Argostemma mirae (Rubiaceae) a new species from Tago, Surigao del Sur, Mindanao Island, Philippines Author Blasco, Freddie A. College of Arts & Sciences Department, Saint Theresa College of Tandag, Tandag City 8300, Surigao del Sur, Philippines Author Tandang, Danilo N. Philippine National Herbarium, Botany and National Herbarium Division, National Museum of Natural History, National Museum of the Philippines, T. M. Kalaw St., Manila 1000, Philippines & Biodiversity Program, Taiwan International Graduate Program, Academia Sinica and National Taiwan Normal University, Taipei, 11529, Taiwan & Department of Life Science, National Taiwan Normal University, Taipei 11677, Taiwan & Biodiversity Research Center, Academia Sinica, Taipei 11529, Taiwan Author Alejandro, Grecebio Jonathan D. College of Science and Research Center for the Natural and Applied Science, University of Santo Tomas, España, Manila 1015, Philippines text Phytotaxa 2024 2024-03-07 640 1 65 70 http://dx.doi.org/10.11646/phytotaxa.640.1.7 journal article 10.11646/phytotaxa.640.1.7 1179-3163 13213500 Argostemma mirae Blasco, Tandang & Alejandro , sp. nov. ( Fig. 1 ). Type— PHILIPPINES . Mindanao Island, Surigao del Sur , Tago, Badong, Mt. Tingtingan, elev. ca. 10m . It grows on a shady mossy limestone forest on a lower elevation. 22 May 2022 Freddie A . Blasco 22-002 ( holotype PNH , isotype USTH ) Diagnosis — Argostemma mirae closely resembles A. solaniflorum Elmer over A. arachnosum Merrill and A. distichum Valeton in having erect, branching and pubescent stems, glabrous stipules, pubescent petioles, oblanceolate leaves, dark green lamina, abaxially pubescent leaf surface, acute base, margin entire, pubescent calyx lobes, corolla lobes surface abaxially pubescent, white corollas and pubescent pedicel but differs in having shorter stems 10–13 cm . (vs. 16), stipules broadly ovate (vs. oblong), smaller leaf blades 2.5–3. × 1– 1.3 cm (vs. 7 × 2), acuminate apex (vs. obtuse), adaxially glabrous leaf surface (vs. pubescent), lateral leaf veins 4–5 pairs (vs. 7–8), inflorescences 2 (vs. 5), 4 calyx lobes (vs. 5), 4 corolla lobes (vs. 5 star-shaped), corolla lobes surface adaxially glabrous (vs. pubescent), longer pedicel 15–17 mm (vs. short 8), anthers length 3–4 mm (vs. 7) and opening by longitudinal slits (vs. apical pore). Lithophytic herb, Stem , 10–13 cm tall, 2.5–3 mm in diameter, pubescent, erect and branching, internodes 5–7 mm long, terete. Stipules persistent, broadly ovate, 5–6 × 3–4 mm , glabrous, apex acuminate, margin entire. Leaves glabrous, glossy, oblanceolate, petiole 4–5 mm long, terete, pubescent, blade 2.5–3. × 1–1.3 cm , apex acuminate, margin entire, obliquely acute base , adaxial surface glossy, glabrous, dark green with prominent midrib and veins, abaxial surface light green and hairy with distinct pubescent midrib, lateral veins 4–5 pairs. Inflorescence terminal to axillary, cymose, 2–flowered, peduncle pilose, 8–10 mm , bracts 3–4 × 1–2 mm persistent and pubescent, ovate, pedicel 15–17 mm long. Calyx lobes 4, triangular to narrowly triangular, gamosepalous, hypanthium, infundibuliform, pubescent. Corolla lobes 4, white, adaxially glabrous, abaxially pubescent 6–7 × 3–5 mm , broadly ovate when young, narrowly triangular when mature, apex acuminate. Stamens 4, 5–6 mm long, filaments short, anthers yellow, 3–4 mm long. Ovary inferior, bilocular, ovules numerous, style 4–5 mm long, stigma 2–3 mm long, simple, exserted. Fruit obovoid, 5–6 × 4–5 mm , pubescent, crowned by a persistent calyx, opening by longitudinal slits. Phenology —Observed flowering and fruiting in April to May when the dry season is at its peak. Etymology —The species is named after Mrs. Evangeline A. Mira to honor her 45 years of service to Saint Theresa College of Tandag. Ma’am Mira, as she is fondly called by her students, colleagues and friends is a biology and language teacher and a dear friend. FIGURE 1. Argostemma mirae Blasco, Tandang & Alejandro. A. Habit & Habitat ; B. Young flower; C. Matured flower; D. Fruit. Distribution and Ecology —Endemic to the province of Surigao del Sur , CARAGA Region Eastern Mindanao, Philippines . It grows on a shady, mossy limestone forest on a lower elevation in Mt. Tingtingan, Badong, Tago, Surigao del Sur , elev. 10 m asl. Notes— Argostemma mirae superficially resembles A. distichum Valeton in having branching stems, broadly ovate stipules, dark green lamina, entire margin, 4 glabrous white corollas, and longitudinal slits dehiscence. However, the new species is distinct in having erect and longer stems (vs. creeping), larger leaves, acuminate apex (vs. sharplyacute), numerous major leaf veins 4–5 (vs. 1–2), longer pedicel and anthers, and 2-flowered inflorescence (vs. multi-flowered 5–6). It is also comparable to A. arachnosum Merrill in having pubescent stems, glabrous stipules, acuminate apex, pubescent calyx lobes, white corollas, and longitudinal slits dehiscence, but differs in having shorter erect stems (vs. creeping, solitary), dark green lamina (vs. light green with green sparse), acute leaf base (vs. cordate-rounded) longer pedicel 15–17 mm (vs. 10–12 mm .), 2-flowered inflorescence (vs. multi-flowered 10–25), and 4 corolla lobes (vs. 5 star-shaped). Table 1 offers a thorough comparison of A. mirae and its allied species. FIGURE 2. Map of Mindanao showing the distribution of Argostemma mirae (green). TABLE 1. Comparative morphology among Argostemma mirae , A. arachnosum , A. distichum and A. solaniflorum .
Characters A. mirae A. arachnosum A. distichum A. solaniflorum
Stems and height in cm. Erect, branching, pubescent. 10–13 Creeping, solitary, pubescent. 20 Creeping, branching, glabrous. 5–10 Erect, branching, pubescent. 16
Stipules Broadly ovate, glabrous Oblong, glabrous Broadly ovate, hairy Oblong, glabrous
Leaf blade lamina and shape Dark green. Oblanceolate Light green with light green sparse. Oblong- elliptic Dark green. Ovate- lanceolate Dark green. Oblanceolate
Leaf blade size cm. 2.5–3 × 1–1.3 4.5–8 × 1.8–2.5 1.8–2.5 × 0.5 7 × 2
Leaf Apex Acuminate Acuminate Sharply acute Obtuse
Leaf surfaces Adaxially glabrous, abaxially pubescent Adaxially glabrous, abaxially pubescent Adaxially and abaxially pubescent Adaxially and abaxially pubescent
Leaf Base Acute Cordate-rounded Acute Acute
Leaf Margin Entire Sinuate Entire Entire
Lateral leaf veins in pairs 4–5 8 1–2 7–8
Inflorescence 2 10–25 5–6 5
Calyx lobes 4 pubescent 5 pubescent 4 glabrous 5 pubescent
Corolla lobes 4 glabrous both adaxially, and abaxially 5 pubescent both adaxially and abaxially 4 glabrous both adaxially, abaxially 5 pubescent both adaxially and abaxially
Pedicel mm. 15–17 pubescent 10–12 pubescent 3–5 pubescent 8 pubescent
Anthers length mm. 3–4 10–12 1–5 7
Anthers dehiscence Longitudinal slits Longitudinal slits Longitudinal slits Apical pore
Proposed IUCN category:— Mt. Tingtingan has not been explored by any researchers due to the peace and order situation, which can make it hard to assess the conservation status of the species. The location is not a protected area. Although there is only one population currently known, there are several individuals found in a moist shady, mossy limestone in an undisturbed forest. We recommend a conservation status of data deficient [DD] ( IUCN, 2022 ).