Capparis tagbanuorum Fici, 2016

Fici, Silvio, 2016, A new narrow-leaved species of Capparis (Capparaceae) from central Palawan, Philippines, Phytotaxa 267 (2), pp. 146-150 : 146-149

Capparis tagbanuorum Fici , sp. nov.

Type:– PHILIPPINES. Palawan: Narra, Victoria Peaks, Trident Mining Company concession area, 21 May 1984, Ridsdale SMHI 1792 (holotype L!).

Diagnosis:— A C. callophylla Blume foliis loratis, falcatis vel anguste lanceolatis, inflorescentia racemosa, petalis minoribus, staminumque numero superiore filamentis brevioribus praecipue differt. Praeterea ab ea petiolo breviore, antheris minoribus et gynophoro breviore distincta.

Climbing shrub. Twigs brown or reddish, weakly ribbed, glabrous or puberulous. Stipular thorns mostly present, straight, yellowish, up to c. 1 mm long. Petiole 4–7 mm, glabrescent. Leaf-blade subcoriaceous, glabrous, lorate, falcate or narrowly lanceolate, (4.8–) 8–9 times as long as wide, 9–19.5 × 1.1–3.6 cm; base acute; apex acute, mostly with a hardened tip; midrib above sunken; nerves c. 7–11 pairs, thin, decurrent along the margin. Flowers in terminal, loose racemes up to c. 12 cm long in the available material; pedicels 1.8–2.7 cm long, glabrescent or puberulous particularly in the distal part; bracts caducous, bracteoles caducous or sometimes persistent, up to 0.7 mm long. Sepals acute at apex, glabrescent, 8–12 × 3–4 mm, outer pair herbaceous, markedly concave, inner pair flatter and thinner, with membranaceous, ciliate margin. Petals oblong or obovate, 13–16 × 4–7 mm, pubescent outside at the apex and at the margins, the upper pair white, the lower pair recorded greenish or red-purple. Stamens c. 78–100; filaments (2–) 2.2–3 cm long; anthers basifixed, recurved, c. 1 mm long. Pistil with a 1.7–2.2 cm long gynophore, glabrous; ovary narrowly ovoid to ellipsoid, c. 3–3.2 mm long, glabrescent; stigma distinctly knob-shaped, ciliate. Fruit unknown. Fig. 1 .

The holotype, Ridsdale SMHI 1792, consists of a single specimen mounted on two herbarium sheets. Of these the sheet 1 (L1851396) includes a fertile branch, the sheet 2 (L1851397) a vegetative branch.

Etymology:— The specific epithet was named after the Tagbanua or Tagbanwa people, one of the most ancient ethnic groups in the Philippines, who inhabit northern and central Palawan including the area of Mount Victoria.

Distribution and habitat:— The new species is known from a single locality in Mount Victoria, in forest habitats along a stream valley at 490–590 m elevation. Ultramafic soils are reported in the area by Robinson et al. (2009) and Chavez et al. (2015).

Phenology:— Flowers in May (based on available material).

Conservation status:— Due to its very restricted area of occupancy in proximity of a nickel mining area, C. tagbanuorum is assessed here as Vulnerable (VU D2) according to IUCN Red List Categories and Criteria ( IUCN 2012).

Notes:— Five species of Capparis were so far reported in Palawan ( Jacobs 1965), all belonging to sect. Monostichocalyx. Sect. Capparis , represented in other areas of the Philippines, in Indonesia, Australia and several islands of the Pacific ( Pelser et al. 2011 onwards; Fici 2003, 2015) by variants of C. spinosa Linnaeus (1753: 503) , has not been reported from Palawan.

Capparis tagbanuorum is readily distinguished from related species by its lorate, narrowly lanceolate or falcate leaves up to 9 times as long as wide, and by its terminal racemose inflorescence and flower features, i.e. petals 13–16 × 4–7 mm and stamens c. 78–100, with filaments (2–) 2.2–3 cm long. The new species shows some resemblance with C. callophylla Blume (1825: 53) , widespread in Indonesia and Philippines, which differs in several characters, i.e. leaves up to 3.5 times as long as wide, inflorescence a terminal panicle of subumbels, larger petals (22–35 × 6–11 mm) and stamens in lower number (c. 50–80) with longer filaments (3.5–4.5 cm). Vegetatively C. tagbanuorum can also resemble C. lanceolaris Candolle (1824: 248) , a species ranging from eastern Australia to the Philippine archipelago except Palawan, which differs from the new species in the flowers conferted towards the top of slender lateral twigs or in axillary or terminal subumbels, in the shorter sepals (6–10 mm long) and petals (8–11 mm long) and in the lower number of stamens (c. 20–40).

According to Jacobs (1965), the ratio between the length and width of the leaf blade is a fairly constant character of taxonomic value in the genus Capparis . In C. tagbanuorum this ratio is markedly higher than in other species known in Palawan. If considering other areas, within sect. Monostichocalyx leaves with length/width ratio up to 7 are reported for C. acutifolia Sweet (1830: 585) subsp. acutifolia from China, Taiwan and Vietnam. For C. divaricata Lamarck (1785: 606) from India and Ceylon, belonging to sect. Busbeckea (Endl.) Bentham & Hooker (1862: 109) , leaves up to 14 times as long as wide are recorded on sterile shoots ( Jacobs 1965). With regard to the inflorescence, in sect. Monostichocalyx more or less dense terminal racemes are reported in a few species from south-eastern Asia, e. g. C. assamica Hooker & Thomson (1872: 177) from India, Myanmar, China and Laos, C. burmanica Collett & Hemsley (1890: 19) from Myanmar, C. klossii Ridley (1920: 81) from Thailand and C. scortechinii King (1889: 394) from Malaysia and Sumatra.

The island of Palawan was rifted from the Asian mainland and never linked with other areas of the Philippine archipelago, while a land bridge connected it with Borneo for a long period during the late Pleistocene ( Voris 2000; Sathiamurthy & Voris 2006). Its present floral and faunal elements show affinities both with the Sunda shelf and the Philippine ecoregions ( Heaney 1985; Wikramanayake et al. 2001). The area of Mount Victoria is one of the less explored of Palawan, due to the lack of trails to the summit. The type locality of C. tagbanuorum coincides with that of Gynochthodes leonardii Chavez, Venturina & Alejandro (2015: 68) , a species recently described from material collected in the same Trident Mining Company concession area. Furthermore a spectacular new species of Nepenthes , N. attenboroughii Robinson, McPherson & Heinrich in Robinson et al. (2009: 196), among the largest of known pitcher plants, has been recently described from the upper elevational belt of this mountain.

Key to the species of Capparis in the Philippines *

1. Flowers solitary, axillary; one sepal of the outer pair saccate ............................................................................................ C. spinosa

- Flowers in racemes, panicles, subumbels or in supra-axillary rows; both sepals equal in each pair................................................2

2. Flowers serial in supra-axillary rows.................................................................................................................................................3

- Flowers in racemes, panicles or subumbels.......................................................................................................................................4

3. Shoots with cataphylls at base; thorns straight; gynophore 1.5–3 (3.5) cm, glabrous ............................................... C. micracantha

- Shoots without cataphylls at base; thorns recurved; gynophore 2–6.5 cm, puberulous at base ...................................... C. zeylanica

4. Leaves (4.8–) 8–9 times as long as wide; flowers in terminal racemes; stamens 78–100 ....................................... C. tagbanuorum

- Leaves up to 4.4 (–5) times as long as wide; inflorescences different; stamens up to 80..................................................................5 5. Sepals 10–14 mm long; petals 22–35 mm long; fruit 5–6.5 cm long............................................................................ C. callophylla

- Sepals up to 7 (–10) mm long; petals up to 11 mm long; fruit up to 3.5 cm long..............................................................................6

6. Young twigs glabrous, rarely puberulous; sepals 1.5–2.5 mm wide; stamens 7–9 (–12)............................................... C. floribunda

- Young twigs pubescent; sepals 2.5-6 (–7) mm wide; stamens more than 15.....................................................................................7

7. Thorns straight, 2 (–5) mm long; petals 2–4 mm long...................................................................................................... C. lobbiana

- Thorns wanting, vestigial or recurved; petals (3.5–) 4.5–11 mm long...............................................................................................8

8. Petals 7–11 mm long; gynophore 1.5–4 (–5) cm long.......................................................................................................................9

- Petals (3.5–) 4.5–7.5 mm long; gynophore (0.4–) 0.6–1.2 (–1.5) cm..............................................................................................10

9. Thorns wanting or vestigial in the Philippines; gynophore 1.5–2.5 cm, densely tomentose ......................................... C. pubiflora

- Thorns recurved, up to 7 mm long; gynophore (2–) 3–4 (–5) cm, glabrous ................................................................. C. lanceolaris

10. Petiole 2–4 (–7) mm; gynophore puberulous at base ......................................................................................................... C. sepiaria

- Petiole 5–6 (–10) mm; gynophore glabrous ................................................................................................................ C. cantoniensis

* The incompletely known C. longipes Merrill (1918: 12) was not included in the key. According to Jacobs (1965) this species, described from Luzon, probably belongs to C. pubiflora Candolle (1824: 246) .

Figures

FIGURE 1. Capparis tagbanuorum. A. Flowering branch. B. Flower. C. Pistil (part of gynophore shown). (All from the holotype, L1851396). Drawn by Silvio Fici.