A New Species of Myrcia (Myrtaceae) for Panama

Abstract

Myrcia fosteri (Myrtaceae) is described as new. The species is closest to M. fallax (Rich.) DC. but differs in having smaller flowers, more prominently acuminate leaf blades and fruits which are globose to depressed-globose. For a number of years a population of Myrcia (Myrtaceae) on Barro Colorado Island was observed by both myself and by Robin Foster, then a resident of the island. Plants collected over a period of several years were tentatively identified as Myrcia gatunensis Standley following Amshoff's treatient in the Flora of Panama (1958: 172-175). The species is closely related to and perhaps inseparable from M. fallax (Rich.) DC. After several years of field observations as well as herbarium and library studies, it is concluded that this Myrcia is a new species. Arbor parva 3-8 m; laminae lanceolatae ad ellipticae, abrupte caudatae-acuminatae, acutatae ad basim, 3-8 cm longae, 1-3(-3.5) cm latae; inflorescentiae racemos vel paniculas axillares 1-2.5 cm longos formantes; alabastra 1.5-2 mm longa; bacca globosa vel depressaglobosa, circa 5 mm longa, 6-8 mm diametro. M. fallax (Rich.) DC. maxime simile sed ab hac specie differt floribus parvioribus, laminis plus abrupte acuminatis, et bassis globosis ad depressis-globosis. Slender tree 3-8 m tall; trunk to ca. 7 cm dbh. Leaves opposite; petiole 2-6 mm long, sparsely to densely ? appressed-pubescent with short brownish trichomes; blade lanceolate to elliptic, abruptly caudate-acuminate, acute (rarely obtuse) at base, 3-8(-10) cm long, 1-3(-3.5) cm wide, lower surface inconspicuously pubescent throughout, the trichomes denser on midrib above and below, glabrescent above except midrib, pellucid-punctate, thin, the secondary veins not prominulous below on drying, the acumen often as much as 1/4 the length of the blade, the margin entire and + revolute especially near base. Flowers 5-parted, in axillary racemes or panicles 1-2.5 cm long; pedicels 1-1.5 mm long; buds 1.5-2 mm long; calyx to ca. 2.5 cm wide, the lobes short-triangular to rounded; axes of inflorescence, pedicels and hypanthium densely, erect to more commonly appressed-pubescent; petals orbicular, ca. 1.7 mm long, pellucid-punctate, white, soon falling; stamens numerous, to 3.5 mm long; ovary and lower half of style short-villous; ovary and style together to 5.5 mm long. Berry globose to depressed-globose, 6-8 in diameter, to ca. 5 mm long, turning blue-gray, finally blue-black at maturity; seed 1, + globose, ca. 4 mm in diameter, smooth; seed coat thin, brown. Holotype: Croat 15147 (MO, 2059366); isotypes CAS, COL, DUKE, F, GH, K,