Meiogyne saundersii Junhao Chen & M. F. Liu sp. nov.

Figs 2 A, 3

Meiogyne cylindrocarpa auct. non (Burck) Heusden: van Heusden (1994), pro parte; Turner (2014); Thomas et al. (2012) and Xue et al. (2014) as ‘ Meiogyne cylindrocarpa subsp. cylindrocarpa 1 ’; Xue et al. (2021) and Jaikhamseub et al. (2022) as ‘ Meiogyne cylindrocarpa 1 ’; Liu et al. (2025 d) as ‘ Meiogyne cylindrocarpa (Borneo) ’.

Type.

Brunei • Temburong District: Kuala Belalong, Batu Apoi Forest Reserve, at the Kuala Belalong Fields Studies Centre, at the Sungai Belalong River upstream along path starting behind the houses, 4°33'N, 115°09'E, 7 Nov 1991, fl., C. Hansen 1511 (holotype: BRUN [acc no. B 004935!]; isotypes: K [K 003311883!], L [L 0047321!]).

Diagnosis.

Similar to Meiogyne cylindrocarpa in its relatively small leaves (typically <10 cm long), indistinct leaf venation and cylindrical monocarps, but differs in its leaf apex (abruptly caudate vs. acute, rarely shortly acuminate) and inner petal corrugation (tentacular vs. weakly longitudinally grooved). See notes for additional minor differences in fruit morphology and habit.

Description.

Tree or treelet 5–20 m tall, 8–25 (– 60) cm dbh, stilt roots or buttresses absent; bark greyish green to dark brown, smooth, rarely rugose. Twigs with dense minute short hairs when young, glabrescent, sometimes with raised lenticels. Leaves chartaceous to subcoriaceous, blades elliptic, (3.8 –) 5.1–10.6 cm long, (1.5 –) 2–3.2 (– 3.6) cm wide, base cuneate, apex abruptly caudate, the acumen (0.5 –) 1–2.4 cm long, glabrous adaxially except minute erect hairs on the midrib when young, glabrous to sparsely appressed hairy abaxially; midrib sunken adaxially, raised abaxially, secondary and tertiary venation indistinct; petiole 2–4 mm long. Inflorescences axillary, 1 - flowered; pedicel 4–7 mm long, 0.8–1 mm thick, densely appressed or short erect hairy, with 2–3 small bracts at the proximal end of the pedicel, sometimes with a medial bract. Buds conical, apex acute or obtuse. Sepals free, broadly ovate, 1–1.5 mm long, 1–2 mm wide, apex acute or obtuse, densely appressed hairy abaxially. Petals dull yellow except the dull purplish center, apex acute, sometimes rounded; outer petals triangular, 9–16 mm long, 3–4.5 mm wide, densely woolly hairy adaxially, sparsely appressed hairy abaxially; inner petals elliptic to ovate, 6–10.5 mm long, 4–5.5 mm wide, densely woolly hairy on both sides except the adaxial corrugated base, with a glabrous, tentacular corrugated patch on proximal 7 / 10–9 / 10 of adaxial surface. Stamens c. 45, wedge-shaped, c. 1 mm long, anther connective apex flat, often sunken in the middle, inner whorl of stamens with elongated connective apex. Carpels 5–11, ovary completely covered by long appressed hairs, stigma subglobose, sparsely puberulent. Fruits with 6–8 shortly stipitate monocarps borne on a globose receptacle, torus 3–4 mm in diameter, sparsely short hairy, stipe 1–4 mm long, 1–2 mm wide, sparsely to densely appressed hairy; fruiting pedicel 4–7 mm long, 1.2–1.5 mm wide, sparsely short hairy; monocarps (excluding stipe) short-cylindrical, 10–22 mm long, 6–11 mm wide, sparsely appressed hairy, green when immature (mature color unknown), apex beaked 1–4 mm long, rarely rounded, base rounded, sometimes with weak constrictions between seeds, pericarp <0.5 mm thick. Seeds 1–5 per monocarp, in a single row, discoid, 6–8 mm long, 5–7 mm wide, light brown, surface with pits.

Distribution.

Peninsular Malaysia, Sumatra, and Borneo (Brunei, Sabah, Sarawak, and Kalimantan) (Fig. 4).

Habitat and ecology.

Lowland dipterocarp forest, secondary forest, sometimes by streams, on sandstone-derived clay soils, rarely on ultramafic substrates, at 20–855 m elevation.

Phenology.

Flowers collected from March to November. Fruits collected from July to December.

Etymology.

The specific epithet honors Professor Richard Mark Kingsley Saunders, former professor at the University of Hong Kong, for his contribution to Annonaceae systematics, phylogeny, and pollination ecology.

Notes.

Van Heusden (1994) noted that Meiogyne cylindrocarpa specimens from Borneo and Sumatra differ from the New Guinea specimens in tree size, leaf shape, and flower size but dismissed these as infraspecific variation engendered by habitat, attributing the long caudate leaf apices of the Bornean and Sumatran specimens to a habitat with higher rainfall and concluding that “ the differences are not consistent enough to distinguish two species. ” However, several molecular phylogenetic studies have suggested that the West Malesian specimens should be regarded as a distinct species (Thomas et al. 2012; Xue et al. 2014, 2021; Jaikhamseub et al. 2022; Liu et al. 2025 d). The most densely sampled, well-resolved, and well-supported phylogeny of Liu et al. (2025 d) retrieved Meiogyne cylindrocarpa (as ‘ Meiogyne cylindrocarpa (Australia) ’) within the Australasia-Pacific clade, whereas Meiogyne saundersii (as ‘ Meiogyne cylindrocarpa (Borneo) ’) is nested within the early-divergent basal Asian grade (Fig. 1). Apart from the sharply defined differences mentioned in the diagnosis, Meiogyne saundersii also differs from M. cylindrocarpa in its monocarp length (10–17 mm long vs. typically 25–35 mm long, excluding stipe) and monocarp apex (typically contracted into a narrow beak 1–4 mm long, rarely rounded vs. typically rounded, rarely mucronately beaked up to 1.5 mm long). The habit of Meiogyne saundersii varies from treelets to trees up to 20 m tall, whereas Meiogyne cylindrocarpa varies from shrubs to treelets up to 6 m tall. Furthermore, the habitat and climatic niche occupied by the two species differ considerably, with M. saundersii occurring in tropical rainforests without a dry season and M. cylindrocarpa occupying forests and woodlands with a distinct dry season. The type of M. cylindrocarpa was collected from Merauke, a coastal area in Indonesian New Guinea with a pronounced dry season. Other specimens assessed to be conspecific were collected from East Java, the Lesser Sunda Islands, the Maluku Islands, southern coastal parts of New Guinea, the northern part of Western Australia, the northern part of the Northern Territory of Australia, the coastal areas of the Cape York Peninsula, and the Mariana Islands, all of which have a pronounced dry season, with the driest quarter receiving <300 mm rainfall. The geographic distribution of the two species seems sound, as many plant species are restricted to either wet tropics or seasonal tropics (Crisp et al. 2009). Philippine specimens were not included in the concept of Meiogyne cylindrocarpa in van Heusden (1994), but Turner (2016) reduced the Philippine Alphonsea sessiliflora Merr. to synonymy of M. cylindrocarpa. More work is needed to assess whether the Philippine name requires recombination in Meiogyne, owing to the scarcity of specimens available. Oncodostigma wilsonii Guillaumin from Vanuatu is regarded by van Heusden (1994) as a synonym of Meiogyne cylindrocarpa, but we consider the species distinct and transferred it to Meiogyne (see below). Apart from being confused with Meiogyne cylindrocarpa (e. g., Turner 2014), herbarium specimens of Meiogyne saundersii are frequently misidentified as Alphonsea, Polyalthia, and Xylopia species. The morphological differences between Meiogyne cylindrocarpa, Meiogyne saundersii, and two other species treated below are summarized in Table 1.

Preliminary conservation status.

The species is rather widespread, with its EOO and AOO estimated at 1,422,770 km 2 and 100 km 2, respectively. Moreover, it grows in several protected areas (IUCN Category II: Gunung Mulu National Park, Gunung Palung National Park; IUCN Category Ia: Andulau Forest Reserve, Tangkulap Forest Reserve, Sg Imbak Forest Reserve; IUCN Category VI: Bukit Belata Forest Reserve). Therefore, it is here assessed as Least Concern (LC).

Additional specimens examined.

Brunei • Belait: Liang, Andulau Forest Reserve (Sg Liang), Compt. 5, Sg Lumut, 4°38'31"N, 114°30'31"E, 38 m, 16 Aug 2011, Mhd Ariffin BRUN 23652 (BRUN). Indonesia • Pulow Bulit Tekemeng [Bukit Tekenang?] forest, 10 Oct 1949, Main (Expedition Polak) 2064 (L). West Kalimantan: Serawai, 3 km southwest of Nanga Jelundung, 0°29'43.5"S, 112°32'3.1"E, 120 m, 31 Oct 1995, Church et al. 2863 (K) • Ketapang, Gunung Palung National Park, Cabang Panti Research Site, Trail SC, 1°13'S, 110°6'E, 25 m, 9 Mar 1997, Laman TL 683 (K). East Kalimantan: • Agathis’ Hill, 2 nd summit, northwest of Camp Mului, 855 m, s. d., Raes et al. 706 b (L) • PT-ITCI, near camp Birawa jalan 5200, 491 m, 15 Jan 2002, Slik IT 83-3002 (L) • Berau, INHUTANI I area, near plot 4, 117°17.737'E, 2°05.471'N, 20 m, 3 Mar 1997, Goverse & Adriansyah Berau 463 (K, L). Central Kalimantan: • Kab. Kotawaringin Timur, km 5 from camp 48, 1°29'S, 112°31'E, c. 50 m, 21 Sep 1996, Argent & Wilkie 966 (K, L, SING) • Sintang HPH Km 68–70, 0°51'53.6"S, 112°13'29.9"E, 120 m, 16 Apr 1994, Church et al. 960 (K, SING). Sumatra: • East Coast, Asahan, Masihi Forest Reserve, Oct – Nov 1932, Krukoff 4170 (L, SING) • Archipel. Ind. Eil Simaloer bij Sumatra, Landschap Tapah, 16 Feb 1920, Achmad 1693 (L) • ibid., 16 Apr 1920, Achmad 1801 (L). Malaysia • Sarawak: 4 th Division, Gunong Mulu National Park, 530 m, 27 Sep 1976, Lee S 38066 (K, SAR, U). Sabah: • about 4 th mile of Ranau-Poring Road, 22 Jun 1957, Sinclair et al. 9277 (L, SING) • Lahad Datu, Danum Valley, s. d., Ridsdale DV-M 11930 (L) • Lahad Datu, Danum Valley and environs, s. d., Anonymous 1 / 1930 (SAN) • ibid., Anonymous R 3197 (SAN) • Lamag, Karamuak, Sg Korong, 500 ft, 6 Sep 1973, Leopold Madani SAN 76322 (K, L, SAN) • Sandakan, Segaliud Lokan, 11 Jul 1988, Julius et al. SAN 124229 (SAN) • Sandakan, Tangkulap Forest Reserve, 7 Dec 1985, Sigin et al. SAN 108019 (SAN) • Sipitang, 6 miles from Mandulang road to Maligan, 7 Sep 1983, Lee & Dewol SAN 69854 (K, L, SAN) • Telupid, Bukit Tawai Forest Reserve, near sawmill, 5°31'N, 117°04'E, 100 m, 10 Apr 1994, Mat Salleh & Zainuddin KMS 3440 (KEP, L, SAN) • Telupid, Bukit Tawai Forest Reserve, behind Golden Apex Sawmill, 10 Apr 1994, Zainuddin et al. 5007 (K, KEP, SAN) • Tongod, South of Sg Imbak Forest Reserve, 2 Jul 2000, Diwol Sundaling SAN 133028 (K, SAN, SAR, SING). Penang: • West Hill, 1888, Curtis s. n. (SING). Selangor: • Hulu Selangor, Bukit Belata Forest Reserve, survey trail parallel to main trunk road B 33, 3°34.06'N, 101°26.26'E, 59 m, 25 May 2016, Chew et al. FRI 73143 (KEP). Johor: • Mersing, 20 Sep 1994, Wiart & Teo KL 4405 (KEP).