Hegnera obcordata (Miq.) Schindler (1924: 285)

Jiang, Kai-Wen, Song, Zhu-Qiu, Pan, Bo, Zhao, Xue-Li, Li, Shi-Jin, Tu, Tie-Yao & Gong, Yan-Xiong, 2024, Hegnera obcordata (Fabaceae: Desmodieae), a newly recorded genus and species for the flora of China, Phytotaxa 644 (2), pp. 145-153 : 146-150

Hegnera obcordata (Miq.) Schindler (1924: 285) .

AEẍā/疊莢ā

≡ Uraria obcordata Miquel (1861: 305) . ≡ Desmodium obcordatum (Miq.) Kurz (1873: 229) .

Type:— INDONESIA. Sumatra orient., Prov. Palembang, prope Muaraduwa , J. E. Teysmann s.n. (holotype L, n.v., isotypes L0018948 , image!, K000858923 , image!) .

Description:— Creeping or climbing subshrub or shrub 3–4 m long. Branches covered with dense hooked hairs and mixed with few longer hairs. Leaves 3-foliolate. Stipules persistent, ovate, asymmetrical, 2.5–6(–7.5) × 1.5–2(–2.5) mm, long acuminated at apex, pubescent on both surfaces and along margin. Petiole 1.2–5.2 cm, hairy as branches, ± sulcate; rachis 0.5–2.4 cm, hairy as petiole; petiolules 1–2 mm, densely hairy. Stipels awl-shaped, persistent, 0.5–1 mm, hairy as petiolules. Leaflets obcordate or obtriangular, chartaceous, adaxial surface greenish, sparsely villous, abaxial surface greyish-green, sparsely villous and mixed with dense shorter and hooked hairs, denser along veins; terminal leaflet wider than long, 1–4.2 × 1.9–6.7(–9) cm, rounded or slightly retuse at base, obcordate to almost truncate at apex; lateral leaflets slightly asymmetrical, 0.7–3.7 × 0.7–3.5 cm; lateral veins 4–5 pairs, reaching margin. Inflorescence a terminal or axillary pseudoraceme, 2–20 cm, sometimes compounded into a panicle, flowers 1–2(– 4) per node; peduncle and rachis hairy as branches. Bracts scarious, striate, pubescent on both surfaces and along margin; primary bracts narrowly ovate, acuminate, usually entire, 2.5–5.5 × 1–1.5 mm, usually entire; secondary bracts narrowly triangular, 1–2 × 0.2–0.6 mm; bracteoles absent. Pedicel 2–3(–5) mm, slender, elongate towards fruiting, hairy as rachis. Calyx widely campanulate, 2.5–3.2 mm, hairy as pedicel, tube ca. 1 mm, 4-lobed: upper lobe widely triangular, bifid, 1.2–1.6 mm; lateral lobes triangular, 1.2–1.6 mm; lower lobe longest, triangular-acuminate, 1.5–2 mm. Corolla purplish-red to violet; standard widely elliptical, 6.5–7.5 × 6 mm, rounded at apex, wider at middle, auriculate at base, claw ca. 1 mm; wings narrowly elliptical, 6.5–7.5 × 1.5 mm, obtuse at apex, auriculate at base, claw 1.5–2 mm; keel petals 6–7 × 1.5–2 mm, obtuse or acute at apex, not auriculate at base, claw 1.5–2 mm. Stamens monadelphous, filaments fused, long and short alternately, one opposed to standard fused to others near base. Pistil 6–7.5 mm, densely hairy at base; ovary 1–5-ovuled; style ca. 2 mm. Loments stipitate, 1–2.5(–3) cm, stipe 1–3(–4) mm, flattened, indehiscent, scattered with both long and straight hairs, and short and hooked hairs, more dense along margin; articles 1–3(–5), U-shaped, 6–9 × 4–7 mm, ± imbricate, recurved et ends; sutures slightly thickened, the upper one deeply notched in the middle of the article, the lower one incised almost to the upper one. Seeds transversely elliptical, 2.5–2.8 × 3.7–4 mm, compressed, not or hardly arillate, with only a faint aril around the hilum.

Phenology:— Flowering in October; fruiting in November to December.

Distribution and habitat: — Hegnera obcordata is widely distributed across the Indochina Peninsula [ Cambodia, Laos, Myanmar (see Notes below), Thailand, Vietnam] as well as Western Malesia ( Dy Phon 1994, Ohashi 2004, Fig. 3 ). This study provides the first record of H. obcordata in China, from Hainan and Yunnan Provinces ( Fig. 3 ). According to Dy Phon (1994), this species occurs in the understory of dense forests, in secondary vegetation formations, on rocky slopes, and on sandy or clay soils. In the present study, we observed H. obcordata growing under rubber ( Hevea brasiliensis ) plantation in Xishuangbanna Prefecture, Yunnan Province, representing a northward range expansion from its previously documented distribution. The Hainan population was found under a secondary forest, consistent with previous reports.

Notes: —We traced a specimen deposited at herbarium U (s.coll. 3909 H.B.; see Specimens examined below) that was labelled as " type ". However, this specimen has not been recognized as a type in previous studies ( Dy Phon 1994, Ohashi 2004). Consistent with earlier treatments, we did not tentatively recognize this specimen as a type. Details of the type designation require further investigation.

Hegnera obcordata was reported from Myanmar by Ohashi (1973), Lock & Heald (2000) as well as Ohashi (2004). However, although Ohashi (1973) cited a collection from Tenasserim (S. Kurz s.n.) under this species, we were unable to locate that specimen or any additional specimens to confirm its occurrence in Myanmar. Therefore, the distribution of H. obcordata in Myanmar is not represented on the map in Fig. 3 .

Conservation status: —The Area of Occupancy (AOO) and Extent of Occurrence (EOO) were calculated for Hegnera obcordata using GeoCAT ( Bachman et al. 2011). The analysis estimated an AOO of 92 km 2, meeting the criteria for Endangered (EN) under this metric. Meanwhile, the estimated EOO was 2,944,677.620 km 2, reflecting a Least Concern (LC) assessment when considering EOO alone. Integrating these findings according to IUCN criteria ( IUCN Standards and Petitions Subcommittee 2022), Hegnera obcordata is concluded to have an overall Red List category of Least Concern (LC). This assessment recognizes the species has a relatively large geographic range, despite some localized threats reflected in its small estimated AOO.

Specimens examined:— CAMBODIA. Kampot: Kamchay près de Kampot, 16 November 1933, E. Poilane 22850 (P). Nord de Kampot, 3 February 1928, E. Poilane 14617 (P). Mt. Chung: December 1867, L. Pierre s.n. (P). Oddar Meanchey: entre Samrong et Anlong Veng, pied du Massif des Dangrek, 30 October 1927, E. Poilane 13844 (L, P). CHINA. Hainan: Changjiang, Langyue Lishe Guesthouse, in sloping forests, alt. 365 m, 28 December 2023, H. Y. Li & J. H. Wu LiHY1215 (IBSC, NPH). Yunnan: Xishuangbanna, Jinghong, Jingha, Geniu Village, 26 October 2023, Y. X. Gong, L. P. Wei & S. R. Luo G963 (HITBC, NPH). ibid., 21 November 2023, K. Chiang & H. F. Cen KC1270 (CSH, IBSC, NPH). INDONESIA. Archip. Ind. Madoera, N. van Soemenep, 26 March 1915, C. A. Backer 20727 (L). In siccis Pame Kassan meridion, s.coll. s.n. (L). Java: H. Zollinger 1628 (NY). Sumatra: Moearadoewa, Palemb, s.coll. 3909 H. B. (U). LAOS. Vientiane: Env. Bankeun, 14 October 1965, J. E. Vidal 4025 (P). Env. de Vientiane, 24 October 1948, J. E. Vidal 668B (P). MALAYSIA. Kedah: Kelubi Estate, December 1933, M. R. Henderson s.n. (NY). THAILAND. Central: Saraburi: Muang, Praputtachai (Sahm Lahn) National Park, along the trail from Po Hin Daht Falls to Kow Pang Mah (hill), 22 October 2004, J. F. Maxwell 04-618 (CMU, L). Sahm Lahn, 26 January 1975, R. Geesink & J. F. Maxwell 8379 (L). ibid., 13 October 1973, J. F. Maxwell 73-452 (AAU). ibid. 14 October 1973, J. F. Maxwell 73-498 (AAU). Eastern: Chaiyaphum: Nam Phrom, 11 December 1971, C. F. van Beusekom, C. Phengkhlai, R. Geesink & B. Wongwan 4135 (L, P). Chonburi: Bahn Beung, Ta Jahm, 16 November 1975, J. F. Maxwell 75-1080 (AAU, L). Northeastern: Nakhon Ratchasima: Khao Yai National Park, Kong Keo, 9 July 1966, K. Larsen, T. Smithnand & E. Warncke 192 (AAU). "TREND-Camp" near Pak Thong Chai, eastern part of Khao Yai National Park, 2 November 1970, C. Charoenphol, K. Larsen & E. Warncke 4469 (AAU). Nongkhai: along route 211, by Mekhong river, 10 November 1984, G. Murata, S. Mitsuta, T. Yahara, H. Nagamasu & N. Nantasan 50453 (L). Si Sa Ket: Kantaralak, Khao Phra Vihan NP, Gluaimai (Orchids) Nature trail, 21 December 2005, R. Pooma, K. Phattarahirankanok, S. Sirimongkol & M. Poopath M (AAU, E, L). [as Sesekhêt], January 1877, F. J. Harmand 992 (P). Kunhn Hahn, Panom Dongrak Wildlife Sanctuary, Bahk Sawng Subdistrict, south of the end of Highway 2236, c. km 17, near Sahm Lahn Falls, 22 October 2003, J. F. Maxwell 03-380 (CMU, L). Southern: Songkhla: Muang, Suan Dtoon Falls, 16 November 1984, J. F. Maxwell 4-428 (P). Without detailed information: 4 October 1930, Put 3211 (AAU). 1866–1868, C. Thorel s.n. (P). VIETNAM. Annam: Phanrang, vallée du Song Cay, 27 September 1940, E. Poilane 30605 (P). B. Nieng (Datlat W), November 1949, M. Schmid 763 (P). Dong Nai: Bienhoa, Baria, October 1866, L. Pierre s.n. (NY, P). Haut Donaï: km 98 route n° 20, montée du Col de Blao, délégation de Djiring, 21 October 1931, E. Poilane 19828 (P). Lam: 1 November 1907, M. Mouret 56 (P). Lam Dong: Da Lat, 14 December 1995, N. G. Prilepsky 3807 (MW). Lang Bian: entre Ban Dlé et Dankia, 23 October 1930, E. Poilane 18588 (P). Ouonbi: dans les broussailles, November 1885, B. Balansa 1242 (L, P). Pongour: bord du Dai Ninh env. de Da Lat, 1 May 1959, P. Tixier s.n. (P). Quang Tri: Lao Bao, 27 December 1924, E. Poilane 11358 (P). Without detailed information: 1866–1868, C. Thorel 1439 (P).

Figures

FIGURE 3. Distribution map of Hegnera obcordata (Miq.) Schindl. based on specimens examined (red dots, using the software ArcGIS 10.5).