Phacus multifacies sp . nov . , a new Euglenophyceae from the State of Rio Grande do Sul , Southern Brazil

(Phacus multifacies sp. nov., a new Euglenophyceae from the State of Rio Grande do Sul, Southern Brazil). As a result of the taxonomic survey of the pigmented Euglenophyceae of Lago da Ponte, an artifi cial pond located at the Porto Alegre Botanical Garden, State of Rio Grande do Sul, Southern Brazil and samples gathered later on from this same water body, a new species of Phacus (Euglenophyceae, Phacaceae), P. multifacies Alves-da-Silva & C. Bicudo, sp. nov., is here described and proposed as new to science. Cell displacement turning ventrally one full turn round itself and also rotating around its longitudinal axis and the presence of a dorsal wing-like expansion next to the caudal process are the main diagnostic features of the new species. Physical and chemical information on the pond water is presented.

Most Phacus species are euplanktonic, occurring together with species of other Euglenid genera (mainly Euglena, Lepocinclis and Trachelomonas), and certain species are capable of surviving high nutrient concentrations.Unlike Euglena and Trachelomonas, Phacus rarely becomes a major component of phytoplankton communities (Weik 1967).Its representative individuals are unicellular and freeswimming due to the presence of two fl agella, from which just one emerges from the reservoir.The cell is naked, i.e. do not have a cell wall, but a rigid pellicle with longitudinal or helicoidal striae; cell is dorsiventrally fl attened, has the shape variable between fusiform and ovate, but some have wing like projections and the posterior pole with a caudal process of variable length depending on the species.Vertical view may be elliptic, sausage-shaped, somewhat triangular or triradiate.
Paper is a result of the taxonomic survey of the

Material and methods
The Porto Alegre Botanical Garden is located at 30°03'05"S and 51°10'34"W, covers an area of ca.39 ha, and includes two artificial ponds.The one presently studied is locally known as Lago da Ponte, but it was a wetland before conversion into a pond in 2003 after removal of the grass-like vegetation and addition of water.Building of the pond aimed only at landscaping composition.Presently, the pond is very much anthropized and mainly maintained by rain water.Its surface is at present covered with Salvinia sp.Fish (grass carps), black swans, turtles and terrapins are the pond main inhabitants.
Monthly sampling was performed between July 2007 and June 2008 in two opposite stations located at the pond margin, and later on at a daily basis between 12 and 15 and 18 and 19 January 2010 only at station 1 using a 25 mm mesh plankton net.After collection, samples were immediately fixed and preserved with 4% formaldehyde water solution.Water and air temperature, pH (pHmeter DMPH-P), sampling stations depth, water transparency (Secchi disk), and electric conductivity (conductivimeter Digimed, model CD-28) were measured 'in situ'; dissolved oxygen, percentage of dissolved oxygen and amount of organic matter in the water were measured in the laboratory using APHA (2005) methods.Analysis of biological material was performed between slide and cover slip using both live and preserved material under a Leica-DMLS optical microscope furnished with micrometer ocular.Illustrations were prepared with the help of a camera-lucida coupled to the microscope optical system, and the photomicrographs were taken with a Sony digital camera also coupled to the microscope (Alves-da-Silva et al. 2011).
Although molecular studies with this new species material have not been carried out, their morphological characteristics and a distinct displacement way constitute the base for this proposal.Also, worth mentioning is that approximately 80 individuals were found in the 12 sample units studied.
The present new species shows a broad spectrum of cell form variation depending on which position the cell is observed.In lateral view, P. multifacies sp.nov.could be somewhat confused with P. raciborskii Drezepolski, since it may also be lunate or show a torsion at the anterior pole (figura 9).In lateral (taxonomic) view it is, however, very much different, since it is obtriangular (figuras 11, 16-17) to slightly ovate (figuras 1, 3, 10).Other striking characteristics of P. multifacies sp.nov.are: (1) its comparatively small cell dimensions, (2) the very rapid locomotion, (3) the two centrally located concentric paramylum granules, and a third one eccentric, posterior or laterally placed regarding the central ones, (4) some specimens show a dorsal wing-like expansion next to the caudal process (figuras 5, 7, 24), and (5) the kind of cell displacement turning ventrally one full turn round itself (figuras 9, 27) and also rotating round its longitudinal axis.

Ecological remarks
A somewhat large number of individual specimens of the diatoms Aulacoseira granulata (Ehrenberg) Simonsen and Aulacoseira ambigua (Grunow) Simonsen and of the dinoflagellate Peridinium gatunense Nygaard were observed in every preparation from Lago da Ponte analyzed along the entire study period.
The pond is a very shallow system, station 1 being a little deeper (maximum depth 1 m, average depth 0.54 m) than station 2 (maximum depth 0.3 m, average depth 0.22 m).Individual specimens of P. multifacies were collected from depths ranging from 0.13 m to 0.35 m, i.e. always from very shallow totally transparent environments.