Ascocarps intraepidermal. In vertical section upper stromatal layer 30-50 µm wide, comprising pale brown to brown, thin to thick walled, more or less globose cells, 4-8 µm diam. Cells becoming paler and thinner walled near outer edge of ascocarp. Periphyses absent. Lower stromatal layer joining the upper, 15-25 µm wide, of 4-5 layers of dark brown, thick walled, more or less globose cells, 5-9 µm diam., the outer layer of cells with darker and thicker walls. Subhymenium 10-20 µm wide, of hyaline, thin walled, rounded cells, 3-8 µm diam. Layer of disorganised hyphal tissue, 20-50 µm wide, between subhymenium and lower wall. Excipulum poorly developed, comprising a few marginal paraphyses becoming closely septate and sometimes capped by dark brown material.

Paraphyses 2-2.2 µm diam., swollen to 4-7 µm diam. at the clavate or fusoid apices, extending 20-30 µm beyond asci. Asci 104-140 x (5-)5.5-7(7.5) µm, cylindric to subclavate, tapering slightly to rounded apex, non-amyloid, 8-spored. Ascus apical thickening and broad pore sometimes seen when immature. Ascospores filiform, 55-78 x 1.2-1.8 µm tapering slightly to basal end, more or less straight when released, 0-1 septate, gelatinous sheath present (see notes below).

Pycnidia depressed-globose, intraepidermal to subepidermal, ostiole not well-defined, often opening through a stomatal cell. Pycnidial wall continuous, not divided into upper and lower parts, 5-12 µm wide, of 1-3 layers of brown, somewhat flattened, pseudoparenchymatous cells, 2-3.5 µm diam. Conidiogenous layer lining whole pycnidium, comprising hyaline, flask-shaped, sympodial conidiogenous cells, 9-18 x 1.5-3.8 µm, with a long, flexuous neck, often with two conidia held at the ends. Conidiogenous cells solitary or borne on poorly developed, irregularly branching conidiophores, intermixed with filiform, sterile elements, especially in area beneath ostiole. The sterile elements may form a column of tissue, almost reaching to the top of the pycnidium. Conidia short-cylindric, rounded ends, 0-septate, hyaline, (3.8-)4.5-6 x 0.8-1(-1.2) µm.

CHARACTERISTICS IN CULTURE: Ascospores of PDD 43034 and PDD 43964 germinated within 5-6 days. Cultures on oatmeal agar 3.5-4 cm diam. after 4 weeks; aerial mycelium sparse, felted, white; agar surface grey toward centre of colony, yellowish toward edge; reverse, yellow. Pycnidia forming near centre of colony, globose, black walled; conidial ooze yellow. Conidiogenous cells and conidia of same appearance and size as those found in nature.

ETYMOLOGY: globosus = globose, spherical; refers to shape of anamorph pycnidium.

NOTES: Some of the collections on Weinmannia racemosa (PDD 44649, 44650, 44653, 44928, 44962) can be separated from typical C. globosus in having asci 7-9 µm wide, and broadly truncate at the apices, and ascospores (71-)80-98 µm long. In all other respects, including the anamorph, they are identical to C. globosus. They have been included here in C. globosus.

The anamorph pycnidium of C. globosus is unusual when compared to those of most other Rhytismataceae, in not being flattened, and in having the conidiogenous layer lining the whole pycnidial cavity. It is similar to that described for Lophodermium camelliicola by Minter & Sharma (1982).

C. globosus is similar in hymenial dimensions to C. phyllocladi. C. phyllocladi differs in that it lacks pycnidia, and has an excipulum which forms from a layer of gelatinised tissue between the hymenium and the outer stromatal layers. Cultural characteristics also differ.

C globosus is also similar to C. antillarum Sherwood and C. spegazzinii Saccardo. From Sherwood's 1980 descriptions, C. antillarum and C. spegazzinii are more or less the same in ascus and ascospore size and shape, and ascocarp margin structure. They appear to differ only in C antillarum lacking zone lines around the lesions, having an excipulum which remains hyaline, and having periphyses lining the upper stromatal wall. The specimens of C antillarum studied (R. Thaxter, 1912-13, on unidentified leaves, Grand Etang, Grenada - holotype FH; Pfister 1006, on unidentified leaves, Grand Etang, Pfister, Carpenter, Sherwood 6.1.1974 - FH) agreed well with the description of Sherwood (1980), but the only specimens of C. spegazzinii examined (Brasil, Apiahy, Puiggari, 1889 - LPS 34990; Venezuela, Edo. Sucre, Dumont et al., 15.VII.1972, NY-VE5083) were small and in poor condition, and did not match the description of the hymenium of C. spegazzinii given by Sherwood. Compared with C. globosus these species have the same macroscopic appearance and hymenial element dimensions, and the excipulum and the way it develops are also similar. C globosus can be separated from C. antillarum in having an anamorph, and in lacking periphyses. C spegazzinii is apparently associated with zone lines, and lacks an anamorph. However, considering the small number of collections of C. antillarum and C. spegazzinii in herbaria and the relatively minor differences between all three taxa, they may in fact be found to be conspecific when more South American collections are available for comparison.