Orania zheae Adorador & Fernando, 2019

Adorador, Jiro T. & Fernando, Edwino S., 2019, Orania zheae (Oranieae, Arecoideae, Arecaceae), a new species from the Philippines, with notes on another slender-stemmed species, Phytotaxa 391 (1), pp. 69-80 : 70-78

Orania zheae Adorador & Fernando , sp. nov. Type:— PHILIPPINES. Samar Province: Samar Island, Paranas, Brgy.

Tenani, 388 m, 05 February 2016, Adorador 060 & Meneses (holotype LBC!, isotype K!)

Diagnosis:— Orania zheae is distinguished from all other described Orania species by the combination of the following characters: its slender trunk and peduncle, the inflorescence which is either staminate (without complete triads, just staminate flowers) or bisexual (with complete triads), the three (out of six) epipetalous staminodes in its pistillate flowers, globose fruits which lacks prominent radial fibers in the mesocarp, and the bullet-shaped embryo.

Slender understory palm. Trunk 4 ‒ 5 m high, 6.5 ‒ 10(‒ 12) cm in diam., internodes 2 ‒ 3 cm long. Leaves 5 ‒ 10 in a crown, spirally arranged, 3.8 ‒ 4 m long including petiole, slightly arching; leaf sheath 6.7 ‒ 7.2 cm wide near the base, adaxial surface glabrous, abaxial surface with red-brown tomentum, margins disintegrating into fibers; petiole 1.3 ‒ 1.5 m × 2.5 ‒ 5 cm,. rounded below, shallowly channelled proximally then becoming rounded distally above, glabrous or with dense red-brown tomentum, wax sometimes present; rachis ca. 2.5 m long × 4 cm in middle part, rounded proximally then gradually becoming bifacial above and flat below towards the tip, glabrous or with dense red-brown tomentum, wax present; leaflets elongate-lanceolate, 26 ‒ 33 per side of the rachis, regularly arranged, held in a single plane, inserted 3.5 ‒ 6 cm apart, splitting along their costae with age, adaxial surface dull green, glabrous, with sparse wax covering, abaxial surface densely covered with dense tomentum, sparse red ‒ brown tomentum present on margins, wax present, midrib robust with 2 ‒ 4 less robust secondary costae per side, elevated abaxially; basal leaflets smallest, 31 ‒ 55 × 1.6 ‒ 2.8 cm; middle leaflets 51 ‒ 72 × 3 ‒ 5 cm, apices obliquely praemorse; apical leaflets with 2 ‒ 3-fold, 15 ‒ 32 × 1.5 ‒ 3 cm, apices concavely praemorse. Inflorescence either bisexual (with complete triad) or staminate (without complete triad), generally similar in appearance, but the bisexual type green in color, very rigid with spreading rachillae, while the staminate type, creamish white, more slender with drooping rachillae, both forms branching to 2 orders, 1.24 ‒ 1.42(‒ 1.6) m long, inflorescence axes appressed with dense-brown tomentum, ultimately disintegrating into fibrous mass with age; peduncle slender, 34 ‒ 69 × 0.8 ‒ 1.5 cm, prophyll small, ca. 15 cm long, splitting apically; peduncular bract 1.7 m × 3.4 ‒ 5 cm, thickly coriaceous, inserted 5 cm above prophyll insertion, splitting in the middle, present at anthesis, sometimes up to fruiting; rachis 73 ‒ 78 cm long, the proximal 6 ‒ 8 first-order branches further branched, the most proximal being 41 ‒ 50 cm long, rachillae bract minute; rachillae rather few, 34 ‒ 45 in whole inflorescence, 19 ‒ 55 cm × 2 ‒ 3 mm, with somewhat bulbous bases, zigzagging distally, bearing ca. 70 floral clusters, triads (in bisexual inflorescence) spirally arranged in the proximal 1/3 ‒ 1/2 part of the rachillae, the basal 1 ‒ 1.6(‒ 3) cm devoid of flowers, the triads 0.5 ‒ 1 cm apart, then bearing paired to solitary staminate flowers distally. Staminate flowers with calyx of 3 united minute sepals 1 × 1.5 mm; corolla with 3 free petals, 4 ‒ 7 × 1 ‒ 2 mm, narrowly linear-lanceolate with narrowly acute non-cucculate apices, stamens 6, filaments 1 ‒ 2 mm long, whitish (dark brown when dried), short-lageniform, anthers 3 ‒ 4 mm long, elongate-lanceolate, creamish-white (light brown when dried); pistillode absent to short pyramidal, 1 mm long. Pistillate flowers, examined only in bud (but probably near anthesis), with calyx of 3 united sepals, 3 mm wide; corolla with 3 free triangular petals, 3 ‒ 4 × 1 ‒ 2 mm; staminodes 6, 3 epipetalous, the other 3 adnate to gynoecium, subulate, flattened, without rudimentary anthers, 1 ‒ 1.5 mm long; gynoecium dark brown, trigonal, 2 × 2 mm; stigma with 3 slightly elongate lobes, 1 mm long. Fruit globose-bilobed, 3.5 ‒ 4.7 cm diam., stigmatic remains sub-basal, ripening greenish yellow; epicarp ca. 0.5 mm thick; mesocarp 2 ‒ 4 mm thick, without prominent radially oriented bony fibers; endocarp hard, brown, 1 mm thick; Seed globose, 3.4 cm diam., endosperm homogenous, white, solid inside. Embryo bullet-shaped, 6 × 2 mm, placed near the fruit summit (eccentrically apical) or lateral. Eophyll bifid. ( Figures 1 ‒ 3 ).

Habitat and Distribution: —This species is only recorded in the forested areas atop the limestone karst formations with elevations of 250– 400 m. The associated vegetation includes eurytopic tree species such as, Buchanania arborescens (Blume) Blume , Eurycoma longifolia Jack subsp. eglandulosa (Merr.) Noot. , Hopea philippinensis Dyer , Lunasia amara Blanco var. amara, Radermarchera quadripinnata (Blanco) Seem. var. pinnata and Tristaniopsis micrantha (Merr.) Peter G. Wilson & Waterhouse. The dominant shrubs comprise Ixora macrophylla Bartl. , Osmoxylon simplicifolium (Elmer) Philipson , and Tabernaemontana pandacaqui Poir. Meanwhile , climbers include Abrus precatorius L., Calamus ochrolepis (Becc.) W.J.Baker , Nepenthes samar Jebb & Cheek , and Strychnos cf. ignatii Berg. The herbaceous component consists of various species of Alocasia , Begonia, Homolomena , ferns, orchids, and bryophytes.

Its habitat preference is different from those of Orania decipiens which generally favours lowland evergreen forests and forests over ultramafic areas (authors’ personal observations). This soil-based habitat partitioning could have partially contributed to the speciation and maintenance of the two distinctive island-sympatric species as with other oceanic island palms like Howea ( Savolainen et al. 2006; Dunning et al. 2016).

This novel palm is recorded in the forests over limestone in Tenani and San Isidro in Paranas, Samar Province and San Rafael in Taft, Eastern Samar Province all on Samar Island, Philippines. Its observed habitat-preference predictably suggests wider distribution across the vegetated limestone karsts in the central portions of the island.

Uses: —This palm has limited economic importance, since the palm cabbage is known to be poisonous. The trunks are not utilized as house posts due to its slender stem as reported of other members of the genus ( Keim & Dransfield 2012; Brown & Merrill 1920). As with other species of Orania , this palm could potentially be of horticultural value.

Etymology: —The specific epithet refers to the nickname of the co-discoverer and co-collector of the type species, Ms Zhereeleen D. Meneses—‘Zhe’, a faculty member of the Environmental Biology Division, Institute of Biological Sciences, College of Arts and Sciences, University of the Philippines Los Baños. This new species is dedicated to Ms Meneses for her companionship and assistance during the fieldwork on Samar Island where she also studied orchids.

Vernacular names: — banga, banga-igang (Waray, Bisaya). The former name also applies to Orania decipiens and O. palindan , while the latter was devised by the guides during the fieldwork to refer habitat (igang = limestone, or kaigangan = forest over limestone). Thus, to avoid nomenclatural confusion, this paper formalizes ‘Zhe’s banga’ as the official common name for this new species.

Specimens examined:— PHILIPPINES. Samar Province: Samar Island, Paranas , Brgy. Tenani, 388 m, 05 February 2016, Adorador 060 & Meneses (holotype LBC!, isotype K!), Adorador 059 (LBC!, PNH!), 08 February 2016, Adorador 068 (LBC!, CAHUP!) ; Eastern Samar Province, Taft , Brgy. San Rafael, 255 m, 10 February 2016, Adorador 073 (LBC!, K!) .

Conservation status: —Critically Endangered [CR B1 b(i,ii) c(iii, iv); C1 + 2a(i)]. Orania zheae is thus far documented from three limestone karst areas, viz. (1) Tenani and (2) San Isidro, Paranas, Samar Province, and (3) San Rafael, Taft, Eastern Samar Province. Limited palm surveys in February 2016 within six 20 m × 20 m nested plots across these three sites altogether recorded just 43 palm individuals (19 mature, 12 saplings, and 12 seedlings). Surveys outside the plots in adjacent karst towers resulted to similarly low counts (usually less than 10 mature palms, each with just 2–4 seedlings).

The palm’s recorded habitat-preference to forested limestone karsts partially supports its probable wider geographic range across the interior of the island. But the observed sporadic distribution and corresponding small population size makes this palm susceptible to extinction if their limestone habitats are continually degraded or subjected to prolonged drought.

Notes: — Orania zheae is most similar to O. decipiens in its general vegetative characteristics and the sub-apically placed embryo, but is distinctive by its more slender trunk (6.5–12 cm diam. against 15 ‒ 24 cm in O. decipiens ), the much slender inflorescence and peduncle (1.5 cm diam. against 5.7 cm in O. decipiens ), its globose fruits (against subpyriform in O. decipiens ) which lacks the prominent radial fibers in the mesocarp, and the bullet-shaped embryo (against conical in O. decipiens ) ( Table 1; Figures 2 & 3 ). When these two species were compared in fresh state, differences in their mesocarp became apparent, though this fruit character is considered to be very variable and unreliable ( Keim & Dransfield 2012). Likewise, Orania zheae is apparently closely related to O. sibuyanensis (see discussions under O. sibuyanensis ).

Although naturally-occurring in the Philippines, both O. palindan and O. paraguanensis differ significantly to O. zheae because of their larger dimensions and sub-basal embryo, although similar in their globose to bilobed fruits and inflorescence with two orders of branching.

When compared to the New Guinean species, Orania zheae is most similar to O. littoralis A.P.Keim & J.Dransf. (2012: 161) and O. oreophila Essig (1980: 225) in its spirally-arranged leaves and slender peduncle (1.5 cm diam.). But both species differ from the new species in their habitat preferences, littoral to lowland forests and highland to upper montane, respectively. It also shares similarity with O. timikae A.P.Keim & J.Dransf. (2012: 155) and O. parva Essig (1980: 226) due to their diminutive trunk (4 m tall and ca. 8 ‒ 10 cm diam. in both species) and by the possession of very slender peduncle (1 cm). However, O. zheae deviates morphologically from these two species in its 2-order inflorescence branching (against 1-order) held by proportionally equal or shorter peduncle (against twice or more the length of the rachis).

Interestingly, it is unique among all the known Orania in developing both staminate (without complete triads) and bisexual (with complete triads) inflorescences. Among monoecious palms, such a condition (expressing inhibition of one sex in the triad) is, thus far, recorded in only six other palm genera, namely Lepidorrhachis (H.Wendl. & Drude) O.F. Cook (1927: 408) , Arenga Labillardiere in de Candolle (1800: 161) , Caryota Linneaus (1753: 1189) , Wettinia Poeppig in Endlicher (1837: 243), Marojejya Humbert (1955: 92) , and Elaeis Jacquin (1763: 280) (Nadot et al. 2006; Dransfield et al. 2008). Generally, at anthesis, the staminate inflorescence tends to be more slender with more drooping rachillae and creamish white in color; while the bisexual inflorescence is much more rigid with reflexed rachillae and is dark green. This flowering strategy were verified on multiple occasions; (1) remnants of persistent partially decayed staminate inflorescence were seen in individuals bearing bisexual inflorescence [Adorador 073], and (2) seedlings were observed growing at the base of individuals with staminate inflorescence [Adorador 059], thus suggesting the capacity to bear fruit via the bisexual inflorescence. Numerous studies show that this condition could be linked to environmentally regulated sex determination ( Nadot et al. 2016).

Furthermore, it is noteworthy that O. zheae is distinctive by the possession of six subulate staminodes with 3 being epipetalous, and the other 3 adnate to the gynoecium. Although only pistillate flower buds [probably near anthesis] were studied and perhaps still undergoing development, the adnation of the developing staminodes to the petals consistently remained prominent. This particular staminode adnation dimorphism is yet unreported in Orania ( Keim & Dransfield 2012) . This observation could stir up further insights in palm androecium evolution, development, and significance (see Nadot et al. 2011).

Local guides identified wild pigeons ( Ducula sp. and Ptilinopus sp. ), hornbills ( Penelopides sp. ) and wild boars (Sus sp.) as fruit and seed dispersers of this palm, though only the latter appears capable of consuming large fruits. Interestingly, during a survey on July 2016, JTA spotted a Philippine flying lemur ( Cynocephalus volans ) around the vicinity of a fruiting population of Orania zheae — though it was not observed to actually eat the globose yellowish fruits. During anthesis, the inflorescences were observed to be visited by various species of beetles and flies.

Orania sibuyanensis (Becc.) Adorador & Fernando , comb. et stat. nov. Orania philippinensis Scheff. ex Becc. var. sibuyanensis Beccari (1919: 332) . Orania palindan (Blanco) Merr. var. sibuyanensis (Becc.) Merrill (1925: 161) , synon. nov. Type:— PHILIPPINES, Romblon Province, Sibuyan Island, Magallanes (=Magdiwang), Mt. Guiting-guiting, March 1910, A.D.E. Elmer 12066 (holotype FI! [FI014133; isotypes GH [00035149], L! [L0059815], U! [U149821], US! [ US 00087601]).

Slender understory tree palm. Trunk 4 m high, ca. 7–12 cm diam., internodes 1.5 cm long. Leaves ca. 5–8 in crown, to 3 m long including petiole; leaf sheath 8.3–12.7 cm near the base, adaxial surface glabrous, abaxial surface with red-brown tomentum; petiole 1.3 m × 2.5–3, channelled proximally then becoming rounded distally above, with dense red-brown tomentum; rachis ca. 1.7 m × 2.5 cm, rounded proximally then gradually becoming bifacial above and flat below on the distal portions, with dense red-brown tomentum; leaflets elongate-lanceolate, ca. 35 on each side of the rachis, regularly arranged, held in a single plane, spaced at 3.5–5 cm apart, regularly arranged, held in a single plane, adaxial surface dull green, glabrous, with sparse wax covering, abaxial surface densely covered with dense tomentum, midrib robust with 2 ‒ 3 less robust secondary costae per side, elevated abaxially; basal leaflets smallest, ca. 3 cm wide; middle leaflets ca. 60 ‒ 69 × 4 ‒ 5 cm, apices obliquely praemorse; apical leaflets 2 ‒ 3-fold, 18 × 2 cm, apices praemorse. Inflorescence bisexual, branching to 2 orders, somewhat drooping, 0.9–1.18 m long, inflorescence axes creamy white, glabrous or appressed with sparse ‒ brown tomentum; peduncle slender, 45–50 × 0.7–1.2 cm, prophyll 37 × 6 cm, apically splitting; peduncular bract thickly coriaceous, 1.42–1.52 m × 3 ‒ 5(–7.6) cm, splitting in the middle, persistent an anthesis; rachis 68 cm long, the proximal ca. 12 first-order branches further branched, the most proximal branch 40 cm long, rachillae bract minute; rachillae rather few, ca. 44 in whole inflorescence, ca. 25–40 cm × 2 ‒ 3 mm, with somewhat bulbous bases, zigzagging distally, bearing ca. 70 floral clusters, triads spirally arranged in the proximal 1/3 ‒ 1/2 part of the rachillae, the basal 1 ‒ 3 cm devoid of flowers, the triads 0.5 ‒ 1.5 cm distant, then bearing distichous to solitary staminate flowers distally. Staminate flowers with calyx of 3 united minute sepals, 1 × 1 mm; corolla with 3 free spathulate petals (specially in the distal portions of the rachillae, very rarely broad lanceolate) 5 × 2 mm, with short-acute cucculate apices, stamens 6, filaments linear, 1 mm long, dark brown, anthers elongate-lanceolate, 3 ‒ 4mm long, light brown when dried; pistillode absent. Pistillate flowers examined only in bud, with calyx of 3 united sepals, 1 × 3 mm wide; corolla with 3 free triangular petals, 3 × 3 mm; staminodes 6, ca. 1 mm long, subulate, adnate at the base of gynoecium; gynoecium dark brown, trigonal, 2 × 2 mm; stigma with 3 short lobes. Fruit globose, 6 ‒ 6.5 cm diam., ripening yellow, mesocarp 3.5 ‒ 4 mm thick; Seed globose, c. 5 cm diam., endosperm homogenous. Embryo not known. Eophyll not known.

Habitat and Distribution: —Only known from four collections from the forests over ultramafic areas (up to ca. 600 m elevation) of Mt. Guiting-guiting, Sibuyan Island, Romblon, Philippines.

Uses:— Not known, but could potentially be of horticultural value.

Etymology: —The epithet refers to the Island of Sibuyan, Romblon Province, Philippines.

Vernacular Names:— banga (Bisaya)

Specimens examined: — PHILIPPINES, Romblon Province: Sibuyan Island, Magallanes (= Magdiwang ), Mt. Guiting-guiting , April 1910, A.D.E. Elmer 12066 (holotype FI! [FI014133; isotypes GH [00035149], L! [L0059815], U! [ U149821 ], US! [ US 00087601]) ; May 1972, E.G. Reynoso & R. Espiritu 134 (PNH!); on the northern slope, 21 May 1987, E.S. Fernando 696 (LBC!); Barrio Hawasan , 26 May 1992, B.C. Stone et al. PPI 6708 (K! [K000667879]) .

Conservation status:— Critically endangered [CR B1 b(iii, iv) c(iii)]. Despite its habitat being legally protected (within the 152.6 km 2 Mt. Guiting-guiting Natural Park [MGNP]), continuing anthropogenic disturbances such as unregulated harvesting of non-wood forest products and agricultural land conversions pose significant threats to the remaining populations of O. sibuyanensis . The species-level recognition of this taxon elevates its evolutionary significance—subsequently its conservation value, being only found in the lowland (<600 m elevation) ultramafic areas of MGNP in Sibuyan Island.

Notes: —The species-level recognition of Orania sibuyanensis and its segregation from O. palindan sensu Keim & Dransfield (2012) is consistent with the current morphological species concept of the genus. This taxonomic inference only became apparent upon careful examination of complete herbarium materials (see Specimens examined) collected from the type locality which concur with the description in the protologue [as Orania philippinensis Scheff. ex Becc. var. sibuyanensis Becc. ] and are undoubtedly referable to the type material (Elmer 12066). O. sibuyanensis is only similar to O. palindan in having a relatively large globose fruit (c. 6.5 cm across) with rather thick mesocarp (3.5–4 mm), but it is decidedly different in the proportionately smaller habit (5 m tall and 7–12 cm stem diam. against 20–30 m tall and 15–40 cm stem diam. in O. palindan ), diminutive peduncular bract (5 cm wide against 14 cm in O. palindan ) and inflorescence borne on a very slender peduncle (0.7–1.2 cm diam. against 7–8.7 cm in O. palindan ). Moreover, the petals of the staminate flowers [at least in the terminal portions of the rachillae] of O. sibuyanensis are spathulate with short-acute cucullate apices while that of the typical O. palindan is linear-lanceolate with narrowly acute non-cucculate tips ( Figure 4 ). The observed peculiar petal form in O. sibuyanensis could be due to the mechanical constriction of the developing inflorescence before exsertion due to the narrower peduncular bract.

Orania sibuyanensis is apparently most closely related to O. zheae based on its general vegetative characteristics, the inflorescence borne on a slender peduncle and the yellowish globose fruits. However, O. sibuyanensis is distinctive by its habitat preference (forests over ultramafic rocks against forests over limestone for O. zheae ), bisexual inflorescences (against either bisexual or staminate in O. zheae ), spathulate petals with short-acute cucullate apices of the staminate flower (linear-lanceolate with narrowly acute tips in O. zheae ), and absence of epipetalous staminodes in pistillate flowers (present in O. zheae ).

Furthermore, Orania sibuyanensis is also comparable to O. decipiens in its general vegetative characteristics, but is distinctive by its more slender trunk (7–12 cm diam. against 15 ‒ 24 cm in O. decipiens ), the much slender inflorescence and peduncle (1.5 cm diam. against 5.7 cm in O. decipiens ), the characteristic petal of staminate flowers, and its globose fruits (against subpyriform in O. decipiens ).

Similar to morphological comparisons with Orania zheae (see discussions under O. zheae ), O. sibuyanensis likewise shares affinity with four slender New Guinean species, viz. O. littoralis , O. oreophila , O. timikae , and O. parva . Although additional characters such as embryo position and eophyll form are currently unknown for this species, the enumerated morphological evidences are taxonomically significant to merit its species-level status.

Figures

FIGURE 1. Orania zheae Adorador & Fernando. A Slender habit in fruiting stage. B Leaf sheath and petiolar base covered with dense redbrown indumentum with dried bisexual inflorescence.C Adaxial view of the leaf showing the white indumentum.D Pistillate inflorescence with more rigid rachillae. E Staminate inflorescence with drooping rachillae. F Immature triads of the bisexual inflorescence. G Male flowers at anthesis of staminate inflorescence. A was taken from the holotype (Adorador 060 & Meneses); B from a palm atop karst formation in San Isidro, Paranas, Samar Province, Samar Island; C, E, and G from Adorador 059; D and F from Adorador 068. Scale bar = 1 cm. Photos: A–G (Jiro T. Adorador).

FIGURE 2. Orania zheae Adorador & Fernando. A Dried male and female flowers of the bisexual inflorescence. B Female flower with a petal removed to expose the gynoecium with two visible adnate subulate alternipetalous staminodes (indicated by white arrow). C Petals of the female flower showing the subulate epipetalous staminodes (indicated by white arrow). D Ripe globose fruits. E Seedling leaf. F Whole fruit comparison of O. zheae (below) with O. decipiens (above). G Dissected fruit comparison of O. zheae (above) with O. decipiens (below) showing differences in their mesocarp. H Close-up comparisons of embryo shape between O. zheae (left) and O. decipiens (right), also showing with the prominent radial fibers in the mesocarp of the latter (indicated by white arrow). A‒C were taken from Adorador 068; D, F‒H (in part) from the holotype (Adorador 060 & Meneses); F‒H (in part) from Adorador 066 (Orania decipiens). Photos: A‒H (Jiro T. Adorador).

FIGURE 3. Orania zheae Adorador & Fernando. A Middle leaflets. B Apical leaflets. C Portion of the inflorescence. D Triads on rachillae. E Staminate flower in bud. F Staminate flower at anthesis (top-side view). G Petal of pistillate flower showing epipetalous staminode (adaxial side). H Gynoecium, petals removed. I Mature fruit. J Fruit in longitudinal section showing sub-apical embryo. A‒C from Adorador 060 & Meneses, D‒H from Adorador 068, I‒J from Adorador 059. Scale bar: A = 5 cm, B‒C = 7 cm, D = 7 mm, E‒F = 4 mm, G = 3 mm, H = 2 mm, I‒J = 3 cm. Drawn by Jiro T. Adorador.

FIGURE 4. Comparison of Orania sibuyanensis (Becc.) Adorador & Fernando and Orania palindan (Blanco) Merr. A Slender peduncular bract of O. sibuyanensis B Diminutive inflorescence borne on slender peduncle with persistent prophyll and peduncular bract of O. sibuyanensis. C Fragments of robust inflorescence of O. palindan. D-E Staminate and pistillate flowers of O. sibuyanensis. F Staminate and pistillate flowers of O. palindan. A & D were taken from the holotype, A.D.E. Elmer 12066 (photo-type Fl!); B & E were taken from E.S. Fernando 696 (LBC!); C & F from H.E. Moore 9395 & J.V. Pancho (CAHUP!). Scale bar: D = 1 cm. Photos: A & D retrieved from http://plants.jstor.org/stable/10.5555/al.ap.specimen.fi014133; B‒C & E‒F (Jiro T.Adorador).