Begonia tinuyopensis K.R.Mazo, L.G.Aribal, R.Bustam. & Y.P.Ang, 2021

Mazo, Kean Roe F., Aribal, Lowell G., Bustamante, Rene Alfred Anton & Ang, Yu Pin, 2021, Begonia tinuyopensis (sect. Petermannia, Begoniaceae), a new species from Zamboanga Del Norte, Philippines, Phytotaxa 516 (1), pp. 101-107 : 102-104

Begonia tinuyopensis K.R.Mazo, L.G.Aribal, R.Bustam. & Y.P.Ang sp. nov. § Petermannia ( Figs. 2 & 3 )

Type:— PHILIPPINES. Mindanao, Zamboanga Del Norte Province, municipality of Leon B . Postigo, Brgy. Tinuyop , secondary lowland forest; along the stream, 8°4’31’ N , 122°56’14’ E, 319 m asl elevation, 28 th February 2021, KRM 0004 (Holotype: PNH; Isotypes: CMUH, CAHUP) .

Diagnosis:— Begonia tinuyopensis is morphologically similar to Begonia mearnsii (section Petermannia ) in having a decumbent stem, scattered hairs over the entire plant, terminal inflorescence bearing staminate flowers with 2 tepals and pistillate flowers with 5 tepals. However, Begonia tinuyopensis is different by having sparsely pilose (vs. matted with long brown hairs) stems, ovate (vs. suborbicular to subreniform) leaves 3.8–6.4 cm × 2.5–4.5 cm (vs. ca. 10 cm × 10 cm) and glabrous (vs. densely pubescent) ovaries. A detailed comparison is enumerated in Table 1.

Herb monoecious, perennial, terrestrial. Stem decumbent, reddish to maroon, 12–15 cm tall, sparse reddish-brown pilose (ca. 5 mm long), glabrescent, internodes 1.8–2.3 cm long, rooting at lower nodes. Stipules persistent, pink to light red, ovate to triangular, 5–7 mm × 2.5–3 mm, glabrous, margin entire, apex cuspidate (1.5–2 mm long). Leaves alternate; petiole terete, 1.8–4.5 cm long, 0.8–1.9 mm in diameter, reddish-brown, hirsute; lamina basifixed, ovate, asymmetric, 3.8–6.4 cm × 2.5–4.5 cm, base obliquely cordate to rounded, apex acuminate, margin irregularly doubly-serrate to serrate, ciliate with maroon trichomes (ca. 1 mm long); 2 colour forms: one is adaxially dark green to reddish brown, lighter in colour on veins, dense red hirsute (1–1.2 mm long), abaxially light red to maroon, short hirsute on veins; another form adaxially green and abaxially pale green, vestiture pale green on both sides, lamina slightly protruding around trichomes; venation palmate, primary veins 5–6, sunken adaxially and raised abaxially, branching dichotomously. Inflorescence terminal, bisexual, protogynous; panicle 3–8 cm long, few-flowered, peduncle pinkish to dark red, glabrous to sparse puberulous 1.8–2.9 cm long; pistillate flower solitary, arising from the base of inflorescence, staminate flower distal, on short cyme branching up to ca. 3 times, producing up to ca. 5 flowers. Bracts caducous, glabrous, pinkish to white, lowest bract orbicular and ovate at the summit of inflorescence, margin entire, apex cuspidate, lowest bract ca. 4 mm in diameter. Staminate flower pedicel 3–11 mm long, white to pinkish, sparse puberulous; tepals 2, glabrous, white suffused with pink, ovate, 9–10 mm × 8–9 mm, apex rounded; androecium zygomorphic, stamens 13–15, filaments fused at base; anthers obovoid, apex retuse to truncate, dehiscing through 2 slits that run along more than half the length of anther, ca. 0.8 mm long, longer than filaments. Pistillate flower pedicel 7–10 mm long, white to pinkish, sparse puberulous; tepals 5 (rarely 4), glabrous, white suffused with pink; outer tepals widely elliptic, 10–11 mm × 7–9 mm, apex obtusely rounded; inner tepal narrowly elliptic to oblanceolate, 8–9 mm × 3–4 mm, apex rounded; styles 3, yellow, apically bifid, ca. 3 mm long, stigmas in spiral band and papillose all around. Ovary trigonous-ellipsoid, deep pink, 7–10 mm × 3–4.5 mm (wings excluded), glabrous, wings 3; wings subequal, a paler pink than the ovary, rounded triangle to ovate, truncated distally, ca. 9 mm × ca. 3 mm; locules 3, placenta bilamellate. Fruit pedicel 1–1.5 cm long, recurved when matured, 1.1–1.3 cm × 1.5–1.6 cm (wings included), wings subequal, truncated distally, obtusely-rounded proximally, dehiscing along the attachment with the wings.

Phenology:— Begonia tinuyopensis can be found flowering all year round.

Distribution and Habitat:— The new species occurs in the disturbed lowland evergreen rainforest of barangay Tinuyop, Sta. Maria and Sipacong, Leon B. Postigo, Zamboanga del Norte, Philippines. It grows in semi-shaded areas along streams and rivers, as well as trails leading to sitio Kasong and sitio Napulan at elevations between 300–400 meters above sea level. The vegetation associated with B. tinuyopensis includes species of Alocasia heterophylla (C.Presl) Merr. (1908:220) , Melastoma malabathricum L. (1753:390), Begonia oblongata Merr. (1912:310) , Saurauia longipedicellata Merr. (1922:407) , Mycetia javanica (Blume) Reinw. Ex Kort (1851:118) , Spathoglottis plicata Blume (1825:401) , and bryophytes.

Etymology:— The epithet “ tinuyopensis ” is derived from Tinuyop, a barangay of the municipality of Leon B. Postigo, Province of Zamboanga del Norte, where the type was collected.

Proposed Conservation status:— Begonia tinuyopensis is observed in two other adjacent barangays of Tinuyop, namely: barangay Sta. Maria and Sipacong. Based on our surveys, the species is estimated to have an area of occupancy (AOO) of about 16 km 2 and an extent of occurrence (EOO) of about 23.5 km 2 ( Bachman et al. 2011). Moreover, its population’s habitat is not protected and thus threatened by land conversion, human settlements and poaching. If the population is not protected and land use is not regulated, B. tinuyopensis is likely to face decline in the coming years. Therefore, following IUCN Red List guidelines, we consider B. tinuyopensis most appropriately be assigned to Endangered [EN:B1ab(i,ii)+B2ab(i,ii)] (IUCN Standards and Petitions Subcommittee, 2019).

Figures

FIGURE 2. B. tinuyopensis K.R.Mazo, L.G.Aribal, R.Bustam. & Y.P.Ang. A. Habit; B, B’. Leaf adaxial and abaxial surfaces respectively; C. Stipules; D. Bracts; E. Staminate flower face and side view; F. Stamen top view; G. Pistillate flower face view; H. Pistillate flower side view showing ovary; I. Ovary cross-section. Line drawing by YPA from KRM 0004.

FIGURE 3. B. tinuyopensis K.R.Mazo, L.G.Aribal, R.Bustam. & Y.P.Ang. A. Habitat and habit; B. Habit and habitat of green variation; C. Stipule and rooting node; D, D. Leaf adaxial and abaxial surfaces respectively; E. Leaf adaxial surface close-up, showing indumentum; F. Inflorescence; G. Inflorescence, showing bracts; H, H’. Staminate flower face and side views respectively; I. Pistillate flower face view; J. Pistillate flower side view, showing ovary; K. Ovary cross-section; L. Capsule. Photos by KR. Mazo from KRM 0004.