Proales francescae, 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 : 177-179

Proales francescae sp. nov.

( Figs 20 , 21 )

Diagnosis. Female 125−135 µm long; outline trunk broad-oval in dorsal view, with prominent tail overlying basal foot pseudosegment, and small indentations near base of tail; head narrower than trunk, with transversal fold near mid-length; foot with 4 pseudosegments, usually a narrow joint between distal and penultimate pseudosegmenttoes with long drawn out points; rami with 2 alulae each; cauda of manubria incurved at right angle, and slightly enlarged at angle.

Type locality. Cap Bénat, Baie du Lavandou, Côte d’Azur, France. In psammon collected on 0 1.06.2010, 50 m from shoreline and depth of 20 m; water temperature 17 °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 224.

Paratypes. One female from type locality in RBINS, No. IG 33082, RIR 254; 5 mounted paratypes and 7 SEM trophi preparations in Department of Biology, University of Antwerp.

Additional material. Several specimens from most of the study area (see Tab. 2 species list).

Etymology. The species is named for dr. Francesca Leasi, in recognition of her interesting contributions to our knowledge of the Rotifera.

Description of female. Semi-loricate. Trunk ( Fig. 20 ) broad ovate in dorsal view, with prominent small lateral indentations prior to tail; tail ( Fig. 20 B) distinctly offset from trunk, covering basal foot pseudosegment, distal margin straight-cut, mostly with broad, very shallow indentation; ventral to the tail a similar, rounded lobe. Head offset by neckfold, quadratic, dorsally with delicate transverse folds medially and at anterior 1/4, laterally slightly bulging near transversal folds. Corona almost frontal, lateral ciliary tufts absent. Foot ( Fig. 20 B) long, c. 1/3 total length; four pseudosegments, distal longest, penultimate shortest, usually with distinct narrow joint between. Toes long, slender, inner margins straight, outer margins weakly curved, tapering to long drawn-out and slightly offset points. Brain large, saccate; Y-shaped retrocerebral duct. Dorsal antenna near midlength of head; lateral antennae at lateral indentations. Eyespots absent. Proventriculus present. A shallow constriction between stomach and intestine. Gastric glands spherical, stalked. Pedal glands clubbed, extending into trunk, ducts very long.

Trophi ( Figs 20 C, D, 21) malleo-virgate. Rami asymmetrical, each with triangular basal part, and anterior dorsally recurved part narrowing into broad tip with about three shallow knobs; alulae acute, right an additional projection between fulcrum and alula at caudal ramus margin, left near base of fulcrum an additional caudal projection inserted dorsally; right subbasal chamber and subbasifenestra large, ventral, left subbasal chamber and subbasifenestra dorsal; basifenestrae large, dorsal; each ramus ventrally with two broad crenate crests at inner margin, more or less transverse to the trophi axis and pointing antero-ventral; left: a huge basal crest composed of at least 5 fused sclerite elements, and a smaller distal one composed of at least 4 fused sclerite elements; right: a smaller basal and a large distal crest composed of at least 4 fused sclerites; right near base of fulcrum an additional blunt prominence pointing caudally. Fulcrum rod-shaped in ventral view; in lateral view less high, more or less tapering to oblique end. Uncus with 4(5) clubbed teeth, gradually decreasing in size, and 1−2 small, less differentiated minor teeth; teeth connected by membrane; principal teeth with prominence on free margin and distinct preuncinal tooth; subuncus a bundle of fusiform sclerite bodies; the second rami crests fit in the space between the head of the first two uncinal teeth. Manubria long, left somewhat longer, posterior end fairly abruptly incurved at a right angle, and enlarged at the height of the angle; head with short dorsal and longer ventral chamber.

Measurements. Body (N=5): total length 125−135 µm, toe 25−26 µm; trophi (N=5) ~20 µm, ramus ~6 µm, fulcrum 5 µm, uncus 7.2 & 8.0 µm, manubrium 12.6 & 14 µm.

Comments. Proales francescae sp. nov. belongs to the Proales reinhardti (Ehrenberg, 1834) group. It can be confused with P. halophila Remane, 1929 , which shows a more vase-shaped trunk, narrower head, less drawn out toes, and lacks the indentations near the base of the tail. It may safely be distinguished by the trophi which in P. halophila (see De Smet 1996a) show only two alulae, and a single crenate crest of fused elements on the left ramus, and three on the right ramus. The caudae are smoothly incurved and gradually tapering in P. halophila , instead of incurved at a right and slightly enlarged angle in the new species. Proales francescae sp. nov. bears some resemblance with the species described as P. halophila by Tzschaschel (1979), but can not be compared seeing the poor and unreliable trophi description not based on SEM, imperative for the small Proales species.

Distribution and ecology. Proales francescae sp. nov. was collected in sublittoral psammon from the Costa Brava, Golfe du Lion, Côte d’Azur and Elba Island, from 20 m up to 8 km off shore, depth 15−50 m, June, July, September, October, 17−22 °C. The species was previously reported sub Proales sp. from Aufwuchs of a stand of brown algae in the sublittoral fringe of Grande Anse, Réunion Island, Indian Ocean (De Smet 2006).

Figures

FIGURE 20. Proales francescae sp. nov. A. Female, dorsal; B. foot and toes, dorsal; C. trophi, complete set, ventral; D. detail incus and unci. Scale bars: A: 50 µm; B − D: 10 µm.

FIGURE 21. Proales francescae sp. nov., SEM photographs of trophi. A. Complete set, ventral; B. detail, ventral; C. detail, dorsal; E. detail, lateral. Scale bars: 10 µm.