Maesa aurulenta Sumanon & Utteridge, 2021

Sumanon, Pirada, Eiserhardt, Wolf L., Balslev, Henrik & Utteridge, Timothy M. A., 2021, Six new species of Maesa (Primulaceae) from Papua New Guinea, Phytotaxa 505 (3), pp. 245-261 : 248-250

Maesa aurulenta Sumanon & Utteridge , sp. nov. ( Fig. 2 )

Recognised in the genus Maesa by the combination of the following characters: indumentum of short hairs and peltate scales, leaves with repand to sinuate leaf margins, relatively large leaves (11.5–18 cm long, 4.0– 6.8 cm wide) with petioles 0.5–1.0 cm long, and leaves drying olive-green above and tawny-brown below, and tetramerous flowers.

Type:— PAPUA NEW GUINEA. Milne Bay Province: Baniara Subdistrict, S of Opanabu village , approx. 10°1’S, 149°42’E, elev. 600– 700 m, 16 July 1969 (fr.), A. Kanis 1242 (holotype K!; isotypes A n.v., CANB!, L 2 -sheets [ L.2629941, L. 2629942] images!, LAE n.v.) .

Tree or treelet, 2–5 m high. Indumentum of hairs and scales: hairs short, less than 0.04 mm long, white, giving a hirsutellous appearance on the vegetative parts; scales peltate, up to 0.08 mm in diameter, pale ginger-brown with a central dark spot, ± sessile, circular. Branches drying reddish brown with scattered lenticels, hairs and scales lacking. Leaves: lamina lanceolate, 11.5–18 cm long, 4.0– 6.8 cm wide, chartaceous, ‘somewhat glossy, dark green above, pale grey-green below’ (fide Kanis 1242), drying olive-green above, shiny tawny-brown below, adaxial surface glabrous, abaxial surface scaly; base cuneate; margins repand or sinuate with 5 teeth on each side; apex attenuate; midrib sparsely hirsutellous adaxially, scaly abaxially; secondary veins 5–8 pairs, eucamptodromous, indumentum as lamina; petiole 0.5–1.0 cm long, glabrous. Staminate inflorescences and flowers not seen. Pistillate inflorescences lateral (axillary), racemes, solitary, 2.0– 3.5 cm long at anthesis, 2.0– 4.5 cm long in fruit, axis scaly (hairs lacking); pedicels 0.45–1.20 mm long, densely scaly distally; bracts ovate, 0.25–0.40 mm long, scaly to densely scaly, margins ciliate, apex acute; bracteoles ±opposite, inserted at the base of the hypanthium, ovate, 0.4–0.7 mm long, apex acute, margins ciliate, scaly. Pistillate flowers tetramerous, occasionally pentamerous, ‘greenish white’ (fide Kanis 1242); calyx lobes triangular, 0.4–0.6 mm long, 0.6–1.1 mm wide, scaly, margins ciliate, apex acute to rounded; corolla tube 0.5–0.7 mm long, corolla lobes 0.44–0.50 mm long, 0.54–0.70 mm wide; hypanthium 0.6–0.7 mm long, scaly; ovary 0.3–0.4 mm long, 0.56–0.70 mm diameter, style 0.18–0.30 mm long. Fruits ‘grey–green’ (fide Kanis 1242), ‘cream green’ (fide Schodde 5647), globose, 2.0– 2.8mm long, 2.0– 2.7 mm diameter, scaly to sparsely scaly (hairs absent); pedicels in fruit 0.75–1.25 mm long; bracteoles remaining ±opposite at the base of the fruit; calyx lobes overlapping, persistent.

Distribution and ecology:— Only known from Central and Milne Bay Provinces of Papua New Guinea. It has been collected from an elevation of 600–820 m, in gully forest or primary hill forest.

Etymology:— The epithet refers to the shiny, golden to tawny-brown colour of the abaxial leaf surface when dried, which caught our attention at first glance when looking at the type specimen of this species.

Additional material examined:— PAPUA NEW GUINEA. Central Province: Coastal scarp of Astrolabe Range, south-west of Birribi [9°32’S, 147°26’E], elev. c. 610 m, 27 August 1970, R. Schodde 5647 ( CANB 2 -sheets!, K!, L image!) . Milne Bay Province: Normanby Island [10°0’46’’S 151°0’37’’E], Mt. Pabinama, elev. 820 m, 2 May 1956 (fl. & fr.), Brass 25652 ( K!, L-image!); ibid., Fergusson Island [9°31’1’’S 150°40’29’’E], Mts between Agamola and Ailuluai, elev. 800 m, 12 June 1956 (fl. & fr.), Brass 27115 ( K!, L image!) .

Notes:— Maesa aurulenta keys to M. bismarckiana when using Sleumer’s key (1987) in respect of the tetramerous flowers and lepidote leaves (except for the hirsutellous adaxial midrib); both taxa can have hairs and scales, however, the combination of the following characters make it different from M. bismarckiana : the repand to sinuate leaf margins, leaves more than 11 cm long and 4 cm wide, lanceolate leaves, and the leaves drying olive-green above and shiny tawny-brown below. Maesa bismarckiana is widely distributed, and despite the recognition of this taxon, remains taxonomically problematic. Maesa aurulenta has been collected from lower elevations around 600–820 m [1968– 2690 ft], while M. bismarckiana s.s. specimens have been collected from an elevation of c. 760 m [2500 ft] and above. Maesa aurulenta is also similar to M. haplobotrys , but can be distinguished from that species by the eucamptodromous venation (cladodromous in M. haplobotrys ), a single raceme in each axil ( M. haplobotrys with multiple racemes in the same axil), and tetramerous or occasionally pentamerous flowers (pentamerous in M. haplobotrys ).

Figures

FIGURE 2. Maesa aurulenta Sumanon & Utteridge. A habit; B node with petiole and inflorescences; C abaxial surface of leaf; D hairs on abaxial midrib; E distal part of inflorescence; F pistillate flower, hydrated; G corolla from F, opened flat; H flower after removal of corolla and calyx lobe; I distal part of infructescence; J fruit apex; K fruit, lateral view after removal of one calyx lobe and part of proximal wall. A–D from Schodde 5647 (K) and E–K Kanis 1242 (K). Scale bars: single bar = 1 mm, graduated single bar = 5 mm (E and I) and 2 mm (J and K), double bar = 1 cm, graduated double bar = 5 cm. Illustration by Andrew Brown.