Thulin et al. 2012

TAXON 61 (2) • April 2012: 308–323
Additional collection studied. – MADAGASCAR: Mahajanga,
Amboanio near Mahajanga, Feb. 1901, Perrier de la
Bâthie 1227 (K, P).
Taxonomic remarks. – Arboa madagascariensis is close to
A. berneriana, but seems distinctive by its larger leaves, usually
well over 5 cm long, larger sepals (18–28 versus 8–15 mm
long) without marginal glands, and larger anthers (5–10 mm
versus 2.5–5 mm long).
4. Arboa antsingyae (Arbo) Thulin & Razafim., comb. nov. ≡
Erblichia antsingyae Arbo in Adansonia, sér. 2, 18: 476.
1979 – Type: Madagascar, “forêt de l’Antsingy, près de la
clairière d’Ambodiriana (piste Antsalova–Tsiandro), 15
Dec. 1952, Capuron 6832-SF (P!, lectotype, P00077555,
designated here; K!, P!, S!, TEF, isolectotypes).
Piriqueta antsingyae Capuron in Adansonia, sér. 2, 3: 133
(1963) was not validly published as three collections with different
collectors and numbers were cited (Leandri 2173, Capuron
6832-SF, Razafindrakoto 4703-RN). The three collections
were made at the same occasion and Capuron therefore regarded
them all as parts of one single collection. However, this
view is not in accordance with the ICBN, Art. 8 (McNeill & al.,
2006). Furthermore, only two of the collections were made 15
Dec. 1952, Razafindrakoto 4703-RN being dated 14 Dec. 1952.
Arbo (1979) treated this species as Erblichia antsingyae,
cited a single collection (Capuron 6832-SF) as (lecto)type, and
at the same time provided a full and direct reference to the Latin
diagnosis and description of Piriqueta antsingyae. Her name
therefore fulfills the requirements for valid publication of the
ICBN, Art. 45.1 (McNeill & al., 2006), although she intended
it as a new combination.
The collection Capuron 6832-SF in P consists of four duplicates.
The best sheet, P00077555, is here designated as lectotype,
whereas P00077556, P00077557, plus one unnumbered
sheet, are treated as isolectotypes.
Tree, 8–10 m tall; branchlets glabrous. Leaves elliptic,
13–20 × 5–10 cm, glabrous, shortly acuminate or rarely obtuse
at the apex, narrowing below into a 10–20 mm long petiolelike
base with a pair of projecting ca. 3 mm wide cup-shaped
glands in upper part, margin subentire to denticulate-crenulate,
the teeth obtuse and minutely gland-tipped; lateral veins 13–20
pairs. Flower buds acute; pedicel 60–105 mm long, glabrous,
articulated 15–28 mm from the tip; bracteoles ca. 1 mm long.
Sepals 30 × 7–8 mm, glabrous, acute. Petals 35–45 × 20–30 mm,
orange-red, acute to shortly acuminate; corona ca. 3 mm high,
inserted at base of petals and sepals, with 5 ± marked lobes opposite
the petals. Stamens inserted at base of sepals; filaments
17–20 mm long; anthers ca. 13 mm long, curved, apiculate.
Ovary 4–5 mm long, sessile; styles 20–25 mm long, widely
divergent at the base, penicillate at the tips. Capsule ovoid,
25–30 × 20 mm, scars of floral parts forming a narrow band
below the fruit. Seeds (unripe) 4–5 mm long, very finely pitted
only; aril unilateral, lacerate, up to about as long as the seed.
Distribution and habitat. – Arboa antsingyae is known
only from the type locality in the Bemaraha Massif in western
Madagascar (Fig. 7D), where it grows in dry deciduous forest
on limestone at 100–150 m above sea level. All three collections
Thulin & al. • Phylogeny of the Turneraceae clade
were made on the same occasion, in July 1952, and perhaps
even from the same tree. The Bemaraha Massif (“Tsingy de
Bemaraha”) is still botanically little known and further localities
for this remarkable species may be anticipated.
Additional collection studied. – MADAGASCAR: Antsingy,
near Ambodiriana (Antsalova –Tsiandro road), 15 Jul.
1952, Leandri 2173 (B, G, P) & Razafindrakoto 4703-RN (P,
TAN).
Taxonomic remarks. – Arboa antsingyae is the only species
in the genus that grows to a medium-sized tree. It also
differs markedly from all the other species by its large leaves
(13–20 cm long) with a pair of projecting and about 3 mm
wide, cup-shaped glands in the upper part of the petiole-like
leaf base. Also, the flowers in A. antsingyae are larger than in
any of the other species.
ACKNOWLEDGEMENTs
We are indebted to Margaret Tebbs for the drawings, to Anders
Larsson for the distribution maps, and to the curators of BM, G, K,
MEXU, MO, P, S, TAN, TCD and UPS for putting herbarium material
and/or images at our disposal. We thank DGF (Direction Générale des
Forêts) and MNP (Madagascar National Parks) in Madagascar for issuing
collecting permits for MT and SGR, Missouri Botanical Program,
Madagascar, for logistical support, and Lalao Andriamahefarivo for
arranging collecting permits for MT and SGR. Field work on Madagascar
by MT was supported by the Swedish Research Council and
Hanta Razafindraibe is thanked for excellent company in the field.
Luis Poveda is thanked for assistance in the field in Costa Rica, Maria
Arbo for providing material, and Pieter Pelser and two anonymous
reviewers for suggesting improvements to the manuscript. A portion of
this work was funded by a Natural Sciences and Engineering Research
Council grant to JSS.
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