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Volume 67, 1938
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The Mould Fungi of New Zealand. I.—The Genus Penicillium.

[Read before the Manawatu Branch, September 30, 1936; received by the Editor, October 10, 1936; issued separately, June, 1937.]

The paper here presented constitutes an attempt to key and describe species of the genus Penicillium encountered to date in work on the mould fungi of New Zealand.

In common with other workers on this very important and variable genus I have found the task of delimitation of species extremely difficult. As Thom in his monumental work (The Penicillia, 1930) points out, any species name must be regarded as covering a group of varying strains rather than a fixed and constant entity. These strains may vary physiologically but should have certain constant and recognisable characters in common. Of these characters the most reliable appear to lie in the detailed morphology of the penicillus, the general morphology of which constitutes the key character of the genus. Accordingly the species names given herein are delimited and keyed solely on the morphology of the penicillus. Culture characters on a standardised synthetic medium are also given and follow, within limits, the species boundaries laid down by the morphological key. Of the morphological detais employed those have been chosen as key characters which appear to maintain the greatest degree of constancy in strain and cultural variations, and which can be most readily recognised by one who has not specialised in the group. Such characters as the numbers of the various elements constituting any particular penicillus, which vary in the same colony or in re-transfers from an original single spore isolation, have been ignored or referred to only in general description.

The adopted names are those applied to the first complete morphological description available which is in agreement with the New Zealand material, in most cases checked against type cultures obtained from abroad.

No attempt has been made to indicate synonomy and no new species have been added. The nineteen species given here represent most of the main groups of the 600 or so specific names already in existence.

The illustrations are composite drawings to scale of a fully developed typical penicillus of the species.

A glossary is added to define the sense in which special terms are employed.

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Genus Penicillium Link. Obs. Ord. plant. nat., 1809. Generic Characters.

Sterile hyphae septate, hyaline. Fertile hyphae little inflated at apex, septate, hyaline, branched or unbranched, bearing apical verticils of vase-shaped sterigmata with short tubular apices from which arise conidia in unbroken succession, forming separate unbranched chains. Conidia unicellular, hyaline or bright coloured, globose elliptical or cylindro-elliptical, not enveloped in mucus.

Key to species of Penicillium included in the present paper.
Conidiophore bearing sterigmata only:
Conidia rough:
  Apex of conidiophore vesicular. 1. P. spinulosum.
  Apex of conidiophore not vesicular. 2. P. restrictum.
Conidia smooth:
  Conidia elliptical. 3. P. Thomii.
  Conidia globose:
    Conidiophore rough. 4. P. intricatum.
    Conidiophore smooth. 5. P. frequentans.
Conidiophore bearing metullae and sterigmata:
Conidia rough:
  Conidia elliptical:
    Conidiophore rough. 6. P. Melinii.
    Conidiophore smooth. 7. P. rugulosum.
  Conidia globose:
    Conidiophore rough. 8. P. cyclopeum.
    Conidiophore smooth. 9. P. lanosum.
Conidia smooth:
  Conidia cylindro-elliptical. 10. P. Putterilli.
  Conidia elliptical:
    Conidiophore pitted. 11. P. Bialowiezense
    Conidiophore smooth:
      Conidiophore 3 μ or less in diameter. 12. P. janthinellum.
      Conidiophore 3.5 μ or more in diameter:
        Conidia 6–8 μ in long axis. 13. P. digitatum.
        Conidia 4–5 μ in long axis. 14. P. italicum.
        Conidia 3–4 μ in long axis. 15. P. expansum.
  Conidia globose:
    Conidiophore rough:
      Conidia 4.5 μ or more in diameter. 16. P. camemberti.
      Conidia about 4 μ in diameter. 17. P. roqueforti.
      Conidia about 3.5 μ in diameter. 18. P. commune.
    Conidiophore smooth. 19. P. chrysogenum.

Description of Species.

(1) P. spinulosum Thom. (Fig. 1.)

U.S. Dept. Agr. Bur. An. Ind. Bull., 118, p. 76, 1910.

Conidiophores smooth, long from substratum or short from aerial hyphae, 100–200 μ or 20–50 μ × 3 μ, with vesicular apex 5–7 μ in

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diameter, often with single divergent ramulus. Sterigmata numerous, long, 9–11 μ × 2.5 μ, tapering to apex. Conidia asperulate, globose, 3–3.5 μ, connective persistent, in long compact columns.

Czapek colony spreading, velutinous with sparse floccose areas, deep blue-green, pure green, in age dark olive-green. Margin at first definite floccose, later thin indefinite. Drops, when present, small hyaline. Odour faint in some strains, pungent in others. Reverse at first bluish white, later tinged various shades of red-brown. Media strongly stained red-brown in some strains, slightly so in others.

Isolated from soils, vascular dicolouration of potato tubers, smoked fish, bacon, surface of colloidal sulphur spraying compound, tent calico, animal hair.

(2) P. restrictum Gilman and Abbott. (Fig. 2.)

Iowa St. Coll. Jour. Sci., 1, p. 297, 1927.

Conidiophores smooth, as short branches of aerial hyphae, 10–20 μ × 2–2.5 μ, with apex very slightly enlarged. Sterigmata short, obese, 5–6 μ × 2.5 μ, with abrupt, well-defined apical tube. Conidia asperulate, globose, 2.5–2.8 μ, in loose divergent chains.

Czapek colony restricted, lanose, pulvinate, at first white, later various shades of grey to grey-green, in age to dusky purple. Margin definite, lanose, in old colonies as raised white peripheral zone surrounding depressed grey-green central area. Drops hyaline to vinaceous. Odour absent in most strains, pungent in one. Reverse at first white, remaining so or later tinged shades of red-brown to deep port-wine with media stained in same colours.

Isolated from soils, vascular discolouration of potato tubers and stems.

(3) P. Thomii Maire. (Fig. 3.)

Bul. Soc. Hist. Nat. Afr. du Nord, 8, pp. 189–192, 1917.

Conidiophores smooth, long from substratum or short from aerial hyphae, up to 300 μ or 50–60 μ × 2.5 μ, with vesicular apex 5–6 μ in diameter. Sterigmata numerous, 7–9 μ × 2.5 μ, clustered on apical surface, with abrupt, well defined, apical tube. Conidia smooth, elliptical, ovate to almost globose, 2.5 μ to 3.5 μ in long axis, varying with the strain, in divergent chains and loose columns. Sclerotia numerous, ovate, 100–400 μ in long axis, pink by reflected light, deep yellow by transmitted light. Asci not observed.

Czapek colony spreading, at first lanose, later thin velutinous, white, turning blue-green quickly in some strains, slowly or not at all in others. Early forming concentric zones of pink sclerotia. Drops numerous, small, hyaline. Margin at first definite lanose, later indefinite. Odour not observed. Reverse opaque white, later salmon in zones. Not staining media.

Isolated from forest and mountain heath soils, sawn Podocarpus timber.

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(4) P. intricatum Thom. (Fig. 4.)

U.S. Dept. Agr. Bur. An. Ind. Bull., 118, pp. 75–76, 1910.

Conidiophores verrucose, terminal to long trailing hyphae generally with one or more divergent ramuli below apex, or as short branches arising from ropes of intertwined hyphae, 14–35 μ × 2.2–2.8 μ, with apices very slightly enlarged. Sterigmata smooth, short, 6 × 1.5 μ, in tight packed verticils of 5–8, with well-marked apical tube. Conidia smooth, at first elliptical, finally globose, 2.5–3 μ, showing connective, in short loose to divergent chains.

Czapek colony moderately spreading, floccose, with tufts of white mycelium, pale grey-green turning steel-grey and finally ferruginous grey to nearly purple. Margin wide, floccose, somewhat indefinite. Drops not observed. Odour not observed. Reverse opaque chinawhite tinged in areas canary-yellow. Not staining media.

Isolated from decayed Gladiolus corm.

Thom's original description of P. intricatum does not indicate roughness of the conidophore, and the sterigmata, as given, are somewhat larger than those of the present strain. In other respects, however, the two descriptions are sufficiently close to justify adoption of the name.

(5). P. frequentans Westling. (Fig. 5.)

Arkiv. for Botanik, 11, pp. 58. 133–134, 1911.

Conidiophores smooth, long from substratum or short from aerial hyphae, 200–350 μ or 30–80 μ × 2.5 μ, with vesicular apex 4–5.5 μ in diameter. Ramuli usual in some strains, scarce or absent in others. Sterigmata numerous, crowded, 7–8 μ × 2–2.5 μ, with very short apical tube. Conidia smooth, globose, 3–3.5 μ, connective evident, in very long compact to somewhat loose columns.

Czapek colony spreading, at first lanose, becoming velutinous quickly in some strains, tardily in others, blue-green to fuscous-green. Margin definite lanose. Drops not observed. Odour faint or none. Reverse cloudy white, tinged yellow, later in zones of orange to dark red in most strains, yellowish green in others. The former strains strongly staining the media red-brown, the latter strains hardly at all.

Isolated from arable and pasture soils, exposed plates in butter factories and meat works, discoloured Cheddar cheese, tank and stream-water, frass in insect tunnels in timber.

(6) P. Melinii Thom. (Fig. 6.)

The Penicillia, p. 273, 1930.

Conidiophores verrucose, from substratum, 150–250 μ × 3.5 μ, somewhat vesicular at apex. Metullae verrucose, 8–11 μ × 3 μ, in verticils of 3 to 5, somewhat divergent. Ramuli, when present, verrucose, divergent, 18–30 μ × 3.3 μ, bearing sterigmata only. Sterigmata 8–10 μ × 2.5 μ, in verticils of 5–8, with well-defined apical tube, apices somewhat divergent. Conidia asperulate, ovate or broadly elliptical, 2.5–3 μ in long axis, in long loose divergent chains.

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Czapek colony spreading, velutinous to mealy, with scattered floccose overgrowth, at first blue-green, later dark olive-green. Margin at first definite floccose, later indefinite velutinous. Drops not observed. Odour strong, mouldy. Reverse at first creamy-white tinged yellow, later tinged yellow-brown. Not staining media.

Isolated from arable soil.

(7) P. rugulosum Thom. (Fig. 7.)

U.S. Dept. Agr. Bur. An. Ind. Bull., 118, pp. 60–61, 1910.

Conidiophores smooth, from substratum or aerial hyphae, 100–200 μ × 2.5–3 μ. Metullae smooth, 8–10 μ × 2.5–3 μ, generally in symmetrical verticils of 3 or 5. Sterigmata 8–10 μ × 2.5 μ, crowded at base with tapering somewhat divergent apices. Conidia asperulate, ovate-elliptical, 3.5 μ × 3 μ, with persistent connective, in loose divergent chains.

Czapek colony compact, at first floccose white, later developing areas of yellowish green, turning dark green, finally brown, with irregular floccose yellowish overgrowth. In age, rough, mealy, dark brown. Margin at first definite, floccose, tinted yellow, later spreading indefinite. Drops small hyaline. Odour weak to pungent. Reverse creamy white, later strongly tinged yellow, in one strain with bright orange bands. Staining media.

Isolated from soils, paper lining to lid of candy bottle.

(8) P. cyclopeum Westling. (Fig. 8.)

Arkiv. for Botanik, 11, pp. 55–56, 90–92, 1911.

Conidiophores verrucose, long from substratum, many intertwined in fascicles, 3.5–4 μ in diameter. A single semi-divergent ramulus generally present. Metullae verrucose, 9–12 μ × 3–3.5 μ, with somewhat enlarged apices. Sterigmata obsecurely verrucose, 7–10 μ × 3 μ with well-defined apical tube. Conidia asperulate, globose, 3.8 μ-4.5 μ, in divergent or tangled chains.

Czapek colony spreading, deep, fasciculate, blue-green becoming brown in age. Margin wide, at first white floccose, later in raised rough blue-green zones. Drops numerous, hyaline. Odour strong, mouldy. Reverse at first opaque white with yellow areas, later brown centre with crinkled blue-white margin. Not staining media.

Isolated from potato tuber, “sap-stained” Podocarpus timber.

(9) P. lanosum Westling. (Fig. 9.)

Arkiv. for Botanik, 11, pp. 55, 97–99, 1911.

Conidiophores smooth, long from substratum, up to 900 μ × 3–3.5 μ. Ramuli generally present, smooth, variable in length, somewhat divergent, bearing metullae. Metullae smooth, 10–14 μ × 3 μ, somewhat enlarged at apex, in symmetrical verticils, generally of 5. Sterigmata smooth, 7–8 μ × 2 μ, with well-marked apical tube. Conidia delicately asperulate, at first almost pyriform, later globose, somewhat irregular in outline, 2.5–3 μ, with very evident connective, in long loose tangled chains.

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Czapek colony spreading, lanose, pulvinate, at first white, later grey-green to yellowish brown. Margin at first white, lanose, definite, later becoming velutinous, spreading, with indistinct floccose zones. Drops numerous hyaline. Odour faint. Reverse at first white, tinged yellow, later orange-brown to almost black in areas. Slightly staining media.

Isolated from vascular discolouration of potato tuber, exposed plate in dairy factory.

(10) P. Putterillii Thom. (Fig. 10.)

The Penicillia, pp. 368–369, 1930.

Conidiophores verrucose, short from aerial hyphae and ropes of hyphae, 20–150 μ × 3.5 μ, apex somewhat enlarged. Ramuli generally present, verrucose, somewhat appressed, 14–20 μ × 3 μ. Metullae verrucose, 10–12 μ × 2.8 μ. Sterigmata smooth, 9–12 μ × 1.8 μ, tightly packed in verticils of 5 to 8, tapering to apex. Conidia smooth, at first cylindrical, later becoming cylindro-elliptical, 3.5–4 μ × 1.5–2 μ, in long loose columns and tangled masses.

Czapek colony spreading, floccose, thin, white to flesh-coloured. Margin definite floccose. Drops not observed. Odour faint. Reverse at first creamy white later deeply stained reddish brown, at centre almost black. Slightly staining media.

Isolated from “sap-stained” timber of Beilschmiedia tawa and Nothofagus Menziesii.

(11) P. bialowiezense Zaleski. (Fig. 11.)

Bull. Acad. Pol. Sci. Math. et Nat., Ser. B, pp. 450, 451, 1927.

Conidiophores irregularly and sparsely pitted, long from substratum, up to 700 μ × 4.5–5 μ, with enlarged apex. Ramuli pitted, appressed, 20–30 μ × 4–4.5 μ, with enlarged apex. Metullae pitted, in two series, 10–12 μ × 3.5 μ and 7–8 μ × 3 μ, apices enlarged. Sterigmata obscurely pitted, 7 μ × 2.2 μ, with short, well-defined, apical tube. Conidia smooth, elliptical, 5 μ × 3.5 μ when ripe, connective not defined, in long parallel chains becoming evenly divergent in length, thus forming a wide spreading brush springing from a narrow base.

Czapek colony compact, mealy, grey-green to dark green, later spreading, velutinous, in light and dark zones, with scattered floccose yellowish tufts of overgrowth, finally all brown. Margin definite abrupt, at first floccose, narrow, white, later undifferentiated. Drops hyaline to yellow. Odour not observed. Reverse at first bright orange with narrow yellow margin, later with darkened, almost black, zones. Staining media red-brown.

Isolated from decayed potato tuber, decayed sporophore of a Boletus.

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(12) P. janthinellum Biourge. (Fig. 12.)

Monogr. La Cellule, 33, fasc. 1, pp. 258–260, 1923.

Conidiophores smooth, long from substratum or short from aerial hyphae and ropes of hyphae, 2.5–3 μ in diameter, with apex somewhat enlarged. Ramuli generally absent. Metullae smooth, 9–11 μ × 2.2 μ, generally in symmetrical verticil of 5, somewhat divergent, apices slightly enlarged. Sterigmata 9–10 μ × 2 μ, tapering gradually to apex, somewhat divergent. Conidia smooth, at first narrow elliptical, later broadly elliptical, almost globose, about 3 μ in long axis, connective distinct and persistent, in long loose to divergent chains.

Czapek colony spreading, at first floccose, white, soon yellowish green, later mealy to velutinous, dull green, with isolated tufts of yellowish tomentum. Margin indefinite, yellowish green. Drops not observed. Odour faint. Reverse cloudy yellowish green, tinged pink to claret in zones and areas in some strains [ unclear: ] not in others. Not staining media.

Isolated from arable, pasture, and forest soils, germinating seeds, discoloured Cheddar cheese, case timber, exposed plate in meat works.

I have followed Thom (The Penicillia, 1930) in adopting Biourge's name although the latter's description of P. janthinellum hardly agrees with Thom's Soil Series, published in Pratt's Relations of Soil Fungi to Potato Diseases, 1918, to which the New Zealand strains apparently belong. If one accepts Thom's observation that “the conidia may be either smooth or delicately roughened or both conditions in the same strain,” then no morphological grounds exist for separation from P. rugulosum described by Thom in 1910.

(13) P. digitatum Saccardo. (Fig. 13.)

Sylloge Fungorum, IV, p. 78, 1884.

Conidiophores smooth, from substratum, very variable in length, 4–5 μ in diameter, on fruit often intertwined in fascicles. Ramuli smooth, variable, somewhat divergent. Metullae smooth, few and variable in number, 10–14 μ × 3.5 μ. Sterigmata few, large, 12–14 μ × 3 μ, with well-developed apical tube. Conidia smooth, at first somewhat cylindrical, later elliptical, very variable in size, up to 8 μ × 5 μ, in diverging chains, connective not evident. The whole penicillus appearing coarse and irregular.

Czapek colony very thin and weak. On potato-dextrose-agar spreading, mealy, grey-green, soon turning olive-green. Margin definite. Drops not observed. Odour pungent. Reverse dusky cream. Not staining media. Two strains, isolated from oranges, produced in three weeks conspicuous, olive-green mushroom shaped coremia, carried on white stalks 300–500 μ in diameter, projecting about the media for 500–1000 μ and continued for several millimetres as a rhizome-like structure into the media.

On citrus fruit spreading rapidly following inoculation, producing a general soft rot. Floccose tufts appear on the epidermis surrounding the point of inoculation, at first white, soon turning

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olive-green to form thick dusky green masses of spores surrounded by a wide floccose white area. (See Plate III.) Inoculated to pear fruit the species caused a generalized internal soft rot with a few scattered lanose tufts at first white, later olive-green, on the surface. Later developing a plentiful crop of the stalked coremia mentioned above. On apples all inoculations proved negative.

Isolated from citrus fruits. This is the predominant mould to develop on citrus fruit after leaving the orchard.

(14) P. italicum Wehmer. (Fig. 14.)

Hedwigia, 33, pp. 211–214, 1894.

Conidiophores smooth, long from substratum, 3.5–4 μ in diameter, on fruit often intertwined in fascicles. Ramuli smooth, appressed, 14–16 μ × 3–3.5 μ. Metullae smooth, appressed, 10–12 μ × 3 μ, usually in verticils of 5 on main axis, less on ramuli. Sterigmata smooth, 9–11 μ × 2.5 μ, with well-developed apical tube, in compact verticils, generally of 5. Conidia at first cylindrical, later elliptical, somewhat variable in size, generally about 4 μ × μ but some up to 5 μ × 3.5 μ in long loose chains. Connective not evident. Sclerotia ovate, about 350 μ in long axis, observed only in certain strains.

Czapek colony spreading, mealy, blue-green turning grey-green in age. Margin wide, white, floccose, definite. Drops not observed. Odour pungent. Reverse cream to brown. Not staining media.

On citrus fruit spreading moderately, causing a soft rot. Floccose tufts soon appear on the epidermis of the fruit in zones about the point of infection, at first white but soon turning deep blue from centre of lesion outwards. (See Plate III.) On pears causing a generalized soft rot with isolated coremia on epidermis. On apples can establish and sporulate on injured tissues bordering punctures but does not spread or cause a rot.

Isolated from citrus fruits.

(15) P. expansum Link. (Fig. 15.)

Obs. in Ord. Plant. Nat., p. 17, 1809.

Condiophores smooth, long from substratum, 3.5–4 μ in diameter, on fruit nearly all intertwined in fascicles, in culture or on other substrata less so, more or less losing the property after several transfers. Ramuli smooth, appressed. Metullae smooth, appressed, 10–14 μ × 3 μ. Sterigmata smooth, 7–9 × 2.5 μ, narrowing only slightly at apex. Conidia at first ovate-cylindrical, later broadly elliptical, 3.5 μ × 3.2 μ, in long loose chains. Connective not evident. The type of penicillus illustrated is typical of that found as a member of a fascicle on fruit. The same strains in culture, and strains isolated from other sources, produce larger numbers of metullae and sterigmata in the verticil, and resemble the normal typical “asymmetric” penicillus illustrated for P. italicum.

Czapek colony of isolation from apple, spreading, mealy, in concentric zones, blue-green to grey-green, and finally brown. Margin

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at first definite, floccose, white, later indefinite, spreading, with scattered coremia. Strains from other sources, and apple strains after several transfers, show more or less suppression of the coremial or fascicular character. Drops hyaline. Odour pungent, characteristic of rotten apples in strains from fruit, moderate to faint in others. Reverse, reddish brown, speckled, with an iridescent sheen. Staining media.

On pomaceous fruits produces a rapid brown rot, with rings of large blue-green coremia about point of infection. On citrus fruit produces the same symptoms but the infected areas develop very slowly. (See Plate III.)

Isolated from pomaceous fruits, mangel, pumpkin, Gladiolus corm, preserves, chutney, Cheddar cheese, sporophore of Gasteromycete, bread, manufactured tobacco, Pinus cones, case timber, soil under bakehouse, exposed plates in laboratory, factories and stores.

(16) P. camemberti Thom. (Fig. 16.)

U.S. Dept. Agr. Bur. An. Ind. Bull., 118, pp. 50–52, 1910.

Conidiophores sparsely verrucose, long from substratum or short from aerial hyphae, very variable in length 3–4 μ in diameter. Development of elements of penicillus very irregular. Ramuli, when present, verrucose, 16–22 μ × 3 μ, appressed or somewhat divergent. Metullae verrucose, smooth, irregular in length, 1, 2, or 3 to the verticil, seldom in more than one series, somewhat divergent, 8–14 × 3 μ. Sterigmata smooth, 1, 2, or 3 to the verticil, 9–11 × 2.5 μ, variable in shape. Conidia smooth, at first elliptical, later globose or irregular in shape, variable in size, 4.5–6 μ, in loose divergent chains.

Czapek colony spreading, deep, lanose, white, tardily tinged grey-green. Margin definite, white, lanose. Drops not observed. Odour faint. Reverse opaque creamy white. Not staining media.

Isolated from Camembert cheese.

(17) P. roqueforti Thom. (Fig. 17.)

U.S. Dept. Agr. Bur. An. Ind. Bull., 82, pp. 35–36, 1906.

Conidiophores verrucose, generally with sparse rather large warts, from substratum or aerial hyphae 80–200 μ × 4.5–5 μ. Penicilli from simple monoverticillate to complex pluriverticillate. Ramuli verrucose, appressed or somewhat divergent [ unclear: ] 16–26 μ × 4.5 μ. Metullae sparsely verrucose or smooth, appressed, in verticils of 1 to 5, 12–16 μ × 4 μ. Sterigmata smooth, 10–12 μ × 3 μ, narrowing abruptly to blunt apex, in verticils of 1 to 5. Conidia smooth, at first elliptical, later globose, 4–4.5 μ, in long loose chains, maintaining a loosely columnar structure in mass.

Czapek colony spreading, thin, velutinous, blue-green turning dull green, purplish brown in age. Margin arachnoid or stellate, from radiating bands of sub-surface and surface mycelia of varying diameter, some up to 7 μ. Drops not observed. Odour pungent,

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aromatic. Reverse at first cloudy white, later tinged various shades of green becoming dark green to almost purple with age. Not staining media.

Isolated from Stilton, Wensleydale and Cheddar cheese (generally confined to internal crevices in the latter type of cheese, causing the so-called “Stilton-defect”), butter, pickles. One strain isolated from discoloured Cheddar cheese, after annual transfer in stock on potato-dextrose-agar slants for 3 years, lost all colour and the following year produced small (30–50 μ) globose sclerotia in 3 weeks on Czapeck agar. The conidial structures had become very scanty, abnormal and defective in elements, spore-size and shape remaining constant.

(18)P. commune Thom. (Fig. 18.)

U.S. Dept. Agr. Bur. An. Ind. Bull., 118, pp. 56–57, 1910.

Conidiophores coarsely verrucose, arising from substratum, rarely from aerial hyphae, long, up to 850 μ × 4 μ. Penicilli large, pluriverticillate. Ramuli verrucose, appressed, usually single asymmetric, sometimes paired, or alternately from a lower node 16–35 μ × 3.5–4 μ. Metullae verrucose, often in two series, the lower series 12–14 μ × 3.5 μ, the upper 10–12 μ × 3 μ, closely appressed and crowded in the verticil, some strains showing one series only. Sterigmata smooth, 8–10 μ × 3 μ, narrowing abruptly to blunt apex. Conidia smooth, at first elliptical, later globose, mature spores very constant at 3.5 μ in diameter in most strains, exceptionally up to 4.5 μ. In tangled chains forming thick masses.

Czapek colony somewhat restricted at first, later spreading, floccose, quickly blue-green, turning dull green, later purplish brown. Surface of colony remains rough to mealy often with pronounced ridged zones. Margin at first definite, floccose, white, later becoming thin and spreading. The giant hyphae, 6–7 μ in diameter, characteristic of P. roqueforti, are also sometimes present in this species. Drops numerous hyaline. Odour very strong in most cultures, mouldy. Reverse opaque white, lightly tinged greenish yellow to rusty brown in irregular areas. Not staining media.

Isolated from Cheddar cheese, milk, cream, dairy factory wash water and air, air of milking sheds, meat, bacon, lard, dried vells, hides, bread, potato-tuber, swede and mangel bulbs, germinating seeds.

This is the commonest green mould on foodstuffs in New Zealand. In an investigation of the mould flora of New Zealand Cheddar cheese factories, carried out in 1932, of samples from 58 factories 53 yielded P. commune only (at that time incorrectly indentified by me as P. puberulum), 4 P. roqueforti only, 5 both P. commune and P. roqueforti, 2 Penicillia intermediate in character between P. commune and P. roqueforti, and 3 other species of Penicillia. There appears to be no clear morphological distinction between this species and P. roqueforti.

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(19) P. chrysogenum Thom. (Fig. 19.)

U.S. Dept. Agr. Bur. An. Ind. Bull., 118, pp. 58–60, 1910.

Conidiophores smooth, arising from substratum, occasionally from aerial hyphae, 100–400 μ × 4–5.5 μ, apex not enlarged. Ramuli smooth, generally single, sometimes paired, appressed 16–22 × 4 μ, apices not enlarged. Metullae smooth 12–14 × 3.5 μ,. tightly packed in whorls of 5 on main conidiophore, often reduced to 2 on ramulus. Sterigmata smooth, 8–10 μ, in tight packed whorls of 5 to 7, narrowing abruptly to blunt apex. Conidia smooth, at first elliptical, later globose, about 3 μ, in chains at first ascending parallel, later tangled, connective not evident.

Czapek colony slow to moderate in growth, somewhat raised, floccose in central areas, merging into velutinous-mealy periphery, blue-green becoming dull green to almost brown with age. Margin at first white floccose definite, later indefinite velutinous. Drops hyaline. Odour in most strains strong mouldy, almost absent in some. Reverse opaque white, tinged yellow, in some strains darkening to orange. Media lightly stained in some strains, not stained in most.

Isolated from soil, air-exposed plates in dairy factories and meat works, black spots on beef dripping, green mould on banana fruit, vascular discolouration of potato tuber, green mould on leather shoes and shoe polish, frass in insect tunnels in hardwood.

Literature Consulted.

Biourge, Ph., 1923. Les moississures du groupe Penicillium Link., La Cellule, vol. 33, fasc. 1, 331 pp.

Saccardo, P. A., 1886. Sylloge Fungorum, vol. 4, pp. 78–85.

Sopp, O. J., 1912. Monographie der Pilzgruppe Penicillium, 208 pp.

Thom, C., 1910. Cultural studies of species of Penicillium, U.S. Dept. Agr. Bur. An. Ind. Bull., 118, 109 pp.

— 1930. The Penicillia, 643 pp.

Thom, C., and Church, M. B., in Pratt, O. A., 1918. Soil Fungi in relation to diseases of the Irish potato in Southern Idaho, Jour. Agr. Res., vol. 13, pp. 93–99.

Thom, C., and Church, M. B., 1926. The Aspergilli, 272 pp.

Wehmer, C., in Lafar, F., 1911. Techinical Mycology. 2, pp. 246–258. (Transl. Salter, T.C.)

Glossary.

Asperulate: Covered with small projections.

Conidiophore: Specialized hypha bearing the penicillus.

Connective: Outer wall of cell budded from apex of sterigma, within which successive conidia are formed, which persists as means of attachment between conidial units in the chain. In some species the connective becomes attenuated, and readily observed, in others it is not apparent, the conidia remaining in close juxtaposition.

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Coremium: A raised structure composed of compacted masses of penicilli constricted to a tight rope or stalk at the base, spreading at the conidiabearing apex.

Gzapek colony: Surface growth produced by mass inoculation of Czapek's solution agar in petri-dish culture, incubated at 21° C., made up to the following formula (from Thom, The Penicillia, p. 42, 1930):—Water 1 litre; Sodium nitrate 2 grm.; Potassium phosphate 1 grm.; Magnesium sulphate 0.5 grm.; Agar—about 15 grms.; Potassium chloride 0.5 grm.; Ferrous sulphate trace; Sucrose 30 grms.

Definite margin: Edge of growing colony clear-cut. Submerged hyphae hardly in advance of aerial hyphae.

Fascicle: An interlacing mass of conidiophores, not consolidated into a solid rope.

Floccose: Woolly tufts, intertwined aerial hyphae in tufts rather than as an even layer.

Indefinite margin: Edge of growing colony diffuse, not clear cut. Submerged hyphae generally much in advance of aerial hyphae.

Lanose: Woolly, an even layer of fine cotton-wool-like interlacing hyphae.

Margin: Peripheral zone of petri-dish colony.

Metulla: Member of a verticil of elongated cells budded from apex of conidiophore, ramulus, or a previously formed metulla and bearing sterigmata.

Penicillus: The fructification of a Penicillium including ramuli, metullae, sterigmata and conidia.

Ramulus: A single branch budded from apex of the second, third, or fourth cell of conidiophore below the apical cell. In origin there is no difference between a ramulus and a metulla but in most Penicillia the first (in time) lateral bud from a developing conidiophore remains single, developing parallel to the subsequent development of the latter, and, in this paper, referred to as a ramulus.

Reverse: Petri-dish colony as viewed from below.

Sclerotium: A compact, pseudoparenchymatous, globose or oval mass of interwoven hyphae.

Sterigma: The conidium-bearing terminal cell of a penicillus.

Velutinous: Flat, even, velvety surface.

Verrucose: Surface showing blunt projections as warts or folds.

Vesicular: Conspicuously swollen.

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Fig. 1—P. spinulosum. Fig. 2—P. restrictum. Fig. 3—P. Thomii. Fig. 4—P. intricatum. Fig. 5—P. frequentans. Fig. 6—P. Melinii. Fig. 7—P. rugulosum. Fig. 8—P. cyclopeum. Fig. 9—P. lanosum. Fig. 10—P. Putterilli. All × 1000.

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Fig. 11—P. bialowiezense × 500. Fig. 12—P. janthinellum × 1000. Fig. 13—P. digitatum × 1000. Fig. 14—P. italicum × 1000. Fig. 15—P. expansum × 1000. Fig. 16—P. camemberti × 500. Fig. 17—P. roqueforti × 500. Fig. 18—P. commune × 500. Fig. 19—P. chrysogenum × 500.

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Inoculations of Orange and Lemon. Upper: P. expansum Centre. P. italicum. Lower: P. digitatum.