Schefflera pubicarpa Fiaschi & G. M. Plunkett, 2016

Fiaschi, Pedro & Plunkett, Gregory M., 2016, Two new species of the Didymopanax clade of Schefflera (Araliaceae) from the Brazilian Amazon, Phytotaxa 245 (2), pp. 153-160 : 155-157

Schefflera pubicarpa Fiaschi & G. M. Plunkett , sp. nov.

Type:— BRAZIL. Amazonas: rodovia de Manaus (AM) a Porto Velho (RO), trecho entre os rios Castanho e Tupana, na altura do km 158. Hotel Tupana . 04°04’26” S, 60°40’11” W, 25 m, 18 July 2007 (fr), P. Fiaschi 3187 [holotype SPF-194357 (fr.)! ; isotypes INPA!, K!, MO!, NY!, RB!, SPF-194357 (st.)!, SPF-194357 (fr.)! ]. Figures 1A–K , 2A–D , 4 .

This new species differs from Schefflera morototoni ( Aublet 1775: 949) Maguire, Steyermark & Frodin (1984: 51) by the larger (12–13 × 15–16 mm vs. 4–6.5 × 7.5–11 mm), pubescent (vs. glabrescent) fruits, and the inflorescences, which lack tertiary branches (vs. tertiary branches usually present); from Schefflera tamatamaensis Maguire, Steyermark & Frodin (1984: 55) , the new species differs by the large tree habit (vs. treelet to about 6 m tall), leaves with 8 to 10 (vs. 4 to 7) leaflets, the flowers with trichomes along the styles (vs. glabrous styles), and the obloid or broadly depressed obovoid (vs. broadly depressed ovoid) drupes with laterally flattened and smooth (vs. swollen and irregularly sculptured) pyrenes.

Trees 15–25 m; branchlets 2.8–3.5 cm diam., striate longitudinally, light brown sericeous. Leaves palmately compound, clustered at branchlet apices, internodes to c. 1 cm long; stipules c. 2 cm long, adaxial surface glabrous, abaxial surface light brown sericeous, apex bifid, lobes c. 2 mm long; petiole 21.5–55 cm long, 2.5–5 mm diam., cylindrical, slightly striate longitudinally, glabrescent; leaflets simple, 8 to 10, grouped in one terminal whorl, held horizontally; blade plane to slightly conduplicate, chartaceous to subcoriaceous, adaxial surface glabrescent, abaxial surface light brown to grayish sericeous when mature; median leaflet with petiolules 4–8.5 cm long, unarticulated, slightly compressed laterally, slightly canaliculate adaxially; blade 14.5–26.5 × 3.8–8 cm, narrowly elliptic or oblong to lanceolate, base rounded, symmetrical to slightly asymmetrical, margin entire, revolute, sometimes slightly undulate, apex acuminate to caudate, tip mucronulate; basal leaflets with petiolules 1.8–3.7 cm long, blade 10–20 × 2.5–6.5 cm, asymmetrical, otherwise similar to the median leaflet; venation brochidodromous; primary vein prominent on both surfaces, more conspicuously so abaxially; secondary veins 9 to 12, prominent abaxially, impressed adaxially; intersecondary veins sometimes present; higher orders of venation inconspicuous, sometimes conspicuous adaxially. Inflorescence terminal, initially erect, branches becoming patent when fruiting, light brown sericeous; the peduncle 0.5–1.5 cm long, the remaining portion of the axis 5–8.5 cm long; primary branches 3 to 40, 2 to 6 of which are terminal, 8.7–36 cm long, with bracts 4–6 mm long, each branch bearing one terminal hermaphroditic umbel, or 22 to 75 racemiform secondary branches, each branch with 4–6 terminal branches, 9–28 mm long, with bracts 2–3 mm long; tertiary branches lacking; ultimate inflorescence units umbellules, number of flowers unknown; floral bracts c. 1 mm long. Perfect flowers with pedicels 2–3 mm long; hypanthium light brown sericeous, calyx rim with 5 acuminate teeth; petals 5, yellowish green, 3.7–3.8 × 1.3–1.8 mm, narrowly ovate to ovate, sericeous abaxially, apex acute or acuminate; filaments 0.8–1 mm long; anthers c. 1.8 × 1–1.1 mm, oblong, apex rounded, thecae free above the insertion of the connective; ovary 1–1.5 mm long, carpels 2(–3); disc pubescent; styles 2(–3), free, c. 1.2 mm long, pubescent, recurved in fruit; staminate flowers not seen. Drupes 12–13 × 15–16 mm, obloid or broadly depressed obovoid, compressed laterally or rarely 3-costate when dry, pubescent; pedicel 4–6 mm long; pyrenes 2(–3), 10.5–12.5 × 6.5– 7.5 mm, laterally compressed, semi-depressed obovate in outline, transversely linear, cartilaginous.

Distribution and ecology:— Schefflera pubicarpa grows in central Amazonian terra firme forests on sandy to clayey soils. The new taxon is known only from the type locality and vicinities, between the Castanho and Tupana rivers, on the road from Manaus (Amazonas state) to Porto Velho (Rondônia state), where it is a rather common species ( Fig. 4 ).

IUCN Red List category: —Due to the very incomplete knowledge of the distribution of plant taxa in the Amazon Forest, especially from areas south of the Amazonas river ( Hopkins 2007), we prefer to treat this species as data deficient (DD) for conservation purposes, following IUCN (2012).

Phenology:— This species has been collected with fruits (and a few late flowers) in July. However, fully flowering materials have not been collected so far. The flowers analyzed here were pickled from the type collection and are deposited among the spirit collections at SPF herbarium.

Discussion:— Schefflera pubicarpa resembles S. tamatamaensis , from which it can be distinguished by the habit as large trees (vs. unbranched treelets to 6 m tall in S. tamatamaensis ), leaves with eight to 10 (vs. four to seven) leaflets, inflorescences with ascending (vs. reflexed) secondary branches, flowers with trichomes along the styles (vs. glabrous styles), and the obloid or broadly depressed obovoid (vs. broadly depressed ovoid) drupes with laterally flattened and smooth (vs. swollen and irregularly sculptured) pyrenes.

One of the specimens included in Schefflera pubicarpa ( Silva et al. 852) was collected about 100 km north of the type locality. In this specimen, the leaflets have smaller (c. 15 × 4 cm, vs. 21–26.5 × 7–8 cm) and narrowly elliptic (vs. lanceolate) blades, and the fruits are oblongoid, ca. 13 × 13 mm (vs. broadly depressed obovoid, 12–13 × 15–16 mm). The inflorescences may have only three primary branches, each bearing 19 to 20 secondary branches (the INPA-36943 duplicate), or up to 16 primary branches, each bearing one terminal hermaphroditic umbel and five or six lateral sterile bracts (the MO-3499822 duplicate). These features may be sufficiently distinctive to recognize this collection as another new species, but we believe these differences may prove to represent intraspecific variation as more collections of S. pubicarpa become available.

Additionally, several samples from the Amazonian white-sand forests of northeastern Peru (Iquitos region), southeastern Colombia, and eastern Ecuador also appear to belong under Schefflera pubicarpa . However, most of these specimens are either fragmentary or represent sterile voucher materials from ecological studies. These samples have leaves with very long petioles (70–75 cm long), bearing 11–12 large leaflets (the median leaflet being 27–31 × 10–16 cm long), with the leaflet blade chartaceous to subcoriaceous and persistently light brown to grayish-sericeous abaxially, with a caudate apex, and an obtuse to truncate base. The inflorescence primary branches are about 50 cm long, and the umbels are terminal or on short (1–2.5 cm long), racemosely arranged secondary branches. The flowers have a pubescent disc and the fruits are reminiscent of those from S. pubicarpa . At this moment, we consider it premature to place these materials as paratypes of this new species before additional collections become available, especially considering the geographic distance separating these collections from the main distribution of S. pubicarpa (more than 1000 km away) (see Fig. 4 , as Schefflera sp. aff. pubicarpa ). So far, there are no data that currently supports a continuous distribution for S. pubicarpa over the western Amazon, and, if confirmed, this apparent disjunction could be explained by the dearth of botanical knowledge in intermediate areas (e.g., the Purus–Juruá interfluve, Hopkins 2007).

Paratypes:— BRAZIL. Amazonas: Estrada Manaus–Porto Velho, trecho entre os rios Castanho e Tupana , 20 July 1972 (fr), M. F. Silva e pessoal da Botânica 964 (INPA-37055) ; Estrada Manaus–Porto Velho, km 50, estrada Castanho–Tupana , 18 July 1972 (fr), M. F. Silva e pessoal da Botânica 852 (INPA-36943, MO-3499822) .

Figures

FIGURE 1. A−K. Schefflera pubicarpa. A. Fruiting branch. B. Stipule, lateral view. C. Basal leaflet, abaxial view. D. Median leaflet, abaxial view. E. Bisexual flower, one petal and stamens removed, lateral view. F. Bisexual flower, stamens removed, lateral view. G. Petal, lateral view. H. Stamen, adaxial view. Stamen, abaxial view. J. Terminal inflorescence unit. K. Fruit, lateral view. L−O. Schefflera prancei. L. Fruiting branch. M. Median leaflet from outer whorl. N. Median leaflet from inner whorl. O. Fruit, lateral view. [Drawings by P. Fiaschi].

FIGURE 2. Schefflera pubicarpa and the similar species S. morototoni. A−D. Schefflera pubicarpa. A. Fruiting branch. B. Detail of leaf bases and terminal infructescence. C. Detail of fruiting branch. D. Fruits. E−G. Schefflera morototoni. E. Habit. F. Detail of leaf bases and terminal young infructescence. G. Detail of primary inflorescence branch. [Photos by P. Fiaschi].

FIGURE 4. Geographic distribution of Schefflera prancei, S. pubicarpa, and similar species from the Amazonian lowlands (see text for morphological comparison between species).