A review of the marine and brackish-water species of Testudinella (Rotifera: Monogononta, Testudinellidae), with the description of two new species Author De, Willem H. text Zootaxa 2009 2092 1 20 journal article 10.5281/zenodo.187516 aa61272c-ae6b-4bc6-89f8-19b912abd2eb 1175-5326 187516 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) 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. 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). 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. 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.