Three new species of Trivalvaria (Annonaceae) from Thailand, with a key to the Thai species Author Johnson, David M. 0000-0003-2896-7419 dmjohnso @ owu. edu; https: // orcid. org / 0000 - 0003 - 2896 - 7419 dmjohnso@owu.edu Author Chaowasku, Tanawat 0000-0002-1602-8468 Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand & tanawat. chaowasku @ cmu. ac. th; https: // orcid. org / 0000 - 0002 - 1602 - 8468 tanawat.chaowasku@cmu.ac.th Author Murray, Nancy A. 0000-0003-4076-6169 namurray @ owu. edu; https: // orcid. org / 0000 - 0003 - 4076 - 6169 namurray@owu.edu Author Chalermglin, Piya 0000-0002-9098-0916 Agricultural Technology Department, Thailand Institute of Scientific and Technological Research, 35 Mu 3, Khlong Ha, Khlong Luang District, Pathum Thani Province 12120, Thailand & piya. chalerm @ gmail. com; https: // orcid. org / 0000 - 0002 - 9098 - 0916 piya.chalerm@gmail.com text Phytotaxa 2021 2021-03-03 489 1 79 86 http://dx.doi.org/10.11646/phytotaxa.489.1.6 journal article 10.11646/phytotaxa.489.1.6 1179-3163 5757631 Trivalvaria stenopetala Chaowasku & D.M.Johnson , sp. nov . ( Figs. 1F–H , 2A,D ) Type :— THAILAND . Phangnga : Khao pawta luang keow, 8°30’N , 99°E , 1000–1200 m , 27 February 1974 (flower & fruit), Geesink et al. 7641 ( holotype : L .2066289!; isotypes: BKF-3981, 3397) . In its linear to lanceolate petals and oblong monocarps this new species most resembles T. pumila ( King, 1892: 27 ) Sinclair (1953: 48) but differs from that species in the sepals 3.3–5.0 mm versus 1.5–2.0 mm long, and the seed-containing portion of the monocarp 18.0– 21.5 mm long and borne on a glabrate stipe 0.8–2.5 mm long versus 12.0–19.0 mm long and borne on a sparsely pubescent stipe 4.0–5.0 (8) mm long ( Table 1 ). Shrubs and treelets up to 5 m tall. Twigs short grey-pubescent, eventually glabrate. Leaves narrowly oblong, or oblanceolate to narrowly oblong, occasionally elliptic, blade 14.0–28.8  (2.8–) 4.5–7.2 cm , base cuneate to rounded, apex acuminate, the acumen 7–28 mm long, glabrous on both surfaces, secondary veins eucamptodromous to weakly brochidodromous, 9–15 per side, arcuate; petiole 5.0–9.0 mm long. Inflorescences supra-axillary, 1-flowered, peduncle ca. 5 mm long, pedicels 4.0– 5.5 mm long, bearing 1 bract ca. 3.0 mm long; buds with petals separating well before anthesis. Flowers bisexual or staminate. Sepals triangular, 3.5–5.0 mm long, acute to acuminate, sericeous. Petals spreading at anthesis, creamy white, yellow, or pale orange, glabrous on inner surface, sericeous on outer surface, outer petals lanceolate to linear, 7.0–12.8  1.8–3.7 mm , acute, inner petals linear to linear-lanceolate, 8.0–15.5  1.6–3.2 mm , acute. Stamens ca. 150, forming a globose to oblong boss 5.0– 6.2 mm in diameter, oblong, 1.0– 1.9 mm long, anther connective apex truncate, glabrous. Carpels 9–18, ovaries ca. 1 mm long, pubescent, stigmas flat or globose, puberulent. Receptacle columnar, 1.7–3.5 mm high, 1.5–2.5 mm in diameter, glabrous. Fruit of up to 7 monocarps borne on a pedicel 5–8 mm long. Monocarps oblong, 18.0–21.5  7.0– 9.2 mm , verrucose and faintly ridged, glabrate, apex rounded to a beak 0.8–1.5 mm long, stipe 0.8–2.5 mm long, 2.0– 2.2 mm thick, pericarp ca. 0.2 mm thick. Seed narrowly ellipsoid, ca. 18.0 mm  7.5 mm , 7.0 mm thick, smooth, pale orange-brown. Distribution and Ecology:— Endemic to Peninsular Thailand , in evergreen forest at 900–1200 m . Phenology:— Flowering and fruiting November–February. Etymology:— Named for the narrow petals, unusual in the genus. Vernacular name:— Ma khao klip khaep (มะขาวกลีบแคบ) ( Ranong ). Conservation status:— Trivalvaria stenopetala is known from four localities in southern Ranong and northern Phangnga Provinces. Two localities lie within designated conservation areas (a national park and a wildlife sanctuary). It has been collected as recently as 2006. We give T. stenopetala a preliminary conservation assessment of data deficient. FIGURE 2. Photographs of new Trivalvaria species. A . Flower of Trivalvaria stenopetala , Phangnga Province, Thailand. B. Flower of Trivalvaria ochroleuca , Tak Province, Thailand. C. Flower of Trivalvaria recurva , Kanchanaburi Province, Thailand. D. Fruit of Trivalvaria stenopetala , Phangnga Province, Thailand. E. Fruit of probable Trivalvaria ochroleuca from Prachuap Khiri Khan Province, Thailand. F. Fruit of Trivalvaria recurva from Kanchanaburi Province, Thailand. A and D by Simon Gardner from Gardner et al. ST 1944 , B by Tanawat Chaowasku, C and F by Piya Chalermglin, E by Thammanoon Temchai. Additional specimens examined:— THAILAND . Phangnga : Khura Buri District , Chaowasku 73 ( CMUB ) ; Phang Nga , 300 m , Sri Phang Nga National Park , 8°59’N , 98°28’E , 21 Nov 2005 (flower & fruit), Gardner et al. ST 1944 ( BKF , L .2066288) . Ranong : Khao Por-ta-luang-kaew, 6 Dec 1994 (flower), Herb. Tr. 1034 (6/10) ( BCU , herb. no. 6224); Kao Pawte Luang Ko , ca . 900 m , 31 Jan 1929 (flower), Kerr 16924 ( BK , L .2066287); route to Mueang Chone , Klong Naka Wildlife Sanctuary , Suksamran , 900 m , 6 Nov 1999 (flower), Maknoi 70 ( QBG ) ; Suksamran District , Khlong Na Kha Wildlife Sanctuary , trail from Kam Puan Ranger Substation toward summit of Khao Dan , 9.316°N , 98.512°E , 1020 m , 22 Feb 2006 (flower), Middleton et al. 3915 ( A , BKF-159764, L .2066286); Kapoe , Khao Sungkha Tuk [=Langkha Teuk, ca. 9°20’N , 98°35’E ], 23 Nov 1965 (flower), Sangkhachand 1161 ( BKF ) . Notes:— Gardner et al. ST 1944, listed above, is identified and described as T. costata in Gardner et al. (2015) . Gardner ST 1311, identified as Polyalthia species D in the same publication, may also represent this species, but it has not been possible to see the specimen. It was collected from Phangnga Province at 300 m , a significantly lower elevation. This species was included in a molecular phylogenetic analysis by Chaowasku et al. (2020 , as “ Trivalvaria sp. 2 ”).