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Research Article
The Araceae of Sumatra I: A new species of Alocasia from Aceh, Indonesia
expand article infoNi Putu Sri Asih‡, Ina Erlinawati‡, Yuzammi‡, Julisasi Tri Hadiah‡
‡ Research Center for Biosystematics and Evolution, National Research and Innovation Agency, Cibinong, Indonesia

Corresponding author: Ni Putu Sri Asih ( nieeputse@gmail.com )

Academic editor: Duilio Iamonico
© 2024 Ni Putu Sri Asih, Ina Erlinawati, Yuzammi, Julisasi Tri Hadiah.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation: Asih NPS, Erlinawati I, Yuzammi, Hadiah JT (2024) The Araceae of Sumatra I: A new species of Alocasia from Aceh, Indonesia. PhytoKeys 249: 223-229. https://doi.org/10.3897/phytokeys.249.133737
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Abstract

Alocasia roseus is described as a new species from Aceh Besar Regency, Sumatra (Indonesia). The plants found produce stunning inflorescence, leading to over-collecting in the wild. The new species is morphologically similar to A. flemingiana but differs by its greyish green adaxial leaves and pale reddish to greenish purple or pale brownish green abaxial leaves, lacking interprimary veins and sinus not naked, thecae overtopped by synconnective, and a pale pink appendix. The new species is also similar to A. arifolia, from which it differs by the glabrous and pale dull green petiole, the colour of abaxial and adaxial leaves, not forming interprimary vein, sinus not naked, and pale pink appendix. The new species is compared with other similar Indonesian taxa and an identification key to the species of Alocasia in Sumatra, supplemented with photographs, are provided.

Key words

Aceh Besar, Alocasia roseus, Indonesian flora, new taxon

Introduction

The genus Alocasia (Schott) G.Don (Araceae Juss.) consists of 100 species (Promprom et al. 2024) but current research suggest that there may be an additional 41 undescribed species (Boyce and Croat 2023). This genus is distributed in tropical and subtropical Asia ranging from the Malesian region toward Oceania and to mainland Australia (Nauheimer et al. 2012; POWO 2024; Promprom et al. 2024). Borneo is considered to bear the richest diversity and endemism of Alocasia (Hay 1998). However, the diversity and distribution of Alocasia are poorly understood in the Indonesian archipelago, with about 27 known species (Asih and Lestari 2022; Asih et al. 2022). Prior to this study, there were seven species of Alocasia recognised in Sumatra (Hay 1998; Erlinawati 2011; Kurniawan et al. 2013; POWO 2024).

Our knowledge of Alocasia in the Sumatra is currently inadequate and, consequently, further exploration and collection of plants is necessary. The under-collection of Alocasia from Sumatra is reflected in the few specimens held at Herbarium Bogoriense (BO) and other international herbaria. Furthermore, the last taxonomic revision of Alocasia was done over twenty-five years ago (Hay 1998) who recognised six Sumatran Alocasia taxa (Alocasia alba Schott, A. arifolia Hallier f., A. inornata Hallier f., A. longiloba Miq., A. kerinciensis A.Hay, and A. puber (Hassk.) Schott). Alocasia macrorrhizos (L.) G.Don is listed as an introduced species to Sumatra (POWO 2024).

Based on Praetorius s.n. (L.1415481), A. puber was thought to occur in Sumatra (Hay 1998), but is here now regarded as A. alba. A. puber is only known from Jawa. Erlinawati (2011) recorded A. flemingiana Yuzammi & A.Hay from Siberut Island (a small island off the western coast of Sumatra), a species that was previously only known from Jawa (Hay 1998). A recent study by Mustaqim and Setiawan (2019) provided an update on the distribution of A. alba upon finding the species in Tanggamus Regency, Lampung Province, Sumatra.

Since Alocasia has been known as one of the most popular ornamental plants, sought for and traded by enthusiasts and the general public, many species are collected directly from the forest and traded illegally. One of the species, traded by people from Aceh, is here considered as the new species Alocasia roseus. The work is part of an ongoing study of Araceae family in Sumatra region.

Material and methods

Plants were collected from the forest near Kueh Kemukiman Keude Bieng, Kueh Village, Aceh Besar Regency, Aceh Province, Sumatra (Fig. 1), by people who live nearby the forest. It was then cultivated at a nursery, from which we obtained some plants. Pertinent literature was considered for the taxonomic investigation (e.g. Hallier 1901; Hay 1998) Photographs of herbarium specimens held at L were included in this study.

Figure 1. 

Distribution map of Alocasia roseus Asih & Yuzammi, sp. nov. showing the location where the new species was discovered in Aceh Besar (red shading). Inserts: overview of Indonesian archipelago (right) and Aceh Province (left). Map by Rani Yudarwati.

Taxonomic treatment

Alocasia roseus Asih & Yuzammi, sp. nov.

urn:lsid:ipni.org:names:77346080-1
Fig. 2, Table 1

Type

(prepared from a cultivated plant in a private nursery). Indonesia • Aceh, Aceh Besar, Lhoknga, Desa Kueh, Kueh Kemukiman Keude Bieng, PSA 395 (holotype BO! [dried specimens and inflorescences in spirit]; isotype ANDA!) (Fig. 2).

Figure 2. 

Alocasia roseus: A habit B adaxial leaf C abaxial leaf D petiole E inflorescence with spathe F inflorescence with the spathe removed showing the zonation of reproductive organs G female zone (♀) H sterile interstice zone (s) I male zone (♂) J appendix (a). (Photographed and edited by Ni Putu Sri Asih and Julisasi Tri Hadiah).

Diagnosis

(Table 1). Alocasia roseus is morphologically similar to A. flemingiana and A. arifolia from which it differs by having greyish green adaxial leaves and pale reddish to greenish purple or pale brownish green abaxial leaves, interprimary vein absent, sinus not naked, and pale pink appendix (vs. mid-green to dark green adaxial and green-yellowish/paler abaxial leaves, forming poorly to conspicuous interprimary vein, sinus naked up to 3 cm, and cream/pale apricot appendix).

Table 1.
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Comparison of important diagnostic characters of Alocasia roseus, A. flemingiana and A. arifolia.

Diagnostic characters Alocasia roseus Alocasia flemingiana Alocasia arifolia
Blade leathery, greyish green adaxially, reddish to greenish purple to pale brown greenish abaxially membranous, mid-green adaxially, yellowish green abaxially membranous to thinly coriaceous, somewhat glossy, dark/mid-green adaxially, paler abaxially
Venation not forming interprimary collective veins interprimary veins absent or poorly differentiated forming undulating to zig-zag interprimary collective veins
Glands inconspicuous axillary glands distinct small flat glands inconspicuous axillary glands
Sinus not naked naked for up to 1 cm naked in the sinus for up to 3 cm
Constriction at base of male zone or to half way along male zone at top of sterile zone of spadix at sterile interstice
Spadix shorter than spathe, shortly stipitate for 2–4 mm long somewhat shorter to almost as long as spathe, stipitate for c. 5 mm almost as long as spathe, shortly stipitate, c. 3 mm long
Thecae overtopped by synconnective, thecae opening by apical pores somewhat displaced to overtopped by synconnective, thecae opening through apical slits overtopped by synconnective, thecae opening by apical pores
Appendix pale pink, gradually tapering to a blunt point, faintly irregularly channeled Cream-coloured appendix, tapering pale apricot-coloured, somewhat constricted at base, slightly narrower than male zone, tapering toward a point

Description

Small herb c. 55 cm tall; rhizome erect; leaves several together; petiole 34–38 cm long, pale dull green, glabrous, faintly mottled greenish, sheathing in the lower about 1/3 of its length, pale dull green; blades leathery, sagittate, greyish green adaxially, reddish to greenish purple to pale brown greenish abaxially, margin entire; anterior lobe 12.8–14.4 cm long, 9.7–11.6 cm wide, the widest is base of anterior lobe, tip acuminate, 7 mm long; anterior costa with 4–5 primary lateral veins on each side, proximal ones diverging at 76–96° on each side then running to submarginal vein, distal primary veins diverging at 40–45° on each side, primary vein prominent adaxially then forward to marginal becoming flush to lamina, prominent abaxially, with inconspicuous axillary glands, secondary and tertiary venation flush to lamina adaxially, rather prominent and conspicuous abaxially then running to conspicuous submarginal vein inserted c. 1.5 mm from margin, interprimary collective veins absent; posterior costae diverging at 60–80°, not naked in the sinus; posterior lobes acute, 6–7.2 cm long; inflorescences soliter or in pair, subtended by green cataphylls and then dried at flower anthesis; peduncle to c. 14.6 cm long, resembling petioles in colour and faintly mottled; spathe c. 9.7 cm long; lower spathe ovoid, yellowish green, c. 2.3 cm long, c. 1.8 cm diam; limb lanceolate, yellow to greenish, erect then tilted 45° after 3 days, separated from the lower spathe by a constriction at the base of male flowers or at top sterile interstice (to the midpoint of the male zone); spadix shorter than the spathe, c. 7 cm long, shortly stipitate, 2–4 mm, whitish-green, cylindric; female zone cylindric, 0.9–1 cm long, 0.9 cm wide; ovaries subglobose, green, stigma raised on a style 0.5–1 mm, conspicuously, (2–)3–4-lobed, pale yellow; sterile interstice cream-coloured, not attenuate, 0.4–0.5 cm long, narrower than male zone, with 4–5 whorls of rhomboid synandrodia; male zone cylindric, cream-coloured, 1.1–1.2 cm long; synandria rhombohexagonal to somewhat irregular, with the synconnective overtopped the thecae; thecae opening by apical pores; appendix pale pink, gradually tapering to a blunt point, faintly irregularly channeled, c. 3.5–4.2 cm long, slightly wider than the male zone; fruit unknown.

Distribution and habitat

The species is only known from Aceh Besar, Sumatra Island. It grows on the hillside of the forest, in shade and humid areas.

Etymology

The specific epithet, roseus, is based on the pale pink appendix of the staminodes found in this new species. This color of the appendix is rarely found in the genus.

Conservation status

Alocasia roseus is known only from a single locality in the forest near Kueh Kemukiman Keude Bieng, Kueh Village, Aceh Besar Regency, Aceh Province, Indonesia. Since further populations could occur, we prefer to assess these species as Data Deficient (DD) according to the IUCN Red List criteria (2022).

Notes

Alocasia roseus belongs to the informal group “Macrorrhizos” (sensu Hay 1998) in view of the following showed characteristics: inflorescences in pairs, the spathe constriction aligning with the sterile interstice of the spadix, and the synconnective overtopping the thecae. This species is the second, besides A. balgooyi, in the Macrorrhizos group with no naked sinus in their posterior lobe. Alocasia roseus also has an appendix color that differs from other species in the Macrorrhizos group. Pink being a rare colour of appendix that is found only in A. melo and A. princeps (Hay 1998).

Key of Alocasia Species in Sumatra

1 Leaf blades shallowly to completely peltate in mature plant 2
– Leaf blades not peltate in mature plant 3
2 Peltate leaf with posterior lobes almost fully fused; appendix white Alocasia kerinciensis A. Hay
– Peltate leaf with posterior lobes never almost fully fused; appendix very pale orange to bright yellow Alocasia longiloba Miq.
3 Robust to massive plant 4
– Medium to small plant 6
4 Interprimary collective vein well-defined Alocasia alba Schott
– Interprimary collective vein poorly defined 5
5 Inflorescences paired among lead base; peduncle exceeding length of cataphylls at anthesis; petiole glabrous Alocasia macrorrhizos (L.) G.Don
– Inflorescences many, clustered together; peduncle short, mostly hidden with leaf sheath and cataphylls; petiole glabrous or minutely pubescent Alocasia inornata Haillier f.
6 Intermarginal vein not formed; petiole puberulent or glabrous Alocasia arifolia Hallier f.
– Intermarginal vein conspicuous; petiole glabrous 7
7 Abaxial leaf reddish to greenish purple to pale brown, with greenish tinge; appendix pale pink Alocasia roseus Asih & Yuzammi
– Abaxial leaf yellowish green; appendix cream-colored Alocasia flemingiana Yuzammi & A.Hay

Acknowledgements

The authors extend our gratitude to the anonymous reviewers for providing constructive comments on the manuscript. We express our gratitude to Hendrasyah from Nurul Nursery, Aceh Tamiang for providing the plants of A. roseus used in our study. We also are deeply appreciative to Rani Yudarwati, former lecturer at the IPB University, Indonesia for providing the distribution map of this new species. We thank Barry J Conn, The University of Sydney, who edited the English expressions and grammar, and provided comments on the manuscript.

Additional information

Conflict of interest

The authors have declared that no competing interests exist.

Ethical statement

No ethical statement was reported.

Funding

No funding was reported.

Author contributions

NPSA: plant identification, description, writing-first draft. Y: description, writing-review and editing. IE: writing-review and editing. JTH: critical review and editing.

Author ORCIDs

Ni Putu Sri Asih https://orcid.org/0000-0002-4161-9235

Ina Erlinawati https://orcid.org/0000-0002-4621-4456

Yuzammi https://orcid.org/0000-0002-9637-9048

Julisasi Tri Hadiah https://orcid.org/0000-0002-5478-8118

Data availability

All of the data that support the findings of this study are available in the main text.

References

  • Asih NPS, Erlinawati I, Priyadi A (2022) Reconstructing phylogenies of Alocasia spp. (Araceae) distributed in Indonesia for conservation prioritization. Journal of Tropical Life Science 12(3): 317–323. https://doi.org/10.11594/jtls.12.03.04
  • Mustaqim WA, Setiawan E (2019) Alocasia alba (Araceae) in Southern Sumatra: Further distribution recorded. Aroideana 42: 18–22.
  • Nauheimer L, Boyce PC, Renner SS (2012) Giant taro and its relatives: A phylogeny of the large genus Alocasia (Araceae) sheds light on Miocene floristic exchange in the Malesian region. Molecular Phylogenetics and Evolution 63(1): 43–51. https://doi.org/10.1016/j.ympev.2011.12.011
  • Promprom W, Munglue P, Chatan W (2024) Alocasia sakonakhonensis (Araceae), a new species from northeastern Thailand. Ecology and Evolution 14(5): e11462. [7 pp] https://doi.org/10.1002/ece3.11462
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