Encentrum longirostrum Tzschaschel, 1978

De Smet, Willem H., 2015, Rotifera from the Mediterranean Sea, with description of ten new species, Zootaxa 4028 (2), pp. 151-196 : 186-187

Encentrum longirostrum Tzschaschel, 1978

The general morphology of the Mediterranean specimens conforms to the description of E. longirostrum . A minor difference concerns the toes which show a minute terminal acute point distally from the ventral opening of the pedal glands, not mentioned by Tzschaschel (1979).

The species was found in sublittoral psammon from the Côte d’Azur and Elba island, from 50 m to 3.5 km off shore and 15 to 20 m deep; June, September; water temperature 16−23 °C. Encentrum longirostrum was to date only known from its type locality, a semilotic sandy beach of Uthörn Island, North Sea, Germany ( Tzschaschel 1979, 1980, 1983).

Redescription of trophi by SEM. ( Fig. 28 ) Rami outline oboval with blunt postero-lateral corners; median rami opening lenticular. Rami curved, broad at base, tapering to offset short oblique acute apical tooth (left) or simple tip (right); right ramus ventrally with small blunt toothlet at outer margin c. 1/4 from tip pointing to anterior ( Fig. 28 C: t), and short, blunt outcurved posterior projection near junction with left ramus ( Fig. 28 C, D: pp). Preuncinal teeth in line with curved rami, slender, with short shaft and acute head. Fulcrum long, c. 2/3 ramus length, narrow and parallel-sided in dorsal/ventral view; in lateral view broad at base, gradually tapering to narrow tip. Unci long, c. 2/3 ramus length, slender; shaft very long, head short c. 1/5 uncus length, very weakly offset from shaft; the left head grasps with a dorsal apophysis behind the offset left apical ramus tooth, the right head rests with its shallow apophysis on the blunt tip of the ramus ( Fig. 28 B). Intramallei blunt conical with latero-ventral opening. Supramanubria triangular with drawn-out extension pointing towards trophi axis. Manubria c. 3/5 incus length, rod-shaped, evenly curved with acute cauda in dorsal/ventral view, in lateral view curved with broad triangular head and slightly dorsally recurved end.

Measurements. Body (N=8): total length 170‒210 µm, toe 9‒16 µm; trophi (N=4): length 25‒27 µm, ramus 12.0‒13.3 µm, fulcrum 7.8‒9.0 µm, uncus 8.6‒9.3 µm, preuncinal tooth 3.1‒3.3 µm, intramalleus 3.4‒4.1 µm, supramanubrium 3.7 µm, manubrium 16.2‒18.1 µm.

Comment. The species can not be attributed with certainity to the recognized subgenera.

Figures

FIGURE 28. Encentrum longirostrum Tzschaschel, SEM photographs of trophi. A. Complete set, dorsal; B. detail tips of rami and unci, dorsal; C. complete set, ventral; D. same as B, lateral. pp: posteriorly pointing projection on right ramus; t: toothlet. Scale bar: 10 µm.