Protozoologica. Mohamad Ahmad ALI INTRODUCTION. Acta Protozool. (2009) 48:

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1 Acta Protozoologica Acta Protozool. (2009) 48: Light and Scanning Electron Microscopy of Dipartiella simplex (Raabe, 1959) Stein, 1961 Infesting Common Sole (Solea vulgaris) and Goby Fish (Gobius sp.) in Lake Qarun, Egypt, with a New Character to the Genus Mohamad Ahmad ALI National Institute of Oceanography and Fisheries, Egypt Summary. Dipartiella simplex (Raabe, 1959) Stein, 1961 was observed on the gills of Solea vulgaris and Gobius sp. from Lake Qarun, Egypt. The trichodinid prevailed on the new host S. vulgaris all the year with high intensity during winter. Comparison with the original description revealed that the present trichodinid morphometry coincides with the minimal ranges of the original population and might be attributed to the new host and habitat. Scanning electron observations showed firm junctions of denticles through the fairly developed central parts. A new described character of this genus was clearly visible in the ray structure. Rays were semi-squared in form and ended with vermiform thin projections that were folded at right angles underneath the semi-square parts. The study provides a possible explanation for the present new locality and host in the saline inland lake of Qarun. Key words: Dipartiella, trichodinids, Solea, Gobius, protozoa, Lake Qarun, Egypt. INTRODUCTION Lake Qarun is an inland saline basin (29 24' and 29 33'N, 30 25' and 30 50'E) in the Fayoum Depression in the western desert of Egypt. It covers an area of about 228 km 2 (about 40 km in length and 5.7 km mean breadth). The lake ecosystem was transformed from freshwater to saline during the twentieth century. The new saline habitat of the lake made the ecosystem unfavourable for the freshwater forms. Hence, the authorities started to stock the lake with fry of marine forms like mullets and sole Address for correspondence: Mohamad Ahmad Ali, Ministry of Health-Public Health Dept. PO Box 42-Doha-Qatar; drmoh_ ali@yahoo.com since 1928 (El-Zarka 1963). These fry are annually collected from the coasts of the Mediterranean Sea. Saoud et al. (1990) surveyed the parasitic helminthes of fishes in Lake Qarun. Then, Ali (1996) studied the myxosporidia and trichodinids of the fishes of the Lake. Al-Bassel et al. (2007) described some trichodinids from Mugil cephalus in the Lake. Further to the parasitological investigation of fishes in Lake Qarun, the present work identified Dipartiella simplex (Raabe, 1959) Stein, 1961 on gills of Solea vulgaris and Gobius sp. The observed trichodinid was then redescribed using light and scanning electron microscopy (SEM) to check and validate denticle morphology. A new character was added to the genus in denticle structure. This study also provides comparative descrip-

2 266 M. A. Ali tions, as well as reviews the annual incidence of the parasite and comments on the geographical distribution and the new locality. MATERIALS AND METHODS Fish were collected on a monthly basis during a full year from fishermen at landing sites at the lake shores. A total of 165 S. vulgaris and nine Gobius specimens were examined. Gobius sp. was collected only in May and December as a non-commercial fish. Gills were kept in a Petri dish with tap water for 5 min. to reduce the salinity before smears were made. Positive slides were air dried and silver impregnated according to the modification of Klein s dry method (Lom 1958). All measurements are in micrometers and expressed as mean ± SD (range). In the case of the radial pins and denticle number, the mode is given instead of arithmetic mean. Body diameter was measured as the adhesive disc plus border membrane. Measurements followed those proposed by Lom (1958) while the method proposed by Van As and Basson (1989) was followed for denticle description. For SEM preparation, gills were preserved in 10% neutral buffered formalin, washed, dehydrated in ascending series of ethanol, critical point dried and sputter coated with gold. Specimens were examined in a Jeol Winsem JSM 6400 at 5 kv. RESULTS The infestation of gills of D. simplex on S. vulgaris was 77.6% (128/165) while it was 66.7 (6/9) among Gobius sp. The infestation in S. vulgaris was prevalent throughout the year with low to moderate intensity, except on December and January the intensity was high (Fig. 15). Gobius sp. was collected only in May and December and harboured moderate infestation levels. Denticle description Dipartiella observed from both fishes showed a very small and a relatively high spherical body. Adhesive discs usually had tightly packed denticles, but loose denticulate rings were also observed. Comparative measurements are shown in Table 1. Solea vulgaris: blade is variable, typical forms have wide triangular blades with round distal ends (Figs 1 5). Anterior blade surface is straight or slightly curved and does not extends to y + 1. Posterior blade surface slightly curved and almost equal to anterior blade surface. Central part is weakly developed but discernable with very small notch that is fitting in a protrusion of the preceding denticle. Adoral ciliary spiral was about 270 (Fig. 9). Macronucleus had two shapes; two round Table 1. Comparative morphometric characters of different records of Dipartiella simplex (Raabe, 1959) Stein, Denticle length (span) Nuclear apparatus Adoral spiral Rad.pins/ denticle Body diameter Adhesive disc Denticulate ring Denticle no. Raabe (10 22) 18 ( ) 8 ( ) 18 (17 20) 4 Horse shoe or 2 spherical structures 270 Kazubski ( ) 13.9 ( ) 6.3 ( ) 17.5 (14 21) ( ) Horse shoe or 2 elongate lobes 270 Xu et al (25 34) 26.3 (21 30) 11.0 (9 13) 25.1 (23 28) (4 6) C-shaped Present study: 12.0 ± 1.0 ( ) 9.5 ± 1.8 ( ) 6.0 ± 0.6 ( ) 19 (16 19) ± 0.3 ( ) 2 connected round lobes or bean shaped 270 Solea vulgaris (n = 40) 11.6 ± 1.3 ( ) 8.3 ± 0.2 ( ) 4.7 ± 0.3 ( ) 17 (16 18) ± 0.3 ( ) Gobius sp. (n = 25)

3 Morphology of Dipartiella simplex 267 Figs 1 9. Light micrographs of Dipartiella simplex (Raabe, 1959) Stein, silver impregnated adhesive discs; 1 5 from the gills of Solea vulgaris and 6 7 from Gobius sp.; 8 9 hematoxylin stained nuclear apparatus and 9 adoral ciliary spiral. Bar: 5 µm. lobes connected with a thin part and a kidney or bean shape. Micronucleus was not observed. Gobius sp.: blades are narrower and have sharp distal ends (Figs 6 7). Anterior blade surface straight and extends beyond y + 1. Posterior blade surface curved and shorter than anterior blade surface. Central part was not discerned. SEM observations The body of D. simplex appeared vaulted with a concave adhesive disc. The denticles are flat, ribbon like and noticeably compressed. Blades are wide and triangular forming about half of the denticle span. Central parts are not well defined and had prominent indentations that fit firmly into the preceding denticle (Figs

4 268 M. A. Ali 10 11). The central conical parts of the central parts are short and round. The rays are semi-square in form and ended with vermiform thin projections that were folded at right angles underneath the semi-square part (Figs 10, 12, 13). In some cases, these projections were unfolded and directed towards the center of the adhesive discs (Fig. 10). The ray parts were equal to or relatively longer than the blades. Radial pins are clearly separated. Some dividing forms were observed with the same pattern of normal division of trichodinids (Fig. 11). Figs Scanning electron microscopy of adhesive discs of Dipartiella simplex (Raabe, 1959) Stein, rudimentary rays (arrows); 11 a daughter cell after division with the mother denticulate ring being resorbed; 12 tight junction and clear interlocking of denticles through central parts (arrow); 13 rudimentary rays folded at right angles underneath the central parts (arrows). Bar: 1 µm.

5 Morphology of Dipartiella simplex 269 Fig. 14 a d. Diagrammatic drawings of the denticles of Dipartiella simplex (Raabe, 1959) Stein, a b from Solea vulgaris; c from Gobius sp.; d from electron scanned adhesive disc. (B) blade, (CP) central part, (R) ray. Fig. 15. Graphic representation of the monthly incidence of Dipartiella simplex (Raabe, 1959) Stein, 1961 on the gills of Solea vulgaris in Lake Qarun. DISCUSSION Dipartiella simplex was originally described by Raabe (1959) from Gobius niger in the Baltic sea. The description lacked photographic documentation and the trichodinid has not been found since then. Accordingly, Lom and Dykova (1992) regarded this species and the genus as possible mistaken identification of the genus Trichodinella. Therefore, Kazubski (1999) redescribed this trichodinid from the same slides of Raabe and described the species thoroughly. Meanwhile, Xu et al. (1999) described D. simplex from cultured fishes in China. However, the trichodinid did not match any of the mophometric characters of the D. simplex recorded by Raabe (1959), Kazubski (1999) or the present re-

6 270 M. A. Ali cord. The number of denticles was clearly out of the D. simplex range (23 28 vs ). Also, the adoral spiral was lower than the distinguished range of D. simplex ( vs. 270 ). In addition, all the morphometric data of the adhesive disc were almost double of the D. simplex in other records (see Table 1). Xu et al. (1999) did not provide justification for the presence of Dipartiella in this remote locality. The authors were seemingly not aware of the work of Kazubski (1999) published nearly at the same time and therefore did not have the suitable amount of data with which to compare. This means their description is more affiliated to Trichodinella lomi which they described from the same host as a new species, rather than D. simplex. The present population of D. simplex from S. vulgaris and Gobius sp. fall in the minimum range of the original description, which might be due to the both the new habitat or host. Other parameters such as number of denticles, nuclear apparatus, adoral ciliary and kin host (Gobius sp.) conform with Raabe s original description and that provided by Kazubski (1999). Scanning electron observations showed firm junctions of denticles through the fairly developed central parts. A newly described character of this genus was clearly visible as semi-square rays ended with vermiform thin projections which was not observed in the earlier studies. The present new host (S. vulgaris) and the new locality (Lake Qarun) might be explained as follows. Both infested hosts of the present study have geographical distributions that extend to the Baltic Sea (type locality) (Miller 1986 and Desoutter 1990). In addition, both species were originally translocated from the Mediterranean Sea and stocked in the Lake Qarun on more than one occasion during (El-Zarka 1963). It is worthy to mention that the prevalence of infestation on Solea fishes in Lake Qarun during the whole year suggests that this host is not accidental for D. simplex. This assumption could be confirmed by examining Solea fishes from both the Mediterranean and Baltic Seas. Acknowledgement. Thanks to Dr. Renee Richer, Weill Cornell Medical College in Qatar for her proof editing of the Ms. REFERENCES Al-Bassel D. A., Abdel-Baki A. S., Atwa M. S. (2007) Trichodinid ectoparasites (Ciliophora: Peritrichia) of Mugil cephalus Linnaeus, 1758 from Lake Qarun, Egypt. Egypt. J. Aquat. Biol. & Fish. 11(4): Ali M. A. (1996) Biological studies on trichodinids and myxosporeans infecting saline- and freshwater lakes in Egypt. Ph.D. Thesis, Fac. Sci., Cairo Univ., Egypt. El-Zarka S. (1963) Acclimatization of Solea vulgaris (Linn.) in Lake Qarun, Egypt. J. Cons. Perm. Int. Explor. Mer. 28: Desoutter M. (1990) Soleidae. In: Check-list of the fishes of the eastern tropical Atlantic (CLOFETA), (Eds. J. C. Quero, J. C. Hureau, C. Karrer, A. Post and L. Saldanha), Vol. 2. JNICT, Lisbon; SEI, Paris; and UNESCO, Paris, Kazubski S. L. (1999) Redescription of trichodinid Dipartiella simplex (Raabe, 1959) (Ciliophora: Peritrichida) and remarks on the genus Dipartiella Stein, Acta Protozool. 38: Lom J. (1958) A contribution to the systematic and morphology of endoparasitic trichodinids from amphibians, with a proposal of uniform characteristics. J. Protozool. 5: Lom J., Dykova I. (1992) Protozoan parasites of fishes. Elsevier, Amsterdam Miller P. J. (1986) Gobiidae. In: Fishes of the North-eastern Atlantic and the Mediterranean, (Eds. P. J. P. Whitehead, M.-L. Bauchot, J.-C. Hureau, J. Nielsen and E. Tortonese), Vol. 3. UNESCO, Paris, Raabe Z. (1959) Urceolaridae of gills of Gobiidae and Cottidae from Baltic Sea. Acta Parasit. Pol. 7: Saoud M. F. A., Ashour A. A., Ramadan M. M., Lamloom D. A. M. (1990) Helminth parasites of fishes from two inland lakes in Egypt. Jpn. J. Parasitol. 39: Van As J. G., Basson L. (1989) A further contribution to the taxonomy of Trichodinidae (Ciliophora: Peritrichida) and a review of the taxonomic status of some fish ectoparasitic trichodinids. Syst. Parasitol. 14: Xu K., Song W., Warren A. (1999) Trichodinid ectoparasites (Ciliphora: Peritrichida) from the gills of cultured marine fishes in China, with the description of Trichodina lomi n.sp. Syst. Parasitol. 42: Received on 23 rd November, 2008; revised version on 28 th April, 2009; accepted on 13 th May, 2009