Gossia aphthosa (Vieill. ex Brongn. & Gris) N. Snow

Snow, Neil, 2020, A revision of New Caledonian Gossia N. Snow & Guymer (Myrtaceae), Adansonia (3) 42 (7), pp. 131-177 : 139-140

Gossia aphthosa (Vieill. ex Brongn. & Gris) N. Snow

( Figs 4D-G ; 5 ; 13E-I )

Austrobaileya 8: 180 (2010). — Eugenia aphthosa Brongn. & Gris, Bulletin de la Société botanique de France 13: 469 (1865). — Austromyrtus aphthosa (Brongn. & Gris) Burret, Notizblatt des Botanischen Gartens und Museums zu Berlin-Dahlem 15: 504 (1941).

— Typus: New Caledonia. Grande Terre, South Prov ., Collines de Wagap , Vieillard 2172 (holo-, P [ P00602542 ]; iso-, A[A00255453, A00255454], B, BISH, G[G003410963, G00340964], L[3 sheets], MEL, P[P00602543], Z[Z-000050852]).

ETYMOLOGY. — Likely from the Greek aphtha, which is a reference to thrush (= mouth ulcers), coupled with the Latin suffix osa (“full of”). Aphthosa thus presumably refers to the ring of corky tissue at the base of the petioles.

DISTRIBUTION, HABITAT AND PHENOLOGY. — In three distinct regions areas on Grande Terre ( Fig. 5 ); in gallery forests and other humid to wet forests over ultramafics, schists, micaschists, and gneiss, 250- 500 m. Flowering August through February; fruiting September through June.

DESCRIPTION

Trees or shrubs

2- 8 m.

Branchlets

Terete to compressed; internodes> 5 mm.

Leaves

Coriaceous, 2 per node; petioles 2-4.8 mm, flat to terete; blades (8.5-)12.0-24.0 × (3.5-)6.6-13.0 cm, elliptic to broadly elliptic, base cordate (and sometimes amplexicaulous) to broadly rounded, surface flat, margin flat to somewhat revolute at edges, apex obtuse to somewhat acute, midnerve above sulcate, secondary veins flush above, oil glands of lower surface dense but indistinct.

Inflorescence

1.5-6 cm, of monads, triads, or few-flowered racemes, axillary or clustered on naked branches; pedicels 0.3-1.5 cm; extrafloral bracts lacking or scale-like.

Bracteoles

(1.5-) 3-4 mm, very narrowly ovate or elliptic to very narrowly obovate, sparsely sericeous.

Hypanthium

c. 1.5 × 1.5 mm, campanulate, surface smooth, glabrous to densely sericeous; ovary apex glabrous.

Calyx

Lobes 4 or 5, 1- 2 mm, broadly triangular, sparsely sericeous above, glabrous to sparsely sericeous below, green.

Petals

c. 5 × c. 4 mm, glabrous above and below, ciliate on margins.

Filaments

5-8 mm; anther sacs 0.4-0.5 mm.

Style

6-7 mm, glabrous to sparsely sericeous at base.

Berry

8-9 × 8-9 mm, globular, base rounded, green maturing becoming dark purplish to blackish; seed number unknown.

REMARKS

Gossia aphthosa can be distinguished among New Caledonian congeners by its relatively large, flat, and broadly rounded to cordate leaf bases and frequently cauliflorous inflorescences.The nominal subspecies has a prominent ring of corky tissue at the base of the petioles, which is unique in the genus (e.g., Snow et al. 2003). The three subspecies are based on differences in eco-geography and non-fixed, but mostly consistent differences in morphology. The inflorescence branches are said to be reddish on some specimens (e.g., MacKee 13229) and the leaves are said to emerge pinkish (MacKee 4427).

KEY TO THE SUBSPECIES OF GOSSIA APHTHOSA (VIEILL. EX BRONGN. & GRIS) N. SNOW

1. Base of petiole surrounded by prominent ring of corky tissue; hypanthium often silvery-sericeous (northern late Cretaceous micaschistes and gneiss, Massif du Panié, Northern Province) ................................................ ...................................................................................................................... Gossia aphthosa subsp. aphthosa

— Base of petiole without corky swellings; hypanthium mostly glabrous (northern Central Range basement Mesozoics ands schistes) ...................................................................................................................................... 2

2. Inflorescences 5-8 cm; leaf blades stiffly coriaceous, base strongly cordate and clasping; north-central humid forests ........................................ Gossia aphthosa subsp. longipedunculata N. Snow & Munzinger , subsp. nov.

— Inflorescence less than 6 cm; leaf blades coriaceous, base rounded or cordate and clasping; southeast humid forests over ultramafics ................ Gossia aphthosa subsp. austro-orientalis N. Snow & K. Gandhi , subsp. nov.

Figures

FIG. 4. — A-C, Gossia angustifolia N. Snow, sp. nov.: A, branch; B, inflorescence in part; C, flower with petals and stamens removed, and in longitudinal section at left; D-G, Gossia aphthosa (Vieill. ex Brongn. & Gris) N. Snow subsp. aphthosa: D, branch showing leaves with corky swellings at base of leaf and ramiflorous inflorescences; E, detail of corky swellings; F, detail of flower with reflexed petals; G, remnants of inflorescence in axil (with corky swellings) of dehisced leaf; H-J, Gossia bourailensis N. Snow, sp. nov.: H, branch with inflorescences; I, detail of flower bud; J, detail of flower with petals removed showing calyx lobes, staminal ring, hairy ovary apex, and style with proximal pubescence. Vouchers: A-C, MacKee 33461 (NOU); D, F, MacKee 28444 (P); E-G, MacKee 26722 (NOU); H-J, Balansa 1516a (P); K, Veillon 5958 (NOU); J, MacKee 5328 (P). Scale bars: A, D, E, G, H, 2 cm; B, 5 mm; C, F, I, J, 3 mm.

FIG. 5. — Distribution map for subspecies of Gossia aphthosa (Brongn. & Gris) N. Snow.

FIG. 13. — A-D, Gossia diversifolia N. Snow, sp. nov.: A, branch with flowers; B, detail of branchlet with quadrangular-winged young stems; C, flower in bud; D, immature fruit; E-I, Gossia aphthosa (Vieill. ex Brongn. & Gris) N. Snow subsp. longipedunculata N. Snow & Munzinger, subsp. nov.: E, leaves and terminal inflorescence; F, flower detail prior to anthesis;G, apical view of flower with staminal disk (petals and stamens removed);H, branch with leaves and inflorescence; I, maturing fruit. J, K, Gossia kaalaensis N. Snow, sp. nov.: J, branch with inflorescences, petiole (adaxial view) to right, raised adaxial leaf venation near margin (enlarged at upper left); K, immature fruit. Vouchers: A-C, MacKee 43897 (NOU); D, Jaffré 3228 (NOU); E-G, MacKee 26628 (NOU); H-I, MacKee 25749 (NOU); J, K, McPherson 2551 (P). Scale bars: A, J, 2 cm; B, 1 cm; C, D, K, 3 mm; E-G, I, 5 mm; H, 2 mm.