Pleurotrocha fontanetoi, 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 : 173-176

Pleurotrocha fontanetoi sp. nov.

( Figs 18 , 19 )

Diagnosis. Head short, narrower than trunk; foot long, 2−3 pseudosegments; toes conical, with offset distal half; corona slightly oblique; rami with long obtuse alulae; fulcrum with large basal plate; manubria with large head and incurved cauda; a ribbon composed of two bands of short and long sclerite bodies laterally from dorsally recurved part of rami.

Type locality. Punta della Madonna di Ponente, Elba Island, Tyrrhenian Sea, Italy. In psammon collected on 28.09.2006, 50 m from shoreline and depth of 40 m; water temperature 22 °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 33099, RIR 255.

Paratypes. One female from type locality in RBINS, No. IG 33099, RIR 256; 5 mounted paratypes and 6 SEM trophi preparations in Department of Biology, University of Antwerp.

Additional material. Several specimens from other sampling stations at Elba Island, and Cap Bénat, Côte d’Azur (see Tab. 2 species list).

Etymology. The species is dedicated to dr. Diego Fontaneto in recognition of his important contributions to our knowledge of the Rotifera.

Description of female. Body ( Fig. 18 A) stout fusiform, somewhat gibbous. Head and foot offset by transversal fold. Head short, narrower than trunk, with transversal fold. Corona slightly oblique, with small lateral tufts of cilia. Dorsal antenna near posterior 1/3 of head. Eyespot on brain, a colourless globule with two minute redpigmented granules ( Fig. 18 B). Trunk elongate-ovate with transversal fold in posterior 1/3. Tail large, rounded. Foot long, cylindrical, 2‒3 pseudosegments, occasionally appearing wrinkled proximally. Toes ( Figs 18 D, E) short, stout conical, tapering to tubular tips, with more or less distinctly offset distal half. Pedal glands club-shaped with reservoirs at base of toes. Stomach separated from intestine by weak constriction. Gastric glands large, rounded.

Trophi ( Figs 18 F −I, 19) asymmetrical, left more strongly developed than right. Rami with large, elongate blunt alulae pointing latero-caudally, and large dorsally recurved apical branch bearing comb of tiny toothlets at inner margin; basal rami part with irregular knob-shaped teeth on inner margins, and strong, left basal apophysis; basal chambers fairly small, left one with large opening. Fulcrum robust, long, plank-shaped and fairly high, ventral margin reinforced, distal end broadly expanded into oblique oval plate. Unci five incompletely connected teeth of decreasing length, first two teeth with head, the others linear; left uncus more strongly developed, its first tooth with distinct head and prominent medial projection at ventral margin; right uncus more slender, head of teeth weak, projection at ventral margin weak; subuncus composed of few irregular knob-like prominences. Manubria with relatively large elongate head and dorsally recurved cauda, left manubrium largest; openings of ventral and medial chamber narrow, elongate, opening of dorsal chamber broad. A broad ribbon ( Figs 19 E, I, J: r) composed of two bands of long (frontal) and short (caudal) sclerite bodies inserted laterally from recurved distal part of rami, and partly covered by malleus.

Description of male. Male more or less similar in habitus to female, with small head, oval trunk, and long foot composed of c. 5 pseudosegments; toes conical with more or less distinctly offset distal part.

Measurements. Female, body (N=5): total length 150‒180 µm, toe 17‒28 µm; trophi (N=5): length 21.8−23.3 µm, ramus with alulae ~13 µm, fulcrum 9.9‒13.3 µm, left uncus 9.1‒12.8 µm, right uncus 8.1‒9.0 µm, left manubrium 18.7‒20.9 µm, right uncus 11.1‒15.6 µm, ribbon of sclerite bodies (length × height) ~10 × 4.8 µm. Male (N=4): total length ~120 µm, toe 18−20 µm.

Comments. The species is allocated to the genus Pleurotrocha Ehrenberg, 1830 on basis of the stout body with well-separated head and trunk, the long cylindrical foot with two short toes, the sligthtly oblique corona with lateral tufts of cilia, auricles absent, a single cerebral eyespot, and fairly large pedal glands with reservoir; the trophi are virgate, with long fulcrum and dorsally recurved rami ( Koste 1978; Nogrady et al. 1995). In fixed material, P. fontanetoi sp. nov. can be mistaken for Proales similis Beauchamp, 1907 but is unambiguously differentiated from the latter and all other Notommatidae by its characteristic trophi.

Distribution and ecology. The species was found in psammon from the Côte d’Azur and Elba Island, Tyrrhenian Sea, 50 m and 1 km off shore, depth 20−40 m, June, September, water temperature 17−23 °C.

Figures

FIGURE 18. Pleurotrocha fontanetoi sp. nov. A. Female, dorsal; B. eye, female; C. male, dorsal; D. toe, female, lateral; E. toes, female, dorsal; F. trophi, complete set, ventral; G. incus, lateral; H. left malleus, outer view; I. right malleus, outer view. Scale bars: A, C: 50 µm; D − I: 10 µm.

FIGURE 19. Pleurotrocha fontanetoi sp. nov., SEM photographs of trophi. A. Complete set, ventral; B. incus, ventral; C. incus, lateral right; D. right uncus, inner view; E. distal part of ribbon of short and long sclerite bodies; F. left manubrium, outer view; G. right manubrium, outer view; H. incus, oblique ventro-caudal; I, J. complete set, oblique ventro-frontal. R: ribbon of sclerite bodies. Scale bars: A − D, F − J: 10 µm; E: 1 µm.