Balanophora coralliformis Barcelona, Tandang & Pelser

Pelser, Pieter B., Tandang, Danilo N. & Barcelona, Julie F., 2014, Balanophora coralliformis (Balanophoraceae), a new species from Mt. Mingan, Luzon, Philippines, Phytotaxa 170, pp. 291-295 : 291-295

Balanophora coralliformis Barcelona, Tandang & Pelser , sp. nov. ( Figs. 1 & 2)

Type: — PHILIPPINES. Luzon: Aurora Province, San Luis Municipality, Mt. Mingan , beside trail en route to summit, 15°27’48.8” N, 121°23’43.3” E, c. 1725 m, 23 February 2014, Barcelona 3895 with Pelser & Tandang (staminate plant; holotype: PNH, isotypes: CHR, K, PUH, US) .

Balanophora coralliformis differs from all other described Balanophora species in the coral-like growth of repeatedly branched aboveground tubers.

Herbaceous, holoparasitic, dioecious, clump-forming, up to c. 30 cm tall above ground. Tubers predominantly above ground, repeatedly branched at angles of 40–50 degrees; tuber segments elongated, cylindrical, up to c. 5 cm long, 0.5–1.2 cm diam., widening at apex of fertile terminal segments, basal and internal segments dark brown, terminal segments lighter brown towards apex, surface coarse and covered with scattered cream to light brown stellate warts composed of 3–8 globose clusters of cells. Stems individually emerging from apex of terminal tuber segments. Leaves in 2 opposite, decussate pairs, occasionally with an additional single leaf, imbricate, all inserted at nearly the same level, obovate to broadly obovate, spathulate, concave, on the same tuber of nearly the same size, 2.4–2.7 by 1.1– 2 cm, base attenuate, margin entire, apex rounded, patent at anthesis, yellow to straw-colored. Inflorescences emerging endogenously from the apex of the tuber segments. Staminate inflorescence terminal, racemose, 3–4 cm by 1.5–2.5 cm; peduncle 0.6– 1 cm long; bracts c. 1 mm, truncate; yellow to straw-colored. Staminate flowers 12–16, spirally arranged in conspicuous vertical rows, bisymmetric on account of lateral elongation, 4-merous, pedicels 2–4 mm, tepals recurved at anthesis; median tepals 2, 3–4 mm by 2–3 mm, apex truncate or rounded; lateral tepals 2, 3–4 mm by c. 1.5 mm, apex acute; sterile part of synandrium 1–2 mm; fertile part of synandrium ellipsoid, laterally elongated, 1.5– 2 mm long, anterior-posterior width c. 1.5– 2 mm, lateral width 2–4 mm; anther cells parallel, running from base to apex of fertile part of synandrium, longitudinally opening, white. Young pistillate inflorescence terminal, spicate, ellipsoid, 1.3–1.6 by 0.9–1.2 cm, peduncle 3–4 mm long, yellow to straw-colored; spadicles (narrowly) obovoid, 0.4– 0.5 by 0.15– 0.3 mm, apex rounded. Pistillate flowers numerous, minute, largest ones c. 1.5 mm. Fruits not observed.

Distribution and habitat: —Only known from the type locality between 1465 and 1725 m on the SW slopes of Mt. Mingan, in montane mossy forest. Some populations are sympatric with B. papuana .

Conservation status: —This species is only known from few (<50) plants at the type locality and has not been found in other areas with similar habitats in the remaining montane forests of Nueva Ecija and Aurora provinces. However, this may be due to the lack of botanical explorations in these adjacent areas. Mt. Mingan is not currently included in the country’s Protected Areas by the Department of the Environment and Natural Resources ( DENR). As such, the habitat of B. coralliformis is under significant threat by activities such as illegal logging and slash-and-burn agriculture. Therefore, we consider this species to be Critically Endangered, CR B1ab(iii,iv); D ( IUCN 2001).

The presence of other threatened species such as Rafflesia lagascae Blanco (1845: 595) and Philippine Eagle ( Pithecophaga jefferyi ) on the lower slopes of Mt. Mingan further indicates the need to establish Mt. Mingan as a Protected Area.

Etymology: —Named for the coral-like appearance of its above-ground tubers.

Additional specimens examined (paratypes): — PHILIPPINES. Luzon: Aurora Province, San Luis Municipality, Mt. Mingan , beside trail, en route to summit: Barcelona 3889 (staminate plant, CAHUP), 3890 (pistillate plant, CHR, K, PNH, PUH), 3891 (pistillate plant, US), 3892 (CAHUP) with Pelser & Tandang .

Diagnostic characters: — Balanophora coralliformis is easily recognized by its repeatedly branching aboveground tuber segments and their coarse texture reminiscent of a branching stony coral colony. Compared with other Balanophora species, most of the tuber mass of B. coralliformis is above ground and none of the other species shows a similarly high degree of branching into elongated cylindrical segments.

Although quite different from B. papuana in some characters [e.g. branching of tubers and color of inflorescences (yellow to straw-colored vs. light yellow, orange, or red); Figs. 1 & 2], B. coralliformis most closely resembles this species, particularly in its reproductive morphology ( Figs. 1 & 2), and keys to it in Hansen’s (1972) identification key. Balanophora coralliformis and B. papuana are both dioecious, have patent leaves in two closely set decussate pairs (although some B. papuana specimens have three or occasionally up to five pairs of leaves and some B. coralliformis have an additional single leaf) that are of similar size on the same tuber. In addition, the staminate flowers of both species are placed in conspicuous vertical rows, shortly pedicellate, and composed of two median tepals that are wider than the two lateral, acute tepals. Furthermore, B. coralliformis and B. papuana both have a laterally elongated synandrium with long anther cells that reach from the base to the apex of the fertile part of the synandrium (Hansen 1976). Despite the close resemblance between these two species in reproductive morphology, they maintain their distinct vegetative differences in sympatry, as we observed on Mt. Mingan ( Figs. 1 & 2).

The tubers of B. coralliformis resemble, to some degree, those of B. elongata Blume (1827: 87) var. elongata from Java and Sumatra (Hansen 1972) and Peninsular Malaysia [Hambali 1980, as B. hansenii Hambali (1980: 425)]. These are also elongated and cylindrical. However, the tubers of B. elongata var. elongata are much less frequently branched above ground. In addition, this taxon differs markedly from B. coralliformis in other characters, such as the spiral (as opposed to decussate) leaf arrangement and flowering inflorescences that are partially or entirely covered by the upper leaves (Hansen 1972) instead of being fully exposed (at least in staminate plants; Figs. 1 & 2).

Also the poorly known B. fungosa J.R. Forster & G. Forster (1775: 99) ssp. indica (Arnott 1838: 37) Hansen (1972: 100) var. minor (Eichler in De Candolle 1873: 145) Hansen (1972: 106) from south India, Sri Lanka, and Thailand (Hansen 1972, Nickrent 1997 onwards, Su et al. 2012) is described as having elongated, cylindrical tuber segments (Hansen 1972, Su et al. 2012), but photos on the Parasitic Plant Connection website (Nickrent 1997 onwards) suggest that these are subterranean. Furthermore, amongst others, the leaves of this variety are more numerous (15–35 vs. 4 or 5) and spirally arranged (vs. opposite), and the staminate flowers are actinomorphic (vs. bisymmetric).