Chassalia involucrata T.Y.Yu, 2021

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 : 23-26

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scientific name

Chassalia involucrata T.Y.Yu

sp. nov.

Chassalia involucrata T.Y.Yu sp. nov. Fig. 12–13 View Fig View Fig


Differs from other species of Chassalia in Borneo in having large leaves up to 48 cm long and 15 cm wide (they are much smaller in other species), in the capitulum having outer and inner bracts up to 1.5 cm wide (broader than in any other species), in the infructescences usually persisting for a whole season until new inflorescences are produced (not soon disappearing after fruit maturity). Most similar to, but differing from, C. calamus sp. nov. in having bracts usually longer than the flower bud (not shorter), in having a longer peduncle, in having bigger leaves (to 48 × 12 cm, not to 33 × 12 cm) and more secondary veins (up to 26 on each side of the midrib, not <18), and in having longer (4–14 cm, not <5 cm) petioles.


The epithet alludes to the involucrate bracts of rachis and capitulum, which are larger and more conspicuous than in other species of the genus in Borneo.


BRUNEI • Temburong district, Kuala Belalong, Batu Apoi Forest Reserve, at the Sungai Engkiang River, towards the Sungai Belalong, below Pondok Engkiang; 115°09′ E, 4°33′ N; 22 Nov. 1991; Carlo Hansen 1608; holotype: K [ K001129724 ] GoogleMaps !.

Additional material

BRUNEI • S. Belalong below Kuala Ropan; 11 Feb. 1959; P.S. Ashton BRUN 5227 View Materials ; BRUN, K!, SING!, BRUN Temburong District, LZ 298, beside the Temburong River; 19 Sep. 1988; W. K. Wong WKM 484; K!, SING !.

MALAYSIA – Borneo , Sabah • Tambunan District, Crocker Range, Km 64 on Kota Kinabalu – Tambunan Road; 5°46′ N, 116°21′ W; alt. 1250 m; 11 Oct. 1983; John Beaman 7268; K!, MSC, UKMS. GoogleMaps Borneo , Sarawak • Kuching District, 12 th mile Penrissen Road; 19 Sep. 1966; Banyeng ak Nudong et Benang ak Bubong, S 25474 View Materials ; A, BO, K!, L, SAN, SING, SAN, A, BO GoogleMaps Nanga Segera Base Camp, Ulu Engkari , Lanjak Entimau , Wildlife Sanctuary ; 4 Jun. 1998; Kit Pearce, Awg Enjah S 78122 View Materials ; K!, KEP, L .


Herb, semi-woody shrub to small tree, 1–4 m tall, glabrous. Stem strong and thick, 0.5–0.7 cm wide, slightly hollowed or not. Internodes 3–13.5 cm long, thick, sometimes slightly canaliculate, slightly broadening at apex. Stipules big, flabellate, 1–1.5 × 1–2 cm, base usually divided into 2 parts. Leafblades large, broadly elliptic, 13–36 × 6–15 cm, midrib slightly raised both abaxially and adaxially, secondary veins 14–26 on each side, apex acuminate, acumen 5–18 mm long, base cuneate or attenuate, petiole long, 4–14 cm × 1.5–3 mm. Peduncle (5–)20–25 × 1.5–3 mm, bracts of rachis and first branches 2, opposite, usually connate to half the length, each bract 1.5–2 × 1–1.2 cm, sheath 0.5–0.7 × 2 cm, rachis and secondary branches very short to absent, 2–6 mm long, bracts of secondary branches 2, not sheathing, 12–15 × 10–12 mm, bracts of each capitulum elliptic, 8–12 × 5–10 mm. Flowers sessile in each capitulum, 16 mm long. Hypanthium 2 × 0.5 mm, calyx tube 0.5 × 1.3 mm, calyx lobes broadly triangular, 0.2 × 0.5 mm. Corolla tube 20 × 1 mm, broadening to 3 mm from midway, glabrous except inside corolla tube a band of hairs 2 mm wide at base of stamens, 7 mm from mouth of corolla tube, hairs erect, colourless, 0.1–0.2 mm long; corolla lobes 5, triangular, 4.5 × 2 mm. Stamens 2.5 mm long, slightly concave, base bifurcate, inserted 2 mm from mouth of corolla, filaments very short and broad, less than 0.1 mm long. Style probably exserted, stigma bilobed, lobes orbiculate, 1 × 0.8 mm. Disc cylindric, 1 × 1 mm, apex flat. Fruit sessile, ellipsoid, 7 × 5 × 4 mm, ripening blue, calyx persistent, not accrescent, 0.5 × 1.5 mm, disc persistent, not accrescent, 0.7 × 0.7 mm. Pyrene plano-convex, 6 × 5 × 2 mm, dorsal surface convex, with two adjacent parallel longitudinal crests, 0.4 mm wide, 0.4 mm apart along their length, forming a longitudinal groove from apex to base between the two crests; ventral surface concave, central part slightly elevated, margin with an endocarpal outgrowth 0.5–0.8 mm wide, with a groove between the edge of endocarp and endocarpal outgrowth 0.2 mm wide. Raphal opening at base of the endocarpal outgrowth, round, 0.1 mm in diameter, 0.5 mm from the edge of the pyrene wall, apex with a bony spine, spine triangular, erect, 0.5 × 0.2 mm. PGS not detected. Seed light brown, hemi-ellipsoid, 0.5 × 5 mm, longitudinally slightly crested at midline of dorsal surface, endosperm not detected.

Distribution, habitat

Borneo: Malaysia, Sarawak, Sabah; Brunei. River banks in lowland forest, alt. 100–350(–1250) m.


Sudan, Khartoum, University of Khartoum, Sudan Natural History Museum


Royal Botanic Gardens


Brunei Forestry Centre


Singapore Botanic Gardens


Naturhistorisches Museum Wien


Michigan State University


Sudan Natural History Museum


Harvard University - Arnold Arboretum


Herbarium Bogoriense


Nationaal Herbarium Nederland, Leiden University branch


Forest Research Centre


Forest Research Institute Malaysia