Gossia N. Snow & Guymer

Snow, Neil, 2020, A revision of New Caledonian Gossia N. Snow & Guymer (Myrtaceae), Adansonia 42 (7), pp. 131-177 : 133-135

Genus Gossia N. Snow & Guymer

DISTRIBUTION. — Gossia is widespread across Grande Terre in New Caledonia and occasional on adjoining islands, but so far is unreported for the Loyalty Islands; mostly in maquis or more mesic forests and species rarely occurring in dense or extensive populations; near sea level to 1500 m.

GENERIC DESCRIPTION OF GOSSIA

Plants

Shrubs to large trees, (0.2-) 0.5- 18 m.

Branchlets

Terete, compressed, or rarely 4-angled.

Colleters

Absent to obscure, reddish and hair-like if present.

Leaves

2(-3-4) per node, pedicellate or sometimes sessile, venation brochidodromous, thinly to thickly coriaceous, blades flat or bullate.

Inflorescence

Axillary, terminal or ramiflorus, of monads, racemes, or panicles, solitary, paired, or fascicled; extrafloral bracts absent, scale-like or sometimes leafy.

Bracteoles

2, sometimes early caducous.

Hypanthium

Campanulate, cupulate, obconic, or urceolate, not prolonged beyond ovary apex, smooth or sometimes ribbed or rugose; ovary apex glabrous to hairy.

Flowers

4-5(-8)-merous.

Locules

(1-)2(-3), placentation axile (or basal in G. angustifolia sp. nov.). Stamens numerous; filaments dorsifixed or subdorsifixed. Stigma apex terete, narrow to slightly globular.

Fruit

Baccate, green (immature) to yellow-orange or red but usually purplish-black at maturity.

Seeds

1-4(-12), testa hard, irregularly rounded and typically somewhat compressed with some angular edges; embryo coiled or less commonly C-shaped. Chromosome numbers unknown.

ARTIFICIAL KEY TO THE NEW CALEDONIAN SPECIES OF GOSSIA N. SNOW & GUYMER

1. Branchlets 4-angled (check youngest material) ............................... G. diversifolia (Brongn. & Gris) N. Snow

— Branchlets rounded or compressed .............................................................................................................. 2

2. Leaf blades blades broadly linear to very narrowly elliptic, apex retuse ......................................................... 3

— Leaf blades broader than narrowly elliptic, apex obtuse to acute (rarely retuse) ............................................ 5

3. Leaves 4 per node, blades broadly linear to very narrowly obovate ............... G. virotii (Guillaumin) N. Snow

— Leaves 2(-3) per node, blades narrowly elliptic to broader ........................................................................... 4

4. Leaves thickly coriaceous, margins strongly revolute; internodes at branch tips mostly less than 5 mm long ... .............................................................................. G. conspicua (Vieill. ex Guillaumin) N. Snow , comb. nov.

— Leaves coriaceous, margins flat to only slightly revolute; internodes at branch tips mostly greater than 5 mm long ............................................................................................. G. alaternoides (Brongn. & Gris) N. Snow

5. Flowers all or mostly 4-merous .................................................................................................................... 6

— Flowers all or mostly 5-merous .................................................................................................................. 10 6. Leaf blades (8.5-) 12 cm or longer ......................... G. aphthosa (Vieill. ex Brongn. & Gris) N. Snow (in part)

— Leaf blades less than 9.5 cm ........................................................................................................................ 7

7. Leaf blades mostly 6-9.5 cm ........................................................................ G. angustifolia N. Snow , sp. nov.

— Leaf blades mostly <6 cm ........................................................................................................................... 8

8. Leaf base narrowly cuneate; petiole sometimes drying nearly black ............ G. nigripes (Guillaumin) N. Snow

— Leaf base rounded to cordate and conduplicate; petiole drying brownish .................................................... 9

9. Leaf blade conduplicate only at base, surface flat to slightly undulate; apex of inflorescence rigid, not nodding ..................................................................................................................... G. bourailensis N. Snow , sp. nov.

— Leaf blade conduplicate up to half or more of its length, surface moderately to strongly undulate; apex of inflo- rescence sometimes nodding ...................................................................... G. conduplicata N. Snow , sp. nov.

10. Petals> 9 mm ........................................................................................................................................... 11

— Petals <9 mm (petals unknown in G. conduplicata N. Snow , sp. nov., which probably keys here) ............. 13

11. Base of leaf cordate to rounded; petiole 1.5-2 mm ..........................................................................................

........................................................ G. aphthosa subsp. longipedunculata N. Snow & Munzinger , subsp. nov. — Base of leaf round to cuneate, petiole 2-30 mm ......................................................................................... 12

12 Calyx lobes sparsely sericeous above; petals sericeous-tomentose below (sometimes densely so); hypanthium surface smooth; leafy bracts along inflorescence axis prominent (but typically soon caducous) ........................................ ......................................................................................................... G. clusioides (Brongn. & Gris) N. Snow

— Calyx lobes sparsely ciliate only on margins; petals minutely ciliate apically but otherwise glabrous below; hypanthium surface sometimes slightly ribbed; leafy bracts along inflorescence mostly absent ........................... ............................................................................................................. G. colnettiana (Guillaumin) N. Snow

13. Base of leaf blade moderately to strongly conduplicate, blade surface undulate ............................................... .................................................................................................................... G. conduplicata N. Snow , sp. nov.

— Base of leaf blade more or less flat (slightly conduplicate in G. katepahiensis N. Snow , sp. nov.), surface mostly flat ............................................................................................................................................................ 14

14. Leaf blades mostly 10 cm or longer .......................................................................................................... 15

— Leaf blades mostly 10 cm or shorter ......................................................................................................... 16

15. Base of petiole sometimes encircled by a corky ring; base of leaf blade cordate to rounded, sometimes clasping; lowermost inflorescences often ramiflorous below leaves; bracteoles very narrowly elliptic to very narrowly obovate ...................................................... G. aphthosa (Vieill. ex Brongn. & Gris) N. Snow (in part)

— Base of petiole lacking corky outgrowths; base of leaf rounded or cuneate, never clasping; lowermost inflorescences axillary; bracteoles narrowly ovate to ovate............................... G. clusioides (Brongn. & Gris) N. Snow

16. Leaf surface bullate (sometimes strongly) or margins strongly and irregularly undulate; bark of second and third year growth often dark and breaking in irregular rectangle patches ............................................................ 17

— Leaf surface smooth or margins to flat or somewhat undulate; bark of second and third year growth mostly somewhat smooth, grayish-brown (or dark and flaking in G. kuakuensis or G. pancheri (Brongn. & Gris) N. Snow ) .......... 18

17. Leaf margins more or less flat; lowermost inflorescences axillary, extrafloral bracts of inflorescence leafy; hypanthium sparsely sericeous in flower; petals sericeous to tomentose below .......................................................... ........................................................................................... G. clusioides (Brongn. & Gris) N. Snow (in part)

— Leaf margins irregularly undulate; lowermost inflorescences on naked branches below leaves, extrafloral bracts absent or scale-like; hypanthium sparsely to moderately sericeous in flower; petals ciliate ............................... ......................................................................................................................... G. ramiflora N. Snow , sp. nov.

18. Leaf apex mostly retuse (rarely obtuse) ...................................................................................................... 19

— Leaf apex obtuse to acute ........................................................................................................................... 20

19. Hypanthium c. 3 mm; bracteoles and calyx lobes sparsely to densely sericeous; leaves 2 per node ................... .......................................................................................................... G. pancheri (Brongn. & Gris) N. Snow

— Hypanthium 2.0- 2.5 mm; bracteoles and calyx lobes hairy; leaves 2 or 3 per node ......................................... ...................................................................................................... G. alaternoides (Brongn. & Gris) N. Snow

20. Calyx lobes drying mostly whitish or cream-colored (“petaloid” of some authors) ..................................... 21

— Calyx lobes drying mostly greenish ............................................................................................................ 22 21. Leaves mostly over 8 cm long, apex acute; adaxial leaf surface somewhat glossy, secondary veins prominently raised; margin somewhat undulate ................................................................. G. kaalaensis N. Snow , sp. nov.

— Leaves mostly shorter than 7 cm long, apex obtuse; adaxial leaf surface matte, secondary veins flush; margin slightly revolute ...................................................................................... G. ouazangouensis N. Snow , sp. nov.

22. Leaf base cordate or round ........................................................................................................................ 23

— Leaf base cuneate to narrowly cuneate ....................................................................................................... 27

23. Hypanthium sparsely to moderately sericeous ........................................................................................... 24

— Hypanthium glabrous or very sparsely sericeous near apex ........................................................................ 25

24. Extrafloral bracts of inflorescence leafy; bracteoles c. 3.5 mm long; petals 8-13 mm ....................................... .............................................................................................................. G. colnettiana (Guillaumin) N. Snow

— Extrafloral bracts of inflorescence leafy; bracteoles scale-like, 0.5-1.4 mm long; petals (4-) 5-7 mm ............. ........................................................................................................ G. vieillardii (Brongn. & Gris) N. Snow

25. Older branchlets with dark, rectangular flakes; extrafloral bracts of inflorescence leaf-like ..............................

.................................................................................................................... G. kuakuensis (Baker f.) N. Snow — Older branchlets smooth; extrafloral bracts of inflorescence lacking or small and scale-like ........................ 26

26. Petioles 1-3 mm, rounded above; leaf apex broadly acute to obtuse; ovary apex hairy ..................................... ..................................................................................................................... G. bourailensis N. Snow , sp. nov.

— Petioles 2.5-4 mm, sometimes slightly sulcate; leaf apex broadly rounded or slightly retuse; ovary apex gla- brous........................................................................................................... G. katepahiensis N. Snow , sp. nov.

27. Secondary veins on adaxial leaf (in sicco) surface prominently raised ......................................................... 28

— Secondary veins on adaxial leaf surface (in sicco) flush or only slightly raised ............................................ 29

28. Leaves elliptic, apex rounded (occasionally retuse); hypanthium sericeous, oil glands of uniform size; ovary apex densely tomentose ............................................................................. G. pancheri (Brongn. & Gris) N. Snow

— Leaves narrowly elliptic to narrowly ovate or somewhat elliptic, apex acute; hypanthium mostly glabrous, oil glands large and small; ovary apex glabrous .................................................... G. kaalaensis N. Snow , sp. nov.

29. Oil glands on abaxial leaf surface absent to sparse; style villous lower ½-¾, sometimes densely so; base of fruit

rounded or often prominently tapered ............................................ G. vieillardii (Brongn. & Gris) N. Snow — Oil glands on abaxial leaf surface dense; style sericeous to tomentose; base of fruit rounded ...................... 30

30. Hypanthium sericeous ............................................................................. G. mandjeliaensis N. Snow , sp. nov.

— Hypanthium glabrous ............................................................................................................................... 31

31. Petioles reddish (drying dark brown); mature leaves mostly 5.0 cm or longer, surface flat, margin slightly recurved; Île des Pins ............................................................................................ G. ngaensis N. Snow , sp. nov.

— Petioles dark red (drying nearly black); mature leaves mostly 4.5 cm or shorter, blades undulate, margin flat; Massif du Panié ......................................................................................... G. nigripes (Guillaumin) N. Snow