Heterotachysoma dragescoi

Omar, Atef & Jung, Ji Hye Choi and Jae-Ho, 2023, New record of ten ciliate species (Protozoa, Ciliophora) from South Korea, Journal of Species Research 12 (1), pp. 95-108 : 96

2. Heterotachysoma dragescoi ( Song and Wilbert,

1997) Shao et al., 2013 ( Fig. 2 )

Material examined. Marine water (salinity 34.5‰) collected from Biin Bay , Seo-myeon, Seocheon-gun, Chungcheongnam-do, Korea (36°9 ʹ 5.30 ʺ N, 126°30 ʹ 47.40 ʺ E) on August 16, 2021 .

Diagnosis. Size in vivo 40 - 45 × 20 - 25 μm and 25 - 30 × 10 - 15 μm after protargol impregnation (n = 7);

body oval to elliptical; body flexible and slightly contractile; cortical granules colorless or slightly yellowish, about 1 μm in diameter, arranged in short, irregular lines of about 2 - 4 granules along dorsal kineties; 2 globular macronuclear nodules, each about 5 μm in diameter; 2 inconspicuous micronuclei each attached to macronucleus nodule; adoral zone of membranelles about one third of body length and composed of about 13 membranelles; right marginal row commences near mid-body and consists of 7 or 8 cirri, left marginal row consists of 7 or 8 cirri, marginal rows separate posteriorly; 3 frontal cirri, one buccal cirrus right to anterior portion of paroral membrane, 4 ventral, 3 postoral, 2 pretransverse, and 4 enlarged transverse cirri; three dorsal kineties with relatively widely spaced dikinetids; caudal cirri lacking.

Distribution. China, South Korea.

Remarks. The Korean population of Heterotachysoma dragescoi is identical to the type population described by Song and Wilbert (1997). Shao et al. (2013) established the genus Heterotachysoma and included oxytrichid ciliates without caudal cirri, dorsomarginal kineties, nor kinety fragmentation. To date, the genus Heterotachysoma contains three species, H. multinucleatum ( Gong and Choi, 2007) Shao et al., 2013 , H. dragescoi , and H. ovata ( Song and Wilbert, 1997) Shao et al., 2013 (type species). The three species differ mainly in the nuclear apparatus (2 macronuclear nodules and 2 micronuclei in H. dragescoi , 2 macronuclear nodules and one macronucleus in-between in H. ovata , and several macronuclear nodules in H. multinucleatum ) ( Song and Wilbert, 1997; Gong and Choi, 2007; Shao et al., 2013).

Voucher slides. One slide with protargol-impregnated specimens was deposited at the National Institute of Biological Resources, Korea (NIBRPR0000111067).

Figures

Fig. 2. Heterotachysoma dragescoi in life (A-C) and after protargol impregnation(D). A-C, Dorsal (A, B) and ventrolateral(C) view showing the shape and flexibility of body and the shape and arrangement of cortical granules(arrows). D, Ventral view showing the infraciliature and the nuclear apparatus. AZM, adoral zone of membranelles; BC, buccal cirrus; FC, frontal cirri; LM, left marginal row; MA, macronuclear nodule; RM, right marginal row; TC, transverse cirri. Scale bars 20 μm (A-C) and 10 μm (D).