Abstract Detail

Developmental and Structural Section

Mickle, James [1], Barone Lumaga, Maria Rosaria [2], Moretti, Aldo [3], De Luca, Paolo [4].

Systematic Implications of Cuticular Micromorphology in Cycas (Cycadales).

The genus Cycas is peculiar among cycads in lacking seed cones. Based on morphological and fossil evidence, it is considered to be the most primitive of the living cycad genera. Recent molecular studies have confirmed the basal phylogenetic position of the genus Cycas but taxonomic delimitation within the genus is still uncertain. The number of reported species range from the first enumeration of 8 species up to the 102 species and 8 subspecies plus other entities presently recognized. Taxonomic characters currently used in Cycas species delimitation emphasize macro-morphological characters such as size of the leaves and leaflets, height of the trunk, and morphology of the sporophylls. The present study looks at cuticle features studied by scanning electron microscopy (SEM). The aim is to compare the coherence of leaf micromorphology and molecular phylogeny with increasingly available data useful in clarifying unresolved affinities among species some weakly separated in the genus Cycas. SEM micromorphology shows similarities between C. revoluta and C. taituingensis, including organization of the stomatal complex and orientation of the stomata, but with differences in the number of epidermal cell that separate the stomatal complex, thus not supporting the synonymy proposed in recent literature. In the clade including C. circinalis, C. media and C. rumphii the latter species shows some similarities with C. debaoensis and C. szuchunensis. Cycas szechunensis and C. fairylakea appear to be very similar in micromorphological characteristics; together with C. debaoensis they have epidermal cells more elongate then C. revoluta and C. taitungensis or members of the C. media, C. rumphii, C. circinalis clade. The micromorphological similarities fit well with the distribution of the studied species: C. debaoensis, C. szuchunensis (C. fairylakea), C. revoluta, and C. taituingensis and all from East Asia; C. circinalis, C. media and C. rumphii and from India, Southeast Asia and Australia. While subtle, these micromorphological differences suggest a further mechanism for providing useful information in differentiating species among species of cycads, and in particular, the genus Cycas.

Broader Impacts:

1 - North Carolina State University, Department of Plant Biology, Campus Box 7612, 2115 Gardner Hall, Raleigh, NC, 27695-7612, USA
2 - ORTO BOTANICO, VIA FORIA 223, NAPOLI, I-80139, Italy
3 - DIPT DI BIOLOGIA VEGETALE, VIA FORIA 223, NAPOLI, I-80139, Italy
4 - Universita' di Napoli, Orto Botanico, via Foria, 223, Napoli, 80139, Italy

Keywords:
cycad
Cycas
Cycadales
cuticular micromorphology.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Grand Salon A - D/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 5:30 PM
Number: PDS015
Abstract ID:608
Candidate for Awards:None