producing conidial stage. The sexual stage in the present taxon was not found. Therefore, it was not compared with the allied taxons of the genus Lambertella. The genus Lambertella is morphologically most closely related to anamorphs of Cadophora, Phialocephala, Mollerodiscus and Longia. The present taxon is compared with Cadophora fastigiata (Lagerberg et al. 1927), which is the anamorph of the genus Lambertella. The L. dipterocarpacearum was found in anamorphic state in having subhyaline to light olivaceous globose to subglobose conidia (1.84–4.22×1.81–2.80 μm) produced on tips of phialides in compact dark orangish gleosporic mass. In addition, densely produced phialides, conidiogenous cells, presence of coiled/anastomoses hyphae and sterile arms in axel of conidiophores are the distinct features of this taxon. These features are lacking in Cadophora fastigiata. Flask-shaped, light brown phialides that are produced laterally from hyphae and having funnel-shaped collarette conidiogenous cells in C. fastigiata. Conidia are generally oval to button shaped (3.0–5.5×1.5–2.5 µm). Thus, based on these morphological distinction, L. dipterocarpacearum, is described here as species new to science. Phylogenetic analysis of ITS, LSU and RPB2 sequence data indicates that L. dipterocarpacearum (NFCCI 4826), is a new species in Rutstroemiaceae, which is different from other known species of Lambertella forming a sister clade to Lambertella sensu stricto (Zhao et al. 2016a) with strong ultrafast bootstrap value of 98 (Fig. 3). On megablast analysis, ITS sequence of L. dipterocarpacearum showed 92% (485/525) identity and 13 gaps (2%) with L. corni-maris CBS 184.93 and L. corni-maris CBS 774.95, 92% (483/523) identity and 14 gaps (2%) with L. himalayensis CBS 230.77, 92% (471/512) identity and 14 gaps (2%) with L. pruni CBS 199.47, 92% (472/511) identity and 12 gaps (2%) with L. hicoriae, and 91% (472/519) identity and 12 gaps (2%) with L. pyrolae. To our knowledge, this was isolated for the first time from leaf of Shorea collected from Kusumi Forest, District Gorakhapur, Uttar Pradesh region in India. Moreover, this species is being reported for the first time from India.
Figure 1 – Lambertella dipterocarpacearum (AMH10226, holotype). a Substratum (leaf of Shorea). b Colony morphology on PDA (front view on 5th days). c Stereomicroscopic surface view of colony showing dark orange shiny gleosporic mass of conidial heads. d–g Coiled and anastomosed hyphae. h, i Hyphae bearing developing phialides with conidia. j, k branched conidiophores with sterile arm. l Conidiophore with solitary phialide. Scale bars: d–f=10 μm, g=20 μm, h=20 μm, i=5 μm, j, k=10 μm, l=20 μm
Figure 2 – Lambertella dipterocarpacearum (AMH10226, holotype). a–c Conidiophores with conidial heads. d–i Different types of patterns of conidiophores and arrangement of conidia on phialides. Scale bars: a=10 μm, b, c=20 μm, d–i=10 μm
Figure 3 – Phylogenetic tree of Lambertella dipterocarpacearum (NFCCI 4826) by Maximum-Likelihood method based on combined sequence data of ITS, LSU and RPB2. Rutstroemia firma CBS 115.86 and Rutstroemia firma CBS 341.62 were used as outgroup. The analysis involved 20 nucleotide sequences. Evolutionary analyses were conducted in IQ–TREE multicore version 1.6.11 (Nguyen et al. 2015) by the Maximum–Likelihood method using the best suitable model (TIM2e+G4 model). Ex-type strains are in bold and newly generated sequence is in blue. One–thousand bootstrap replicates were analyzed to get ultrafast bootstrap values, and the values above 50% were represented on nodes in the tree