Saturday, June 9, 2018

[Botany • 2018] Pitcairnia robert-downsii • A Multivariate Analysis of the Pitcairnia palmeri group (Bromeliaceae: Pitcairnioideae)


Pitcairnia robert-downsii González-Rocha, Espejo, López-Ferr. & M. Castillo

in González-Rocha, Castillo-Rivera, López-Ferrari & Espejo-Serna, 2018.

Abstract

A multivariate analysis of the Pitcairnia palmeri group are presented. Principal Components and Cluster analyses were performed in order to have more accurate information to delimit the species. The analyses showed that the specimens referred to Pitcairnia palmeri var. longebracteata are clearly delimited, while those identified as P. palmeri var. palmeri, P. colimensis, and P. compostelae have a greater overlap of morphological characters, but remain as separate entities. A discriminant analysis showed that morphological characters used have significant multivariate differences between the taxa (P < 0.0005), and that the most important variables in the differentiation of these taxa are the percentage of floral bracts that exceeds the length of the sepals, the length of the floral bracts, and the length of the peduncle. We conclude that P. palmeri var. longebracteata is clearly a different species, not a variety, therefore is described and illustrated as Pitcairnia robert-downsii, and that P. palmeri, P. compostelae and P. colimensis maintain their taxonomic status.

Keywords: Durango, Pitcairnia, Monocots


FIGURE 4. Pitcairnia robert-downsii González-Rocha, Espejo, López-Ferr. & M. Castillo, nom. et stat. nov.

A–B) Detail of the inflorescence, C) habitat and D) dissected flower.

Pitcairnia robert-downsii 
González-Rocha, Espejo, López-Ferr. & M. Castillo, stat. et nom. nov. 

Pitcairnia palmeri var. longebracteata L.B. Sm., syn. nov., Wrightia 2: 64. 1960, 

Type: MEXICO. Durango: Municipio de Pueblo Nuevo, 15–17 miles northeast of Palmito along highway from Mazatlán to Durango, 7000–7500 ft, pine-oak forest, June 16, 1951 (fl), H.S. Gentry & C.L. Gilly 10625 (holotype LL!).

 The new species differs from Pitcairnia palmeri by its longer peduncle bracts (5.3‒11.2 cm long vs. 1.3‒8.6 cm), by the length of its floral bracts (1.5‒5.8 cm vs. 0.4‒2.8 cm), by its densely white-lepidote leaves (vs. scarcely lepidote), by the number of flowers per inflorescence (19‒30 vs. 3‒21) and by its polystichously (vs. secund) flowers.

....

Etymology:— The specific epithet honors the American botanist Robert Jack Downs (1923-2015), who, in collaboration with Lyman B. Smith, published the monograph of the Bromeliaceae for the Flora Neotropica. For his essential contribution to the studies in Bromeliaceae. 


Distribution, habitat and phenology:— Pitcairnia robert-downsii is only known from the state of Durango, in the municipality of Pueblo Nuevo (Fig. 5). It grows on cliffs or rocky slopes in pine-oak forests, at elevations between 1900 and 2500 m. It flowers from May to July.


  Edith González-Rocha, Manuel Arnoldo Castillo-Rivera, Ana Rosa López-Ferrari and Adolfo Espejo-Serna. 2018. A Multivariate Analysis of the Pitcairnia palmeri group (Bromeliaceae: Pitcairnioideae). Phytotaxa. 351(3); 219–228. DOI:  10.11646/phytotaxa.351.3.3

Resumen: Se presenta un análisis multivariado del grupo de Pitcairnia palmeri. Se realizaron análisis de componentes principales y de conglomerados con el propósito de obtener información más precisa para delimitar las especies. Dichos análisis mostraron que los especímenes referidos a Pitcairnia palmeri var. longebracteata están claramente delimitados, en tanto que los identificados como P. palmeri var. palmeriP. colimensis P. compostelae presentan una mayor superposición en sus caracteres morfológicos, aunque se mantienen como entidades separadas. Un análisis de discriminantes mostró que los caracteres morfológicos utilizados presentan diferencias significativas entre los taxa (P < 0.0005), y que las variables más importantes para diferenciarlos son el porcentaje de brácteas florales que sobrepasan el tamaño de los sépalos, el largo de las brácteas florales y el del pedúnculo. Se concluye que P. palmeri var. longebracteata es claramente una especie diferente, no una variedad, por lo que se describe e ilustra Pitcairnia robert-downsii y que P. palmeri, P. compostelae P. colimensis mantienen su estatus taxonómico. 
Palabras clave: Durango, Pitcairnia

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