Dissochaeta axillaris Cogn. in H.J.P.Winkl., Bot. Jahrb. Syst. 48: 108. 1913.

Kartonegoro, Abdulrokhman, Veldkamp, Jan Frits, Hovenkamp, Peter & Welzen, Peter van, 2018, A revision of Dissochaeta (Melastomataceae, Dissochaeteae), PhytoKeys 107, pp. 1-178 : 1

6. Dissochaeta axillaris Cogn. in H.J.P.Winkl., Bot. Jahrb. Syst. 48: 108. 1913. Map 4

Dissochaeta ramosii Merr., J. Straits Branch Roy. Asiat. Soc. 86: 340. 1922. Type: Malaysia. Borneo, Sabah, Sebuga near Sandakan, Dec 1920, M. Ramos BS 1758 (lectotype, designated here: PNH [PNH32282, image seen]!; isolectotypes: A [A00072206, image seen]!, K [K000859509]!, US [US00120531, image seen]!).

Dissocaheta acmura auct. non Stapf & M.L.Green: Bakh. f., Contr. Melastom.: 227. 1943. p.p., excl. type.

Type.

Indonesia. Central Kalimantan: Semurung, Sungei Tarik, 18 Jul 1908, H.J.P. Winkler 3033 (lectotype, designated here: L [L0652534]!; isolectotypes: BM [BM00094485]!, BO!, BR [BR-518825, image seen]!, K [K000859508]!, WRSL n.v.).

Description.

Climbing up to 15 m in height. Branchlets terete, 4-5 mm in diameter, covered with brown stellate-tomentose hairs; nodes swollen, with interpetiolar ridges; internodes 6-9 cm long. Leaves: petioles terete, 9-18 mm long, densely stellate-tomentose; blades ovate or ovate-elliptic, 9-20 × 4-8.7 cm, subcoriaceous, base rounded, margin entire, apex acuminate, tip up to 1 cm long; nervation with 1 pair of lateral nerves and 1 pair of intramarginal nerves; adaxially glabrous, abaxially densely stellate-tomentose. Inflorescences axillary, up to 9 cm long, 15-20 flowers; main axes densely stellate-tomentose; primary axes 4-11 cm long with 2 or 3 nodes, secondary axes 1-4.5 cm long with 1 or 2 nodes, tertiary axes ca. 1.5 cm long with 1 node or not developed; bracts linear, ca. 5 mm long, stellate-tomentose, caducous; bracteoles linear, 3-4 mm long, stellate-tomentose, caducous; pedicels densely stellate-tomentose, 4-5 mm long in central flowers, 1-2 mm long in lateral flowers. Hypanthium campanulate, 8-10 mm × ca. 6 mm, densely covered with stellate-tomentose hairs, sometimes with capitate bristles; calyx lobes truncate, without distinct tip, ca. 1.5 mm long, sometimes with 4 minute acute tips; petal bud conical, 5-10 mm long mature petals ovate to suborbicular, 15-20 × 10-20 mm, base clawed, apex rounded, glabrous, white or pinkish white. Stamens 8, unequal, filaments curved sideways; alternipetalous stamens with 10-11 mm long filaments, anthers curved, sickle-shaped, thecae ca. 10 mm long, apex rostrate, pedoconnective ca. 5 mm long, basal crest erose, ca. 1 mm long, lateral appendages paired, filiform, 5-10 mm long; oppositipetalous stamens with ca. 10 mm long filaments, anthers S-shaped, thecae 10-12 mm long, basal crest ligular, ca. 0.5 mm long, sometimes with a pair of capillary appendages, ca. 1 mm long, lateral appendages paired, filiform, 7-8 mm long. Ovary ¾ of hypanthium in length, apex villous; style glabrous, curved at tip, 10-12 mm long; stigma minute; extra-ovarial chambers 8, extending almost to the base of the ovary. Fruits urceolate, ca. 15 × 12 mm, sparsely covered with stellate hairs or glabrous; calyx remnant truncate, persistent. Seeds ca. 0.75 mm long.

Distribution.

Borneo and Philippines (South-western Islands).

Ecology and habitat.

Primary open lowland forest or on limestone at 10-930 m elevation.

Vernacular name.

Borneo: rinsim (Kinabatangan).

Note.

Dissochaeta axillaris is easy to distinguish from all other species by its tomentose indumentum and axillary inflorescences. Differences with D. acmura , another species with axillary inflorescences species, are the more subcoriaceous leaf blades and the small petal buds which are sunken inside the calyx lobes. The distribution of those two species does not overlap. Sometimes this species is misidentified as D. annulata , which has leaf blades with a subcordate base and terminal inflorescences.

Selected specimens examined.

MALAYSIA. Sabah: Beluran, Bidu-Bidu Forest Reserve, 1 Mar 1991, Maikin & Lideh SAN 131046 (L); Bongol, 365 m, G.D. Haviland 1385 (K); Sandakan, Long Manis, 9 Aug 1962, G. Mikil SAN 31570 (BO, K, L); Ibid., Myburgh, Oct-Dec 1921, A.D.E. Elmer 20106 (BM, BO, K, L, P, U); Ibid., Kabili-Sepilok FR., 26 Jun 1937, Enggoh BNB 7270 (K, L); Ibid., Sebuga, M. Ramos BS 1758 (K, PNH); Beluran, Bongaya FR, 45 m, 17 Jul 1975, Aban & Kodoh SAN 81978 (K, L); Lahad Datu, Danum Valley, 22 Jul 1986, Leopold et al. SAN 114565 (K, L). INDONESIA. Central Kalimantan: Semurung, Sungai Tarik, 18 Jul 1908, H.J.P. Winkler 3033 (BM, BO, BR, K, L). East Kalimantan: Samarinda, Loa Haur, 60 m, 12 May 1952, A.J.G.H. Kostermans 6846 (BO, K, L, PNH); East Kutai, Sungai Susuk Region, 26 Jun 1951, A.J.G.H. Kostermans 5452 (BO, K, L); West Bengalon, Sebongkok Utara, 102 m, 6 Apr 1996, Ambriansyah & Arbainsyah AA 1667 (BO, K, L, P); Samboja, 50 m, 6 Jul 1995, Ambriansyah et al. AA 1280 (K, L, P); Sangkulirang, Mangapu, 10 m, 19 Jun 1937, Aet 739 (BO, L); Sebulu, 50 m, 1 Dec 1980, M. Kato & H. Wiriadinata B-6995 (BO, L). West Kalimantan: Ketapang, Gunung Palung National Park, Cabang Panti, 930 m, 20 Oct 1997, T.G. Laman et al. 1357 (BO, K). PHILIPPINES. Basilan: Nov 1912, D.P. Miranda FB 17872 (BM, K, L, P). Mindanao: St. Cruz Island, Sapamoro, 20 Dec 1961, Olsen 989 (L). Sulu: Jolo, Mt. Daho, Sep 1924, M. Ramos & G.E. Edano BS 43902 (L, P).

Figures

Map 4. Distribution of D. axillaris (●).