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Phytotaxa 505 (3): 245–261
https://www.mapress.com/j/pt/
Copyright © 2021 Magnolia Press Article PHYTOTAXA
ISSN 1179-3155 (print edition)
ISSN 1179-3163 (online edition)
Accepted by Emily Gillespie: 12 May 2021; published: 1 Jun. 2021
https://doi.org/10.11646/phytotaxa.505.3.1
245
Six new species of Maesa (Primulaceae) from Papua New Guinea
PIRADA SUMANON1,2,3, WOLF L. EISERHARDT1,2,4, HENRIK BALSLEV1,5 & TIMOTHY M.A. UTTERIDGE2,6
1 Department of Biology, Aarhus University, Building 1540, Ny Munkegade 116, DK-8000 Aarhus C, Denmark
2 Herbarium, Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AB, United Kingdom
3
pirada.sumanon@bio.au.dk; http://orcid.org/0000-0001-7247-8255
4
wolf.eiserhardt@bio.au.dk; http://orcid.org/0000-0002-8136-5233
5
henrik.balslev@bio.au.dk; http://orcid.org/0000-0002-7101-7120
6
t.utteridge@kew.org; https://orcid.org/0000-0003-2823-0337
Abstract
Six new species of Maesa (Primulaceae-Maesoideae) from Papua New Guinea, namely M. angustibracteolata, M. aurulenta,
M. brassii, M. oblanceolatifolia, M. pusilliflora and M. prolatifructa are described and illustrated based on observations from
herbarium specimens; the taxonomic affinities of each species are also discussed.
Keywords: Ericales, Malesia, Myrsinaceae, Papua New Guinea, Papuasia, taxonomy
Introduction
Maesa Forsskål (1775: 66) is a genus of shrubs, trees or scramblers traditionally placed in the Myrsinaceae, or sometimes
the monogeneric Maesaceae (e.g. Anderberg et al. 2000), but it is now included in an enlarged Primulaceae, including
two other previously recognised tropical families, Myrsinaceae and Theophrastaceae. Maesa is the sister group to all
other genera of Primulaceae (APG III 2009).
The genus was last monographed by Mez (1902) who recognised 102 species, but currently there are 178 accepted
species (POWO 2020) – all distributed in the Old World tropics from southern Africa through to the islands of the
Pacific. In New Guinea, 26 species (including species from the Moluccas and Solomon Islands) were recognised by
Sleumer (1987), but several new species have since been described (see Utteridge 2000; 2001; 2003; 2015), especially
as a result of extensive fieldwork and observations of Indonesian New Guinean taxa during the Mt Jaya checklist
project (Johns et al. 2006). Currently, there are 26 species described for New Guinea (Cámara-Leret et al. 2020), with
the inclusion of the taxa described here, there will be at least 32 recognised species of Maesa for the island. The genus
is currently being revised in New Guinea, and several populations, in a wide range of habitats exhibiting a variety of
morphological types, may merit recognition as distinct taxa, perhaps resulting in an additional five species for New
Guinea (Sumanon et al. in prep.).
The island of New Guinea is considered as one of the global centres of plant richness (Kreft & Jetz 2007; Cámara-
Leret et al. 2020). New Guinea is divided politically into western and eastern halves, corresponding to Indonesia and
Papua New Guinea, respectively. The island is at the junction between the Malesian, Melanesian and Australian floras
with very diverse geological and biological patterns, from snow-covered mountain ranges to extensive mangroves
along the coast. This makes the area potentially interesting for a wide range of biological and evolutionary studies; the
island, however, still remains poorly known botanically. In the western half, for example, recent expeditions led by
the Royal Botanic Gardens, Kew have collected extensively in the Bird’s Head Peninsula and the area adjacent to the
Lorentz World Heritage reserve (Johns et al. 2006), but other areas in West Papua and Papua Provinces have yet to have
any biological collections recorded (see Plantae species occurrences in GBIF.org 2019). In New Guinea, field surveys
usually focus on coastal and mountain areas, while the areas between are often neglected, especially the species-rich
lowland and montane forests (Heads 2001; Utteridge & de Kok 2007). This has resulted in a low collection density
across the island (see figures in Middleton et al. 2019), many parts of which are still waiting for intensive botanical
surveys.
SUMANON ET AL.
246 • Phytotaxa 505 (3) © 2021 Magnolia Press
During our taxonomic revision of New Guinean Maesa, based mainly on herbarium specimens, we came across
several morphologically distinct collections which differed from other collections determined with the same name.
For example, in the revision of Sleumer (1987), there are two widespread, and taxonomically problematic, species,
M. bismarckiana Mez (1922: 125) and M. haplobotrys F.Muell. (von Mueller 1866: 161) including several collections
that show variation in morphology and habitat when compared to other specimens and the types of these two names.
Most of specimens examined for the new species here were previously included in M. bismarckiana, M. haplobotrys,
M. rufovillosa Mez (1902: 38) or M. sayersii Sleumer (1987: 60).
Materials and methods
This study includes the areas of New Guinea, New Britain, New Ireland and Bougainville. Identification of the new
species was undertaken with the use of relevant literature, specifically Mez (1902), Sleumer (1987) and Utteridge
(2000, 2001, 2003, 2013, 2015). Morphological examination was based on herbarium specimens from A, AAU, BISH,
BO, CANB, E, GH, FU, K, L, M and NY. Some collections that we could not consult directly were accessed from
online platforms: JSTOR Global Plants (http://plants. jstor.org/ - coverage includes B, BM, BR, BRI, P etc. in addition
to A, K etc.) and Naturalis BioPortal (http://bioportal.naturalis.nl/ - coverage includes U and WAG in addition to L).
For morphological trait determination, the vegetative parts were measured from dry materials, while the reproductive
parts were measured from rehydrated materials; format of the descriptions follows Utteridge (2000, 2001, 2015) and
Sumanon et al. (2020), for example, Maesa species are either self-supporting trees or non-self-supporting scramblers
that are usually described as climbers and lianas, the persistent calyx and bracteoles allow merosity and bracteole
morphology to be described from fruit where flowers have not been seen. The terminology follows Beentje (2016),
additional leaf morphological terms follow Hickey (1979) and the Systematics Association Committee for Descriptive
Biological Terminology (1962). Colour indication was referred to drying colours following the colour charts in Beentje
(2016) or based on details given on the label. Examined specimens were geo-referenced based on coordinates from
labels when available or obtained using GeoNames (http://geonames.nga.mil/namesgaz) and refined with Google
Earth. Distribution and ecology were obtained from label data.
Statistical analyses were performed in RStudio (R version 3.6.3) for testing the correlation of elevation and
leaf length or leaf width of M. prolatifructa and M. sayersii measured from herbarium specimens (n = 15 for M.
prolatifructa and n = 13 for M. sayersii). The distribution of the data was tested using a Shapiro-Wilk normality test.
All datasets are normally distributed at a 95% confidence level, therefore, the Pearson correlation test was used to
determine correlation between elevation and leaf length or leaf width of these two Maesa species, and a Welch two
sample t-test was used to investigate the difference of means between leaf length and leaf width of M. prolatifructa and
M. sayersii.
Taxonomy
Maesa angustibracteolata Sumanon & Utteridge, sp. nov. (Fig. 1)
Recognised in the genus Maesa by the following combination of characters: the scrambling habit, lacking hairs but with scales throughout,
obovate leaves, simple to compound racemose inflorescences and pentamerous flowers with distinctive narrowly triangular
bracteoles;
Type:—PAPUA NEW GUINEA. Central Province: Western Section, Tributary of Laloki River, 2 miles E of Rouna, 9°25’S, 147°19’E,
elev. 1900 ft [c. 580 m], 11 September 1962, T.G. Hartley 10713 (holotype K!; isotypes CANB!, L image!).
Scrambler. Indumentum: all parts lacking hairs, scaly on leaf lamina surfaces, inflorescences and fruits, scales peltate,
up to 0.15 mm in diameter, pale ginger brown, ± sessile, circular with irregular margins. Branches drying reddish
brown (chestnut) with scattered lenticels. Leaves: lamina obovate, 5.8–11.2 cm long, 3.8–6.0 cm wide, sub-coriaceous,
drying dark brown above, reddish brown below, ad- and abaxial surfaces scaly; base obtuse to cuneate; margins entire;
apex rounded to obtuse, sometimes emarginate; midrib glabrous adaxially and abaxially (scales absent); secondary
veins 6 pairs, eucamptodromous, indumentum as lamina; petiole 1.7–2.5 cm long, glabrous. Staminate inflorescences
and flowers not seen. Pistillate inflorescences terminal, solitary, racemose, simple or compound with 2–3 branches,
SIX NEW SPECIES OF MAESA (PRIMULACEAE) Phytotaxa 505 (3) © 2021 Magnolia Press • 247
4–10 cm long in fruit, axis scaly. Pistillate flowers not seen, pentamerous (floral merosity determined from fruit
morphology), bracts narrow triangular. Fruits globose, 3.5–3.7 mm long, 3.2–3.6 mm diameter, scaly, reddish brown;
pedicels in fruit 2.3–2.9 mm long, densely scaly distally; bracteoles narrow triangular, 0.7–1.0 mm long, 0.2–0.3 mm
wide, apex acute, margins entire, scaly, remaining ±opposite each other at the base of the fruit; calyx lobes overlapping,
persistent.
FIGURE 1. Maesa angustibracteolata Sumanon & Utteridge. A habit, plant in fruit; B node with petiole and inflorescence base; C leaf
abaxial surface; D part of infructescence; E fruit apex; F LS of fruit; G scales on fruit surface; H scales on pedicel. All from Hartley 10713
(K). Scale bars: dashed bar = 0.5 mm, graduated single bar = 2 mm and 5 mm, double bar = 1 cm, graduated double bar = 5 cm. Illustration
by Andrew Brown.
SUMANON ET AL.
248 • Phytotaxa 505 (3) © 2021 Magnolia Press
Distribution and ecology:—The species is currently only known from Central Province in Papua New Guinea.
It was recorded as liana or climber in rainforest on slopes from c. 580 m to c. 1280 m elevation.
Etymology:—The epithet refers to the distinct, narrowly triangular bracteoles.
Additional material examined:—PAPUA NEW GUINEA. Central Province: Boridi [9°5’S, 147°38’E], elev. c.
4000 ft [c. 1220 m], 22 October 1935 (fr.), C.E. Carr 14704 (CANB!, K!, L image!); ibid., elev. c. 3500 ft [c. 1067 m],
22 October 1935 (fr.), C.E. Carr 14716 (CANB!, K!, L image!); ibid., elev. 4200 ft [c. 1280 m], 7 November 1935 (fr.),
C.E. Carr 14822 (CANB!, L image!, NY!).
Notes:—Maesa angustibracteolata is unique in the genus in having narrow triangular bracteoles and is thus
easily distinguished from all other species in the genus. The combination of characters including the scrambling habit,
obovate leaves, simple to compound racemose inflorescences with pentamerous flowers (the persistent calyx lobes
on the fruit allow inferences of floral merosity), and lacking hairs but being scaly in most parts, makes this species
distinctive.
From the key to the genus provided by Sleumer (1987), M. angustibracteolata would key out to M. haplobotrys
because Sleumer did not make use of plant habit in the key - several of his taxa are morphologically heterogenous
with regard to habit, something that is observable only during field studies, e.g., see the differences between the shrub
species M. ruficaulis S.Moore (1916: 102) and the scrambling (‘climbing’) species M. rufovillosa detailed in Utteridge
(2001: 680; 2013: 683). Maesa angustibracteolata is unlikely to be confused with M. haplobotrys, even though they
share the same floral merosity and indumentum, with the habit being especially diagnostic (M. angustibracteolata is a
scrambling species; M. haplobotrys is a shrub/tree species), together with the leaf morphology (M. angustibracteolata
with obovate leaves with rounded to obtuse or sometimes emarginate apices; M. haplobotrys with elliptic–obovate
leaves with acute apices), and inflorescence structure (M. angustibracteolata with mostly compound racemes with
2–3 branches, occasionally simple, solitary in the leaf axils; M. haplobotrys with 1–3 simple racemes from the same
axil).
Of the other scrambling Maesa species in New Guinea, M. angustibracteolata is most similar to M. loranthifolia
Mez (1922: 125), but differs from that species in the free bracteoles (bracteoles fused in M. loranthifolia), compound
racemose inflorescences with 2–3 branches (occasionally simple racemose) (simple racemose in M. loranthifolia),
obovate leaves with 6 pairs of secondary veins and a rounded to obtuse, or sometimes emarginate, apex (elliptic to
obovate leaves with usually 4 pairs of secondary veins and a broadly acute apex in M. loranthifolia).
The flowers were noted as being ‘dull brownish olive’ (fide Carr 14704) but no flowers were seen on the material
examined, only hypanthia/young fruit. All species of Maesa have white corollas and we assume that Carr was referring
to the infructescences and the developing fruits, rather than the flowers.
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
SIX NEW SPECIES OF MAESA (PRIMULACEAE) Phytotaxa 505 (3) © 2021 Magnolia Press • 249
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.
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.
SUMANON ET AL.
250 • Phytotaxa 505 (3) © 2021 Magnolia Press
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).
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, ginger-
brown, 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).
SIX NEW SPECIES OF MAESA (PRIMULACEAE) Phytotaxa 505 (3) © 2021 Magnolia Press • 251
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.
SUMANON ET AL.
252 • Phytotaxa 505 (3) © 2021 Magnolia Press
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.
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.
SIX NEW SPECIES OF MAESA (PRIMULACEAE) Phytotaxa 505 (3) © 2021 Magnolia Press • 253
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.
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254 • Phytotaxa 505 (3) © 2021 Magnolia Press
FIGURE 5. Maesa pusilliflora Sumanon & Utteridge. A habit (all leaves abaxial) with example of adaxial leaf surface to right; B node
with petiole and base of inflorescence; C abaxial surface of leaf; D part of inflorescence; E pistillate flower, hydrated; F corolla opened
flat; G LS of flower in E after removal of corolla; H fruit. A–G from Takeuchi 4645 (K), H from Takeuchi 4645 (BISH). Scale bars: single
bar = 1 mm, graduated single bar = 5 mm (D) and 2 mm (H), double bar = 1 cm, graduated double bar = 5 cm. Illustration by Andrew
Brown.
SIX NEW SPECIES OF MAESA (PRIMULACEAE) Phytotaxa 505 (3) © 2021 Magnolia Press • 255
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).
Maesa pusilliflora Sumanon & Utteridge, sp. nov. (Fig. 5)
Recognised in the genus Maesa by the combination of the following characters: obovate to oblanceolate leaves, entire leaf margins,
pentamerous flowers, non-overlapping triangular calyx lobes, long hypanthium (more than 0.6 mm long), simple racemes, solitary
or fasciculate with more than 15 flowers per inflorescence, and the flowers with non-overlapping triangular calyx lobes and the
hypanthium 0.7–1.00 mm long.
Type:—PAPUA NEW GUINEA. Morobe Province: near Ilauru, basin of the upper Bulolo River [7°7’S, 146°36’E], elev. 1005.4 m, 19
August 1989 (fl.), W. Takeuchi 4645 (holotype BISH!; isotypes A!, K!, L image!).
Small treelet. Indumentum: all parts lacking hairs, scaly on lamina surfaces, buds, inflorescences and fruits; scales
peltate, up to 0.04–0.10 mm in diameter, cream–ginger, ± sessile, circular with irregular margins. Branches drying
grey-brown with scattered lenticels, glabrous, scaly to densely scaly on young parts. Leaves: lamina obovate, 4.9–
7.0 cm long, 2.9–4.1 cm wide, sub-coriaceous, drying dark olive green above, tawny-brown below, adaxial surface
glabrous, scaly when young, abaxial surface glabrous; base cuneate; margins entire; apex obtuse or sometimes acute;
SUMANON ET AL.
256 • Phytotaxa 505 (3) © 2021 Magnolia Press
midrib drying reddish brown, glabrous both adaxially and abaxially; secondary veins 6–8 pairs, semicraspedodromous,
indumentum as lamina; petiole 0.9–1.1 cm long, glabrous. Staminate inflorescences and flowers not seen. Pistillate
inflorescences lateral (axillary), racemes, solitary or fasciculate with up to 3 inflorescences per axil, 4–5 cm long at
anthesis, c. 5.5 cm long in fruit, axis sparsely scaly; pedicels 1.5–3.0 mm long, scaly distally; bracts ovate to triangular,
0.5–0.7 mm long, scaly to densely scaly, margins entire, apex acute; bracteoles ±opposite, inserted at the base of short
elongated stalk of the hypanthium, shape as bracts, (0.45–) 0.6–0.7 (–0.9) mm long, 0.3–0.5 mm wide. Pistillate
flowers pentamerous, drying whitish cream; calyx lobes triangular, 0.44–0.56 mm long, 0.5–0.9 mm wide, glabrous,
margins entire to ciliate, apex acute; corolla tube c. 0.6 mm long, corolla lobes 0.44–0.7 mm long, 0.5–0.8 mm wide;
hypanthium 0.7–1.0 mm long, scaly; ovary c. 0.4 mm long, 0.7–0.94 mm diameter, style 0.36–0.40 mm long. Fruits
globose, 2.0–2.6 mm long, 2.1–2.8 mm diameter, sparsely scaly; pedicels in fruit c. 2 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 specimen collected from Morobe
Province, Papua New Guinea. The plant was found as a small treelet in burn-maintained rangeland with Cycas, Maotia,
and Mussaenda shrubbery.
Etymology:—The epithet is derived from the Latin word ‘pusilli’ and the word ‘flora’ to refer to its tiny flowers;
to be precise, whilst all species of the genus have small flowers, the corolla of this species is obviously smaller
comparative to the hypanthium size.
Notes:—Maesa pusilliflora may be distinguished by the combination of characters outlined in the diagnosis. It is
similar to M. beamanii, but it may be distinguished by floral merosity (pentamerous) and inflorescence structure (simple
racemose with more than 15 flowers). This species is also similar to M. oblanceolatifolia, another new species from
Milne Bay Province described in this paper; however, M. pusilliflora may be distinguished from M. oblanceolatifolia
by the non-overlapping triangular calyx lobes and longer hypanthium (more than 0.6 mm long).
Maesa prolatifructa Sumanon & Utteridge, sp. nov. (Fig. 6)
Recognised in the genus Maesa by the combination of the following characters: comparatively long petioles up to 4 cm long, lanceolate
leaves with a coriaceous lamina, and the leaves drying olive-green with a reddish brown abaxial midrib.
Type:—PAPUA NEW GUINEA. East New Britain District: Pomio Subdistrict, lower slopes of Mt Lululua, 5°43’S, 151°2’E, elev. 1250
m, 6 May 1973 (fr.), P.F. Stevens & Y. Lelean LAE 58298 (holotype K!; isotypes BISH!, CANB!, L image!, M!).
Tree or shrub to 18 m. Indumentum: all parts lacking hairs, scaly on lamina surfaces; scales peltate, up to 0.9 mm in
diameter, reddish brown or ginger brown with a central dark spot, ± sessile, circular. Branches drying dark reddish
brown with scattered lenticels, glabrous. Leaves: lamina lanceolate, 7.3–11.7 cm long, 2.4–4.2 cm wide, coriaceous,
adaxial surface glabrous, abaxial surface scaly, base attenuate or cuneate, margins entire and distinctly marginate on
drying (i.e. with the marginal tissue raised and distinct), apex acute; midrib glabrous, distinctly raised abaxially, drying
olive-green adaxially and reddish brown abaxially, secondary veins 5–8 pairs, craspedodromous; petiole 1.8–4.0 cm
long, glabrous. Staminate inflorescences and flowers not seen. Pistillate inflorescences lateral (axillary), racemes,
solitary or fasciculate with up to 3 inflorescences per axil, 2–3 cm long at anthesis, 3–7 cm long in fruit, axis densely
scaly; pedicels 1.2–1.7 mm long, densely scaly distally; bracts triangular, 1.2–1.5 mm long, scaly, margins entire to
ciliate, apex acute; bracteoles ±opposite, inserted at the base of the hypanthium, shape as bracts, 0.9–1.2 mm long,
0.75–0.90 mm wide. Pistillate flowers pentamerous; calyx lobes ovate, 0.75 mm long, 0.75–0.85 mm wide, glabrous,
margins entire, apex acute; corolla not seen; hypanthium 1.5–2 mm long, scaly to sparsely scaly; style not seen. Fruits
ellipsoid, prolate at the poles, reddish brown, 6.0–10.0 mm long, 4.0–5.7 mm diameter, scaly; pedicels in fruit 3.0–6.0
mm long; bracteoles remaining ±opposite each other at the base of the fruit; calyx lobes overlapping, persistent.
Distribution and ecology:—The species is found at an elevation of 1250–1500 m in montane forests of New
Ireland and New Britain in Papua New Guinea.
Etymology:—The specific epithet refers to the prolate, ellipsoid fruit of this new species, a feature found in this
taxon and in M. sayersii Sleumer.
Additional material examined:—PAPUA NEW GUINEA. East New Britain District: Pomio Subdistrict, Mt
Sule, about 25 miles NNE of Fulleborn Harbour, 5°50’S, 150°50’E, elev. 1500 m, 7 May 1973 (fr.), J.R. Croft & P.
Katik NGF 41940 (distributed partly as 14940) (BISH!, CANB!, E!, K!, L image!); New Ireland Province: Namatanai
Sub-province, Hans Meyer Range, on steep ridge near camp, c. 8 km W.N.W. of Taron on east coast, 4°24’S, 152°58’E,
elev. 1350 m, 23 October 1975 (fl. & fr.), M.J.S. Sands 2329 (K!, L image!).
SIX NEW SPECIES OF MAESA (PRIMULACEAE) Phytotaxa 505 (3) © 2021 Magnolia Press • 257
FIGURE 6. Maesa prolatifructa Sumanon & Utteridge. A habit; B node with petiole and base of inflorescence; C abaxial surface of leaf;
D terminal portion of inflorescence; E hydrated flowers, one large calyx lobe removed, young ‘dome’ of corolla visible; F flower to show
young corolla ‘dome’; G corolla from below showing insertion point of young stamen (5-merous flower); H corolla opened flat; I fruit,
dry; J fruit after soaking; K detail of scales from fruit surface. A, C, I–K from Stevens & Lelean. LAE 58298 (K); B, Croft & Katik NGF
41940 (K); D–H Sands 2329 (K). Scale bars: single bar = 1 mm, graduated single bar = 5 mm, double bar = 1 cm, graduated double bar =
5 cm. Illustration by Andrew Brown.
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258 • Phytotaxa 505 (3) © 2021 Magnolia Press
FIGURE 7. Leaf comparison between M. sayersii and M. prolatifructa. A Leaves of M. sayersii; B Leaves of M. prolatifructa; C a boxplot
showing leaf length of each species; D a boxplot showing leaf width of each species. Scale bar = 5 cm. Illustration by Pirada Sumanon.
Notes:—Maesa prolatifructa is unique in the genus in having lanceolate leaves with a reddish-brown raised
midrib on the abaxial side. It is unlikely to be confused with any other species in New Guinea and can be easily
distinguished from its most similar species, M. sayersii, by leaf characters, viz: coriaceous texture (chartaceous to
sub-coriaceous in M. sayersii), shape (lanceolate vs elliptic in M. sayersii), length and width ratio (2.1–4.3 vs 1.7–3.2
in M. sayersii), size (7.3–11.7 cm long by 2.4–4.2 cm wide vs 11.5–28.8 cm long by 4.0–15.5 cm wide in M. sayersii,
Fig. 7), and venation (5–8 secondary vein pairs per leaf vs 6–10 in M. sayersii). The distribution of M. prolatifructa, as
currently known, is limited to East New Britain and New Ireland Provinces of Papua New Guinea, while M. sayersii
is distributed in West New Britain, New Hanover, New Ireland and Manus Island. Maesa prolatifructa is also found at
higher elevations around 1250–1500 m, while M. sayersii is at lower elevations around 30–900 m.
SIX NEW SPECIES OF MAESA (PRIMULACEAE) Phytotaxa 505 (3) © 2021 Magnolia Press • 259
Several previous studies have pointed out the effect of elevation gradients on morphological and anatomical
variation within species. Most studies showed a decrease in leaf size and an increase in leaf thickness of plants growing
at high elevations as a modification to the environment (e.g., Scheepens et al. 2010, Bresson et al. 2011), posing the
question: is this new species an altitudinal variant of M. sayersii? To test this, a correlation test was performed to see if
there is any correlation between elevation and leaf length or leaf width. Although the sample size was small, there is no
significant correlation between elevation and leaf size in both species, and mean length and width of both species are
significantly different (Fig. 7 and Table 1); this evidence further supports recognition of M.prolatifructa as a distinct
species. Further studies using population genetic methods could clarify and confirm the taxonomic status of these two
species.
TABLE 1. Statistical values for dataset measured from leaves of M. prolatifructa and M. sayersii.
M. prolatifructa
(n = 15)
M. sayersii
(n = 13) p-value
Mean (± SD)
Leaf length (cm)
Leaf width (cm)
9.787 ± 1.338
3.067 ± 0.497
18.138 ± 5.168
8.254 ± 3.796
P<.001
P<.001
Correlation coefficient
Elevation~Length
Elevation~Width
-0.3247 (P=.24)
-0.1037 (P=.71)
-0.0499 (P=.87)
-0.1205 (P=.7)
Acknowledgements
We would like to thank A, BISH, BO and L herbaria for providing specimens in the study, Dr Andrew Brown for the
beautiful illustrations, a GSST grant from Aarhus University for promoting PhD students staying and conducting
research aboard, and the Royal Thai Government Scholarship for financial support throughout PhD study of the first
author. We are very appreciative of the comments from the reviewers which have greatly improved the paper. We
would also like to thank the Centre for Australian National Biodiversity Research and CSIRO’s National Research
Collections Australia for facilitating TU’s visit to the Australian National Herbarium (CANB) to work on the
Myrsinoideae collections from New Guinea.
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