Piper arfakianum C.DC.

Gardner, R. O., 2013, Piper (Piperaceae) in New Guinea: the climbing species, Blumea 57 (3), pp. 275-294 : 277-280

2. Piper arfakianum C.DC. — Fig. 1c , 2a– i ; Map 1

Piper arfakianum C.DC. (1917) 127; Chew (2003) 15. — Type: Gibbs 5525 (iso K, L n.v.), Arfak Mts, Angi Lake, [c. 1800 m].

Piper pilosulinodum C.DC. (1917) 128; Chew (2003) 15. — Type: Gibbs 5624 (holo BM; iso K n.v.), Arfak Mts , Koebre Ridge.

Fertile-shoot internodes c. 2 mm diam, nearly smooth. Vegetative parts (at least, stipule, newest internodes and petiole) with patent pale to mid-brown bristly-flexuose hairs to c. 1 mm long. Stipule to c. 1 cm long. Leaf blade chartaceous to subcoriaceous, ovate (or elliptic-oblong), 4 –7(–10) by 1.5 –4.5 cm; base symmetrical, usually shortly cordate to rounded, subequal at petiole and usually shortly incurved there, apex long-acuminate; main lateral nerves 1–2 pairs, basal, narrowly prominent above; surfaces of blade sometimes red-glandular. Petiole 0.5 –1.5 cm long, usually c. 1/6 as long as blade. Male inflorescence not seen. Infructescence a spike c. 4 –8 cm long, c. 0.5 cm diam, on a peduncle c. 1–2 cm long; rachis sparsely hirsute, bracts subsessile, glabrous to villous, bract-heads 0.5 –1.3 mm diam, held at or just below apex of fruitlets. Fruitlets free, 1.2– 2 mm diam, broadly rounded to flattened above but usually beaked by a stout style c. 0.25 mm long; stigmas 3, broadly oblong, together c. 0.35– 0.5 mm diam.

Distribution — New Guinea:Arfak Mts to Milne Bay Province.

Habitat & Ecology — Small climber or scrambler in montane moss forest, ridge thickets, and Nothofagus -dominated forest; c. 1900 – 2900 m altitude.

Notes — This species seems to be an uncommon one. I accept twelve of the thirteen extra-typical collections listed by Chew (2003: 16). They are mainly from Papua New Guinea, and I cannot add any new localities there or for the island as a whole. With respect to the thirteenth listing, Schodde 1556, I place this in P. macropiper ( Fig. 6j ).

Recognized by its small to medium-sized, ovate-triangular, long-acuminate leaves, which are usually coarsely bristly on the petiole and venation below. The major nerves all depart the midrib from 0 – 5 mm above the blade base, and the blade’s basal margins are usually shortly incurved before the midrib channel is reached.

These features help distinguish the species from P. subcanirameum (shortly acuminate apex, glabrous, nerves departing from up to 1.5 cm from petiole base, blade margins decurrent down into sides of petiole). Both species have rather coriaceous and glossy leaves but there is a textural difference: in P. arfakianum the lesser venation is seldom as prominent above as it is in P. subcanirameum . Possibly the leaves of the former are, in life, relatively fleshy, but label-notes are inadequate on this point.

Material from the western part of the island has consistently smaller leaf blades (to c. 6 2.5 cm) than those from Mt Kaindi and further eastwards.

Kostermans 2382, from the type locality, differs in its leaves being appressed-villous above and below.

Chew (2003) saw isotypes of P. pilosulinodum C.DC. and found them not to differ significantly from the present species. Having seen Van Royen & Sleumer 7456 (Tamrau Mts, Mt Nettoti, CANB), said by Chew (2003: 15) to be a good match for the P. pilosulinodum types, I agree.

Figures

Map 1 Distribution of Piper arfakianum C.DC. in New Guinea. Representa- tive specimens.

Fig. 1 Specimens of Piper species. – a. P. abbreviatum Opiz. – b. P. cf. amboinense (Miq.) C.DC. – c. P. arfakianum C.DC. – d. P. betle L. (a: Brass 28658; b: Kanehira & Hatusima 11500; c: Sleumer & Vink 4433; d: Craven & Schodde 858, all A).

Fig. 2 Piper species.Fertile-shoot leaves and female inflorescence (‘infr.’),immature infructescence (‘infl/fr’) or ripe infructescence (‘infr.’). — a–i: P. arfakianum C.DC.; a. Brass 5029, Mt Tafa 2400 m, infl.; b. Brass 22534, Mt Dayman 2200 m, infl./fr.; c. Brass 22729, Mt Dayman 2150 m, infr.; d. Kanehira & Hatusima 13708, Angi 2200 m; e. Kostermans 2382, Angi Lake, 1800 m; f. LAE 60357, Mt Kaindi 2057 m, infr.; g. NGF 23627, Mt Kaindi 2300 m, h. NGF 30867, Mt Kaindi 2150 m, infr.; i. Sleumer & Vink 4433, Angi Lake 1950 m, infr. — j–s: P. subcanirameum C.DC.; j. Clemens 11215 p.p., Matap, Morobe Prov. c. 1600 m, infl/ fr.; k. Durand & Nelson 146 (HUH herb. Gray), Mt Kaindi 2650 m, infr.; l. LAE 57084, Ialibu 2515 m; m. NGF 19985, Edie Creek 2950 m, infr.; n. NGF 24994, Ialibu 2000 m, infr.; o. NGF 30885, Edie Creek 2050 m, infr.; p. Schodde 1861, Mt Giluwe 3050 m; q. Takeuchi 5756, Mt Wilhelm 2800 m, infl/ fr.; r. Takeuchi 10702 (BRIT), Bismarck Range 2040 m; s. Takeuchi 20136, Porgera 2900 m, infr. (all from A except as noted). — Scale bar = 5 cm.

Fig. 6 Piper macropiper complex. Fertile-shoot leaves and ripe infructescences (shortened by half in h, k). — a–e: P. breviantherum C.DC.; a. Craven & Schodde 1093, Aseki Patrol District 1600 m; b. Gardner 7068 (AK), Kaironk Valley 1700 m; c. Hoogland & Pullen 6163, Mt Hagen Ra. 2550 m; d. Hoogland & Schodde 6914, Yaki River 2450 m; e. Kalkman 5200, Mt Ambua 2650 m. — f –i: P. macropiper s.str.; f. Brass 13976, Idenberg R. 55 m; g. Brass 25216, Goodenough I. 150 m; h. Brass 31596, Okapa, Eastern Highlands 1950 m; i. Takeuchi 5337, Hunstein Ra.; j. Schodde 1556, Anga Valley 2000 m. — k, l. P. novoguineense Warb.; k. Gardner 9009 (AK), Kaironk Valley 2100 m;l. Pullen 411, Asaro-Mairifutica Divide 2600 m. — m –o. P.rodatzii K.Schum.& Lauterb.; m.Brass 24658, Goodenough I. 1600 m; n. Brass 30479, Mt Wilhelm 2770 m;o.Takeuchi 20143, Porgera 2900 m (all from A except as noted). — Scale bar = 5 cm.