Neodeightonia chamaeropicola D.S. Pereira & A.J.L. Phillips, 2023

Pereira, Diana S. & Phillips, Alan J. L., 2023, Botryosphaeriaceae on palms-a new species of Neodeightonia, N. chamaeropicola, and new records from diseased foliage of ornamental palms in Portugal, Phytotaxa 627 (1), pp. 1921-1935 : 1921-1935

Neodeightonia chamaeropicola D.S. Pereira & A.J.L. Phillips sp. nov., MycoBank MB847703

( Figure 10 )

Etymology: Named after the host genus from which it was isolated, Chamaerops humilis .

Type: PORTUGAL, Lisbon, Parque das Nações, on foliar lesions of Chamaerops humilis ( Arecaceae ), 8 May 2021, Diana S. Pereira (specimen HDP 089 , holotype AVE-F-16, culture ex-type CDP 1446 = CBS KNAW culture collection, ITS sequence OQ 996231, tef1 sequence OR 233669).

Associated with foliar lesions. Sexual morph: Undetermined. Asexual morph: Conidiomata on palm leaf pieces in culture pycnidial, globose to subglobose, slightly papillate, non-stromatic, uniloculate, dark brown to black, solitary, occasionally aggregated, scattered, semi-immersed to superficial or immersed in the host becoming erumpent when mature, glabrous, exuding a creamy, whitish mucoid mass or cirrus of conidia. Conidiophores reduced to conidiogenous cells. Conidiogenous cells lining the pycnidial cavity, hyaline, smooth- and thin-walled, simple, indeterminate, cylindrical, often swollen at the base, ampulliform, straight or curved, aseptate, occasionally 1-septate, enteroblastic, proliferating at the same level giving rise to periclinal thickenings, or proliferating percurrently to form 1–3 annellations, occasionally enteroblastic proliferating percurrently after the formation of a new conidiogenous cell by apical wallbuilding, variable in size, 8.28–24.23 × 3.38–8.55 μm, 95 % confidence limits = 13.80–15.81 × 4.65–5.19 μm (mean ± SD = 14.80 ± 3.63 × 4.92 ± 0.98 μm, n = 50). Conidia broadly ellipsoid to obovoid, apex and base broadly rounded, widest in the middle, thick-walled, initially hyaline and aseptate, becoming pale to dark brown and 1-septate, with melanin deposits on the inner surface of the wall arranged longitudinally giving a striate appearance to the conidia, mostly eguttulate, 6.80–12.42 × 2.71–4.60 μm, 95 % confidence limits = 7.82–8.32 × 3.60–3.81 μm (mean ± SD = 8.07 ± 0.91 × 3.70 ± 0.38 μm), mean ± SD conidium length/width ratio = 2.20 ± 0.29 (n = 50).

Culture characteristics: Colonies on 1/2 PDA, reaching 80 mm diam. after 7 at 20 ℃ in darkness. Surface raised, cottony, with abundant aerial mycelium, with entire, filamentous margin, circular shape, whitish, becoming pale to light brown towards the centre, opaque. Reverse pale, becoming brownish towards the centre. No diffusible pigment.

Additional material examined: PORTUGAL, Lisbon, Parque das Nações, on foliar lesions of Chamaerops humilis ( Arecaceae ), 8 May 2021, Diana S. Pereira (specimen HDP 089), living culture CDP 1447 (ITS sequence OQ996232, tef1 sequence OR233670); Parque das Nações, on foliar lesions of C. humilis ( Arecaceae ), 8 May 2021, Diana S. Pereira (specimen HDP 090), living culture CDP 1512 (ITS sequence OQ996233, tef1 sequence OR233671); Parque das Nações, on foliar lesions of C. humilis ( Arecaceae ), 8 May 2021, Diana S. Pereira (specimen HDP 091), living culture CDP 1566 (ITS sequence OQ996236, tef1 sequence OR233673).

Hosts: Chamaerops humilis (present study), Phoenix dactylifera ( Al-Sadi et al. 2012) , Syagrus romanzoffiana ( da Silva Fonseca et al. 2020) ( Arecaceae ).

Distribution: Brazil (Pato Branco, Paraná) ( da Silva Fonseca et al. 2020), Oman ( Al-Sadi et al. 2012), Portugal (Lisbon) (present study).

Notes: Based on ITS and tef1 sequence data, Neodeightonia chamaeropicola (CDP 1446) is most closely related to N. phoenicum (CBS 122528) ( Figure 4 ) and can be distinguished from it based on 10 fixed unique single nucleotide polymorphisms (SNP) and seven fixed deletion/insertion polymorphisms (DIP) in the partial sequences of those two gene regions (three in ITS and seven in tef1). Thus, N. chamaeropicola and N. phoenicum differ in seven and 10 nucleotide positions in ITS and tef1 partial loci, respectively. Moreover, two additional SNP are observed in the tef1 sequence data between the ex-type strain of N. chamaeropicola and N. phoenicum , although they were not considered fixed, since they are not observed in the remaining N. chamaeropicola strains studied. In short, the ex-type strains of N. chamaeropicola (CDP 1446) and N. phoenicum (CBS 122528) display 98.62 % (501/508, including 4 gaps) and 95.77 % (272/284, including 3 gaps) sequence similarity in ITS and tef1, respectively. Morphologically, N. chamaeropicola (CDP 1446) and N. phoenicum (CBS 122528) are similar, both producing dark brown to black pycnidial conidiomata and ellipsoid, hyaline and aseptate conidia that become pigmented, 1-septate and striate after discharge from the conidiomata ( Phillips et al. 2008) ( Figure 10 , Table 4 ). Nonetheless, they can be distinguished from one another based on conidial morphology ( Phillips et al. 2008) ( Figure 10 , Table 4 ). Conidia of N. chamaeropicola (CDP 1446) (mean = 8.07 × 3.70 μm; L/W = 2.20) are substantially smaller, with a higher L/W ratio than those of N. phoenicum (CBS 122528) (mean = 19.1 × 11.5 μm; L/W = 1.7) ( Phillips et al. 2008). Four strains of N. chamaeropicola were isolated, namely CDP 1446 (ex-type), CDP 1447, CDP 1512 and CDP 1566. They exhibited a minute degree of variation in colony morphology when cultured on 1/2 PDA, which is expressed by the amount of aerial mycelium produced. No relevant variation in micromorphology was observed between these strains. The nucleotide sequence similarity between them was 99.41–100 % for ITS, which result from a single nucleotide position difference in CDP 1566 (i.e. an additional G in ITS1) and three nucleotide positions differences in CDP 1512 (i.e. the insertions of an A and G and a deletion of a G in ITS1), and 99.29 % for tef1, resulting from two nucleotide position differences that were only present in the partial tef1 sequence of the ex-type strain CDP 1446. The isolates of N. chamaeropicola studied were recorded from foliar lesions of Chamaerops humilis , but pathogenicity has not been tested. Neodeightonia chamaeropicola (as “ N. phoenicum ”) has been previously isolated and characterized as a weak pathogen causing root necrosis of Phoenix dactylifera ( Al-Sadi et al. 2012) .

Figures

FIGURE 4. Phylogenetic tree of Neodeightonia generated from BA inference based on combined ITS and tef1 sequences. ML bootstrap support values (ML-BS ≥ 50 %) and Bayesian posterior probabilities (PP ≥ 0.85) are shown at the nodes. Strains with type status are indicated in bold font, the isolates from this study are presented in brown typeface and species are delimited with coloured blocks. The last accepted species names are noted after the strain number in quotation marks where species were synonymised in this study. The scale bar represents the expected number of nucleotide changes per site. The tree was rooted to Botryosphaeria corticis (CBS 119047) and B. dothidea (CBS 115476).

FIGURE 10. Neodeightonia chamaeropicola (CDP 1446, ex-type). A–C. Conidiogenous layer. D–I. Conidiogenous cells. J. Hyaline, aseptate conidia. K, L. Pigmented, 1-septate conidium with longitudinal striations observed through optical sectioning. Scale bars:A = 10 μm, B–L = 5 μm.