The corona is rather complicated. There is a circumapical ring which unlike that of Filinia longiseta possesses an underlip and the ciliation also covers the underlip. There are two trochal discs which are not very well pronounced. Cilia on the discs are longer than those on the circumapical ring. Mastax is malleoramate. There is a well developed, fulcrum which extends into two manubria. Two pronounced semicircular rami are present. The unci bear numerous teeth which extend up to the inner margin of manubria. (ref. ID; 3050)
Body cylindrical with two anterior spines which have broad bases. Anterior spines very long. The longer of the two posterior spines as long as the anterior spines. The smaller posterior spine about one-sixth of the longer posterior spine. Some individuals may have the posterior spines of approximately equal length. (ref. ID; 3180)
Measurements
Maximum body length 268; maximum breadth 71; length of the longer lateral spine 240; length of longer posterior spine 130; length of the shorter lateral spine 130; length of the shorter posterior spine 26 µm. (ref. ID; 3050)
This species is deviated from Filinia (s. str.) in having 1) two pairs (bigger and smaller) of gastric glands, 2) one pair of cloacal glands, 3) one pair of unknown glands at the base of caudal spines, 4) caudal sheath; and also in 5) the position of cloacal aperture, 6) structure of spines and 7) behaviour of egg-carrying. Therefore, an old generic name Tetramastix Zacharias, 1898 should be used again for this species. In addition, I agree with Wiszniewski (1954: 111) in the point that T. taiwanensis Harada, 1937 is synonymous with brevispina Ahlstrom, 1932, judging from figures by Harada (1937, Figs.1-4), although not a single specimen was collected this time from Taiwan. (ref. ID; 3083)
