Larsenianthus arunachalensis M. Sabu, Sanoj & T.Rajesh Kumar, 2010

Kress, W. John, D. Mood, John, Sabu, Mamiyil, Prince, Linda M., Dey, Santanu & Sanoj, E., 2010, Larsenianthus, a new Asian genus of Gingers (Zingiberaceae) with four species, PhytoKeys 1, pp. 15-32 : 23-24

Larsenianthus arunachalensis M. Sabu, Sanoj & T.Rajesh Kumar sp. nov. Fig. 4 Plate 1D

Latin

Species nova L. careyano affinis, a quo inflorescentia centrali in caule bifoliato portata et ad bracteam quamque floribus fertilibus 2-3 differt.

Type.

India: Arunachal Pradesh: Lohit Dt.: Lalpani, Hayuliang Road, N 27°56'28.2", E 096°22'21.9", 6 August 2009, E.Sanoj & T.Rajesh Kumar 105640 (holotype: CAL!; isotypes: CALI!, ASSAM!).

Description.

Evergreen herb, medium-sized to 150 cm tall; rhizome 1.9 cm in diameter, hard, fibrous, slightly aromatic, inner color pale brown; tubers absent. Leafy shoot erect; base 2.5-3 cm in diameter. Leaves two per flowering shoot, to 120 cm in total length; basal leaf sheaths 4-6, red and green, densely pubescent towards apex; petiole 19.5-31 cm in length, cross section U-shaped, pubescent, green; ligule 9.5-14 cm in length × 2.4-2.7 cm in width, lanceolate, apex attenuate, pubescent abaxially, becoming dry and brown; lamina 56-88 cm in length × 19-25 cm in width, abaxially pale green and densely pubescent with silvery hairs, elliptic, dark green, and glabrous above, veins raised 4-6 mm, margins entire, undulate, hyaline, white tinged, base attenuate, apex long acute, slightly twisted. Inflorescence terminal on leafy shoot, erect to 90 cm in height; apical part of peduncle 25-75 cm in length, c. 1.2 cm in diameter, pubescent, pale green; spike elliptic, 14-19 cm in height × 3-3.4 cm in diameter; inflorescence bracts 60-80 per inflorescence, bracts 2.4-2.9 cm in length × 2.6-2.8 cm in width, spirally arranged and tightly imbricate, orbicular to broadly elliptic, cymbiform, free to the base, coriaceous, deep red, base white tinged, margin entire and smooth, glabrous, apex acute to rounded, surfaces pubescent, dense brown hairs toward apex; one cincinnus per bract; bracteoles tubular, longer than bracts, 2.8-3.3 cm in length, unilaterally split 1 cm, apex acute to rounded, deep red, white tinged towards base, densely pubescent with short brown hairs towards apex. Flowers conspicuous, 2-4 per bract, 2-8 flowers open simultaneously on inflorescence; calyx tubular, 16-17 mm in length × c. 3 mm in width, apex trilobed, unilaterally split 5-6 mm, pale red, white towards base, pubescent with denser hairs towards apex, membranous, translucent; floral tube 3.2-3.3 cm in length × c. 3.5 mm in diameter at opening, red, lobed with each lobe 15-17 mm in length, oblanceolate, dorsal lobe reflex, sparsely pubescent externally with scattered unicellular branched hairs inside, lateral lobes glabrous; lateral staminodes c. 4 mm in length × 3.5 mm in width, orbicular to broadly elliptic, white with pale red tinge, revolute; labellum 25-28 mm in length × 2.5-3 mm in width, narrowly oblong in first two-thirds and oblanceolate distal third, semi-spathulate, red to creamy yellow towards base and orange-yellow towards acute, beak-like apex; fertile stamen with filament 2.4-2.6 cm in length, red becoming creamy-yellow near anther, arching like a fish-hook; anther c.3 mm in length × 2 mm in width, creamy yellow, glabrous; epigynous glands two, oblong, white, 2.5-3.0 mm in length; stigma c. 0.5 mm wide, white, bulbous, margins ciliate, exserted 2-2.5 mm from the middle of the anther; ovary trilocular, c. 3 mm in length × 2.5 mm in diamter, tomentose, pale red. Fruits and seeds unknown.

Distribution.

Larsenianthus arunachalensis is narrowly endemic in Arunachal Pradesh, India, and is known only from the type locality. It is highly endangered due to various anthropogenic activities.

Ecology.

This species grows in sandy soil above 1,400 m in elevation amidst thick clumps of wild species of Musa .

Etymology.

The specific epithet “arunachalaensis” is derived from the name of the state in northeast India from where the type specimen was collected.

Specimens examined.

Known only from the type specimen.

Figures

Plate 1. Inflorescences with flowers of A Larsenianthus wardianus W. J. Kress, Thet Htun & Bordelon B Larsenianthus careyanus (Benth.) W. J. Kress & Mood C Larsenianthus assamensis S. Dey, Mood, & S. Choudhury D Larsenianthus arunachalensis M. Sabu, Sanoj & T. Rajesh Kumar. All photos by the authors.

Figure 4. Larsenianthus arunachalensis M. Sabu, Sanoj & T. Rajesh Kumar. A inflorescence B apical part of leaf sheath with ligule and petiole C inflorescence bract D bracteole E calyx F flower, lateral view G floral tube H labellum I lateral staminodes J anther, front, back and lateral views K unicellular branched hairs inside corolla tube L stigma and upper portion of style M base of flower, cut-way view to show style and epigynous nectaries N ovary, transverse section. Line drawing by E. Sanoj from plants in cultivation; voucher Sanoj & Rajesh Kumar 105640.