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PHYLOGENETIC POSITION OF CRUSTOMASTIX STIGMATICA SP. NOV. AND DOLICHOMASTIX TENUILEPIS IN RELATION TO THE MAMIELLALES (PRASINOPHYCEAE, CHLOROPHYTA) 1
Author(s) -
Zingone Adriana,
Borra Marco,
Brunet Christophe,
Forlani Gandi,
Kooistra Wiebe H. C. F.,
Procaccini Gabriele
Publication year - 2002
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1046/j.1529-8817.2002.t01-1-02035.x
Subject(s) - biology , pyrenoid , botany , monophyly , molecular phylogenetics , clade , chlorophyta , phylogenetic tree , chloroplast , evolutionary biology , algae , genetics , gene
A new marine microalga from the Mediterranean Sea, Crustomastix stigmatica Zingone, is investigated by means of LM, SEM, TEM, and pigment and molecular analyses (nuclear‐encoded small subunit [SSU] rDNA and plastid‐encoded rbc L). Pigment and molecular information is also provided for the related species Dolichomastix tenuilepis Throndsen et Zingone. Crustomastix stigmatica has a bean‐shaped cell body 3–5 μm long and 1.5–2.8 μm wide, with two flagella four to five times the body length. The single chloroplast is pale yellow‐green, cup‐shaped, and lacks a pyrenoid. A small bright yellow stigma is located in the mid‐dorsal part of the cell under the chloroplast membrane. An additional accumulation of osmiophilic globules is at times seen in a chloroplast lobe. Cells lack flat scales, whereas three different types of hair‐like scales are present on the flagella. The main pigments of C. stigmatica are those typical of Mamiellales, though siphonein/siphonaxanthin replaces prasinoxanthin and uriolide is absent. The pigment pool of D. tenuilepis is more similar to that of Micromonas pusilla (Butcher) Manton et Parke and of other Mamiellales. The nuclear SSU rDNA phylogeny shows that the inclusion of C. stigmatica and D. tenuilepis in the Mamiellales retains monophyly for the order. The two species form a distinct clade, which is sister to a clade including all the other Mamiellales. Results of rbc L analyses failed to provide phylogenetic information at both the order and species level. No unique morphological or pigment characteristics circumscribe the mamiellalean clade as a whole nor its two daughter clades.