Endoparasites of soil nematodes and rotifers II: The genus Haptocillium

Mycologist, Volume 19, Part 1 February 2005. ©Cambridge University Press Printed in the United Kingdom. DOI: 10.1017/S0269915XO5001011

Endoparasites of soil nematodes and rotifers II: The genus Haptocillium S. L. GLOCKLING1 & G. P. HOLBROOK Department of Biological Sciences, Northern Illinois University, DeKalb. IL 60115, USA. 1 Present address: Maypole House, 39 Church St, Gamlingay, Nr. Sandy, Bedfordshire, UK, SG19 3JJ.

Two species of nematode endoparasites, Acrostalagmus bactrosporus Drechsler and Acrostalagmus obovatus Drechsler, which infect by spore adhesion, are transferred into the recently erected genus, Haptocillium Zare and Gams. We report on these species for the first time since their initial description over 60 years ago. Cultivation of both these fungi on corn meal agar revealed the production of alternative spore types not seen in association with the nematode host.

Introduction The genus Haptocillium Zare & Gams was recently erected following molecular analysis of seven species of nematode parasites which infect by means of adhesive conidia (Zare & Gams, 2001). This genus of nematophagous fungi has quite a chequered history, with species having been described in several genera (Acrostalagmus, Acremonium, Verticillium, Spicarea, Tolypocladium and Cephalosporium). A few taxa have been synonymised, some re-established and many reclassified several times. In general, Haptocillium comprises the Verticillium-like nematode parasites which often bear conidia on elongate conidiogenous cells that grow in a whorled arrangement around the conidiophore. However, some species have flaskedshaped or saccate conidiogenous cells which may lack the whorled arrangement, particularly when growing from the nematode host. The type species of Haptocillium, H. balanoides (Drechsler) Zare & Gams, has balanoid (acorn-shaped) conidia which are thickened at the broader distal end (the acorn cup) where they adhere to the host to initiate a new infection. This species has probably been reclassified more than any other in this group. Initially described as Cephalosporium balanoides (Drechsler, 1941), it was put into Acremonium (Subramanian, 1979), before being re-examined morphologically and allocated to Verticillium (Dowset et al., 1982). Bisset (1983) removed it to Tolypocladium but Gams (1988) reinstated it as Verticillium balanoides, whilst synonymising several other species under the same binomial in a broad species concept (Gams, 1988). 2

Glockling & Dick (1997) disagreed with this broad concept and re-instated one synonymised species as Verticillium zeosporum (Drechsler) Glockling, whilst describing two new species, V. campanulatum Glockling and V. seriatum Glockling. Recent sequencing of ITS regions and the 5.8S gene has now strengthened the individuality of some species in this group and Zare and Gams subsequently erected the genus Haptocillium (Zare and Gams, 2001). Although only seven species of Haptocillium were sequenced and included in a key by these authors, they acknowledged the probable validity of several other species, of which cultures were not available. In this paper we assign a further two species to Haptocillium which are previously known only from their initial descriptions over 60 years ago as Acrostalagmus bactrosporus Drechsler and Acrostalagmus obovatus Drechsler (Drechsler, 1941). We report on the morphology of these species in association with the nematode host and also growing on corn meal agar (CMA) in pure culture. We illustrate these species with the first photo micrographs and review them in context with other members of the genus. Methods Preparation of cultures and isolation of fungi A collection of white tailed deer dung from Kingston, Illinois, USA was mixed with distilled water in a plastic bag and the faecal pellets were crushed until a slurry was obtained. A few drops were placed on three Petri dishes of corn meal agar (CMA) and additional water was added once the slurry had dried to the surface.

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Plates were regularly inspected using the 10x objective of the light microscope and infected nematodes were removed for photography and cultivation. Specimens on slides were observed using a Nikon E600 microscope equipped with phase contrast and DIC optics, and photographed with a digital still camera (Nikon DXM1200). To obtain pure cultures, infected nematodes were washed with sterile water and mounted in a hanging drop slide culture in Grace’s medium with added antibiotics (as described in Glockling & Shimazu, 1997). Once growth was visible to the naked eye, the fungi were picked up with a sterile glass needle and transferred to Petri dishes of CMA. For SEM, some fresh fungal growth from pure cultures was mounted onto stubs and gold sputter-coated before observing under low vacuum using a Jeol JSM 5610LV SEM. Results and Observations The two species illustrated here, Haptocillium bactrosporum and H. obovatum, were isolated from nematodes from the same collection of white tailed deer dung taken from Kingston Park in Illinois, USA, in the summer of 2002. The nematodes which succumbed to infection were bactiverous and resembled Plectus, but we were unable to identify them critically. Charles Drechsler isolated Acrostalagmus bactrosporus from the bactiverous nematode, Plectus parvus, in samples of leaf litter from Maryland and Virginia, USA, in 1941 (Drechsler, 1941). This species was later transferred to the genus Verticillium (Subramanian, 1977). The isolate examined here compares well to the original description of A. bactrosporus growing from the nematode host as given by Drechsler (1941). Glockling (1998) reported a rotifer parasite isolated in Japan, as being morphologically similar to A. bactrosporus. Glockling subsequently isolated another species with bacilliform conidia from nematodes in the UK, provisionally identified as A. bactrosporus (Glockling, unpublished). However, critical examination of cultures and molecular sequencing of both these isolates showed them to be new species distinct from A. bactrosporus, and they were consequently described as Pochonia microbactrospora Gams & Zare (Zare et al., 2001) and Haptocillium rhabdosporum Zare & Gams respectively (Zare & Gams, 2001). Thus, no isolate morphologically identical to that of Drechsler’s has been isolated until now, and this has given us a chance to review this fungus in its parasitic state and also, for the first time, in artificial culture. Culturing of these organisms is often interesting and surprising because, as with some other

genera of nematophagous parasites, alternative spore forms may be produced. Haptocillium bactrosporum (Drechsler) S. L. Glockling comb. nov. = Acrostalagmus bactrosporus Drechsler C. Phytopathology 31: 782 (1941). = Verticillium bactrosporum (Drechsler) Subramanian, Kavaka 5: 98 (1977). Colonies, on CMA, slow growing, reaching 5 mm diam. in 10 days. Upper side white with cream perimeter, under side creamy yellow. Vegetative hyphae 1.5-3.0 µm diam.; some chains of thick-walled intercalary cells 7-15 µm long x 3.0-5.0 µm. Aerial conidiophores, up to 500 µm long x 3.0-4.0 µm diam., with whorls of elongate, tapered conidiogenous cells 12-15 µm long, 2.5-4.0 µm diam. at the swollen base, tapering gently to a long slender neck, 1.0µm diam. Conidiogenous cells producing successive bacilliform conidia 3.0 µm long x 2.0 µm wide (some larger conidia 5.0 x 2.5 µm in older cultures), truncate or slightly rounded at the ends, adhering in a bundle at the conidiogenous cell tip. Spherical conidiogenous cells 5.0 µm diam., produced near the agar surface, sessile on the hyphae or borne on short hyphal branches, easily detaching, becoming polysterigmatic, producing either ovoid or bacilliform conidia on one to several narrow sterigmata, 0.5-1.0 µm diam, sterigmata sometimes branched. Ovoid conidia 4.0 x 2.5-3.0 µm, borne mostly on elongate tapering conidiogenous cells in older cultures and clustering at the conidiogenous cell tips. Conidiogenous cells producing ovoid conidia 10-15 µm x 3-4 µm at base, 1.0 µm diam. at apex, often polysterigamatic. Ovoid conidia common but not as abundant as bacilliform conidia. Infection of nematodes in H. bactrosporum was by adhesion of bacilliform conidia. In association with the nematode host, long conidiophores grew erect to a height of 300 µm (Figs 1,5). Assimilative hyphae packed the nematode body (Fig 6) and a vase-shaped cell formed at the base of the protruding conidiophore (Fig 3, *). Sometimes there was a collar at the conidiophore base just above this swollen cell (Fig 3, arrows) but this feature was not always present. Elongate conidiogenous cells (Figs 4, 7) were often arranged in whorls at regular intervals around the conidiophore (Fig 2). Sometimes conidiogenous cells were gently tapered from base to apex (Fig 4) but others had a vase-shaped base and a long narrow apex (Fig. 7). Bacilliform conidia were successively produced (Figs 2,7) and adhered in small clumps at the apices of the 3

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conidiogenous cells (Fig 1, arrows). The morphological details of the fungus tallied well with the original description (Drechsler, 1941). Initial inspection of H. bactrosporum growing in pure culture on CMA revealed aerial sporulation by tapered conidiogenous cells, arranged in whorls around the conidiophore, producing typical bacilliform infection conidia (Fig 8). These conidia adhered to the tip of the conidiogenous cell in small bundles (Fig 21). There were also some chains of thick-walled septate cells growing below the agar surface (Fig 9). Inspection of slightly older cultures revealed a second conidial form which was broad ovoid (Fig 10). It was not immediately obvious where these ovoid cells were being produced as conidia dispersed easily on water slide preparations. Further inspection revealed spherical bodies, presumably equivalent to conidiogenous cells (Fig 13), producing one to several sterigmata on which the ovoid conidia were formed (Fig 12). These spherical conidiogenous cells were mostly detached on slide preparations but critical examination showed that they were borne either on short, broad hyphae from the main hyphal filaments (Fig 16), or more usually, were sessile on the hyphae (Figs 15,17), often associated with the chains of thick walled cells (Fig 13). The hyphae on which the spherical conidiogenous cells were borne grew near the agar surface, unlike the conidiophores producing bacilliform conidia, which were always aerial (Fig 8). The spherical conidiogenous cells appeared to detach from the hyphae very readily after being wetted. Both the spherical conidiogenous cells and the broad ovoid conidia appeared refractive under phase contrast optics (Figs 10, 12, 13). Spherical conidiogenous cells also sometimes produced bacilliform conidia (Fig 14). In older cultures, detached spherical conidiogenous cells were much less common, although ovoid conidia were still abundantly present, although not as numerous as the bacilliform infection conidia. The mode of production of the ovoid conidia appeared to change with repeated sub-culturing and also with age. In these older cultures, ovoid conidia were seen to be produced on elongate or flask-shaped

conidiogenous cells (Fig 11) similar to those producing the bacilliform conidia. Some conidiophores bore whorls of conidiogenous cells which produced only ovoid conidia (Fig 19). These massed in a ball at the conidiogenous cell apex in the same manner as the bacilliform conidia. Conidiogenous cells bearing ovoid conidia in older cultures often had two sterigmata (Fig 18). We did not observe germination of the ovoid conidia or of the bacilliform conidia. In older cultures, conidial size and shape exhibited a much wider variation (Fig 20). The second species illustrated here, Haptocillium obovatum, needs to be redescribed as a species of Haptocillium as it was recently synonymised in H. sphaerosporum (Goodey) Zare & Gams (2001). Our isolation and cultivation of H. obovatum, again the first since its discovery in 1940, has rendered much new morphological data about this species which clearly distinguishes it from other Haptocillium species, including H. sphaerosporum. Haptocillium obovatum (Drech.) S. L. Glockling comb. nov. = Acrostalagmus obovatus Drechsler, C. Phytopathology 31: 784 (1941). = Verticillium obovatum (Drech.) Subramanian, Kavaka 5: 98 (1978) non Haptocillium sphaericum (J.B. Goodey) Zare & Gams Nova Hedwigia 73: (2001). In pure culture on CMA, colonies slow growing, reaching 4-6 mm in 10 days. Upper side white and fluffy, under side pale creamy yellow with white perimeter. Vegetative hyphae 1.5-3.5 µm diam., with some long chains of short, bulbous cells in older cultures, 5.0-20.0 µm long x 7.0-15 µm diam. Aerial conidiophores up to 500 µm long x 2-4 µm diam, bearing saccate or flask-shaped conidiogenous cells, 7.0-9.0 µm long, 2.0-3.5 µm diam at the swollen base, with a short narrow apex, 0.5-1.0 µm diam. Conidiogenous cells producing either obovoid infection conidia, 3.0-3.5 x 2.0-2.5 µm or broad cylindrical

Figs 1-21 H. bactrosporum. Fig 1 Aerial conidiophores growing from the nematode host in a preparation from deer dung, producing balls of conidia at the conidiogenous cell apices (arrows). Fig 2 Whorled conidiogenous cells on conidiophores growing from host. Fig 3 Base of conidiophores with collar (arrows) over swollen cell (*) which penetrates the nematode cuticle. Fig 4 Elongate tapered conidiogenous cell producing a conidium. Fig 5 Nematode with internal vegetative hyphae and external conidiophores. Fig 6 Nematode body filled with vegetative hyphae. Fig 7 Elongate conidiogenous cells with swollen base and long slender apices from the host. Fig 8 Whorled conidiogenous cells producing bacilliform conidia from culture. Fig 9 Chains of thick-walled cells in culture. Fig 10 Bacciliform and broad ovoid conidia from pure culture. Fig 11 Ovoid conidia produced from elongate conidiogenous cells in older pure culture. Fig 12 Detached spherical cell with three sterigmata bearing ovoid conidia. Fig 13 Spherical cells, one attached to the hypha (arrow). Fig 14 Non germinated spherical cell and polysterigmatic spherical cell (*) with one branched sterigma (arrow), producing bacilliform conidia. Fig 15 Sessile spherical cell attached to a hypha (DIC). Fig 16 Spherical cell on a short hyphal branch. Fig 17 Sessile spherical cell attached to hypha

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(arrow) (phase contrast). Fig 18 Conidiogenous cell with two sterigmata (arrow) producing ovoid conidia in older culture. Fig 19 Ovoid conidia borne on elongate conidiogenous cells in older culture. Fig 20 Conidia in older culture showing variation in conidial size. Fig 21 Low vacuum SEM of bacilliform conidia massed at the conidiogenous cell apex in pure culture.

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conidia with rounded ends, 10.0-15.0 µm x 3.0-4.0 µm. Both types of conidia borne on the same conidiophore, but not from the same conidiogenous cell. Cylindrical conidia often borne apically on the conidiophore, but also produced from flask-shaped or saccate conidiogenous cells further down the conidiophore. Germination of dispersed cylindrical conidia occurring readily, producing obovoid conidia (morphologically identical to infection conidia) on one terminal sterigma, 2.5-3.0 µm x 1.0-1.5 µm wide, occasionally on two sterigmata, one at each end of the cylindrical spore. Cylindrical conidia occasionally forming ovoid conidia directly. Cylindrical conidia considerably fewer than obovoid conidia, becoming less common in older cultures. Cylindrical conidia sometimes germinating with narrow germination hypha, 1.0 µm diam. Ovoid conidia germinating, forming spherical hypha, 2.0-3.0 µm diam and a narrow distal germination hypha, 0.5-1.0 µm diam. Infection of nematodes in H. obovatum was via obovoid conidia which adhered to the nematode cuticle by the broad distal end (Fig 27). Growing from the nematode host (Fig 23), this isolate was identical to that described by Drechsler (1941). Assimilative septate hyphae packed the nematode body (Fig 24) prior to sporulation. Small obovoid conidia, 2.5-3.0 µm long x 2.0 µm wide, were produced from flask-shaped or saccate conidiogenous cells (Figs 24, 25). Conidiogenous cells were arranged irregularly on the conidiophore, singly or in bunches. Conidia were successively produced and remained in large bundles at the conidiogenous cell apex (Fig 22, arrows) until dispersal. The infection conidia did not appear discernably thickened at the distal end (Figs 25, 37). Growing from the nematode host, H. obovatum differs from most other species of Haptocillium because the conidiogenous cells are saccate or flask-shaped and are not borne in the usual whorled arrangement at regular intervals along the conidiophore. Instead, they tend to be single or bunched along short conidiophores, and often proliferating (Figs 24, 25). In pure culture on CMA, regular obovoid infection conidia were produced (Fig 26), still by saccate conidiogenous cells which were often borne singly along the conidiophores (Fig 28). Chains of thickened hyphal cells were present amongst the vegetative hyphae growing through the agar, and these cells were usually short and bulbous (Fig 32). Again, as with several other Haptocillium species, an alternative spore form was found to be produced in pure culture (Fig 29, arrow). This second spore type was broad cylindrical with rounded ends, much larger than the infection 6

spores, measuring 12-15 µm long x 3-4 µm wide (Figs 29, 30). In this case, the cylindrical spores were produced on the same conidiophores as those producing obovoid conidia (Fig 28), and were often borne apically on the tapered distal end of the conidiophores (Fig 30). However, they were also produced by flask-shaped conidiogenous cells lower down the conidiophore. The alternative cylindrical spore germinated readily, producing an obovoid conidium, usually on a single sterigma at one end (Fig 31). Occasionally two sterigmata formed, one on each end. Sometimes the sterigmata were absent and the obovoid conidia were produced directly (Fig 34). The obovoid conidia produced from the cylindrical conidia (Figs 31, 34) appeared morphologically identical to the infection conidia produced from saccate conidiogenous cells (Figs 26, 36). In older sub-cultures, cylindrical spores were seen to have germinated to produce a narrow hypha at each end (Fig 33). Older cultures also revealed obovoid conidia commonly produced on proliferating conidiogenous cells (Fig 36). Obovoid conidia also germinated in older cultures (Fig 35, *), initially producing a spherical hypha (Fig 35, arrow) from which a narrow hypha grew (Fig 35). Discussion Haptocillium is known to infect several nematode species, and yet, with records to date, each Haptocillium species appears to have a limited degree of host specificity. H. bactrosporum, H. obovatum and H balanoides have all been recorded from Plectus parvus with the latter also infecting Acrobeloides butschii (Drechsler, 1941). H. glocklingiae and V. seriatum infected Plectus parietinus nematodes (Glockling, 1994; Glockling & Dick, 1997). H. zeosporum was isolated from Panagrolaimus (Drechsler, 1945; Glockling, 1994) as was H. campanulatum (Glockling & Dick, 1997). H. sinense was described from Meloidogyne nematodes (Zhang, Cao and Liang, 1996). H. sphaerosporum was isolated from the stem nematode, Ditylenchus (Goodey, 1951), whilst Watanabe’s variety, V. sphaerosporum var bispora, infected Aphelenchoides, Cephalobus and Panagrolaimus (Watanabe, 1980). Acrostalagmus gonoides Drechsler was recorded from Bunonema nematodes (Drechsler, 1942). Other nonnematophagous isolates were attributed to this taxon and were transferred to the genus Pochonia as P. gonoides following examination (Zare et al, 2001). We would question the conspecificity of these isolates with A. gonoides, as they have no association with nematodes and have isodiametric conidia. A. gonoides is probably a host-dependent and host-specific species attributable to

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Haptocillium. Unfortunately no comprehensive study combining the expertise of taxonomists in mycology and nematology has yet been carried out to ascertain the degree of host specificity within this group of nematode endoparasites. Although we have extended the descriptions of H. bactrosporum and H. obovatum by describing their morphology from pure culture as Zare & Gams (2001) have done for several other species, we wish to stress the importance of observing these species in their natural association with their nematode hosts. This is because, whilst reproducing from a nematode, each species has a well defined morphology which separates them from one another. Although the presence of alternative conidia in pure culture can be of use in identification, other indicators of taxonomic importance, such as the size and shape of conidia and conidiogenous cells and whether conidia are massed in a ball or produced in a catenulate manner, become much more varied and less well defined (Dowsett et al., 1982; Gams, 1988; Glockling & Dick, 1997; Zare & Gams, 2001). In general, in axenic culture, the small distinguishing balanoid, obovoid, spherical, conical or campaniform infection conidia all begin to appear rather similar and balanoid. Zare & Gams (2001) also noted that different shapes of conidiogenous cell are produced on different types of agar. Because of these variations, identification from pure culture is much less reliable than that from the natural fungal/host association. The variability in conidiogenous cell shape in Haptocillium is well demonstrated here from the long elegant tapered conidiogenous cell in H. bactrosporum to the short, fat, saccate conidiogenous cells of H. obovatum. A few other Haptocillium species also have saccate conidiogenous cells. These include H. glocklingiae, which has conical conidia, H. balanoides, the type species with balanoid conidia and H. sphaerosporum which has spherical to ovoid conidia. The spherical and detachable polysterigmatic conidiogenous cells found here in H. bactrosporum are highly unusual and we find no comparison in other members of this nematophagous group. Indeed, we are not certain whether they should be referred to as conidiogenous cells or conidia. When we first observed them as detached cells in the slide preparations we

considered the possibility of them being a contaminant. But in later preparations we discovered some attached to hyphae, and their production of ovoid and bacilliform conidia supported their being an integral but transitory product of artificial cultivation of H. bactrosporum. It is not uncommon for fungal endoparasites of nematodes to produce an alternative conidial form. Some have more than one spore type produced when in association with the nematode host, whilst others only produce alternative spores when cultivated artificially. Production of alternative spore types has previously been found to occur in species of Haptocillium and also in Harposporium. The purpose of these alternative conidia, assuming they have one, is still rather obscure although there has been some indication in a Harposporium species that they may infect an alternative insect host (Shimazu & Glockling, 1998). However, in many species it may just be an aid to dispersal and propagation, especially as in both the Haptocillium species described here, we find conidia that are morphologically identical to infection conidia being produced from dispersed, germinated alternative conidial or conidiogenous cell types. The alternative spore types may be longer lived than the infection conidia. In some Harposporium species, thick-walled chlamydospores are produced inside the host, and other species form aerial arthrospores from the host. Some species such as H. zeospoum, H. sphaerosporum and A. gonoides form bulbous chlamydospores, known as dictyochlamydospores, when growing from the nematode host. Thick-walled cellular hyphae comparable to those found in both species described here, were also noted in cultures of H. balanoides (Dowsett et al., 1982). These authors considered whether these cells might represent an intercalary chalamydospore (Dowsett et al., 1982). Alternative spore forms in some species are only produced in pure culture although Haptocillium campanulatum (Glockling) Zare & Gams is unusual in its production of two conidial types from the same conidiophore growing from the nematode host (Glockling & Dick, 1987). H. campanulatum has a second spore form which differs in being broadly ovoid and larger than the infective bell-shaped conidia

Figs 22-37 H. obovatum Fig 22 Bundles of conidia borne on aerial conidiophores above the nematode host (arrows). Fig 23 Short conidiophores growing out from nematode. Fig 24 Head end of infected nematode filled with septate assimilative hyphae with sporulation occurring externally and some proliferating conidiogenous cells (arrows). (DIC). Fig 25 Saccate conidiogenous cells protrding through the host cuticle (arrows) and producing obovoid conidia. Fig 26 Obovoid conidia from pure culture. Fig 27 Conidia adhering by the distal end to the mouth of a live nematode. Fig 28 Aerial sporulation in pure culture producing both conidial types from the same conidiophores. Fig 29 Large cylindrical conidium (arrows) and small obovoid conidia in culture. Fig 30 Cylindrical conidium at conidiophore apex and obovoid conidium on saccate conidiogenous cell lower down the same conidiophore. Fig 31 Germinated cylindrical conidium having produced an obovoid conidium on a

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short sterigma. Fig 32 Short, broad, chains of cells in older culture. Fig 33 Germinated cylindrical conidium forming a narrow hypha. Fig 34 Direct germination of cylindrical conidium to form obovoid conidia. Fig 35 Germination of obovoid conidium (*) to form a spherical hypha (arrow) and a narrow, branched, germination hypha. Fig 36 Proliferating conidiogenous cell in older culture producing obovoid conidia. Fig 37 Low vacuum SEM of obovoid conidia in culture.

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(Glockling & Dick, 1987). This alternative ovoid conidium is the closest comparison to the ovoid conidia we found in pure cultures of H. bactrosporum. The cylindrical conidia found in pure cultures of H. obovatum are comparable to those of some other Haptocillium species. In H. glocklingiae, which has conical infection conidia, the alternative cylindrical spore is shorter, measuring 5.7-6.5 x 2.0-2.2µm. In H. balanoides and H. sphaerosporm, cylindrical conidia are 5.0-7.5 x 1.5-2.0 µm and 6.0-7.5 x 2.2-2.5 µm respectively. Watanabe (1980) described Verticillium sphaerosporum var. bispora, which he deemed similar to Goodey’s species, but found it produced large cylindrical spores in culture, measuring 5-13 x 2.0-2.8 µm. Thus these alternative spores fall within the range described here for H. obovatum. However, V. sphaerosporum var. bispora clearly has almost spherical infection conidia which are borne on elongate conidiogenous cells that are often in a whorled arrangement on the conidiophore (Watanabe, 1980). Zare and Gams (2001) tentatively synonymised Watanabe’s variety with H. balanoides, but we accept it here as valid based on the different size and shape of the infection conidia and the much larger cylindrical spores. Despite being a small genus, Haptocillium accommodates morphologically diverse nematode parasites which are still very little known and not well understood. We hope that this account has helped to increase our knowledge of this group of which only nominal accounts are available. Acknowledgements SLG wishes to thank NSF (Grant # DEB0213076) for light microsopy equipment and the Department of Biololgical Sciences, NIU for funding. We thank Bob Bailey, Department of Geology, NIU for SEM facilities.

References Bisset, J. (1982) Notes on Tolypocladium and related genera. Canadian Journal of Botany 61: 1311-1329. Dowsett, J. A., Reid, J. & Hopkins, A. (1982) On Cephalosporium balanoides Drechsler. Mycologia 74: 687690. Drechsler, C. (1941) Some hyphomycetes parasitic on free-living terricolous nematodes. Phytopathology 31: 773-801. Drechsler, C. (1942) Two zoophagous species of Acrostalagmus with multicellular Desmidiospora-like chlamydospores. Journal of the Washington Academy of Sciences 32: 343-350. Drechsler, C. (1946) A new hyphomycete parasitic on a species of nematode. Phytopathology 36: 213-217. Gams, W. (1988) A contribution to the knowledge of nematophagous species of Verticillium. Netherlands Journal of Plant Pathology 94: 123-148. Glockling, S. L. & Dick, M. W. (1997) Two new species of nematophagous Verticillium (Hyphomycetes) forming catenulate conidia, with a key to the nematophagous Verticillium species. Nordic Journal of Botany 17: 653-662. Glockling, S. L. & Shimazu, M. (1997) Culturing of three species of endoparasitic fungi infecting nematodes. Mycological Research 101: 55-60. Glockling, S. L. (1994) Predacious and parasitoidal fungi in association with herbivore dung in deciduous woodlands. PhD thesis, University of Reading, UK. Glockling, S. L. (1998) Two new species of rotifer-attacking fungi, Rotiferophthora, from Japan and records of Verticillium bactrosporum in rotifer hosts. Mycological Research 102: 145-150. Goodey, J. B. (1951). A new species of hyphomycete attacking the stem eelworm Ditylenchus dipsaci. Transactions of the British Mycological Society 34: 270-272. Watanabe, T. (1980) A new variety of Verticillium sphaerosporum, an endoparasite of nematodes and its antagonism to soil borne plant pathogens. Annals of the Phytopathology Society of Japan 46: 598-606. Zare, R. & Gams, W. (2001) A revision of Verticillium section Prostrata. VI. The genus Haptocillium. Nova Hedwigia 73: 271-292. Zare, R., Gams, W. and Evans, H. C. (2001) A revision of Verticillium section Prostrata. V. The genus Pochonia, with notes on Rotiferophthora. Nova Hedwigia 73: 51-86. Zhang, K-Q, Cao, L. and Liang, Z-Q. (1996) A new nematophagous species of Verticillium from China. Mycological Research 100: 1481-1482.

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