Testudinella clypeata (Müller, 1786), Muller, 1786

De, Willem H., 2009, A review of the marine and brackish-water species of Testudinella (Rotifera: Monogononta, Testudinellidae), with the description of two new species, Zootaxa 2092, pp. 1-20 : 11-13

Testudinella clypeata (Müller, 1786)

( Figs 8–10 )

T. clypeata typica after Voigt (1957), T. elliptica after Jersabek et al. (2003, ANSP Catalog Number 1828)? non T. clypeata after Rousselet (1898), Dieffenbach & Sachse (1912) and Bartoš (1951, Figs 7 , 8 ), T. crassa after Harring (1913), T. clypeata var. crassa after Remane (1929) and Voigt (1957), T. clypeata crassa after Wiszniewski (1954) and Bērziņš (1960)

non T. clypeata after Bartoš (1951, Figs 3 , 4 ), T. clypeata dentata after Wiszniewski (1954), T. clypeata f. pseudoclypeata Koste (1978)

This species is easily recognized by the elliptical lorica (length/width ratio 1.30–1.55, average 1.45), which is often slightly angular postero-laterally ( Figs 8 A, 9C) apparently depending on the state of contraction or fixation ( Fig. 9 ). The dorsal anterior margin is convex, and the ventral anterior margin shows a broad Vshaped sinus; a dorsal transversal fold is often present at the end of the lorica. In cross-sectional view ( Fig. 8 D–F) the dorsal margin appears convex, the lateral edges are broadly rounded and separated by a shallow sulcus from a convex median part ventrally. The characteristic foot-opening is a wide inverted U-shaped slit, situated ventral and sub-terminal. The foot ( Fig. 8 G) is composed of a long and wrinkled proximal part, a clearly offset slender distal pseudosegment and a less defined short penultimate pseudosegment. The dorsal and lateral antennae are situated somewhat posterior to the anterior third of the lorica: ratio lorica length/ position of antenna(e) relative to antero-dorsal margin varying from 2.70–2.85 (average 2.75) and 2.35–2.75 (average 2.58) respectively. Two red eyespots.

The trophi ( Fig. 10 and De Smet (2005)) are characterized by 14–16/14–16 (left/right) unci teeth. The three major teeth show a slender and distinctly offset head. The manubria are composed of three large superimposed chambers, the dorsal, median and ventral, and a strongly reduced sub-ventral chamber ( Fig. 10 B: sc). About 28–30/25–26 arched rami scleropili are apparent in caudal view. The fulcrum shows a distinct proximal opening frontally ( Fig. 10 : fo).

Measurements. Lorica length 150–170 µm, lorica width 100–130 µm, distal foot pseudosegment 18–22 µm.

According to De Ridder & Segers (1997), T. clypeata is a widespread species occurring in the marine littoral and brackish waters all over the Palaearctic region. The species has apparently often been confused with T. elliptica , however, the reliable illustrated records by De Manuel et al. (1992), De Maeseneer (1980), De Ridder (1957a, b, 1967, 1972), Gillard (1947), Hudson & Gosse (1886), Seehaus (1930), von Hofsten (1911), Wulfert (1942) and personal observations confirm this general distribution. The reports from freshwater habitats are probably misidentifications concerning T. elliptica . De Ridder & Segers (1997) also report the species from the Nearctic region (Cap Breton Island, Nova Scotia, Canada), incorrectly referring to Chengalath & Koste (1988). However, the specimens mentioned sub T. elliptica by Jersabek et al. (2003; ANSP Catalog Number 1828) and originating from a brackish pool near Atlantic City, New Jersey, USA are distinctly T. clypeata , illustrating the species’ presence in the Nearctic.

Figures

FIGURE 3. Testudinella bicorniculata sp. nov., scanning electron microscope photographs of trophi. A. Complete set, frontal view. B. Complete set, caudal view. C. Complete set, lateral view. D. Detail proximal fulcrum opening and basal apophyses. E. Detail left ramus with arched scleropili. Scale bars 10 µm. a: alula, as: arched scleropili, ba: basal apophyses, dc: dorsal chamber, fo: fulcrum opening, mc: median chamber, sc: sub-ventral chamber, vc: ventral chamber

FIGURE 4. Testudinella elongata sp. nov. A. Lorica, dorsal view. B. Lorica, ventral view. C. Lorica, cross-sectional view. D. Foot pseudosegments. Scale bars A – C: 50 µm, D: 25 µm.

FIGURE 7. Testudinella obscura, scanning electron microscope photographs of trophi. A. Complete set, frontal view. B. Detail left manubrium. C. Complete set, caudal view. D. Complete set, lateral view. Scale bars: 10 µm. a: alula, dc: dorsal chamber, fo: fulcrum opening, mc: median chamber, sc: sub-ventral chamber, vc: ventral chamber.

FIGURE 8. Testudinella clypeata. A – C. Loricae, ventral view. D – F. Loricae, cross-sectional view. G. Foot pseudosegments. Scale bars: A – F: 50 µm, G: 25 µm.

FIGURE 9. Testudinella clypeata, variation in shape of specimen. A, B. Contracted. C. Swimming. Scale bar: 50 µm.

FIGURE 10. Testudinella clypeata, scanning electron microscope photographs of complete set of trophi. A. Frontal view. B. Caudal view. Scale bar: 10 µm. fo: fulcrum opening, sc: sub-ventral chamber.