Calamus retroflexus J.Dransf. & W.J.Baker, 2014

Baker, William J. & Dransfield, John, 2014, New rattans from New Guinea (Calamus, Arecaceae), Phytotaxa 163 (4), pp. 181-215 : 203-205

publication ID 10.11646/phytotaxa.163.4.1

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scientific name

Calamus retroflexus J.Dransf. & W.J.Baker


10. Calamus retroflexus J.Dransf. & W.J.Baker , sp. nov. Type:— INDONESIA. Papua Province: Timika, upstream from end of road to Kali Kopi river from mile 38, 95 m, 4°25'43"S, 136°57'7"E, 24 February 1998, Dransfield et al. JD 7723 (holotype K!, isotypes BH!, BO!, L!, MAN!) GoogleMaps .

Diagnosis:— Distinguished from all other species in New Guinea by the ecirrate leaves with strongly grouped narrow lanceolate to linear leaflets, the leaflets of the most proximal group on each side of the rachis swept back across the sheathed stem, forming a chamber in which ants frequently make their nests; inflorescences long, flagellate, with distant primary branches and lax rachillae.

Medium-sized clustering rattan climbing to 30 m. Stem with sheaths 18–21 mm diam., without sheaths to 6–15 mm diam.; internodes 23–40 cm. Leaf ecirrate, to 60–150 cm long; sheath mid-green, drying pale green or pale brown, with thin sparse pale brown indumentum, sheath spines slender, persistent, usually abundant, usually rather uniform, 4–40 × 1–2 mm, with only slightly swollen bases, solitary, pale green, drying yellowish, horizontal, very narrow triangular, laminar, often larger spines interspersed with smaller spines; knee inconspicuous, scarcely swollen, to 27 × 16 mm, drying same colour as sheath, armed as the rest of the sheath; ocrea scarcely developed; flagellum present, 1.5–2 m long; petiole absent; rachis to 60–110 cm long, basally armed abaxially with slender spines as on the leaf sheath, adaxially armed with abundant erect spines, distally armed with recurved hooks; leaflets 23–30 on each side of rachis, arranged in 4–8 distant groups, crowded within the groups, those of the basalmost pair swept back across the stem, forming a chamber occupied by ants (?always), linear or very narrow lanceolate, longest leaflet in mid-leaf, basalmost leaflets to 5.5 × 0.6 cm, distalmost leaflets of basal group 20–28 × 1.8–3.5 cm, mid-leaf leaflets 21–31 × 1.5–3 cm, apical leaflets 9–10 × 1–1.2 cm, apical leaflets not joined, leaflets armed with short, dark, pale based spinules to 1 mm long, along 3 veins adaxially, margins, and midrib abaxially usually conspicuously so, but sometimes very inconspicuous, leaflets lacking indumentum, transverse veinlets conspicuous. Staminate inflorescence branched to 3 orders, to 80–250 cm long including the peduncle 63 cm long; prophyll to 21 × 1 cm, closely sheathing, splitting neatly at its tip, with a triangular lobe, covered with thin brown indumentum, unarmed; peduncular bracts absent; rachis bracts to 36 cm long with entire or lacerate tip and bearing scattered reflexed spines to 1.5 mm with swollen bases and scattered dark brown scales; primary branches up to 12, to at least 60 cm long, ca. 35–40 cm apart, with numerous rachillae; rachillae 4–24 × 2 mm; rachilla bracts 1 × 1.5 mm, distichously arranged, cup-shaped, with scattered dark brown scales, unarmed; floral bracteole 1.3 × 1.3 mm, triangular, unarmed. Staminate flowers not seen. Pistillate inflorescence to 4 m long, including peduncle to 2.5 m, branched to 2 orders; prophyll to 70 × 0.9 cm, tubular and closely sheathing, with a triangular lobe, bearing sparse brown indumentum and very sparsely armed with pale marginal spines to 8 mm; peduncular bracts 3, similar to prophyll, but more densely armed; rachis bracts similar to peduncular bracts; primary branches 3, to 90 cm long, with up to 22 rachillae; rachillae 5.5–10 × 0.25 cm; rachilla bracts triangular, 2 × 2 mm, distichous, very sparsely armed, and bearing scattered dark brown scales; proximal floral bracteoles 2 × 1 mm, distal floral bracteoles cup-shaped, 1 × 1 mm, scar from sterile staminate ca. 0.2 mm diam., borne on a cushion 1 mm diam. Sterile staminate flower not seen. Pistillate flowers not seen. Fruit (reconstructed from empty pericarp) globose, ca. 10 × 10 mm with ca. 22 vertical rows of pale brown scales with darker margins. Seed not seen. ( Fig. 10 View FIGURE 10 )

Distribution:— Scattered across New Guinea from Raja Ampat Islands to Gulf Province, Papua New Guinea, with a concentration of records in the Bird’s Head Peninsula.

Habitat:— Lowland forest at altitudes up to 640 m above sea level.

Uses:— Used for cordage and thatching.

Vernacular Names:— Are (Sayal), Sinsin (Merigem).

Specimens examined:— INDONESIA. Papua Province: Timika , 95 m, 4°45’S, 136°32’E, 11 July 1995, Maturbongs 191 (K!, MAN) GoogleMaps ; Timika, between Ajkwa and Otomona Rivers , on road Timika to Mile 38, 30 m, 4°26'22"S, 136°54'27"E, 10 February 1998, Dransfield et al JD 7662 (BH!, BO!, K!, L!, MAN!) GoogleMaps ; Timika, upstream from end of road to Kali Kopi river from mile 38, 95 m, 4°25'43"S, 136°57'7"E, 24 February 1998, Dransfield et al. JD 7721 (BH!, BO!, K!, L!, MAN!) GoogleMaps , Dransfield et al. JD 7723 (holotype K!, isotypes BH!, BO!, L!, MAN!) . West Papua Province: Sorong, Klasaman , km 14, 60 m, 0°55’S, 131°22’E, 15 September 1995, Maturbongs 276 (K!, MAN) GoogleMaps , 16 September 1995, Maturbongs 279 (K!, MAN) ; Sorong, Makbalim Village, Aimas , 25 m, 1°4’S, 131°24’E, 01 July 1997, Maturbongs 543 (K!, MAN) GoogleMaps , Maturbongs 545 (K!, MAN) ; Kota Sorong, Klasaman , 20 m, 0°55’37”, 131°20’7.3E, 2 February 2013, Baker et al. 1396 (BO!, K!, MAN!) ; Sorong Selatan, Sayal, Maampow , 10 m, 21 February 2003, Heatubun et al. 417 (BO, K!, MAN) ; Wasior, Senderawoi Village , 26 February 2000, Maturbongs et al. 651 ( AAU, BRI, K!, L, MAN) ; Kecamatan Ayfat, Ayawasi , 450 m, 1°9’S, 132°29’E, 14 February 1995, Yumte 198 (L!) GoogleMaps ; Merdey Subdistrict , 640 m, 1°35’S, 133°20’E, 01 August 1998, Wally 834 (BO, K!, MAN) GoogleMaps ; Fak-Fak District, Yamur Village, Buama river , km 45 of logging road of PT. Kaltim Hutuma , 50 m, 01 February 2001, Maturbongs et al. 668 (BO, K!, LAE, MAN) . PAPUA NEW GUINEA. Sandaun Province: Bewani , lowland, 0 m, 3°1’S, 141°8’E, 19 March 2000, Barfod 489 ( AAU, BRI, CANB, K!, LAE) GoogleMaps . Gulf: Malalaua Subdistrict, Merigem, near Kakoro-Bulldog , 60 m, 7°49'30"S, 146°29'30"E, 24 November 1972, Zieck & Kumul NGF 36532 View Materials (BH, CANB, K!, L, LAE!) GoogleMaps .

Notes:— This rattan ( Fig. 10 View FIGURE 10 ) is easily distinguished by its ecirrate leaves with strongly grouped narrow leaflets, the basalmost of which are swept back across the stem (hence the specific epithet), forming a chamber in which ants make nests. The leaf bears a striking resemblance to C. laevigatus Mart. ex Walpers (1852: 489) , a widespread species in western Malesia. However, this latter species is cirrate and eflagellate (rather than ecirrate and flagellate) and belongs to an entirely different group of Calamus (section Phyllanthectus Furtado [1956: 81] rather than section Calamus [synon. section Coleospathus Furtado 1956: 157]).

Calamus retroflexus is unlikely to be confused with other species in New Guinea. However, there are several specimens in the herbarium that are less typical of the species that we have illustrated here and we are not entirely sure of their identity. A series of collections made by Wanda Avé from limestone at Ayawasih on the western end of the Bird’s Head Peninsula share features with Calamus retroflexus . Most of the collections, however, are sterile and are very much more slender than typical C. retroflexus (Avé 4166, 4168, 4169, 4170, 4171, 4172, 4176, 4341). Two of the collections are fertile (Avé 4221 – dead staminate flowers, and Avé 4341 – fruiting). In size these two collections approach typical C. retroflexus , but they differ in having highly condensed leaves and crowded leaflets, the whole specimens having the appearance of being from a montane habitat, yet these were collected on limestone at relatively low elevation (450 m). We are sure that the slender sterile collections are conspecific with these two fertile collections, but this suggests that juvenile stems are much more slender than adults, a situation not unknown in rattans, but certainly unusual. We have observed similar possible dimorphism at Klasaman, near Sorong in lowland C. retroflexus . More field work is required to substantiate our inferences. Currently, we include Wanda Avé’s collections tentatively in C. retroflexus .

A further collection, Heatubun 137, from Waigeo Island in the Raja Ampat group is reminiscent of C. retroflexus , but the stems are very slender, the sheath armature is sparse and composed of short black-tipped spines unlike typical Calamus retroflexus . Without fertile material we are unable to identify this with certainty.


Universitas Negeri Papua


Addis Ababa University, Department of Biology


Queensland Herbarium


Papua New Guinea Forest Research Institute


Australian National Botanic Gardens