Amyema lisae Pelser & Barcelona, 2018

Pelser, Pieter B., Olimpos, Shiella Mae B., O’Byrne, Peter & Barcelona, Julie F., 2018, A new species of Amyema (Loranthaceae) and a new Gastrodia (Orchidaceae) record for the Philippines from Negros Island, Phytotaxa 371 (1), pp. 25-32 : 27-30

Amyema lisae Pelser & Barcelona , sp. nov. ( Fig. 1 )

Type:— PHILIPPINES. Negros: Negros Oriental Province, Cuernos Mountains, Balinsasayao - Twin Lakes Natural Park, Municipality Sibulan, Barangay Enrique Villanueva, loco dicto Mt Kalbasaan, 9° 21’ 42.5” S, 123° 10’ 36.4” E, ca. 1045 m, 25 November 2017, Barcelona et al. 4459 (holotype PNH!, isotypes CEBU!, CAHUP!).

Diagnosis: — Amyema lisae is unique among all other described Amyema species in having relatively small leaves (lamina up to 10 cm long) in whorls of 4–7 and pedunculate, simple umbels with 6 or 9 tomentose 5-merous flowers.

Description: —Climbing hemi-parasitic epiphyte with epicortical runners; glabrous except for inflorescences and flowers. Internodes terete, dilated at the nodes, 4–12 cm long, ca. 3 mm wide and smooth when bearing mature leaves, ca. 7 mm wide and coarsely and irregularly ridged when older, light or reddish-brown. Leaves verticillate, in whorls of 4–7; petioles terete but slightly channelled at apex, 8–17 mm long, light green; laminae flat, bifacial, narrowly elliptic to elliptic, (3.5–)7–9(–10) cm long, (1–)2(–2.8) cm wide, length/width ratio 3–6, base narrowly cuneate, margin entire and not recurved, apex acuminate, midrib raised only on the abaxial leaf surface, secondary venation pinnate and indistinct, coriaceous, adaxial surface green and shiny, abaxial surface paler and dull. Inflorescences axillary on leafless nodes or emerging from internodes or epicortical runners, simple umbels of 6 or 9 flowers, tomentose; peduncles 3–6 mm long, pale green, tinged pinkish at base and apex; bracts absent. Flowers 5-merous, 2.7–3.7 cm long, tomentose; pedicels 1.5–2 mm long, slightly swollen and articulated at apex, light green or pinkish; bracteoles appressed to hypanthium, narrowly triangular, ca. 1 mm long, light green or pinkish; hypanthium funnel-shaped, 2–3 mm long, 1.5–2 mm wide at apex, calyx lobes ca. 0.25 mm long, light green, slightly pinkish at apex; corolla in mature buds (2–) 2.5–3.5 cm long; corolla tube 1.7–2.8 cm long, splitting open all the way to the base after anthesis, adaxially glabrous, orange yellow becoming pale green towards the lobes; corolla lobes narrowly triangular, 6–9 mm long, 1–1.5 mm wide, adaxially glabrous, light green; stamens epipetalous, light green, free parts of filaments 3–3.5 mm long and glabrous, anthers 2.5–3 mm long, pollen whitish grading to cream; style 2.5–3.2 cm long, exerting 6–7 mm from the corolla tube, glabrous, light green. Fruits unknown.

Diagnostic characters: — Amyema lisae is one of only four known Amyema species that have verticillate leaves (i.e. more than two leaves per node) in combination with pedunculate simple umbels. The other three species that have this character state combination are A. fasciculata (Blume 1826: 661) Danser (1929: 295) from the Philippines, Indonesia, and New Guinea, A. polillensis ( Robinson 1911: 200) Danser (1929: 298) from the Philippines, and A. umbellata Danser (1931: 352) from the Moluccas ( Barlow 1997). Amyema lisae is, however, unique among these four species in having inflorescences and flowers that are entirely covered with a dense tomentose indumentum that persists when the flowers are mature. In contrast, the corolla of the other species is either glabrous ( A. fasciculata , A. polillensis , A. umbellata ) or tomentose only when young ( A. fasciculata ). In addition, A. lisae shows differences with these three Amyema species in several other characters, as outlined below and in Table 1.

This new species generally has more leaves per node than A. fasciculata (4–7 vs. 2–4) and they are usually narrower (length/width ratio 3–6 vs. 2–3(–7.5)). In addition, our new species has larger flowers ( Table 1). For example, in mature flower buds, the corollas of A. lisae measure 2–3.5 cm, whereas those of A. fasciculata are 1.4–2 cm long, although Danser (1935) mentions a single A. fasciculata specimen with much larger flowers (corolla in mature flower bud 2.8 cm long; Velasco 24118 at M, specimen not seen). Amyema lisae also differs from A. fasciculata in having more flowers per inflorescence (6 or 9 vs. 2–4). Furthermore, A. fasciculata might have a different inflorescence type than this new species. Danser (1931) noted that A. fasciculata only seemingly has simple umbels and that the inflorescence of this species might actually be an umbel composed of two dyads. He based this hypothesis on the presence of two bracts at the apex of the peduncle and the occasional presence of umbels with two rays with bracts at their apices (instead of at the apex of the peduncle). In contrast, A. lisae lacks bracts at the apex of the peduncle and our specimen does not have dyads or triads of flowers united in rays within the umbellate inflorescences.

Amyema lisae is perhaps most similar to A. polillensis , which also has 4–7 leaves per node and yellow flowers. In addition to its conspicuous inflorescence and flower indumentum, this species can, however, readily be distinguished from A. polillensis by its shorter peduncle (3–6 vs. 7–14 mm) and pedicels (1.5–2 vs. 3–5 mm), and by its usually smaller leaf lamina (3.5–10 × 1–2.8 vs. 8–17 × 2.5–7 cm), which is narrower than that of A. polillensis (length/width ratio 3–6 vs. 2–3; Table 1).

*The lectotype at US (McGregor BS 10384, photo!) is 4-merous ( Barlow 1992, 1997), but Robinson (1911) and Danser (1935) list this species as being 5-merous.

Amyema umbellata is only known from the type specimen (Toxopeus 215, BO), which is presumably lost ( Barlow 1992). This species differs from A. lisae in having umbels with up to 12 flowers (vs. 6 or 9) that have longer pedicels (ca. 2.5 vs. 1.5–2 mm). Furthermore, it has larger leaves (lamina 10–16 × 2.5–4.5 vs. 3.5–10 × 1–2.8 cm) that are either opposite or in whorls of 3 or 4 (vs. 4–7) and that have distinct (vs. indistinct) secondary venation ( Table 1).

In addition to A. fasciculata , A. polillensis , and A. umbellata , also A. beccarii (Van Tieghem 1894: 506) Danser (1929: 294) , A. seemeniana (Schumann in Schumann & Hollrung 1889: 106) Danser (1929: 299), and A. squarrosa ( Krause 1922: 485) Danser (1929: 299) have flowers in simple umbels, but these species do not have a verticillate leaf arrangement. Amyema wenzelii ( Merrill 1913: 370) Danser (1929: 299) has leaves in whorls but can be distinguished from A. lisae by its sessile instead of pedunculate umbels.

Distribution and habitat: —Only known from the type locality in the Balinsasayao - Twin Lakes Natural Park (Negros Oriental Province, Cuernos Mountains) in mid-elevation tropical rain forest.

Conservation status: — Amyema lisae is only known from a single plant. It is presently unclear if it is a locally common or rare species. We therefore consider its conservation status Data Deficient (DD; IUCN 2017).

Etymology: —We name this species after Lisa J. Paguntalan, Executive Director of the Philippines Biodiversity Conservation Foundation, Inc. to honor her contributions to nature conservation in the Philippines. Ms. Paguntalan has been an epitome of a conservationist who is most successful in bringing together stakeholders in the conservation of biodiversity. She is a champion of organizing and involving local communities in conservation programs in many parts of the country.

Gastrodia sabahensis : — Gastrodia is a widespread genus of perhaps as many as 90 species of holomycoheterotrophic terrestrial orchids ( Aung & Jin 2018). Prior to our discovery, three species of Gastrodia were known from the Philippines ( Pelser et al. 2016): the recently described G. cajanoae Barcelona & Pelser in Pelser et al. (2016: 53), G. javanica ( Blume 1825: 421) Lindley (1840: 384) , and G. verrucosa Blume (1856: 175) . Gastrodia cajanoae is endemic to the Philippines, whereas the other two species are widespread in northern Malesia and southern East Asia, with G. verrucosa only recently reported for the Philippines ( Barcelona et al. 2013). The Gastrodia plants collected in BTLNP (Barcelona et al. 4456!, 4467! & 4473!, CEBU) and during subsequent fieldwork in Northern Negros Natural Park (NNNP) in Negros Occidental Prov. (Barcelona et al. 4477!, 4478! & 4485!, PNH) belong to the G. verrucosa complex. Together with the majority of S.E. Asian Gastrodia , this group belongs to section Codonanthus ( Schlechter 1911) on account of having sepals and petals partly-fused into a perianth tube. Many species in this group (including G. sabahensis ) are known to have pedicels that notably elongate when plants are fruiting ( Chung & Hsu 2006). At present, however, species delimitation within this group is not entirely satisfactory. The G. verrucosa complex contains several morphologically similar species that are poorly understood and some of these may not be taxonomically distinct at the species level ( Tuyama 1982, Suddee & Harwood 2009). This complex includes G. boninensis Tuyama (1939: 2) , G. confusa Honda & Tuyama (1939: 659) , G. confusoides Hsu, Chung & Kuo (2012: 273) , G. holttumii Carr (1929: 38) , G. maliauensis Suetsugu, Suleiman & Tsukaya (2018: 78) , G. sabahensis Wood & Lamb in Wood (2008: 139), G. shimizuana Tuyama (1982: 380) , and G. verrucosa . The Negros plants ( Figs. 2 & 3 ) most closely resemble G. sabahensis from Borneo (Sabah), and we here tentatively identify them as this species, although they have larger flowers (calyx 21–24 vs. 15–17 mm long) than previously reported ( Wood 2008). They also show some minor differences in the shape of the column, which appears to be slightly broader at the base and has rather broad stelidia with quite blunt apices ( Fig. 3 ) when compared with illustrations in the protologue of G. sabahensis ( Wood 2008) . Column features have been considered important diagnostic characters for distinguishing species within the G. verrucosa complex ( Hsu et al. 2012, Suetsugu et al. 2018). However, because of the current lack of consensus among Gastrodia taxonomists about the species delimitation within the complex and therefore what morphological characters are of taxonomic significance at the interspecific level, we prefer to take a conservative view and refrain from describing the Negros Gastrodia as a new species or subspecies.

The Negros plants were found on volcanic soils among leaf litter in humid closed-canopy mid-elevation tropical forest and were found sympatric with G. cajanoae at one site in BTLNP.

Figures

FIGURE 1. A–I. Amyema lisae. A. Inflorescences. B. Front view of 5-merous flowers. C. Simple umbel of tomentose flowers. D. Inflorescence with scale. E. Stamens and style. F. Verticillate phyllotaxy. G. Adaxial view of leaf. H. Abaxial view of leaf. Barcelona et al. 4459. Photographs by P.B. Pelser & J.F. Barcelona, additional photos are available from the PhytoImages website (Nickrent et al. 2006 onwards).

FIGURE 2. A–I. Gastrodia sabahensis. A. Habit of flowering plant. B. Plant in fruit, showing pedicel elongated to ca. 13 cm. C. Inflorescence. D. Flower in side view. E. Flower in front view. F. Dehiscing fruit. G. Abaxial view of flower. H. Longitudinal section of flower. A, C, D, G, H: Barcelona et al. 4456. B, E: Barcelona et al. 4477. F: Barcelona et al. 4485. Photographs by P.B. Pelser & J.F. Barcelona, additional photos are available from the PhytoImages website (Nickrent et al. 2006 onwards).

FIGURE 3. A–E. Gastrodia sabahensis. A-C: Column.A.Abaxial view. B. Side view. C.Adaxial view. D–E: Labellum. D.Abaxial view. E. Adaxial view.A–C: Barcelona et al. 4456. D, E: Barcelona et al. 4477. Photographs by P.B. Pelser & J.F. Barcelona.