Scientific explanations include that exposure to light, lack of moisture or absence of food can cause sporangia to form from the plasmodium. At least one of these three conditions has been present every time I've seen sporangia form.
Source: wiktionary
Asexual reproduction by the production of a bud in place of a sporangium is not uncommon.
Source: wiktionary
The sporangia, however, are much larger: 3–4 mm long 0.7–1.1 mm in diameter versus only 1–1.5 mm long 0.5–0.8 mm in Corynepteris, and are characteristically banana shaped with a pair of elongate annuli.
Source: wiktionary