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A. Taxonomic descriptions

To perform the taxonomic descriptions, a minimum of 50 randomly selected conidia, phialides, conidiophores and chlamydospores were measured to determine their respective size ranges. Colour names and notations used in the descriptions follow Villalobos­Dominguez & Villalobos (1947).

Fusarium incarnatum (Desm.) Sacc. (1886) (See Figs. 1.a.b. Supplementary material)

Common synonym: Fusarium semitectum Berk. & Ravénel (1875)

Macroscopic morphology may vary significantly on different media and incubation conditions; our descriptions are based upon growth on potato sucrose agar (PSA) at 25 °C in darkness. Abundant aerial mycelium, dense, floccose, somewhat powdery in aged cultures, margin entire, sometimes undulating. The color of the mycelium was characteristically white to orange with a brown reverse. The growth rate in PSA was 0.44 cm per day. In synthetic low nutrient agar (SNA) medium a light orange pigmentation was observed due to pionnote clustering. Microscopically hyaline septate hyphae were observed, the conidial system was characterized by elongated phialides (2.20–9.98 × 1.05–1.57 µm, mostly 4.20–1.57 µm), bottle-shaped, resting directly on the hyphae or on branched conidiophores ranging in size between 22–100 × 2–3.5 µm. On this medium microconidia were absent but macroconidia were abundant, with pointed apex and truncated or wedge­shaped base, (–1) 3–5–septate, mostly 3–septate, 11.90–26.66 × 2.60 µm. On oatmeal agar (OM A) medium, the cultures differentiated as brown chlamydospores occurring in chains 5.33–15.99 × 3.99–10.68 µm, mostly 9.32 × 5.33 µm.

In carnation leaf agar (CLA) medium, macroconidia were formed in orange sporodochia and were relatively slender with a curved dorsal surface and straighter ventral surface, 3–5–septate. Fusoid, 3–5–septate mesoconidia formed on mono and polyphialides. Pyriform to obovate, usually 1–septate microconidia were found.

Specimens examined. Argentina, Buenos Aires Province. Chascomús, 35º34´39.86´´ S, 58º 01´ 02.91´´W, 16 m. isolated from eggs of Odontesthes bonariensis, 10-XII-2005. Pacheco Marino. LPSC culture number: 1001.

Fusarium solani (Mart.) Sacc. (See Figs. 1.c.d. Supplementary material)

Common Synonym: Haematonectria haematococca (Berk. & Broome) Samuels & Rossman

Colonies grew rather fast, reaching 0.445 cm diam. in four days at 25 °C on PSA. Aerial mycelium striate, dusty, sparse to dense and floccose, greyish­white, with green to bluish­grey regions and cream reverse.

Conidiophores elongated, verticillate, 26–55 × 1.57–1.05 × 0.52 µm, mostly 31.71 × 1.57 × 0.52 µm. Sporodochia produced in complete darkness, being occasionally blue­green or blue and turning easily to pionnotes. Macroconidia 3–5–septate, mostly 5–septate, 19.90–35.98 × 3.99–5.13 µm, mostly 27.99–3.99 µm, with short, blunt apical cells and indistinctly pedicellate basal cells. Microconidia abundant, 2.66–13.33 × 1.33–3.99 µm, mostly 7.99 × 2.66 µm, arranged in clusters at tip of the monophialide. Chlamydospores were not observed in PSA medium, while in OMA they appeared after 10 days at 25 °C, single or in pairs, with dimensions ranging between 5.33–10.65 × 5.33–10.65 µm, mostly 6.66 µm in diameter.

In CLA medium, macroconidia formed in cream and blue sporodochia and were relatively wide, straight, robust, 4–7 septate. They were oval, ellipsoid, reniform or fusiform, 0–1 septate (occasionally 2) forming round false heads on monophialides.

Specimens examined. Argentina, Buenos Aires Province. Chascomús, 35º34´39.86´´ S, 58º 01´ 02.91´´W, 16 m. Isolated from eggs of Odontesthes bonariensis, 10-XII-2005. Pacheco Marino. LPSC culture number: 1002.

The morphological characteristics of isolate LPSC 1001 agree with the descriptions of Sutton et al. (1998) and Nelson et al. (1983) related to Fusarium semitectum. Our isolate of F. semitectum showed mostly tri-septate macroconidia, which were shorter than those of F. semitectum var. majus and F. incarnatum described by Booth (1971) and Khoa et al. (2004) respectively. The observed phialides were also thinner than those reported by the

above mentioned authors. While the size of microconidia in isolate LPSC 1002 was similar to that of those in F. solani described by Booth (1971), the macroconidia and phialides of the former were shorter. However, the morphology of isolates LPSC 1001 and 1002, when cultured on CLA medium, was similar to that of Fusarium semitectum and F. solani described by Leslie and Summerell (2006) respectively.

B. Models of nucleotide substitution

The best-fit model of nucleotide substitution selected by jModelTest using the Akaike Information Criterion (AIC) was the Transition Model with a proportion of invariant sites and gamma-distributed rate heterogeneity (TIM2 + G), for the EF-1( data set. The analysis was implemented with the derived fixed transition frequencies (1.8913 4.0237 1.8913 1.0000 6.8550 1.0000 for rAC, rAG, rAT, rCG, rCT, rGT, respectively) and fixed nucleotide frequencies (0.2423 0.2942 0.2044 0.2592 for A, C, G, T, respectively). In the analysis of CAM data set, the Tamura-Nei model (Tamura and Nei, 1993) with equal nucleotide frequencies and gamma-distributed rate heterogeneity (TNei ef + G) was found to be the best-fit model. In this case, the derived fixed transition frequencies used were 1.0000 4.0540 1.0000 1.0000 9.7238 1.0000 for rAC, rAG, rAT, rCG, rCT, rGT, respectively. These parameters were used in Neighbor-joining analysis.

Of the three main types of substitution models implemented in MrBayes 3.2, we used the General Time Reversible (GTR) (Felsenstein 2004) for the EF-1( data set, and the Symmetrical model (SYM) (Zharkikh 2004) for the CAM dataset. The corresponding parameters values are listed below:

Maximum likelihod estimation.

EF-1α data set

BIONJ tree topology

Model = GTR+G

partition = 012345

-lnL = 7138.6146

K = 142

freqA = 0.2423

freqC = 0.2999

freqG = 0.2046

freqT = 0.2533

R(a) [AC] = 1.5835

R(b) [AG] = 3.9358

R(c) [AT] = 2.1732

R(d) [CG] = 0.9612

R(e) [CT] = 6.7277

R(f) [GT] = 1.0000

gamma shape = 0.3890

CAM data set

BIONJ tree topology

Model = SYM+G

partition = 012345

-lnL = 4340.3179

K = 81

R(a) [AC] = 0.8712

R(b) [AG] = 3.6969

R(c) [AT] = 0.8298

R(d) [CG] = 0.9492

R(e) [CT] = 8.8634

R(f) [GT] = 1.0000

gamma shape = 0.4340

Felsenstein J. Inferring Phylogenies. Sunderland, (MA): Sinauer Associates, 2004.

Tamura K, Nei M. Estimation of the number of nucleotide substitutions in the control region of mitochondrial DNA in humans and chimpanzees. Mol Biol Evol. 1993 10(3):512-26.

Villalobos-Domínguez CV, Villalobos J. Colour Atlas, 1st edn. Ateneo, Buenos Aires, 1947.

Zharkikh A. Estimation of evolutionary distances between nucleotide sequences. J Mol Evol.1994; 39:315-29.

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