Calonectria exiguispora N.Q. Pham, Marinc. & M.J. Wingf., 2022

Pham, Nam Q., Marincowitz, Seonju, Chen, ShuaiFei, Rodas, Carlos A. & Wingfield, Michael J., 2022, Soil-borne Calonectria (Hypocreales, Nectriaceae) associated with Eucalyptus plantations in Colombia, MycoKeys 94, pp. 17-35 : 17

publication ID

https://dx.doi.org/10.3897/mycokeys.94.96301

persistent identifier

https://treatment.plazi.org/id/3DCC8EAD-8B6A-50B8-B7E6-8E2ADACBF40A

treatment provided by

MycoKeys by Pensoft

scientific name

Calonectria exiguispora N.Q. Pham, Marinc. & M.J. Wingf.
status

sp. nov.

Calonectria exiguispora N.Q. Pham, Marinc. & M.J. Wingf. sp. nov.

Figs 4 View Figure 4 , 6A, B View Figure 6

Etymology.

“exiguus” (Latin) = small + “spora” (Latin) = spores, referring to the small macroconidia produced by this species.

Diagnosis.

Phylogenetically close to C. piauiensis and C. brassianae but differs in having smaller macroconidia.

Type.

Colombia: Risaralda, Quinchía. Soils in Eucalyptus plantation. August 2016. C.A. Rodas. (Holotype PRU(M) 4501, stored in a metabolically inactive state; ex - holotype CMW 49752 View Materials , CMW-IA 160). GenBank : OP796405 View Materials (ACT) ; OP822275 View Materials (CMDA) ; OP822382 View Materials (HIS3) ; OP822489 View Materials (RPB2) ; OP822168 View Materials (TEF1) ; OP822596 View Materials (TUB2) .

Description.

Sexual morph not observed. Conidiophores scarce on SNA, consisting of conidiogenous apparatus and stipes, branched or simple. Stipes infrequent, elongated, septate, 75-273 µm long, 2-5 µm wide near base, tapering towards apex, simple or occasionally dichotomously branched, mostly being part of conidiogenous apparatus; vesicles terminal, slightly inflate to ellipsoidal, 2-5 µm wide. Conidiogenous apparatus hyaline, simple or branched in 1-3 (-4) tiers, uncommonly developing from stipes; main axis upright, septate, 20-275 × 3-7 µm; branches doliiform to cylindrical, primary branches 8-39 × 3-7 µm, secondary branches 8-24 × 2-6 µm, tertiary branches 10-23 × 2-5 µm, quarternary branches 10-14 × 3-4 µm. Conidiogenous cells holoblastic, hyaline, discrete, cylindrical to tapered above, often constricted near base, with periclinal thickening, 8-20 × 3-5 (11.8 ± 2.71 × 3.2 ± 0.5) µm. Macroconidia hyaline, cylindrical, round at apex, 1-septate, septum sub-median or median, guttulate, 21-40 × 3-4 (30.9 ± 4.09 × 3.5 ± 0.23) µm. Chlamydospores present, scarce, in clumps or in chains. Mega - and microconidia not observed.

Colonies on 2% MEA in the dark for 6 d, white on surface, pale luteous in reverse, with moderate amount of aerial mycelium, with entire edges. Optimal growth temperature at 25 °C reaching 65.2 mm in 6 d, followed by 20 °C (57.3 mm), 15 °C (39.8 mm), 10 °C (19.7 mm), 5 °C (8.2 mm), no growth at 30 °C and 35 °C. Colonies kept at 30 °C and 35 °C being relocated to 25 °C for another 6 d revived (30 °C) and showed no growth (35 °C). Colonies on 2% MEA in the dark for 30 d, white to umber on surface, umber to dark brick in reverse, with flat mycelia.

Distribution.

Colombia.

Material examined.

Colombia: Risaralda, Quinchía. Soils in Eucalyptus sp. plantation. August 2016. C.A. Rodas. (PRU(M) 4502, stored in a metabolically inactive state; culture CMW 49753 View Materials , CMW-IA 161) .

Notes.

Calonectria exiguispora is a member of the C. candelabrum species complex ( Liu et al. 2020). It shares some characteristics with other species in the complex, such as 1-septate macroconidia and 'ellipsoidal to obpyriform’ shape vesicle. However, it can be distinguished from most species in the complex by its smaller conidial dimensions (21-40 × 3-4 µm, avg. 30.9 × 3.5 µm) except for C. brevistipitata (29-35 × 3-4 µm, avg. 31 × 3.5 µm, isolated from Mexican soil) and C. stipitate (27-37 × 3-6, avg. 32 × 4 µm, isolated from Colombian Eucalyptus sp.) ( Lombard et al. 2016). Nevertheless, these two species are distantly related to C. exiguispora (Fig. 3 View Figure 3 ). Recently Liu et al. (2020) reduced C. stipitata to synonymy with C. spathulata , the conidial dimensions of which range from 48-100 × 4-6 µm (avg. 80 × 6 µm). They regarded the smaller conidial dimensions of C. " Calonectria stipitata " as representing intraspecific variation. Calonectria exiguispora is phylogenetically closely related to C. piauiensis and C. brassianae , which were isolated from soils associated with Eucalyptus brassiana trees in Brazil ( Alfenas et al. 2015). These two species, however, have much larger conidial dimensions: C. piauiensis (38-60 × 3-5 µm, avg. 49 × 4.5 µm) and C. brassianae (35-65 × 3-5 µm, avg. 53 × 4 µm) ( Alfenas et al. 2015). It can be differentiated from its most closely related species by sequences of ACT, CMDA, HIS3, RPB2, TEF1 and TUB2 gene regions.