Timonius stenolobus J.Chen & K.M.Wong, 2014

Chen, Junhao, Wong, Khoon Meng, Ent, Antony Van Der & Tan, Hugh T. W., 2014, Nine new species of Timonius (Rubiaceae) from Kinabalu Park, Borneo, Phytotaxa 181 (3), pp. 138-150 : 147-148

Timonius stenolobus J.Chen & K.M.Wong , sp. nov. ( Fig. 3H )

Similar to Timonius mutabilis ( Korthals 1851: 212) Walpers (1852: 765) , but differing by the calyx pubescence (sparsely pale-hairy vs. densely brown-hairy), mature fruit shape (narrowly ellipsoid vs. globose), and longer calyx lobes in flowers (5–7 mm vs. 1–3 mm long) and fruits (5–7 mm vs. 1.5–5 mm long).

Type: — BORNEO. Sabah: Kinabalu Park, Penibukan , forest trail above camp, 1220–1520 m, 10 January 1933 (♀ plant), Clemens & Clemens 30947 (holotype K; isotype L) .

Timonius polyneurus sensu Beaman & Anderson (2004: 348) , pro parte, non Valeton (1909: 59): quoad Clemens & Clemens 40867.

Timonius sp. 2 in Beaman & Anderson (2004: 349), pro parte, quoad Clemens & Clemens 30947, 31091, 50299.

Tree to 9 m tall; trunk dbh and bark unknown. Stipules narrowly triangular to lanceolate, with two lateral ridges converging at the apex, imbricate. Leaves opposite; petioles 3–12 mm long, 1–2 mm in diam.; blades elliptic, 5.6– 14.5(–19) × 1.9–4.8(–6.5) cm, base cuneate, apex cuspidate, margins plane; chartaceous, lower surface sparsely appressed-pubescent on the midrib and secondary veins, subglabrous to sparsely appressed-pubescent on the lamina, upper surface plane (not bullate); secondary veins 4–8 on each side of the midrib, 5–23 mm apart from each other; tertiary veins not prominent on lower surface. Inflorescences: female plants with a solitary flower per inflorescence, peduncles 0.6–1.1 cm long, peduncular bracts whisker-like, 2.5–3 × ca. 0.5 mm; male plants with up to 3 flowers per inflorescence, peduncles 1–1.2 cm long. Calyx lobes in female flowers 4, linear (length more than thrice the basal width), 5–6 mm long, sparsely pubescent outside; in male flowers 4, linear, 5–7 mm long, sparsely pubescent outside. Corolla unknown. Fruits narrowly ellipsoid, ca. 3 mm in diam., ca. 7 mm long, subglabrous; peduncles ca. 1.4 cm long, subglabrous; persistent calyx lobes linear, 5–7 mm long.

Etymology:—The specific epithet refers to the narrow calyx lobes of this species.

Distribution: —Probably endemic to Kinabalu Park.

Habitat: —Lower montane forest, on ultramafic substrates.

Proposed conservation status: —The conservation status assessed for T. stenolobus using GeoCat was ‘Near Threatened’ ( IUCN 2001).Although its estimated EOO (113 km 2) and AOO (20 km 2) are within the ‘Endangered’ range, there is no evidence of decline or fluctuations in EOO, AOO, number of locations, and number of mature individuals. Furthermore, the known populations are protected within the boundaries of Kinabalu Park. Nevertheless, the extreme localisation of this species suggests that the known populations may be particularly susceptible to stochastic variation in the environment, such as forest fires, droughts and climate change.

Additional specimens examined (paratypes): — BORNEO. Sabah: Kinabalu Park, Marai Parai , 1520–1830 m, 5 April 1933 (♀ plant), Clemens & Clemens 32521 (BO, L); Penataran basin, 1980 m, 31August 1933 (♀ plant), Clemens & Clemens 40171 (BO, L); Penibukan, 1220–1520 m, 16 January 1933 (♀ plant), Clemens & Clemens 31091 (L), 16 January 1933 (♀ & ♂ plants), 31091 (K), 1220 m, 25 October 1933 (♀ plant), 40867 (K, L), 1370 m, 11 November 1933 (♀ plant), 50299 (L), 11 November 1933 (♀ & ♂ plants), 50299 (K) .

Notes: —Material of this species is frequently infected with galls that superficially resemble stalked fruits and arise from leaf axils. The leaves are pale to medium-brown when dry.

Figures

FIGURE 3. A. Solitary fruit of Timonius kinabaluensis, Amin SAN 115990 (SAN). B. Solitary fruits of T. ophioliticus, Leopold SAN 81740 (L). C. Male inflorescences of T. ophioliticus, Muin SAN 31658 (SING). D. Strongly recurved leaf margins of T. tambuyukonensis, Van der Ent et al. SNP 24479 (SNP). E. Solitary female flowers of T. tambuyukonensis, Van der Ent et al. SNP 24479 (SNP). F. Stipules and female inflorescence of T. clementis, Wong & Kambira WKM 2410 (L). G. Solitary fruit of T. tambuyukonensis, Van der Ent et al. SNP 24479 (SNP). H. Solitary fruit of T. stenolobus, Clemens & Clemens 40171 (L). Scale bars: 1 cm. [Photos:A and C, J. Chen; B, F, and H, K.M. Wong; D, E, and G, A. van der Ent]