Miconia rivalis Wurdack
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Authority
Wurdack, John J. 1967. Plants collected in Ecuador by W. H. Camp. Melastomataceae. Mem. New York Bot. Gard. 16: 1-45.
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Family
Melastomataceae
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Scientific Name
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Description
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Latin Diagnosis - Sect. Miconia. M. microcarpae DC. et M. affini DC. affinis, sed foliis propor-tionaliter latioribus ramulorum nodis non carinatis. Ramuli primum quadrisulcati demum teretes vel compresso-teretes sicut petioli foliorum venae primariae subtus inflorescentia hypanthiaque primum dense indumento appresso amorpho-stellulato obsiti demum glabrati. Petioli (1.5-) 3-5 cm; lamina (10-) 15—30 x (4.5-) 11-20 cm chartacea vel rigidiuscula elliptico-ovata apice hebeti-acuto vel graclatim breviterque per 1-2 cm hebeti-acuminato basi rotundato-truncata vel paulo (0.7-1.7 cm) cordata, undulato-serrulato dentibus 2-3 mm inter se distantibus et (0.1-) 0.5-1 mm profundis, 5-nervata (pare inframarginali debili neglecto) nervis secundan is 3-8 mm inter se distantibus tertiariis non vel laxe reticulatis et supra plerumque obsoletis, supra glabra, subtus in venulis superficieque primum indumento amorpho-lepidoto obsita mox glabrata. Panicida 10-23 X 9-17 cm oblongo-pyramidata; flores 5-meri sessiles numerosi in ramulis brevibus conferti, bracteis bracteolisque 0.5-1 X 0.3-0.5 mm mox caducis. Hypanthium (ad torum) 1.7-2 mm; calycis tubus 0.3-0.5 mm altus, lobis interioribus 0.3-0.5 mm altis rotundato-cleltoicleis, dentibus exterioribus acutis lobos interiores aequantibus. Pétala glabra 1.8-2.3 X 1.1-1.4 mm obovato-oblonga apice oblique truncato vel paulo retuso. Stamina paulo anisomorphica glabra; filamenta 2-2.5 mm; antherarum thecae 1.4-2 mm longae oblongae ad apicem late ventraliterque uniporosae, connectivo sub loculis 0.1-0.3 mm prolongato dorsaliter ad basim minute (0.1 mm) hebeti-tuberculato ventraliter bilobulato lobulis hebetibus 0.2-0.3 mm longis. Stylus 4-4.5 X 0.3-0.5 mm glaber; stigma expansum 0.7-0.9 mm diam.; ovarium 3-loculare ½ inferum ca. 30-ovulatum apice conico glabro.
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Discussion
Type Collection: W H. Camp E-46 (holotype US 2404749; isotype NY), collected in the valley of the Río Zamora east of Loja, ca. 5 km downstream from Zamora, Prov. Santiago-Zamora, Ecuador, elev. 900 m, 28 June-1 July 1944. “Tree 8 m, also seen shrubby. Flowers white.’’ Paratypes (all Ecuador) : Napo-Pastaza: Tena, Asplund 8990 (S), Asplund 9002 (S), Mexia 7128. Santiago- Zamora: Macas, Asplund 19787 (S) ; Zamora-Cumbaraza, Harling 5880 (S) ; Río Paute, 2-3 km west of Mendez, Camp E-1482. Both suggested relatives have elliptic proportionately narrower leaf blades which are widest at or slightly above the middle, as well as interpetiolar ridges on the branchlets. I still have no firm opinion on the validity of the specific separation of these two taxa as suggested by Urban (Ark. Bot. 22A, 17: 33. 1929) and certainly vegetative criteria are dubious. Both M. egensis Cogn. and M. zubenetana Macbr. have coarser stem and inflorescence pubescence (very short pinoid hairs), with tufts of sparsely barbellate hairs (to 1 mm long) in the petiole axils at the junctions with the branchlets; perhaps these two are not specifically separable. Some of the collections of M. rivalis have somewhat the vegetative aspect of M. gibba Markgraf, but lack the petiolar appendages; also M. rivalis has much finer more appressed pubescence, leaf blades plane above and marginally with more distant and blunt teeth, and interior calyx teeth less developed. Miconia gibba has recently been collected (and identified ex descr.) topotypically (Asplund 18389, from the Río Negro on the shore of the Río Pastaza, elev. 1200 m, Napo-Pastaza, Ecuador); another collection is Asplund 8549 (S), from the Pastaza valley, between the Río Topo and La Victoria, elev. 1300 m. Miconia calvescens DC. and M. guayaquilensis (Bonpl.) D. Don also have the general facies of M. rivalis; both these species have more abundant almost flocculose inflorescence pubescence, larger bracts and flowers, and large stamens with cordi-form often gland-edged connective appendages.