Chassalia muluensis T.Y.Yu, 2021

Yu, Tian Yi, Turner, Ian M. & Cheek, Martin, 2021, Revision of Chassalia (Rubiaceae-Rubioideae-Palicoureeae) in Borneo, with 14 new species, European Journal of Taxonomy 738, pp. 1-60 : 43-46

Chassalia muluensis T.Y.Yu sp. nov.

urn:lsid:ipni.org:names:77215412-1

Figs 24–25

Diagnosis

Differs from other Bornean species of Chassalia by having secondary nerves densely distributed, 16–18 on each side of the midrib; stipule broadly flabellate, 5–8 × 5–12 mm; inflorescence 9.5–14 cm long, longer than the average leaf, but usually shorter than the longest leaf; only found in Gunung Mulu National Park.

Etymology

The epithet alludes to Gunung Mulu National Park to which this species is endemic.

Type

MALAYSIA – Borneo, Sarawak • Gunung Mulu National Park, west ridge just below Camp 4; 4°03′ N, 114°53′ E; alt. 1600 m; submontane ridge forest; 29 Apr. 1978; fl.; G. Argent, B. Coppins 1134; holotype: K [ K001129717 ]!; isotype: KEP [ KEP271647 ] .

Additional material

MALAYSIA – Borneo, Sarawak • Gunong Mulu National Park, ridge west of Camp 4; 4°05′ N, 114°55′ E; alt. 1850 m; 25 Mar. 1978; fl.; I. Nielsen 856; K!, AAU • Camp 4; 114°54′ E, 4°05′ N; alt. 1800 m; slope in moss forest in upper montane forest; 22 Mar. 1978; fl.; Carlo Hansen 544; K !.

Description

Subshrub, shrub or sub-woody epiphyte, 0.75–2 m high, glabrous. Stem terete, 3–4 mm wide. Internodes of the flowering branch 1–3 cm long, lower internode terete, upper internode usually drying flattened, canaliculate, broadening at apex, base 2–4 mm wide, apex 3–5 mm wide. Leaves opposite, decussate. Leaf-blades elliptic, 6.5–14.5 × 3–5.8 cm; apex acute to acuminate, acumen 5–15 mm long; base attenuate; midrib slightly raised above, domatia absent; secondary nerves 16–18 on each side of the midrib, prominent above; tertiary nerves not visible. Petiole flattened, canaliculate, 3–4 cm × 1–2 mm. Stipule not sheathing, flabellate, 5–8 × 5–12 mm, apex breaking very easily, base drying deep brown, margin light brown. Inflorescence a compound cyme, 9.5–14 cm long, peduncle 6.5–8 cm long, bracts of first internode of rachis narrowly elliptic, 2–4, 9–12 × 3–6 mm, first internode of rachis and first branches 1.5–3 cm long, bracts of second internode of rachis and second branches 4, ovate to elliptic, 10 × 5 mm, bracts of capitulum 5–6, narrowly elliptic, 5–10 × 2–5 mm, second internode of rachis and second branches 5–10 mm long or absent. Flowers 12–18 in each capitulum, hypanthium 2 × 2–3 mm, calyx tube 1–1.2 × 1.5 mm, lobes of calyx tube 0.3 × 0.3–0.5 mm, corolla tube 8–12 × 3–4 mm, inside corolla tube a band of hairs 0.5 mm wide at base of stamens, 3 mm from mouth of corolla tube, hairs erect, colourless, 0.1–0.2 mm long; corolla lobes 2 × 2–3 mm, stamens 2.5 × 0.5 mm, filament 0.5 × 0.1 mm, style ca 1.5 times as long as corolla, 1.8 cm long. Disc cylindric, 0.7 × 0.9 mm. Fruits ellipsoid, dark purple when ripe, 7.5–8 × 4–5.5 × 4–5.5 mm, pyrenes plano-convex, dorsal surface convex, with two adjacent parallel longitudinal crests, each 0.2 mm wide, curved, 0.2 mm apart along their length, forming a longitudinal groove from apex to base between the two crests; ventral surface concave, centre slightly elevated, margin with an endocarpal outgrowth 0.4–0.5 mm wide and a groove between the edge of endocarp and endocarpal outgrowth 0.2–0.3 mm wide. Raphal opening at base of the endocarpal outgrowth, round, 0.3 mm diameter, 0.2 mm from the edge of the pyrene wall, apex with a bony spine, erect, 1 × 0.2 mm. PGS not detected. Seeds brown, hemi-ellipsoid, slightly crested at central part of dorsal side, 3.2 × 0.6 mm.

Distribution, habitat

Borneo: Malaysia, Sarawak, Gunung Mulu National Park, around Camp 4. Slope in moss forest in upper sub-montane to montane forest, alt. 1600–1850 m.

Figures

Fig. 24. Chassalia muluensis T.Y.Yu sp. nov. A. Flowering shoot. B. Flower. C. Longitudinal view of corolla tube showing stamens, band of hairs, style and disc. D. Hypanthium, calyx and disc of a flower. E. Pyrene ventral surface. F. Dry fruit transection. G. Part of infructescence, showing dry fruit. From G. Argent, B. Coppins 1134. Drawn by T.Y. Yu.

Fig. 25. Holotype of Chassalia muluensis T.Y.Yu sp. nov. (G. Argent, B. Coppins 1134).