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Diplotheca costata Valkanov, 1970. The lorica is composed of two quite distinct chambers. The anterior chamber contains 18 longitudinal costae, each being formed by two costal strips with spatulate ends. A transverse costa containing six flattened costal strips forms the anterior ring and another composed of crescentic strips marks the boundary between the two chambers. The posterior chamber contains 10 broad and flattened costal strips with rounded ends. Each strip has a more opaque central region, on either side of which is a thinner region bearing a row of narrow transverse markings.

Cosmoeca ventricosa Thomsen in Thomsen and Boonruang, 1984. Cells solitary. Cell body when dried 6.7-7.5 x 2.5-4 microns, flagellum about 20 microns long. Lorica barrel-shaped, 23-31 microns high, composed of3 transverse costae and 9-12 longitudinal costae. The two almost equally sized anterior transverse costae (average widths 22.4 microns and 19.2 microns) are located at the anterior end of the lorica chamber and at the level of the joints between the second and the third longitudinal costal strip (counted from the anterior lorica end). The number of strips in both anterior transverse costae corresponds to the number of longitudinal costae. The third minute transverse costa is formed by 3-4 costal strips and located at the level of the joints between the third and the fourth longitudinal costal strip (counted from the anterior lorica end). A numerical reduction in the number of longitudinal costae occurs below the posterior transverse costa.

Salpingoeca huxleyi Ellis, 1930. Cell globular. Body of lorica egg-shaped, with a wide, sturdy neck which bulges towards its own base. This neck appears to be marked off, at its actual base, from the lorica proper by a costa-like ring. This ring is probably an optical effect due to the lorica neck being set in a shallow depression or in-fold of the lorica body. A further peculiarity is that the neck of the cell is never extended beyond the distal limit of the lorica neck, so that the base of the collar is always within its everted rim. Collar and flagellum normal. Nucleus conspicuous. Contractile vacuoles: two. Peduncle length variable. Length of body of lorica: 8 microns Length of neck of loriea: 4 microns Width at centre of neck of lorica: 3 microns Greatest width of lorica: 6.5 microns Peduncle length: 16-32 microns

Syndetophyllum pulchellum (Leadbeater, 1974) Thomsen and Moestrup, 1983. Cell obovoid, 2 - 5 microns long x 2 - 4 microns wide, single flagellum approximately 15 microns long, funnel-shaped collar of approximately 20 tentacles 2 - 5 microns long. Lorica 6-8 microns high composed of two chambers. Anterior chamber consisting of 10 longitudinal costae and two transverse cos tae, one forming the anterior ring and one at the base of the chamber. Lower chamber formed by 10 longimdinal costae converging posteriorly. All costal strips forming the lorica broad with a thickened midrib with an elaborate pattern of perforations either side, costal strips of the anterior ring bearing an upright spine at one end.

Calliacantha frigida Thomsen, Garrison and Kosman, 1997. Choanoflagellates cells which occur as individuals. The cell body is about 4 x 8 microns long, with a pointed posterior end. The single flagellum (about 30 microns) is surrounded by a ring of tentacles that form the collar. The conical lorica chamber (10 - 14 microns long) consists of 2 transverse costae and 6 (7) longitudinal costae. The transverse costae (diameter about 5 and 4 microns respectively) are closely spaced (1 - 2 microns) at the anterior chamber end. Six rather short costal strips (about 4 microns) form part of the anterior transverse costa, whereas the posterior transverse costa appears to consist of fewer costal strips. Anterior transverse and longitudinal costal strips form E-joins. Each longitudinal costa is composed of two costal strips, each 6 - 8.5 microns long. The costae continue above the anterior transverse costa forming projections that become narrower and are about one costal strip in length (about 9.5 - 12.5 microns). The projections in the living cell lie almost perpendicular to the longitudinal axis of the lorica. The number of longitudinal costae is less towards the hind end of the lorica chamber due to the amalgamation in pairs and threes of costal strips. The lorica is terminated by an aggregated pedicel formed of 3-5 bundled costal strips are each 7 - 9.5 microns long. They have swollen and clawed posterior tips and they often diverge to form a larger holdfast area. A protoplast suspensory membrane extends from the base of the lorica chamber to the level of the posteriormost transverse costa. Replication tectiform.

Codonocladium cymosum (Kent, 1880) Boucaud-Camou, 1967. Cells symmetrically ovate, located on short independent stalks, at the ends of a branching stalk-system, cells 5 microns long, main stalks 51-102 microns

Desmarella moniliformis Kent, 1880. Cells 6.4 microns, symmetrically ovoid, arranged in single chain-like series, each colony containing from two to as many as eight individuals, nucleus spherical, subcentral, two or more contractile vacuoles, posteriorly located.

In vivo portrait of the colonial choanoflagellate, Desmarella moniliformis (Kent,1878). Ovoid cells are joined at lateral surfaces foming linear or slightly crescentic colonies.Cells have single anterior apical flagellum surronded by a collar of microvilli.Cells lack a pedicel.Collected near Boise, Idaho (43°38'21.10"N 116°11'10.78"W elev. 2908 ft.) from an ice-covered temporary puddle containing leaf litter and dead grass.November, 2005.Phase contrast.

In vivo portrait of the colonial choanoflagellate, Desmarella moniliformis (Kent,1878). Ovoid cells are joined at lateral surfaces foming linear or slightly crescentic colonies.Cells have single anterior apical flagellum surronded by a collar of microvilli.Cells lack a pedicel.Collected near Boise, Idaho (43°38'21.10"N 116°11'10.78"W elev. 2908 ft.) from an ice-covered temporary puddle containing leaf litter and dead grass.November, 2005.DIC.

Monosiga (mono-sigh-ga) a naked choanoflagellate (collar-flagellate). The cell body is small - about 5 microns. A single flagellum projects from the anterior end. It is surrounded by a collar of fine pseudopodia. Beating of the flagellum draws a current of water through the collar and particles of food are trapped against the collar. Pseudopodia can then enclose the food so that it can be digested. Animations by Rosemary Arbur of flagellar beat patterns are available here. Phase contrast.

Monosiga (mono-sigh-ga) a naked choanoflagellate (collar-flagellate). The cell body is small - about 5 microns A single flagellum projects from the anterior end. It is surrounded by a collar of fine pseudopodia. Beating of the flagellum draws a current of water through the collar and particles of food are trapped against the collar. Pseudopodia can then enclose the food so that it can be digested. Animations by Rosemary Arbur of flagellar beat patterns are available here. Phase contrast.

Monosiga (mon-owe-sigh-ga), a choanoflagellate (collar flagellate), here many cells have colonised a small piece of detritus. Each globular cell has a conical collar around the single apical flagellum. Phase contrast.

Portrait of Monosiga, a choanoflagellate without a visible lorica. A collar of pseudopodia which trap food particles surrounds a central flagellum. The particles are transported to the base of the collar where they are ingested. This is an unusually large specimen. The cell body is usually about 5 microns in length. The nucleus, food vacuoles and contractile vacuole are well seen here. This species is stalked while others are not, the cell body attaching directly to the substrate. From a freshwater pond near Boise, Idaho. Phase contrast.

Monosiga ovata Kent, 1880. The ovoid cell is approximately 4 microns long or 15 microns when measured from the tip of the flagellum to the distal end of the stalk. At the anterior end of the cell a ring of 20-25 tentacles, almost equal in length, forms a collar which encircles the single flagellum. The latter projects beyond the tentacles and terminates in a conspicuous hair point. The cell body and the base of the tentacles are closely invested by a delicate membranous sheath and this tapers posteriorly to form the stalk or peduncle which attaches the cell to the substratum. The apparent looseness of the sheath in shadowcast whole mounts is probably caused by the shrinkage of the protoplast during drying. Transverse sections of the cell in the region of the tentacles and cell body show that the sheath fits closely although it is ridged at intervals. That part forming the stalk sometimes has a fibrillar appearance but it is not clear whether this is a partial disintegration caused by drying or a genuine arrangement for attaching the cell to the substratum. In section the sheath is seen to be composed of two regularly spaced layers, the surfaces of which are covered with a fine fibrillar deposit possibly of mucilage.

Monosiga brevicollis Ruinen, 1938. The shape of the cells is variable. The resting cells are 4-6 microns long, more or less spherical. When swimming, the posterior end is sharpened, the shape becomes more ovoid and the collar is spread out. The collar is 0.5 cell length, the flagellum about 4.5. cell length. The cytoplasm is fine-grained to hyaline and contains strongly refractile grains. A vacuole lies in the posterior part of the cell.

PRESS RELEASE  Can you hear me now? Primitive microbe bests human in complexity of cell communication genes July 08, 2008 LA JOLLA, CA   When it comes to cellular communication networks, a primitive singlecelled microbe that answers to the name of Monosiga brevicollis has a leg up on animals composed of billions of cells. It commands a signaling network more elaborate and diverse than found in any multicellular organism higher up on the evolutionary tree, researchers at the Salk Institute for Biological Studies have discovered. Their study, published during the week of July 7-11 in the online edition of the Proceedings of the National Academy of Science, unearthed the remarkable count of 128 tyrosine kinase genes, 38 more than found in humans. These kinases transmit essential signals for cell growth, stasis, and death. Though their activity is tightly regulated in normal cells, out-of-control kinases are a major cause of cancer. Many successful cancer drugs – such as Gleevec, which is used for the treatment of leukemia, – specifically target wayward tyrosine kinases. This treasure trove of diverse and novel tyrosine kinases took the lead author of the study, Gerard Manning, who heads the Razavi-Newman Center for Bioinformatics, by surprise since it was long thought that tyrosine kinases are restricted to multicellular animals where they handle communication between cells. Manning says that they were absolutely stunned,based on past work, we had expected maybe a handful of these kinases but instead discovered that this primitive organism has a record number of them. Two other essential parts of the tyrosine kinase network – PTP and SH2 genes – are also more numerous than in any other genome, showing that it is the whole network that is elaborated here.   The 100 trillion cells in our bodies require elaborate communication systems to coordinating their activities. Tyrosine kinases, extremely well-studied enzymes that act as receivers for external cues such as a growth signals and relay their message within cells by attaching tiny phosphate groups to proteins, are a vital part or this communication system.  At first glance, Monosiga brevicollis, which belongs to the group of choanoflagellates – microscopic, aquatic organisms that occupy the grey area between fungal and animal kingdoms – has little in common with multicellular animals that need to co-ordinate the activities of billions of cells. But its distinctive architecture – a collar of tentacle surrounding a whip-like tail known as flagellum – has the same basic structure as collar cells that aggregate to form sponges, which are considered the most primitive multicellular organisms or metazoans. Because of their key evolutionary position, M. brevicollis was selected as a representative choanoflagellate for whole genome sequencing. Choanoflagellates are like the first cousins of animals and their genome allows us a glimpse into the evolutionary origin of animals - says Manning. The Monosiga kinases are more divergent than anything previously seen in animals, which may help scientists understand the fundamentals of how all tyrosine kinase signaling works. Despite their extreme diversity, Monosiga kinases time and again arrive at the same solution to a problem, as do animal kinases, but using a distinct method for instance to create a sensor structure that emerges from the cell, or to target a kinase to a specific part of the cell. Manning says that this convergent evolution suggests that there are only a limited number of ways build a functional network from these components. With all this new information, one obvious question remains unanswered: what is a singlecelled organism doing with all this communications gear? Manning says: - We do not have a clue!, but this discovery is the first step in finding out.  For more information  Researchers who also contributed to the work include Yufeng Zhai, Ph.D. from the Salk Institute, Susan L. Young, Ph.D., in the Center for Integrative Genomics at the University of California, Berkeley and W. Todd Miller, Ph. D. in the Department of Physiology and Biophysics at Stony Brook University, Stony Brook.

Monosiga marina marina Paasche, 1961. We have not been able to obtain a description of this variety available at this time.

Monosiga marina minima Paasche, 1961. Cell body fusiform, length 4-8 microns, width about 2 microns Collar distally constricted, 2 microns long and equally wide. Typically without basal prolongation or stalk.

Proterospongia (pro-terr-ow-sponge-ee-a) a collar flagellate (choanoflagellate), normally regarded as forming flat colonised, but in culture the capacity to form colonies can be lost, to leave cells indistinguishable from the solitary Monosiga. With apical flagellum and a collar, only the edge of which is seen as a dark line on either side of the flagellum. Phase contrast.

Detail of Sphaeroeca volvox showing individual cells with a single anterior emergent flagellum with surrounding collar of microvilli. Posteriorly the cells are drawn out into a long thread-like process, which may adhere to those of other cells in the center of the spherical colony. From temporary rainwater pool near Boise, Idaho. Brightfield illumination.

Portrait of colorless, motile, colonial choanoflagellate, Sphaeroeca volvox. Individual cells have no visible periplast by light microscopy. Cell shape is approximately pyriform. There is one anterior emergent flagellum with a short circumferential collar of microvilli. The posterior end of the cell is drawn out into a long thread, which may join with those of other cells. Spherical colonies are composed of large numbers of cells. From temporary rainwater pool near Boise, Idaho. DIC.

Sphaeroeca are colonial choanoflagellates, with a pyriform or ovoid cell bearing one long flagellum arising from a collar and a pointed posterior end. Cells are arranged on surface of a sphere with flagella directed outwards. Sphaeroeca volvox Lauterborn forms spherical colonies 250-500 microns diameter, individual cells 5-6 microns long and flagellum 36-40 microns long, contractile vacuoles at the posterior end. Planktonic in freshwater habitats.