Glochidion acuminatum var. acuminatum

Yao, Gang & Zhang, Dianxiang, 2015, Taxonomic notes on Glochidion acuminatum and G. triandrum (Phyllanthaceae), Phytotaxa 236 (1), pp. 79-85 : 80-82

a. Glochidion acuminatum var. acuminatum

Glochidion hypoleucum (non Boerlage 1900: 275) Hayata (1920: 95). nom. illeg. Holotype:― CHINA. Taiwan: “Formosa, Holisha, Giochi”, 28 April 1916, B. Hayata s.n. (TI-01804!; isotypes: TI-01805! & TI-01806!).

G. hayatae Croizat & H. Hara (1940: 316) . Type:―The same as G. hypoleucum .

Leaves papery or membranous, subglabrous adaxially and sparsely pubescent abaxially. Capsules 5–7 mm in diameter; pedicels slender and long.

Distribution and habitat: ―This typical variety is widely distributed from Nepal, Sikkim, Assam, to southwest and South China, South Japan (Nansei-shoto), and Taiwan ( Fig. 3 ). Beille (1927) noted that this species is also distributed in Cambodia, but related specimen data was not available for the present study. The species grows in evergreen broad-leaved forests, open forests, valleys, or near stream, at the elevation of 500–2600 m.

b. Glochidion acuminatum var. siamense Airy Shaw (1972: 273) . G. trandrum var. siamense (Airy Shaw) P. T. Li (1988: 62) . Holotype:―THAILAD. Doi Sootep, open jungle, alt. 1676 m, 8 July 1910, Kerr 1321 (K-001081194!).

Leaves thickly papery, densely pubescent abaxially. Capsules up to 10 mm in diameter; pedicels robust and very short.

Distribution and habitat: ―This variety is distributed in China (Yunnan province) and Thailand ( Fig. 3 ). It usually grows in open, secondary growth conditions such as pine plantations, along the edges of forests, along roads, in thickets, or in evergreen broad-leaved forests, at the elevation of 1100–2100 m.

Discussion: ― Glochidion acuminatum var. siamense differs from the typical variety of G. acuminatum var. acuminatum by its thick papery and densely pubescent leaves, as well as its larger capsules on robust and short pedicels. Van Welzen (2007) provided a detailed description for the variety G. acuminatum var. siamense and cited the specimen Kerr 675 (K) as its holotype, while Airy Shaw (1972) designated the specimen Kerr 1321 (K!) as the holotype of this variety in its original description. Taxonomic discussion for the two species G. acuminatum and G. triantrum is provided under the later species.

Glochidion triandrum (Blanco) C. B. Robinson (1909: 92) . Kirganelia triandra Blanco (1837: 711) . Diasperus triandrus (Blanco) Kuntze (1891: 601) . Phyllanthus triandrus (Blanco) Müller Argoviensis (1865: 379) . Neotype (here designated):―PHILLIPINES. Camarines Province, Luzon, December 1913, E. D. Merrill Species Blancoanae 309 (US-00689060!, isoneotype P-04858208!]).

Glochidion eleutherostylum Müller Argoviensis (1863: 69) . Lectotype (here designated):― PHILIPPINES. Cuming n. 509 (P-00748463!, isolectotype GDC-00325049!).

Glochidion quinquestylum Elmer (1908: 303) . Lectotype (here designated):― PHILIPPINES. Luzon, Benguet Province, W of Sablan Falls , Baguio, March 1907, A. D. Elmer 8916 (K-001081226!, isolectotypes NY-00263449!, US-00109910!).

Trees, up to 10 m tall, monoecious. Stipules triangular, tiny; Leaves alternate, distichous, entire, ovate-lanceolate or lanceolate, 4.5–8 × 1.5–2.5 cm, papery or membranous, adaxially green, abaxially glaucous, subglabrous, base obtuse, inequilateral, apex acuminate; midvein slightly elevated, lateral veins slim, 5–7 pairs, not elevated; petiole 2–4 mm. Male flowers: pedicels 5–10 mm, slender; sepals 6, ovate or oblong-elliptic; stamens 3, connate. Female flowers: usually solitary in axillae, sessile; sepals 6; ovary tomentose, 4–5-locular; style 3–5, free, 1.5–2mm long, erect. Capsules depressed globose, diameter up to 10 mm, glabrous or slightly pubescent, shallowly 4–5-grooved or grooved obscurely, pericarp coriaceous, usually whitish or slightly reddish when matured; persistent style 3–5, free; fruiting pedicels 2–4 mm.

Distribution: ―This species is widely distributed in the northern and central Philippines ( Fig. 3 ), and grows in thickets and forests at low to medium altitudes.

Discussion: ― Blanco (1837) described many species (including Kirganelia triandra Blanco ) from the Philippines, but no related specimens have been recorded. Merrill (1918) provided his major commentary on these related species and cited most specimens that were called “illustrative specimen” for Blanco’s names. These related specimens were recognized as the neotypes of Blanco’s species by some subsequent authors ( Philcox 1968, Nicolson & Arculus 2001, Yao et al. 2015). Considering the Article 9.7 of ICN ( McNeill et al. 2012), one of Merrill’s “illustrative specimens” (Specimens Blancoanae No. 309) for Blanco’s name ( Kirganelia triandra ) deposited in different herbaria should be selected as the neotype of Glochidion triandrum . Finally, the specimen ( Fig. 1-B ) deposited at the Smithsonian ( US) is selected based on the suggestion provided by Nicolson & Arculus (2001). Müller (1866) provided a detailed description for his new combination Phyllanthus triandrus Müll. Arg. (Basionym: Kirganelia triandra Blanco ) based on a Philippine specimen (Cuming n. 509). However, this specimen is not proper as the accepted neotype of Glochidion triandrum , because it is the type of G. eleutherostylum Muell. Arg. , a name that was accepted as the synonym of Phyllanthus triandus in his study.

For Glochidion triandrum , although it is very similar to G. acuminatum in leaf morphology (lanceolate, adaxially green, abaxially glaucous, and basally unequal), other characters are quite different from the latter, such as its nonelevated lateral leaf veins ( Fig. 1-B ), typically axillary female flowers ( Fig. 2-B ), a 4–5-locular ovary, a 3–5 and free style ( Fig. 2-B, 2-C, 2-E ), a shallowly 4–5-grooved or obscurely grooved capsule, and a coriaceous pericarp ( Fig. 2-E ). Glochidion acuminatum has lateral veins on the leaves are elevated abaxially ( Fig. 1-A ), female flowers in axillary clusters ( Fig. 2-A ), a 3–4-locular ovary, a cylindric and connate style column ( Fig. 2-A ), a deeply 6- or 8-grooved capsule, and thin pericarp ( Fig. 2-D ). The field images (female flower, style, and capsule) of G. triandrum can be referred to in Nickrent et al. (2006 onwards).

Figures

FIGURE 1. A. Lectotype of Glochidion acuminatum (Wallich 7885, K); B. Neotype of G. triandrum (‘illustrative specimen’ of Merrill (1918), Specimens Blancoanae No. 309, US).

FIGURE 2. A. Female flowers of Glochidion acuminatum (Kawakita 0068, KYO); B. Female flowers of G. triandrum (Cuming 509, P); C. Ovary and style of G. triandrum (Cuming 509, G-DC); D. Fruits of G. acuminatum (Kawakita 0068, KYO); E. Fruits and styles (arrowhead) of G. triandrum (E. D. Merrill Species Blancoanae 309, P). Scar bars:A–C: 2 mm; D & E: 5 mm.

FIGURE 3. Distribution map of three Glochidion taxa: G. acuminatum var. acuminatum (■), G. acuminatum var. siamense (▲), G. triandrum (●).