Xystonellopsis
Xystonellopsis Jorgensen, 1924 (ref. ID; 3597) = Xystonelopsis (ref. ID; 3319)
[ref. ID; 3597]
Lorica usually elongate, consisting of a cylindrical or subcylindrical bowl, a short or long pedicel with or without a knob and a skirt, and an apical lance; cavity generally stretching to a distal end of the lance; oral margin usually entire, thick-walled; longitudinal or spiral striae, ridges, or fins sometimes present on the pedicel; wall trilamellate, middle layer composed of a distinct or fine prismatic structure. (ref. ID; 3597)
Type species; Xystonellopsis paradoxa (Cleve) Jorgensen (ref. ID; 3597)
- Xystonellopsis brandti (Laackmann) Jorgensen (ref. ID; 3597)
- Xystonellopsis cymatica (Brandt) Jorgensen (ref. ID; 3597)
- Xystonellopsis dahli (Brandt) (ref. ID; 3597)
- Xystonellopsis dicymatica (Brandt) Kofoid & Campbell (ref. ID; 3597)
- Xystonellopsis heroica Kofoid & Campbell (ref. ID; 3597)
- Xystonellopsis heros (Cleve) Kofoid & Campbell (ref. ID; 3597)
- Xystonellopsis inaequalis Kofoid & Campbell (ref. ID; 3597)
- Xystonellopsis mascarensis Kofoid & Campbell (ref. ID; 3597)
- Xystonellopsis paradoxa (Cleve) Jorgensen (ref. ID; 3597)
- Xystonelopsis constricta (ref. ID; 3319)
- Xystonelopsis cymatica (ref. ID; 3319)
- Xystonelopsis brandti (ref. ID; 3319)
- Xystonelopsis paradoxi (ref. ID; 3319)
- Xystonelopsis pinnata (ref. ID; 3319)
Descriptions
Lorica elongate, 6.7 oral diameters in length; oral rim entire; bowl dilated by thickening of the wall in the suboral region, gradually tapering very slightly (5 degrees) below the suboral expansion, more abruptly (20 degrees) in the suboral region, again slightly (8 degrees) in the part regarded as a pedicel; lance 0.17 of the total length, conical (10 degrees) with an acute tip; wall almost translucent, with a very fine prismatic structure; vertical short fins present on the conjunction of the pedicel and the lance. (ref. ID; 3597)
Comments
The species differs from X. heros (Cleve) in smaller size and having a pedicel-like aboral part and from X. heroica Kofoid & Campbell in the constriction of the aboral region including a lance. (ref. ID; 3597)
Measurements
Length 195; oral diameter 29 um. (ref. ID; 3597)
Descriptions
Lorica comparatively stout, chalice-shaped, 4.6 oral diameters in length; oral rim smooth; bowl with a single elevated suboral band, gradually tapering (8 degrees) in its subcylindrical middle part, then abruptly narrowing (33 degrees) in the aboral region; pedicel rather stout, 0.25 of the total length without a lance; knob small, with a slightly widened angular margin, its width 0.24 oral diameter; apical lance slender, tapering (4 degrees) to a pointed terminal; wall thickest in the suboral band, rapidly thinning to the oral margin and gradually to the aboral end, reticulated with minute hexagons being larger below the suboral dilated band. (ref. ID; 3597)
Comments
The species differs from X. mascarensis Kofoid & Campbell in having a stout pedicel. Kofoid & Campbell's allied species, X. cyclas Kofoid & Campbell, X. spicata (Brandt), and X. crassispinosa Kofoid & Campbell, are probably varieties of this species. The first is a variety having striae on the caudal knob, the next is one with a wide elevated aboral band, and the last is a form provided with a stout apical lance which is slender in the typical form. Brandt's variety is constricted below the suboral expansion; this specimen was probably artifically deformed by constriction caused by the fixer of the plankton as shown by Jorgensen (1924) in fig. 57b. (ref. ID; 3597)
Measurements
Length 233; oral diameter 50 um. (ref. ID; 3597)
Descriptions
Lorica chalice-shaped, 6.7 oral diameters in length; oral margin smooth; bowl cylindrical in the anterior half of the lorica, aborally narrowing (25 degrees); pedicel and a lance not differentiated, having about six aboral ridges extending up to the posterior part of the aboral region; wall almost translucent because of a very fine prismatic structure. (ref. ID; 3597)
Measurements
Length 388; oral diameter 58 um. (ref. ID; 3597)
Descriptions
Lorica elongated goblet-shaped, 5.4 oral diameters in length; oral margin entire; suboral region forming an elevated band with two angular rings, the lower a little larger than the upper, respectively 1.4 and 1.3 oral diameters in diameter, distance between them 1.5 of the total length; bowl slightly narrowing (15 degrees) below the suboral band, more abruptly (38 degrees) in the aboral region; pedicel slender with a knob and an apical lance, 0.45 of the total length including a lance, posteriorly tapering (9 degrees); knob an erect cone of 50 degrees with a sharply edged skirt, its basal diameter 0.22 oral diameter; lance conical (8 degrees) to a pointed terminal, 0.1 of the total length; wall thickened in the suboral band. (ref. ID; 3597)
Comments
The species differs from X. inaequalis Kofoid & Campbell in the shape of the lower suboral ring which is not expanded so widely in this species as in X. inaequalis and from X. mascarensis Kofoid & Campbell in having two suboral rings. (ref. ID; 3597)
Measurements
Length 242; oral diameter 45 um. (ref. ID; 3597)
Xystonellopsis heros (Cleve) Kofoid & Campbell (ref. ID; 3597)
Descriptions
Lorica slender, 7.1-7.7 oral diameters in length; bowl cylindrical in the anterior 0.45-0.55 of the lorica, tapering aborally (17-20 degrees) into an indefinite pedicel with a slight knob having a somewhat serrated skirt; knob 0.31-0.35 oral diameter in transdiameter; lance conical (13-15 degrees), 0.095 of the total length, its tip sharply pointed; wall almost translucent due to very minutely prismatic structure, subuniform in thickness in the bowl, with about eight ridges occupying 0.2 of the total length from the skirt. (ref. ID; 3597)
Comments
The species differs from X. dahli (Brandt) in the stout pedicel and the fully developed skirt of the knob. Laackmann's X. heros var. gaussi (1909) and Kofoid & Campbell's X. acuminata (1929) seem to be stout forms of this species. (ref. ID; 3597)
Measurements
Length 516-555; oral diameter 67-72 um. (ref. ID; 3597)
Descriptions
Lorica stout, consisting of a subcylindrical bowl and a duplicate knob with a marked lance, 4.85-5.00 oral diameters in length; oral margin entire; bowl with a wide raised suboral band, somewhat conical (3-8 degrees) in its middle; aboral region convex conical to an aboral constriction, provided with several more or less spiral plate-like ridges which are usually stretched out to an upper ring of the knob and 0.17 of the total length in length; knob great, with double edges rings, distance between them 0.06-0.08 of the total length, upper ring 0.67 and the lower 0.57 of an oral diameter; lance stout, 0.13-0.15 of the total length, conical (25-30 degrees) with a pointed tip; wall thickened in the suboral band and the knob. (ref. ID; 3597)
Comments
The species differs from the other species of Xystonellopsis in possessing a duplicate knob. (ref. ID; 3597)
Measurements
Length 197-200; oral diameter 40 um. (ref. ID; 3597)