Psychotria pendens (Rubiaceae, Psychotrieae), a new ultramafic species from Central Palawan, Philippines Author Bautista, Mary Ann C. 0000-0002-5614-7170 Center for Conservation Innovations Ph, Inc., Alabang, Muntinlupa City 1770, Philippines m.bautista@conservation-innovations.org Author Chua-Mangussad, Vernaluz 0000-0002-6858-5362 Biophysical Sciences Department, College of Sciences, Palawan State University, Tiniguiban Heights, Puerto Princesa, Palawan 5300, Philippines vmangussad@psu.palawan.edu.ph Author Cervancia, Jehson 0000-0002-2680-5427 Philippine Taxonomic Initiative, Inc., Angeles City, Pampanga, 2900 Philippines cjehson@yahoo.com Author Bustamante, Rene Alfred Anton 0000-0002-2492-211X Philippine Taxonomic Initiative, Inc., Angeles City, Pampanga, 2900 Philippines rbustamante@phtaxa.org text Phytotaxa 2024 2024-05-21 649 3 252 260 http://dx.doi.org/10.11646/phytotaxa.649.3.2 journal article 10.11646/phytotaxa.649.3.2 1179-3163 13216087 Psychotria pendens M. Bautista & R. Bustam. , sp. nov . ( Figures 1–2 ) Type:— PHILIPPINES , Palawan , Malinao , Mount Victoria , ca. 500 m , January 2022 , MVIC26 , ( holotype : PNH ; isotypes : PPC , USTH ) . Description:— Psychotria pendens closely resembles Psychotria rubiginosa Elmer (1906: 25) ex Merr. (1906: 135) by having monochotomous inflorescence and oblanceolate to oblong-elliptic leaves, but differs in the large, leaf-like, valvate stipules with attenuate to acuminate cleft lobes (vs. small, valvate stipules with aristate cleft lobes), slightly corrugated leaves with the glabrous abaxial surface (vs. flat leaves with pubescent to puberulous abaxial surface), pendent inflorescence (vs. erect inflorescence), narrowly triangular bracts (vs. ovate triangular bracts), glabrous calyx (vs. pubescent calyx) ( Table 1 ). Evergreen shrub or small tree, 1–4 m high; young stem puberulous, mature parts glabrous. Stipules valvate, semi-persistent, conspicuous, almost leaf-like, broadly lanceolate to elliptic, 2–3 cm long, apex distinctly cleft (bilobed), cleft lobes margin densely pubescent, attenuate to acuminate tip. Leaves simple, opposite; petioles 1–2 cm long, glabrescent or puberulous to pubescent; leaf blades oblanceolate to oblong-elliptic, 12–25 cm long, 4.5 – 7 cm wide, acuminate at apex, attenuate to acute at base, subcoriaceous, slightly corrugated (raised beneath, impressed above); adaxial side dark green, abaxial side light green; midrib slightly raised adaxially and prominent abaxially, secondary veins 12–16 on each side, distinctly united submarginally, tertiary venation manifest, glabrous. Inflorescence monochotomous, pendent, 10–18 cm long, pubescent to densely pubescent, indumentum drying reddish-brown; principal axis/peduncle 5–8 cm long with 4–5 primary nodes, verticillate branching at each node, branches terminating in cymules; bracts narrowly triangular, 3–4 mm long, pubescent; bracteoles ovate-triangular, ca. 1.5 mm long, pubescent. Flowers 5- merous; pedicels 1.5–2 mm long; calyx including hypanthium 2.5–3 mm , external surface glabrous, calyx lobes orbicular to broadly ovate; corolla white, corolla tube 3.5–4 mm long, glabrous, villous at throat within, corolla lobes ca. 2–2.5 mm ; stamens ca. 3.5–4mm long, filaments ca. 2–2.5 mm , anthers ca. 1.5 mm , style ca. 3 mm ; ovary ca. 2 mm . Fruits globoid or ellipsoid, 5–7 mm , ribbed or ridged upon drying, orange upon maturity, glabrous; pedicels 1–2 mm long; calyx limb and lobes persistent; pyrenes 2, elliptic-obovate, ribbed/ridged, endosperm ruminate. TABLE 1. Morphological comparisons between Psychotria pendens and P. rubiginosa .

Psyhotria pendens	Psychotria rubiginosa
Stem	puberulous to glabrous	pubescent to puberulous
Stipule
type	valvate, semi-persistent	valvate, caducous to semi-persistent
appearance	conspicuous due to its leaf-like appearance	distinct due to the ‘shoulder’-like bumps at the base
size	2–3 cm long	0.7–1.2 cm long
apex	apex distinctly cleft (bilobed), lobes attenuate to acuminate	apex partially to distinctly cleft, lobes almost aristate
indumentum	pubescent, particularly in the cleft lobes margin	usually pubescent all throughout the stipule
Leaf
petiole	1–2 cm long	1.5–4 cm long
size	12–25 cm long, 4.5–7 cm wide	19–33 cm long, 4.1–11.6 cm wide
appearance	slightly corrugated (raised beneath, impressed above)	flat
indumentum	glabrous	rufous pubescent to puberulous below (hairs with bulbous bases)
Inflorescence and Infructescence
pattern and length	monochotomous, pendent, 10–18 cm long	monochotomous, erect, 13–28 cm long
bracts	narrowly triangular, 3–4 mm long	ovate triangular, 2–2.5 mm long
calyx size	calyx including hypanthium 2.5–3 mm	calyx including hypanthium 1.9–2.3 mm long
calyx indumentum	external surface glabrous	external surface pubescent to puberulous
calyx lobes	orbicular to broadly ovate	broadly ovate or obscure
corolla tube	3.5–4 mm long	2–3 mm long
corolla lobes	2–2.5 mm long	ca. 1.5 mm long
fruit	globoid or ellipsoid	globose-turbinate or obovoid

FIGURE 1 . Psychotria pendens M. Bautista & R. Bustamante.A. Habit ; B. Adaxial leaf surface; C. Abaxial leaf surface; D. Inflorescence; E. Flower (side view); F. Fruit (side view); G. Fruit (cross-section) H. Stipule. Illustrated by Julieferd C. Torres. FIGURE 2. Psychotria pendens M. Bautista & R. Bustamante.A. Habit ; B. Adaxial leaf surface; C. Abaxial leaf surface; D. Inflorescence; E. Flower (side view); F. Fruit (side view); G. Fruit (cross-section) H. Stipule. Photographs were taken by R. Bustamante (A), A. Langbao (B–C), M. Bautista (D–F, H), and D. Salas (G). Phenology:— The species was observed flowering during the months of January, February, and July, fruiting during the month of July. Habitat and Ecology:— It grows with other Psychotria species in the moist and shady areas of lowland to midelevation forest ( 400–600 m ) in Mt. Victoria. Distribution:— Psychotria pendens is currently known from the type locality in Mt. Victoria, Palawan , Philippines ( Figure 3 ). FIGURE 3. Type locality of Psychotria pendens in Mt. Victoria, Palawan. Dot map prepared by J.L. Bibar. Etymology:— The specific epithet ‘ pendens ’ was derived from Latin, meaning ‘to hang’ in reference to the long, pendent inflorescence. Proposed IUCN status:— Following the IUCN Red List categories and criteria ver. 16 (2024), we herein propose this species to be classified as Critically Endangered CR B1ab(iii)+2ab(iii) as the extent of occurrence (EOO) is approximately less than 100 km 2 and the area of occupancy (AOO) is less than 10 km 2 . P. pendens has a restricted distribution and a relatively small number of mature individuals (less than 10 mature individuals observed in the type locality). Notes:— The new species is quite distinct by having large semi-persistent stipules and pendent inflorescence. These characters are in contrast with other known species of Psychotria in the Philippines as most species have caducous stipules and erect inflorescence. Molecular analysis :—To check the possible phylogenetic placement of Psychotria pendens within Psychotrieae , we sequenced the highly divergent DNA regions ( rbc L, rps 16, trn L-F, nrITS). The resulting tree does not provide robust taxonomic support due to limited taxonomic sampling but based on molecular analysis, it can be inferred that the new species Psychotria pendens and the widespread Philippine species Psychotria luzoniensis (Cham. & Schltdl.) Fern —Vill. (1880: 112) are closely related to Hawaiian Psychotria and they belong to the same clade as Amaracarpus Blume (1826: 954) , Calycosia A.Gray (1860: 47) , and other Pacific (New Guinea , Fiji ) species of Psychotria ( Figure 4 ). Piesschaert's (2001) pyrene data is consistent with this topology, as most species he investigated in Indonesia , the Philippines , New Guinea , and Fiji have distinct marginal pre-germination slits (PGSs) and an abaxial surface with few or incomplete ridges. These characters suggest inclusion in the Pacific clade ( Andersson 2002 ). The topology is also parallel to the Pacific clade presented in the broader molecular analysis of Razafimandimbison et al. (2014) , which formally transferred all allied genera (including Amaracarpus and Calycosia ) to Psychotria . FIGURE 4. Maximum-likelihood tree showing the phylogenetic placement of Psychotria pendens within Rubiaceae . Numbers on each node represent the bootstrap support values. Psychotria pendens and P. luzoniensis have higher affinities to the Hawaiian species, P. mariniana (Cham. & Schltdl.) Fosberg (1962: 43) , compared to other species included in the analysis. Andersson (2002) emphasized that several species from the Philippines , Borneo, Fiji , Solomon Islands , and New Guinea could be related to Hawaiian Psychotria due to their similar carpological features presented in Piesschaert's (2001) dissertation report. They all possessed long marginal PGSs with ventrally ruminate endosperm. However, the current taxonomic samples and amount of sequence data do not provide sufficient information to define taxonomic relationships. The sister-group relationship between Philippine Psychotria and Hawaiian Psychotria remains unclear. Additional sequences from Southeast Asia and the Pacific region might give a better representation of the specific relationships among the Pacific clade, including the Hawaiian and Philippine species. On the other clade, only Psychotria manillensis Bartl. ex DC. (1830: 522) and P. cephalophora Merr. (1908: 438) have grouped with the Tropical Afro-Asian Psychotria clade. Morphologically, these two closely resemble the type species P. asiatica Linnaeus (1759: 929) . Like P. asiatica , these species exhibit the ‘classic’ Psychotria characters such as caducous stipules, ethanol-soluble seed coat pigment, and reddish-brown leaf color upon drying.