Ticanto xylocarpa K. W. Jiang & Shi J. Li, 2024

Ticanto xylocarpa K. W. Jiang & Shi J. Li , sp. nov. Figs. 1 View FIGURE 1 , 2 View FIGURE 2 & 3 View FIGURE 3 .

Type:— CHINA. Guangdong: Yangjiang, Yangchun, Bajia, the vicinity of Antangdi, climbing on trees, alt. 129 m, 15 April 2023 (fl.), S. J. Li, L. Li, H. Y. Li, W. T. Yang & G. D. Chen lishijin5182 [holotype: NPH (herb. no. 2249!), isotypes: IBSC (barcodes IBSC 0916951!, IBSC 0916952!), NPH (herb. no. 2250!)].

Diagnosis: — Ticanto xylocarpa most closely resembles T. magnifoliolata in its coriaceous leaflets usually 2–3-jugate per pinna and ferruginous young branches and inflorescence axes, but can be readily distinguished from the latter by its ferruginous ovary (vs. glabrous), as well as ligneous (vs. coriaceous), dehiscent (vs. indehiscent) and wingless (vs. ventral suture extending to both sides and forming a carinate narrow wing) pods.

Description: —Woody climber. Branches densely ferruginous, glabrescent when old; sparsely armed with recurved prickles. Stipules unknown. Leaves pari-bipinnate, rachis and petiole 5.5–42 cm, ferruginous, glabrescent when old, usually sparsely to moderately armed with recurved prickles, these usually paired at pinna insertion points and scattered on the internodes, or rarely prickles absent; pinnae 2–3-jugate, opposite, rachis indumentum as leaf rachis, recurved prickles sparse or sometimes absent, with an appendage ca. 0.5 mm long at apex; leaflets (1–)2–3- jugate per pinna, petiolules 3–7 mm, densely ferruginous when young but glabrescent, wrinkled, blade coriaceous, ovate, elliptic to obovate, 3.8–14.6 × 1.6–7.1 cm, broadly cuneate to rounded at base, usually ± oblique, usually obtuse at apex, less frequently rounded, rarely obtusely acuminate, adaxial surface moderately ferruginous with brownish, curled hairs when young, glabrescent, shiny when young, abaxially ferruginous as adaxial surface but denser, especially along midrib when young, glabrescent, dull. Inflorescence an axillary or terminal panicle, axes densely ferruginous, glabrescent when fruiting. Pedicels 4–6 mm, articulated ca. 1 mm below hypanthium, ferruginous as inflorescence axes. Flowers with a hypanthium ca. 1.5 × 4.0 mm, densely ferruginous. Sepals 5, outer surface moderately ferruginous near base, glabrous towards apex, inner surface glabrous, lower sepal cucullate, longest, ca. 6 × 1.5 mm, acute at apex, other sepals subequal, ca. 3 × 2 mm. Petals 5, yellowish, glabrous, median petal inrolled, with reddish nectar guide at middle part of blade and a patch of hairs at base of blade on inner surface, ca. 7 × 2 mm, lateral petals subequal but lower lateral petals somewhat oblique, ca. 2–2.5 × 5 mm, with a basal claw ca. 1 mm, glabrous. Stamens 10, 8–10 mm, the basal half tomentose with white hairs; anthers dorsifixed, ellipsoid, longitudinal. Ovary shortly stipitate, moderately ferruginous; style ca. 8 mm, sparsely hairy; stigma funnel-shaped. Pods suborbicular to broadly elliptic, 2.5–4.5 × 2.3–3.3 × 1–1.5 cm, ± asymmetric at base, with a short beak 1–1.5 mm at apex, ventral suture slightly arcuate to almost straight, dorsal suture semicircular; valves ligneous, dehiscent along both sutures when mature, somewhat thickened along ventral suture, with prominent and reticulate veins on both surfaces initially, these becoming obscure over time. Seeds black, irregular in shape, elliptic to sub-square, lenticular, occasionally retuse near hilum, 1.7–2.1 × 1.1–2 × ca. 0.8 cm.

Phenology: —Flowering in April; fruiting in October to December, with the fruits typically persisting on the plant though the seeds may have fallen.

Distribution and habitat: — Ticanto xylocarpa is currently known from southern China (Guangdong, Guangxi, and Hong Kong, Fig. 4 View FIGURE 4 ) based on fieldwork and herbarium studies conducted by the authors. Its distribution may also extend to northern Vietnam, as it has been collected from Mt. Shiwandashan in southern Guangxi Province, China – an area bordering northern Vietnam.

Ticanto xylocarpa typically occurs in montane areas below 1000 m, where the bedrock is mudstone or granite.

Etymology: —The specific epithet xylocarpa derives from Ancient Greek ξύλον (xúlon, “wood”) and κᾰρπός (karpós, “fruit, grain”), referring to the ligneous pod valves that characterize Ticanto xylocarpa .

The Chinese name for Ticanto xylocarpa is provided here as †ẍ南天ª / †*南天ª, 南天ª is the common Chinese name for the genus Ticanto , while †ẍ / †* directly translated the specific epithet xylocarpa .

Conservation status: —The Area of Occupancy (AOO) and Extent of Occurrence (EOO) were calculated for Ticanto xylocarpa using GeoCAT (Bachman et al. 2011). The analysis yielded an AOO of 28 km 2, meeting the criteria for Endangered (EN) under this metric. Meanwhile, the estimated EOO was 87,971.884 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), Ticanto xylocarpa is concluded to have an overall Red List category of Least Concern (LC). This assessment recognizes that the species has a relatively large geographic range, despite the small estimated AOO, as AOO is usually an underestimation of the true AOO, since not all populations within the species' range are expected to be known.

Additional specimens examined (paratypes):— CHINA. Guangdong: Dianbai, Luokeng, Mt. Shuangjiling, mountainous area, in the valley, alt. 600 m, 8 August 2001, H. G. Ye 6379 (IBSC). Fengkai, Heishiding, in the mountain pit, 16 November 1980, G. Q. Ding & L. Yu 6680 (IBSC). Jiangmen, Mt. Gudoushan, 21 August 2009, X. X. Chen 2008040207 (SN). Ibid., 18 January 2010, C. Y. Zhang 2008040512 (SN). [Jiangmen], Mt. Gudoushan Natural Reserve, 28 May 2007, L. Y. Yi 200502509 (SN). Yangchun, Bajia, the vicinity of Antangdi, on the granite mountain, alt. 112 m, 15 April 2023, S. J. Li, L. Li, H. Y. Li, W. T. Yang & G. D. Chen lishijin5179 (IBSC, NPH). Yangchun, Hekou, Ehuangzhang Natural Reserve, roadside, climbing on trees, alt. 34.15 m, 12 July 2023, K. Chiang & Z. M. Li KC804 (IBSC, NPH). Yangchun, Hekou, Honghuatan, in the valley, under the sparse forest, alt. 119 m, 28 March 2001, H. G. Ye et al. 174 (IBSC). Yangchun, Ehuangzhang Nature Reserve, Honghuatan, mountainous area, in the valley, alt. 15 m, 8 May 2001, H. G. Ye et al. 540 1 (IBSC). Yangchun, Mt. Heweishan, Honghuatan Power Station, mountainous area, in the valley, alt. 200 m, 15 April 1991, N. Liu 1283 (IBSC). Guangxi: Fangcheng, Nasuo, Dongshan, in the sparse forest, climbing on thickets, 7 September 1957, H. Y. Liang 69295 (MO). Nanning, Me kon Seh-feng Dar Shan S, in thickets, alt. 2600 ft., 5 November 1928, R. C. Ching 8435 (IBSC, NAS, PE, WUK). Shangsi, Mt. Shiwandashan, Dong'an, Mt. Babaishan, Mt. Fengshan, in the valley, by the stream, on the tree, in the sparse forest, shady, moist place, alt. 300 m, S. C. Chen 4357 (IBSC). Shangsi, Mt. Shiwandashan, on the way back from Nalungou, on the slope, in thickets, alt. 400 m, 1 August 1982, P. C. Huang 427 (NF). Shangsi [Shang-sze], Mt. Shiwandashan [Shap Man Taai Shan], Denglong [Tang Lung] Village, 20 October 1934, W. T. Tsang 24516 (MO). Hong Kong: Without detailed information: September 1928, W. Y. Chun 7538 (IBSC).

Taxonomic remarks: —According to Clark et al. (2016), three Ticanto species were previously known to have ligneous pod valves,. T. caesia (Handel-Mazzett 1936: 215) R. Clark & Gagnon in Clark et al. (2022: 69), T. vernalis (Champion ex Bentham 1852: 77) R. Clark & Gagon in Clark et al. (2022: 81) and T. yunnanensis (Shi J. Li, D. X. Zhang & Z. Y. Chen 2006: 78) R. Clark & Gagon in Clark et al. (2022: 83). However, upon examination of herbarium specimens for the present study, we found that T. caesia bears coriaceous rather than ligneous pod valves. This coriaceous texture was initially reported by Handel-Mazzett (1936) when he first described the species, confirming our observations. The new species, T. xylocarpa K. W. Jiang & Shi J. Li described in this paper is the third Ticanto species with ligneous pod valves.

Morphologically, Ticanto xylocarpa is easily distinguished from the other two species with ligneous pod valves. Compared to T. vernalis , it has fewer pinnae per leaf (2–3-jugate vs. 8–16-jugate), fewer leaflets per pinna [(1–)2–3- jugate vs. 5–10-jugate], and larger leaflets (3.8–14.6 × 1.6–7.1 cm vs. 1.2–2.8 × 0.5–1.5 cm). Its leaflet apices are usually obtuse, less frequently rounded, rarely obtusely acuminate, contrasting with the acute apices in T. vernalis . Moreover, the pods of T. xylocarpa are 1-seeded and are shiny with prominent reticulate veins on both surfaces in their early stages of maturity ( Fig. 2M View FIGURE 2 , Fig 3 View FIGURE 3 B-a). In comparison, those of T. vernalis are (1–)2-seeded, i.e. generally 2-seeded, and the surface is dull with obscure veins. As for T. yunnanensis , additional specimens [ CHINA. Yunnan: Wenshan, Malipo, near Shen’gou, alt. ca. 600 m, 13 March 2023, K. Chiang, S. J. Li, H. F. Cen & B. Xiao KC310P1 (NPH). ibid., ead. die, coll. iid. KC310P2 (IBSC, NPH). ibid., ead. die, coll. iid. KC310P3 (NPH)] were observed. This species bears leaflets (2–)3–4-jugate per pinna, and the leaflet apices of T. yunnanensis are generally bluntly acute, differing from those of T. xylocarpa . We also observed that T. yunnanensis bears pods that are sometimes with a narrowed wing ca. 4 mm wide along the ventral suture, with 1–3 recalcitrant seeds per pod. Especially when bearing 2 or 3 seeds, the pods are obliquely oblong, these features are clearly different from T. xylocarpa , which has generally wingless, 1-seeded, suborbicular to broadly elliptic pods and orthodox seeds.

Although we have provided the key characters to distinguish Ticanto xylocarpa from T. magnifoliolata in the diagnosis, these two species may be difficult to differentiate when lacking fruits. Based on our observations, despite numerous exceptions, the leaflet apices of T. xylocarpa are more frequently obtuse, while those of T. magnifoliolata are often rounded or retuse. The flower morphologies of these two species are similar. Clark et al. (2022) recorded the ovary of T. magnifoliolata as glabrous, contrasting with the moderately ferruginous ovary of T. xylocarpa . This floral character may provisionally distinguish these species, our field observations also support this conclusion, but more observations are needed to confirm consistency across their ranges. Geographically, T. magnifoliolata occurs mainly in limestone regions of Guangdong, Guangxi, Guizhou and Yunnan Provinces of China, with a new record reported here in Vietnam [ VIETNAM. Cao Bang: Tra Linh, municipality Quoc Toan, vicinity of Thang Heng and Lung Tao villages near Thang Heng lake, broad-leaved evergreen closed primary forest on steep slopes and bluffs of limestone mesas and ridges, elev. 500–650 m, 25 May 1997, L. Averyanov et al. VH4846 (HN, MO)], there is only one reliable specimen record of this species in Guangdong Province [ CHINA. Guangdong: Luoding, Pingtang, Lianshi Village, in thickets, 6 November 1998, B. H. Chen et al. 1793 (IBSC)]. In contrast, T. xylocarpa , while overlapping partially with T. magnifoliolata , has been found mostly in mountainous mudstone or granite soils, and has not yet been recorded from limestone areas. Compared to T. magnifoliolata , T. xylocarpa appears to be more common in Guangdong Province based on current collection records ( Fig. 4 View FIGURE 4 ).

When lacking fruits, Ticanto xylocarpa may also be difficult to differentiate from the sympatric T. crista ( Linnaeus 1753: 380) R. Clark & Gagnon in Clark et al. (2022: 70). However, the inflorescence axes of T. crista are generally glabrous or sparsely tomentose, contrasting with the moderately ferruginous inflorescence axes of T. xylocarpa .