Ventilago crenata Cahen & Utteridge, 2017

Cahen, Daniel & Utteridge, Timothy M. A., 2017, Three new species of Ventilago (Rhamnaceae) from South-East Asia, Phytotaxa 307 (3), pp. 171-182 : 173-174

Ventilago crenata Cahen & Utteridge sp. nov., Fig. 1

Ventilago crenata is related to Ventilago microcarpa K.Schum. in Schumann & Hollrung (1889: 72) and Ventilago papuana Merrill & Perry (1941: 263) , but differs in its leaves, which have crenate margins, fewer secondary veins that are more elevated abaxially, a shorter petiole and tufts of hairs in secondary vein axils. The species also differs in its flowers, whose nectary disks are glabrous.

Type:— PAPUA NEW GUINEA. Northern Division [Oro Prov.]: Pongani valley near Dareki village , Managalese area , Rain forest on broken lava slope, ca. 2100 feet [650 m], 13 August 1964, Pullen 5672 (holotype: L!; isotypes: GH!, LAE n.v.) .

Climber, woody. Indumentum sparse at base of branchlets, dense at distal end of branchlets; hairs cinereous to fulvous, spreading to appressed-antrorse. Branches slender, terete, smooth, reddish-brown; branchlets ridged. Stipules fugaceous. Leaves with lamina narrow ovate to elliptic, 5.1–10.8 cm long, 2.4–5.0 cm wide, chartaceous-subcoriaceous, slightly shiny adaxially, abaxial lamina bearing small rounded glandular spots, apex slightly attenuate to rounded, blunt to mucronulate, base usually asymmetric, rounded to widely cuneate, margins irregularly crenate, apical end of crenations tipped with a minute callosity; primary vein abaxially sparsely hairy, elevated and drying with a red colour; secondary veins 4–6 pairs, decurrent along the primary vein, abaxially sparsely hairy, elevated, unbranched and remaining separate, tertiary veins perpendicular to the primary vein, most spaced by c. 0.5 mm from each other, forming distinct horizontal lines on both sides of lamina, higher order venation reticulations distinct; domatia present, tufts of hairs in secondary vein axils; petiole 2–7 mm long, sulcate, hairy. Inflorescence fascicles with the leaves bearing them fugaceous so that fascicles are arranged in racemes or panicles with racemes to ca. 7 cm long at young fruiting stage, raceme rachis ca. 0.9 mm wide at base. Flowers pedicellate with a hypanthium ca. 1.1 mm wide, bisexual, 5-merous, perigynous; sepal lobes triangular, adaxially keeled with an apical protuberance; petals present, clawed, hairy abaxially, obcordate, each enclosing a stamen before anthesis; androecium apostemonous, anthers 5, dorsifixed, introrse; disk subpentagonal, filling the hypanthium, fleshy, glabrous, yellow; ovary hairy, half-immersed in disk, locules 2; style 2-fid. Fruit densely hairy when young, apex with style remains persistent, divergent and recurved.

Distribution:— New Guinea (Central, Oro and Southern Highlands Provinces) ( Fig. 2 ).

Habitat:— New Guinea Central Range montane rain forests and south-eastern Papuan rain forests ; elev. 30–800 m.

Conservation status:— Near Threatened (NT). Given that only three localities are known for the taxon, it meets the AOO requirements under criterion B for threatened. Also, based on the data available, the taxon’s distribution is severely fragmented. However, its EOO is greater than 29,000 km 2, and a relatively stable conservation status of New Guinean rain forests ( Morrison 2001a, 2001b) suggests that the population may not be declining. Schodde 2418 was collected within Lake Kutubu Wildlife Management Area (IUCN Category not reported). The other two collection localities are not within protected areas.

Phenology:— Collected in flower from August to October.

Etymology:— The specific epithet refers to the leaf’s crenate margin.

Discussion:— Ventilago crenata is recognised by its irregularly crenate leaf margin, 4–6 pairs of abaxially elevated secondary veins, tufts of hairs in secondary vein axils, 2–7 mm long petiole and glabrous nectary disks. The only other taxa of Ventilago found in New Guinea are V. microcarpa , and V. papuana , which have entire leaf margins, 6–8 pairs of secondary veins that are almost flat abaxially, no domatia at secondary vein axils, a 5–13 mm long petiole and hairy nectary disks. Ventilago microcarpa and V. papuana can be recognised on the leaf size with V. microcarpa having leaves to 7 cm long on petioles up to 6 mm long, with V. papuana having leaves to 12 cm long on longer petioles 6–9 mm long.

The specimen collected at a low elevation (ca. 30 m) on alluvium near the Mori River (Pullen 8188) differs from the type specimen and Schodde 2418 collected at 650–800 m in its narrower leaves with almost entire leaf margins and long and much-branched panicles. However, its morphology is clearly more similar to that of V. crenata than it is to that of V. microcarpa and V. papuana , in particular this specimen has 4–6 pairs of elevated secondary veins, short petioles and glabrous yellow nectary disks.

Of the specimens currently available for study, winged fruits can be observed only on Pullen 5672. However, they are at an early development stage, and the characteristic Ventilago globose seed chamber in the fruit’s lower portion could not be observed with the material available for study. If mature fruits bear an inconspicuous, flat and elongated seed chamber, V. crenata would in fact be a member of Smythea . However, the presence of flower fascicles in leafless racemes and the absence of papillae on nectary disks suggest that V. crenata is a member of Ventilago .

Additional specimens examined:— PAPUA NEW GUINEA. Central Province: Mori River, c. 15 km NE of Cape Rodney, rain-forest on alluvium, 10°04’ N 148°32’ E, ca. 30 m, 1 September 1969, Pullen 8188 (L!). Southern Highlands Province: Lake Kutubu , near Moro, primary forest ; ca. 2700 feet [800 m], 6 October 1961, Schodde 2418 ( GH!, L!) .

Figures

FIGURE 1. Ventilago crenata. A habit. B leaf, abaxial view. C detail of marginal venation pattern, abaxial view. D detail of asymmetric leaf base, abaxial view. E detail of abaxial midrib showing domatia. F flower. G flower, longitudinal section. H petal, abaxial view. I immature fruit. Scale bar: A = 3 cm; B = 2 cm; C, D = 5 mm; E, F, G = 2 mm; H = 1 mm; I = 4 mm.All from Pullen 5672. DRAWN BY LUCY T. SMITH.

FIGURE 2. Distribution of Ventilago crenata (●).