Hemiasterella elongata Topsent 1928
Hemiasterella elongata Topsent, 1928 (Figs. 3B, 5; Table 2) Material examined. Four specimens collected: MNCN-Sp66-BV21 from Stn. 21; MNCN-Sp04-DR29 from Stn. 29 m; and MNCN-Sp20-BV33A & B from Stn. 33 (Table 1, Fig. 1). Macroscopic description. Specimens with columnar shape, measuring 5–15 x 4–...
| Main Authors: | , |
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| Format: | Other/Unknown Material |
| Language: | unknown |
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2014
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| Subjects: | |
| Online Access: | https://zenodo.org/record/4908957 https://doi.org/10.5281/zenodo.4908957 |
| Summary: | Hemiasterella elongata Topsent, 1928 (Figs. 3B, 5; Table 2) Material examined. Four specimens collected: MNCN-Sp66-BV21 from Stn. 21; MNCN-Sp04-DR29 from Stn. 29 m; and MNCN-Sp20-BV33A & B from Stn. 33 (Table 1, Fig. 1). Macroscopic description. Specimens with columnar shape, measuring 5–15 x 4–7 mm (Fig. 3B). The individuals are settled on rock pieces, over which slightly expand their base. The surface shows irregularly shallow folds and grooves, mostly running parallel to the longest body axis. The ectoderm is membrane-like and bears a sparse and uneven hispidation. Pore-like aquiferous openings are visible, especially in the lower half of the body. Color is bright to creamy white both in life and after preservation in ethanol. Skeleton. Megascleres are styles, measuring 1316– 2250 x 10–30 µm. They are straight, markedly curved, or just with a slight asymmetrical curvature (Fig. 5A–B). The round end of the styles may also be in a stronglyoxea fashion; the pointing end is regularly acerate or, less frequently, stepped, not very sharp (Fig. 5A–C). Styles with both ends modified into oxea are very rare (e.g., one of 1825 x 10 µm per slide) or absent, depending on the individuals. Microscleres are abundant spherostrongylasters, with only a moderately developed centrum and 10–15 strongylote, slightly conical, spiny actines (Fig. 5A, C–E). Spines are more dense toward the end of the actines. Spherostrongylasters range from 14 to 23 µm in total diameter. The skeletal arrangement shows no axial condensation. Ascending plumose pauci- or multispiculate tracts of styles ramify below the ectosome and may end in plumose tufts that make an hispid surface. There is scarce spongin connecting and packing the spicules in the tracts. Spherostrongylasters are very abundant overall the skeleton, but especially at the periphery, where they make a layer reinforcing the ectosome. Distribution and ecology notes. Rare species, previously known only from its holotype collected at Cape Verde Islands, eastern North Atlantic (Topsent ... |
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