Monoon salomonicum I.M.Turner & Utteridge, 2017

Turner, Ian M. & Utteridge, Timothy M. A., 2017, Annonaceae in the Western Pacific: geographic patterns and four new species, European Journal of Taxonomy 339, pp. 1-44 : 6-9

Monoon salomonicum I.M.Turner & Utteridge sp. nov.

urn:lsid:ipni.org:names:77164166-1

Figs 3–4

Diagnosis

Differs from the other described species of Monoon from Melanesia in its relatively short and thick flower pedicels and broadly ovate, thick fleshy petals. Differs from M. pachypetalum sp. nov. in having a symmetrical leaf base and stipitate monocarps.

Etymology

The epithet alludes to the Solomon Archipelago to which the new species is endemic.

Type

SOLOMON ISLANDS: Santa Ysabel, Allardyce Harbour south side, 7°46'48'' S, 158°38'46'' E, primary forest by river in valley bottom, 24 Jan. 1964, Whitmore’s Collectors BSIP 3661 (holo-: K).

Additional specimens examined

PAPUA NEW GUINEA: Bougainville, Kapikavi, 6°27'39'' S, 155°39'14'' E, alt. 2500 ft, 3 Feb. 1967, P. Lavarack & C. Ridsdale NGF 31349 ( K).

SOLOMON ISLANDS: Choiseul, north-east Choiseul, Ologhata [Ologholata] Harbour, 7°18'45'' S, 157°24'13'' E, Hillside 350 feet, 31 Oct. 1969, I. Gafui et al. BSIP 17419 ( K); Kolombangara, 7°58'34'' S, 157°04'18'' E, river valley west of camp site, 4 Sep. 1965, Iromea R. S. S. 2530 ( K).

Description

Tree ca 9–12 m tall, to 20 cm dbh. Twigs drying dark brown, longitudinally wrinkled or lozenged, youngest parts with short brown adpressed tomentum, lost with age, sometimes with circular or ellipsoidal paler brown lenticels, flush or slightly raised. Innovations densely adpressed pale brown hairy. Leaves chartaceous, drying grey above, grey-brown below, midrib and lateral nerves flush above, raised below, adpressed brown hairs on midrib above and midrib and lateral nerves below, sometimes sparse; lamina ovate to ovate-lanceolate, 12–28 × 5–10 cm, apex acute or more commonly acuminate, base cuneate or less commonly truncate, lateral veins 10–11 pairs, visible from both surfaces, arching forward at ca 30–45° to the midrib, junction between laterals and midrib distinctly decurrent, in one specimen (R. S. S. 2530) including domatia with dense tufts of relatively long, erect pale brown hairs, tertiary venation sclariform to subscalariform, only visible from below; petioles drying blackish or dark brown, horizontally wrinkled, 6–10 mm long, 2–3 mm wide, often adpressed brown or pale hairy, lamina ultimately slightly decurrent running into two parallel ridges along margins of shallow channel on adaxial side of petiole. Inflorescences axillary, mostly to fallen leaves, peduncle inconspicuous, ca 2–3 mm long, 2–2.5 mm wide, adpressed brown hairy, longitudinally wrinkled, apparently only bearing 1–2 flowers at any one time. Flowering pedicel ca 8 mm long, 2 mm thick, adpressed brown hairy, longitudinally wrinkled; sepals 3, slightly connate at base, broadly ovate, ca 4 × 6 mm, apex obtuse, base truncate, thickly coriaceous, adpressed brown hairy outside, glabrous within; petals thickly fleshy, more than 1 mm thick when dry, broadly ovate, apex obtuse, outer petals ca 10 × 8 mm, verruculose outside but obscured by dense brown tomentum, inside with very short brown hairs on distal half, but glabrous proximally, drying black and wrinkled, inner petals ca 10 × 6 mm, similar to outer petals abaxially, inside with longer brown hairs near apex, otherwise glabrous, drying black or dark brown below with longitudinal grooves and warty surface near based; stamens many, ca 1 mm long, connective apex truncate, polygonal; carpels many, ca 1 mm long, pale brown hairy, stigma ca 1.5 mm long, apex acute, glabrous, pale hairy basally. Fruiting pedicel to 18 mm long, ca 3–4 mm thick, longitudinally striate, densely adpressed brown hairy, monocarps to ca 8, ellipsoidal, 2.5–3 cm long, ca 1.5 cm diameter, thin walled, drying dull black or dark brown, apiculate, verruculose, adpressed brown hairy most noticeably near apex and base, stipes 6–17 mm long, ca 2 mm thick. Seeds 1, ellipsoidal, ca 2.5 × 1.5 cm, pale brown with irregular circumferential groove.

Field notes

Bole crooked (BSIP 3661); bole: straight, buttresses: absent (BSIP 17419); bark surface grey, smooth (BSIP 3661); bark surface: dark brown, smooth (BSIP 17419); slash: wood and bark soft, white (BSIP 3661); slash, wood: soft, brownish white; slash, bark soft (BSIP 17419); flowers yellow, unscented (BSIP 3661); flowers greenish yellow (NGF 31349); fruits yellow (BSIP 3661); fruits: yellowish brown (ripe) (BSIP 17419); fruit orange (NGF 31349); fruits green (R. S. S. 2530).

Distribution and habitat

Papua New Guinea (Bougainville) and the Solomon Islands ( Fig. 4 ) in lowland to montane forest.

Conservation status

The species is known from four collections from four locations and is distributed throughout Bougainville and the northern part of the Solomon Islands. The EOO (excluding unsuitable habitat) can be estimated from the areas of Bougainville (9,318 km 2), Choiseul (3,837 km 2), Kolombangara (680 km 2) and northern Santa Isabel island (1,000 km 2), totalling 14,835 km 2 below the threshold for Vulnerable, and the AOO is only 16 km 2 within the Endangered criteria. Because of the very few localities and the continued forest

exploitation in the Solomon Islands, we give this species a provisional conservation rating of EN B2 ab(iii, iv).

Notes

There are at least two more species of Monoon from the Solomon Archipelago but the material available to us (BSIP 15202, BSIP 13474, Craven 537) is too limited to describe.

Figures

Fig. 3. Monoon salomonicum I.M. Turner & Utteridge sp. nov. A. Leafy twig. B. Domatia in axils of secondary nerves on leaf abaxial surface. C. Indumentum on adaxial surface of midrib. D. Example of more distinctly acuminate leaf apex. E. Branchlet bearing flower. F, G. Two views of flower, one attached, one detached. H. Fruiting pedicel bearing two monocarps. I. Monocarp with part of pericarp removed to expose seed. J. Transverse section of monocarp. Scale bars: graduated single bar = 2 mm; double bar = 1 cm; graduated double bar = 5 cm. Drawn from BSIP 3661 (A, C, E–J); RSS 2530 (B, D). Drawn by Andrew Brown.

Fig. 4. Map of the Solomon Archipelago showing the collecting localities of Monoon salomonicum I.M.Turner & Utteridge sp. nov.