Deyeuxia debilis (Hooker, 1896) Veldkamp

Paszko, Beata, Chen, Wen-Li & Szczepaniak, Magdalena, 2013, Deyeuxia debilis (Poaceae, Agrostidinae): typification, taxonomy and update of the Chinese distribution, Phytotaxa 135 (1), pp. 1-10 : 2-6

Deyeuxia debilis (Hook. f.) Veldkamp in Korthof & Veldkamp (1984: 220) ( Figs 1–4 )

Basionym: Calamagrostis debilis Hooker (1896: 262) .

Agrostis debilis (Hook. f.) Bor (1960: 387), hom. illeg., non Poiret (1810: 249).

Agrostis neodebilis Bennet & Raizada (1981: 433) .

Type:— INDIA. Sikkim: Himalaya, Chola , 11,000 ft [3350 m], s.d., Hooker s.n. (lectotype designated here: K000098590 !; isolectotype CAL!, K000098589 ! [possible isolectotype, without elevation]) .

Original protologue: Sikkim Himalaya; Chola, alt. 11,000 ft [3350 m], J.D. H. [ J.D. Hooker].

Previous lectotype designation: “Type K ” by Bor (1960: 387) .

Amended morphological description:—The inaccurate or incomplete description of Calamagrostis debilis is a source of confusion during identification. Studying the material examined here allowed us to discover additional morphological features to aid identification:

Perennial, loosely tufted with short rhizomes, culms 15–53 cm tall, nodes 2–5. Culm blades 2.3–19 cm long, 0.9–3.8 mm wide, adaxial leaf-blade surface moderately ribbed and scabrous, ligules 1.2–5.5 mm long, oblong, lacerate. Panicles 4–15 cm long, with 3–10 nodes, with 2–5 branches per node. Spikelets 1-flowered, laterally compressed, pedicels 0.5–2.5 times the length of the lower glume; glumes equal or subequal, smooth, or keel only lightly scabrous in the upper part, apices acute, lower glume 3.2–4.9 mm long, 0.9–1.3 mm broad (when flat), 1-veined, upper glume 3.0– 4.8 mm long, 0.8–1.3 mm broad (when flat), 1–3-veined, 0.94–1.1 times the length of the lower glume; callus hairs 2.5–3.8 mm long, 1–1.5 times the length of the lemma; lemmas 5-veined, 2.1–2.9 mm long, 0.55–0.70 times the length of the lower glume, apices 2–4-toothed, awn 3.2–6.0 mm long, straight, inserted above the midpoint of the lemma and exerted from the glumes; paleas 1.6– 2.3 mm long, 0.70–0.94 times the length of the lemma; rachilla extension always present, 0.3–0.9 mm long, sparsely hairy hairs 1.5–3.3 mm long; anthers 3, 0.35–0.75 mm long; caryopsis ca. 1.1 mm long, ca. 0.40 mm wide in dorsal view, ca. 0.35 mm wide in side view, elliptical in side-view, lightly compressed dorsiventrally, sulcus absent, hilum 0.12 mm long, embryo 0.2 times the length of caryopsis, endosperm hard, grain free from the palea, brown.

Original material: —Our search for Hooker’s collections of Calamagrostis debilis located two specimens at K, both annotated by Hooker, and a further six at CAL (2 sheets), GH (1 sheet), L (1 sheet), P (1 sheet), and W (1 sheet). Most original material housed outside Kew is not annotated by Hooker. There are eight herbarium sheets that come from collections made by Hooker at two elevations. The type material was collected at 11,000 ft (3350 m) and the other original material was collected at 10,000 ft (3050 m). All specimens were collected in Sikkim ( India) but only three sheets could be isotypes of the name Calamagrostis debilis :

(1) ‘ Calamagrostis 1’, Sikkim, Chola, 11,000 ft, 6 November 1849, Hooker f. s.n. ( K 000098590!) ( Fig. 1 ).―This herbarium sheet bears 8 flowering shoots and was annotated by Hooker as C. debilis . Confirmed isotype designated here as lectotype.

(2) ‘ Calamagrostis ’, Sikkim, Chola, 11,000 ft, 6 November 1849, Hooker f. s.n. ( CAL!).―This herbarium sheet bears 3 flowering shoots of C. debilis . Confirmed isotype designated here as isolectotype.

(3) ‘ Calamagrostis 1’, Sikkim, Chola, Hooker f. s.n. ( K 000098589!).―This herbarium sheet bears 8 flowering shoots and was annotated by Hooker as C. debilis . In the bottom right-hand corner is the word “ Type ” in unidentified handwriting. This is a possible isolectotype.

Review of original material: —Our survey indicates that Hooker’s two gatherings which are distributed across many herbaria constitute abundant, uniform, and complete material corresponding to the original description.

Bor (1960: 387) attempted to typify the name C. debilis with unspecified material in Kew. Korthof & Veldkamp (1984) noted that the holotype of C. debilis is at Kew and an isotype is at Leiden. Korthof & Veldkamp’s holotype citation is in conflict with the original protologue because they indicated original material from elevation of the type of C. debilis came from 10,000 ft (3050 m). Hooker (1896: 262) cited one locality and one gathering: Sikkim Himalaya: Chola, 11,000 ft (3350 m), J.D. H. [ J.D. Hooker]. We found only two specimens with that elevation, one at K and one at CAL. The K sheet of C. debilis ( K 000098590!) has Hooker’s identification and all the information needed to confirm it as the lectotype of C. debilis . On its herbarium label and field label there is information about its altitude (11,000 ft), precise locality (Chola), and collector name [ J.D. H.]. There are also sketches of the spikelets, likely made by Hooker f. (or by Stapf) showing the defining characters of C. debilis . One of the sheets at CAL is considered to be an isolectotype because the elevation and precise locality are the same as in the protologue, although it was not annotated by Hooker as C. debilis . The lectotype and isolectotype of C. debilis correspond to the current application of the name in local floras ( Bor 1960, Noltie 2000, Lu et al. 2006). The second K sheet ( K 000098589!) bears no information about its elevation, and can only be considered a ‘possible isotype’ despite being annotated by an unknown person as "Type".

Taxonomic remarks:— Hooker (1896: 262) gave no information about the rachilla extension in the protologue of Calamagrostis debilis other than the statement that it is present in his generic description. In the identification key for Agrostis provided by Bor (1960) C. debilis , included there within Agrostis , is treated among a group of taxa characterized by the absence of a rachilla extension. Korthof & Veldkamp (1984) did not explain their transfer of Calamagrostis debilis to Deyeuxia but the sheet of Calamagrostis debilis at L contains a note by Veldkamp: “rachilla is minute and long-hairy, therefore a Deyeuxia !”. In the description of C. debilis provided by Noltie (2000) and by Lu et al. (2006) it is noted that the rachilla extension is absent. Noltie’s (2000: 609) key to Calamagrostis indicates C. debilis , C. emodensis Grisebach (1868: 80) , and C. pseudophragmites ( Haller 1797: 11) Koeler (1802: 106) have a penicillate rachilla extension whereas C. nivicola ( Hooker 1896: 267) Handel-Mazzettii (1936: 1299) , C. scabrescens Grisebach (1868: 79) and their allies lack one. The opposite is in fact the case, except for C. debilis which does have a penicillate rachilla extension ( Fig. 2 ).

The stated absence of a rachilla extension in D. debilis ( Bor 1960, Noltie 1999, 2000, Lu et al. 2006) is erroneous. A poorly developed and sparsely hairy rachilla extension was observed in all the florets of D. debilis examined in this study.

Similar species: — Deyeuxia debilis is morphologically similar to two other Chinese species, D. gaoligongensis and D. moupinensis ( Table 1). All three species share a tufted growth habit (in the case of D. debilis , loosely tufted with short rhizomes) and are characterized by equal or subequal glumes, lower glumes 2.9–4.9 mm long, callus hairs subequal to the lemma or slightly longer (ratio 0.95–1.52), and the presence of a rachilla extension. Deyeuxia debilis differs from D. moupinensis by having longer ligules on the culm leaves (1.2–5.5 vs. 0.4–1.4 mm), different shape of the ligule apex (oblong vs. truncate, Fig. 4 ), different texture of the adaxial leaf-blade surface (moderately ribbed and scabrous vs. flat and smooth, Fig. 3 ), shorter anthers (0.3–0.8 vs. 0.9–1.9 mm), and a higher ratio of palea to lemma length (0.7–0.9 vs. 0.6–0.7). Deyeuxia debilis differs from D. gaoligongensis in the point of insertion of the awn (above the midpoint of the back of the lemma vs. below the midpoint of the back of the lemma), awn shape (straight vs. geniculate and twisted at the base) and awn length (3.2–6.0 vs. 3.5–8.2 mm, Table 1, Figs 2–4 ).

Distribution and habitats: — Deyeuxia debilis is known from Sikkim, India ( Hooker 1896, Bor 1960, Noltie 2000), and Bomi and Zayü counties in southeastern Xizang Province, China ( Lu et al. 2006). Its two close relatives D. gaoligongensis and D. moupinensis are only known from SW China. Deyeuxia gaoligongensis is is found in Gongshan county, Yunnan ( Paszko & Pendry 2013), and here we report it for the first time from Bomi county, Xizang. Deyeuxia moupinensis is found in the Baoxing, Beichuan, Mao, Meigu, Tianquan and Wenchuan counties of Sichuan Province.

specimens examined is in brackets after the species name.

Deyeuxia debilis was not listed by Li et al. (2000) in the Flora of Gaoligong Mountain or by Sun (2002) in the Flora Yunnanica. Li et al. (2000) reported D. moupinensis from Juliong in the Gongshan County, citing Wang’s 67256 as a voucher. We have not yet traced this collection. We did locate a collection of D. debilis, Wang 67258, collected from Champu-tung (Champutong) in the Gongshan County, Yunnan (A!, PE!). Wang 67258 was incorrectly determined as D. moupinensis , leaving the identity of 67256 in doubt.

We report the first records of D. debilis from northwestern Yunnan, where it was collected on the east and west slopes of the Gaoligong Shan at an elevation between 2500 and 3750 m ( Fig. 5 ). It grows in meadows among bamboo and Rhododendron shrubs, in thickets with scattered Abies and Larix , in alpine gravel areas and on grassy and rocky slopes of ravines.

Figures

FIGURE 1. Lectotype of Calamagrostis debilis (Hooker f. s.n., K). With permission from the Board of the Trustees of the RBG, Kew.

FIGURE 2. Diagnostic morphological characters of Deyeuxia debilis. A. spikelet, scale bar = 1 mm; B. Caryopsis in side view, scale bar = 1 mm; C. rachilla extensions from three different florets, scale bar = 1 mm; D. anthers, scale bar = 0.5 mm. A–B, from Hooker s.n. (GH); C–D, from GSBS 22535 (CAS).

FIGURE 3. Leaf blade adaxial surface. A. Deyeuxia debilis, Wang 67258 (PE); B. D. moupinensis, David s.n. (P). Scale bar = 0.5 mm.

FIGURE 4. Ligule. A. Deyeuxia debilis, Wang 67258 (PE); B. D. moupinensis, David s.n. (P). Scale bar = 1 mm.

FIGURE 5. Distribution of Deyeuxia debilis in the Gaoligong Shan region, China, marked in grey.