Decaisnina djamuensis (Krause) Barlow, comb. nov.

Distribution Map

map


Description (Barlow 1993)


Loranthus djamuensis Krause, Bot Jahrb. 57 (1922) 478. -Decaisnina djamuensis (Krause) Barlow, Austral. J. Bot 22 (1974) 536. - Type: Schlechter 17319 (holo B; iso S), New Guinea, Djamu (Ramu) R, 600 m, 21.ii.1908.

For description and synonymy see Barlow, Austral. J. Bot. 22 (1974) 536. Decaisnina djamuensis has few specialized characters, and thus presents a relatively generalized facies for the genus. The species can be identified locally by its combination of scurfy brown internodes, distinctly petiolate, isofacial, powdery green leaves with the distinct brown midrib raised in the lower part, triads with lateral flowers shortly pedicellate and conspicuous rounded bracts, conspicuous calyx 1 mm long, and usually pale-coloured petals more than 15 mm long and separating to the base at anthesis. The flower colour has mostly been recorded as green, sometimes shading to yellow or red in the upper part, rarely red.

Decaisnina djamuensis is distributed in New Guinea (Fig. 6; 13 collections seen), recorded mostly in lowlands at elevations from sea level to 200 m but occasionally up to 1050 m. As a result of this study the known area of the species has been reduced to mainland New Guinea and Biak, the specimens from New Britain being transferred to D. longipes. Habitat details are poorly known; recorded hosts include Anisoptera, Cinnamomum, and Eucalyptopsis.

The species is distinctive in vegetative, inflorescence, and flower characters. It is probably related to D. micranthes, which occurs sympatrically in the Vogelkop area of western New Guinea, and which differs in having much smaller flowers more distantly spaced in the inflorescence. Wider relationships are not readily apparent. Diversity in Decaisnina is relatively high in western New Guinea, possibly reflecting differentiation and adaptation in immigrant stocks which have crossed Charles's Line. See under D. longipes for note on differences from that species.


Description (Barlow 1974)

Decaisnina djamuensis (Krause) Barlow, comb. nov.

Loranthus djamuensis Krause, Bot. Jahrb. 57: 478 (1922); Amylotheca djamuensis (Krause) Dans. Bull. Jard. bot. Buitenz. 11: 243, illus. Fig. 1, a-d (1931); Engl.& Krause, Pfl. Fam. ed. 2 16b: 139 (1935). Type.-Djamu (Ramu) River, 600 in alt., Schlechter 17319, 21.ii.1908 (B, holotype, photo in AD; s).

Elytranthe mamberamica Krause, Nov. Guin. 14:100 (1923). Type.-Mamberamo River, de Bruyn 222, 20.ii.1914 (B, holotype, photo in AD; L 926134910).

Glabrous except young stems and leaves sparsely or densely covered with irregular brown scales. Stems slightly flattened but not double edged when young, soon becoming terete. Petiole c. 1 cm long; lamina narrowly ovate to ovate, 8-14 by (2.5)-4-7 cm, dull on both sides, attenuate to abruptly contracted at the base, rounded at the apex but sometimes slightly attenuate; venation usually obscure except for the midrib (lateral veins sometimes distinct in thinner old leaves). Inflorescences 1 or 2 in leaf axils; axis more or less terete but enlarged at the nodes, bearing 6-9 pairs of triads, 3-6 cm long; peduncles of the triads 1-3 mm long; lateral flowers of the triads almost sessile but the pedicels 1-3 . 5 mm long in fruit; bracts rounded, more or less imbricate, 25 mm long. Calyx cylindrical to slightly urceolate, 35 mm long; limb flaring, entire, thin, 1 mm long. Corolla in the mature bud (15)-20-26 mm long, palecoloured; petals in the open flower usually free to the base but sometimes coherent in the lower 3 mm for some time after anthesis. Anthers 2.5 mm long, slightly longer than the free parts of the filaments. Style articulate (0.5)1.5-2 mm above the base, persistent on the fruit. Fruit urceolate, crowned by the persistent calyx limb.

Occurrence. New Guinea, from Biak to the Ramu R., and New Britain (Fig. 2), sea level to 1050 m altitude.

Representative Specimens. WEST IRIAN: Biak, near Buruku airstrip, c. 20 m alt., de Wilde 1203, 16.ix.1960 (L). EASTERN NEW GUINEA: Near Wigote Village, Lumi Subdist., Sepik Dist., 1000 m alt., Darbyshire 392, 9.ix.1961 (CANB; L). NEW BRITAIN: 7 miles SE. of Benim Village, Kandrian Dist., 300 m alt., Henty and Frodin NGF 27353, 23.iii.1966 (LAE; L).

See note under D. hollrungii.


Illustrations

Decaisnina djamuensis (as Amylotheca djamuensis). A - inflorescence. B - flower. C - fruit. D - longitudinal section of seed. From Danser (1936, Brittonia 2: 131-134).


Photographs


Specific Locality Information


Decaisnina djamuensis

updated 18 January 2007