Humboldtia ponmudiana E.S.S.Kumar, Shareef et Raj Vikr., 2022

Kumar, Ettickal Sukumaran Santhosh, Shareef, Sainudeen Muhammed & Vikraman, Ramachandrakurup Raj, 2022, Humboldtia ponmudiana (Fabaceae-Detarioideae), a new species from Kerala, India, Phytotaxa 552 (1), pp. 115-121 : 116-119

Humboldtia ponmudiana E.S.S.Kumar, Shareef et Raj Vikr. sp.nov. ( Figures 1 , 2 & 3B )

Type:— INDIA, Kerala, Thiruvananthapuram District, Ponmudi , 800 m., 09.12.2021, E.S. Santhosh Kumar & S.M. Shareef 96319 (holotype TBGT !, isotype TBGT!, MH!, CAL!).

Diagnosis:— Humboldtia ponmudiana is closely similar to H. decurrens , but differs in having black coloured bark, densely brown tomentose young shoots, lanceolate or ovate-lanceolate leaflets with densely brown tomentose midribs, sessile or subsessile flowers, fairly large broadly ovate eglandular bracts, connate to middle bracteoles with adaxial glabrous surfaces, fairly large anthers, 1–4 ovuled ovaries and silky tomentose pods with long beak ( Table 1 ).

Descripton:—Moderate sized trees, 5–12 m tall; trunk 25–50 cm in diameter, bark black, warty; blaze light crimson; young shoots densely brown tomentose, glabrescent at maturity. Stipules 5.5–6.0 × 1.5–2.0 cm, ovatelanceolate, slightly falcate, acuminate to cuspidate at apex, prominently parallel veined, depressed glandular, densely brown tomentose when young and glabrescent at maturity; appendages 1.0–1.7 × 1.6–2.3 cm, reniform, obtuse or rarely acuminate on one side, densely tomentose when young, glabrescent at maturity. Leaves up to 45 cm long, subsessile, 8–12- foliolate; young leaves pendulous, creamy-white suffused with light pink, densely brown tomentose; rachis obcordately or decurrently winged, wings reticulately veined, densely brown tomentose on both surfaces; petiolules 2–4 mm long, not covered by rachis wings, densely brown tomentose, depressed glandular; leaflets 10.5–37 × 3.0–7.0 cm, lanceolate or ovate-lanceolate, subcordate or rounded at base, acuminate to caudate-acuminate at apex, slightly undulate at margins, subcoriaceous, depressed glandular, densely brown tomentose beneath; lateral nerves 10–19 pairs, shallowly depressed above, prominently raised beneath and arching 2.0–3.0 mm away from the margin forming a prominent intramarginal vein. Racemes 5.0–9.0 cm long, pendulous, axillary or cauliflorous, subsessile; rachis terete, brown tomentose, many flowered. Flowers c. 3.5 cm across at anthesis, white, sessile or subsessile; pedicels absent or rarely up to 0.2 cm long, brown villous; bracts 1.0–1.2 × 0.7 cm, broadly ovate, greenish-white, acuminate at apex, brown villous and eglandular without, glabrous within, fugacious; bracteoles 2, 1.0–1.3 × 0.7 cm, ovate, obtuse at apex, greenish-white, connate to middle in cauliflorus flowers or connate to middle on one side and free up to the base on the other side in axillary flowers, silky villous and glandular without, glabrous within. Calyx tube 0.8–1 cm long, obconic, silky villous; lobes 4, 1.2–1.8 × 0.4–0.7 cm, subequal, one larger than the rest, elliptic-oblong or linearoblong, creamy-white, rounded at apex, silky villous on both surfaces. Petals 5, 1.6–2.3 × 0.6–1.0 cm, obovate to oblanceolate, white, clawed at base, acute or slightly acuminate at apex, glabrous or minutely silky pilose along the midrib abaxially. Stamens 5, 3.5–4.0 cm long; filaments filiform, pink, broad and silky pilose at base; anthers 3.5–4.0 mm long, pink, obtuse at both ends. Ovary 0.8–1.0 cm long, stipe 1.0– 1.5mm long, obliquely linear, silky villous, 1–4 ovuled; style filiform, 2.7–3.0 cm long, rarely coiled, glabrous, pink; stigma capitate. Pods 13–15 × 3–4 cm, oblong, silky tomentose; beak 2–2.5 cm long. Seeds 2–3, thick, flat, glabrous.

Flowering & Fruiting: —December - February

Habitat, Ecology and Conservation status: —This species is found in the evergreen forests of Ponmudi hills between 700–800 m elevations in Agasthyamala Biosphere Reserve (ABR), Kerala. The main associated species are Antidesma montanum Blume (1827:1124) , Arenga wightii Griffith (1845:475) , Croton malabaricus Beddome (1873: 204) , Dimocarpus longan Loureiro (1790: 233), Diospyros paniculata Dalzell (1852:109) , Elaeocarpus tuberculatus Roxburgh (1832:594) , Pandanus thwaitesii Martelli (1905:369) , Pinanga dicksonii (Roxb.) Blume (1839:77) , Quisqualis malabarica Beddome (1874:33) , Syzygium munronii (Wight) N.P. Balakrishnan (1982:174) , Thottea ponmudiana Sivarajan (1985:202) , Vateria indica Linnaeaus (1753:515) , etc. The present population consists of less than 50 mature trees and several seedlings of various ages occupying an area of less than 5 km 2. Following the IUCN Red List criteria ( IUCN 2020), H. ponmudiana is assessed as Critically Endangered (CR) in the category [B2a, b (v)].

Distribution:—Endemic to Kerala

Etymology:—The new species is named after the type locality, Ponmudi, an important hills station in south Kerala.

Additional Specimens examined:— INDIA, Kerala, Thiruvananthapuram District, Ponmudi, 760 m., 22.12.2021, E.S. Santhosh Kumar & S.M. Shareef 96335; ibid, 10.02.2022, E.S. Santhosh Kumar & S.M. Shareef 96336 (Paratype TBGT!).

Figures

FIGURE 1. Humboldtia ponmudiana:A. Habit, B. Basal portion of the main trunk, C. Bark, D. Blaze, E.A mature plant, F.Close up view of branches, G.Young leaves, H. Mature leaf-adaxial view, H1. Mature leaf-abaxial view, I. An young stipule, J. Mature stipule-outer view, K. Mature stipule-inner view, L. Petiolules, M. Part of an inflorescence shows sessile flower buds, N. An axillary raceme shows sessile flowers. (Photographs by E.S.Santhosh Kumar).

FIGURE 2. Humboldtia ponmudiana:A. A bract, B. A connate bracteole in cauliflorus flower, C. A bracteole in axillary flower, D. A flower (4 petals and one stamen removed), E.Calyx, F. A petal, G. A stamen, H. An anther, I. Pistil with coiled stigma, J. A typical flower showing calyx, staminoide and pistil (petals and stamens removed). (Photographs by E.S.Santhosh Kumar).

FIGURE 3. A. Pod of Humboldtia decurrens, B. Pod of Humboldtia ponmudiana (Photographs by E.S.Santhosh Kumar).