Agrostis turrialbae Mez, Repert. Spec. Nov. Regni Veg. 18(1-3): 4. 1922.

Vigosa-Mercado, J. Luis, Delgado-Salinas, Alfonso, Alvarado Cardenas, Leonardo O. & Eguiarte, Luis E., 2023, Revision of the genus Agrostis (Poaceae, Pooideae, Poeae) in Megamexico, PhytoKeys 230, pp. 157-256 : 157

19. Agrostis turrialbae Mez, Repert. Spec. Nov. Regni Veg. 18(1-3): 4. 1922.

Figs 4R , 30F , 38

= Agrostis arcta Swallen, Contr. U.S. Natl. Herb. 29(9): 405. 1950. Type. Guatemala. Chimaltenango: moist roadside at Santa Elena, 17 Jul 1933, A.F. Skutch 422 (holotype: US (US00131720)).

= Agrostis vesca Swallen, Contr. U.S. Natl. Herb. 29(9): 405. 1950. Type. Guatemala. Chimaltenango: moist roadside at Santa Elena, 17 Jul 1933, A.F. Skutch 420 (holotype: US (US00131129)).

Type.

Costa Rica. Cartago: plateau au field W du Turrialba , 2600 m alt., 27 Jan 1884, H. Pittier 855 (holotype: B; isotypes: US ( US 00131127, US04023770 [image!])) .

Description.

Plants perennial, caespitose. Tillers extravaginal, with cataphylls. Culms 13-32 cm long, erect, nodes 1-2, glabrous, internodes glabrous. Leaves mostly basal; sheaths 0.8-6.5(-10) cm long, usually longer than the internodes, glabrous or scaberulous; ligules 0.5-1.6 mm long, longer than wide, dorsally scaberulous, apices acute to rounded, erose or lacerate; blades 1-9 cm long, 0.2-0.5 mm wide, filiform, conduplicate to involute, rarely flat in the upper leaves, scaberulous on both surfaces. Panicles 3.8-10 cm long, 1.7-5(-8) cm wide, open, lax, ovate, exserted from the upper sheaths; branches ascending to spreading, rebranching about or slightly above mid-length, scaberulous, without spikelets near their base, inferior branches 0.7-2.5 cm long; pedicels 0.7-4 mm long, ascending to spreading, scaberulous. Spikelets 1.5-2.4 mm long, purplish; glumes subequal to unequal, lanceolate, apices acute, 1-veined, scaberulous on the keel, lower glume 1.5-2.4 mm long, upper glume 1.4-2.3 mm long; callus pubescent, with 2 bunches of trichomes; lemmas 1.3-1.8 mm long, elliptic, apices entire, acute, sometimes irregularly toothed, 5-veined, veins prominent, unawned, rarely awned near the apices, awn ca. 0.2 mm long, straight; paleas absent or up to 0.2 mm long, veinless, glabrous; anthers 3, ca. 0.7 mm long. Caryopsis 1.5-2.2 mm elliptic; endosperm solid. 2n= unknown.

Anatomy and micromorphology.

Leaf blades v-shaped to involute in transversal section; adaxial furrows deep, narrow; adaxial ribs rounded to triangular; keel absent; first order bundles circular in outline, sheath interrupted abaxially, abaxial and adaxial sclerenchyma in strands; second order bundles circular in outline, sheath interrupted abaxially, abaxial and adaxial sclerenchyma in strands; intercostal sclerenchyma present, abaxial; leaf margins with well-developed sclerenchyma caps, rounded; colorless cells absent (Fig. 37C, D ). Lemmas with transversal thickenings irregular to oblong, wider than the unthickened portion of the wall; prickle hairs present, abundant (Fig. 32F ).

Distribution and habitat.

Agrostis turrialbae is distributed from central Mexico to Costa Rica. It has also been reported from Colombia and Venezuela ( Luteyn 1999; Soreng and Peterson 2003). In the study zone, this species has been collected in the Mexican states of Chiapas, México, Querétaro, Tlaxcala, and Veracruz, and the Guatemalan departments of Huehuetenango and San Marcos (Fig. 39A ). It has also been reported from Hidalgo ( Sánchez-Ken 2019), but no specimens from this state were seen. Agrostis turrialbae grows in open areas of temperate forests, with Pinus and Quercus , and alpine grasslands, between 1600-4240 m a.s.l. (Fig. 27G ).

Phenology.

Specimens with spikelets have been collected from June to February (Fig. 28G ).

Commentaries.

Populations of this species from central Mexico have been confused with A. subpatens by some authors (e.g., Acosta 2001; Vigosa-Mercado and Ruiz-Sánchez 2020) (see the note under the description of that species). Agrostis turrialbae is similar to A. perennans sensu lato, and its identity has been put in doubt recently by Sylvester et al. (2020a). Both species share open panicles and unawned lemmas, as well as several lemma micromorphology characters. In the study zone, it has been found that the plants identified as A. turrialbae are consistently different from A. perennans , and are characterized by the small size of the plants, mostly basal leaves, leaf blades narrow and conduplicated to involute, with adaxial ribs rounded to triangular, with abaxial intercostal sclerenchyma, and purplish spikelets (vs. usually larger plants, usually basal and cauline leaves, but the basal ones often drying at anthesis, leaf blades wider and flat, with rounded adaxial ribs, without intercostal sclerenchyma, greenish to purplish spikelets in A. perennans ). This species is scarcely different from A. idahoensis , from the southern USA (see the note under the description of that species).

Conservation status.

Agrostis turrialbae is a widespread species in the study zone. It is represented by 30 collections, with several populations occurring in six protected areas. The EOO is 183,426 km2 and the AOO is 84 km2. Following the IUCN criteria, the preliminary assessment category is Least Concern (LC).

Representative specimens examined.

Guatemala. Huehuetenango: Municipio Santa Eulalia, top of cerro Chemalito , Sierra de los Cuchumatanes , 3.5 mi W of Santa Eulalia, [15.7822223°N, 91.5111111°W], 3100-3150 m alt., 2 Aug 1942, J.A. Steyermark 49905 (F, US). San Marcos: Municipio San Marcos, between San Sebastián and summit of Volcán Tajumulco, [15.04824546°N, 91.86726456°W, 3353 m alt.], 13 Feb 1940, J.A. Steyermark 35477 (F) . Mexico. Chiapas: Municipio Motozintla , near summit of cerro Mozotal., [15.419722°N, 92.336667°W], 2750 m alt., 24 Nov 1981, D.E. Breedlove and B.M. Bartholomew 55845 (MO) . México: Municipio Amecameca: ladera SW del volcán Iztaccíhuatl, rumbo al primer Portillo , 19.13697222°N, 98.64898611°W, 4050 m alt., 8 Nov 2014, R. Hernández and S. Villalobos 2057 (IEB, MEXU [**]). Querétaro: Municipio Colón, antena El Zamorano, [20.93305556°N, 100.1797222°W], 3355 m alt., 24 Nov 1981, A. Mora and J. Ramírez 401-AMB (MEXU [*,**]). Municipio Landa, Lobo, [21.29275°N, 99.11930833°W], 1600 m alt., 24 Aug 1982, R. Guzmán 5959 (MEXU [*, **]). Tlaxcala: Municipio Huamantla, ladera N del Volcan La Malinche , 19.23486111°N, 98.03338889°W, 4190 m alt., 29 Jun 2013, R. Hernández-Cárdenas and L. Arredondo-Amezcua 1123 (IEB), 1929 (IEB). Veracruz: Municipio Calcahualco, La Cuchilla, camino al Pico de Orizaba , por Coscomatepec, [19.06728503°N, 97.19152382°W], 3160 m alt., 22 Jul 1982, R. Guzmán 5847 (MEXU). See Suppl. material 2 for the full list of examined specimens .

Figures

Figure 4. Florets of Agrostis species observed with SEM A A. bourgaei B A. calderoniae C A. capillaris D A. elliottiana E A. exarata F A. ghiesbreghtii G A. gigantea H A. hyemalis I A. laxissima J A. microphylla K A. pallens L A. perennans M A. scabra N A. stolonifera O A. subpatens P A. subrepens Q A. tolucensis R A. turrialbae S A. variabilis. Scale bars: 0.3 mm.

Figure 27. Elevation histograms of Agrostis species A A. perennans B A. scabra C A. stolonifera D A. subpatens E A. subrepens F A. tolucensis G A. turrialbae H A. variabilis.

Figure 28. Phenology histograms of Agrostis species A A. perennans B A. scabra C A. stolonifera D A. subpatens E A. subrepens F A. tolucensis G A. turrialbae H A. variabilis.

Figure 30. Calluses of Agrostis species observed with SEM A A. scabra B A. stolonifera C A. subpatens D A. subrepens E A. tolucensis F A. turrialbae G A. variabilis. Scale bars: 50 μm.

Figure 32. Lemma surface of Agrostis observed with SEM A A. scabra B A. stolonifera C A. subpatens D A. subrepens E A. tolucensis F A. turrialbae G A. variabilis. Scale bars: 15 μm.

Figure 37. Leaf blade anatomy in transversal section of Agrostis species, in general view, and details of lateral bundles. A, B A. tolucensis C, D A. turrialbae E, F A. variabilis. Scale bars: 0.1 mm.

Figure 38. Agrostis turrialbae A whole plant B ligular area C spikelet E floret, abaxial view F floret, adaxial view. Based on Guzman 5959 (MEXU). Scale bars: 3 cm (A); 1 mm (B); 0.5 mm (C); 0.2 mm (D, E).

Figure 39. Map of known geographic distribution of Agrostis species, based on herbarium specimen data A A. turrialbae B A. variabilis.