III. Species with Pigmented and Thickened Perithecial Walls
In this section conidia are catenulated from phialides united on sporodochia or pionnotes, or from short lateral branches of aerial, pigmented hyphae. Conidiophores are rarely produced singly, but if so, then they are more or less verticillately branched. When united on pionnotes or sporodochia, conidiophores are obscurely differentiated from the pseudoparenchymatous stroma. Conidia are either unicellular, or bear one or more transverse septa. Life histories of species are described under the following subsections:
1. Species with conidia typical of the form genus Tubercularia.
2. Species with conidia typical of the form genus Cylindrocarpon.
3. Species with conidia typical of the form genus Fusarium.
1. Species with Conidia Typical of the Form Genus Tubercularia
Unicellular conidia are catenulated from phialides arising as terminal branches of short conidiophores arranged superficially on pseudoparenchymatous sporodochia. N. cinnabarina (Tode) Fr. is the only species present in New Zealand.
Nectria cinnabarina (Tode) Fr.
Sporodochia are erumpent, to 3 mm diameter, orange sometimes amber, translucent, pseudoparenchymatous with cells 5–10μ diameter, pigmented and thickened. Conidiophores are 50–100μ long, compacted together. Conidia are one-celled, oblong or oval, sometimes cylindrical or allantoid, 6.8 × 2–2.5μ, hyaline. Cultures have not been studied. The conidial stage is named Tubercularia. vulgaris Tode ex Fr.
2. Species with Conidia Belonging to the Form Genus Cylindrocarpon
Under this subsection are treated N. coprosma Dingley, N. fragilis Dingley, N. galligena Bres. ex Strasser, N. pinea Dingley, N. punicea (K. & Schm.) Fr., N. tasmanica Berk., N. tawa Dingley and N. westlandica Dingley.
The imperfect form-genera Cylindrocarpon and Fusarium are separated from Tubercularia because conidia are provided with one or more transverse septa, although unicellular spores are also present. Wollenweber (1913) erected Cylindrocarpon to contain species with cylindrical, multiseptate conidia, but without chlamydospores. He emended Ramularia (Unger) Fr. to embrace species with cylindrical multiseptate conidia but with chlamydospores.
Later (in 1926) and (in 1928) he placed species with chlamydospores in Cylindrocarpon and appears to have limited Ramularia to species in which conidia were developed in acropetal chains. Consequently, Hughes (1949) held Ramularia to be limited to species in which conidia are developed in acropetal chains of dry terminal thallospores and included in Cylindrocarpon the species with slimy conidia produced in basipetal succession from ends of phialides. Cylindrocarpon is separated from Fusarium by the shape of the macroconidia. In the latter they are falcate with
a distinct apiculate terminal cell and a basal foot cell; in the former cylindrical with rounded apex and without a foot cell.
Nectria coprosma Dingley.
Field collections yielded no conidial forms. Cultures are bay coloured and floccose. Sparsely branched conidiophores form small translucent pionnotes 0.5–1 mm diameter. Conidia are catenulated from terminal phialides, cylindrical, 1–3 septate, rarely 0–2–4 septate (1 septate 14–30 × 3.5–4.5μ, 3 septate 28–47 × 4.5–5μ). Unicellular microconidia are also present, 3–7 × 1.5–3μ. Chlamydospores are absent (Text-fig. 3, 1). Perithecia developed in cultures two months old.
Nectria fragilis Dingley.
Conidia are formed on poorly developed translucent sporodochia formed in longitudinal crevices in bark of the host. In cultures, mycelium is floccose, chestnut brown, sometimes ochraceous. Conidia are formed on translucent pulvinate sporodochia, 1–2 mm diameter. Conidiophores are more or less dichotomously branched and conidia are catenulated from terminal phialides. They are cylindrical, slightly swollen at the base, rounded at the apex, 0–7 septate, mostly 5–7 septate, then 68–81 × 5–6μ. In young cultures two to three weeks old, conidia are 2–3 septate, then 37–56 × 4.5–5μ Microconidia 7.5–10 × 2–3μ in size, commonly bud off from macroconidia Intercalary chlamydospores, 7–10μ diameter, are common (Text-fig. 3, 2).
Nectria galligena Bres. ex Strasser.
Conidia are aggregated in small white pustules or pionnotes, not more than 0.5 mm diameter, and formed among the diseased tissue of the canker on the host. Cultures are bay brown, floccose Pionnotes are poorly defined since conidiophores are sparsely branched, and are scattered in small clusters. Conidia are catenulated from terminal phialides, cylindrical, linear, sometimes curved, 1–3–4–5 septate, mostly 3–4 with apex rounded (3 septate 19–33 × 3–4μ; 4 septate 27–42 × 3–4.5μ). Chlamydospores are absent. C. mali (Allsch.) Wollenw. is the name of this conidial stage.
Nectria pinea Dingley.
In field collections pale erumpent pulvinate pionnotes are found among the perithecia. Cultures are bay brown, sometimes pale ochraceous and floccose. Pionnotes are numerous, small, formed in zones, usually on “mycelial ropes”, translucent, more or less hyaline. Conidiophores are short and sparsely branched Conidia are cylindrical, 3–4–5–6 septate, usually 4–5–6 (4 septate 59–67 × 5–6μ; 5 septate 60–81 × 5–7μ, 6 septate 60–76 × 6–7μ). Microconidia and chlamydospores are absent (Text-fig. 3, 3).
Conidial measurements of New Zealand cultures agree with Wollenweber's description (1928) of C. cylindroides rather than C. cylindroides var. tenue Wollenw. the form which he described as the conidial stage of this species. Perithecia of New Zealand material match European collections.
Nectria punicea (Kunze & Schmidt) Fr.
Erumpent sporodochia, translucent, white, but pigmented when forming perithecia, are present on the host. In cultures mycelium is floccose and cinnamon brown. Sporodochia are pulvinate, hyaline and translucent. Conidiophores are difficult to differentiate from the pseudoparenchymatous tissues of the stroma. Conidia are catenulated from terminal phialides, 0–7 septate, usually 0–3–7 septate (3 septate 27–51 × 3.5–4.5μ; 7 septate 68–88 × 4.5–5.5μ). Microconidia are common, catenulated from apices of elongated conidiophores, elliptical or fusiform, 10–14 × 4–5μ. Chlamydospores are globose and 10–15μ diameter (Text-fig. 3, 5).
Isolations from different collections yielded cultures that vary from forms typical of C. album (Sacc.) Wollenw. and of C. album var. majus Wollenw. Similar variation was not found in the morphology of the perithecia.
Nectria tasmanica Berk.
Translucent, pulvinate sporodochia, erumpent, hyaline when moist, but darkening to vinaceous brown when dry and when forming perithecia, occur on tissues of the host plant Cultures are vinaceous brown, sometimes violet, often floccose with brown aerial hyphae. Sporodochia are cream, translucent, darkening when forming perithecia. Conidiophores are short, verticillately and penicillately branched. Conidia are cylindrical, falcate, rarely oneseptate, usually 3–4–5 septate, sometimes 6 (3 septate 42–60 × 4–4.5μ; 4 septate 50–65 × 5–6μ). In cultures stored for six months at 3–5°C. conidia are 5–7 septate and 70–120 × 7–8μ. Microconidia are rare and chlamydospores are absent (Text-fig 3, 6). This conidial form agrees with descriptions of C. janthothele var majus Wollenw. the conidial form usually associated with N. mammoidea Phil. & Plowr.
Perithecia were common in cultures six to eight weeks old.
Nectria tawa Dingley.
Conidia were not found among perithecia in field collections. Cultures are fulvous or cinnamon, brown and floccose. Conidiophores are formed singly, rarely united to form pionnotei, sparsely branched, terminal phialides filiform, rather than flask-shaped. Conidia are cylindrical with rounded ends, 1–3 septate, occasionally 4–6 septate (1 septate 16–28 × 4.5–5μ; 2 septate 23–36 × 4–5μ; 3 septate 30–45 × 5–7μ). Microconidia are one or two-celled, often catenulated from a small lateral protuberance of the hypha, then aggregated into balls, 10–14 × 2.5–3.5μ. Chlamydospores are globose, intercalary or in chains 10–15μ diameter, with thickened pigmented walls (Text-fig. 3, 7) Perithecia are formed in cultures after six weeks.
Nectria westlandica Dingley.
Dark vinaceous, translucent sporodochia are found among perithecia on host tissue. Cultures are amber, sometimes streaked with orange. Sporodochia and pionnotes are common, translucent, cream, 0.25–5 mm diameter. Conidiophores are penicillately and verticillately branched; conidia are catenulated from pyriform phialides, cylindrical, sometimes falcate, often elliptical or lanceolate, 1–5 septate, rarely 6 (3 septate 48–70 × 6–7μ; 5 septate 68–80 × 7–7.5μ). Microconidia are common, sometimes catenulated from terminal phialides from conidiophores of young pionnotes; sometimes budded off from lateral protuberances of the hypha, then adhering together to form slimy spore balls 3–5.5 × 2.5–3μ. Chlamydospores are absent (Text-fig. 3, 4).
3. Species with Conidia Typical of the Form Genus Fusarium
Species of this subsection fall within two groups:—
(a) Species with small, smooth perithecia, usually caespitose on a pseudoparen-chymatous stroma, rarely scattered, and spores uniseriately arranged in the ascus.
Species studied in this group are N. laeticolor Berk, and Curt., N. vilior Starb. and N. zealandica Cke. In N. laeticolor macroconidia are classified in the section Macroconia. No macroconidia were formed in N. vilior but cultural characters are characteristic of Fusarium. In N. zealandica Cke. macroconidia are typical of the section Roseum.
(b) Species with tuberculate perithecia scattered rarely caespitose on a stroma; asci are more or less cylindrical, but spores are biseriately arranged at the apex of the ascus. Spores are lightly pigmented and striate. Included are N. haematococca Berk, and Br., N. illudens Berk., N. pulverulenta Dingley, and N. plagianthi Dingley. The conidial stage of these species falls within the section Martiella of Fusarium.
Nectria laeticolor Berk. & Curt.
Both synnemata and sporodochia are present in field collections on scale insects Cultures are white, sometimes floccose, slow growing and more or less pulvinate. Conidiophores mixed with sterile filamentous hyphae are united on a pseudoparenchymatous stroma, usually coral coloured. This stroma forms either synnemata or sporodochia. Conidia are subcylindrical, falcate, 3, but usually 5–8, rarely 9 septate, the apical cell is tapering and often curved, the basal foot cell attenuated. (5 septate 63–85 × 4–6μ; 6 septate 60–81 × 4.5–5.5μ; 7 septate 62–110 × 4–6μ)—Fusarium coccophilium (Desm.) Wollenw. & Reink. (Text-fig. 4, 1). Sterile perithecia only were formed in cultures.
Nectria zealandica Cooke.
Erumpent pulvinate sporodochia are found on bark of host, when fresh they are translucent and ochraceous but as perithecial formation takes place the stroma darkens. Cultures are floccose, often pigmented carmmie, slow growing. Conidiophores are penicillately branched, terminating in phialides and borne on translucent sporodochia. Conidia are 3–5 septate, rarely 6–7 (3 septate 27–80 × 2.5–3μ, 4 septate 45–76 × 3μ; 5 septate 48–75 × 2.5–3μ), usually sub-cylindrical, falcate, with apical cells attenuated and foot cells elongated. Microconidia and chlamydospores are absent (Text-fig. 4, 2). Sterile perithecia were found in cultures 6–8 weeks old.
Nectria vilior Starback.
No conidial stage has been found among perithecia in field collections. Single spore cultures are translucent, slimy, isabelline or pale salmon coloured. Macroconidia have not been found, but microconidia are either catenulated from terminal phialides on sparsely branched conidiophores, or budded off from protuberances on lateral walls of hyphae. They are elliptical, fusiform, cylindrical or allantoid, occasionally one-septate, otherwise unicellular, 4–9 × 1–2μ. Chlamydospores are intercalary or terminal, single or in groups, sometimes one-septate, 4–10 x
2.5–5μ. Perithecia are formed in some cultures four to six weeks old. Microconidia and cultural characters suggest a Fusarium, but as no macroconidia were formed the true nature of this conidial form could not be ascertained.
Nectria haematococca Berk. & Br.
Perithecia occur usually among a byssoid subiculum, pionnotes being present in the mycelium. Cultures are quick growing, pale vinaceous brown and usually floccose. Pionnotes and sporodochia up to 0.5 mm diameter and ochraceous, translucent, produced in zones. Conidia are cylindrical, almost straight although sometimes falcate, the apical cell rounded rather than curved, the foot cell not very pronounced, 1–7 septate commonly 3–5 septate (3 septate 25–40 × 4–5.5μ; 5 septate 40–60 × 5.5–7μ). Microconidia non-septate, sometimes one-septate, 7–12 × 2–5μ. Chlamydospores are terminal and intercalary, 7–10μ diameter. Perithecia are formed in cultures 6–8 weeks old. This conidial form is named Fusarium solani (Mart.) App. & Wollenw. var. eumartii (Carp.) Wollenw (Text-fig 4, 3).
Nectria illudens Berk.
No conidial forms have been found in field collections. Cultures are quick growing, cream, more or less floccose, pionnotes and spoiodochia are pale cream and formed in zones. Conidia are cylindrical, more or less falcate, the apical cell usually curved but often rounded, the foot cell poorly developed, 3–5 septate, occasionally 1–4 septate (3 septate 30–42 × 5–7.5μ; 5 septate 42–52 × 6–7μ). Microconidia are elliptical or fusiform, 6–9 × 2.5–3μ; chlamydospores are rarely present (Text-fig. 4, 6). The cultural characters suggest that this conidial form could be treated as a form of Fusarium solani (Mart.) App. & Wollenw. Perithecia develop in cultures 4–6 weeks old.
Nectria plagianthi Dingley.
No conidia have been found in collections on host plants. Cultures are quick growing, cream and floccose. Pionnotes and sporodochia are cream, translucent and produced in zones. Conidia are more or less cylindrical, usually falcate, the apical cell is curved, and a distinct foot cell is developed, 3–4–5 septate (3 septate 36–45 × 5.5–6μ; 4 septate 40–51 × 5–6.5μ, 5 septate 45–52 × 5–6.5μ). Microconidia are globose or pyriform, 6–15 × 3–4.5μ. Chlamydospores are globose, 6–10μ diameter (Text-fig. 4, 4).
Cultures are similar to those obtained from N. illudens but chlamydospores are common, microconidia are usually pyriform and macroconidia are narrower. This conidial form could also be treated as a variety of Fusarium solani.
Nectria pulverulenta Dingley.
In field collections a white byssoid stroma is found upon which perithecia develop together with conidiophores with few conidia. Cultures are quick growing, cream and floccose Pionnotes are pulvinate, translucent, and pale ochraceous. Conidia are arcuate rather than falcate, 3–4 rarely 5 septate (3 septate 45–52 × 5–6μ; 4 septate 40–56 × 5.5–7μ). Microconidia, 9–12 × 1.5μ are not very common. Chlamydospores are few but sometimes intercalary (Text-fig 4, 5).
As with that of other species discussed in this group the conidial stage could be regarded as a variety of F. solani