Myriopteris maxoniana

While the only specimen known lacks a rhizome, it is believed, from examination of the leaf base, to bear linear to lanceolate, orange-tan scales. The fronds are 28 to 40 centimeters (11 to 16 in) long. The stipe (the stalk of the leaf, below the leaf blade) takes up from 40% to 50% of the length of the frond. It is purplish-black in color and round, bearing abundant orange-tan hairs tipped with glands. These are of two different lengths, some 0.1–0.3 mm and others 1–1.5 mm. The leaf blades are narrow and slightly widened towards the tip, and tripinnate (cut to pinnae, pinnules, and pinnulets) in the most divided leaves. The pinnae are roughly opposite each other and more or less symmetric about the costa (pinna axis). Their segments are broadly fused. Both surfaces of the pinnae are covered with scattered straight, orange-tan spreading hairs 2 mm in length; unlike the hairs of the stipe, they lack glands. The sporangia occur at the tips of the veins, with 1 to 3 typically covered by the folded edge of a segment lobe. The edges of the leaf are not noticeably differentiated from the bulk of the leaf tissue where they fold over the sporangia. The spores in the sporangia are dark brown in color. Myriopteris maxoniana closely resembles Myriopteris longipila. …

Myriopteris maxoniana is only known from a single specimen, collected by Leslie Viereck in San Lucas, Tamaulipas, Mexico. Its habitat is not recorded.