Two new species of Dilkea subgenus Dilkea (Passifloraceae) from Loreto, Peru

Abstract Two new species of Dilkea subgenus Dilkea (Passifloraceae) are described from Loreto, Peru. Dilkea hebes Feuillet, sp. nov., has leaves with elliptic to oblanceolate blades that are dull adaxially, and spherical fruits with thick walls; Dilkea nitens Feuillet, sp. nov., has leaves with narrow-ovate blades that are shiny adaxially, and fruits with an apical cone and thin walls. A key to the species of subgenus Dilkea is provided.


Introduction
Dilkea Mast. belongs in the Passifl oraceae Juss. ex Roussel subfamily Passifl oroideae Burnett tribe Passifl oreae DC. and currently includes 12 Neotropical species including the two described below. Among the New World genera of Passifl oraceae, Dilkea is a distant second to Passifl ora L. with its ca. 550 species.
Dilkea is characterized by tetramerous fl owers with 8 stamens, a set of 4 carpels with 4 styles fused in the basal third, an androgynophore lacking or rarely sub-null, the operculum lacking, and seeds of a peanut shape and size, while Passifl ora has pen-tamerous fl owers with 5 stamens, an androecium with 3 carpels with 3 free styles, a well-developed androgynophore, an operculum of various shapes, and seeds fl attened and usually much smaller. Th e two other Neotropical genera each with 2-3 species are tetramerous like Dilkea, but Mitostemma Mast. has free styles and the species of Ancistrothyrsus Harms are hairy throughout and their fruits are capsular, while Dilkea species are glabrous and their fruits are baccate.
In the past few years, I came across many collections of Dilkea, a genus previously poorly collected. Six species are presently recognized in subgenus Epkia Feuillet (2009) and are often confused with Clavija Ruiz & Pav. in the Primulaceae (APG III 2009). New species from the Guiana Shield have been described recently (Feuillet 2010a). Th e six species of Dilkea subg. Dilkea have similar white fl owers and the useful morphological characters are mainly the position and structure of the infl orescence and the shape of the leaves and the fruits.
Woody climber, growth continuous, internodes subequal or gradually unequal, twigs drying brown to black; glabrous throughout. Stipules not seen. Leaf: petiole terete, reduced to the pulvinus, 3-6 mm long, swollen but not wrinkled when dry, drying nearly black; blades coriaceous, narrowly elliptic to oblanceolate, widest ca. 2/3 from base, 7.5-19 × 3.5-6.5 cm, base usually slightly acute, angle ca. 45° each side of the midrib, apex acute or round and short-acuminate, margin undulated on herbarium specimens, probably due to dorsiventrally curved midrib, adaxially dull, drying dark olive-green, abaxially dull, drying pale olive-green, midrib adaxially in a groove, abaxially strongly raised, main veins obscure, 15-20 on each side of the midrib of well-developed leaves. Infl orescences axillary; peduncle axillary, thicker than the stem, bearing 1-2 fl owers; bracts thick scale-shaped, 0.5-2 mm long, long and narrow to short and wide under the same fruit; pedicel and peduncle forming a narrow cone 0.5-1.5 cm long, 0.4-0.6 cm diam. at apex under the fruit. Flowers not seen. Fruits subterminal by withering of the apical part of the stem, spherical, observed still green but well-developed, fruit wall hard, 4-5 mm thick, corky, with 1-2 seeds, partly empty with at least partially dividing membranes; seeds peanut-shaped, slightly asymmetric, 1.7 × 0.7-0.8 cm.
Distribution. Endemic to the district of Iquitos, Maynas, Loreto, Eastern Peru. Th e specimen labels did not give geographical coordinates for the collection localities of Dilkea hebes in Peru, Loreto, Maynas, Distr. Iquitos. Th e localities cited for the two specimens, "quebrada de Morropón" or "Pampa Chica", are not in the gazetteer published by the United States Board on Geographic Names (USBGN 1989), and Santa Clara and Bella Vista are common village names in Peru. A search in the National Geospatial-Intelligence Agency database (NGA web site) on Santa Clara brought 11 occurrences in Loreto and Bella Vista / Bellavista 16. Coordinates for those are too uncertain to be presented in the specimen citations, but it is possible that they are Puerto Bellavista Nanay, port of Iquitos on the Río Nanay, ca. 3°42'S, 73°15'W, and Santa Clara de Nanay, near the far end of Iquitos airport on the bank of the Río Nanay, ca. 3°47'S, 73°20'W.
Ecology. Dilkea hebes is growing in inundated riparian forest, known only from the vicinity of the type locality, ca. 90 m elev.
Phenology. Fruits immature when collected in February and June. Preliminary conservation status. Dilkea hebes is known from two collections from the same district in Maynas, Loreto, Peru. Th e data are insuffi cient to assess an informed status for this species, therefore I suggest that it be classifi ed as DD (Data Defi cient) according to IUCN (2001IUCN ( , 2003 categories. Discussion. Dilkea hebes has a few fruit characteristics that distinguish it from all other species of Dilkea and that may be related to its frequently inundated habitat. Th e thick corky fruit wall, the small number of seeds leaving empty space in the fruit, and possibly the thin membranes inside the fruit increase the fl oatability of the fruit suggesting that the fruits may be disseminated during fl oods. Cork has been found in some species of Passifl ora, for example on the bark of mature stems of P. suberosa L. and Etymology. Th e Latin epithet hebes (= dull), refers to the upper surface of the leaves that is not shiny, in contrast with Dilkea nitens Feuillet, another species from Loreto described below.
Distribution. Dilkea nitens is known only by the type collection from Loreto (Peru). Th e geographical coordinates are taken from a gazetteer (USBGN 1989).
Ecology. Th e label does not give any information about the habitat. Phenology. It had immature fruits in August. Preliminary conservation status. Dilkea nitens is only known from the type collection from Maynas, Loreto, Peru. Th e data are insuffi cient to assess an informed status for this species, therefore I suggest that it be classifi ed as DD (Data Defi cient) according to IUCN (2001IUCN ( , 2003 categories. Discussion. In subgenus Dilkea where most species have oblanceolate to obovate leaf blades, D. nitens is clearly identifi ed by its narrowly ovate leaf blades, widest a quarter of the length from the base or less, a character shared only with D. margaritae Cervi from Mato Grosso (Brazil) which, in contrast with D. nitens, is a low shrub with 3.5-7 cm long axillary pedicels.
Etymology. Th e epithet coming from the Latin adjective nitens (= shiny), refers to the upper surface of the leaves, in contrast with Dilkea hebes, another species from Loreto described above.  Th e correct identifi cation for this collection is D. tillettii, as could be easily checked by looking at the scan of the specimen on the AAU web site.