Bursellopsis Corliss, 1960 (ref. ID; 2013)
Class Kinetofragminophora: Subclass Gymnostomata: Order Prostomatida: Suborder Prorodontina: Family Prorodontidae (ref. ID; 2013)
Order Prostomatida: Family Prorodontidae (ref. ID; 4701)

Synonym Bursella Schmidt, 1920 (ref. ID; 4613) or 1921 (ref. ID; 2013)

[ref. ID; 2013]
Body shape either ovoid or irregularly pyriform with truncated anterior region. The large oval or circular apical oral aperture is situated at the base of a wide shallow depression. Body covered with many longitudinal kineties of cilia which curve over the apical region into the apical depression. Cytopharynx supported by basket of trichites. There are 3 rows of double kinetosomes of which either straddle or run towards the oral depression forming a dorsal 'brush'. Macronucleus rounded, contractile vacuole posterior. Planktonic, feeds upon flagellates and rotifers.
Quote; Colin R. Curds "British and other freshwater ciliated protozoa Part I Ciliophora: Kinetofragminophora" Cambridge University Press, 1982 (ref. ID; 2013)


Bursellopsis nigricans (Lauterborn, 1894) (ref. ID; 4613 redescribed paper)
Syn; Holophrya gargamellae Faure-Fremiet, 1924 (ref. ID; 4613); Holophrya nigricans Lauterborn, 1894 (ref. ID; 4613)
Improved diagnosis; Size in vivo 80-200 x 65-180 um; broadly ovoidal to bursiform. 1-2 micronuclei. Extrusomes fusiform. 85-140 ciliary rows and 46-98 circumoral dikinetids. (ref. ID; 4613)
Comments; Synonymy of Holophrya nigricans Lauterborn and H. gargamellae Faure-Fremiet is indicated by many morphological and ecological features, for example, size, large oral apparatus, conspicuous fringe of extrusomes, pelagic habitat, and preferred occurrence in winter. Lauterborn (1894, 1908) studied the cortex in detail and found that each meridional alveoli rows is ciliated. Conversely, the type species of Holophrya, H. ovum Ehrenberg, has a row of alveoli without cilia between each two ciliary rows (Foissner et al., 1994). Thus, we transfer H. nigricans to Bursellopsis, which has each row of cortical alveoli ciliated. We split this species into two subspecies differing mainly in body shape and morphometric features. The improved diagnosis is based on the original description, the redescriptions by Dragesco et al. (1974) and Wilbert (1986), and our data from B. nigricans mobilis, Bursellopsis nigricans nigricans lacks caudal cilia, according to the original description and the redescriptions by Dragesco et al. (1974) and Wilbert (1986). However, we consider the occurrence of caudal cilia as a genus character, and thus suggest that they have been overlooked by the authors mentioned above; possibly, they are less conspicuous than in Bursellopsis nigricans mobilis, B. truncata, and B. pelagica. (ref. ID; 4613)
Bursellopsis nigricans mobilis (Wang & Nie, 1933) (ref. ID; 4613 redescribed paper)
Syn; Holophrya mobilis Wang & Nie, 1933 (ref. ID; 4613)
Improved diagnosis; Size in vivo about 100-200 x 90-180 um (mean about 140 x 110 um); broadly bursiform to ellipsoidal. Two micronuclei. Extrusomes 5-7 um long, 95-140 (mean 116) ciliary rows, about 50 caudal cilia, and 60-98 (mean 75) circumoral dikinetids. (ref. ID; 4613)
Comments; Bursellopsis nigricans mobilis differs from B. nigricans nigricans by the body shape (bursiform to ellipsoidal vs. obovoidal), the number of micronuclei (2 vs. 1), the number of ciliary rows (116 vs. 90), the number of circumoral dikinetids (75 vs. 46-60) and, possibly, by the more distinct caudal cilia. The in vivo appearance and the ciliary pattern of B. nigricans mobilis are very similar to those of B. pelagica. In vivo, B. nigricans mobilis can be distinguished from B. pelagica by the fusiform extrusomes (trod-shaped in B. pelagica). In the scanning electron microscope, B. nigricans mobilis differs from B. pelagica by the long (about 4 um in the scanning electron microscope) cilia of brosse row 1, which has a conspicuous, serrated appearance. (ref. ID; 4613)
Neotype slides; Two neotype slides with protargol-impregnated specimens have been deposited in the Oberoserreichische Landesmuseum in Linz (LI), Austria. (ref. ID; 4613)
Bursellopsis nigricans nigricans (Lauterborn, 1894) (ref. ID; 4613 redescribed paper)
Improved diagnosis; Size in vivo about 80-180 x 65-150 um; broadly obovoidal. 1 micronucleus. Extrusomes about 3-4 um long. 85-104 (mean 90) ciliary rows and 46-60 circumoral dikinetids. (ref. ID; 4613)
Description; 1) Size in vivo about 80-180 x 65-150 um, usually about 90-140 um long. 2) Body obovoidal with distinctly depressed oral area, circular in transverse view; specimens thus look like rotating globules at low magnification. Shape very fragile, soon becoming irregular during microscopic observation. 3) Macronucleus globular to ellipsoidal, near mid-body. Usually 1 micronucleus. 4) Contractile vacuole in posterior pole area, eccentric, with single excretory pore. 5) Extrusomes fusiform, 3-4 um long, numerous and thus forming distinct peripheral fringe. Cytoplasm with many vacuoles. No symbiotic green algae. Cortex hexagonally patterned. 6) 85-104 (mean 90) meridional ciliary rows, which commence at circumoral ciliary row (undulating membrane) and extend to posterior end. Inconspicuous caudal cilia very likely present. 6-10 ciliary rows abut at acute angles to adoral organelles. 2-3 condensed somatic ciliary rows right of posterior end of adoral organelles. 7) Oral opening occupies about 1/3 of anterior body end, circular, and fragile; appears +/- distinctly depressed in undisturbed specimens. Oral basket inconspicuous in vivo. Undulating membrane (circumoral ciliary row) circular, composed of about 46-60 dikinetids each associated with a long rod to form the oral basket. Brosse (adoral organelles) enklitoloph-dexiotrop, composed of 3 rows extending 1/4 to 1/3 of body length; each row consists of oblique dikinetids with, possibly, a short cilium associated with the anterior basal body only. 8) Movement not known, likely inconspicuous as in congeners (Bursellopsis pelagica). (ref. ID; 4613)
Comments; Bursellopsis nigricans nigricans differs from B. nigricans mobilis by the body shape (obovoidal vs. bursiform to ellipsoidal), the number of micronuclei (1 vs. 2), the number of ciliary rows (90 vs. 116), the number of circumoral dikinetids (40-60 vs. 75) and possibly, by the more indistinct caudal cilia. Bursellopsis truncata is slightly smaller (50-110 um), bursiform, and has fewer ciliary rows (52-69). Bursellopsis pelagica is larger (130-250 um) and thus has many more ciliary rows (130-198; mean 159). Bursellopsis spumosa is about 500 um long and has symbiotic green algae Pelagothrix species are smaller (40-60 um) and have zoochlorelae. (ref. ID; 4613)
Bursellopsis pelagica (ref. ID; 4613 original paper)
Diagnosis; Size in vivo about 180 x 160 um; broadly bursiform. Very likely amicronucleate. Extrusomes rod-shaped, about 5 um long. 159 ciliary rows, 80 caudal cilia, and 121 circumoral dikinetids on average. (ref. ID; 4613)
Description; 1) Size in vivo 130-250 x 130-230 um, usually about 180 x 160 um. 2) Body bursiform with +/- distinctly depressed oral area, circular in transverse view; specimens thus look like rotating globules in the dissecting microscope. Shape very fragile, soon becoming irregular during microscopic observation. 3) Macronucleus near mid-body, but slightly eccentric, that is, usually underneath brosse; globular to slightly ellipsoidal, about 50 x 40 um in protargol-impregnated specimens. Micronucleus very likely lacking because not found in properly orientated and impregnated specimens. 4) Contractile vacuole in posterior pole area, with single, large excretory pore at border of somatic ciliature and caudal cilia area. 5) Extrusomes rod-shaped with narrowed ends, in vivo about 5 x 0.5 um, very numerous and thus forming distinct peripheral fringe providing cells with a greyish colour at low magnification (< / - 100 x); found in rows right of somatic ciliary rows, in caudal cilia area, and within oral basket, where they produce a compact, bright zone, leaving blank only the central area. Cytoplasm with rather many bright vacuoles. No symbiotic green algae. Cortex hexagonally patterned. 6) 130-198 (mean 159) meridional ciliary rows, which commence at oral opening and extend to posterior end, leaving blank a small area occupied by 60-100 loosely spaced, about 20 um long caudal cilia, which are difficult to recognize in living cells; about 15 ciliary rows abut at acute angles to the adoral organelles. At posterior end of adoral organelles some specialized ciliary rows, as described by Hiller (1991) in Bursellopsis truncata, which, however, are recognizable only in silver nitrate-impregnated specimens. 7) Oral opening occupies about 1/3 of anterior body end, circular fragile, that is, soon because slit-like and undulating in distorted specimens; appears +/- distinctly depressed in undisturbed specimens, whose pharyngeal plasm is frequently excavated bowl-like, but becomes flat or convex in prepared specimens. Oral basket inconspicuous in vivo, filled with cytoplasm and extrusomes, consists of rather thick rods converging to body centre. Undulating membrane (circumoral ciliary row) circular, composed of 97-160 (mean 121) dikinetids each associated with a very short ciliary stump and a long oral basket rod. Brosse (= adoral organelles) distinctly enklitoloph-dexiotrop, composed of 3 rows extending about 25% of body length; each row consists of oblique dikinetids having a short cilium associated with the anterior basal body only. 8) Movement inconspicuous, swims slowly by counter-clockwise (seen from posterior towards anterior cell pole) rotation about main body axis. (ref. ID; 4613)
Comments; Easily confused with Bursellopsis nigricans mobilis (extrusomes rod-shaped vs. fusiform, 130-198 vs. 95-140 ciliary rows, 97-160 vs. 60-98 oral dikinetids, amicronuleate (?) vs. 2 micronuclei). Bursellopsis spumosa has symbiotic green algae and is 2-4 times larger than B. pelagica. Bursellopsis truncata and B. nigricans nigricans are smaller (< / - 140 um) and thus have much fewer ciliary rows and oral dikinetids. (ref. ID; 4613)
Etymology; pelagicus (lat.), living in the sea. (ref. ID; 4613)
Type location; Hoglworther See, a small lake in southern Bavaria, Germany (47 degrees 49'N, 12 degrees 50'E (ref. ID; 4613)
Type slides; Four slides (1 holotype, 3 paratypes) with protargol-impregnated specimens have been deposited in the Oberosterreichische Landesmuseum in Linz (LI), Austria. (ref. ID; 4613)