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ROTIFERA, Rotifers or Wheel animacules (phylum)

MONOGONONTA, WESENBERG-LUND 1899 (class).

PSEUDOTROCHA KUTIKOVA, 1970 (Superorder)

PLIOMA, HUDSON and GOSSE 1888 (order).

BRACHIONIDAE, HUDSON and GOSSE 1888 (family)

       Jaws malleate, planktonic as well as littoral species

BRACHIONUS, PALLAS 1766 

Foot and foot opening present (foot often retracted up into the body on formalin preserved specimens). Foot wrinkled, wormlike, long flexible and retractile. Lorica more or less flattened dorso-ventrally, with 2, 4 or 6 anterior spines and with posterior rounded or with 2 or 4 spines. Lorica absent, i.e. cuticle thin and flexible, not usually retaining its shape well after preservation. Large sack-shaped, with corona (wheel organ) interiorly. Rather big viviparous rotifers Planktonic family. Jaws incudate. Curved, sharp-pointed rami like pincers. Of seizing type. Intestine and anus absent. Rather thermophilic group, common in tropical waters (Segers 2001b). The genus is abundance among the plankton in polluted biotopes like Pasig River (2009a). Asplanchna releases a waterborne signal that induces spine formation in several Brachionus species (Snell, 1998). The presence of Asplanchna could then be responsible for the development of spines. Rather thermophile group, with several species in tropical waters (Segers 2001b), which may influence the interpretation of the Brachionus: Trichocerca quotient, QB/T, in tropical waters. Prefer alkaline waters (Sládeček 1983). Planktonic.

 

bach to 34a

35 a. 6 anterior spines on lorica.....................................36

35 b. Less than 6 anterior spines on lorica...........................37

 

36 a. Always 6 short, conical anterior spines on lorica. Body oval,
      slightly compressed dorsoventrally.

          URCEOLARIS GROUP............................................38

36 b. 6 long, pointed dorso-anterior spines on lorica, median 
      or rarely lateral spines longest.

          QUADRIDENTATUS GROUP........................................41  

 

36 c. Submedian spines longest (se 45a)...............................37


 

37 a. Always 4 pointed anterior spines of varying length and shape

present on lorica. Body sacciform.

          CALYCIFLORUS GROUP..........................................42

 

37 b. 2 small, pointed or blunt median anterior spines present, or,
      4 anterior spines present: 2 small, pointed median spines, and 2
        long, pointed lateral spines, or,
      6 anterior spines present, with 2 exceptionally long Submedian
        spines present (see 45a). Body oval, slightly
        compressed dorsoventrally.
          ANGULARIS GROUP.............................................43


To 38 a.