Talinella ankaranensis Appleq., 2005

Applequist, Wendy L., 2005, A revision of the Malagasy endemic Talinella (Portulacaceae), Adansonia (3) 27 (1), pp. 47-80 : 54-56

2. Talinella ankaranensis Appleq. , sp. nov.

Haec species Talinellae boivinianae Baill. affinis, sed ab ea inflorescentiis lateralibus distantibus anguste ovoideis foliis paucioribus subtentis, bracteis plerumque minus quam 0.7 mm longis apice fuscato, sepalis 1.5- 2.3 mm longis non incrassatis atque florum masculinorum petalis 4-5 mm longis filamentis interioribus 4-5 mm longis ac stylis usque ad 1.5 mm longis differt.

TYPUS. — Humbert 18940, Madagascar, Prov. Antsiranana, Ankarana, forêt tropophile près d’Ambondrofe , 300 m, 12°53’S, 049°12’E, fl., Dec. 1937 - Jan. 1938 (holo-, P!; iso-, P!, MO!) .

Liana or lianoid shrub. Twigs straight, with few or no lenticels, glabrous, brown to grayish brown or yellowish or mottled black on old branches, occasionally with a peeling waxy outer layer. Leaves broadly elliptical rarely to lanceolate, 2.25-4.5(-6) cm long, (0.75-)1.5-2.5(-3.5) cm broad, often slightly asymmetrical, glabrous; apex rounded to short-apiculate or acute; base tapering at attachment to petiole, often slightly concave, otherwise rounded; margins entire to slightly undulate; blade thin to succulent; petiole and midrib reddish; midrib conspicuous beneath, secondary venation invisible or inconspicuous. Inflorescences lateral or rarely terminal, widely spaced, narrowly ovoid, 10-30 cm long with numerous flowers; peduncle and rachis sturdy, glabrous; bracts 0.3-0.7(-1.1) mm long, narrowly triangular to triangular, apex dark-tipped, possibly purplish in vivo. Dioecious. Pedicel 3- 4(-5) mm long. Sepals 1.5-2.3 mm long, orbicular, sometimes asymmetrical, not strongly thickened; apex rounded. Petals 3-5, where less than 5 visibly derived from incomplete connation of 5 petals, 4-5 mm long in male flowers, 2.2- 3.6 mm in female flowers, with distinct sexual dimorphism, greenish-yellow to nearly white; unfused petals oblong to obovate, frequently convex. Stamens numerous, attached to ring-shaped nectary disk; filaments of outer ring filiform, c. 2.5 mm long; filaments of inner ring 4.5-5 mm long, the lower two-thirds thickly ciliate, the upper portion filiform; anthers yellow, 0.35- 0.4 mm long; pollen yellow. Female flowers with well developed staminodes, resembling inner ring of male filaments, except largely antherless; stigma branches 2, 1- 1.1 mm long, sometimes on short style, nearly sessile at maturity; ovary reddish. Immature fruit bacciform, globose. — Fig. 3 .

Talinella ankaranensis is distinguished from T. boiviniana , from which it is herein segregated and to which it is certainly a sister species, by more pronounced sexual dimorphism and larger male floral parts (petals 4-5 mm long vs 3-4 mm, inner stamens to 5 mm long vs 4 mm), with the exception of the sepals, which are slightly smaller and are not conspicuously thickened. Talinella ankaranensis may have a somewhat greater tendency to petal fusion; the inflorescence bracts are fewer, smaller (usually <1 mm long vs 0.7- 2.0 mm in T. boiviniana ) and more frequently dark-tipped. The inflorescences of T. ankaranensis are often long, narrow lateral panicles borne on one side of a rather lianoid stem, whereas

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T. boiviniana frequently has terminal inflorescences, and its lateral panicles are often small and clustered or irregularly spaced on leafy shoots, usually not confined to one side of the stem. Talinella ankaranensis is said to be a liana on some labels, although this must be interpreted with caution as other highly sarmentose species have been inaccurately described by collectors. Its habitat is on limestone, especially tsingy; T. boiviniana has been reported on calcareous substrate at Orangéa, but probably occurs most often on quartz sand. BARDOT- VAUCOULON (1997) mentioned the presence of two unnamed species of Talinella at Ankarana, presumably referring to this species and to T. pachypoda , both of which she collected in the area.

DISTRIBUTION. — Talinella ankaranensis is known only from northern Madagascar in the vicinity of Ankarana ( Fig. 4 ), on calcareous substrates, at 10-300 m elevation.

VERNACULAR NAME. — Vahiloko ( Humbert 18878).

CONSERVATION STATUS. — Provisional IUCN Red List Category: Vulnerable (VU D2). Talinella ankaranensis is known only from a single location, the reserve of Ankarana. Though label data of existing specimens are inadequate to determine distribution precisely, area of occupancy is likely to be small.

PARATYPES. — MADAGASCAR: Prov. Antsiranana: Bardot-Vaucoulon 202, tsingy du plateau, massif de l’Ankarana, fl., fr., 2 and 17 Nov. 1990 ( P, MO); Bardot-Vaucoulon & Andrianantoanina 986, Ambilobe, Ankarabe , Réserve Spéciale d’Ankarana , Andavenoko , tsingy et éboulis, forêt sèche caducifoliée, sommet de tsingy, végétation en mosaïque, arbres rabougris et plantes xérophytes, sol squelettique dans les creux et les fissures sur calcaire du Jurassique moyen, 12°58’29”S, 049°04’04”E, 100 m, fl., 27 Nov. 1997 ( MO); Humbert 18878, collines et plateaux calcaires de l’Ankarana, base de la falaise NW, 10-50 m, fl., Dec. 1937 - Jan. 1938 ( P, MO); Morat 3088, falaise calcaire de l’Ankarana, Jan. 1969 ( TAN) .

Incertae sedis: Andrianantoanina & Bezara 999, Fivondrana Antsiranana II, environ de Parc National de Montagne d’Ambre, à 91 km SW d’Antsiranana par rte secondaire vers Bobakilandy, 2 km NW du village de Bobakilandy, forêt sèche et humide, 12°37’43”S, 049°04’27”E, 507 m, fl., 29 Oct. 1996. This specimen is lianoid with a hollow stem and rather narrow leaves; most inflorescences are narrow and lateral on long flexuous shoots, and the bracts are dark-tipped and mostly <1.2 mm long. However, its flowers rather resemble those of T. boiviniana , with small but thick and bullate sepals, petals 3. 0-3.5 mm long, and filaments actually shorter than the normal range. The locality is closer to the known range of T. ankaranensis , but the substrate cannot be limestone (perhaps granite). On the other hand, T. boiviniana is found mostly on sand near sea level, never at high altitude. This collection may represent simply an atypical population of T. ankaranensis , or it might be a distinct subspecies or even species. Its apparent intermediacy is probably not due to recent hybridization, given the distance between the ranges of T. ankaranensis and T. boiviniana ; it might reflect this locality’s position in a perhaps historically broader distribution of the common ancestor of those two taxa. Lacking further material, formal description would be inappropriate.

Figures

FIG. 3. — Talinella ankaranensis Appleq.: A, habit; B, male flower; C, female flower; D, leaf (adaxial surface); E, leaf (abaxial surface); F, detail of inflorescence. A-E, Humbert 18940; F, Bardot-Vaucoulon 202.

FIG. 4. — Distributions of Talinella species from the extreme north: T. ankaranensis (●), T. boiviniana (▲), T. pachypoda ($).