Otatea, García-Martínez & Terrazas & Sánchez & Reyes & Ruiz-Sanchez, 2023

García-Martínez, Miguel A., Terrazas, Teresa, Sánchez, Daniel, Reyes, Pablo Carrillo- & Ruiz-Sanchez, Eduardo, 2023, Culm anatomy of the genus Otatea (Poaceae, Bambusoideae, Bambuseae, Guaduinae) as a contribution to Mexican species identification, Phytotaxa 609 (2), pp. 75-102 : 96-97

Key to Mexican Otatea species based on culm characters in cross section

1. Culm hollow .......................................................................................................................................................................................2

- Culm solid ..........................................................................................................................................................................................5

2. Transitional and central vascular bundles with fiber sheath composed of cells with strongly lignified walls...................................3

- Transitional and central vascular bundles with fiber sheath composed of cells with weakly lignified walls ....................................4

3. Vascular cycles 5–6; depressed central vascular bundles............................................................................................. O. reynosoana

- Vascular cycles 9–10; ovate central vascular bundles....................................................................................................... O. victoriae

4. Vascular cycles 10–11; frequent amorphous silica bodies occupying cellular spaces on fiber sheath; conical silica bodies absent... ........................................................................................................................................................................................... O. carrilloi

- Vascular cycles 8–9; sporadic amorphous silica bodies occupying cellular spaces on fiber sheath; intercellular conical silica bodies on ground tissue occupying and area of 6 (4–7) µm 2 ........................................................................................................... O. glauca

5. Transitional and central vascular bundles with fibr sheath composed of cells with strongly lignified walls ....................................6

- Transitional and central vascular bundles with fiber sheath composed of cells with weakly lignified walls ...... O. acuminata OAX

6. Thick epidermis 22 (20–23) µm and thick cortex 84 (73–93) µm and these two structures strongly and equally lignified ............... ................................................................................................................................................................................... Otatea sp. nov. 2

- Thin epidermis (<20 µm) and variable size cortex (≤ 77 µm) and these two layers with different patterns of lignification ...........7

7. Absence of conical silica bodies in ground tissue..............................................................................................................................8

- Presence of conical silica bodies in ground tissue............................................................................................................................10

8. Elliptical central vascular bundles with frequent amorphous silica bodies occupying cellular spaces on fiber sheaths ..................... ................................................................................................................................................................................. O. transvolcanica

- Ovate central vascular bundles with sporadic amorphous silica bodies occupying cellular spaces on fiber sheaths ........................9

9. Cortex with 3–4 layers of thick-walled rounded cells, followed by 1–2 layers of thinner-walled rounded cells (5–6 layers in total, 41 (37–45) µm length)............................................................................................................................................ O. acuminata JAL

- Thin cortex with a layer of narrow thick-walled rounded cells followed by 2 layers of wider, thinner-walled, ovoidal cells (3 layers in total, 27 (23–31) µm length) ................................................................................................................................. Otatea sp. nov. 1

10. Thick cortex> 65µm ........................................................................................................................................................................11

- Thin cortex ≤ 40 µm ........................................................................................................................................................................12

11. Vascular bundles in 8–9 cycles; epidermis with axially elongated silica bodies .................................................. O. acuminata AGS

- Vascular bundles in 11–12 cycles; epidermis with frequent squared to rectangular silica bodies and prickle hairs on top ................ .......................................................................................................................................................................................... O. fimbriata

12. Absence of amorphous silica bodies occupying cellular spaces on fiber sheaths; vascular bundles in 5–6 cycles.........................13

- Presence of amorphous silica bodies occupying cellular spaces on fiber sheaths; vascular bundles in 9–11 cycles.......................14

13. Broadly depressed central vascular bundles, 180 (167–198) × 260 (243–281) µm............................................... O. rzedowskiorum

- Ovate central vascular bundles; 309 (280–325) × 304 (261–330) μm.............................................................................. O. ximenae

14. Ovate central vascular bundles, 275 (245–309) × 297 (256–317) μm ............................................................................. O. ramirezii

- Elliptical central vascular bundles; 484 (477–488) × 446 (427–466) μm............................................................. O. acuminata VER