Serawaia J.Compton & Schrire, 2019

Compton, James A., Schrire, Brian D., Koenyves 3, Kalman, Forest, Felix, Malakasi, Panagiota, Sawai Mattapha, & Sirichamorn, Yotsawate, 2019, The Callerya Group redefined and Tribe Wisterieae (Fabaceae) emended based on morphology and data from nuclear and chloroplast DNA sequences, PhytoKeys 125, pp. 1-112 : 50-51

8. Serawaia J.Compton & Schrire gen. nov.

Diagnosis.

This monospecific genus has several autapomorphies compared with other genera within the tribe. It is the only species that has large and very persistent imbricate floral bracts along the inflorescence enclosing the uniquely golden-yellow flowers. Serawaia is the only genus in Clade D that has prominent gibbosities below the stipules. Its nearest affinities lie with Callerya , Kanburia and Whitfordiodendron which all have sericeous backs to their standard petals. The back of the standards of Serawaia are, however, pubescent but the hairs are not as long as those in Afgekia , the other member of Clade D. The wing petals, which are free from the keel, almost equal the length of the keel as in Kanburia , Whitfordiodendron and Afgekia which distinguishes these four genera readily from Callerya whose wings are shorter. The ovary in Serawaia is only sparsely hairy whereas in all four other genera within Clade D the ovaries are densely sericeous (see figs 4 and 5 in Schot (1994: 33, 34).

Type species.

Serawaia strobilifera (Schot) J.Compton & Schrire ≡ Callerya strobilifera Schot.

Genus description.

Scandent twining vines scrambling up trees and along river banks to 8 m high. Stems very pale grey or white, terete, glabrous. Leaves with 5-7 leaflets, evergreen, glabrous, imparipinnate, rachis 7-20 cm long. Stipules 5-8 mm long, linear, persistent, arising from above prominent gibbosities. Stipels 3-4 mm long, linear, persistent. Leaflets 4-14 × 2-7 cm, broadly or narrowly elliptic, glabrous on both surfaces, apex acuminate or cuspidate, margins entire, base rounded to subcordate. Inflorescence erect, sometimes leafy few-branched panicles 12-20 cm long, peduncle pale grey, glabrous. Flowers 15-21 mm long, emerging from May to August. Floral bracts 15-18 × 8-12 mm, persistent, with longitudinal parallel venation, overlapping flower buds in a strobilate inflorescence. Bracteoles 6-7 mm long, at top of pedicel, linear, persistent. Pedicels 4-6 mm long, glabrous. Calyx 3-6 × 4-6 mm campanulate, oblique, pubescent externally, five lobed, teeth distinctly unequal 2-6 mm long, acute, ciliate. Standard 15-18 × 11-17 mm, suborbicular, bright lemon or golden yellow, nectar guide yellow, back of standard sparsely pubescent, apex retuse, callosities of boss type. Wing petals 12-14 × 4-5 mm, glabrous, subequal to the keel, each semi-pandurate, slightly curved upwards at the apex; completely free from the keel, apex obtuse, basal claw 2-3 mm long. Keel petals 11-13 × 4-5 mm, glabrous, united into a falcate, navicular cup, apex obtuse, basal claw 3-4 mm long. Stamens diadelphous, nine fused together, the vexillary one free, all curved upwards at apex. Ovary sparsely pubescent, style glabrous, 2-3 mm long curved upwards at apex, stigma punctate. Pods 19-30 × 2-2.5 cm, flat, linear, or obovate, dehiscent, surface shortly hirsute, smooth, brown and hard when dry, subseptate. Seeds 2-3, flattened-orbicular, 17 × 17 × 10 mm, hilum central, elliptic 2-3 × 1 mm.

Etymology.

named after the Serawai river in west Kalimantan, a tributary of the Kapuas river, where the species was first discovered.