Gossia clusioides (Brongn. & Gris) N. Snow Gossia clusioides, (BRONGN. & GRIS) N. SNOW

Snow, Neil, 2020, A revision of New Caledonian Gossia N. Snow & Guymer (Myrtaceae), Adansonia 42 (7), pp. 131-177 : 144-146

Gossia clusioides (Brongn. & Gris) N. Snow ( Figs 7-11 )

Austrobaileya 8: 180 (2010). — Eugenia clusioides Brongn. & Gris, Bulletin de la Société botanique de France 12: 180 (1865). — Austromyrtus clusioides (Brongn. & Gris) Burret, Notizblatt des Botanischen Gartens und Museums zu Berlin-Dahlem 15: 503 (1941). — Typus: New Caledonia. Grande Terre, South Prov ., Deplanche 525 (holo-, P [ P00602545 ]).

ETYMOLOGY. — Derived from the generic name Clusia L. ( Clusiaceae ) given the resemblance of its leaf blades to many species of that genus.

DISTRIBUTION, HABITAT AND PHENOLOGY. — Across much of Grande Terre ( Fig. 7 ); in humid or gallery forests over micaschistes, graywackes, or ultramafics, 10- 900 m. Flowering December to June; fruiting January to November.

DESCRIPTION

Trees or shrubs

(0.5-)3-9(-15) m tall.

Branchlets

Round to compressed; internodes> 5 mm.

Leaves

Coriaceous, 2 per node; petioles 3.5-20 mm, slightly sulcate; blades 7.0-18.5 × 2.5-12.0 cm, narrowly elliptic to broadly elliptic or obovate, base cuneate or rounded, surface flat to strongly bullate, margin flat to revolute, apex obtuse to sometimes retuse, midnerve above strongly sulcate, secondary veins flush to impressed above, oil glands of lower surface sparse to common but indistinct.

Inflorescence

90-160 mm; of monads, cymes, racemes, or panicles, terminal or axillary, pedicels 0.7-2.0 cm; extrafloral bracts leafy and pronounced when present but soon deciduous.

Bracteoles

6-7 mm, narrowly ovate to ovate, sparsely sericeous. Hypanthium

4-5 × 6-11 mm, campanulate, surface smooth, sparsely sericeous to sericeous (trichomes sometimes reddish at base); ovary apex glabrous.

Calyx

Lobes 5, 2.5-4.5 mm, broadly ovate to rounded, sericeous above (sometimes densely so), sparsely sericeous below, green.

Petals

9-11.5 × 7-9 mm, glabrous above, sericeous-tomentose below (trichomes reddish at base).

Filaments

6-8 mm; anther sacs 0.6-1.0 mm.

Style

Up to 9 mm, glabrous.

Fruits

7-17 × 7-15 mm, globular, base rounded to tapered, dark bluish-black; seeds 1-3.

REMARKS

Gossia clusioides has large flowers and small leafy bracts in the inflorescences that typically are soon caducous; the species also can be diagnosed by the strongly sulcate midveins on the upper leaf surface. It is one of several species in which the epidermis begins to crack into dark, irregularly rectangular flakes during the second year of growth.

Herbarium labels indicate that some members are slender and somewhat sparsely branched. Specimens with large (nonbullate) leaves might be confused with of G. aphthosa , but the flowers and fruits of G. clusioides are considerably larger.

The species has considerably more variation in leaf morphology than others of Gossia in New Caledonia. As treated here, Gossia clusioides comprises nine subspecies that are separated based primarily on differences in leaf dimensions and texture (smooth versus bullate), edaphic preferences, and often (but not always) geographic isolation. Some sites, however, have more than one subspecies. Much additional fieldwork is needed to further test the distinctness of the subspecies and to better understand their differences and distributions, especially given that these entities may be undergoing speciation.

KEY TO THE SUBSPECIES OF GOSSIA CLUSIOIDES (BRONGN. & GRIS) N. SNOW

1. Leaf blades moderately to strongly bullate ................................................................................................... 2

— Leaf blades flat (sometimes slightly bullate in subspp. clusioides and taomensis) ............................................ 5

2. Mature leaves (6.5-)7.0- 12.5 cm wide .......................................................................................................... ............................................... Gossia clusioides subsp. ploumensis (Däniker) N. Snow , comb. et stat. nov.

— Mature leaves 3.5-6.5 cm wide .................................................................................................................... 3

3. Leaves ovate to elliptic or broadly elliptic .................... Gossia clusioides subsp. maoyana N. Snow , subsp. nov.

— Leaves narrowly elliptic ............................................................................................................................... 4

4. Leaves 4-7 times longer than wide .......................... Gossia clusioides subsp. avanguiensis N. Snow , subsp. nov.

— Leaves 2-3(-4) times longer than wide .......................... Gossia clusioides subsp. bleuensis N. Snow , subsp. nov.

5. Leaves mostly elliptic to broadly elliptic or obovate (rarely narrowly elliptic in subsp. clusioides ) .................. 6

— Leaves narrowly elliptic ............................................................................................................................... 7

6. Leaf blades thickly coriaceous, upper surface often glossy, abaxially secondary veins often somewhat distinct, margin often strongly recurved nearly throughout; southwestern coast over ultramafics ................................. .......................................................................... Gossia clusioides subsp. callmanderiana N. Snow , subsp. nov.

— Leaf blades coriaceous, upper surface matte, abaxial secondary veins flush or distinct, margins flat to slightly recurved; across much of Grande Terre ......................................................... Gossia clusioides subsp. clusioides

7. Leaves obovate to elliptic, apex obtuse or (usually at least slightly) retuse ....................................................... ................................................................................. Gossia clusioides subsp. rembaiensis N. Snow , subsp. nov.

— Leaves narrowly elliptic, apex obtuse to broadly acute ................................................................................. 8

8. Petioles 2-7 mm long; leaves 3-6 cm long ................... Gossia clusioides subsp. taomensis N. Snow , subsp. nov.

— Petioles 8-20 mm long; leaves 9.5-17 cm long ........ Gossia clusioides subsp. tiebaghiensis N. Snow , subsp. nov.

Figures

FIG. 7. — Distribution map for subspecies of Gossia clusioides (Brongn. & Gris) N. Snow.

FIG. 8. — Typical leaf morphology for most subspecies of Gossia clusioides (Brongn. & Gris) N. Snow: A, G. c. subsp. bleuensis N. Snow., subsp. nov., with narrowly elliptic, bullate blades; B, G. c. subsp. maoyana N. Snow, subsp. nov., blades relatively narrow and bullate but longer than those of subsp. bleuensis; C, D, G. c. subsp. callmanderiana N. Snow, subsp. nov., blades elliptic and flat; E, G. c. subsp. rembaiensis N. Snow, subsp. nov.; F, G. c. subsp. clusioides; G, G. c. subsp. subsp. taomensis N. Snow, subsp. nov.; H, G. c. subsp. tiebaghiensis N. Snow, subsp. nov. Vouchers: A, McPherson 4001 (BISH); B, Dawson 16603 (WELTU)); C, Jaffré 1275 (BISH); D, Virot 1537 (BISH); E, McPherson 5083 (BISH); F, MacKee 25608 (NOU); G, Veillon 4828 (NOU); H, McPherson 3323 (NOU). Scale bar: 2 cm.

FIG. 9. — Gossia clusioides (Brongn.& Gris) N. Snow subsp.ploumensis (Däniker) N. Snow,comb.et stat. nov., showing peeling and cracking bark of branchlets. Voucher: Snow 9215, BISH (sheet 3 of 3). Scale bars: A, C, 2 cm; B, 1 cm.

FIG. 10. — Living specimens of Gossia clusioides: A, G. c. subsp. callmanderiana N. Snow, subsp. nov. vel aff.; B, G. c. subsp. bleuensis N. Snow, subsp. nov. vel aff.; C, G. c. subsp.ploumensis (Däniker) N. Snow, comb. et stat. nov.; D, G. c. subsp. ploumensis comb. et stat.nov. vel aff., but with larger and more prominently bullate leaves than normal and possibly representing an undescribed taxon. Vouchers: A, ©Hervé Vandrot, taken at Cascade la Pandanas-Koniambo in 2010 (http://endemia.nc); B, © Christian Létocart, taken at Yaté; C, ©Daniel & Irène Létocart, taken at Napoérédjeine in 2007; D, ©Jean-Louis Ruiz, taken at Pont des Japonais in 2005 (http://endemia.nc).

FIG. 11. — Living specimens of Gossia clusioides: A, G. c. subsp. avanguiensis N. Snow, subsp. nov. vel aff.; B, G. c. subsp. taomensis N. Snow, subsp. nov. Vouchers: A, ©Hervé Vandrot, taken at Naraja entre Ouaté et Ponérihoen (http://endemia.nc); B, Munzinger 3015; photo by J. Munzinger.