Maesa brassii 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 : 250-252

Maesa brassii Sumanon & Utteridge , sp. nov. ( Fig. 3 )

Recognised in the genus Maesa by the combination of the following characters: scrambling habit, entire leaf margins and most parts conspicuously pubescent with striking, ginger-brown hairs together with scales, leaves drying dark sage-green adaxially and reddish brown abaxially, and cladodromous–eucamptodromus venation.

Type:— PAPUA NEW GUINEA. Milne Bay Province: north slopes of Mt. Dayman, Maneau Range [7°7’S, 146°36’E], 25 July 1953 (fr.), L. J. Brass 23676 (holotype K!; isotypes CANB!, L image!) .

Scrambler described as liana or climber to 10 m. Indumentum of hairs and scales: hairs 0.016–1.12 mm long, gingerbrown, giving a hirsute, hispid or pilose appearance throughout except the hypanthium; scaly on lamina surfaces, buds, inflorescences and fruits, scales peltate, up to 0.08 mm in diameter, creamy ginger, ± sessile, circular with irregular margins. Branches drying reddish brown with scattered indistinct lenticels, pilose, scaly to densely scaly on young parts. Leaves: lamina ovate, 3.0– 8.5 cm long by 1.5–5.0 cm wide, sub-coriaceous, drying dark sage-green above, reddish brown below, adaxial surface sparsely pilose and scaly, densely so when young, abaxial surface pubescent with all hair types and scales; base cuneate; margins entire; apex acute or sometimes emarginate; midrib drying reddish brown, glabrous adaxially, sometimes sparsely hairy in young leaves, hairy to densely hairy abaxially with all hair types and scales; secondary veins 6–7 pairs, cladodromous–eucamptodromus, indumentum as lamina; petiole 0.5–1.1 cm long, pubescent. Staminate inflorescences and flowers not seen. Pistillate inflorescences lateral (axillary), racemes, solitary, sometimes with first order branching, 7–11 cm long in fruit (not known at anthesis), axis hairy; pedicels 1.5–1.8 mm long, hispid and scaly; bracts triangular, 1.0– 1.25 mm long, hispid, margins entire, apex acute; bracteoles ±opposite, inserted at the base of the hypanthium, shape as bracts, hispid abaxially, 0.4–0.8 mm long, 0.1–0.2 mm wide. Pistillate flowers pentamerous; calyx lobes triangular, 0.6–0.9 long, 0.5–0.75 mm wide, hispid and scaly abaxially, margins entire to ciliate, apex acute; corolla not seen; hypanthium 1.0– 1.2 mm long, scaly to densely scaly; ovary 0.30–0.45 mm long, 0.7–0.9 mm diameter, style 0.2–0.3 mm long. Fruits globose, 2.5–3.5 mm long, 3.0– 3.5 mm diameter, sparsely scaly; pedicels in fruit 1.5–2.8 mm long; bracteoles remaining ±opposite each other at the base of the fruit; calyx lobes non-overlapping, persistent.

Distribution and ecology:— This species is currently known only from the type collection from Milne Bay Province, Papua New Guinea. The plant was found in rainforest at c. 700 m (fide Brass 1956: 133).

Etymology:— The epithet honours Leonard John Brass (1900–1971), an Australian-American botanist who collected the type specimen of this new species. He participated in several important expeditions to New Guinea, especially as the plant collector for the Archbold Expeditions, and collected many thousand specimens valuable for the study of New Guinea flora (c. 35,000 numbers – see Perry 1971).

Notes:— Maesa brassii is distinguished by its scrambling habit, being conspicuously hairy throughout with striking, ginger-brown hairs, entire leaf margins, and leaves drying dark sage-green adaxially and reddish brown abaxially. The indumentum of this species comprises both hairs of varying lengths and scales; the shortest hirsutellous hairs are found on the margins of the calyx lobes, while the longer hairs, giving a pilose appearance, cover almost all parts of the plant. The venation is quite distinct – the secondary veins branch quite early, usually just after halfway between the midrib and margin, and then diminish without clearly looping and joining and forming prominent marginal loops, somewhere between the cladodromus and eucamptodromus states of Hickey (1979).

From the key to the species provided by Sleumer (1987), M. brassii would key out to M. rufovillosa based on the combination of pentamerous flowers, pubescent leaves and the racemose, many-flowered inflorescences and, indeed, this collection was included within cited specimens of M. rufovillosa in Sleumer’s revision. Utteridge (2013: 684) discussed how Sleumer’s concept of M. rufovillosa was rather muddled and included a mixture of scrambling (‘climbing’) and shrubby/tree species, as well as species from primary or secondary habitats. With the description of M. brassii here, and the resurrection of M. ruficaulis from M. rufovillosa in Utteridge (2013), the limits of latter species are now more clearly defined: the sub-coriaceous leaves, drying dark sage-green adaxially and reddish brown abaxially, and the entire leaf margins make M. brassii very distinctive and easily separated from M. rufovillosa , which has chartaceous leaves with serrate margins, usually drying dark brown above and pale sandy-brown below and hispid hairs. Both species are found in rainforest, but M. rufovillosa seems to be scattered in lowland localities mostly near the coast. Unfortunately, there is currently only one collection of M. brassii making it difficult to determine the distribution and ecology of this species. Whilst there is no detailed label information, Brass (1956: 133) states his collections on this date were made from a camp at 700 m in a mixture of primary and secondary habitats at the junction between lowland rain forest and oak montane forests. More collecting is needed in the Owen Stanley Range in Papua New Guinea to better understand the ecology of M. brassii .

Figures

FIGURE 3. Maesa brassii Sumanon & Utteridge. A habit of fruiting plant; B node with petiole and inflorescence base; C abaxial surface of leaf; D part of infructescence; E fruit apex; F LS fruit (larger fruit than E, drawn at lower magnification); G scales on fruit surface; H scales and hairs on pedicel.All from Brass 23676 (K). Scale bars: single bar = 1 mm, graduated single bar = 2 mm and 5 mm, double bar = 1 cm, graduated double bar = 5 cm. Illustration by Andrew Brown.