Calamus erythrocarpus W.J.Baker & J.Dransf., 2017

Baker, William J. & Dransfield, John, 2017, More new rattans from New Guinea and the Solomon Islands (Calamus, Arecaceae), Phytotaxa 305 (2), pp. 61-86 : 65-67

3. Calamus erythrocarpus W.J.Baker & J.Dransf. , sp. nov. Type:— PAPUA NEW GUINEA. Central Province: Sogeri

Subdistict, near Jawarere (Subitana), 450 m, 9°25’S, 147°25’E, 3 September 1968, Zieck NGF 36176 (holotype LAE!,

isotype BH, L!)

Diagnosis:— Distinguished by the moderately robust, clustering habit, the subcirrate leaf with few broadly lanceolate, cucullate leaflets, the longest leaflets at the base of the leaf, the leaf apex bearing a vestigial leaflet pair remnant or a short cirrus, the leaf sheaths armed only with few, minute spines, the short inflorescences lacking peduncular bracts, the rachis bracts significantly exceeding the primary branches and splitting to the base (not tattering), and the rounded red fruit covered with unchannelled, erose-margined scales.

Moderately robust, clustering rattan climbing to ca. 40 m. Stem with sheaths 12–23 mm diam., without sheaths to 9–13 mm diam.; internodes 24–40 cm. Leaf subcirrate, to 70–97 cm long including subcirrus and petiole; sheath mid-green when dry, with thin, pale grey caducous indumentum of matted hairs and irregular scales, almost unarmed with the exception of very few, scattered, minute, upward-pointing, brown-tipped spines to ca. 0.5 mm long; knee 24–28 mm long, 10–20 mm wide, colour and indumentum as sheath, unarmed; ocrea a low, tightly sheathing, unarmed, leathery crest encircling leaf sheath, 7–13 mm high, darker than sheath, unarmed, leathery, persistent; flagellum to 220 cm long; petiole 2–7 cm long, 5–8 mm wide and 3–4.5 mm thick at base, rounded adaxially, flattened abaxially, indumentum as sheath, unarmed or armed with solitary grapnel spines; rachis ca. 60–90 cm, moderately armed with grapnels; leaflets 8–11 each side of rachis, subregularly arranged, rather widely spaced 3.5–11 cm apart, broadly lanceolate, usually cucullate, longest at base 23–37 × 2–5 cm, mid-leaf leaflets 22–34 × 3–5 cm, apical leaflets highly reduced to a vestigial remnant 2.2–3.7 × 1–2 cm, or even reduced to a fibre-like structure ca. 1.2 × 0.1 cm, the leaf apex then resembling a short cirrus, leaflets unarmed and glabrous, with the exception of a very few, fine, marginal bristles near apex of some leaflets, transverse veinlets moderately conspicuous. Staminate inflorescence compact, erect, possibly arching when mature, 40–55 cm long including ca. 20 cm peduncle, lacking flagelliform tip, branched to 3 orders; prophyll 24–31 × 12–17 cm, tubular, with asymmetrically acute tip, keeled, apparently splitting on maturity, indumentum as sheath, unarmed; peduncular bracts lacking, rachis bracts 2.5–18 × 0.8–1.7 cm, similar to prophyll, but splitting to base to expose primary branches, overlapping, at least two times longer than primary branches, unarmed; primary branches ca. 6, to 3–6 cm long, ca. 5 cm apart, compact, finely branched, exceeded by and enclosed within rachis bracts, with numerous rachillae, moderately well-developed bracts on main axis; rachillae 3–10 mm × ca. 0.5 mm, straight; rachilla bracts 1.5 mm long, triangular, subdistichous, inconspicuous; floral bracteole 0.2 × 0.5 mm, shallow cup-shaped. Staminate flowers 1.2–2 × 1–1.2 mm in early bud (only immature material available); stamens 6. Pistillate inflorescence similar to staminate inflorescence, erect, ca. 37 cm long including ca. 9 cm peduncle, lacking flagelliform tip, branched to 2 orders; prophyll ca. 22 × 1.7 cm, tubular, but split deeply to base by emerging subtended primary branch, exceeding the primary branch by more than twice its length, indumentum as sheath, unarmed; peduncular bracts lacking, rachis bracts similar to staminate inflorescence rachis bracts in dimensions, overlapping, splitting deeply to base by emergence of primary branches and the remainder of the inflorescence, but typically remaining tubular at the tip, unarmed; primary branches ca. 4, 2–6 cm long, ca. 4 cm apart, erect, sparsely branched, exceeded by and enclosed within prophyll and rachis bracts, with up to 9 rachillae, bracts as in staminate inflorescence; rachillae 3–27 mm × 1–2 mm, straight; rachilla bracts 0.5 × 1.5 mm, distichous, tubular; proximal floral bracteole 1 × 1.5 mm, distal floral bracteole 1 × 1 mm, scar from sterile staminate peg-like and protruding to side of pistillate scar. Pistillate flowers not seen. Sterile staminate flowers not seen. Fruit ellipsoid, ca. 16 × 11 mm including beak 1.5 × 1 mm, with ca. 13 longitudinal rows of red, smooth, unchannelled scales with erose margins. Seed (sarcotesta removed) 9 × 8 × 5.5 mm, ellipsoid with deep lateral pit; endosperm homogeneous; embryo basal.

Etymology:— The specific epithet refers to the red colour of the fruit.

Distribution:— Known from many gatherings at a single locality in hills 35 km east of Port Moresby, Central Province.

Habitat:— Rain forest on lower slopes and bottom of a creek valley, ca. 460 m.

Uses:— None recorded.

Vernacular names:— Ohana (Goari).

Specimens examined:— PAPUA NEW GUINEA. Central Province : Sogeri Subdistict, near Jawarere (Subitana), 460 m, 9°25’S, 147°25’E, 3 September 1968, Zieck NGF 36176 (holotype LAE!, isotype BH!, L!), 1 October 1968, Zieck NGF 36181 ( BH!, LAE!) ; Sogeri Subdistict , Subitana, 460 m, 9°25’S, 147°32’E, 4 February 1970, Zieck NGF 36233 ( BH!, LAE!) .

Notes:— Calamus erythrocarpus is a member of the Calamus anomalus complex.All species of this group produce relatively short inflorescences that are unarmed (except for the prophyll in some instances), lack a flagelliform tip, and bear overlapping, papery bracts that exceed the internode above and that are punctured or split by the relatively short, emerging inflorescence branches. Most species of this group ( C. anomalus Burret [1935: 320] , C. erythrocarpus , C. essigii Baker [2002: 720] , C. nannostachys [1931: 264]) have a rather narrow distribution restricted to the Owen Stanley Range in Central Province and adjacent Northern Province in south-eastern Papua New Guinea, where they are separated along an elevational gradient, whereas C. maturbongsii Baker & Dransfield (2002: 725) occurs in the vicinity of Sorong in far western Indonesian New Guinea. This striking disjunction constitutes a 1700 km gap in distribution records. Even more remarkably, C. erythrocarpus grows in close proximity with C. anomalus and C. essigii , with the closest site records separated by just ca. 3–5 km, but its morphology indicates that it is very closely related to the disjunct C. maturbongsii . In fact, initially we regarded C. erythrocarpus and C. maturbongsii as the same species, but closer study has revealed important differences.

Similarities that are shared by C. erythrocarpus and C. maturbongsii , include the moderately robust, clustering habit, overall leaf structure (few broadly lanceolate, cucullate leaflets, longest leaflets at the base of the leaf), almost glabrous leaf sheaths armed only with few, minute spines, and the robust inflorescence relative to other members of the group. Their fruit are strikingly similar in their shape, colour (red in C. erythrocarpus , orange in C. maturbongsii ), in the structure of their rather flat scales with erose margins, and in the smooth seed within. The most obvious difference is the subcirrate leaf of C. erythrocarpus in which the apical leaflets are highly reduced to a vestigial remnant no more than 4 cm long that in one specimen is reduced to a fibre-like structure, the leaf apex then resembling a short cirrus. The apical leaflets of C. maturbongsii are a more typical leaflet pair that are not united or partly united by one quarter of their length. Only pistillate inflorescences are known for C. maturbongsii , but these are much longer than pistillate inflorescences of C. erythrocarpus (62–81 cm long as opposed to ca. 37 cm), primarily due to the much longer peduncle that bears peduncular bracts, which are not observed in either pistillate or staminate material of C. erythrocarpus . The rachis bracts of C. maturbongsii split deeply and also tatter, while C. erythrocarpus bracts split deeply, but do not tatter. The primary branches of C. erythrocarpus pistillate inflorescences bear fewer rachillae (up to nine in available material, compared to up to 17 in C. maturbongsii ).