Larsenianthus assamensis S. Dey, Mood, & S. Choudhury, 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 : 22-23

Larsenianthus assamensis S. Dey, Mood, & S. Choudhury sp. nov. Fig. 3 Plate 1C

Latin

Species nova L. careyano affinis, a quo planta minore semidecumbenti, inflorescentia minore (circa 8 × 4 cm) ovoidea bracteis coccineis ad margines dentatis, ad bracteam quamque flore fertili solitari et labello angustiore magis roseo differt.

Type.

India: Assam: Cachar Dist., Bhaluknala, Barail Wildlife Sanctuary, narrow substream of Lakhicherra, 24°58'50.7" N, 92°46'30.8" E. Cachar tropical semi-evergreen forest, 26 m elevation, August 2007, S. Dey 1012 (holotype: CAL!; isotype: ASSAM!).

Description.

Evergreen herb, medium-sized to 144 cm tall, rhizome fibrous, elongate in distinct sections, bulbous, white-colored internally; tubers absent. Leafy shoots 7-17 per plant, erect or slightly decumbent, base bulbous. Leaves 7-12 per shoot, to 35 cm in total length; basal leaf sheaths 3-5, light pink, drying brown, deciduous; petiole 0-7 mm in length; ligule 7 mm in length × 5 mm in width, bilobed, apices rounded; lamina 24-34 cm in length × 5.4-8.5 cm in width, elliptic, dark green and glabrous above, base aequilateral, tip acuminate, midrib and veins depressed, abaxial surface dull green and glaucous. Inflorescence terminal on leafy shoot, erect to 14 cm in height; apical part of peduncle 3-5 cm in length × 3-5 mm in diameter, light green-brown, glabrous; involucral bract 4.2 cm in length × 1 cm in width, green, red striated, apex cirrose; 1 adventitious plantlet produced in sterile bracts at base of old inflorescence; spike ovoid to ellipsoid, 5.5-8.5 cm in length × 3.8-4 cm in diameter; inflorescence bracts c. 35 per inflorescence, 2.1-2.8 cm in length × 1-1.3 cm in width, ovate-oblong, concave, loosely clasping, red-veined, margin corrugate and denticulate, apex mucronate, revolute with long hairs, apical bracts smaller, sterile; one cincinnus per bract; bracteole lanceolate, cymbiform, 27 mm in length × 19 mm in width, semi-transparent, white, apex tapered, red. Flowers conspicuous, 1-4 per bract (usually only a single flower fertile); calyx tubular, 8-14 mm in length × 5 mm in diameter, trilobed, white, apex pink; floral tube 19-27 mm in length × 2-2.5 mm in diameter, pink-red, glabrous, corolla lobes linear-lanceolate, dorsal lobe 13 mm in length × 2 mm in width and reflexed 90°, ventral lobes 11 mm in length × 2 mm in width and deflexed and parallel to floral tube, orange-red with darker apex; lateral staminodes ovate, 6 mm in length × 3 mm in width, light orange with translucent dots, apex irregular, reflexed; labellum 22-25 mm in length × 2-3 mm in width, elongate, oblong, ‘v’ in cross-section, basal margins thickened, light orange, apex slightly trilobed, outer lobes 1 mm in length, rounded, curved upward toward apex, purplish-white; fertile stamen with filament c. 18 mm in length, arched, greenish purple at base, light orange-white distally, oblong, anther 3 mm in length × 0.5 mm in width, thecae glossy purple; pollen white; epigynous glands two, unequal, largest 3 mm in length × 0.5 mm in width and linear, smallest 2 mm in length × 0.5 mm in width and cylindric, dark purple; stigma 0.5 mm in length, extending 5 mm beyond anther, purplish; ovary trilocular, 2 mm in length × 1 mm in width, obovoid-oblong, unequally 3-lobed, pubescent, purplish. Fruits 8-9 mm in length × 4-4.5 mm in width, oblong to ellipsoid, white, capsular, dehiscing into three separate coiled sections, seeds 1-4, c. 3 mm in length × 2 mm in width, obovoid, seeds light to dark violet, enclosed in a cocoon-like arillate membrane.

Distribution.

Known only from two locations in the Barail Wildlife Sanctuary. Larsenianthus careyanus is also frequently found in this same region.

Ecology.

This species occurs in the understory of tropical semi-evergreen forest in very moist conditions along streams (rainfall 350-400 cm/yr) at 25-150 m in elevation. Associated plants are species of Musa , Curculigo , Begonia , Albizzia , Ampelocissus , Dysoxylum , Laportea , Uncaria , and ferns.

Etymology.

Named for the Indian state of Assam where this species is endemic.

Specimens examined.

India: Assam: Cachar Dist., Lakhicherra, Barail Wildlife Sanctuary, 24°59.053' N, 92°46.525' E. ca. 150 m. elevation, 30 August 2007, S. Dey s.n. (living material only).

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 3. Larsenianthus assamensis S. Dey, Mood, & S. Choudhury. A overall habit B leaf, entire C leaf base with petiole and ligule D inflorescence E inflorescence bract F bracteole G bract and flower, semi-lateral view H calyx, spread open I labellum with attached lateral staminodes J stamen showing base of floral tube and the epigynous nectaries K filament and anther with protruding stigma L epigynous nectaries and style. Line drawing by Linda Van Vorobik from plants in cultivation; voucher S. Dey 1012.