Lasianthus hirtus Ridl.

Zhu, H., Roos, M. C. & Ridsdale, C. E., 2012, A taxonomic revision of the Malesian species of Lasianthus (Rubiaceae), Blumea 57 (1), pp. 1-102 : 48

58. Lasianthus hirtus Ridl.

Lasianthus hirtus Ridl. (1909) 36; (1923a) 153. —

Type: Ridley 14009 ( holo SING; iso K), Peninsular Malaysia, Pahan.

Lasianthus acutatus auct non Miq.: Bakh.f. (1965) 341.

Shrubs, 2 m high; branchlets terete, c. 2 mm diam, densely spreading brown-pilose. Leaves: blades oblong-lanceolate, 6 – 9 by 2 – 2.5 cm, thinly coriaceous, densely pilose on both surfaces, apex caudate to caudate-acuminate, base acute to subrounded, midrib and nerves depressed above, prominent beneath, nerves 8–9 pairs, ascending at an angle of c. 50°, curved to the margin, nervules obscure above, distinct beneath, subparallel; petioles 2–4 mm long, densely spreading brown-pilose. Stipules ovate, 3–4 mm long, membranaceous, densely pilose. Cymes sessile; bracts absent. Flowers sessile; calyx campanulate, dense pilose, tube c. 1 mm long, lobes 5, subulate-lanceolate, c. 1.5 mm long, densely long-pilose; corolla c. 7–8 mm long, pilose outside, lobes 5, lanceolate. Drupes ellipsoid, c. 4 mm long, sparsely pilose to densely pilose, with 5 obtuse ridges, crowned by densely pilose calyx limbs; pyrenes 4, smooth on the abaxial face.

Distribution — Peninsular Malaysia, Indonesia ( Sumatra, Java, Sulawesi).

Notes — This species is close to L. acutatus but differs from it by having dense spreading pilose hairs on branches, leaves, petioles, stipules and calyx; leaves relatively small ( 6– 9 cm long); stipules ovate. Lasianthus acutatus has stiff hairs on branches, leaves, and stipules, relatively bigger leaves that are 12–17 cm long, linear-lanceolate stipules.

Lasianthus hirtus has ovate and membranaceous stipules, the same as L. stercorarius , but differs from the latter by having dense spreading pilose hairs on branches, leaves, petioles, stipules, and calyx; calyx with 5 subulate-lanceolate lobes; drupes with 5 pyrenes.

Lasianthus hirtus was reduced to a synonym of L. pilosus by Wong (1989). However, it conspicuously differs from L. pilosus by having leaf blades relatively small ( 6– 9 cm long) and with less nerves and acute to subrounded base; stipules ovate; bracts absent; calyx lobes subulate-lanceolate, relatively short, c. 1.5 mm long. Lasianthus pilosus has leaves relatively large ( 10–17 cm long) with usually rounded unequal base and more nerves; stipules triangular-lanceolate; bracts subulate; calyx lobes filiform, relatively long.

Lasianthus hirtus could be conspecific to L. rufus (Korth.) Miq. , because it almost agrees with Korthals’ (1851) description. Without seeing type specimens of L. rufus , we still treat L. hirtus separately.