Chusquea matlatzinca L. G. Clark & Ruiz-Sanchez, 2013

Ruiz-Sanchez, Eduardo & Clark, Lynn G., 2013, Two new species of Chusquea (Poaceae: Bambusoideae: Bambuseae) from Mexico, one of them morphologically unusual, and a key to the Mexican sections of Chusquea, Phytotaxa 92 (1), pp. 1-12 : 3-7

Chusquea matlatzinca L. G. Clark & Ruiz-Sanchez , spec. nov., Fig. 1 A–I , Fig. 2 A–F

TYPE:— MEXICO. Michoacán: cañada que va al oeste de la cortina de la Laguna Larga, Los Azufres, ejido Taimeo Chico, municipio de Zinanpecuaro, bosque de Abies -Pinus, plantas creciendo en la base de la cañada húmeda con Quercus sp. , Smilax sp., 2654 m elevation, 19°47'48.2'' N, 100°41'42.3'' W, 9 June 2012, E. Ruiz-Sanchez & J. Álvarez 405 (Holotype: IEB!; isotypes: IBUG!, ISC!, MEXU!, MO!, NY!, US!, XAL!).

Chusquea matlatzinca differs from congeneric species in having hollow culms with thick walls, hispid culm leaves with deciduous blades, extravaginal branching and abaxially and adaxially strong tessellate foliage leaf blades.

Rhizomes pachymorph, short-necked. Culms (3)4.5–6(7) m tall, 1–3 cm in basal diameter, erect, somewhat arching toward apices. Internodes 15–23 cm long, 15–36 per culm, terete, glabrous, green with purple, with purple in some parts uncovered by the sheaths and some young culms totally purple derived from cut main culms, hollow, the walls 3–7 mm thick, the lacuna occupying <50% of the total diameter. Culm leaves 17–26 cm long, extending along almost the whole internode and some overlapping the next node, persistent and disintegrating on the culm, hispid, purple when young with thick brown-copper hairs 1–1.25 mm long, becoming straw-colored when old, hairs deciduous; sheaths 16–23 cm long, triangular with rounded shoulders, 8–11 times as long as the blade, the margins ciliate on both sides; blades 1–3 cm long, narrow triangular, erect, deciduous, apex short mucronate, margins finely ciliate or glabrous, with white cilia, abaxially hispid and adaxially glabrous; girdle 2 mm wide, densely pubescent, cilia 1–1.5 mm long golden in color; inner ligule ciliate, cilia 0.05 mm long. Nodes at mid culm with ca. 6–17 buds per complement, composed of one larger triangular central bud subtended by 5–16 smaller triangular, closely adjacent subsidiary buds of two sizes arranged in 1–2 rows in a linear to constellate arrangement, the base of the buds arising about 1 mm above the nodal line; prophylls with pubescent-hispid margins; nodal line more or less horizontal, supranodal ridge present and prominent. Branching extravaginal, the sheaths persistent as the branches develop, 5–18 branches per node, diverging from the main culm at 35–75 °, 30–70 cm long, 1–2 mm in diameter, rarely rebranching, the larger central branch 5–7 mm in diameter, up to 1.7 m long, always rebranching. Foliage leaves 9–12 per complement; sheaths slightly ciliate or glabrous, margin ciliate, the summit ciliate; blades 5–14 cm long, 1–2.5 cm wide, the blades dimorphic, adaxially and abaxially strongly tessellate, glabrous except the midrib abaxially ciliate at the blade base, the base rounded-attenuate, the apex subulate, the margin finely serrulate; pseudopetioles 2–3 mm long, adaxialy glabrous, abaxially hispid, inner ligule 0.5–1 mm long, truncate, abaxially pubescent; outer ligule a ciliate rim 0.1–0.2 mm long. Synflorescences not seen.

Habitat and distribution:— Chusquea matlatzinca is apparently a narrow endemic of the Trans-Mexican Volcanic Belt, in Michoacán state, where it forms a small population inhabiting a humid glen in pine-spruce forests at 2654–2750 m elevation.

Comparison:—On the basis of morphology, Chusquea matlatzinca resembles C. bilimekii and C. perotensis ( Table 2). All three are similar in habit with culms that are erect and somewhat arching toward the apices and in their foliage leaves that are similar in size and form. Chusquea perotensis and C. matlatzinca have hollow culms and C. bilimekii solid culms becoming fistulose with age. C. matlatzinca has thickerwalled culms and C. perotensis thinner-walled culms. C. matlatzinca has hispid culm leaves with deciduous blades whereas C. bilimekii and C. perotensis have glabrous culm leaves with persistent blades. The girdle in C. matlatzinca and C. bilimekii is pubescent but glabrous in C. perotensis . The three species all have one bigger triangular central bud, but C. perotensis has more subsidiary buds (40–50) than the other species (6–17) and the buds encircle the node (verticillate), whereas in C. bilimekii and C. matlatzinca the buds are linear to constellate. Chusquea matlatzinca has extravaginal branching and C. bilimekii and C. perotensis have intravaginal branching. The foliage leaf complement in C. matlatzinca has 9–12 leaves whereas C. bilimekii has 3–7 and C. perotensis 4–9. Foliage leaf blades in C. matlatzinca are abaxially and adaxially strongly tessellate, whereas in C. bilimekii they are adaxially often tessellate and abaxially tessellate and in C. perotensis adaxially not tessellate and abaxially not to weakly tessellate. C. matlatzinca grows in pine-spruce forests at 2654–2750 m in Michoacán, C. bilimekii grows in pine-oak forest at 2300–2800 m in Estado de México, Puebla, Oaxaca and Veracruz, and C. perotensis grows in cloud forests at 1900–2600 m in Oaxaca and Veracruz.

Etymology:—The specific epithet honors the Matlatzinca ethnic group that inhabited southwestern Estado de México, northern Guerrero and eastern Michoacán, Mexico, this last where the plants were collected. Phenology:—Flowers of this species have never been collected. Common name:—Carrizo (Spanish). Additional specimens examined:— MEXICO. Michoacán: Zinapécuaro, alrededores de Laguna Larga, Los Azufres, 2750 m, 7 December 1987, J. Rzedowski s.n. (IEB).

Key to the species of Chusquea sect. Longifoliae in Mexico (based on vegetative and reproductive characters)

1. Culms robust, 2–6 cm in diameter, solid becoming fistulose with age; culm leaf blades persistent; subsidiary buds at mid-culm nodes 18–80; spikelets 8.8–20.6 mm long, glume III 5–10.6 mm long, glume IV 7.6–15.5 mm long ....... 2

1. Culms thinner, to 1 cm in diameter, solid; culm leaf blades deciduous; subsidiary buds at mid-culm nodes 5–30; spikelets 5.5–8 mm long, glume III 3.3–4.6 mm long, glume IV 3.8–5.1 mm long .................................................... 3

2. Culm leaf blades 5.6–14.8 cm long, adaxially pubescent; subsidiary buds at mid-culm nodes 50–80; spikelets 8.8–11.8 mm long, glume III 5–8.4 mm long, glume IV 7.6–11 mm long ................... C. foliosa (1986: 61)

2. Culm leaf blades 1.4–8 cm long, adaxially scabrid; subsidiary buds at mid-culm nodes 18–30; spikelets 10.4–20.6 mm long, glume III 5.2–10.6 mm long, glume IV 8.6– 5.51 mm long ....................... C. longifolia (1940: 30)

3. Culm leaf sheaths with the overlapping margin fused above the base; foliage leaf blades yellowish-green, abaxially glabrous and tessellate; synflorescence an open panicle; glumes III and IV apiculate and subulate, glabrous ............. ...................................................................................................................................... C. aperta (1987: 74)

3. Culm leaf sheaths with the margins free; foliage leaf blades green-glaucous, abaxially pubescent, not tessellate; synflorescence a narrow congested panicle; glumes III and IV awned, pubescent............................................................ 4

4. Foliage leaf blades 0.5–1 cm wide, linear-laceolate; branches 15–30 per node, to 0.5 mm in diameter; synflorescences 4–6.5 cm long; spikelets 6.6–7.8 mm long, lemmas 6.4–7.1 mm long ............................................. C. nelsonii

4. Foliage leaf blades 1.1–1.8 cm wide, oblong-lanceolate; branches 5–10 per node, 1–1.5 mm in diameter; synflorescences 7–13 cm long; spikelets 5.5–6.5 mm long, lemmas 5–6 mm long.................................................... C. cortesii

Figures

FIGURE 1. Chusquea matlatzinca. A. Branch complement showing extravaginal branching. B. Culm internode showing hollow culm and thick walls. C. Bud complement. D. Culm with culm leaves. E. Foliage leaf complement. F. Foliage leaf ligular area, abaxial view. G. Detail of the tessellate venation pattern in the foliage leaf blades. H. Culm leaves abaxial view showing hispid indument. (based on Ruiz-Sanchez & Álvarez 405). Drawn by Alfonso Barbosa.

FIGURE 2. Chusquea matlazinca. A. Clumping bamboo, showing culms with different ages, new shoots and persistent culm leaves. B. Internode showing hollow culm with thick walls. C. Branch complement, showing the extravaginal branching pattern, partial culm leaves (mainly sheaths) and pubescent girdle. D. Apical culm, showing foliage leaf complements. E. Culm leaf abaxial view showing hispid brown indument and purple sheaths and blades. F. Young plant growing in the spruce-pine humid glen. Photos by E. Ruiz- Sanchez.