Amylotheca cleofei Tandang, Galindon & A.S.Rob., 2021

Tandang, Danilo N., Galindon, John Michael M., Lagunday, Noel E., Coritico, Fulgent P., Amoroso, Victor B. & Robinson, Alastair S., 2021, Amylotheca cleofei sp. nov. (Loranthaceae), a new species and genus record for the Philippines, Phytotaxa 507 (1), pp. 113-120 : 114-119

Amylotheca cleofei Tandang, Galindon & A.S.Rob. sp. nov. ( Figures 1–2 )

Diagnosis: — Amylotheca cleofei is similar to A. duthieana in having non-winged petioles, but its petioles are generally <5.8 mm long (vs. 6–25 mm long), the leaves uniformly lanceolate (vs. oblong to ovate, elliptic or lanceolate) and rounded at the base (vs. truncate, shortly cuneate or attenuate), the mature corolla buds 11.1–12.8 mm long (vs. 45–70 mm long), the corolla lobes fused just below the middle (vs. above the middle), and the anthers 1.2–1.4 mm long (vs. 2–3.5 mm long). Moreover, the pedicellate and sessile flowers of A. cleofei produce bracteoles of different shapes (vs. uniform bracteoles).

This description incorporates observations made of living material in situ on Mount. Hamiguitan, as well as from the alcohol preserved holotype and associated isotype materials. Four individuals and spirit collections of fruits and flowers were used to make representative measurements. The significant differences between the vegetative and floral parts of all Amylotheca are summarised in Table 1.

Type:— PHILIPPINES. Mindanao: Davao Oriental, San Isidro Municipality, Mount Hamiguitan Range Wildlife Sanctuary , Lowland Tropical Evergreen Rainforest , 5 August 2019, V. B . Amoroso 17680 with D. N . Tandang , 3 sheets with flowers, (holotype: PNH!; isotypes: CMUH! CAHUP!) .

Description: —Aerial stem-parasitic shrub, all stems covered with a brown-tomentum. Attachment to host through a primary haustorium, as well as multiple secondary haustoria borne on epicortical runners; runners few, 1–2.5 mm in diameter, length 3–8 cm; haustorial disk ±rounded, 3–4 mm diameter, those towards base of primary axis clustered. Stems pale when young, dark brown when mature, terete, lenticellate. Nodes flattened when young, becoming swollen when mature; internodes terete, slender, 13–31(–69.2) × 0.9–1.5(–3.2) mm. Leaves opposite to decussate, coriaceous, broadly lanceolate, 35–65(–78) mm long from petiole attachment by 16–22.8(–31.5) mm wide, adaxial surface green, glossy, abaxial surface whitish-green, dull, both surfaces glabrous, slightly curved, rounded to obtuse at base, margin entire, somewhat wavy, acute to acuminate at apex; petioles light green, terete, slender, sparsely brown-tomentose, 3.1–4.2(–5.8) × 0.7–1.8(–2.3) mm. Venation on both surfaces indistinct, midrib depressed on adaxial surface, raised on abaxial surface. Inflorescences racemose, glabrous, with decussate pairs of pedunculate dichasia in 1- to 3-flowered triads, central flower sessile, 9–12(–24) flowers in total; basal bracts brownish, 1–2, erect, cucullate, acuminate at the tip, surrounding the base of the peduncle, 1.7–2.2(–2.6) × 1.2–1.4 mm; rachis yellow green, terete, slender, 7.7–10.5(–11.4) × 0.6–0.7(–0.9) mm; internodes 2 or 3, terete, 1.5–3.8(–4.9) × 0.6–0.7(–0.9) mm; peduncles yellow green, 0.9–2.5(–2.8) × 0.7–1.3(–1.4) mm wide; peduncles of triads and single flowers yellow green, 2.8–3.9(–4.6) × 0.4–0.6(–0.8) mm, bearing 2 to 4 pairs of triads or single flowers; floral pedicels 2–2.4(–2.9) × 0.4–0.7(–0.8) mm, central flower of triad entirely sessile. Floral bracts pale yellow, those of pedicellate flowers orbicular or oblong in outline, cucullate, abaxially conduplicate along their length, rounded to acute-attenuate at apex, margin decurrent to the pedicel, appressed to the cupule, 1.1–1.8(–2) × 0.8–1(–1.5) mm; those of sessile flowers with acute to acuminate apex and longer, 1.2–2.9(–3) × 1.2–1.4(–1.7) mm. Cupule whitish-green, glossy, 0.9–1.3(–1.9) × 0.9–1.1(–1.2) mm. Calyculus pale yellow, narrow cylindrical, 0.3–0.4(–0.7) × 1.3–1.5(–1.6) mm, limb 6-merous, erect. Corolla in the mature bud yellow, light green at tip, glossy, tubular at base, 10.3–12.7(–12.8) × 2.5–3.5(–3.7) mm, obtuse at tip and gradually becoming inflated, when flattened 7.1–7.6(–8.6) mm wide. Petals 6, yellow, pale green and reflexed in the apical 1/5, narrowly triangular, fused just below the middle, 5.9–6.6(–7.1) × 1.4–1.6(–1.7) mm, tube 4.9–6(–6.5) mm long. Stamens 6, equal, opposite to and fused to the petals. Anthers 6, oblong, arranged at the same level, rounded at apex, 1.2–1.3(–1.4) × 0.2–0.4(–0.5) mm; pollen whitish. Filaments 6, adnate to corolla, pale yellow, 0.6–0.7(–0.8) × 0.4–0.5 mm. Disk pale yellow, 1–1.2(–1.3) mm wide. Style pale yellow, 7.9–10.9(–11.9) × 0.36–0.38 mm. Stigma pale green, oblong or knob-shaped, 0.3–0.4(–0.5) × 0.2–0.3(–0.4) mm. Fruits initially pale green, ripening from yellow to orange, sub-obovoid, 6.5–7.8(–8.4) × 4.8–6.6 mm. Viscin 1.4–1.7(–2) mm thick. Seeds ovoid, 5.9– 6.2(–6.7) × 2.4–2.9(–3) mm.

Key to the species of Amylotheca were cited from Barlow (1966, 1974, 1993, 1997), and Danser (1931). With the description of Amylotheca cleofei , a key to the recognised species of Amylotheca reads as follows:

1. Stems brown-tomentose, calyx lobes fused just below the middle...................................................................................... A. cleofei

1. Stems glabrous, calyx lobes fused at or above the middle ................................................................................................................2

2. Leaves variably glaucous, petiole not winged, 6–25 mm long, style articulation ≤ 0.5 mm from base, corolla in mature buds 45–70 mm long........................................................................................................................................................................... A. duthieana

2. Leaves not glaucous, petiole winged and <10 mm long ....................................................................................................................3

3. Leaves sessile or obscurely petiolate, narrowly linear to lanceolate, corolla in mature bud 27–34 mm long, anther 2–3 mm long .. .................................................................................................................................................................................... A. subumbellata

3. Leaves petiolate, lanceolate to broadly ovate or elliptic, corolla in mature bud usually> 34 mm long, anther 5–8 mm long............. ............................................................................................................................................................................................................4

4. Leaf apex mostly rounded, not acuminate, 5–14 cm long, inflorescence parts slender, peduncles of triads typically 3–10 mm long, anther up to 8 mm long................................................................................................................................................ A. dictyophleba

4. Leaf apex acuminate or acute, 12–20 cm long, inflorescence parts robust, peduncles of triads typically 1–6 mm long, anther 5–7 mm long............................................................................................................................................................. A. acuminatifolia species, adapted from Barlow (1966, 1974, 1993, 1997), Danser (1931), Nickrent et al. 2006 + and Pelser et al. 2011 +.

Distribution and ecology: — Amylotheca cleofei is endemic to Mount Hamiguitan Range Wildlife Sanctuary, San Isidro Municipality, Davao Oriental, on the island of Mindanao in the southern portion of the Philippines ( Figure 3 ). To date, the species has been recorded along a trail in an open area of tropical lowland rainforest, as well as within the forest over ultramafic rock, always in association with its host, a species of Melastoma Linnaeus (1753: 389) . No observations of flower visitors or fruit consumers have been made. However, installation of a camera trap at the site to monitor such visits to the plant is planned by the Department of Environment and Natural Resources (DENR) – Region 11.

Etymology: —The species is named after Clint Michael B. Cleofe of the (DENR) – Region 11, who discovered the plant while conducting a botanical survey with the first author.

Phenology:—The clusters of striking yellow flowers of A. cleofei were photographed and collected by the first author in August 2019. It was subsequently photographed in fruit in September 2020 and April 2021 (D.J.C. Bordios & C. M.B. Cleofe, pers. observ.).

Conservation status: —The assessment of Amylotheca cleofei satisfies the IUCN 3.1 Red List CR (Critically Endangered) Criteria B1a+2a+D ( IUCN 2012), being known from a single population at two closely situated sites within a conservation reserve where the host vegetation type has an extent of well below 100 km 2, and a total known area of occupancy of less than 10 km 2. Mature and seedling plants of the Melastoma host are common in the two areas where A. cleofei was recorded. The known Amylotheca population, all observed in either the flowering or fruiting stages, comprises 15 individuals from 5 host plants observed along the trail site in the open area of tropical lowland rainforest, and 2 individuals on a single host within the forest over ultramafic rocks. This status assessment is based on botanical inventories conducted between 2019 and 2021 at different elevations within the Mount Hamiguitan Range Wildlife Sanctuary.

Additional specimens examined (topotype): — The Philippines. Mindanao: Davao Oriental, San Isidro Municipality , Mount Hamiguitan Range Wildlife Sanctuary , Lowland Tropical Evergreen Rainforest , 31 August 2021, C. M. B. Cleofe, 001 with D. J. C. Bordios, (1 branch with fruits), ( Mount Hamiguitan Natural Science Museum ) .

Figures

FIGURE 1. Amylotheca cleofei Tandang, Galindon & A.S.Rob. A) Twig with young inflorescence. B. Single dichasium (triad). Note the sessile central flower. C) Cupule. D) Corolla tube. E) Expanded corolla) F. Corolla lobes with fused anthers and filaments. G) Pistil. H) Floral bract of sessile flower. I) Floral bract of pedicellate flower J) Seed. K) Fruit in longitudinal section. L) Fruit in cross section. Scale bars:A = 1 cm; B = 5 mm; C, H, I = 1 mm; D, E, G, J, K, L = 5.0 mm; F = 2.0 mm. Illustration: Bing Famoso Tac-an.

FIGURE 2. General morphological details of Amylotheca cleofei. A) Stems, leaves and inflorescence. B) Detail of a dichasium. Note the sessile central flower (corolla removed) of the triad. C) Detail of a single flower. D) Inflorescence with mature buds and two blooms in anthesis. E) Detail of ripe fruit. Note remains of bract of a sessile flower below centre. F) Detail of a bract subtending the peduncle (removed) of a dichasium. G) Epicortical runner appressed against the stem of its Melastoma host. Note the haustorial disk on the right side of the stem. H.) A. cleofei (foliage to left) growing on its host (central foliage), with each of its haustorial disks indicated (white arrows). Scale bars: B = 1 cm; C, E, G = 5 mm; F = 1 mm. Photographs by D.N. Tandang © 2019 (A, D, & F) and C.M.B. Cleofe © 2020 (B, C, E, G, & H).

FIGURE 3. A) Map of the Philippines. B) Map of Mindanao showing Davao Oriental. C) Map of Mount Hamiguitan Range Wildlife Sanctuary, San Isidro Municipality, Davao Oriental, showing the distribution of Amylotheca cleofei. Map generated by Tomas Reyes Jr. using ARC-GIS (2010).