Diophrys japonica Hu, 2008

Choi, Ji Hye & Jung, Atef Omar and Jae-Ho, 2025, New record of four spirotrichs (Protozoa, Ciliophora) from South Korea, Journal of Species Research 14 (1), pp. 38-47 : 44-45

4. Diophrys japonica Hu, 2008 ( Fig. 5 )

Material examined. Marine water (salinity unknown, temperature 17.0℃) collected from Gangdong-myeon , Gangneung-si, Gangwon-do, South Korea (37°45 ʹ 48 ʺ N, 128°57 ʹ 53 ʺ E) on August 24, 2022 .

Diagnosis. Size 47-76 × 35-53 μm after protargol impregnation (n = 11); body broadly elliptical with distinct concavity at right posterior portion ( Fig. 5A ); adoral zone, composed of 36-43 membranelles, occupies about 70% of body length in staining specimens ( Fig. 5A ); five frontal, two ventral, and five transverse cirri; always one left marginal and three caudal cirri ( Fig. 5A ); four continuous dorsal kineties ( Fig. 5B ); two ovoidal to ellipsoidal macronuclear nodules, 11-15 × 8-11 μm each after protargol impregnation ( Fig. 5A, B ); 2-5 globular micronuclei, 1.3- 2.2 μm in diameter, attached to the macronuclear nodules ( Fig. 5A ).

Distribution. Japan (type locality, Hu, 2008), Korea (in this study).

Remarks. The Korean population of Diophrys japonica corresponds to the Japanese population in all aspects except for the body length (47-76 μm vs. 91-142 μm after protargol impregnation) ( Hu, 2008, population I). Hu (2008) provided the morphometric data based on three populations (i.e., populations I, II, IV) and the populations II and IV shows similar body length to the Korean one (60-82 μm, 58-112 μm). Among the twelve species belonging to the genus Diophrys , excluding the poorly-known species D. salina Ruinen, 1938 and D. peloetes Borror, 1965 , five species have sausage-shaped macronucleus nodules ( D. apoligothrix Song et al., 2009 ; D. appendiculata ; D. parappendiculata Shen et al., 2011 ; D. oligothrix ; and D. scutum ), while five species have ovoidal to ellipsoidal macronucleus nodules ( D. blakeneyensis Hu et al., 2012 ; D. japonica ; D. pauciciliata ; D. peculiaris Luo et al., 2014 ; and D. quadrinucleata ) ( Zhang et al., 2020; Choi et al., 2022). Considering the shape of the macronucleus nodules, D. japonica should be compared with the latter five species. Diophrys japonica can be easily distinguished from D. blakeneyensis and D. quadrinucleata by the number of macronucleus nodules (2 vs. 7-23 in D. blakeneyensis and 4 in D. quadrinucleata ) ( Hu et al., 2012; Zhang et al., 2020). Additionally, D. blakeneyensis differs from D. japonica by the number of frontal cirri (7 vs. 5) and dorsal kineties (5 vs. 4) ( Hu et al., 2012). Diophrys pauciciliata and D. peculiaris are also similar to D. japonica . However, D. pauciciliata differs from D. japonica by having a bipartite adoral zone of membranelles (vs. continuous) and five fragmented dorsal kineties (vs. four continuous dorsal kineties) ( Choi et al., 2022). Also, D. peculiaris differs from D. japonica by the number of left marginal cirri (2 vs. 1) ( Luo et al., 2014).

Voucher slides. Two slides with protargol-impregnated specimens were deposited at the National Institute of Biological Resources (NIBRPR111183, NIBRPR111184).

Figures

Fig. 5. Diophrys japonica after protargol impregnation (A, B). A. Ventral view showing the body shape, adoral zone of membranelles, frontal, ventral, transverse, caudal and leftmarginal cirri, and nuclear apparatus.Arrowheads denote micronuclei. B. Dorsal view showing dorsal kineties. AZM, adoral zone of membranelles; CC, caudal cirri; DK, dorsal kineties; FC, frontal cirri; LMC, left marginal cirrus; MA, macronuclear nodules; TC, transverse cirri; VC, ventral cirri. Scale bar: 20 μm.