Acanthoecida

Polyoeca dichotoma Kent, 1880. Lorica of polythecium urceolate, pedicellate, tapering posterioly, slightly constricted at a distance of one-third of the total length from the anterior margin, and then widening out to their greatest diameter, pediceles of each separate lorica straight, slender, varying from the same to two or three times the length of the latter structure, contained animalcules ovate, occupying respectively about one-half of the cavities of the lorica, contour of polythecium subdichotomous, each zooid usually giving rise by trasverse fission to two new ones which attach themselves to opposite sides of the parent lorica. Length of separate lorica 10 microns

Portrait of the acanthoecid choanoflagellate, Polyoeca dichotoma (Kent, 1881).  Cells are solitary or united to form linear or dendroid colonies which attach to the substrate. The lorica is funnel-shaped, constructed of numerous siliceous longitudinal costae, each made up of costal strips. The longitudinal costae terminate as anterior spines (11-17); 2 or more bands of equally spaced transverse costal strips (difficult to see in vivo) encircle the lorica chamber in which the protoplast (cell body) resides. At the apex of the funnel the longitudinal costae unite to form an aggregated pedicel. In dendroid colonies the pedicel of the daughter (anterior) cell attaches to the outside of the lorica of the parent cell. Details of lorica morphology are best seen with scanning electron microscopy. The cell body has one anterior flagellum (seen here) surrounded by a rhizopodial collar (not visible here). Division is nudiform (i.e. naked swarmers are formed which then form a lorica). Collected from a commercial saltwater aquarium in Boise, Idaho February 2004. DIC. 

Portrait of the acanthoecid choanoflagellate, Polyoeca dichotoma (Kent, 1881).  Cells are solitary or united to form linear or dendroid colonies which attach to the substrate. The lorica is funnel-shaped, constructed of numerous siliceous longitudinal costae, each made up of costal strips. The longitudinal costae terminate as anterior spines (11-17); 2 or more bands of equally spaced transverse costal strips (difficult to see in vivo) encircle the lorica chamber in which the protoplast (cell body) resides. At the apex of the funnel the longitudinal costae unite to form an aggregated pedicel. In dendroid colonies the pedicel of the daughter (anterior) cell attaches to the outside of the lorica of the parent cell. Details of lorica morphology are best seen with scanning electron microscopy. The cell body has one anterior flagellum (seen here) surrounded by a rhizopodial collar (not visible here). Division is nudiform (i.e. naked swarmers are formed which then form a lorica). Collected from a commercial saltwater aquarium in Boise, Idaho February 2004. DIC. 

Saepicula (see-pick-you-la) pulchra Leadbeater, 1980. Cell body is about 4 - 6 microns long. The flagellum is about 1.5 times the cell body and its tip is thin. The lorica consists of several transverse costae and 10 longitudinal costae. The anterior of the lorica is everted and the posterior of the lorica is conical. The anterior end of the lorica is surmounted by a single transverse costal band, which is connected to the longitudinal costae, and the lower part composes of several transverse and longitudinal costae. Cells attach with the end of the posterior to the substrate. Common at Cape Tribulation.

Saepicula pulchra Leadbeater, 1980. Cell when dried 3-5 microns long x 2-3 microns wide, the flagellum 3-7_microns long. Lorica 10-13 microns long consisting of two chambers. Transverse costae of posterior chamber numerous, longitudinal costae numerous converging posteriorly to a blunt tip. Anterior chamber containing 10 divergent longitudinal costae each consisting of one costal strip. In most cells one end of a diagonally located strip attached to each longitudinal costal strip mid-way along its length. Anterior tips of longitudinal costae apiculate and attached to the anterior transverse costa at or between junctions of adjacent costal strips.

Saepicula leadbeateri Takahashi, 1981. Lorica bell-shaped, with two slight constrictions, 16.5 microns high, composed of open anterior part consisting of nine to 10 thick and slightly curved costal strips, cell chamber consisting of about 18 slightly oblique costal strips, and about 20 thick transverse costal strips on the anterior part. Longitudinally or obliquely arranged costae consist of three costal strips each, the anterior and second costal strips cut sharply and pointed at anterior end and abruptly cut at other end, strips 5.8-6 microns long. Transverse costal strips botuliform, 2.5 microns long and 0.22 microns thick, loosely deposited.

Saroeca attenuata Thomsen, 1979. Cell solitary, planktonic. Cell 4 x 2 microns (3-5.5 x 2-3 microns), flagellum 10-14 microns long, surrounded by a ring of tentacles. Lorica 25 microns long (20-30 microns), lorica chamber (i.e. lorica exclusive of anterior spines and posterior pedicel) 10 microns long (7.5-13.5 microns), pedicel 5 microns long (3-10 microns). Spines commonly six or seven, rarely eight. Longitudinal costae converging at posterior end of lorica chamber and connected to each other in different ways before transition into pedicel. One transverse costa, 5 microns in diameter (4-6.5 microns), mostly composed of 10 or 11 costal strips, crosses the exceptionally long and slender anterior longitudinal costal strips at the point where these strips are widest. The junctions are mostly "T" -junctions (i.e. the point of attachment is on the middle of the transverse costal strip).

Savillea micropora (Norris, 1965) Leadbeater, 1975. Cells spherical to ovoid, with collar and flagellum. Cells located in base of lorica composed of longitudinal and transverse costae. Base of lorica with numerous closely spaced transverse costae, expanded anterior part of lorica composed of approximately 12 longitudinal costae traversed at regular or irregular intervals by 4-6 transverse costae. Terminal transverse costa forming pore with small diameter (approximately 1 microns diameter). Cell 2.5-3 microns diameter, base of lorica 1.6-3.5 microns long, 3 microns diameter, anterior part of lorica 5-6.3 microns long, 5-6.3 microns diameter.

Savillea parva (Ellis, 1930) Loeblich III, 1967. Cells are 2.5-4 microns (spherical), lorica 10-10.5 microns in length. The cell body is situated at the bottom of the lorica, the pseudopodial collar extends about two-thirds of the way up the lorica, and the flagellum extends to the top of the lorica. Unlike Savillea micropora, a flagellum is always present and active.

Stephanoeca (steff-ann-owe-eek-a) is a collar flagellate in which the body is located within a lorica, which is made up of siliceous spicules. In this case the spicules cannot be seen individually. One cell (to the left) is active and has a flagellum projecting from the anterior of the cell and the base of the flagellum is surrounded by a collar of fine pseudopodia. The cell to the right seems to have encysted. Phase contrast micrograph.

Stephanoeca (steff-ann-o-eek-a) diplocostata Ellis, 1929. Collar flagellate with lorica divided into two chambers by a waist at about two fifths of the distance from the base of lorica. Cells have a lorica with transverse and horizontal costae. The cells have a single apical flagellum. The flagellum is as long as the cell body. The cell body is about 10 microns long and fills the posterior chamber of the lorica. The lorica attaches to the substrate with a stalk or with the posterior end of the lorica. Rarely observed.

Stephanoeca diplocostata Ellis, 1930. The cell, which bears a single anterior flagellum and a collar of 20-25 tentacles, is lodged in the posterior chamber of the lorica. About 15 longitudinal costae run from the base of the posterior chamber to the top of the anterior chamber. Four transverse costae encircle the posterior chamber and about three double costae encircle the anterior chamber. Anteriorly the longitudinal costae curve inwards. Lorica 14.5-15.5 microns long.

Stephanoeca paucicostata Throndsen, 1969. Cells have 12-14 longitudinal costae and 3 transverse costae, one of which is the anterior rim, in its anterior chamber and an irregular arrangement in the posterior chamber. Overall length of the lorica is 16-17 microns The anterior lorica chamber is 10 microns long and 9 microns wide. The length of posterior lorica chamber is 6.5 microns, its width is 6.4 microns

Stephanoeca elegans (Norris, 1965) Throndsen, 1974. Cells spherical to ovoid, with collar and flagellum. Cells located in base of lorica composed primarily of 18 longitudinal costae. Costae converging at base of lorica, forming a narrow basal area that encloses cell. One or two transverse costae encircling lorica at anterior end of cell. Longitudinal costae abruptly diverging in area above transversecostae forming a broad chamber that gradually narrows to the orifice. A single transverse costa encircles the opening. Cell diameter 3-3.5 microns, lorica diameter at base 4-5 microns, length of lorica base 4-6.5 microns, length of anterior lorica chamber 8-11 microns, widest diameter of anterior lorica chamber 8-8.5 microns, orifice diameter 3.5-6.5 microns

Stephanoeca cupula (Leadbeater, 1972) Thomsen, 1988. The ovoid cell bears a single anterior flagellum surrounded by a collar of approximately 25 tentacles. The lorica is about 7.5 microns and cup-shaped and both chambers contain 8-10 longitudinal costae. The lower chamber is girdled by approximately three transverse costae whilst the anterior chamber is encircled by two transverse costae, one costa forming the anterior ring and the other forming a ring mid-way along the length of the chamber. The protoplast is situated within the posterior chamber with the flagellum and collar projecting into the anterior chamber.

Stephanoeca ampulla (Kent, 1880) Ellis, 1930. Cell truncate-ovate, average length 5 microns, width 45 microns, when adult, almost filling lower part of lorica, when immature, and therefore smaller, a short anchoring filipode occ1sionally connects the bases of cell and lorica. Collar and flagellum short, projecting into the upper expanded part of lorica. Movements of flagellum languid, never of such a character as to produce definite food-bringing currents. Shape of lorica resembles that of a crown, hence the generic name, sessile. Average total length of lorica: 15 microns, upper portion 9 microns, of lower 6 microns, greatest width of upper portion: 8.5 microns, of lower 5.5 microns Diameter of mouth of lorica: 4 microns Number of costae: 16 longitudinal, extending from top to bottom of lorica, 8 transverse, on lower part of lorica.

Stephanoeca campanula (Kent, 1880) Boucaud-Camou, 1967. Lorica goblet or bell shaped, scarcely longer than broad, the basal region narrower, conically pointed, the anterior two-thirds expanding abruptly and in a marked manner in comparison with the first-named area, the anterior border widest, but not everted, pedicel equling the length of the lorica, contained protoplast symmetrically ovate, occupying and projecting slightly beyond the conical basal area, the fully expanded collar enclosed entirely within the wider anterior area of the cavity of the lorica, the flagellum extending for about half its length beyond its anterior border, two contractile vacuoles, posteriorly located, nucleus spherical, subcentral. Length of lorica 32 microns

Stephanoeca deminutiva (Norris, 1965) Throndsen, 1974. Cells ovoid, with collar and flagellum. Cells within loricae composed of longitudinal and transverse costae. Lorica with narrow basal part enclosing cell and broader anterior part enclosing collar. Broad part of lorica composed of 7 longitudinal costae, evenly spaced, three or four transverse costae spaced at more or less equal intervals. Base of lorica with 4-6 transverse costae, more or less evenly spaced. Longitudinal costae not observed in basal area. Loricae sessile or on stalks up to 6.5 microns long. Cell 4-5 microns long, 3-3.5 microns wide, base of lorica 3.5-6.5 microns long, 3-5 microns wide, anterior part of lorica 6.5 microns long, 5-8 microns wide, orifice 5-6.5 microns wide.

Stephanoeca complexa (Norris, 1965) Throndsen, 1974. Cells ovoid, with collar and flagellum. Cells located in base of lorica composed of irregularly arranged costae. Lorica with narrow basal part enclosing cell, and expanded anterior section with open end. Basal part of lorica of 4-5 more or less transverse costae and 10-12 more or less longitudinal costae. Some loricae have numerous fine transverse costaeaggregated at the junction of the two parts of lorica. Longitudinal costae in anterior lorica curving at orifice and joining with adjacent costae. Transverse costae. In anterior lorica often in irregular pairs, sometimes present only as short pieces. Loricae sessile or on stalks up to 8 microns long. Cell 5 microns diameter, 6.5 microns long. Lorica diameter at base 5-6.5 microns, length of basal part 6.5-8 microns, length of anterior lorica chamber 9.5-11 microns, diameter of anterior lorica chamber 8-11 microns

Portrait of the marine acanthoecid choanoflagellate, Stephanoeca complexa (Norris, 1965) Throndsen, 1974. DIC.

Portrait of the marine acanthoecid choanoflagellate Collected from tide pools at Alkai Beach,Seattle, Washington 47°35'41.87" N;122° 23'17.57" W.January 2006.DIC.

Detail of longitudinal and transverse costae of the lorica of Stephanoeca complexa. Collected from tide pools at Alkai Beach,Seattle, Washington 47°35'41.87" N;122° 23'17.57" W.January 2006.DIC.