Ceratomyxa lomi, 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 : 316-317

Ceratomyxa lomi sp. n. ( Figs 3A–E , 5I–J ; Table 2)

This organism was incorrectly marked as Ceratomyxa lomi 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: Trophozoites disporous; elongat- ed forked to strongly arcuate mature spores with shell-valves often conical, exceeding in length the axial diameter of the spore; ends of valves tipped with a smooth surface; sutural line fine, 58.0 ± 8.1 (49.0– 69.0) in thickness, 5.2 ± 0.9 (4.0–6.0) in length, posterior angle extremely concave (115–135°); two smaller spherical polar capsules positioned anteriorly in a plane perpendicular to the sutural line, 2.7 ± 0.2 (2.5–3.0) in diameter, polar filament 40.0–48.0 in length; fine sporoplasm with one binuclear in spore cavity; coelozoic.

Type host and site of infection: Gall bladder of Lateolabrax japonicus (Cuvier and Valenciennes 1828) .

Type locality: Rongcheng (37°18′N, 12242′E) natural water and coastal aquaculture waters off Jiaonan (35°48′N, 119°54′E) of the Yellow Sea, China. Salinity about 31–32‰, water temperature about 12–15°C .

Prevalence: Of the one fish examined from Rongcheng, one was infected (100%); of the four fish examined from Jiaonan, two were infected (50%).

Date of sampling: April 26, 1999 and June 2, 1999.

Host symptom: Many plasmodia and spores massed and floated in gall bladder, and epithelial cells of blad- der wall exfoliated.

Type material: The holotype, on an air-dried slide stained with Giemsa (Coll.: No. rc-19990426), and a paratype slide stained with Giemsa (Coll.: No. jn- 19990602), were deposited at the Collection Center of type-specimens, Chongqing KLAB, Chongqing Normal University , China .

Etymology: We dedicate this new species to our distinguished colleague, Dr Jirí Lom, Institute of Parasitology, Academy of Sciences of the Czech Repub- lic, in recognition of his academic contributions to myxosporology.

Description: Early stage plasmodia were not seen. Later stages exhibited a peripheral layer of hyaline non-granular ectoplasm containing two developing spores non-mirror arranged, arcuate in shape and 50 × 14 µm in size; trophozoites disporous ( Fig. 3E ). Spores typical of the genus Ceratomyxa . Elongated forked to strongly arcuate mature spores with shell-valves often conical, exceeding in length the axial diameter of the spore; ends of valves tipped with a smooth surface, sutural line fine, nearly straight from capsular view ( Fig. 3A ); anterior margin extremely convex and posterior margin strongly concave from a sutural view ( Fig. 3B–D ); the two valves were smooth and equal with two strongly tapering ends. Posterior angle extremely concave (115– 135°). Two equal furiform polar capsules positioned anteriorly in a plane perpendicular to the sutural line; one binuclear sporoplasm which is often finely granulated located in the spore cavity; without iodinophilous vacuole. No mucous envelope evident around the spore. Measurements of spores are given in Table 2 (n = 20).

Comparison and comments: Considering the shape and size of the spore, the new species is similar to C. daysciaenae , isolated from a bayou of the Hooghly River in West Bengal, India ( Sarkar and Pramanik, 1994), but the new species is different from C. daysciaenae in having a forked-form spore-body shape with two conical theca (vs. ellipse-form spore-body central with two conical theca for C. daysciaenae ). The new form is also similar to C. sagarica ( Choudhury and Nandi, 1973) , however, the spores of the new species without any iodinophilous vacuole in sporoplasm are more large than ones of the latter with iodinophilous vacuole in sporoplasm (49.0–69.0 × 4.0–6.0 vs. 26.5–36.3 × 3.3–4.1). Although the current species is superficially similar to C. furcata Fujita, 1923 in its spore-body, but the differences between the two species are as follows: 1) different length of spore (4.0–6.0 vs. 11.0–13.0); 2) different hosts ( Lateolabrax japonicus vs. Limanda herzensteini ). Up to date, only Ceratomyxa acuta Schulman, 1966 has been reported from the gall bladder of Lateolabrax japonicus . The current species differs from C. acuta in having a different spore-body shape (forked-form for the new species vs. straight form for the latter) and dimensions (49.0–69.0 × 4.0–6.0 for the species vs. 39.0–52.0 × 5.0–6.0 for C. acuta ) ( Table 2).

Figures

Fig. 3. Schematic illustrations of Ceratomyxa spp. A–E – Ceratomyxa lomi sp. n.; A – mature spore viewed from the perspective of the cap- sule; B–D – lateral view of mature spore; E – plasmodium with two mature spores; F–J – Ceratomyxa lateolabrax sp. n.; F – plasmodium with two spores; G–J – lateral view of mature spore; K–N – Ceratomyxa qingdaoensis sp. n.; K–L, N – showing a lateral view of a mature spore; M – lateral view of an immature spore. Scale bars: 10 µm.

Fig. 5. Microphotographs of myxosporean species. A–B – Sphaerospora sebasta sp. n.; C – Ceratomyxa sebastisca sp. n.; D–E – Ceratomyxa hemitriptera sp. n.; F–H – Ceratomyxa kareus sp. n.; I–J – Ceratomyxa lomi sp. n. Scale bars: 10 µm.