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SYNCHAETIDAE, (REMANE, 1933) (family)
Jaws (trophi) symmetrical. Jaws virgate.
All four part present, fulcrum is long, asymmetric and the rami pointed. Piercing and sucking.

POLYARTHRA, EHRENBERG 1834.
Without foot. Cuticle thin, transparent,
not usually retaining its shape well after preservation.
Body with 12 blades or feathers in 4 groups of 3 blades,
groups dorsoventrally and 2 groups ventrolatterally.
Planktonic.

66 a. Blades serrated sword-shaped, only up to 15 μm broad.
Length of blades longer than length of body
Size 90-120 μm. Ventral finlets present
(can only be seen for sure in lateral view.)
- IRRI rice field.
   Polyarthra cf. dolichoptera IDELSON, 1925
      [1999]

66 b. Blades feather-like, up to 30 μm broad
(should be measured by a micrometer on a flat blade.)
Length of blades equal to or less than body length...67

67 a. Blades 20-30 μm broad. Length of blades
less than length of body.
No ventral finlets. Size 150-170 μm.
- Lake Danao.
   Polyarthra major, BURCKHARDT, 1900
      [1999]

67 b. Blades 8-20 μm broad, but variable, grading
from father-shape to narrow sword-shape
(narrowing the P. dolichoptera shape).
Length of blades equal to or less than body length.
Ventral finlets present. Size 100-150 μm.
Feeds only on algae (Diatoms and Cryptomonads,
as in Lake Lanao (Lewis 1979)). Planktonic in lakes,
eurytherm, in oxygenrich waters.
- Laguna de Bay, Pasig River, La Mesa Dam, Lake Mainit,
  Lake Lanao, Paoay Lake.
   Polyarthra vulgaris, (CARLIN, 1943)
      [1973, 1977, 1978a,b, 1979b,
       1980, 1984, 1986, 2008b, 2009]

P. vulgaris from Laguna de Bay

 

To 68 a.