Sphaerospora sebast

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 : 306-309

Sphaerospora sebast a sp. n. ( Figs 1A–E , 5A–B ; Table 1)

This organism was incorrectly marked as Sphaerospora sebastis 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: Mature spore spherical with a smooth surface, fine sutural line, 15.3 ± 0.4 (14.7–15.7) in length, 15.7 ± 1.0 (14.7–16.7) in width, 15.0 ± 0.4 (14.7–15.3) in thickness; two smaller spherical polar capsules positioned anteriorly in a plane perpendicular to the sutural line, 2.9 ± 0.2 (2.7–3.0) in diameter; fine sporoplasm with one binuclear posteriorly in spore cavity; coelozoic.

Host and site of infection: Gall bladder of Sebastes schlegeli Hilgendorf, 1880 .

Type locality: Coastal cultural waters off Jiaonan (35°48N, 119°54′E), Yellow Sea , China. Salinity about 31‰, water temperature about 15°C

Prevalence: Of the three fish examined, two were infected (67%).

Date of sampling: June 2, 1999.

Host symptom: The bile color of the infected gall bladder changed into yellowish and the cultured fish, Sebastes schlegeli died possibly due to myxosporean infection combined with monogeneans. Meanwhile, another three species of monogeneans lived in the gill filaments of the same host.

Type material: The holotype, on an air-dried slide stained with Giemsa (Coll.: No. jn-199900602a), and a paratype slide stained with Giemsa (Coll.: No. jn- 199900602b), 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: A vegetative stage was not observed. The mature spore was spherical and smooth with a straight sutural line; there were two smaller polar capsules, spherical, about equal in size and located anteriorly in a plane perpendicular to the sutural line. Sporoplasm with two mononuclears positioned posteriorly in the spore cavity ( Figs 1A–E , 5A–B ). An iodinophilous vacuole was not evident in the sporoplasm nor a mucous envelope around the spore. Measurements of spores are given in Table 1 (n = 25).

Comparison and comments: To date, over 50 species of Sphaerospora have been isolated from marine and freshwater fish, with most of these being coelozoic and parasitizing in the urinary bladder or renal tubules and ureters and so on, occasionally in the gall bladder ( Arthur and Lom 1985, Supamattaya et al. 1991, Sitja-Bobadilla and Alvarez-Pellltero 1994, Chen and Ma 1998), 17 of these 50 species were from marine or brackish waters. Considering the site of infection, the new species is different from many Sphaerospora species in that our organism parasitized in the gall bladder of marine fish, and also in its spherical mature spore with a smooth surface, fine sutural line; two smaller spherical polar capsules positioned anteriorly in a plane perpendicular to the sutural line, fine sporoplasm with one binuclear posteriorly in the spore cavity. The comprehensive spore-body characters of the current organism is different to any other known-species of the genus Sphaerospora . The current species, therefore, is considered a new species.

Family Ceratomyxidae Doflein, 1899

Genus Ceratomyxa Thélohan, 1892

Figures

Fig. 1. Schematic illustrations of three myxosporean species. A–E – Sphaerospora sebasta sp. n.; A – mature spore from a frontal view; B–C – spore viewed from the perspective of the capsule; D – spore from a sutural view; E – spore from an oblique sutural view; F–H – Ceratomyxa sebastisca sp. n., showing mature spores with coarse sporoplasm; I–O – Ceratomyxa hemitriptera sp. n.; I–J – mature spore from a lateral view; K–L – plasmodium with one mature spore; M–N – early stage plasmodium with one developing spore; O – plasmodium with one developing spore from a capsule view. 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.