Aristolochia chrismülleriana W.N.Takeuchi, W. N. Takeuchi. A, 2013

Takeuchi, Wayne, 2013, Floristic records from the upper Sepik of Papua New Guinea: Aristolochia chrismülleriana sp. nov. (Aristolochiaceae), Monanthocitrus paludosa (Rutaceae), and Secamone timorensis (Apocynaceae), Phytotaxa 114 (1), pp. 51-57 : 53-56

Aristolochia chrismülleriana W.N.Takeuchi , sp. nov. ( Fig. 3 )

Aristolochiae jackii Steud. affinis sed floribus minoribus usque ad (41–) 50–59 mm longis fructibus globosis (vel

obovoideis) minoribus usque ad 39 × 38 mm differt.

Type: — PAPUA NEW GUINEA. East Sepik Province: April River, lower slopes of Kamelsrücken, opposite Natawe ,

swampy forest, 4°35'S, 142°33'E, 70 m, 27 November 2007, Takeuchi, Towati & Ama 22417 B (holotype A!;

isotypes BO!, K!, L!, LAE!).

Twining vines, glabrous. Stems terete, 1.5–3(–4.5) mm diameter in the leafy intervals, sulcate, brunnescent to black, abscission scars absent; internodes (1–)10.5–18.5(–26) cm long. Leaves spirally inserted, obliquely spreading, exstipulate; petioles 25–45(–54) × 0.8–1.5(–2) mm, sigmoid or not, proximally swollen (pulvinus to 2.5 mm wide), distally expanded, deeply channelled on upper side, other surfaces shallowly scored by longitudinal grooves, not articulated; leaf-blades membranous-chartaceous, wider than long, (9.9–)10.5–13.8(–15) × 10.3–15.2(–18.6) cm, united in the lower (2.6–) 3.3–5.5 cm, 3-partite (rarely trullate); central lobe largest, (4.3–)6.3–10.6 × 4.3–7.8 cm, usually widest above the middle; lateral lobes 3.5– 6.3(–7.5) × 1.7–3.7 cm, falcate (or divergent on trullate blades); lamina base truncate, abruptly cuneate (ca. 2– 5 × 3–7 mm) at the petiole; margins revolute; apices acute-acuminate (on the central lobe) or obtuse (on lateral lobes); surfaces adaxially smooth, abaxially pustulate, bifacially olivaceous to fuliginous; venation 5(– 7)-palmate, basal 1–2 pairs the weakest, anastomosing, innermost primaries (3) serving the central leaf-lobe, reaching the margin or nearly so; crossing nerves proximally subscalariform; reticulations conspicuous, loose, irregular; all veins/nerves distinctly raised on both sides. Inflorescence axillary, racemose, 3.5–9 cm long, surfaces black (excepting the perianth); peduncle 3–7 × 0.8–2 mm (or absent); axis 30–50(–61) × 0.3–0.8(– 1.2) mm, striate, straight (or slightly zig-zag); anthetic pedicels 8.5–12.5 × 0.2–0.7 mm; bracts ovate, 0.6–1.3 × 0.8–1.2 mm, acute, concave, ciliolate, adaxially glabrous, diverging, persisting. Flowers 4–14 per raceme, (41–) 50–59 mm long, zygomorphic, bisexual; ovary cylindrical-fusiform, 5–7 × 0.7–1 mm, grooved; perianth (perigone) a synsepalous calyx, (36–) 46–55 mm long, 1-labiate, petaloid, venose, brown to fuliginous, tubiform in early bud; utricle 4–5 mm stipitate, broadly ellipsoid, 9.5–12 × 5–8 mm, biglandular, reducing to a straight 8–10.5 × 1.5–1.8(–2.3) mm tube at the syrinx, sparsely papillate-puberulent in the syrinx-tube, glabrous on all other surfaces; perianth limb 23–29 mm long, hastate at the base (7.5–8 mm wide), distally oblong-spathulate, entire, costate, obtuse; gynostemium obovoid, ca. 2.5 × 1.5–2.5 mm; stamens 6, anthers 2- celled, 0.6–0.7 mm long, extrorse, overtopped by the cupuliform base of the style-head; style-lobes 6, conical, incurved, connivent. Infructescence from axils of attached leaves, pendulous, ebracteate; fruiting pedicels accrescent, to 53 × 3 mm, wider towards the apex, compressed, furrowed, not articulated. Capsules globose (or obovoid), (32–)36–39 × 32–38 mm, marked by 12 longitudinal lines, transversely wrinkled between sutures, brown or fuliginous; seeds deltate, 8–11 × 8–12 mm, alate, flat, numerous, tightly arranged in vertical columns within each locule, pale brown, smooth, wings papery, 1–2 mm wide.

Etymology: — Aristolochia chrismülleriana is named after Chris Müller, a geologist by profession (Country Manager, Papua Mining) and a lepidopterist by avocation.

Field characters: —Leaves 3-lobed, coriaceous, dark green above, yellow green underneath; flowering pedicels flaccid; perianth pale brown or brownish-green, faintly odorous (mid-afternoon); fruits pendulous, spheroid-obovoid, ca. 3.5 cm diameter.

Distribution: — East Sepik Province, known with certainty from Angoram and the April River at Kamelsrücken ( Figs. 1 , 4 ). Populations have also been seen (pers. obs.) along the Sepik main channel near the Aprilfluss junction ( Fig. 5 ).

Habitat and ecology: —Lowland riparian and swamp forest, in regrowth at 30–70 m.

Phenology: —Flowering and fruiting in September–November.

Additional specimen examined (paratype): — PAPUA NEW GUINEA. East Sepik Province: Angoram subdistrict, track from Timbunke to Kwoiwut , climber on low secondary growth in riverside clearing, 100 ft (30 m), 5 September 1959, Pullen 1648 ( LAE!) .

In the latest revision of Malesian Aristolochiaceae ( Ding Hou 1983, 1984) the new species described here had been provisionally assigned to A. jackii Steudel (1840: 141) , a plant recorded from the Malay Peninsula, Sumatra, Java, Borneo, and Palawan. The unusual 3-partite leaf in A. jackii was a principal basis for referring the Sepik population to the west Malesian species.

Although phytogeographically improbable, Ding Hou's interpretation of A. jackii was not unreasonable within the context of then-existing knowledge. Flowers and fruits from the "conspecific" Sepik population were unknown until recently, leaving only the vegetative characters for comparative evaluation. With complete material from PNG now in hand, the presumed relationship can finally be reassessed.

While undoubtedly related to A. jackii , the new species differs in the following obvious respects (corresponding characters for A. jackii in parentheses): leaf-blades abruptly cuneate from a truncate base, never cordate (leaf-blades usually cordately based); flowers glabrous or nearly so on all surfaces, with only widely scattered papilliform hairs in the syrinx-tube (tomentose-villose on the limb, obviously hairy on interior surfaces); perianth brown or brownish-green, 3.6–5.5 cm long (perianth red to purple brown, 7.5–11 cm long); and fruits globose-obovoid, to 3.9 × 3.8 cm (fruits oblong, 5–6 × 2.5 cm).

Malesian Aristolochia Linneus (1753) was divided by Parsons (1996) into two genera, the species with indehiscent fruits being segregated as Pararistolochia Hutchinson & Dalziel (1927: 75) . Irrespective of whether this interpretation is adopted, the new species (with clearly capsular fruits), is an Aristolochia in the traditional sense as treated by Ding Hou (1983, 1984).

Aristolochia chrismülleriana is the third member of its genus s. l. to be typified from the April River. The other congeners were discovered by the Kaiserin-Augusta-Fluss Expedition of 1912–13, and have never been found again since the loss of their types in World War II.

Figures

FIGURE 1. Kamelsrücken (Camel Back), type locality for Aristolochia chrismülleriana. A, the aptly named topographic feature can be instantly recognized by its summit profile. Etappenberg is located on east-facing slopes of the twin peaks. B, April River.

FIGURE 3. Aristolochia chrismülleriana W.N.Takeuchi. A, aspect (compare with Ding Hou 1984: 89, fig. 9); B, anthetic flower: B1, utricle, B2, syrinx tube, B3, limb; C, mature fruit. A–C from Takeuchi, Towati & Ama 22417B.

FIGURE 4. Island of New Guinea. Collection localities from the text. A, Hollandia (present-day Jayapura); B, Aprilfluss junction; C, Waskuk Hills; D, Natawe-Kamelsrücken; E, Angoram.

FIGURE 5. The Aprilfluss (April River) at its confluence with the Sepik main channel. A, Sepik River; B, April River. Alluvial successions are the dominant formation along both watercourses, providing characteristic habitat for Aristolochia chrismülleriana.