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A new, weighted matrix identification key for 34 largely undisputed species of Synchaeta was created with the aim of providing comparable, detailed and diagnostic character sets for each species that can be applied to live and/or preserved specimens. As part of this process, 14 species of Synchaeta were intensively re-investigated with respect to their habitus and trophi morphology using binocular, light, and scanning electron microscopy, which, together with behavioural observations, revealed several new discriminating characters. Whenever possible, missing information for any character was added for the remaining species from the literature, with the two recently described species Synchaeta arcifera and Synchaeta squamadigitata being considered for the first time in an identification key. Beyond its completeness, our key has two distinct advantages. First, the characters are supported by detailed illustrations of their respective character states whenever possible to both simplify identification and minimize any uncertainty in the descriptions themselves. Second, the new approach of weighting the characters according to their reliability, robustness and/or ease of determination was employed. This latter approach is especially advantageous for soft-bodied rotifers such as species of Synchaeta, where, for example, several external characters can be influenced by preservation and are therefore less diagnostic or reliable. Although the key is as comprehensive as possible, information for many species remains missing for many characters, thereby highlighting the need for additional comprehensive and detailed species (re-)investigations within Synchaeta.

Wilke, Tanja, Ahlrichs, Wilko H., Bininda-Emonds, Olaf R. P. (2017): A comprehensive and integrative re-description of Synchaeta tremula (Müller, 1786) and the newly rediscovered Synchaeta tremuloida Pourriot, 1965 (Rotifera: Synchaetidae). Zootaxa 4276 (4): 503-518, DOI: https://doi.org/10.11646/zootaxa.4276.4.3

Trophi of S. tremula and S. tremuloida The following is a morphological description of the trophi of both S. tremula and S. tremuloida, which are virtually identical except for peculiarities of the frontal hook and the extension of the cauda tip. The trophus elements comprise a single elongated and dorsally bending fulcrum, extensive paired ventral rami, an unpaired ventral hypopharynx, two extensive paired dorsolateral manubria with elongated cauda, and paired apical unci. The trophi of both species are of the virgate type, which Koste (1978) has further subdivided within Synchaeta into the Synchaeta-pectinata- type, which exhibits unci with a frontal hook and no further teeth, and the Synchaeta-tremula - type, which exhibits unci with at least one frontal hook and several distinctly incised teeth. The trophi of both S. tremula and S. tremuloida belong to the Synchaeta-tremula -type. Unci. The paired unci are located immediately behind the mouth. They are connected to the rami and manubria by ligaments and are characterized by exhibiting hooks and several unci teeth. Two frontal hooks are present per uncus, of which the dorsal one is noticeably larger (Fig. 4 E, J; dfh). A triangular platelet of numerous piliform and sclerotized processes connects each dorsal frontal hook of an uncus with the ipsilateral manubrium (Fig. 4 E, J; tp). The ventral frontal hook is slightly broader and distinctly blunter in S. tremuloida than in S. tremula, where it is thin and sharp (Fig. 4 E, J; vfh). A distinct gap is present between the ventral frontal hook and the unci teeth. The unci are slightly asymmetric, with seven and six teeth being typical of the right and the left uncus, respectively (Fig. 4 D, I; un). The teeth are all distinctly incised and separated by a deep sulcus into dorsal and ventral groups of three except for the dorsal group on the right uncus which has four teeth. Occasionally (ca. 10%), the unci of either species also possess 5���6 teeth on the right side and 4���5 on the left. In such cases, the ventral tooth-group that normally consists of three teeth is fused into two teeth or one large, blunt tooth. Rami. Because no evidence of any chamber openings was observed, the rami would appear to lack the basal and sub-basal chambers that are otherwise typical of the rotifer ramus. Instead, like the rami of other Synchaeta species, those of S. tremula and S. tremuloida are built up of two extensive lamellae that converge distally at the proximal end of fulcrum. The inner side of each ramus is raised and robust. Both inner reinforcements of the rami jointly form a triangular shape that demarcates the median interspace between both lamellae (Fig. 4 A, F; rir). An additional robust ridge originates from each uncus to span the median portion of each lamella (Fig. 4 A, F; rmr). Another strong, short ridge is located distally, reinforcing the distal part of each lamella (Fig. 4 A, F; rdr). The remaining parts of the rami are more finely structured. The margin of each ramus is rounded outwardly and exhibits a distinct indentation distally at the proximal end of the fulcrum. Hypopharynx. The hypopharynx is an unpaired trophus element that is located ventral to the apical part of ramus. The apical part of the hypopharynx is composed of a horizontal joist that is raised centrally (Fig. 4 C, H; hyp), is of medium width, and exhibits pointed lateral ends. The caudal part of hypopharynx comprises a semicircular and fine structure attached to apical joist (Fig. 4 A, F; hyp). Fulcrum. The fulcrum is an unpaired element that arises ventrally from the distal ramus and bends towards the dorsal side of the animal at an angle of 135�� (Fig. 4 C, H; fu). It is blade-shaped in lateral view and decreases slightly in width moving distally. Distinct longitudinal ridges, as sometimes found in the fulcra of other Synchaeta species (e.g. Synchaeta grandis; pers. obs.), were never observed. Manubria. The paired manubria, like those of other Synchaeta species, apparently lack the dorsal, median and ventral manubrial chambers. Each manubrium is composed of an extensive, round, but fine lateral clava (Fig. 4 B, G; cl), a distinct dorsoventrally curved and robust cauda (Fig. 4 C, H; ca) and a medially directed, triangularly shaped toothlike clava lamella (Fig. 4 B, G; clt); all these components encompass the lateral and, in part, the dorsal trophus regions (Fig. 4 B & C, G & H). The cauda extends beyond the clava distally by one-third of the overall cauda length. In S. tremula, this extension of the cauda tip is blunt and narrow, whereas it is broadened in S. tremuloida (Fig. 4 C, H; ca). Molecular analysis. Genetic distances for both COI and 18S revealed patterns of little to no intraspecific variation within each of S. tremula and S. tremuloida compared to large interspecific variation between the two species (see Table 2). Results from the popDiversity.pl analyses revealed that the maximal observed intraspecific variation for either species never overlapped with the minimal interspecific variation, with the minimal bar-coding gap being 2.9x (COI for S. tremula versus the interspecific distance). This pattern is likewise found in the haplotype network for each gene, with the two species being separated by either 10 mutations for the more slowly evolving 18S or 80 mutations for the more quickly evolving COI (Fig. 5). In most cases, only a single haplotype was present for both S. tremula and S. tremuloida for each gene with the exception of S. tremula for COI where eight haplotypes were divided into three linearly arranged clusters separated by a high number of mutations (38 and 56). Finally, all three species demarcation analyses (Fig. 6) supported that both species form well separated, reciprocally monophyletic clades with respect to one another for each gene. Again, evidence for additional, ���significant��� sequence divergence within S. tremula is indicated for COI, with the different methods indicating the existence of up to five separate species within this clade., Published as part of Wilke, Tanja, Ahlrichs, Wilko H. & Bininda-Emonds, Olaf R. P., 2017, A comprehensive and integrative re-description of Synchaeta tremula (M��ller, 1786) and the newly rediscovered Synchaeta tremuloida Pourriot, 1965 (Rotifera: Synchaetidae), pp. 503-518 in Zootaxa 4276 (4) on pages 512-513, DOI: 10.11646/zootaxa.4276.4.3, http://zenodo.org/record/807901, {"references":["Koste, W. (1978) ROTATORIA. Die Radertiere Mitteleuropas, begrundet von Max Voigt. Uberordnung Monogononta. Gebruder Borntraeger, Berlin, Stuttgart, 673 pp."]}

Pleurotrocha petromyzon (Ehrenberg, 1830) (Notommatidae) Notommata petromyzon Ehrenberg, 1830 Notommata gibba Ehrenberg, 1832 Notommata petromyzon: Ehrenberg 1838 Proales petromyzon: Hudson & Gosse 1886 Notops laurentinus Jennings, 1894 Proales laurentius Jennings, 1896 Pleurotrocha laurentina: Harring 1913 Diagnosis. Species with fusiform, stout body; toes short and conical; retrocerebral organ with posterior sphere followed by dark red eye; large gastric glands with 9 nuclei; large pedal glands extending into trunk; triangular rami with rounded alulae; manubrium with large, lateral, knob-like protuberance; crescent-shaped unci with 2 large and 3 minor uncinal teeth; end of distal fulcrum flattened and arched dorsally. General body organization of parthenogenetic females Habitus (Figs 5 A, B, 6 A���C, 7 A���E). Body stout, fusiform, hyaline, divided into 3 distinct regions: head, trunk and foot with toes. Epidermis hardly stiffened, with smooth surface. Head sloped, contractile and offset from trunk by weakly developed neck fold. Corona extending between apical and ventral head region, characterized by dense pseudotrochus of locomotory cilia. Pseudotrochus merges ventrally with cilia field running to mouth opening. This restricted posteriorly by paired lobe-like epidermal projection (Fig. 7 E). Locomotory cilia enclosing apical field on head; middle of apical field with 2 openings of retrocerebral organ. Trunk arched dorsally, much wider than head (Figs 5 B, 7 B), and comprising 3 pseudosegments. First pseudosegment large, followed by narrower, shorter lumbar pseudosegment and preanal pseudosegment. Foot retractile, tapering conically, divided into 2 pseudosegments and 2 relatively short, pointed, conical toes (Figs 5 A, 7 B), directed caudally during swimming process. Terminal foot pseudosegment twice length of first one. Digestive system (Figs 5 A, B). Mouth opening in ventral part of corona leads to short, slender, ciliated buccal tube that discharges ventrally to spherical mastax. Oesophagus diverges from anterior third of mastax dorsally. Stomach multicellular, ciliated, with yellow-brownish, small and large egg-shaped droplets, occupying one-third of trunk (Fig. 6 A). Ciliated intestine offset from stomach. Anus discharges below preanal pseudosegment. Trophi (Figs 5 C, D, 9 A���D). Trophi virgate, bilaterally symmetrical with fulcrum residing almost in longitudinal axis of body. Rami. Stout, in ventral view appearing triangular, arched upward anteriorly in sickle-shaped bend (Fig. 10), inner margins with fine denticles (Fig. 5 C). Ramus foramen subbasalis small, somewhat circular (Figs 5 C, 9 C), directed ventrally. Ramus foramen basalis large, ovate, directed dorsally. Rami with broad, acuminate alulae distally (Figs 5 C, 9 A). Fulcrum. Long, rod-shaped, longitudinally striate; in ventral view slender, expanding distally; in lateral view flattened and curved upward distally. Unci. Slightly curved plates, with 2 ventral and 3 more dorsal principal teeth; ventral and dorsal tooth group separated by triangular gap (Fig. 5 D, 9 D). Manubria. Slightly curved, tapering gradually from broad basal clava to distal end of long, rod-shaped cauda. Clava composed of 3 chambers that are not clearly distinguishable but show distinct openings. Ventral manubrial chamber with small, rounded, ventrally directed opening and features a small, knob-like protuberance (Figs 5 C, D, 9 B) ventrolateral to median chamber of manubrium. Median manubrial chamber forms elongated cauda and shows small, oval, ventrolaterally directed opening (Fig. 9 B). Small dorsal manubrial chamber opens dorsolaterally, with ovate opening. Hypopharynx. a fork-like structure at the proximal end of the fulcrum (Fig. 9 A). Nervous system and sensory organs. Cerebral ganglion rounded, extending to centre of head, followed by large, reasonably hyaline retrocerebral organ that cannot be discriminated from brain by light microscopy. A dark-red kidney-shaped eye present at posterior end of retrocerebral organ (Fig. 10). A fine connection inserts close to eye and courses down to mastax (Figs 5 A, 6 A). Dorsal antenna consists of several cilia encircled by flat, rounded collar located in front of head fold (Fig. 7 D). Lateral antennae comprising a few cilia, with a flat, rounded collar, located just beyond midpoint of trunk. Glandular system (Figs 5 A���B, 6 B). Two lateral salivary glands visible, integrated into mastax complex. Both gastric glands large, ball-shaped, unstalked, with 9 nuclei each, diverging anteriorly from stomach. Retrocerebral organ lies behind cerebral ganglion and opens with 2 anterior ducts on apical field of corona (Fig. 10). In posteriormost region of retrocerebral organ, and immediately in front of the eye, is a vesicle-filled sphere. Pedal glands extend into preanal pseudosegment, with terminally constricted mucus reservoir above toes. Protonephridial system (Figs 5 A, B). Protonephridia paired, with distinct terminal organs (exact number and position not determined). Collecting tubules open into contractile bladder that in turn empties into terminal part of intestine (cloaca). Reproductive system (Figs 5 A, B, 6 A, B). Germovitellarium unpaired, with 8 nuclei, located in the ventral region of trunk, often associated with a large, dark egg. Measurements. Total length 150���255 ��m, maximum dorsoventral extent 70 ��m, maximum width 60���80 ��m, foot length 28 ��m, toe length 12���26 ��m, trophi length 35 ��m, ramus length 16 ��m, manubrium length 21 ��m, manubrium width 7 ��m and fulcrum length 24 ��m. Ecology. The species is limnosaprobic and free-living, occurring in running, acidic, brackish water and is present in both colder and warmer seasons. Distribution is cosmopolitan (Nogrady et al. 1995). The species is necrophagic and includes smaller sessile peritrich ciliates in its diet, especially Carchesium. Several generations, including juveniles and eggs, often live on a single ciliate colony (Figs 6 C, D). In one instance, six specimens were observed living on a single Carchesium colony. Specimens are well protected in the colony, which encloses the rotifers following disturbances. Feeding specimens attach with their pedal glands, stretch and approach the body of an individual ciliate. The ciliate is eaten completely, leaving only its stalk (Figs 6 A, 8 B). Usually 2��� 3 eggs are deposited and fixed to the substratum, with a stalk formed by an adhesive secretion from the pedal glands (Fig. 6 D). Smooth (Fig. 7 F) as well as sculptured eggs (Fig. 8 A) were found. Specimens were also found in the middle of stalked ciliates growing on Macrocyclops. Ehrenberg (1838) reported the species on Epistylis digitalis, Carchesium polipinum, Zoothamnium and piercing Volvox globator. Budde (1925) also found specimens in Volvo x and in the shells of dying and dead crustaceans (Daphnia, Chydorus, Entomostraca), where they always feed towards the head, deposit 2��� 3 eggs and then leave the individual. The species was also found on trichopteran eggs, on Hydra (De Beauchamp 1905) and on snail eggs (Wulfert 1935)., Published as part of Wilts, Eike F., Bininda-Emonds, Olaf R. P. & Ahlrichs, Wilko H., 2009, Comparison of the predatory rotifers Pleurotrocha petromyzon (Ehrenberg, 1830) and Pleurotrocha sigmoidea Skorikov, 1896 (Rotifera: Monogononta: Notommatidae) based on light and electron microscopic observations, pp. 1-20 in Zootaxa 2130 on pages 7-13, DOI: 10.5281/zenodo.188361, {"references":["Ehrenberg, C. G. (1830) Organisation, Systematik und geographisches Verhaltnis der Infusionsthierchen. Abhandlungen der koniglichen Akademie der Wissenschaften zu Berlin gehalten in den Jahren 1828 u. 1830, 1 - 108.","Ehrenberg, C. G. (1832) Uber die Entwicklung und Lebensdauer der Infusionsthiere, nebst ferneren Beitragen zu einer Vergleichung ihrer organischen Systeme. Abhandlungen der koniglichen Akademie der Wissenschaften zu Berlin, 1 - 154, pl. 1 - 4.","Ehrenberg, C. G. (1838) Die Infusionsthierchen als vollkommende Organismen. Ein Blick in das tiefere organische Leben der Natur. Leopold Voss, Leipzig, 548 pp.","Hudson, C. T. & Gosse, P. H. (1886) The Rotifera or Wheel-Animalcules, both British and foreign. London. Vol. 1, vi, 128 pp., Vol. 2, 144 pp.","Jennings, H. S. (1894) A list of the Rotatoria of the Great Lakes and some of the inland lakes of Michigan. Bulletin of the Michigan Fish Commission, 3, 1 - 34.","Jennings, H. S. (1896) Report on the Rotatoria with description of a new species. Bulletin of the Michigan Fish Commission, 1896, 1 - 9.","Harring, H. K. (1913) Synopsis of the Rotatoria. Bulletin of the United States National Museum, Washington 81, 7 - 226.","Nogrady, T., Pourriot, R. & Segers, H. (1995) Rotifera 3: Notommatidae and Scaridae. In: T. Nogrady & H. J. Dumont (Eds.), Guides to the Identification of the Microinvertebrates of the Continental Waters of the World, 8. SBP Academic Publishing b. v., Amsterdam, New York, 248 pp.","Budde, E. (1925) Die parasitischen Radertiere mit besonderer Berucksichtigung der in der Umgebung von Minden I. W. beobachteten Arten. Zeitschrift fur Morphologie und Okologie der Tiere, 3, 706 - 784.","De Beauchamp, P. (1905) Remarques sur deux Rotiferes parasites. Bulletin de la Societe zoologique de France, 30, 117 - 124.","Wulfert, K. (1935) Beitrage zur Kenntnis der Radertierfauna Deutschlands. I. Teil. Archiv fur Hydrobiologie, 2, 583 - 602."]}

Cephalodella ungulata n.sp. (Figures 1���4) Material and methods: Live samples were taken form the type locality. After extensive examination of the living individuals, some individuals were taken for the trophi preparation (after De Smet 1998 a) but with SDS/DTT (modified after Kleinow et al. 1990, without proteinase K). Other specimens were narcotized with carbonated water and fixed with Picricacid formaldehyd, 240 mOsm (after Melone 1998). Dehydration was carried out in a graded ethanol series followed by critical point drying. Scanning electron microscopy was performed with a Zeiss DSM 940, operated at 10 kV. Holotype: A parthenogenetic female in a permanent, glycerin glass slide mount deposited at Museum f��r Naturkunde, Berlin, (ZMB) Generalkatalog freilebende W��rmer ZMB Vermes 11217. Paratypes: Two parthenogenetic females mounted for SEM deposited as ZMB Vermes 11218 ��� 11221 (two individuals from other species on this stub) and a trophi preparation with SDS/DTT for SEM with four trophi as ZMB Vermes 11222���11225 deposited at ZMB, Germany. Type locality: A ditch near Leer Lower Saxony, Germany. November 2005 (53 �� 14 ��� 25.82 ��� N, 7 �� 31 ��� 15.88 ��� E). Diagnosis: Short claw-bearing toes, usually slightly retracted, approximately 1 / 5 of the total length and bent dorsally; double keeled tail; hyaline, without eyespots or lenses; trophi type D (after Wulfert 1937 & 1938) with asymmetrical unci with two uncinal teeth and a toothlet on the left and one uncinal tooth on the right uncus; three pairs of salivary glands: one lateral (small), one ventral and one dorsal (both large). Description: Habitus (Fig. 1 & 4): Elongate, slightly laterally compressed body with hyaline soft lorica and ill-defined plates. Head set off. Short dorsally bent toes bearing claws usually slightly retracted. They are approximately 1 / 5 of total length. Convex corona nearly terminal and without lips. Head and foot relatively long in comparison to trunk. Double-keeled tail nearly covers foot. Corona: Nearly terminal, convex. Dorsal antenna-bearing pseudosegment: Rectangular, dorsal antenna near caudal margin. A fold as continuation of lateral sulcus of trunk. In SEM two parallel folds on either side of dorsal and ventral median line. Distinct constriction between dorsal antennabearing segment and trunk. Trunk pseudosegment: Widening towards lateral antennae in dorsal or ventral view. Lateral antennae in caudal third of trunk. Dorsally with wide sulcus. Lateral sulcus narrow and difficult to observe in a light microscope. Tail: Nearly covering foot laterally and posteriorly. Delimited from foot and trunk. Double keel as continuation of dorsal sulcus of the trunk. Foot pseudosegment: Dorsally and ventrally nearly parallel-sided. Towards trunk narrower than tail from the side. Inconspicuous groove between toes. Toes: Approximately 1 / 5 of total length, usually slightly retracted, continuously tapering to tip, with septum near tip and claws. Lateral view: dorsally bent; dorsal view: toes a little bit apart, proximal parts slightly convergent but tips divergent; toes a little bit narrower than when viewed from the side. Digestive system (without trophi, Fig. 1 B & 1 D): Mouth opening in beginning of ventral part of corona. Ephipharynx consists of two pairs of rod like structures, one pair shorter than the other. Mastax length roughly �� of dorsal antennae-bearing segment with three pairs of salivary glands: two large pairs dorsally and ventrally and one smaller pair laterally. Oesophagus clearly visible. Stomach cells with small inclusions. Stomach after �� of trunk continued by small intestinum. Stomach sometimes coloured yellow. Anus directly under tip of tail. Trophi (Fig. 2 & 3): Tilted against body axis by angle of roughly 30 �� with fulcrum pointing ventrally. ���Fulcrum: Lateral view: dorsally straight, ventrally broadening towards rami, rodlike in middle and spatulate at caudal end; with basal apophysis. Dorsal view: rodlike, spatulate at caudal end. ���Rami: With conspicuous ridges. Frontal median margin with toothlike lamella. Ventral caudal margin nearly rectangular to fulcrum. Behind dorsal and lateral margin subunci. 6���7 smaller teeth follow one large tooth on each inner margin of subbasalchambers. ���Manubria: Clava with two lamellae: ventral one broadening towards cauda of manubria and with wide opening; dorsal one first broad, then tapering towards cauda of manubria and without opening. Medium rodlike part with opening. Cauda broader than medium part of clava at base and narrowing towards end. Caudal end curved ventrally with tip tilted dorsally and inwards. ���Unci: Two uncinal teeth one after another and a toothlet above them on left uncus with a gap between these in which the right uncinal tooth fits (Fig 2 E & 3), both unci with broad lamellae. Musculature (not figured): Some parts of ring-muscles and some retractors in front region visible. Epidermis: Without secondary structure; smooth and hyaline. Glands (Fig 1 B & 1 D): Two large oval pairs of salivary glands dorsally and ventrally of mastax with smooth surface. Additionally, one pair of small round salivary glands laterally of mastax. Gastric glands nearly round and short stalked. A pair of subcerebral glands present. Footglands large: approximately 1 / 3 of foot. Nervous system and sense organs: Large ganglion, one part innervating dorsal antenna, with a pair of small subcerebral glands. No eyespots. A small round retrocerebral organ at the end of ganglion visible. Dorsal antenna near caudal margin of dorsal antennabearing segment, consisting of a small number of cilia (Fig 4 B). Lateral antennae consisting of two diverging cilia inserted in caudal third of trunk (Fig 4 A). Between retracted toes a very small caudal antenna with only one cilium visible with SEM (Fig. 4 D). Reproductive system (Fig 1 B & 1 D): Vitellarium with eight nuclei. Parthenogenetic egg oval and parts of it in foot and tail. Protonephridial system: Fluid of protonephridial bladder is emptied into the terminal portion of intestinum (cloaca). Differential diagnosis: The three taxa with reportedly type B trophi but a manubrial end similar to the new species show otherwise clear differences to the new species. The body of C. boettgeri is reminiscent of C. gibba (Ehrenberg). The plates are not discernable, the toes are tapering uniformly and only four salivary glands are reported. C. lindamaya has characteristic toes with fairly large terminal claws. These claws are curved with acute tips and four distinct spinules are inserted in a row on the inner edge of the claw. The habitus of C. theodora is much more compact and the toes are shorter and of a characteristic shape. Only three of the seven species with type D��� C. tenuiseta, C. stenroosi Wulfert, 1937 and C. gigantea Remane, 1933 ��� have no eyspots as is the case in the new species. But C. stenroosi and C. gigantea show clear differences in habitus to the new species. This for example is seen in the toes, which are much longer in C. gigantea and in C. stenroosi have a dorsal lump (also in the older synonym C. bertonicensis Manfredi, 1927) or a blunt tooth in the middle, so there is no confusion possible. However, Donner (1972 & 1978) described the variant C. stenroosi austriaca with smooth toes. As far as the salivary glands lacking as in C. stenroosi and the tophi (Fig. 5) are concerned, this variant can easy be distinguished from C. ungulata n. sp. The new species differs from C. tenuiseta in morphology and relative position of the toes. In C. tenuiseta the toes are closer together, thinner, longer and without claws. Additionally, the trophi of C. ungulata n.sp. differ from those in C. tenuiseta in having asymmetrical unci with two uncinal teeth on the left and one on the right uncus. The variation americana has been described by Donner (1950) who considers the earlier descriptions of C. tenuiseta by Harring & Myers (1924) and Wulfert (1937) to be other descriptions of this variation. But they vary in the description of trophi, toes and body shape. Harring & Myers (1924) variation americana was found in brackish and saltwater ditches ��� a habitat completely different from habitats reported by other authors and also not the habitat of the new species. They found no retrocerebral organ such as we found in the new species. Unfortunately they give no figure of the trophi. The proportions and shape of the pseudosegments as given by Wulfert (1937) are almost identical to our new species. However, the species described by Wulfert (1937) is characterized by a shorter, not double keeled tail and a more convex corona. On the inner margin of the rami one large tooth is followed by ten to twelve smaller teeth as opposed to six to seven small teeth in C. ungulata n.sp. Furthermore, the basal apophysis of the fulcrum is lacking as well. The toes described by Donner (1950) are sturdier than those in the other descriptions of C. tenuiseta americana but still longer and closer together than in the new species. In this description, the right ramus bears a striped lamella and a single tooth, the left one two unequal teeth. This again is different from C. ungulata n.sp. where the inner margins of the rami are symmetrical. In C. tenuiseta americana the ends of the manubria are bent dorsally, whereas in C. ungulata n.sp. they are bent ventrally. All other species of the genus Cephalodella are clearly different from our new species. Measurements (n = 5): Total length 268���286 ��m, toe 51���59 ��m, trophi 34���40 ��m, Manubria ��m 29���32, Fulcrum 18���22 ��m. Distribution and ecology: Found in moderate numbers in the periphyton of a ditch with many plants near Leer, Lower Saxony, Germany (53 �� 14 ��� 25.82 ��� N, 7 �� 31 ��� 15.88 ��� E). This ditch with neutral pH harbours a great diversity of rotifers such as C. ventripes (Dixon-Nuttall), C. intuta Myers, Lophocaris oxysternon (Gosse), L. salpina (Ehrenberg), Mytilina trigona (Gosse), M. ventralis (Ehrenberg), Itura aurita (Ehrenberg), Dicranophoroides caudatus (Ehrenberg), Trichocerca tenuior (Gosse) and Plationus patulus (O.F. M��ller). The diet consists at least partly of autotrophic flagellates. Etymology: The species-name is derived from the Latin word ungula meaning claw because of the characteristic claws at the end of the toes. Discussion. Although C. ungulata n.sp. strongly resembles C. tenuiseta, it shows some clear differences in key diagnostic features such as trophi, toe-shape and relative toe length to C. tenuiseta. So it seems justified to give it the status of a new species and not only that of a variation of C. tenuiseta. It is not clear whether the old descriptions of C. tenuiseta by Burn (1890) and Dixon-Nuttall (1903) are only early descriptions of C. gigantea (Wulfert 1937, Nogrady et al. 1995). Given this, the variation americana would be the only description of C. tenuiseta and should be given species rank. But there is still the problem that the descriptions assigned to C. tenuiseta var. americana by Donner (1950) are considerably different. Harring & Myers (1924) found this species in brackish and saltwater ditches whereas the other two descriptors found it in freshwater. Therefore, it is unclear whether these can be the same species. Even the descriptions of Donner (1950) and Wulfert (1937) show clear differences in the shape of the toes and trophi, e.g. the inner margin of the rami and the presence or absence of a basal apophysis of the fulcrum. So can they be the same variation, are they different variations or are they even different species? This also applies to C. tenuiseta simplex Berzins, 1976. Answering this question, however, presupposes a careful re-examination such as De Smet (1998 b) carried out for C. catellina (O.F. M��ller) and related species., Published as part of Fischer, Claus & Ahlrichs, Wilko H., 2006, Cephalodella ungulata n. sp. (Monogononta: Notommatidae), a new rotifer species from North-West Germany, with notes on C. tenuiseta (Burn, 1890), pp. 49-59 in Zootaxa 1378 on pages 50-58, DOI: 10.5281/zenodo.175031, {"references":["De Smet, W. H. (1998 a) Preparation of rotifer trophi for light and scanning electron microscopy. Hydrobiologia 387 / 388, 117 - 121.","Kleinow, W., Klusemann, J. & Wratil, H. (1990) A gentle method for the preparation of hard parts (trophi) of the mastax of rotifers and scanning electron microscopy of the trophi of Brachionus plicatilis (Rotifera). Zoomorphology, 109, 329 - 336.","Melone, G. (1998) The rotifer corona by SEM. Hydrobiologia, 387 / 388, 131 - 134.","Wulfert, K. (1937) Beitrage zur Kenntnis der Radertierfauna Deutschlands. Teil 3. Cephalodellae. Archiv fr Hydrobiologie, 31, 592 - 636.","Wulfert, K. (1938) Die Radertiergattung Cephalodella Bory de St. Vincent. Bestimmungs- Schlussel. Archiv fr Naturgeschichte, 7, 137 - 152.","Remane, A. (1933) Rotatorien. In: H. G. Bronns Klassen und Ordnungen des Tierreichs Bd. 4 Abt. II Buch 1 Teil 1. 576 pp.","Manfredi, P. (1927) Prima nota intorna alla fauna della Gora di Bertonico. Bolletino di pesca, di piscicoltura e di idrobiologia Serie B (Suppl.) Memoria, 1, 1 - 58.","Donner, J. (1972) Radertiere der Grenzschicht Wasser - Sediment aus dem Neusiedler See. Sitzungsberichte der Osterreichischen Akademie der Wissenschaften, Mathematisch-Naturwissenschaftliche Klasse Abt. 1, 183, 131 - 148.","Donner, J. (1978) Material zur saprobiologischen Beurteilung mehrer Gewasser des Donausystems bei Wallsee und in der Lobau, Osterreich, mit besonderer Berucksichtigung der litoralen Rotatorien. Archiv fur Hydrobiologie (Suppl.) 52, 117 - 228.","Donner, J. (1950) Radertiere der Gattung Cephalodella aus Sudmahren. Archiv fur Hydrobiologie, 42, 304 - 328.","Harring, H. K. & Myers, F. J. (1924) The rotifer fauna of Wisconsin. II. Revision of the notommatid rotifers, exclusive of the Dicranophoridae. Transactions of the Wisconsin Academy of Sciences Arts & Letters, 21, 415 - 549.","Burn, W. B. (1890) Some new and little known rotifers. Science Gossip, London, 26, 34 - 37.","Dixon-Nuttall, F. R. (1903) The rotatorian genus Diaschiza: a monographic study with the description of a new species. Journal of the Royal Microscopical Society, 129 - 141.","Nogrady, T., Pourriot, R. & Segers, H. (1995) Rotifera 3: Notommatidae and Scaridae. In: T. Nogrady & H. J. Dumont (Eds.), Guides to the identification of the microinvertebrates of the continental waters of the world, 8. SBP Academic Publishing b. v., Amsterdam, New York, 248 pp.","Berzins, B. (1976) Notes on the rotifera from Aneboda, Sweden, private printing, Lund, p. 24.","De Smet, W. H. (1998 b) Cephalodella segersi n. sp. (Notommatidae, Monogonota), a new rotifer from Belgium, with notes on C. catellina (O. F. Muller, 1786), C. fluviatilis (Zavadovsky, 1926) and C. maior Zavadovsky, 1926 stat. nov. Hydrobiologia, 367, 1 - 13."]}