Encentrum loefgreni, De Smet, Willem H., 2015

De Smet, Willem H., 2015, Rotifera from the Mediterranean Sea, with description of ten new species, Zootaxa 4028 (2), pp. 151-196 : 164-165

Encentrum loefgreni sp. nov.

( Figs 8 , 9 )

Diagnosis. Large-sized Encentrum about 200 µm long (slightly contracted). Trophi subgenus Encentrum type; rami smoothly curved; rami outline oboval; median rami opening lenticular; basal rami chambers with distinct triangular alula; apical ramus tooth indistinctly offset; preuncinal teeth in line with apical rami teeth; fulcrum broad basally, tapering to blunt end.

Type locality. Îlot de la Fourmigue, Baie du Lavandou, Côte d’Azur, France. In psammon collected on 0 2.06.2010, 3.5 km from the shoreline and depth of 15 m; water temperature 16 °C.

Holotype. A female in a permanent, glycerine glass slide mount deposited in the Royal Belgian Institute of Natural Sciences ( RBINS), Brussels, Belgium, No. IG 33082, RIR 219.

Paratypes. One female from type locality in RBINS, No. IG 33082, RIR 249; 3 mounted paratypes and 3 SEM trophi preparations in Department of Biology, University of Antwerp.

Additional material. A single specimen from sublittoral of Cap Bénat, Baie du Lavandou, Côte d’Azur, and 2 from La Formiche di Ponente, Elba Island, Tyrrhenian Sea.

Etymology. The species is named for Mr. Bart Löfgren, in recognition of his much appreciated sampling effort during scuba diving.

Description of female. Body plump fusiform ( Fig. 8 ). Head offset by distinct neckfold, c. 1/4−1/3 total length. Rostrum indistinct, almost straight to broadly rounded. Corona strongly oblique to ventral. Dorsal antenna near neckfold. Trunk with two pseudosegments, widest near mid-length. Tail short, broadly rounded. Foot broad, a single pseudosegment. Toes ( Fig. 8 B) c. 1/7 total length, divergent, base narrower, dorsal margin slightly curved, ventral margin weakly undulate, indented near mid-length, near tip converging to more or less tubular point; a very weak transversal fold at about 1/3 from tip; a small rounded reservoir somewhat above mid-length. Small caudal antenna between bases of toes. Eyes not observed, possibly absent. Brain saccate; retrocerebral sac present. Proventriculus large, spherical, distinctly offset from stomach. Gastric glands ovate, without? stalks. Pedal glands small, clubbed. Vitellarium with 8 nuclei.

Trophi ( Figs 8 C, 9) subgenus Encentrum - type ( De Smet 1997). Rami outline oboval with triangular posterolateral alulae on basal chambers; median rami opening lenticular; basifenestrae and subbasifenestrae small, rounded. Rami curved, broad at base, tapering to indistinctly offset short apical tooth. Preuncinal teeth small, with short shaft and head, in line with apical rami teeth; apical rami teeth and preuncinal teeth without cardal apophysis. Fulcrum short, c. 2/3 ramus length, narrow and parallel-sided in dorsal/ventral view; in lateral view broad basally, gradually tapering to narrow blunt tip. Unci long, c. 1/2 ramus length, slender; shaft very long, head very short c. 1/ 4 uncus length, very weakly offset from shaft. Intramallei long, slightly longer than uncus, more or less sockshaped, base broad with short, rounded medio-lateral basal expansion ventrally; distal half narrow. Supramanubria absent. Manubria c. 3/4 incus length, rod-shaped, more or less evenly curved with crutched cauda; head with small dorsal and ventral expansion with small caudal opening.

Measurements. Body (N=3): total length (slightly contracted) up to 255 µm, toe 34‒35 µm; trophi (N=3): length 41‒44 µm, ramus 18.8 µm, fulcrum 11.2‒12.6 µm, uncus 8.6‒9.4 µm, preuncinal tooth 3.0‒3.5 µm, intramalleus 9.8‒10.8 µm, manubrium 24.6‒26.8 µm.

Comments. Encentrum loefgreni sp. nov. is univocally distinguished from its known congeners by the characteristic shape of the trophi.

Distribution and ecology. The species was found in low numbers in the sublittoral psammon samples from the Côte d’Azur and Tyrrhenian Sea, at distances of 50 m to 3.5 km from the low tide mark and depths between 17 and 40 m. It was present in samples of June and September, at water temperatures of 17−21 °C.

Figures

FIGURE 8. Encentrum loefgreni sp. nov. A. Female, ventral; B. toe, lateral; C. trophi, ventral. Scale bars: A: 50 µm; B, C: 10 µm.

FIGURE 9. Encentrum loefgreni sp. nov., SEM photographs of trophi. A. Complete set, ventral; B. detail, dorsal; C. detail, ventral; D. complete set, ventro-lateral; E. detail, ventro-frontal. Scale bars: 10 µm.