Philodendron melloi Irume, M.V. & M.L. Soares, 2017

Irume, Mariana Victória, Soares, Maria De Lourdes, Mayo, Simon J., Carvalho, Rangel Batista & Zartman, Charles E., 2017, Philodendron melloi (Araceae), a new species from central Amazonia, Brazil, Phytotaxa 319 (2), pp. 184-190 : 185-189

Philodendron melloi Irume, M.V. & M.L. Soares sp. nov. ( Figs. 1–3 )

Philodendron melloi is similar to P. barrosoanum Bunting (1964: 23) and P. hylaeae Bunting (1975: 298) , but differs from these species principally due to a combination of the following characteristics: Its preferably terrestrial habitat, persistence of the prophyll, intermediate-sized width of leaf base at the anterior division (1.5–5.6 cm), oblong sinus, floral sympodium with 1–4 inflorescences, 3–6 locules per ovary, and a large number (15–25) of ovules per locule, inserted along the entire length of the placenta. The other two species only have 5 (4–6) and 2 ovules per locule, respectively.

Type: — BRAZIL. Amazonas: Manaus, central Amazonia, Adolpho Ducke Forest Reserve-RFAD, Camping Bolívia, S 02º 58’ 21.9” W 059º 57’ 28.4”, 10 January 2017 (fl., fr.), Irume, M. V. 72 (holotype and isotypes INPA 277451!).

Plant terrestrial, infrequently pendant in trees as nomadic vines and rarely rupiculous, erect-scandent. Roots climbing purple when young, brown when mature, roots aerial 0.3– 1 cm in diameter, grey in colour. Stem decumbent 8.0– 15.5 × 1.0–2.0 cm, light brown, internodes short, 1.0–2.0 × 0.8–2.5 cm. Prophyll 4.5–16.8(–20) × 0.6–2.5 cm, pink coloured, infrequently pink-green, longitudinally striped, persistent without forming fibers, when dry becoming pendent, orange-dark brown, recurved apex, stain darker, resin transparent with a sweet fragrance. Petiole 24.5–59.4 × 0.2–0.8 cm, subcylindrical, slightly sulcate on the adaxial face, dark-opaque green, apex purplish pink forming a ring, pulvinus 0.2–0.8 cm × 0.2–1.0 cm, with proximal white stripes at the insertion of the leaf lamina, extrafloral nectaries present at the apex, base inflated, greenish-yellowish-pink, resin transparent with a sweet fragrance. Leaf blade trifid, hastate, subcoriaceous, adaxial face brilliant light and dark green, when young, dark grey-green, abaxial face light green-opaque, entire margin, pink to dark yellowish, apex strongly acuminate. Anterior division 20.2–32.6 × 6.2–13.1 cm, oblanceolate, apex acuminate 0.5–2.3 × 0.1–0.8 cm, width of base at the anterior lobe 1.5–5.6 cm. Principal vein impressed on the adaxial face, prominent raised on the abaxial face, dark green on the adaxial face, green-yellow on the abaxial face. Primary lateral veins 3–7 pairs on both sides, concolorous, impressed on the adaxial face, raised and well developed on the abaxial face, interprimary veins impressed on both faces. Posterior division lobes 14.4–25.5 × 4.3–10.8 cm, slightly asymmetrical, lanceolate-oblanceolate in form, apex slightly acuminate, lobes in almost patent position, acroscopic veins 1–4, basioscopic veins 2–5, interprimary veins impressed on both faces, sinus oblong. Floral sympodium 1–4 inflorescences, floral button pink-green to yellowish, apex apiculate, longitudinal stripes clear, floral cataphyll 4.0–10.1. × 1.0– 1.8 cm, pink to clear brown. Peduncle 5.2–10.6. × 0.1–0.3 cm, subcylindrical, clear green-white, stripes stained vertically white near the insertion of the spathe, resin transparent with sweet fragrance. Spathe 4.2–6.2 cm long, slightly constricted, on both faces light green-white, apex apiculate, clear green, tube light green, longitudinal stripes, resin canals present, resin orange with a sweet fragrance, blade 2.3–3.5 × 0.5–1.8 cm, tube 2.0–3.0 × 0.8–2.1 cm. Spadix 3.0– 6.8 cm long, apex rounded, fertile male zone 1.4–3.1 × 0.3–0.8 cm, white to light beige, resin dark orange with a sweet fragrance, intermediate sterile male zone 0.4–0.8 × 0.3–0.8 cm, light pink-orange, female zone 0.9–2.9 × 0.5–1,7 cm, light yellowish-green, stipe 0.2–0.5 × 0.2–1.2 cm, light green-white. Stamens 3–4(–6), 1.2–1.3 × 0.7–0.9 mm at the apex, resin dark orange, with a sweet fragrance. Staminodes 0.7–0.8 × 1.1–1.3 mm at apex. Gynoecium 2.2–3.0 × 1.1–1.5 mm at apex, ovary external trichomes 0.1 mm lenght, crystals of raphides in the epidermis, globose stigma, presence of unicellular trichomes in tufts, axile placentation, locules 3–6, mutilagenous substance transparent in colour, ovules 15–25 for each locule, inserted along the entire length of the placenta, hemianatropous, funicle one to two times longer than the ovules, trichomes at the base and intermediate part of the funicle. Infructescence 4.2–5.5 × 1.2–2.7 cm. Fruits berries, dark orange, 0.3–0.7 cm × 0.1–0.2 cm in diameter, when immature light yellow, seeds very numerous, ca. 1 mm, oblong, succulent, longitudinally striped, presence of crystals of raphides in the epidermis.

Etymology: —The specific epithet is given in honor of a technician and parataxonomist Antônio Tavares Mello (“Cachorrinho”), who contributed in an essential way to find, recognize, and collect the new species in the field. His dedication in collaborating with us to gather several additional specimens essential for the description of the species is greatly appreciated.

Phenology: —Inflorescences were collected in anthesis between the months of October and January.Infructescences were collected mature in April.

Distribution and Ecology: —The occurrence of Philodendron melloi was registered from “terra firme” (upland) humid tropical rainforests in central Amazonia, in the state of Amazonas, Brazil, at elevation between 39–109 m ( Fig. 1 ). The local distribution of the newly described species is restricted to points indicated on the map where the individuals occur on the ground in densely aggregated populations, where only 1 to 2(–3) fertile individuals were located.

Conservation: — Philodendron melloi presents an aggregated spatial distribution and is restricted to certain points in terra-firme upland forests. In light of this, anthropogenic disturbance in the region as a result of deforestation, habitat fragmentation and excessive selective extraction without management plans are the greatest threats to this species in its habitat.

Comments: —Morphologically Philodendron melloi is similar and comparable to P. barrosoanum and P. hylaeae , both of which also occur at RFAD. However, various morphological characteristics (both vegetative and reproductive) may be used to distinguish it from these other two species (see Table 1).

The morphological comparison details three species revealing that P.melloi exhibits a series of unique characteristics indicating it as a new taxon to science. Its preferably terrestrial habitat, persistence of the prophyll, intermediate-sized width of leaf base at the anterior division (1.5–5.6 cm), oblong sinus, floral sympodium with 1–4 inflorescences, 3–6 locules per ovary, and a large number (15–25) of ovules per locule, inserted along the entire length of the placenta, are some of the characteristics which distinguish the new species from morphologically similar ones (see Table 1).

Paratypes:— BRAZIL. Amazonas — AM: Manaus, Adolpho Ducke Forest Reserve ( RFAD), Cultivated in vase at INPA, 02º 56’ 06.4” S, 59º 53’ 59.7” W, 09 December 2015 (fl.), Irume, M. V. 68 ( INPA 277446 !) ; Camping Bolívia , 02º 58’ 21.9”S, W 59º 57’ 28.4” W, 4 October 2016 (fl.), Irume, M. V. 69 ( INPA 277448 !) ; 10 January 2017 (fl., fr.), Irume , M. V. 72 ( INPA 277451 !) ; Presidente Figueiredo, Vila de Balbina, Trilha da Bica do Cabeça , 01º 56’ 27.4” S, 59º 25’ 43.1” W, 6 December 2015 (fl.), R. O. Perdiz 2975 ( INPA 277447 !) ; Trilha da Cachoeira da Sussuarana , 01º 54’ 23.6” S, 59º 24’ 41.1” W, 22 October 2016 (fl.), Irume, M. V. 70 ( INPA 277449 !) ; Trilha da Cachoeira Berro d’água, 02º 03’ 9.28” S, 59º 56’ 11.6” W, 03 January 2017 (fl.), Irume, M. V. 71 ( INPA 277450 !) ; Trilha da Cachoeira da Maroca , 02º 00’ 48” S, 59º 51” 0.4” W, 12 April 2017, Irume, M. V. 73 (fr.) ( INPA 277452 !) .

Figures

FIGURE 1. Map showing the locality data for the collection points of fertile populations of Philodendron melloi in central Amazonia.

FIGURE 2. Philodendron melloi. A. Habit. B. Plasticity foliar in ontogenetic development of leaves. C. Detail of the form and width of the base of the anterior lobe, the abaxial and adaxial leaf faces. D. Inflorescence in a transversal cut. E. Peduncle and stipe. F.Prophyll. G. Frontal view of the inflorescence and detail of the persistent prophyll H. Staminate fertile flowers on a superior view. I. Staminate fertile flowers in a transversal cut and a lateral view. J. Sterile staminodes in a lateral view. K. Detail of ovules and trichomes L. Gynoecium in a lateral view showing locules with ovules and details of the external trichomes on the stigma M. Gynoecium in a longitudinal cut, show axile placentation and ovules inserted into the entire length of the placenta. N. Transversal cut of the ovary.

FIGURE 3. Philodendron melloi. A. Habit. B. Left blade adaxial surface. C. Left blade abaxial surface. D. Prophyll. E. Inflorescence in anthesis at the ground. F. Sympodium floral with four inflorescences. G. Inflorescence and floral button, adaxial side. H. Inflorescence and floral button, detail of spathe and floral cataphyll, abaxial side. I. Detail staminate zone, male-sterile zone, pistillate zone and stipe. J. Fertile collect. K. Infrutescence mature. L. Detailed view of the distinctive vegetative characters between similar species collected in RFAD, P. melloi (on top), P. barrosoanum (on the left side) and P.hylaeae (in the right side) respectively.