Candelina submexicana
Candelina submexicana is a species of saxicolous crustose lichen in the family Candelariaceae. This small lichen forms yellow patches that hug tightly to rock surfaces, with flattened radiating outward from the center. It is closely related to Candelina mexicana but can be distinguished by its smaller size, more reddish-yellow color, and different internal structure. The species grows in sunny, dry locations across Mexico, the southwestern United States, and Peru, typically on exposed non-limestone rocks.
Taxonomy
Candelina submexicana was originally described by Maurice Bouly de Lesdain as Placodium submexicanum. Poelt transferred it to Candelina and, because Bouly de Lesdain's herbarium had been destroyed, designated a new type: Frère Nicolas no. 5647 from "Tepoxúchitl", Puebla, noting that this superseded his provisional typification from 1958. Poelt also listed a second syntype locality at Río San Francisco, Puebla, and documented later combinations the name passed through.Description
The species forms small, closely appressed rosettes. Compared with Candelina mexicana, Poelt noted that the thallus is usually much smaller; marginal lobes are up to about 2 mm long and 0.2–0.5 mm wide, strongly flattened and tightly attached; the surface often has a more reddish-yellow cast and reacts K+ in spot tests. The medulla is entirely white and lacks the yellow needles seen in C. mexicana. Apothecia are about 0.3–0.5 mm across, rather narrowly attached, with flat and to notched margins. The ascospores are narrowly ellipsoid, and measure 11–15 × 3.3–4.5 μm.The cortex conforms to the Candelina type: a thin layer capped by a dense, closely cemented band of yellow pigment, lacking the "peppered pigment hoods" and flaking hyaline coating that characterise Placomaronea; the medulla is white rather than hollow. Thin-layer chromatography shows pulvinic acid derivatives with several chemotypes; most tested specimens of C. submexicana react K+ on the thallus, consistent with pulvinic series compounds detected on TLC.