152(151) Gymnothecia red-orange to brick-red. Ascospores orange, subglobose to ellipsoid, with an equatorial furrow, smooth, 4.5-5.5 × 3.5-4.5µm. _Arachniotus ruber_ (fig. 40) - Gymnothecia white or yellow, never orange or brick-red. Ascospores without an equatorial furrow. 153 153(152) Gymnothecia white. Ascospores hyaline, ellipsoid, smooth, 3-4 × 2-2.5µm. _Arachniotus candidus_ - Gymnothecia distinctly pigmented, yellow or brown. Ascospores larger than 4µm. 154 154(153) Gymnothecia yellow brown. Ascospores orange to brownish, slightly lenticular, smooth or slightly roughened, 5-6.5 × 3.3-4.6µm. _Arachniotus confluens_ - Gymnothecia lemon yellow. Ascospores lemon yellow, lenticular, smooth, 5-6 × 3-4.5µm. _Arachniotus citrinus_ [Illustration: FIG. 39. Habit sketch of a gymnothecium and ascus. FIGS 40-45. Spores and peridial hyphae. FIG. 40. _Arachniotus ruber._ FIG. 41. _Myxotrichum chartarum._ FIG. 42. _Gymnoascus californiensis._ FIG. 43. _Gymnoascus reesii._ FIG. 44. _Ctenomyces serratus._ FIG. 45. _Arthroderma curreyi._] 155(151) Gymnothecia possessing only thick pigmented hyphae. 156 - Gymnothecia possessing ± thin, hyaline hyphae with only a few, although often distinctive, appendages (i.e. comb-shaped end cells or dumb-bell shaped asperulate cells accompanying twisted and bent hyphae). 160 156(155) Gymnothecia brown-black or dark greenish-grey, with external hyphae with spine-like branches and septate, hooked appendages. Ascospores orange brownish, ovate, delicately striate, 4-5.2 × 2.4-3.3µm. _Myxotrichum chartarum_ (fig. 41) - Gymnothecia never black, and, if possessing thick-walled hyphae, then appendages never septate. Ascospores smooth, or if ornamented then asperulate or echinulate. 157 157(156) Gymnothecia rose to orange-brown or yellowish. Appendages curved or irregularly branched and pointed, never verticillately branched. Ascospores smooth, or at most asperulate. 158 - Gymnothecia red-brown with appendages verticillately branched. Ascospores 3-4.5 × 2-2.8µm, yellowish brown, lenticular. _Actinodendron verticillatum_ 158(157) Gymnothecia rosy pink when young, becoming browner, with spines and curved, non-septate hairs. Ascospores hyaline, globose to subglobose, asperulate, 3-5 × 2.5-4µm. _Gymnoascus californiensis_ (fig. 42) - Gymnothecia yellow. Ascospores smooth. 159