Parastrombidinopsis pelagica ( Fauré-Fremiet, 1924 ) Song & Li & Huang & Al-Rasheid & Liu & Hu & Miao, 2018

Song, Wen, Li, Jiamei, Huang, Yaoyao, Al-Rasheid, Khaled A. S., Liu, Weiwei, Hu, Xiaozhong & Miao, Miao, 2018, Morphology of Three Aloricate Choreotrich ciliates, Including Description of a New Species Parastrombidinopsis costalis sp. n. (Ciliophora, Choreotrichia), and phylogeny of the genus Parastrombidinopsis, Acta Protozoologica 57 (3), pp. 153-167 : 164

Parastrombidinopsis pelagica ( Fauré-Fremiet, 1924) comb. n. and comparison with related species ( Table 3)

This species was first reported as Strobilidium pelagicum by Fauré-Fremiet (1924) with a brief description of the organism in vivo. Jankowski (2007) transferred the species to the genus Strombidinopsis Kent, 1881 based only on the original description. The Zhanjiang population corresponds well with the original description regarding the cell size, cell shape, macronucleus, oral membranelles, somatic kineties and habitat, thus, we think our population can be conspecific to Strobilidium pelagicum Fauré-Fremiet, 1924 . Given the ventral gap of collar membranelle bases revealed by protargol staining, however, we think this species should be transferred to the genus Parastrombidinopsis Kim et al., 2005 as P. pelagica ( Fauré-Fremiet, 1924) comb. n.

Parastrombidinopsis pelagica ( Fauré-Fremiet, 1924) comb. n. most resembles P. shimi in its cell size and number of collar membranelles, but can be easily separated from the latter by having fewer somatic kineties (13–15 vs. 36–50). Parastrombidinopsis pelagica ( Fauré-Fremiet, 1924) comb. n. differs from P. costalis sp. n. by having: 1) a larger cell size (100–170 × 40– 60 μm vs. 60–70 × 25–40 μm in vivo); 2) more collar membranelles (31–36 vs. 19–21); and 3) more somatic kineties (13–15 vs. 6–8). In addition, Parastrombidinopsis pelagica ( Fauré-Fremiet, 1924) comb. n. can be separated from P. minima by: 1) the arrangement of the AZM (the proximal end located below the distal end vs. distributed on same horizontal level); 2) the larger cell size (100–170 × 40–60 μm vs. 60–95 × 30–70 μm in vivo); 3) and the presence of more collar membranelles (31–36 vs. 12–18).