Maesa oblanceolatifolia 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 : 252-255

Maesa oblanceolatifolia Sumanon & Utteridge , sp. nov. ( Fig. 4 )

Recognised in the genus Maesa by the following combination of characters: obovate to oblanceolate leaves, entire leaf margins, pentamerous flowers on short pedicels (0.75–2.0 mm long) in simple, racemose and solitary inflorescences (not fasciculate) with more than 14 flowers.

Type:— PAPUA NEW GUINEA. Milne Bay Province: Neara Point, Cape Vogel Peninsula [9°41’S, 150°1’E], elev. 20 m, 7 April 1953 (fr.), L. J. Brass 21847 (holotype K!; isotypes A!, CANB!, L image!) .

Tree to 15 m tall. Indumentum: all parts lacking hairs, scaly on lamina surface, young buds, inflorescences and fruits; scales peltate, up to 0.08 mm in diameter, ginger-brown with a central dark part, ± sessile, circular usually with irregular margins. Branches drying dark brown with scattered lenticels, glabrous, scaly to densely scaly on young parts. Leaves: lamina obovate to oblanceolate, 4.8–7.2 cm long, 1.7–2.7 cm wide, sub-coriaceous, drying dark olive green above, tawny-brown below, adaxial surface scaly, abaxial surface scaly to densely scaly; base attenuate; margins entire; apex obtuse or sometimes acute; midrib ‘reddish’ (fide Frodin UPNG 994), glabrous both adaxially and abaxially; secondary veins 7–9 pairs, semicraspedodromous, indumentum as lamina; petiole 0.4–0.8 cm long, glabrous. Staminate inflorescences lateral (axillary), racemes, solitary, 3–6 cm long at anthesis, axis sparsely scaly; pedicels 0.75–2 mm long, scaly; bracts ovate, 0.60–0.75 mm long, scaly to densely scaly, margins entire, apex acute; bracteoles ±opposite, inserted at the base of the hypanthium, 0.4–0.6 mm long, 0.32–0.50 mm wide, shape as bracts. Staminate flowers pentamerous, ‘creamish’ (fide Womersley & Millar NGF 7843); calyx lobes ovate, 0.4–0.6 by 0.4–0.6 mm, glabrous, margins entire to ciliate, apex acute; corolla tube 0.6–0.7 mm long, corolla lobes 0.4–0.6 mm long, 0.5–0.8 mm wide, glabrous; stamens epipetalous, arising c. 0.16–0.24 mm from the base of the corolla; anthers dorsifixed, 0.30–0.35 mm long; filaments 0.20–0.32 mm long; hypanthium c. 0.36 mm long, scaly; ovary 0.12–0.40 mm long, 0.6–0.8 mm in diameter, style c. 0.20 mm long. Pistillate inflorescences lateral (axillary), racemes, solitary, 3.5–7.0 cm long at anthesis, 3.5–8.0 cm long in fruit, axis scaly; pedicels 1.0– 2.5 mm long, densely scaly distally; bracts ovate to triangular, 0.5–0.6 mm long, scaly to densely scaly, margins entire, apex acute; bracteoles ±opposite, inserted at the base of the hypanthium, shape as bracts, 0.6–0.7 mm long, 0.30–0.45 mm wide. Pistillate flowers pentamerous, ‘brown’ (fide Brass 24413), ‘white’ (fide Brass 21847); calyx lobes ovate, 0.64–0.90 mm long, 0.50–0.75 mm wide, glabrous, margins entire to ciliate, apex acute to rounded; corolla tube 0.64–0.90 mm long, corolla lobes 0.48–0.75 long. 0.50–0.75 mm wide; hypanthium 0.3–0.6 mm long, scaly; ovary 0.3–0.45 mm long, 0.6–0.9 mm diameter, style 0.2–0.3 mm long. Fruits globose, 2.4–2.7 mm long, 2.2–2.8 mm diameter, scaly; pedicels in fruit c. 1 mm long; bracteoles remaining ±opposite each other at the base of the fruit; calyx lobes partly overlapping, persistent.

Distribution and ecology:— Distributed in Milne Bay and Morobe Province. The species is common in rainforest, including along rivers at low elevation. Also collected from eucalypt savannah at 2200 ft [c. 670 m] (Paijmans 74).

Etymology:— The epithet refers to the oblanceolate leaves of the species. The oblanceolate leaf shape is consistent across all of the examined specimens is distinct from the lanceolate leaves of M. haplobotrys - this first drew our attention to this set of specimens during our work on the limits of that complex species as part of our revision of the genus in New Guinea.

Additional material examined:— PAPUA NEW GUINEA. Milne Bay Province: Bolu Bolu, Goodenough Island [9°28’S, 150°21’E, elev. 20 m, 28 September 1953 (fl. & fr.), L. J. Brass 24413 ( A!, CANB!, K!, L image!); Goodenough Island , east slopes, rocky banks of stream in rainforest [9°20’S, 150°14’E] elev. 150 m, 1 November 1953 (fl.), L. J. Brass 25113 ( A!, L image!); Kiriwina Island [8°25’S, 151°4’E], 28 October 1972 (fr.), D. G. Frodin UPNG 994 ( K!, L image!); Central Kitava Island , 8°30’S, 151°5’E, elev. sea level, 4 October 1966 (fl.), A. Gillison NGF 25313 ( CANB!, K!, L image!); Normanby Island , Dauilele River , E Sewa Bay , 9°59’S, 150°47’E, 8 April 2008 (fl.), R. J. Johns 11299 ( K!); Fergusson Island , South of Mapamoiua , 9°37’S, 150°26’E, March 2009 (fl.), R. J. Johns 12890 ( K!); Alotau, 10°20’S, 150°25’E, elev. 750 m, 28 August 1979 (fl.), A. Kairo 107 ( K 2 -sheets!, L image!) ; Morobe Province: Wau, Bulolo, Compound 14, 7°10’S, 146°40’E, elev. 800 m, 17 May 1977 (fl.), B. Conn & A. Kairo 146 ( CANB!); Finschhafen Subdistrict , Sialum–Kalasa road 8 km from Sialum , 6°07’S, 146°37’E, elev. 350 m, 28 May 1975 (fl.), E. E. Henty & P. Katik NGF 49782 ( CANB!); Finschhafen, 6°35’S, 147°50’E, elev. 5 m, 4 July 1978 (fr.), K. Rau 369 ( CANB!, K!, L image!); Wampit [7°S, 146°35’E], elev. 1210 m, 30 August 1979 (fl.), K. Rau 426 ( CANB!, K!); Wau, Salamaua Road, Kaisenik, Upper Bulolo Valley , 7°10’S, 147°E, elev. 3500 ft [c. 1065 m], 30 December 1955 (fl.), J. S. Womersley & A. Millar NGF 7843 ( K!, L image!) ; Northern Province: Oro, SW of Safia, near Auwaka Village [9°42ʹ44’’S, 148°27’35ʺE], 3 September 1963 (fr.), K. Paijmans 74 ( CANB!) .

Notes:— Maesa oblanceolatifolia is similar to M. haplobotrys , and several of the collections of this new species were previously placed in that taxon by Sleumer (1987), and several collections of this taxon were also placed in Sleumer’s (1987) ‘collections not named’. However, Sleumer (1987) adopted a very broad circumscription of M. haplobotrys based on floral merosity (“flowers all (or for the greater part in the same specimen) 5-merous”), glabrous leaves and simple racemes. As a consequence of Sleumer’s species concept, numerous collections of Maesa collected from New Guinea and nearby islands were identified as M. haplobotrys even though they showed a variety of leaf morphology. Therefore, during our ongoing revision of the genus in New Guinea, the species limits of M. haplobotrys have been critically revised.

The specimens assigned to M. oblanceolatifolia differ from the common and widespread form of M. haplobotrys (which more closely corresponds with the type of M. haplobotrys from Queensland, Australia) in the sub-coriaceous, obovate-oblanceolate and smaller (up to 7.2 cm long) leaves (vs chartaceous, lanceolate and greater than 7.5 cm long of M. haplobotrys ).

The leaf characters of M. oblanceolatifolia are superficially similar to M. beamanii Utteridge (2000: 443) but may be distinguished by flower and inflorescence characters: pentamerous flowers and inflorescences with more than 14 flowers in M. oblanceolatifolia , tetramerous flowers and inflorescences with 2–6 flowers in M. beamanii . In addition, this new species is similar to M. pusilliflora described in this paper but differs by the ovate calyx lobes (triangular calyx lobes in M. pusilliflora ) and shorter (0.3–0.6 mm long) hypanthium (hypanthium 0.7–1.0 mm long in M. pusilliflora ).

Figures

FIGURE 4. Maesa oblanceolatifolia Sumanon & Utteridge. A habit; B two nodes with petioles and inflorescences; C abaxial surface of leaf; D part of inflorescence; E flower, hydrated; F corolla from E, opened flat; G off centre LS of flowers in E after removal of corolla; H scales on pedicel; I scales on fruit wall; J part of infructescence; K fruit apex; L LS of fruit. A–C, H–L from Johns 12890 (K); D–G Brass 24413 (K). Scale bars: single bar = 1 mm, graduated single bar = 5 mm (D and J) and 2 mm (K and L), double bar = 1 cm, graduated double bar = 5 cm. Illustration by Andrew Brown.