Urophyllum species

Wong, Khoon Meng, 2018, Flora of Singapore Precursors, 11. A new species of Urophyllum (Rubiaceae) from the Malay Peninsula, Phytotaxa 373 (3), pp. 236-240 : 237-239

A new Urophyllum species from the Malay Peninsula

During our revision of the genus for the new Flora of Singapore project, the species previously identified by Wong (1988, 1989) only as “ Urophyllum sp. 10” has required re-analysis, as it occurs in Singapore. After comparison with all taxa enumerated in Maschalocorymbus and Pleiocarpidia by Bremekamp (1940a, b), and Urophyllum trifurcum which also has trichotomously branched inflorescences, as well as type specimens from the A, BR, K, L, and SING herbaria (acronyms follow Thiers, 2018), “ Urophyllum sp. 10” of Wong (1988, 1989) could be verified as being unnamed. Apparently, from the specimen sheets known, Bremekamp has not seen any of the collections of this species. We have also looked through more recent collections of this group from around the region in holdings at the BKF, BO, KEP, SAN, SAR and SING herbaria for possible records of occurrences elsewhere in the vicinity of the Malay Peninsula. This “sp. 10” superficially most resembles Urophyllum trifurcum in its leaf venation and trichotomously branched inflorescences ( Fig. 1 ). Below, we describe this as a new species endemic to the Malay Peninsula.

Urophyllum malayense K.M.Wong , sp. nov.

Similar to Urophyllum trifurcum but differing in the inflorescences having many (more than 10) flowers per ultimate cluster on the main branches, and much smaller flowers with calyx of 1–1.5 mm diameter (with distinctly triangular lobes in the male flower 0.2–0.3 mm long and in the female ca. 0.5 mm long) and corolla lobes ca. 1 mm long. In contrast, U. trifurcum has inflorescences with fewer ((1–)3–8) flowers per ultimate cluster, and larger flowers of both sexes with subtruncate calyx of 4–5 mm diameter and corolla lobes 2.5–3 mm long.

Type:— SINGAPORE. MacRitchie Reservoir, east end, 16 Jan 1949 (♂), J. Sinclair SFN 37937 (holotype SING [barcode SING 0030791]).

Treelet to small tree up to ca. 10 m tall; stem bark smooth, green at a young stage becoming grey-brown to red-brown; twigs glabrous. Stipules linear to ovate or elliptic, entire, 6–17 mm × (3.5–) 6.5–9 mm, glabrous, caducous at nodes proximal to the newly developed leaves. Leaves elliptic, (8–)16–23.5 × (3.5–) 7–11.5 cm, apex acute to obtuse and with an abruptly attenuated cusp to 10(–15) mm long and 1–2 mm wide, base broadly cuneate to rounded; midrib flat to slightly channeled on upper surface, prominent on lower surface, secondary veins 9–11 pairs, flat to impressed on upper surface, prominent on lower surface, tertiary veins scalariform with lax reticulations in between; upper surface glabrous, lower surface glabrous except for occasional scattered (microscopic) fine appressed hairs on midrib and secondary veins; petioles 8–15 mm long. Inflorescence of similar form between male and female plants, in general appearance a trichotomously branched structure with a distinct peduncle (1.7–) 3–4.5 cm long and with scattered fine pale appressed hairs; rachis (main or central axis) 4–9(–13) mm long, with a reduced stipule-like bract between the first branches, the lower two primary branches 6–15 mm long, an upper pair of shorter primary branches often also developed, these branches typically terminating in closely set and inconspicuous condensed axes branching to a further 1–2 orders and bearing subumbellate ultimate clusters of many (more than 10) flowers each; the rachis and branches all covered in dense short suberect brown hairs. Flowers on pedicels 1–2(–4) mm long and densely suberect brown hairy; calyx in the male dish-like, 0.5 mm long, 1–1.5 mm in diameter, without conspicuous hypanthium and with triangular lobes 0.2–0.3 mm long, in the female with cup-like hypanthium, 0.7–1 mm long, 1–1.5 mm in diameter and with triangular lobes ca. 0.5 mm long, in both sexes with dense pale brown suberect minute hairs on the outside; corolla in both sexes with tube ca. 1 mm long and sparsely to densely covered with pale or brownish minute suberect hairs on the outside, lobes 5, each ca. 1 mm long and sparsely to densely covered with pale or brownish minute suberect hairs on both surfaces, throat congested with pale stiff uniseriate multicellular hairs ca. 1 mm long, these hairs occasionally with tips constricted between cells and appearing sub-moniliform; stamens 5, with inconspicuous filaments inserted between corolla lobes and at the throat, exserted, in the male ca. 1 mm long, ca. 0.3–0.4 mm wide, bearing pollen, in the female ca. 0.8 mm long, ca. 0.2 mm wide, empty; ovary in the male degenerate, in the female well-developed within hypanthium; disk 5–10-lobed; style in the male rudimentary and less than 0.5 mm long, in the female 1.5–2 mm long, exserted; stigmas in the male not formed, in the female with 5 narrow spreading lobes ca. 0.5 mm long, exserted above the level of the corolla throat hairs. Fruits subglobose and often slightly 5-lobed, to 4–6 mm diameter, apex with broad circular scar or remains of the calyx limb surrounding the remains of the shrivelled disk; pedicels 4–8 mm long.

Notes:—Corner (in SFN 30167) noted that the female calyx is green, the corolla pale green, and the style and stigmas white. Sinclair (in SFN 37937) recorded that the male petals are white (but this is probably an impression contributed by the white corolla throat hairs and pale hairs over the inner corolla lobe surfaces, which retain their color even after drying). The fruits are generally noted as yellowish green when fresh.

Etymology:—The specific epithet refers to the Malay Peninsula.

Distribution:—As far as is known, Urophyllum malayense is endemic to Peninsular Malaysia, documented for the states of Trengganu, Pahang and Johor, and Singapore.

Habitat:—Lowland rain forest understory.

Proposed conservation status:—Documentation of the species has come from scattered collections made across lowland forest areas, much of which have been impacted by logging or land-use changes, both of which are highly detrimental to many understory plant species, including, in our casual experience, those in Urophyllum . It has not been recorded for most states in Peninsular Malaysia and in the few states where it has been known to occur, much land-use changes have taken place over the last decades. There are no detailed population studies. According to guidelines by IUCN (2012), we suspect that population size could be irreversibly reduced by as much as 50% in the last three decades, so that a conservation status of Endangered (EN) may be suitable.

Additional specimens examined (paratypes):—PENINSULAR MALAYSIA. Johore: Bandar Tenggara, Linggiu- Sindora Forest , 25 Jul 1991 (fruit), T. Lesmy FRI 35939 ( KEP, SING) ; Bukit Tinjau Laut , 5 Aug 1939 (♂), E. J. H. Corner s.n. ( SING) ; Castlewood, Sungai Tebrau , Mar 1898 (fruit), H. N. Ridley s.n. ( SING) ; Kluang, path to Gunong Blumut , 23 Sep 1970 (fruit), Mohd. Shah & Sanusi MS 2142 ( SING) ; Sungai Sedili, 26 Jul 1939 (♀), Ngadiman SFN 36870 ( SING). Pahang: Gunong Tapis , 1700 ft elev., 29 Sep 1971 (♀), Y. C. Chan FRI 19874 ( KEP, SING) ; Kuantan, Baloh Forest Reserve, 27 Jul 1966 (♂), Rahim Ismail KEP 97926 ( KEP, SING), Kuantan, Sungai Lembing , 10 Jun 1934 (♂), C. F. Symington & Kiah SFN 28760 ( SING) ; Lepar, Lepar Forest Reserve, 17 Jun 1967 (♀), T. Suppiah KEP 104999 ( KEP, SING). Trengganu : Dungun , Bukit Bauk Forest Reserve , 4 Sep 1966 (fruit), Rahim Ismail KEP 98939 ( KEP, SING), Dungun , Jengai Forest Reserve , 91 m [298 ft] elev., 6 Jul 2010 (♀), C. L. Lim FRI 72846 ( KEP, SING) ; Kemaman, Bukit Kajang, 500 ft elev., 12 Nov 1935 (♂), E. J. H. Corner SFN 30425 ( SING), Kemaman, Ulu Bendong , 2 Mar 1935 (♀), E. J. H. Corner SFN 30167 ( SING) .

SINGAPORE: Changi , 19 May 1891 (♂), H. N. Ridley 4892 ( SING) ; MacRitchie Reservoir , 30 Jun 1976 (♂), M. Shah & M. Ali MS 3873 ( SING), MacRitchie Reservoir, Lornie Trail, 6 Sep 2015 (♂), Y. S. Yeoh YYS 16 ( SING) .

Figures

FIGURE 1. Leaf venation, inflorescence form and flowers compared for male specimens of Urophyllum malayense (A & C, from the holotype J. Sinclair SFN 37937 at SING) and U. trifurcum (B & D, from the lectotype H.N. Ridley 1180 at SING). Scale bar of 1 cm applies to all images.