Ceratomyxa triacantha, Zhao & Al-Farraj & Al-Rasheid & Song, 2015

Zhao, Yuanjun, Al-Farraj, Saleh A., Al-Rasheid, Khaled A. S. & Song, Weibo, 2015, Data on Ten New Myxosporean Parasites (Myxozoa, Myxosporea, Bivalvulida) from the Yellow Sea, China, Acta Protozoologica 54 (4), pp. 305-323 : 320-322

Ceratomyxa triacantha sp. n. ( Fig. 4M–T ; Table 2)

This organism was incorrectly marked as Ceratomyxa triacanthi Zhao and Song, 2003 in the monograph “Pathogenic Protozoa in Mariculture” ( Song et al. 2003), which has not been described as a new species in that book. Thus, according to ICZN, the species should be an invalid name, hence, we “re-establish” and “re-describe” this form here.

Diagnosis: Irregular disporous trophozoites with several filiated pseudopods and granulated cytoplasm; mature spore symmetric arciform with conical shell-valves, ends of valves rounded with a smooth surface, evident sutural line from a sutural view, 14.5 ± 1.8 (13.0–16.5) in thickness, 6.6 ± 0.6 (6.0–7.0) in length, posterior angle deeply concave (88–122°); two smaller spherical polar capsules positioned in a plane perpendicular to the sutural line, 2.1 ± 0.1 (2.0–2.5) µm in diameter; fine sporoplasm with one binuclear located in the spore cavity; coelozoic.

Type host and site of infection: Gall bladder and bile of Triacanthus brevirostris Temminck and Schlegel, 1846 .

Type locality: Coastal waters of the Yellow Sea off Qingdao, China (36°08′N, 120°43′E). Salinity about 32‰, water temperature about 14°C .

Prevalence: Only one fish was obtained and infect- ed (100%).

Date of sampling: June 11, 1998.

Host symptom: Unknown.

Type material: The holotype, on an air-dried slide stained with Giemsa (Coll. No. qd-19980611a), and a paratype slide stained with Giemsa (Coll. No. qd- 19980611b) were deposited at the Collection Center of type-specimens, Chongqing KLAB, Chongqing Normal University , China .

Etymology: The species name recalls the host from which this species was originally isolated.

Description: Early stage plasmodia were irregular in general form, and locomoted typically with an amoe- ba-like movement. When these plasmodia with granulated cytoplasm moved they temporarily extended several long filament pseudopods at the anterior end ( Fig. 4O, Q ), which were (53.0 × 23.5) in size; later the plasmodia shortened with several pseudopods when spores were developing in it; becoming 26.5 ± 8.7 (17.5–35.5) × 15.3 ± 2.7 (13.0–19.0) in size. The interior of the trophozoite was occupied by two spores ( Fig. 4M–N, P ). Mature spores were arciform with rounded ends which were symmetrical from a sutural view; sutural line was straight, and each theca with a theca nuclear at the end was smooth and tipped more or less in the end. Posterior angle is deeply concave (88–122°). Two spherical polar capsules were equal in size and positioned anteriorly in the spore cavity in a plane perpendicular to the sutural line ( Fig. 4R–T ). No transparent mucus surrounded the spore. Measurements of spores are given in Table 2 (n = 20).

Comparison and comments: The new species is similar to C. gobioidesi Chakravarty, 1939 and C. etroplusi Rajendran and Janardanan, 1992 . It differs from the latter, however, in having a longer spore length (6.0–7.0 vs. 4.0–5.0 in C. gobioidesi ), and slightly smaller diameter of polar capsule (2.0–2.3 vs. 2.5–3.0 in C. gobioidesi ); different forms of trophozoites (irregular with filament pseudopod vs. round or dish-form in C. gobioidesi ) and in size (17.5–53.0 × 13.0– 23.5 in the former vs. 500.0–600.0 in diameter in C. gobioidesi ). Whereas the present organism differs from C. etroplusi in that: 1) the polar capsules differ from each other in shape (spherical in the former vs. furiform in the latter); 2) length of spore larger in the former than in the latter (6.0–7.0 vs. 4.5–6.0); 3) different shape of spore (symmetric arch vs. asymmetric crescent).

Figures

Fig. 4. Schematic illustrations of Ceratomyxa spp. A–G – Ceratomyxa saurida sp. n.; A–D, G – lateral view of mature spore; E – lateral view of abnormal spore; F – lateral view of immature spore; H–L – Ceratomyxa simplex sp. n.; H, J – lateral view of mature spore; I – immature spore viewed from the perspective of the capsule; K–L – plasmodia with one spore; M–T – Ceratomyxa triacantha sp. n.; M–N, P – plasmodia with two spores; O, Q – early stage plasmodia with many nuclei; R–T – sutural view of mature spores. Scale bars: 10 µm.