Generic affiliations of species under Pyrostria group B
The results presented above clearly shows the polyphyly of Canthium as earlier observed by Lantz et al. ([2002]), Lantz and Bremer ([2004], [2005]) and Razafimandimbison et al. ([2009]). The four Canthium (C. gynochthodes, C. obovatifolium, C. oligophlebium and C. ramosii) should be excluded from Canthium s.s. since these species are spineless.
The phylogenetic position of C. obovatifolium, C. oligophlebium and C. ramosii within the Pyrostria clade was already anticipated due to the presence of a persistent, basally paired, connate to acuminate bracts as observed in our recent collections and available herbarium sheets. The synapomorphic characters of Pyrostria such as dioecious sexuality and fleshy corolla with trichomes in the throat (Lantz and Bremer [2004]) were also observed in our sampled Canthium species. The placement of these three Canthium species in Pyrostria s.l. was already suggested by Bridson ([1987]) but she was unsure of the placement in the genus due to their geographical occurrence falling outside the known range, i.e. at that time Pyrostria was considered to be a predominately Afro-Madagascan genus.
Although Pyrostria is mostly represented in Africa, Ruhsam et al. ([2008]) mentioned that the presence of SE Asian Pyrostria could probably be a disjunct part of their African relatives. There is a possibility that species under this genus may have undergone long range dispersal from Africa to Asia as in the case of Mussaenda L. (Alejandro et al. [2005]).
Meanwhile, the phylogenetic placement of C. gynochthodes within Psydrax does not support the earlier suggestion of Bridson ([1985]) in placing the species under Pyrostria s.l.. Bridson may have assigned this SE Asian species under Pyrostria group B due to the presence of bracts which resembles that of Pyrostria although Baillon ([1879]) did not mention the occurrence of this character. However, we examined herbarium sheets of C. gynochthodes [Gaerlan, F.J.M 0542753 (L, PNH); Romero, E.M. 0542751 (L, PNH); Soejarto, D.D. 0219674 (L, PNH); Arriola and Alejandro, 12442 (PNH, USTH); Arriola and Alejandro, 11057 (PNH, USTH)] and revealed that bracts exist in younger inflorescences but totally absent in older ones. The presence of bracts on young inflorescences of C. gynochthodes will not affect its close relatedness with Psydrax. According to Bridson ([1987]) bracts may be present in some representatives of Psydrax, however, it is distinctive from the paired connate bracts of Pyrostria which are rare in Vanguerieae. The presence of bracts is not a cardinal character to delimit Psydrax. For instance, Bridson ([1985]) mentioned of the occurrence of bracts in the Indian Psydrax umbellata (Whit.) Bridson and unnamed Malayan species. Furthermore, examination of C. gynochthodes revealed that it posseses other diagnostic features of Psydrax such as coriaceous leaf blades, keeled stipules with truncate to triangular stipular base and falcate stipular apex, reflexed anthers, long style always exceeding the corolla tube, longer than wide stigmatic knob, cartilaginous seed and a very shallow to nearly inconspicuous apical crest without a lid-like area in the pyrene (Bridson [1985]; Cheek and Sonke [2004]). Additionally, the occurrence of a unique insertion of 40 bp in the trnL-F region of Psydrax that is non-alignable with other species of Vanguerieae (Lantz and Bremer [2004]) exists in C. gynochthodes.
The close relatedness of species placed under Pyrostria group B with Pyrostria s.s. and Psydrax are supported by morphology and molecular data. Therefore, it is necessary to recollect the remaining species of Pyrostria group B to determine their correct generic affiliations within the tribe.
Taxonomic treatment
We present here novel combinations of four species that were included in our study (Figure 2).
Pyrostria obovatifolia (Merr.) Wong, Magdaleno & Alejandro, comb. nov. Basionym: Canthium obovatifolium (Merr.) Merr., Philipp. J. Sci. 35 (1928) 8. Plectronia obovatifolia Merr., Philipp. J. Sci. C12 (1917) 167. Philippines, Luzon, Tayabas Prov. Mount Dalindingan, Sept. 1916, Ramos and Edano 26526 (holotype: PNH destroyed; lectotype: designated here K!; isolectotypes: US, HUH) (Figure 2A).
Shrub to small tree less than 3 m high; branches terete to a more or less quadrangular and glabrous. Leaves obovate, 3.5-7.5 × 1.0-3.0 cm, glabrous on both sides; apex rounded; base acute to acuminate; visible lateral nerves 3 to 4 on each side of the midrib; petiole 2.5-8.0 mm, glabrous. Stipules triangular to broadly ovate, 5.0-6.0 × 1.0 mm, glabrous on both sides. Female inflorescences axillary on 3.0-5.5 mm long peduncles, 6-flowered; peduncular bracts present, 3.0-5.5 mm long, triangular to broadly triangular, glabrous on both sides, enclosing the young inflorescence; pedicels erect, 3.0-4.0 mm long at flowering. Female flowers: calyx limb glabrous; tube 1.2- 2.5 mm long; lobes acuminate, 0.2 × 0.4 mm. Corolla 5-merous, white, glabrous outside; tube tubular, 0.8-1.2 mm long, hairs present at the throat; lobes broadly triangular, 2.0-2.5 × 1.0-1.2 mm, recurved. Stamens exerted, attached to corolla tube; anthers narrowly ovate to ovate, 0.3 mm long, exserted. Style including stigmatic knob 3.0-3.9 mm long; stigmatic knob 1 mm long, with a shallow cleft above, style not recessed into the stigmatic head; disk glabrous. Ovary 2-locular. Male flower unknown. Fruits ovoid 8.5-10.5 mm, glabrous.
Distribution:-Luzon Island: Ilocos Norte, Quezon
Habitat:-In secondary forest; 200-350 m altitude.
Phenology:- Flowering from March to June; Fruiting May to December
Taxonomic notes: This species approaches P. subsessifolia by its elliptic to ovate leaf shape but differs by its less conspicuous lateral nerves, shorter bracts and non- keeled fruits.
Pyrostria oligophlebia (Merr.) Pacia, Quiogue & Alejandro, comb. nov. Basionym: Canthium oligophlebium (Merr.) Merr., Philipp. J. Sci. 35 (1928) 8. Plectronia oligophlebia Merr., Philipp. J. Sci. 17 (1921) 442. Philippines, Luzon, Rizal Prov. Mount Susong Dalaga, Aug. 1917, Ramos and Edano 29342 (holotype, PNH destroyed; lectotype: designated here US; isolectotype: HUH, K !) (Figure 2B)
Shrub to small tree, less than 5.0 m high; branches quadrangular to more or less terete and glabrous. Leaves broadly lanceolate to oblong, 3.0-5.5 × 1.0-2.0 cm, glabrous on both sides; apex acute; base acute; visible lateral nerves 2 to 4 on each side of the midrib; petiole 0.7-1.0 mm, glabrous. Stipules broadly triangular to ovate, 1.0-2.0 × 1.0 mm, glabrous on both sides. Female inflorescences axillary on a glabrous peduncle less than 2 mm long, 7-12 flowered; peduncular bracts present, 2.5-3.0 mm long, triangular to broadly triangular, glabrous on both sides, enclosing the young inflorescence; pedicels erect, 4.0-5.0 mm long at flowering, persistent. Female flowers: calyx limb glabrous 2-2.7 mm long; lobes shortly toothed, 0.1 × 0.3 mm. Corolla 4-merous, white, glabrous outside; tube tubular, 0.8-1.2 mm long, hairs present at the throat; lobes broadly ovate, 2.0-2.5 × 1.0-1.2 mm. Stamens attached to corolla tube adjacent to the throat; anthers ovate, 0.3 mm long, exserted. Style including stigmatic knob 1.0-2.5 mm long; stigmatic knob 1 mm long, with a shallow cleft above; disk glabrous. Ovary 2-locular. Male flower unknown. Fruits ovoid 6.0-6.5 mm, glabrous with distinct indentation when dry.
Distribution:-Luzon Island: Rizal; Mindanao Island: Davao
Habitat:-In secondary forest; 500-900 m altitude.
Phenology:- Flowering from March to December; Fruiting from Septmber to February
Taxonomic notes: The smaller and fewer nerved leaves of P. oligophlebia approaches P. gynochthodes. However, P. oligophlebia differs from the latter by having persistent pair of bracts, many-flowered inflorescences and a longer petioles, peduncles and pedicel.
Pyrostria ramosii (Merr.) Arriola, Paraguison & Alejandro, comb. nov.
Basionym: Canthium ramosii (Merr.) Merr., Philipp. J. Sci. 35 (1928) 9. Plectronia ramosii Merr., Philipp. J. Sci. 7 (1921) 443. Philippines, Luzon, Tayabas Prov., Mount Umiray, June 1917, Ramos and Edano 28973 (holotype, PNH destroyed; lectotype: designated here NY!; isolectotype: K!) (Figure 2C)
Tree less than 9 m high; branches terete, glabrous. Leaves broadly lanceolate to oblong, 2.5-9.5 × 1.5-3.9 cm, glabrous on both sides; apex triangular to acuminate; base attenuate; visible lateral nerves 3 to 4 on each side of the midrib; petiole 1.5-2.0 mm, glabrous. Stipules triangular, 3.5-4.0 × 1.5-2.0 mm, glabrous on both sides. Inflorescences 4 flowered umbels; pedicels erect, 6.5-7.0 mm, persistent glabrous, peduncular bracts present, 0.5-1.5 mm long, triangular, glabrous on both sides. Infructiscence glabrous; stalk glabrous. Fruits ovoid to didymous 6.5-8.5 mm, 2 -celled, glabrous.
Distribution:-Luzon Island: Quezon
Habitat:-In secondary forest; 200-350 m altitude.
Phenology:- Fruiting August to December
Taxonomic notes: Pyrostria oligophlebia and P. ramosii closely resemble each other due to their oblong shape leaf with acuminate apex. However, the latter have longer peduncles and few (2-4) flowered umbellate inflorescences as compared to the numerous (7-12) flowered inflorescence of the former.
Psydrax gynochthodes (Baill.) Arriola, Yayen & Alejandro, comb. nov.
Basionym: Plectronia gynochthodes (Baill.) Merr., Enum. Philipp. Fl. Pl. 3 (1923) 536. Canthium gynochthodes Baill., Adansonia 12 (1879) 199. Philippines, Luzon, Batangas Prov., 1917, Cuming 1848 (holotype, K!) (Figure 2D)
Tree, less than 7 m tall; branches flattened to subterete, glabrous. Stipules glabrous on both sides, triangular to ovate, 2-4.5 mm, keel prominent on the abaxial side. Petioles 1.0-5.0 × 0.3-0.5 mm, glabrous; leaf blades leathery, elliptic to elliptic-oblong or obovate, 3-8.5 × 1.5-5 cm, base acute to broadly acute, apex obtuse, glabrous throughout, glossy; lateral nerves 3-4 on each side of the midrib, domatia present. Inflorescences axillary, 10-12(-several) flowered, glabrous; peduncle 0.8-2.5 mm, glabrous; pedicel 4.0-10.0 mm, puberulent. Calyx tube infundibuliform, 2-3 × 2.0-2.5 mm, glabrous; lobes triangular 1.5-2.0 mm. Corolla tube infundibuliform, 1.0-1.5 mm, glabrous outside, with ring of white hairs inside; lobes 4, triangular, glabrous outside and inside. Anthers 4, reflexed. Style 2-6 mm, exceeding corolla tube, stigmatic-knob longer than wide, 0.3 × 0.2 mm, bifid. Ovary bilocular, 1-ovule per locule. Fruits ovoid to didymous, distinctly broader than long, 7.5-8.0 × 9-10 mm, green when young, glabrous, calyx limb persistent; Seeds 2, obliquely ovoid, ventrally flattened, 2-5.5 × 3 mm, apical crest very shallow to nearly inconspicuous, pyrene cartilaginous.
Distribution:- Philippines, Taiwan
Habitat:-In secondary forest; 500-900 m altitude.
Phenology:- Flowering from March to June; Fruiting from June to December
Taxonomic notes: Psydrax gynochthodes is comparable with P. obovatifolia, P. oligophlebia and P. ramosii. However it is delineated from the three species due to the absence of persistent acuminate-connate bracts. For the above reason, we do not agree with the observation of Bridson ([1987]) that P. gyncochthodes is closely associated with P. villarii Vidal and that the two species should be synonymize. Moreover, P. gynochthodes can be distinguised from the Philippine P. amplifolia by its smaller, thicker and darker glossy green leaves, umbellate to cymose inflorescences, longer peduncles and smaller fruits.