Volume 51, Issue 3

A species of Sarcocystis is reported from a naturally infected African grey parrot, Psittacus erithacus, from Costa Rica. Only mature sarcocysts, measuring up to 2 mm in length and up to 750 μm in width, were observed. The sarcocyst wall was smooth. The villar protrusions on the sarcocyst wall were up to 5 μm long and up to 1.1 μm wide; they were folded over the sarcocyst wall giving a thin-walled appearance. The microtubules in villar protrusions were smooth and confined to villar protrusions. Bradyzoites in sections were 5.4–6.6 × 1.3–2.0 μm in size. Sequencing the small subunit and first internal transcribed spacer portions of ribosomal DNA related this parasite to, but distinguished it from, previously characterized species of Sarcocystis that encyst in the musculature of birds and complete their sexual development in New World opossums of the genus Didelphis. This evidence suggests that the parrot may have acquired its infection from an opossum from which it suffered a debilitating attack a year prior to the onset of depression, anorexia, and ultimately death.

Fifteen species of digeneans are reported from the waters off the islands of the Outer Hebrides, off north-western Scotland. Trifoliovarium allocytti comb. nov. from Neocyttus helgae is described, figured, and reported for the first time in the northern hemisphere. Brachyenteron helicoleni sp. nov. from Helicolenus dactylopterus is described and considered distinct from other species in the genital pore being at the level of the pharynx, the relatively narrow caeca, the vitellarium being mainly at the level of the ventral sucker and the anterior hindbody, the posteriorly situated, oblique testes, the small amount of post-testicular uterus, the small, delicate cirrus-sac and the large eggs. Derogenes varicus and Lepidapedon arlenae are reported from Caelorhinchus labiatus and Paralepidapedon williamsi is reported from Cottunculus thomsoni for the first time. Steringovermes notacanthi and Prodistomum priedei are reported from off Scotland for the first time. The reports of Derogenes varicus at 1,800 m depth and Zoogonoides viviparus at 1,000 m are deeper records than have previously been published.

Specimens of the fishes Lethrinus nebulosus Forsskål (Lethrinidae) and Diplodus noct Valenciennes (Sparidae) were caught in the Red Sea off the coast of Sharm El-Sheikh, South Sinai, Egypt. Ten (33%) and 12 (24%) of these fishes, respectively, were found to harbour intestinal trematodes. L. nebulosus was parasitised by Pachycreadium lethrini sp. nov. (Opecoelidae) and D. noct by Pseudometadena aegyptensis sp. nov. (Cryptogonimidae). P. lethrini sp. nov. is unique in having distinctly unequal testes, contiguous gonads arranged obliquely in the right side of hindbody and a small egg size. However, it differs from each of the other three species of the genus in several other features: from P. gastrocotylum (Manter, 1940) Manter, 1954 in having a smaller sucker ratio and vitelline follicles terminating anteriorly at the level of intestinal bifurcation; from P. carnosum (Rudolphi, 1819) Cortini et Ferretti, 1959 in having a smaller body, a smaller sucker ratio, a genital pore situated ventrally to the anterior border of pharynx, a pretesticular ovary and vitelline follicles extending anteriorly to the level of intestinal bifurcation; and from P. lerneri Sogandares-Bernal, 1959 in having a larger body, a smaller sucker ratio and an unlobed ovary. P. angolensis Aleshkina et Gaevskaya, 1985 is considered an invalid species in Pachycreadium. P. aegyptensis sp. nov. is similar to P. celebesensis Yamaguti, 1952, but mainly differs in having a larger pharynx, a much shorter oesophagus, extensive vitelline acini and a shorter seminal vesicle. Pachycreadium Manter, 1954 and Pseudometadena Yamaguti, 1952 are briefly reviewed.

The first description of vitellogenesis in the Trypanorhyncha is presented in this paper. Though the type of vitellogenesis and mature vitellocyte in Dollfusiella spinulifera appear to be unique among the Eucestoda, to some extent they resemble that observed in the lower cestodes, namely the Tetraphyllidea and Pseudophyllidea. Maturation is characterized by: (1) an increase in cell volume; (2) extensive development of large, parallel, frequently concentric cisternae of GER that produce proteinaceous granules; (3) development of Golgi complexes engaged in packaging this material; (4) continuous enlargement of proteinaceous granules within vesicles and their transformation into shell globule clusters; and (5) progressive fusion of all vesicles, with flocculent material containing the proteinaceous granules and shell globule clusters, into a single very large vesicle that characterises mature vitellocytes of this tapeworm. Cell inclusions in and around the large vesicle consist of flocculent material of a very low density, a few shell globule clusters, moderately dense proteinaceous granules and numerous large droplets of unsaturated lipids. A new previously unreported mode of transformation of proteinaceous granules into shell globule clusters, that evidently differs from that of pseudophyllideans and tetraphyllideans, is described. Cytochemical staining with periodic acid-thiosemicarbazide-silver proteinate for polysaccharides indicates a strongly positive reaction for membrane-bound glycoproteins in all membranous structures such as GER, mitochondria, Golgi complexes, nuclear and cell plasma membranes. Similar staining revealed β-glycogen particles scattered in the cytoplasm of maturing vitellocytes. Typical cytoplasmic β-glycogen particles appear mainly during early vitellocyte maturation but it is characteristic for this species that they are only seldom visible in mature cells. Some working hypotheses concerning the interrelationship between this particular pattern of vitellogensis, possible mode of egg formation in D. spinulifera, its embryonic development and trypanorhynchean life cycle, are drawn and discussed.

The present study describes the ultrastructure of mature vitellocytes of the trypanorhynch cestode Progrillotia pastinacae Dollfus, 1946 (Progrillotiidae), a parasite of the common stingray Dasyatis pastinaca (Linnaeus, 1758) (Dasyatidae). The vitelline cells of this species measure about 24 μm in length and about 20 μm in width. They have small, elongated, slightly lobulated nuclei, about 4–5 μm in length, with large dense elongated nucleoli and numerous irregularly-shaped dense clumps of heterochromatin. The extensive cytoplasm is rich in numerous cell organelles and cell inclusions. While the perinuclear cytoplasm contains numerous long parallel cisternae of GER, ribo-and polyribosomes, several Golgi complexes and mitochondria, the peripheral cytoplasm contains predominantly three types of cell inclusions: a great number of large lipid droplets, several shell globule clusters, and a very small amount of glycogen-like particles. The most characteristic features of vitellocytes in P. pastinacae are having almost no traces of glycogen and the great number of large, highly osmiophobic lipid droplets representing saturated fatty acids. The presence of large amounts of lipids also in two other trypanorhynchs, Grillotia erinaceus (Beneden, 1858) Guiart, 1927 and Dollfusiella spinulifera (Beveridge et Jones, 2000) Beveridge, Neifar et Euzet, 2004, is in strong contrast to the condition in the most evolved cestodes, Cyclophyllidea, that usually show no trace of lipids.

The ultrastructure of the mature spermatozoon and the spermiogenesis of a cestode belonging to the family Metadilepididae is described for the first time. The mature spermatozoon of Skrjabinoporus merops is characterized by twisted peripheral microtubules, the presence of a single crested body, periaxonemal sheath and electron-dense rods, and the absence of intracytoplasmic walls and inclusions (glycogen or proteinaceous granules); no peripheral microtubules where nucleus contacts the external plasma membrane. Four morphologically distinct regions of the mature spermatozoon are differentiated. The proximal part (Region I) contains a single crested body, periaxonemal sheath is absent in some (proximal) sections and is present in others situated closer to the nucleus. The central Region II is nucleated, and is followed by Region III that contains a periaxonemal sheath. The distal pole, Region IV, is characterized by disintegration of the axoneme. Spermiogenesis follows the type III pattern (Bâ and Marchand 1995) although in S. merops a slight flagellar rotation is observed. The differentiation zone is characterized by the absence of striated roots and intercentriolar body; two centrioles are present, one of which gives rise to a free flagellum. The latter rotates and undergoes proximodistal fusion with the cytoplasmic protrusion of the differentiation zone. Spermiological characters of S. merops are similar to those of the families Taeniidae and Catenotaeniidae. The mature spermatozoon differs from those of the Dilepididae (where the metadilepidid species have previously been classified) by the lack of glycogen.

We studied the parasitization by Anisakis spp. in European hake (Merluccius merluccius) of 40–52 cm from the Atlantic off north-west Africa and the Mediterranean off southern Spain. Infection parameters differed: The fish from the Atlantic showing a prevalence of 87.97% and a mean intensity of 4.69, while, in those from the Mediterranean, these were 41.27% and 1.73, respectively. In both samples the two-third larval stage types were isolated: Anisakis simplex sensu lato and Anisakis larvae type II, with prevalence of 85.71% and 30.83% in fish from the Atlantic and 41.27% and 1.59% for those from the Mediterranean, respectively. In both samples, the prevalence of larvae in viscera was clearly higher than in the muscle tissue. We also observed an increase in parasitization with increasing host length, those ≥ 46 cm having the highest prevalences (94.87% for those from the Atlantic and 58.33% for those from the Mediterranean; p<0.03).

Cosmocerca tyleri sp. nov. (Ascaridida, Cosmocercidae) from the large intestine of Genyophryne thomsoni (Anura, Microhylidae) is described and illustrated. Cosmocerca tyleri sp. nov. represents the 23rd species assigned to the genus and the 6th from the Australian realm. Of the 5 Australian species previously described, C. tyleri sp. nov. differs from C. limnodynastes and C. novaeguineae in number of plectanes, 4 pairs in C. tyleri, 5 pairs in C. limnodynastes and C. novaeguineae. Cosmocerca australis has 3–4 pairs of plectanes, C. archeyi and C. zugi each have 4 pairs of plectanes; however, in each species the plectanes lie in the fourth quarter of the body and just anterior to the cloaca. In C. tyleri sp. nov. the plectanes lie in the third quarter of the body and there is significant space between the cloaca and the posterior pair of plectanes.

Paragordius is a genus of Gordiida with a worldwide distribution, but with a scarce specific diversity. Sixteen species of the genus Paragordius have been described so far. In many cases, as with the other genera of Gordiida, the original descriptions of the species are insufficient due to the limitations of the techniques employed. In this work the holotypes of P. minusculus and P. esavianus are redescribed by scanning electron microscopy (SEM), a new species of Paragordius is described, the distribution for P. esavianus and P. varius is enlarged and a new host record of P. esavianus is presented.

Cymothoa indica, a typical Indo-Pacific genus and species, is reported for the first time in the eastern Mediterranean Sea. Specimens were found parasitizing mainly barracudas (Sphyraenidae) from Lebanon. Female and male specimens are described on collected materials. To date, the genus Cymothoa has not been reported in the Mediterranean Sea although it is widely represented in other areas of the world. It is suggested that C. indica should be added to the list of exotic species introduced from the Red Sea and known as Lessepsian migrants.