Psychotria pendens (Rubiaceae, Psychotrieae), a new ultramafic species from Central Palawan, Philippines Bautista, Mary Ann C. Chua-Mangussad, Vernaluz Cervancia, Jehson Bustamante, Rene Alfred Anton Phytotaxa 2024 2024-05-21 649 3 252 260 M. Bautista & R. Bustam. M. Bautista & R. Bustam. [136,663,1428,1455] Magnoliopsida Rubiaceae Psychotria Plantae Gentianales 1 253 Tracheophyta species pendens sp. nov.   Type:—  PHILIPPINES, Palawan, Malinao, Mount Victoria, ca.  500 m,  January 2022,  MVIC26, ( holotype:  PNH; isotypes: PPC, USTH).   Description:—  Psychotria pendensclosely resembles  Psychotria rubiginosaElmer (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 mhigh; young stem puberulous, mature parts glabrous. Stipules valvate, semi-persistent, conspicuous, almost leaf-like, broadly lanceolate to elliptic, 2–3 cmlong, apex distinctly cleft (bilobed), cleft lobes margin densely pubescent, attenuate to acuminate tip. Leaves simple, opposite; petioles 1–2 cmlong, glabrescent or puberulous to pubescent; leaf blades oblanceolate to oblong-elliptic, 12–25 cmlong, 4.5 –7 cmwide, 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 cmlong, pubescent to densely pubescent, indumentum drying reddish-brown; principal axis/peduncle 5–8 cmlong with 4–5 primary nodes, verticillate branching at each node, branches terminating in cymules; bracts narrowly triangular, 3–4 mmlong, pubescent; bracteoles ovate-triangular, ca. 1.5 mmlong, pubescent. Flowers 5- merous; pedicels 1.5–2 mmlong; calyx including hypanthium 2.5–3 mm, external surface glabrous, calyx lobes orbicular to broadly ovate; corolla white, corolla tube 3.5–4 mmlong, glabrous, villous at throat within, corolla lobes ca. 2–2.5 mm; stamens ca. 3.5–4mmlong, 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 mmlong; calyx limb and lobes persistent; pyrenes 2, elliptic-obovate, ribbed/ridged, endosperm ruminate.   TABLE 1.Morphological comparisons between  Psychotria pendensand  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 pendensM. 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 pendensM. 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  Psychotriaspeciesin the moist and shady areas of lowland to midelevation forest ( 400–600 m) in Mt. Victoria.   Distribution:—  Psychotria pendensis currently known from the typelocality in Mt. Victoria, Palawan, Philippines( Figure 3).   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 2and the area of occupancy (AOO) is less than 10 km 2.  P. pendenshas a restricted distribution and a relatively small number of mature individuals (less than 10 mature individuals observed in the typelocality).  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  Psychotriain the Philippinesas most species have caducous stipules and erect inflorescence.  Molecular analysis:—To check the possible phylogenetic placement of  Psychotria pendenswithin Psychotrieae, we sequenced the highly divergent DNA regions ( rbcL, rps16, trnL-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 pendensand the widespread Philippine species  Psychotria luzoniensis(Cham. & Schltdl.) Fern—Vill. (1880: 112) are closely related to Hawaiian  Psychotriaand they belong to the same clade as  AmaracarpusBlume (1826: 954),  CalycosiaA.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 Fijihave 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  Amaracarpusand  Calycosia) to  Psychotria.   FIGURE 4.Maximum-likelihood tree showing the phylogenetic placement of  Psychotria pendenswithin Rubiaceae. Numbers on each node represent the bootstrap support values.   Psychotria pendensand  P. luzoniensishave 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 Guineacould be related to Hawaiian  Psychotriadue 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  Psychotriaand Hawaiian  Psychotriaremains 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 manillensisBartl. ex DC. (1830: 522)and  P. cephalophoraMerr. (1908: 438)have grouped with the Tropical Afro-Asian  Psychotriaclade. Morphologically, these two closely resemble the typespecies  P. asiaticaLinnaeus (1759: 929). Like  P. asiatica, these species exhibit the ‘classic’  Psychotriacharacters such as caducous stipules, ethanol-soluble seed coat pigment, and reddish-brown leaf color upon drying. 4924365302 [218,1157,1504,1526] 2022-01 PNH, PPC, USTH Philippines 500 Mount Victoria Malinao 1 253 MVIC26 2 Palawan holotype 4924365301 [1162,1442,1504,1526] 2022-01 PNH, PPC, USTH Philippines 500 Mount Victoria Malinao 1 253 MVIC26 2 Palawan holotype