Chrysochromulina lanceolata

Taxonomy:

Catalog entries: Chrysochromulina lanceolata

Original description: Lancet-shaped cells with two slightly asymmetric anterior arms and a posterior tail. Cells 21–38 x 7–12 x 3–7 µm. Two subequal flagella, 30–51 and 29–44 µm long, respectively. Haptonema shorter than the flagella, 23–37 µm long, held straight forward during swimming. A refringent body in the posterior part, just before tail attenuation. Two types of scales. Outer layer with oval scales 1.3–1.6 x 0.9–1.2 µm, carrying a spine approximately equal in length to major scale radius and supported by four struts extended to the rim. Inner layer with elongate plate scales, 1.13–1.47 x 0.8–0.93 µm. Proximal face of both scale types with about 108 radiating ribs, distal face with crossed microfibrils. The cells of C. lanceolata are characterized by their typical lancet shape with pointed ends (Fig. 2, a–f). Cells are easily recognized under living conditions from their angular shape and their way of swimming. They were detected at 40x magnification (objective 4x) under dark-field illumination of the natural sample. They swim gently, mostly in a backward direction, with alternate gyration. The haptonema is extended straight forward, the flagella also directed forward with homodynamic movements (Fig. 2, a–f). Changes from forward to backward direction are frequent, the flagella beating along the cell body (Fig. 2, a–f).

Cells can also make a short stop and attach to a support with their haptonema (Fig. 2c). The two flagella and the haptonema are inserted in a deep depression delimiting two anterior arms, subequal in length, but not exactly symmetrical, the right arm being truncate at its extremity (Fig. 2, a, c, d, and e). Fixation may induce some shrinkage and morphological changes with TEM and SEM procedures. The asymmetry of the arms is more pronounced after fixation (Fig. 3a). Cell length is 21–38 µm with some variation of the tail length. The two flagella, subequal in length, measure 30–51 µm and 29–44 µm. The haptonema is shorter than the flagella (Fig. 2, a–e), measuring 23– 37 µm. Although held straight during swimming, it is able to coil (Fig. 2f). A refringent body is clearly visible in the posterior part of the cell (Fig. 2, a–d). A scaly investment can be observed both in living cells (Fig. 2e) and as an empty cover shed in SEM preparations (Fig. 3b). EM reveals two types of covering scales. The outer layer is made of spiny scales (Fig. 3,a–d) with an oval base measuring 1.3–1.6 x 0.9–1.2 µm. The spine is approximately equal in length to the major scale radius, measuring 0.67–0.87 µm. It is supported by four struts attenuated before reaching the rim. The inner layer is made of elongate plate scales, measuring 1.13–1.47 x 0.8–0.93 µm. Their proximal face shows about 108 radiating ribs, their distal face exhibit a pattern of crossed microfibrils difficult to discern (Fig. 3, c–e). The scales are tightly assembled on the cells and a slight shrinkage is visible on SEM preparations (Fig. 3, a and b).

Geological Range:
Last occurrence (top): Extant. Data source:
First occurrence (base): within No known fossil record modern (0-0Ma, base in "Holocene" stage). Data source:

Chrysochromulina lanceolata compiled by Jeremy R. Young viewed: 8-12-2023 Taxon Search: Advanced Search Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=20096 Go to Archive.is to create a permanent copy of this page - citation notes

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