Thismia, Griffith, 1845

Nuraliev, Maxim S., Yudina, Sophia V., Truong, Ba Vuong, Do, Thi Xuyen, Luu, Hong Truong, Kuznetsov, Andrey N. & Kuznetsova, Svetlana P., 2020, A revision of the family Thismiaceae (Dioscoreales) in Cambodia, Laos and Vietnam, Phytotaxa 441 (3), pp. 229-250 : 242-243

Thismia . puberula Nuraliev in Nuraliev et al. (2015: 135, Fig. 1–3 ) ( Fig. 5 )

Literature:— Kumar et al. (2017: 232), Nuraliev et al. (2019: 150, Fig. 1K )

TYPE: — VIETNAM. Dak Lak Province: Lak District, Bong Krang Municipality, Chu Yang Sin National Park, 12 km S of Krong Kmar village, in the forest, on an islet of a small river, elevation ca. 1100 m a.s.l., N 12°23’41’’ E 108°20’55’’, 28 May 2014, M. S. Nuraliev 1000 (holotype: MW: MW 0595664!, stored in ethanol).

Description

Plant generally glabrous, branching by the formation of root suckers. Roots vermiform. Leaves ca. 8, scattered, up to 6–7 mm long. Pedicel (internode between involucral bracts and ovary) ca. 1–3 mm long. Flower terminal and solitary (but with a small lateral bud which probably develops into a lateral flower), actinomorphic, 19–22 mm long from ovary base, surrounded by an involucre of 3 bracts up to 7.5 mm long. Hypanthium obconic, 7–8 mm long (excluding inferior ovary), ca. 5.8–7 mm wide in the upper part; involucral bracts reaching one third of hypanthium or less; outer hypanthium surface with 18 raised longitudinal veins, smooth, dark grayish-brown and gradually becoming darker distally with narrow white collar in upper part, veins slightly darker than surrounding tissue; inner surface without transverse bars, slightly rugose, fenestrated, uniformly brown with white collar with netlike orange thickenings in upper part (above the level of stamen appendages). Annulus ca. 1.5–2 times broader than tall, dome-shaped with delimited vertical part (wall, 2.5–4.3 mm high, slightly rounded outside) and horizontal part (roof, 4.5–5 mm wide) with abrupt right angle between them, fleshy, uniformly covered outside by dense very short hairs; annulus orifice roundish triangular with 3 incisions in the radii of inner tepals, ca. 1.5 mm in diam.; annulus wall white, roof reddish-orange with gradual transition between them. Outer tepals spreading, broadly triangular, 1–1.5 mm long, 3–3.5 mm wide at base, white, slightly translucent, margin entire, apex acute to acuminate. Inner tepals distally arching inward and apically broadly fused (inseparable without tearing) to form a fleshy mitre with prominent furrow-like sutures and leaving 3 broad trapezium-shaped lateral apertures 4–5 mm wide between mitre, two neighbouring free basal tepal parts and annulus. Free parts of inner tepals erect, thick, broadly attached to annulus wall along its entire height by ventral keel, basally ca. 2.5–3 mm wide, narrowed slightly above to ca. 1 mm wide, broadened towards mitre and sharply delimited from it; free parts each with marginal thickenings and dorsally raised median vein. Mitre almost round (in top view), with straight horizontal lower edges (in side view) occupying level of annulus apex (making gap scarcely visible from side), 3.5–5 mm high and 8–9.7 mm wide; inner surface slightly concave and uniformly covered by dense papillate trichomes; outer surface convex with 3 foveae at top alternating with inner tepals and together forming a vallate depression ca. 4 mm wide, with median veins slightly prominent below foveae and raised to form crest-shaped borders between foveae; crests connate at mitre centre to form a minute tip; outer surface with 2 impressed lateral veins in each tepal at angle of 45º to median vein. Inner tepals white with thinner parts translucent except reddish brown central mitre tip. Stamens ca. 4–5.5 mm long, with long supraconnectives, fused laterally along their entire length except for the filaments and the rounded apices to form a stamen tube. Bases of filaments occupy entire height of annulus. Each stamen with deep median longitudinal furrow at the inner (abaxial) side. Supraconnectives bearing skirt-like appendages at the outer (adaxial) side slightly below thecae, concave adaxially below the appendages; each appendage as wide (ca. 1.5 mm) as supraconnective, inclined towards the supraconnective apex and not reaching it, with convex quadratic main lamina and perpendicular marginal wing-like projections of lamina forming H-shaped structure (in bottom view) which are attached to supraconnective tissue so that proximal parts of projections shortly triangularly attenuate towards outside (and decurrent proximally towards the thecae) and distal parts narrowly rounded. Thecae adaxial (facing the hypanthium), separate, ca. 1–1.3 mm long. Androecial indumentum of up to 10 papillae at the apex of each supraconnective, long needle-like hairs at the margins of appendages, and 2 rows of shorter glandular hairs on the sides of each theca. Interstaminal glands present. Stamens light orange adaxially (outside) including appendages, pale rose abaxially (inside). Ovary outside not delimited from hypanthium except being white, obconic, 2–2.5 mm long, 3–3.6 mm wide towards apex. Placentas column-like. Stylar column shortly cylindrical, ca. 0.7–1 mm long, ca. 0.6 mm in diam., dark blue; styles ca. 2.7–3.6 mm below stamen apices, upright, appressed to each other, simple, rectangular, 0.6–1.2 mm long, bearing densely finely papillose stigmas, translucent light blue with brownish apices.

Etymology: —The specific epithet “ puberula ” refers to the puberulous annulus characteristic of this species.

Phenology: —Flowering from late May to June.

Additional specimens examined: — VIETNAM. Dak Lak Province: Lak District, Bong Krang Municipality, Chu Yang Sin National Park, 12 km S of Krong Kmar village, in the forest, near small river, 1100 m a.s.l., N 12°23’41’’ E 108°20’55’’, 27 May 2019, S.V. Yudina, M.S. Nuraliev 15 (MW).

Distribution: —Endemic to Vietnam, Chu Yang Sin National Park. Known from a single location where it was collected twice.

Notes:— Thismia puberula is morphologically very close to T. okhaensis . This proximity is consistent with their geographical distribution, as these species are found in similar habitats in two neighbouring mountain systems with a distance of about 80 km between their populations. Moreover, Thismia puberula and T. okhaensis appeared to be sister species in a molecular phylogenetic reconstruction by Shepeleva et al. (2020). Thus, their taxonomic individuality is to be verified. One of the main morphological features distinguishing these species is the structure of the outer surface of mitre ( Nuraliev et al. 2015). In T. puberula , it bears evident foveae, whereas in T. okhaensis it is digitately furrowed. However, the photograph included in the protologue of T. okhaensis ( Luu et al. 2014, Fig. 2E ) shows a mitre of a very asymmetric appearance in its central part, suggesting that it was developed after a damage or represents a kind of teratologic morphology. For this reason, taxonomic significance of the outer surface of mitre for delimitation of these two species is currently questionable. On the other hand, several characters of the annulus are still essentially different in these species. In T. puberula , the annulus is dome-shaped with delimited vertical and horizontal parts, with narrow orifice, hairy outside and with stamen filaments attached along the entire annulus height; in T. okhaensis , in contrast, annulus is vertical, with a broad aperture, glabrous and with stamen filaments attached at the basal annulus half. Additionally, in T. puberula the annulus is reddish-orange distally, whereas in T. okhaensis it is entirely white. Finally, the flowers of T. okhaensis are considerably larger than those of T. puberula (30 vs. 19–22 mm long), although the measurements were performed on a limited material: to date, three flowers were examined for T. okhaensis and four of them for T. puberula . Summarizing, we consider T. puberula and T. okhaensis as separate species at the current state of knowledge.

Figures

FIGURE 1. Distribution map of the species of Thismia in Cambodia, Laos and Vietnam.

FIGURE 2. Thismia annamensis. A–D. Nuraliev 1562; E–G. Nuraliev 999. H. Nguyen Quoc Dat et al. Pl_Q.NG 0025; all photos by M. Nuraliev except for H by Nguyen Quoc Dat. A. Habit. B, E. Flower, apical view. C. Annulus and stamens, lateral view. D. Flower, longitudinal section. F. Flower with a longitudinal half of hypanthium removed, oblique-bottom view. G. Longitudinal section of distal part of flower showing stamen structure. H. Styles, apical view.

FIGURE 3. Thismia javanica. A–D. Do Thi Xuyen et al. BHH 800, photos by Do Thi Xuyen and SEM image by S. Yudina; E–I. Truong Ba Vuong et al. BV426, photos by Truong Ba Vuong. A, E. Flower, apical view. B, F. Flower, lateral view. C. Longitudinally opened and flattened hypanthium showing stamens. D. Supraconnective, abaxial view (SEM). G. Flower, oblique view. H. Flower with longitudinally opened hypanthium (three stamens removed). I, Three stamens, adaxial view.

FIGURE 5..Thismia puberula. A–C. Lateral views of flowers showing variation of flower shape. D, E. Mitre, oblique and apical views. F. Perianth, showing inner surface of mitre. All photos by M. Nuraliev from Yudina et al. 15.