Maesa brevipedicellata Sumanon & Utteridge, 2020

Sumanon, P., Eiserhardt, W. L., Balslev, H. & Utteridge, T. M. A., 2020, Maesa brevipedicellata (Primulaceae), a new species from Papua New Guinea, Blumea 65 (1), pp. 83-85 : 83-85

Maesa brevipedicellata Sumanon & Utteridge , sp. nov. — Fig. 1

Unique in the genus Maesa is the self-supporting habit of being a shrub or small tree with hispid hairs throughout,lacking scales,the paniculate inflorescence and the very short pedicels, 0.4–1 mm long. This suite of characters also differentiates it from the morphologically similar species, M. rufovillosa , a climber,but, in addition, M. brevipedicellata differs from that species in more secondary vein pairs per leaf, 10–12 pairs (6–9 pairs in M. rufovillosa ) and the paniculate inflorescences with more than 100 flowers per inflorescence (unbranched racemose inflorescences with 10–60 flowers per inflorescence, to rarely a panicle in M. rufovillosa ). — Type: NGF (Yakas Lelean) 46396 (holo K; iso AAU, BISH, CANB.00708032, CANB.236149, L.2637084, L.2637085), Papua New Guinea, Central District , Tapini Sub-District, Tapini area, S8°18' E146°48', c. 3 000 ft [c. 915 m] alt., 1–4 May 1971 .

1 Department of Biology, Aarhus University, Aarhus C, 8000, Denmark.

2 Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AB, United King- dom.

Etymology. The species epithet ‘ brevipedicellata ’ refers to its very short pedicels (0.4–1 mm long), which sometimes make the flowers seemingly sessile.

Shrubs or small trees, up to 3 m tall. Indumentum of simple hairs, up to 1 mm long, ginger-brown, giving a hispid appear- ance throughout (see description of specific structures for distribution); scales absent. Branches drying reddish brown with sparsely scattered lenticels, hispid. Leaves: lamina ovate, 11.4–20 by 5–9.3 cm, chartaceous, drying fuscous above, tawny-brown below, adaxial surface sparsely hairy, abaxial surface hairy to densely hairy; base obtuse to cuneate, rarely subcordate; margins serrate, with 14–26 papilliform teeth per side; apex acute to attenuate; midrib drying yellowish to reddish brown, hispid both adaxially and abaxially; secondary veins 10–12 pairs, semicraspedodromous, indumentum as lamina; petiole 1.2–3.2 cm long, hispid. Staminate inflorescences and flowers not seen. Pistillate inflorescences lateral (axillary), panicles, 5–11 cm long, axis hispid; bracts ovate to triangu- lar, 1.1–1.5 mm long, hairy, margins entire, apex acuminate. Pistillate flowers pentamerous; pedicels 0.4–1 mm long; bracteoles ± opposite, inserted at the base of hypanthium, 0.8–1 by 0.4–0.75 mm, shape as bracts; calyx lobes ovate, 0.6–0.9 by 0.8–1 mm, hairy, margins entire, apex acute; corolla tube 0.6–1 mm long, lobes 0.5–0.75 by 0.6–1.3 mm; staminodes 5, filaments 0.5–0.7 mm long, anthers 0.16–0.2 mm long; hypanthium 0.5–0.8 mm long, hairy; ovary c. 0.2 by 0.9–1 mm, style c. 0.6 mm long. Fruits indehiscent, globose, 2.2–4.2 mm long, 2–4 mm diam; bracteoles remaining ± opposite each other at the base of the fruit; persistent calyx-lobes partly overlapping. Seeds many, angular, dark brown.

Distribution & Ecology — New Guinea (Morobe and Central Prov.).

Habitat & Ecology — The species has been collected in regrowth forest at 900–2200 m altitude. Flowering: January, February, May, June; fruiting: January, February, May, June, August.

Conservation assessment — Maesa brevipedicellata is assessed here as Vulnerable following the categories and criteria of IUCN (2012). The species is known from six collections from Morobe and Central Provinces in Papua New Guinea with an Ex- tent of Occurrence of 15 431.928 km 2 and an Area of Occupancy of 24 km 2 calculated using a grid cell of 2 km 2 in GeoCat ( Bachman et al. 2011). Whilst New Guinea remains relatively well forested, habitat conversion in Morobe Province, especially around the Lae area, has been well documented in Pipoly III & Takeuchi (2004), and taking into account this observed decline in quality of habitat, together with the EOO and AOO thresholds, and that the most recent specimens are from the 1970s, we assess this species as Vulnerable: VU B1ab(i, ii, iii) + B2ab(i, ii, iii).

Additional specimens seen. PAPUA NEW GUINEA (PNG), Morobe,vicinity Bu- lung R ., Nomauenem camp, S6°37' E147°33', 3000–5000 ft [c. 915–1525 m] alt., 28 Jan. 1937, J . Clemens & M . S . Clemens 5205 ( K) ; Morobe, Kaisenik , S7°20' E146°40', 2200 m alt., 1 Feb.1978, Kairo 51 ( K) ; Morobe, Kasanombe, road to Momsalom Village, Lae , S6°45' E147°10', 1700 m alt., 30 Aug. 1973, NGF ( P. Katik & K. Taho) 37926 ( BISH, CANB, K, M) ; Central, Goilala , between Kuputivava and Omoretu, S8°20' E147°00', 6500 ft [c. 1980 m] alt., 13 Feb. 1964, T . G . Hartley 13036 ( CANB, K) ; Morobe, vicinity Kikiepa Village near Wantoat Patrol Post,southern slope of Finisterre Mts , S6°10' E146°30', c. 5000 ft [c. 1525 m] alt., 2 June 1960, NGF ( J. S. Womersley & R. F. Thorne) 12721 ( A, CANB) .

Notes — Maesa brevipedicellata is unique in the genus with a diagnostic combination of characters including the self-supporting habit (tree), indumentum of hispid hairs but the absence of scales, the presence of paniculate inflorescences and pentamerous flowers.

Almost all specimens included as the new species described here, except NGF (J.S. Womersley & R.F. Thorne) 12721, were determined as M. rufovillosa by Sleumer. Sleumer described the habit of M. rufovillosa as a ‘bushy shrub, often scandent’ and included in the description, as noted in specimen collected by Lelean, NGF 46396, as ‘sometimes starting as a liana, ending in a small tree’ ( Sleumer 1987). This description makes the identification confusing. Based on our observations, plants in this genus can be clearly divided into two habit types: self-supporting (shrubs or trees) or non-self-supporting (described as scramblers, climbers or lianas). Maesa rufovillosa is a non-self-supporting species morphologically very similar to M. muelleri Mez (see Utteridge 2013), and, therefore, the specimens previously determined as M. rufovillosa by Sleumer, but having a self-supporting habit, are to be excluded from the true M. rufovillosa and described as the new species here.

In the revision of Sleumer (1987), many confusing collections were included under the name M. rufovillosa ; however, field and herbarium observations showed that some collections with a shrub habit are distinctive enough to be a separate species, M. ruficaulis S.Moore (detailed in Utteridge 2001: 680, 2013: 683). The morphology of M. brevipedicellata is unlikely to be confused with M. rufovillosa even though they share the same floral merosity and indumentum with the habit being especially diagnostic, see the diagnostic description for further differences. Compared to the other self-supporting Maesa species in New Guinea, M. brevipedicellata is most similar to M. ruficaulis , but differs from that species in lacking a flexuous axis of the inflorescences ( M. ruficaulis : inflorescence axis strongly flexuous), ovate leaf blades with acute to attenuate apex ( M. ruficaulis : leaf blades elliptic to elliptic-oblong with apex attenuate to acuminate), margin serrate with 14–26 papilliform teeth on each side of leaf ( M. ruficaulis 6–15 teeth).

Figures

Fig. 1 Maesa brevipedicellata Sumanon & Utteridge. a. Habit, showing stem with scattered lenticels; b. leaf node with base of peduncle; c. detail of stem indumentum;d. abaxial leaf margin; e. branch of inflorescence; f. open flower,side view;g. calyx;h. inner face of corolla opened up; i. branch of infructescence; j. mature fruit, side view; k. mature fruit, apical view; l. off-centre section through fruit (all NGF 46396). — Drawing by Andrew Brown. — Scale bars: a = 5 cm; b, d = 1 cm; c, f–h = 1 mm; e, i = 5 mm; j–l = 2 mm.