Amorphophallus calcicolus M.N.Tamayo, Magtoto & Sumalinog, 2021

Tamayo, Maverick N., Magtoto, Liezel M., Sumalinog, Melchor S., Reyes, Tomas D. & Austria, Celia M., 2021, Amorphophallus calcicolus (Thomsonieae, Araceae), a new species from the Bohol island, Central Visayas, Philippines, Phytotaxa 489 (2), pp. 229-235 : 230-234

Amorphophallus calcicolus M.N.Tamayo, Magtoto & Sumalinog , sp. nov. ( Figs. 2 & 3 )

Amorphophallus calcicolus closely resembles A. longispathaceus by the peduncle much longer than the spathe; the spathe almost as broad as long, and the spadix at most twice as long as the spathe but distinct in having shorter leaves, smaller male zone, depressed diskshaped ovary, longer styles, ovoid or irregularly shaped warts inside the spathe base, and shallowly 2–3-lobed stigma. A comparison between the two species is presented in Fig. 4 .

Type: — PHILIPPINES. Central Visayas, Bohol island (province), Municipality of Bilar, Loboc Watershed Forest Reserve ( LWFR) (forest over karst), 250–260 m elevation, 19 July 2020, M . N . Tamayo 0224 with M . Sumalinog, Jr. (holotype PNH!, isotypes NLUH!, PUH!) .

Tuber depressed globose, 5–7 cm diameter, 4–5 cm high. Leaf solitary. Petiole ca. up to 1 m × 1.0– 2.5 cm; background color dirty white, pale to deep green or light maroon; sometimes darker in the middle and paler near the inflorescence and tuber; markings elongate-elliptic to circular whitish or reddish spots, with scattered smaller and raised whitish spots giving a bumpy texture. Rachis winged distally from the basal branching; basal part naked with a few petiolate leaflets. Leaflets elliptic-lanceolate to broadly-elliptic, 4.0– 12.5 cm × 3.0– 4.5 cm, margin undulate, long acuminate (acumen 3.0– 3.5 cm long); lateral veins 9–15 pairs, adaxially sunken. Inflorescence solitary, long peduncled; peduncle almost the same coloration and marking with petiole, 48–75 cm × 0.5–1.5 cm; spathe campanulate, 9–17 cm × 7.5–12.0 cm, widely triangular (when spread), acute or obtuse, margin undulate, smooth, membranaceous, base strongly convolute, limb broad and arching over; outside of spathe maroon near edges turning brown with scattered white spots towards limb; limb whitish; inside of spathe dark maroon to reddish near margin, dirty white and densely clothed with ovoid or irregularly shaped warts towards the base. Spadix sessile, at most twice as long as the spathe, 16–30 cm × 0.8–1.5 cm. Appendix elongate conic, 11.7–24.5 cm × 0.8–1.5 cm, gradually tapering upward, top blunted; more or less constricted near the male zone; relatively smooth to finely rugose when fresh; reddish or purplish. Female zone cylindric, 2.0–3.0cm × 1.0–2.0 cm, flowers slightly distant. Ovaries depressed disk-shaped, 2.0–3.0 mm × 2.0–3.0 mm, unilocular, generally white with a tint of red on tips. Style maroon or brown, 5.0–8.0 mm × 1.0– 1.2 mm. Stigma yellowish, 0.9–1.5 mm × 1.2–2.0 mm, shallowly 2–3-lobed, lobes rounded or conic, surface minutely papillate. Male zone elongate obconic or cylindrical, 1.7–2.5 cm × 0.5–1.2 cm, with congested flowers. Male flowers white to pinkish, consisting of 2–3 stamens. Stamens white to pale yellow, 1.5–1.8 mm long. Filaments 1.0– 1.2 mm long, connate. Anthers 2.0 mm × 1.0– 1.5 mm, rounded, pores apical, elongate. Fruits not observed.

Distribution and Habitat: —Currently known only within the forest over karst limestone areas of the Loboc Watershed Forest Reserve (LWFR) at 250–260 m elevation.

Eponymy: —The name ‘calcicolus’ is an epithet combination derived from the Latin words ‘ calci’ referring to the Calcium content of the limestone substrate, and ‘ colus’ derived from Latin incola (dweller) in reference to the unique karstic substrate of the Bohol island where this new species was found.

Phenology: —Flowering from June to July.

Proposed Conservation Status: — Amorphophallus calcicolus is currently known only from the type locality. The plant appears to be restricted only within the bounds of the protected area. Observations made in situ satisfy the IUCN category of Critically Endangered (CR), with less than 250 mature individuals observed with an extent of occurrence (EOO) of <100km 2, and an area of occupancy of <10km 2 ( IUCN Standards and Petitions Committee 2019). Moreover, development of facilities for tourism purposes within the area also poses a potential threat to the diminishing number of individuals in the population.

Notes: — Amorphophallus calcicolus closely resembles the more widespread A. longispathaceus ( Fig. 4 ) but can be distinguished by its shorter peduncle (48–75 cm vs. 60–130 cm), shorter spadix (16–30 cm vs. 42–60 cm), inner surface of the spadix (densely clothed with ovoid or irregularly shaped warts towards the base vs. densely clothed with short and long, simple or branched, fleshy or flaky, purple to reddish or brown finger like warts), shorter female zone (2.0–3.0 cm vs. 4.0– 8.5 cm), shorter male zone (1.7–2.5 cm vs. 4.5–6.5 cm long), depressed disk-shaped ovaries (vs. subglobose or depressed globose), longer style (5.0–8.0 mm vs. 2.0–5.0 mm), and the shallowly lobed stigma (vs. appearing claw-like). The notably long styles of A. calcicolus is also unique amongst all the known species in the Philippines.

Moreover, the foliage of the new species appears to be variable. Observations made in situ affirms that the species possesses 2 different leaf morphologies—a lanceolate leaf and a much broader one which are sympatric in the type locality. Population assessment done in June 2019 and June 2020 confirmed that although there are 2 leaf morphologies for the species, the flower characters are the same (i.e. spathe shape and coloration, warts in the inside of spathe, length of the style, a shallowly 2–3-lobed stigma, and the depressed disk-shaped ovary) (Sumalinog pers. obs.). As of writing, only A. calcicolus and A. paeoniifolius are recorded within the island of Bohol. The distribution of A. calcicolus is currently known as restricted within the karst of the Loboc Watershed Forest Reserve (LWFR).

Figures

FIGURE 2. Amorphophallus calcicolus, sp. nov. A. Habit in situ (lateral view of inflorescence); B.Anterior view of young inflorescence; C. Female and male flower details including the details of the inside of spathe; D. Leaves; E. Tuber; F. Detail of the petiolar markings. Photos A, C–F by M. Sumalinog, Jr.; B by M.N. Tamayo.

FIGURE 3. Amorphophallus calcicolus, sp. nov. A. Leaves; B. Female and male flower details including the details of the inside of spathe; C. Anterior view of the inflorescence; D. Anterior view of the ovary; D’. Ovary longitudinal section; E. Detail of the stigma (top view); F. Cross-section of the inside of the spathe base. Illustration by M.N. Tamayo.

FIGURE 4. Photo comparison of Amorphophallus calcicolus vs. A. longispathaceus. A. A. calcicolus inflorescence details; B. A. longispathaceus inflorescence details; C. A. calcicolus leaves; D. A. longispathaceus leaves. Photos A & C by M. Sumalinog, Jr., B & D by J.M. Agcaoili.