HOOPS HJ, LONG JJ, HILE ES

FLAGELLAR APPARATUS STRUCTURE IS SIMILAR BUT NOT IDENTICAL IN VOLVULINA-STEINII, EUDORINA-ELEGANS, AND PLEODORINA-ILLINOISENSIS (CHLOROPHYTA) - IMPLICATIONS FOR THE VOLVOCINE EVOLUTIONARY LINEAGE
J PHYCOL 30 (4): 679-689 AUG 1994

Abstract:
The colonial and multicellular members of the Volvocales can be arranged in order of increasing size and complexity as the ''volvocine series.'' This series is often assumed to reflect an evolutionary progression. The flagellar apparatuses of previously examined algae are not consistent with a simple lineage. The flagellar apparatuses of Astrephomene gubernaculifera Pocock, Gonium pectorale Muller, Platydorina caudata Kofoid, Volvox rousseletii G. S. West, and V. carteri f. weismannia (Powers) Iyengar differ from one another, and there is no apparent progression in flagellar apparatus features from the simple to complex colonial forms. We examined the flagellar apparatuses of Volvulina steinii Playfair, Eudorina elegans Ehr., and Pleodorina illinoisensis Kofoid and found then to be similar to one another. The basal bodies ave connected by a distal fiber that is offset to the anti side of the cell. Two microtubular rootlets originate on the inside of the basal bodies and extend toward the syn side. The other two rootlets are oriented perpendicular to the first two and are anti-parallel to each other. A coarsely striated component underlies the four-membered rootlets and extends to the basal bodies. A proximal fiber complex connects the two basal bodies. This complex consists of a branched striated component on the cis side of each basal body. One part extends toward the anti side of the cell, while the other extends into a fibrous component that runs between basal bodies. An additional structure extends in the anti direction from the trans side of each basal body. A fibrous component extends past one basal body in all four species. This component goes past the trans basal body in Volvulina steinii and the cis basal body in E. elegans and P. illinoisensis. The flagellar apparatuses of these organisms are similar to those of G. pectorale and Volvox carteri but different from the other colonial volvocalean algae examined. The algae examined in this study plus G. pectorale and V. carteri probably share a common evolutionary history that postdates the transition from the unicellular to colonial habit. Such a shared evolutionary history is a requirement of the volvocine hypothesis. However, we have not observed progressive changes in the flagellar apparatus correlated with increasing cell number, differentiation, and sexual specialization. Thus, it is possible, but not certain, that G. pectorale, Volvulina steinii, E. elegans, P. illinoisensis, and Volvox carteri may form part of a volvocine lineage.

NOZAKI H, AIZAWA K, WATANABE MM

A TAXONOMIC STUDY OF 4 SPECIES OF CARTERIA (VOLVOCALES, CHLOROPHYTA) WITH CRUCIATE ANTERIOR PAPILLAE, BASED ON CULTURED MATERIAL
PHYCOLOGIA 33 (4): 239-247 JUL 1994

Abstract:
The taxonomy of four species of Carteria with cruciate anterior papilla (Volvocales, Chlorophyta) was studied in two strains isolated recently from Japan, four UTEX and five Japanese NIES strains. Light and scanning electron microscopy demonstrated that the papillae of all strains were pentagonal in side view and exhibited four ridges twisting counterclockwise in top view. The strains were clearly delineated into four species, C. crucifera Korshikov ex Pascher, C. eugametos Mitra, C. inversa (Korshikov) Bourrelly and C. cerasiformis Nozaki, Aizawa et M.M. Watanabe sp. nov., based on differences in cell shape, position of the nucleus, form of the stigma, structure of the anterior papilla and pyrenoid, as well as the mode of cell division during asexual reproduction. The taxonomic conclusion of Fott (1968) who synonymized C. eugametos with C. lunzensis Pascher et Jahoda, is rejected after re-examination of the type strain of C. eugametos.

NOZAKI H, ITOH M

PHYLOGENETIC-RELATIONSHIPS WITHIN THE COLONIAL VOLVOCALES (CHLOROPHYTA) INFERRED FROM CLADISTIC-ANALYSIS BASED ON MORPHOLOGICAL DATA
J PHYCOL 30 (2): 353-365 APR 1994

Abstract:
A cladistic analysis was used to deduce the phylogenetic relationships within the colonial Volvocales. Forty-one pairs of characters related to gross morphology and ultrastructure of vegetative colonies as well as asexual and sexual reproduction were analyzed based on parsimony, using the PAUP 3.0 computer program, for 25 species belonging to nine volvocacean and goniacean genera of the colonial Volvocales. Chlamydomonas reinhardtii Dangeard was the outgroup. The strict consensus tree indicated the presence of two monophyletic groups, one composed of all the volvocacean species analyzed in this study and the other containing the goniacean species except for the four-celled species Gonium sociale (Dujardin) Warming. In addition, these two groups constitute a large monophyletic group, to which G. sociale is a sister group. A new combination Tetrabaena socialis (Dujardin) Nozaki et Itoh and a new family Tetrabaenaceae Nozaki et Itoh are thus proposed for G. sociale. In addition, the analysis suggests that the volvocacean genera Eudorina and Pleodorina are paraphyletic groups, respectively, and that the monotypic genus Yamagishiella has no autapomorphic characters and represents primitive features of the anisogamous and oogamous genera of the Volvocaceae. Phylogenetic relationships within the Volvocaceae and the Goniaceae, as well as the various modes of sexual reproduction exhibited by these organisms, are discussed on the basis of the analysis.