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QUADRATA GROUP
Insertion of posterior spines at the posterior corners.

 

50 a. Dorsal plate of lorica with 2 closed median
        fields and one open. Left lateral posterior
        spine always present. Size 150-300 μm.
        Very polymorphic. Feeds mainly on unicellular
        algae less than 10 μm. In large lakes with
        long spines (form frenzeli), or in ponds

        with thick lorica covered with spines. Indicator
        of mesotrophic waters (Sládeček (1983).
        - Laguna de Bay (?), Pasig River, Calibato Lake.

           Keratella quadrata, (MULLER, 1786)

(syn. Anureae aculeata)

           [1941a, 1974, 2009a]

K. quadrata from Calibato Lake

50 b. Dorsal plate of lorica with 3 closed median fields.

      Left lateral posterior spine more or less reduced...........51

 

51 a. Third median field hexagonal, closed by a trans­verse
ridge. Size 250 μm. Dorsal plate of lorica with 5
clear marginal facets (f. valga[1] lack or has very
indistinct marginal facets. Left lateral posterior
spine reduced (form typica), strongly reduced (form
assymmetrica).Left lateral posterior spine reduced
(form typica), strongly reduced (form assymmetrica)
or absent (form monstrosa). Planktonic in tropical
lakes, warm-stenotherm. Affected negatively by bloom
of green algae Botryococcus braunii blooms in Paoay
Lake (Papa et al., 2007a, 2008d: record of T. procurva
is re-determined to T. tropica, Aquino et al., 2008b).
Abundance was higher in the Northern basin of Taal Lake,
than the Southern basin, probably caused by the
eutrophication effect af the fish gages in the area
(Papa et al. 2011b).
- Laguna de Bay, Pasig River, Paoay Lake, Bunot Lake,
  Calibato Lake, Tadlac Lake, Taal Lake, Lake Mainit, Lake Lanao,
  IRRI rice field, Lake Danao(Leyte/Cebu?).

Keratella tropica (APSTEIN, 1907)
(syn. Keratella valga tropica).
           [1941a (valga + tropica), 1973, 1974 (valga),
           1980, 1984a, 1999, 2008b, 2009a, 2001a,
           2011a (valga valga), 2012a]

 

K. tropica from Laguna de Bay

51 b. Third median field pentagonal, terminating in
a median ridge. Posterior spines divergent of
unequal length. Shows affinity for the cyanobacteria
(blue green algae) and dinoflagellates in Lake Lanao
(Lewis 1979). In ponds, ricefields, and lakes. Rare.
- Lake Lanao, Laguna Lake, IRRI rice field, Taal Lake.
    Keratella procurva (THORPE, 1891)
              [1977, 1978a+b, 1979b, 1986a, 1999, 2001, 2007a,
               (2008d T. tropica, Aquino et al., 2008b),
               2001a, 2009a, 2011a)]

  

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[1] K. valga is accepted as a separate species by some authors (E.g. Fernando 2002a).
K. valga is thus distinguished from K. tropica by lack of or with very indistinct
5 clear marginal facets.

 

 

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