Psychotria speciosa G. Forst.

Lorence, David H., Florence, Jacques & Meyer, Jean-Yves, 2017, Reassessment of the Psychotria speciosa G. Forst. (Rubiaceae) complex in Tahiti, Society Islands, with a new combination and description of new species, Psychotria paulae J. - Y. Meyer, Lorence & J. Florence, sp. nov., Adansonia 39 (1), pp. 41-53 : 46

Psychotria speciosa G. Forst.

( Fig. 2 )

Florulae Insularum Australium Prodromus: 16, taxon 89 (1786). — Cephaelis speciosa (G. Forst.) , Spreng., Systema vegetabilium 1: 749 (1824). — Uragoga speciosa (G. Forst.) Drake, Illustrationes Florae Insularum Maris Pacifici 15: 38 (1890). — Lectotype, here designated: Society Islands,Tahiti, without locality or date (fl. buds), G. Forster 57 (GOET[GOET012552]!). The sheet is annotated “57. Psychotria speciosa Prodr. 89” perhaps in handwriting of G. Forster; on a second blue label is written “Original Forster” with a det. slip by F. R. Fosberg “57. Psychotria speciosa Forst. f. in 1986”. Due to the poor condition of the lectotype, we also designate the following specimen as epitype.

EPITYPE. — Here designated: Society Islands. Tahiti, plateau deTaravao, captage de l’Hamoa, 17°47’S, 149°15’W, 950 m, 9.II.1983, (fl.), J. Florence 4492 (epi-, P[P02286909]!; isoepi-, BISH, P[P02286910]!, PAP).

DISTRIBUTION, HABITAT AND ECOLOGY. — Psychotria speciosa occurs as isolated plants in mid-elevation forests at 700-1500 m. Its ecology is poorly known, but collectors’ notes indicate it is rare in high valleys along streams associated with species of Cyathea Sm. and Cyrtandra J. R. Forst. & G. Forst. Many of these areas are invaded by Miconia calvescens DC.

REPRESENTATIVE SPECIMENS. — Society Islands . Tahiti, Plateau de Taravao, captage de l’Hamoa, 930 m, 17°47’S, 149°15’W, 9.II.1983, J. Florence 4487 ( P [ P02286904 ]!) . Without precise locality: bel arbrisseau dans les hautes vallées, fl. & fr., s.d., Vieillard s.n. ( P [ P00701046 ]!) ; b. fl., Vieillard s.n., s.d. ( P [ P02286905 ]!) .

DESCRIPTION

Shrubs or treelets 2-4 m tall, sparsely branched, vegetative parts glabrous; twiglets cylindrical, fistulose. Leaves of a pair equal or subequal; stipules caducous, united into a calyptra 2-2.5 cm long, terminated by a narrowly elliptic appendage 0.4-0.8 cm long, ± bifid at the tip; petiole stout, 1.2-5.2 cm long; blade when fresh light green to bright green above, paler below, subcoriaceous, obovate, elliptic or oblong-elliptic, 5.3-19.2 cm long, 6.2-9.3cm wide, base cuneate to very narrowly decurrent, apex obtuse or rounded to acute or short acuminate, abaxially with whitish or reddish brown domatia sometimes present in secondary vein axils, costa flattened adaxially, prominulous abaxially, secondary veins 8-13 on each side, prominulous abaxially, tertiary vein network inconspicuous. Inflorescence terminal, in bud enclosed in a stipule-like calyptra 3.3-4.5 cm long, bifid at apex, enclosing 3-9 densely clustered sessile or subsessile flowers, inflorescence becoming pseudo-axillary by development of sympodial vegetative branch. Flowers fragrant when fresh, monomorphic. Hypanthium glabrous, turbinate, 2.5-4.2 mm long, 2-3.3 mm wide, calyx pale green, tube 2.5-4.2 mm long, 2.8-4 mm wide, flared; calyx lobes linear to triangular-ovate, narrowly oblong, or spathulate, 2.8-5.2 mm long, 1-1.8 mm wide ( Fig. 2 A-D). Corollas white, fleshy, hypocrateriform, tube 2.8-3.5 cm long, 2.0- 2.5 mm in diam., straight or slightly curved, glabrous without or the lobes sparsely puberulent, lobes narrowly oblong-triangular, 1.3-1.5 cm long, 2.1-2.5 mm wide, recurved at maturity, papillose to tomentellose within, more densely so at the throat, apex acute, uncinulate at tip.Stamens inserted below top of tube; anthers sessile, linear, 2.8-3 mm long. Style 2.8-3.3 cm long, reaching throat, pubescent in distal third, stigmatic branches c. 2 mm long, scarcely exserted or exserted for 2-3 mm, spreading at maturity, ventrally with white hairs 0.3 mm long, apex disciform-lobed; nectary disc glabrous. Infructescence terminal or lateral by displacement. Fruits sessile or scarcely pedicellate, clustered, ellipsoid-ovoid to subglobose, 1.5-2.2 cm long, 0.8-1.1 cm wide, red at maturity, apex umbonate.Pyrenes ellipsoid, 1.4-1.7 cm long, 0.7-1.0 cm wide, 0.2-0.4 cm thick, ventral surface plane, dorsal surface with two marginal and one central crests; preformed germination slit ventral, extending ¼-1/3 distance from apex ( Fig. 5B ). Endosperm not ruminate, lacking reddish alcohol-soluble pigment.

IDENTITY OF PSYCHOTRIA TRICHOCALYX , COMB. NOV.

Drake Del Castillo(1886) considered Nadeaud’s “Var.D cymosa ” of P.speciosa to represent a distinctive species with inflorescences having villous peduncles and calyces and described it as Uragoga trichocalyx Drake , citing two specimens (Lépine 184 and Nadeaud 343). He later (Drake Del Castillo 1892) transferred it to Calycosia A. Gray as Calycosia trichocalyx (Drake) Drake. Calycosia is a genus of six to eight species distributed in Fiji, Samoa, the Solomon Islands, and New Guinea. It is closely related to Psychotria ( Smith & Darwin 1988; Andersson 2002) and is distinguished morphologically by the capitular or capitular-cymose inflorescences with conspicuous, often numerous, pale green to white, free or united, involucrate stipule-like deciduous bracts, and flowers with a large, infundibular calyx limb, deciduous in fruit ( Smith & Darwin 1988). However, Smith & Darwin (1988) stated these characters are not reliable in separating the genus from all groups of Psychotria . Our observations reveal that young inflorescences of many Pacific Psychotria species are enveloped by stipules or stipule-like bracts. Capitular-cymose inflorescences occur in several Marquesan and Micronesian Psychotria species ( Fosberg & Sachet 1991; Lorence &Wagner2005; Lorence &Wood 2012). Furthermore, calyx limb size and lobing varies considerably between Psychotria species. For these reasons we believe C. trichocalyx is best placed in Psychotria and make the following new combination.

Figures

FIG. 2. — Psychotria speciosa G. Forst., various calyx forms: A, C, D, form with campanulate calyx and triangular-ovate to spathulate lobes; B, basal part of dissected flower bud from lectotype specimen showing triangular-ovate calyx lobe (arrow); orientation is horizontal, base of bud is to left. A, C, D, Tahiti, Marau, J.-Y. Meyer photos; B, Forster 57 (lectotype, GOET), E. Carnero-Diaz photo.

FIG. 5. — Pyrenes of two Tahitian Psychotria L. species,adaxial (left) views showing preformed germination slits, and abaxial (right) views:A, P. paulae J.-Y. Meyer, Lorence & J. Florence, sp. nov., Meyer 2468; B, P. speciosa G. Forst., Quayle 270 (BISH).