[Notes from Kew Type specimen, PRJ 2010] Kew images.

Specimens examined.-(1) J. H. Wareup (Type, Waite Institute 15645), isolated from soil collected by K. F. Baker near Rotorua, New Zealand, 1961. (2) P. C. Misra, PCM 530, isolated from sal forest soil, Gorakhpur, U.P., India, 1962.

Colonies on neutral Czapek-Dox yeast agar bright yellow, later velvety and greyish-olive, with yellow pigment produced in the medium. Phialophores arising from yellowish repent hyphae, unbranched or sparsely branched, hyaline to pale straw-colored, smooth, with frequent septa, up to about 1 mm in length and 5.5 - 7.5 - (9) µ wide, the branches terminating in small fascicles of 1 - 3 - (5) phialides each bearing a persistent chain of phialospores formed in basipetal succession. Phialides hyaline, subcylindrical to bottle-shaped with often a median constriction, narrowed towards the base, abruptly attenuated into a short and relatively wide neck at the apex, usually monoverticillate but sometimes biverticillate, 20 - 30 - (38) x 6.5 - 8.5 - (10) µ, (2.5) - 3 - 4 µ wide at the mouth. The first-formed phialide is terminal; the next-formed arises as a branch of the phialophore just below the basal septum of the first phialide and is then cut off by a septum. Subsequent phialides develop in the same way. Phialospores are extruded in basipetal succession from the phialides and form persistent chains of as many as 26 phialospores that do not slime down. The phialospores, when first forming, are hyaline with a vague roughening of the wall, soon becoming deep yellow-brown and covered with irregular, shallow, dark-brown warts. The phialospores are mostly fusiform-ellipsoid and prominently biapiculate from the remains of connectives which join them in the chain, (16) - 20 - 26- (30) x (12) -16 - 20 - (27) µ; some are subspherical 15 - 26 µ diam.

Coloniae in agaro neutrali Czapek-Dox cum fermento lucide luteae, postea vero velutinae et griseo-olivaceae, pigmento luteo producto ad medium. Phialophora emergentia e hyphis repentibus luteolis, haud ramosa vel sparse ramosa, hyalina vel pallide straminea, levia, septis frequentibus, ad ca 1 mm longa, et 5.5 - 7.5 - (9) µ lata, ramis desinentibus in fasciculos parvos constantes ex 1 - 3 - (5) phialidibus, quarum singulae supportant catenam perstantem phialosporarum. Phialides hyalinae, subcylindricae, vel urceolatae, saepe semel constrictae ad medium, angustatae ad basin, abrupte fastigatae in collum breve et sat latum ad apicem, vulgo monoverticillatae, nonnumquain biverticillatae, 20 - 30 - (38) x 6.5 - 8.5 - (10) µ, (2.5) - 3 - 4 µ latae ad os. Phialides primo efformatae terminales, subsequentes vero efformantur ut rami phialophororum sub ipsum septum basale phialidis primae, et tunc septis propriis separantur. Phialosporae alte luteo-brunneae, opertae verrucis fusce brunneis et tenuibus, vulgo fusiformes-ellipsoideae et eminenter biapiculatae ex reliquiis connectivi conjungentis singulas inter se in catena, (16) - 20 - 26 - (30) x (12) - 16 - 20 - (27) µ, nonnumquam subsphaericae 15 - 26 µ diam., emergentes successione basipetali ex phialidibus et efformantes catenas perstantes constantesque e phialosporis numero ad 26, quae non dilabuntur.
Lectus in solo thermali prope Rotorua in Nova Zelandia, typus Waite Instit. 15645; lectus quoque in solo in silva Shoreae ad Gorakhpur in India.

These two specimens were referred almost simultaneously to Dr. S. J. Hughes, who kindly put the authors in communication with each other. The genus Paecilomyces (Brown and Smith 1957) is largely characterized by its whorls of divergent phialides which have a subcylindrical body narrowed towards the base but tapering gradually or abruptly at the apex into a slender tube nearly as long as the phialide body and usually bent away from its main axis. The phialospores in Paecilomyces are hyaline under the microscope, mostly smooth but in some species slightly rugose, ovate, elongate, subcylindrical or rarely subspherical ; phialospores 8-10 µ long are considered large in this genus. In Phialomyces, on the other hand, the phialides have a short neck and the phialospores are considerably larger, dark, coarsely warted, and biapiculate.
The dark phialospores and small, usually monoverticillate whorls of phialides found in Phialomyces are reminiscent of those found in Memnoniella and Stachybotrys (Galloway 1933; Bisby 1943, 1945; Zuck 1946; Bisby and Ellis 1949). However, the phialides are again a distinguishing feature, for those in Memnoniella and Stachybotrys have no apical neck or at most only a small mammillate projection.
Phialomyces macrosporus was first isolated from thermal soils but has not proved to be markedly thermophilic in culture.
Subcultures of the type culture have been deposited with the Commonwealth Mycological Institute, Kew, the Centraalbureau voor Schimmelcultures, Baarn, and in Herb. D.A.O.M., Ottawa.