Accepted Species of Karlingiomyces

 

 

1. Karlingiomyces asterocystis (Karling)

Sparrow, Aquatic Phycomycetes, 2nd ed., p. 560, 1960. FIGURES 1-5

Karlingia asterocysta Karling, Mycologia 41: 509, Figs. 9-19, 1949.

Vegetative: Thallus epibiotic on chitinous substrates. Reproductive: Sporangium hyaline, smooth-walled, spherical, oval, pyriform, oblong, fusiform, elongate or irregular, diameter 12-110 µ m (usually toward the larger end of the range). Rhizoidal system: Extensive, branching, each of the main axes up to 18 µ m in diameter. Zoospore discharge: Zoospore discharge papillae 1 to 4, low, often barely rising above the sporangial surface (more distinct, or relatively elevated, as much as 11 µ m high on small sporangia), 8-14 µ m in diameter; with a conspicuous hyaline area beneath, extending up to 16 µ m into the sporangium; exo-operculum, convex though shallow, hyaline, diameter up to 14 µ m; zoospores discharged en masse through opening left by expressed operculum, swarming briefly in an evanescent vesicle, then dispersing. Zoospore microscopic: Zoospore spherical, hyaline, 4.2-4.6 µ m in diameter, with a single, relative large (0.7-1.2 µ m) hyaline refractive lipid globule; flagellum 24-26 µ m long. Resting spore: Subspherical, oval, oblong, angular or irregular, 12-30 µ m in diameter, the contents hyaline; spore wall becoming dark greenish-brown, becoming more or less covered with blunt to somewhat pointed, straight or slightly curved (at the tip) peg-like “spines”; these pegs 4-8 µ m in height, 2-4 µ m broad at base, smooth or rarely verrucose, 22-60 per spore; pegs becoming dark greenish-brown (as the spore wall); resting spore germination not observed, though resting spores are sometimes found in greater numbers than sporangia. Ecology and Distribution: Saprophytic on chitinous material, such as insect exuviae; readily baited on shrimp exoskeleton (Murray & Lovett 1966); isolated from soil and water; US, Maryland (cf. Karling 1949, Sparrow 1960), Louisiana (cf. Murray & Lovett 1966); NEW ZEALAND (Karling 1967).

Type: No type specimen, as can be determined, was specifically designated or deposited, either by Karling or Sparrow. In accordance with Articles 8 and 9 of the International Code of Botanical Nomeclature (ICBN 2000), an illustration may be utilized as the type. Hence, Karling’s illustration (Figs. 9-19) of (the basionym) Karlingia asterocysta Karling (Mycologia 41: p. 507, 1949) is accepted as the holotype of Karlingiomyces asterocystis (Karling) Sparrow (1960). These figures are also the type of the genus name Karlingiomyces (cf. Article 10, ICBN 2000). Original material of Karlingia asterocysta was isolated from soil and water, Charles County, Maryland.

Discussion: Karling (1967) attempted to return this species to Karlingia and used the epithet spelling “asterocystis” (applied to Karlingiomyces by Sparrow, 1960); if used as a final name element (e.g., “astero-cystis”), “-cystis” is permissible in either case (Stearn 1983). Regardless, the shallow but definite exo-opercula (Fig. 1)—no endo-opercula being evident in this case—support placement of this species in Karlingiomyces.

2. Karlingiomyces curvispinosus (Karling)

Sparrow, Aquatic Phycomycetes, 2 nd ed., p. 560, 1960. FIGURES 6-9

Karlingia curvispinosa Karling, Mycologia 41:511, Figs. 20-35, 1949.

Vegetative: Thallus epibiotic on chitinous substrates, the substrate sometimes becoming discolored. Reproductive: Sporangium quite variable, sessile or occasionally stalked, subspherical, oval, pyriform, obclavate, oblong, or elongate, sometimes apiculate, 8-160 µ m diameter, more or less hyaline, relatively thin- and smooth-walled, occasionally with in-growths (plugs) of wall material. Rhizoidal system: Much branched; usually developed from several main axes (formed at different points on the sporangium), these relatively coarse in appearance, up to 16 µ m in diameter. Zoospore discharge: Zoospore discharge papillae 1 to 3, prominent to relatively obscure, conical or low and dome-shaped; exo-operculum 6-18 µ m broad, somewhat convex, thin or slightly thickened, hyaline, ephemeral after dehiscence; zoospores not contained in a vesicle upon release from sporangium, but may be temporarily immersed in a granular matrix. Zoospore microscopic: Zoospores hyaline, spherical, 3.8-4.2 µ m in diameter, with one prominent, hyaline refractive globule 0.6-0.8 µ m broad; flagellum 10-13 µ m long. Resting spore: Spherical, oval, or slightly angular to somewhat irregular, 6-21 µ m in diameter, contents granular, sometimes developing a small vacuole; young resting spore often surrounded by a hyaline zone of amorphous material; pegs or spines appearing to gradually develop in this hyaline layer; pegs or spines eventually becoming numerous, covering the resting spore surface, curved (somewhat hook-like) and pointed; resting spore more rarely merely echinulate, verrucose or smooth; color of resting spore eventually greenish- or dark-amber or brownish; resting spore, functioning as a prosporangium in germination. Ecology and Distribution: Soil or water; saprophytic on chitin or keratin substrates; often rapid and prolific in growth (readily cultured); resting spores sometimes imparting a distinctive greenish-amber or darkened coloration to the substrate; US, Maryland (cf. Karling 1949; Sparrow 1960), Maine (collections by J. E. Longcore, JEL 93 and JEL 223, are probably this species; however, resting spores, critical to determination, were not observed); NEW ZEALAND (Karling 1967).

Type: Karling’s illustration (Figs. 20-35; Mycologia 41: p. 507 and 512, 1949) of Karlingia curvispinosa is accepted as the type of Karlingiomyces curvispinosus (Karling) Sparrow (1960). Original material isolated from soil and water in a ravine near the Monocacy River at Frederick, Maryland .

Discussion: Karling (1967) noted that New Zealand specimens of K. curvispinosus were identical with those from the United States , except for the “lack of a…clear zone” surrounding the developing resting spore—perhaps a “culture” or “artifact”-based observation.

3. Karlingiomyces dubius (Karling)

Sparrow, Aquatic Phycomycetes, 2 nd ed., p. 561, 1960. FIGURES 10-14

Karlingia dubia Karling, Mycologia 41:513, Figs. 36-51, 1949.

Vegetative: Thallus epibiotic on chitinous substrates. Reproductive: Sporangium subspherical, oval, pyriform or oblong, variable in diameter (15-240 µ m), hyaline, smooth-walled. Rhizoidal system: Extensive, copiously branched; the several main rhizoidal axes each attaining a diameter of 12 to 16 µ m, usually thick-walled, with a number of regular or irregular constrictions which may in places appear to virtually occlude the rhizoidal lumen (pseudo-catenulate). Zoospore discharge: Zoospore discharge papillae 1 to 4, low to relatively prominent, 12-34 µ m in diameter, subtended by a more or less hemispherical hyaline zone that may extend as much as 16 µ m into the sporangium; exo-operculum convex but shallow, 10-30 µ m in diameter, relatively uniform in thickness, usually dehiscing prior to zoospore discharge and remaining for a time “perched” on hyaline material of the exit papilla (which appears as a “cushion”); zoospores eventually expressing the operculum, emerging together in a gelatinous “matrix” of material, but soon dispersing.

Zoospore microscopic: Zoospores spherical, hyaline, 6-6.5 µ m in diameter, with a single, basal, relatively large (2-2.3 µ m) hyaline globule apparent; flagellum long (32-35 µ m), but at first (upon zoospore discharge) obscure and coiled around body of zoospore, then uncoiling for motility and dispersal. Resting spore: Spherical, oval, elongate or somewhat angular, 8-20 µ m in diameter, with relatively coarse, granular contents; resting spore wall smooth to rugose or verrucose, becoming dark brown; resting spores formed as result of sexual process (Willoughby 1957), remnants of the two fused gametangial bodies sometimes remaining evident externally on the resting spore (Dogma 1974); resting spore functioning as a prosporangium in germination (Dogma 1974). Ecology and Distribution : Soil and water; saprophytic on chitinous residue; readily baited, e.g., on shrimp exoskeleton; US, Maryland (cf. Karling 1949, Sparrow 1960); ENGLAND (Willoughby 1957, 1964); AUSTRALIA, State of Victoria (Willoughby 1965), New South Wales (recent observation P.M. Letcher); NEW ZEALAND (Karling 1967); MALAYSIA, Singapore (Dogma 1974).

Type: Karling’s illustration (Figs. 36-51; Mycologia 41: p. 512, 1949) of Karlingia dubia is accepted as the type of Karlingiomyces dubius (Karling) Sparrow (1960). Original material isolated from Calvert County , Maryland .

Discussion: Some disagreement has occurred over taxonomic placement of
Karlingiomyces dubius. Willoughby (1957) recognized Karling’s (1949) Karlingia dubia, but confirmed the unique (“raised”) exo-operculum ( Willoughby ’s Figs. 3C,E). However, Sparrow (1960) transferred this species to his new genus, Karlingiomyces, on the basis of definitive exo-operculation. Although Sparrow selected K. asterocystis as the type of Karlingiomyces, it was only K. dubius that he elected to illustrate. Karling (1967) sought to return “K. dubia”, among several taxa, to Karlingia. Dogma (1973), in a delimiting viewpoint of genera (based on differences in operculation), recognized all three genera of the “rhizophlyctoid assemblage” (Rhizophlyctis, Karlingia and Karlingiomyces). Dogma (1974) accepted K. dubius as exo-operculate, and as belonging to Karlingiomyces. We concur with Sparrow’s and Dogma’s placement of this species in Karlingiomyces.

4. Karlingiomyces marylandicus (Karling)

Sparrow, Aquatic Phycomycetes, 2 nd ed., p. 562, 1960.
          Spelling of the epithet given as “marilandicus” by Sparrow (1960). FIGURES 15-17

Karlingia marylandica Karling, Mycologia 41:518, Figs. 70-78, 1949.

Vegetative: Extramatrical on cellulose substrates. Reproductive: Sporangium spherical, oval, pyriform, oblong to somewhat elongate or irregular, 20-85 µ m in diameter, the wall smooth and often somewhat thickened (1.8-2.6 µ m thick). Rhizoidal system: Rhizoid axes usually emerging from several different points on the sporangium (occasionally monorhizoidal, cf. Karling 1966), relatively coarse in appearance, up to 12 µ m broad, irregularly constricted, the walls somewhat thickened, ultimately extensively branched. Zoospore discharge: Zoospore discharge papillae 1 or 2, varying from nearly sessile to elongate and tube-like (the “tube” straight, irregular or contorted), 10-15 µ m broad, 10-205 µ m long; exo-operculum up to 17 µ m in diameter, convex, thin or uniformly thickened; endo-opercula sometimes also observed; zoospores emerging temporarily as a globular mass in a slimy matrix. Zoospore microscopic: Zoospores hyaline, spherical, either 5.5-6 µ m or 2-3.5 µ m (apparently of two sizes in the same sporangium), with a single, relatively large, hyaline refractive globule (0.8-2.8 µ m broad). Resting spore: Not observed. Ecology and Distribution: Soil and water. Saprophytic on natural cellulose materials, i.e. various “vegetable debris”, cellophane or bleached corn leaves; US, Maryland (cf., Karling 1949; Sparrow 1960); INDIA , Kerala State and Madras State (Karling 1966); NEW ZEALAND (Karling 1967).

Type: Karling’s illustration (Figs. 70-78; Mycologia 41: p. 516, 1949) of Karlingia marylandica is accepted as the type of Karlingiomyces marylandicus (Karling) Sparrow (1960). Original material isolated from a farm near Frederick , Maryland .

Discussion: Karling (1966, 1967) did not accept Sparrow’s (1960) placement of this species in Karlingiomyces, and continued to recognize it under Karlingia. Karling (1966) first accepted Sparrow’s altered spelling “marilandica”, then (1967) changed it back to the original “marylandica”. According to the ICBN (2000), Article 60.4, the letter “y”, foreign to classical Latin, is permissible in Latin scientific names. Since an original spelling (if not demonstrably incorrect) is to be retained (Article 60.1), there is no cogent reason to alter Karling’s (1949) spelling, except for a termination appropriate to the generic name Karlingiomyces, viz. “marylandicus”.

Dogma (1973) limited Karlingiomyces to only three species: K. asterocystis, K. curvispinosus, and K. dubius. Dogma suggested that Karlingia marylandica (=Karlingiomyces marylandicus) was among certain Karlingia species that, while appearing to be exo-operculate, were actually to be considered as endo-operculate—the operculum being interpreted as slightly sunken in the apex of the discharge papilla or exit tube, as revealed by a slight “collar-like” remnant of the papillar wall remaining above the operculum. However, Karling’s (1949) original description and illustration and Sparrow’s re-description (1960) of Karlingiomyces marylandicus indicate that this species is exo-operculate, although endo-opercula may also form, even in the same exit papilla (Karling 1949) surmounted by an exo-operculum (Fig. 16). Karling (1966) reconfirmed the predominantly exo-operculate character of this taxon.

It is difficult to know whether the lack of resting spores in K. marylandicus is real or merely apparent. A species such as Karlingia rosea (=Rhizophlyctis rosea), though known to occasionally produce resting spores, often does not exhibit these. Sparrow (1973) related this dearth of resting spores to the capacity of ordinary sporangia of K. rosea to form dormant, resistant structures, serving a similar perennating function to resting spores. Only further collecting and culture will demonstrate whether a comparable situation pertains to Karlingiomyces marylandicus.

5. Karlingiomyces exooperculatus (Karling)

Blackwell, Letcher & Powell, comb.nov. FIGURES 18-22

Basionym: Karlingia exooperculata Karling, Nova Hedwigia 28:209, Figs. 1-16, 1977b.

Vegetative: Thallus generally extramatrical on celluose debris, eucarpic, monocentric, or occasionally polycentric. Reproductive: Sporangia developing from the encysted zoospore or from a swelling in germ tube of zoospore, spherical, subspherical, pyriform, ovoid, obpyriform or even reniform, sometimes irregular and somewhat elongate, highly variable in size (15-252 µ m in diameter), hyaline, smooth-walled, the wall somewhat thickened (1.8-2.7 µ m thick). Rhizoidal system: Rhizoidal axes up to 12 µ m in diameter, relatively thin-walled, sometimes containing hyaline and other globules or inclusions, arising at several points on periphery of sporangium, or in some cases from the base of the sporangium, eventually much branched, extending considerable distances (up to 960 µ m). Zoospore discharge: Zoospore discharge papillae 1 or 2, low in relief to long and tube-like, straight, curved or somewhat contorted, 6-240 µ m long, 3-10 µ m broad; exo-operculum conspicuous, 6-12 µ m broad, usually rather strongly convex, often differentially thickened toward the apex; nature of zoospore discharge not reported. Zoospore microscopic: Zoospores spherical, 6-7 µ m; a large hyaline refractive globule apparent, 3.5-4.2 µ m in diameter; flagellum long (48-55 µ m). Resting spore: Spherical, ovoid, oblong, or somewhat elongate, 10-28 µ m in diameter, usually containing a large hyaline refractive globule; wall smooth, golden-brown, thickened (up to 4 µ m), functioning as a prosporangium in germination. Ecology and Distribution: Saprophytic on cellulosic substrates, e.g., may be isolated on cellophane from watered soil cultures; US, Florida ( Orlando ), cf. Karling (1977b).

Type: Karling’s illustration with analysis (Figs. 1-16; Nova Hedwigia 28: pp. 224-225, 1977b) of Karlingia exoperculata (the basionym, cf. Article 33.3, ICBN, 2000) may be accepted as the holotype of the new combination, Karlingiomyces exoperculatus. This illustration was in fact referred to by Karling as the “iconotypus”. Original material of this taxon was isolated from a water culture of soil collected near Orlando , Florida .

Discussion: When Karling (1977b) described Karlingia exooperculata (the description we follow above) he made a point to distinguish K. exooperculata, from certain other “hyaline” species of Karlingia (e.g., K. hyalina), by its conspicuous external operculum. Because of the obvious exo-operculation, and the seemingly correlated feature of a spherical zoospore—containing a single, rather large, refractive globule—we believe that K. exooperculata is more properly placed in Karlingiomyces, than in Karlingia. As regards orthography, Longcore (1996), consistent with the citation in Index of Fungi (Vol. 4, p. 476), hyphenated the epithet (under Karlingia) as exo-operculata. However, Karling (1977b) employed the species epithet without a hyphen (viz.exooperculata); and, since non-hyphenation is generally preferable in scientific epithets (ICBN 2000, Article 60.9), we use the name without the hyphen. The termination (gender) of the epithet is, however, changed herein to –us (i.e., exooperculatus), appropriate to the genus name Karlingiomyces.

   

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