Dalbergia matthewii S. Soosairaj, P. Raja & S. John Britto, 2018

Soosairaj, S., Raja, P., Britto, S. John & Balaguru, B., 2018, A new species of Dalbergia (Fabaceae: Dalbergieae) from Tamil Nadu, India, Phytotaxa 360 (3), pp. 282-286 : 283-285

Dalbergia matthewii S. Soosairaj, P. Raja & S. John Britto , sp. nov. ( Fig. 1 ).

Type:— INDIA. Tamil Nadu, Western Ghats, Palani hills National Park, elevation 1450 m, 10° 21 ′ 48 ″ N, 77°44 ′ 16 ″ E, 6 Feb 2016, S. Soosairaj 2287 (holotype RHT, isotype MH).

Climbing liana, 5–8 m tall; branchlets rusty tomentose when young becoming glabrous, lenticels present, orbicular to elliptic. Stipules lanceolate, 7–8 × 3–5 mm, pubescent adaxially, glabrous abaxially, caducous. Leaves pinnate, 7.5–13.5 × 5.5–8.5 cm, petiolate; petioles 9–12 mm long; petiolules 2–4 mm long, rusty tomentose; leaflets 7 to 13, lateral leaflets elliptic, terminal leaflet obovate, 2.0–7.5 × 1.3–3.5 cm, base obtuse, apex retuse, lateral nerves 6 to 9 pairs, adaxial surface puberulous for half the lamina length along the midrib from the base, abaxial surface pubescent along the midrib and puberulous on lamina. Inflorescence axillary panicle, 2–4 cm long, rusty tomentose. Bract ovate, 2 mm long, rusty tomentose; bracteoles 2, ovate–elliptic, 2.2 mm long, rusty pubescent. Flowers 8–9 mm long, pedicel 1.5–2.0 mm long, tomentose. Calyx campanulate, 5× 3 mm long, rusty pubescent without, glabrous within, tube 4 mm long; 5-toothed, teeth subequal, upper 2 broader than lower, 1.3×2.0 mm, ovate–rounded, lower 3 longer than upper, 1.5–1.0 mm, lanceolate–ovate, acute. Corolla greenish yellow, petals clawed, glabrous; vexillum obovate, 5.0–5.5 × 3.5 mm, retuse at apex, claw 2.3 mm long; wings oblong, 5.5× 1.5 mm, base auricled, claw 2.2 mm long; keels boatshaped, jointed dorsally, 5.5– 1.8 mm, claw 2.5 mm long. Stamens 9, monadelphous, sheath 5–6 mm long, filaments 0.8–2.0 mm long, free in upper ¼; anthers dehiscent dorsally. Pistil 5 mm long; ovary stipitate, 4 mm long, strigose only on dorsal side, ovules 2; style bent, 1 mm long, glabrous; stigma minute. Pod oblong, stipitate, 3.0–6.8 × 1.0– 1.4 cm, thin and flat, brown, glabrous, reticulate throughout, base cuneate, apex obtusely apiculate, 1 (2)-seeded. Seeds reniform, 14–16 × 5–6 mm, brown.

Diagnostic characters: Dalbergia matthewii is a distinct species and is closely similar to D. gardneriana and D. congesta . It resembles D. gardneriana in having two bracteoles, a campanulate calyx, and monadelphous stamens, but differs by having a strigose ovary, brown reniform seeds and an obovate vexillum ( D. gardeniana has a villous ovary, black oval seeds and ovate vexillum). Dalbergia matthewii is similar to D. congesta in staminal sheath length (5–6 mm) and having 1 to 2 reniform seeds per pod. However, D. matthewii has a strigose ovary, obovate vexillum and rusty tomentose bract whereas D. congesta has a glabrous ovary, ovate–orbicular vexillum and puberulous bract ( Table 1).

Etymology: The new species is named in honor of Dr. K.M. Matthew, former Director of the Rapinat Herbarium, St. Joseph’s College (Autonomous), Tiruchirappalli, for his immense contributions to the taxonomic history of Peninsular India.

Phenology: Flowering occurs in February and March, and fruiting from April to May.

Distribution, ecology and conservation status: Dalbergia matthewii can be found growing along the borders of Southern Montane Wet Temperate Forest (11A/C1) (Champion & Seth 1968) and roads adjoining this forest in Palani Hills National Park (Western Ghats) of Tamil Nadu at an elevation range of 1300–1500 m. It is a liana with stems ranging from 100–240 mm in diameter. This species is associated with species such as Syzygium lanceolatum (Lam.) Wight & Arn. (1834: 230) , Symplocos cochinchinensis (Lour.) S. Moore (1914: 148–149) , Ardisia solanacea Roxb. (1795: 27) , Clausena dentata (Willd.) Roem. (1840: 40) , Celastrus paniculatus Willd. (1797: 1125) , Plectranthus mollis Spreng. (1825: 690) and Hibiscus lobatus (Murray) Kuntze (1898: 19) . The authors observed more than fifty mature individuals at this locality although the exact population size and its distribution range needs to be explored further.

Figures

FIGURE 1. Illustration of D. matthewii S. Soosairaj, P. Raja & S. John Britto. A. Flowering twig. B. A leaf with portion enlarged. C. Stipule. D. Bract. E. Flower. F. Bracteole. G. Calyx split open. H. Vexillum. I. Wing. J. Keel. K. Staminal sheath. L. Pistil. M. Pod. N. Seed (immature). A–K from living type material 2287, L and M from paratype material 2322. Drawn by P. Raja.