Sahulia , a new endemic genus and a generic key to Sapotaceae in New Guinea
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ISSN: 0075-5974 (print) ISSN: 1874-933X (electronic)
Sahulia, a new endemic genus and a generic key to Sapotaceae in New Guinea Ulf Swenson1
& Jennifer Kearey1
Summary. Sahulia suboppositifolia (Sapotaceae, Chrysophylloideae) is described and illustrated as a new monotypic genus from New Guinea. The species is so far only known from four collections made in lowland tropical rainforest near Lake Murray in the west and Koitaki east of Port Moresby. As a member of Sapotaceae with white latex, entire leaves, and flowers in fascicles, it is readily distinguished by the combination of opposite leaves, non-areolate venation, and almost 10 mm long green flowers with a bristle-like corolla margin consisting of short, rather thick, and pointing trichomes. We also provide a new generic key to Sapotaceae for New Guinea. Key Words. new genus, Papua, Planchonella, taxonomy.
Introduction Dutch botanists have long been very active in studying the flora of New Guinea, not the least Lam (1932), van Royen (1957), and Herrmann-Erlee & van Royen (1957). Before molecular techniques were available, the classification of Sapotaceae was unstable with, for example, Planchonella Pierre being accepted, subsumed, resurrected, and again subsumed in Pouteria Aubl. (Dubard 1912; Baehni 1942; van Royen 1957; Pennington 1991). With the introduction of molecular and phylogenetic techniques, a new classification of Sapotaceae has been developed. Planchonella is evidently a good natural group while Pouteria is now restricted to species occurring in the New World and found in Asia and Oceania only as cultivated or escaped plants (Swenson & Anderberg 2005; Swenson et al. 2008, 2013; Faria et al. 2017). Phylogenetics have revealed that species in New Guinea and New Caledonia earlier classified in Pouteria are better placed in Pichonia Pierre, Planchonella, Pleioluma (Baill.) Baehni, Pycnandra Benth., Sersalisia R.Br., and Van-royena Aubrév. One species with an aberrant combination of morphological characters, not corresponding to any of these natural groups, is Planchonella suboppositifolia H.J.Lam. Planchonella suboppositifolia was described by Lam (1932) from New Guinea as "A remarkable plant, allied to P. chartacea (v.Muell.) H.J.L. from N. Australia, ...", without further comment. The species was later transferred to Pouteria by Baehni (1942), followed by van Royen (1957) who again placed it in Planchonella, citing only three (or four) available specimens. It differs from all other Planchonella in having opposite leaves (not alternate), tertiary veins perpendicular to the midvein (not reticulate or
oblique), a sparsely pubescent corolla (not glabrous), and stamens that are inserted near the middle of the corolla tube (not close to the tube orifice). It further differs from other members of Sapotaceae in New Guinea such as Magodendron Vink, Pichonia, Pleioluma, and Sersalisia in the absence of the characteristic higher areolate leaf venation. One specimen (Pullen 7499), collected in 1967, housed in the Leiden herbarium, was studied by T. D. Pennington f
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