Otatea ximenae (Fig. 14)

Material examined: — MEXICO. Oaxaca: Asunción Nochixtlán, Km 190 of the Puebla-Oaxaca highway, 17°23’9.1”N, 97°8’8.9”W 1928 m, 2 February 2020, Ruiz-Sanchez & M . A . García-Martínez 645 (IBUG!) .

Culm anatomy description: —Culm solid. Epidermis with a layer of axially elongated lignified cells, 12 µm length, with occasional rectangular silica bodies on top (Fig. 16C). Cortex with one layer of thick-walled cells followed by 2 layers of wider, thinner-walled ovoidal cells (3 layers in total, 30 µm length; Fig. 16C). Vascular bundles in 5–6 alternating cycles (Fig. 16A). Peripheral, transitional, and central vascular bundles surrounded by a sclerenchyma sheath defining their contour (Figs. 16D–F). Ovate central vascular bundles, 309 ×304 μm; two round shaped metaxylem vessels, 75 × 83 μm; phloem with sieve tubes and companion cells located between two metaxylem vessels on the upper level, 78 × 98 µm; sieve tubes 19 × 20 µm (Fig. 16F). Ground parenchyma with abundant starch grains. Frequent conical silica bodies across the ground tissue occupying intercellular spaces covering a mean area of 10 µm 2 (Fig. 16B).