Mem Inst Oswaldo Cruz, Rio de Janeiro, 91(6) Nov/Dez 1996
Spasskyellina mandi n. sp. (Proteocephalidea: Monticelliidae), Parasite of Pimelodus ornatus Kner, 1857 (Pisces: Pimelodidae) of the Paraná River, Paraná, Brazil
Núcleo de Pesquisas em Limnologia, Ictiologia e Aqüicultura (NUPELIA), Universidade Estadual de Maringá, Av. Colombo 5790, 87020-900 Maringá, PR, Brasil
Spasskyellina mandiu00a0n. sp. (Proteocephalidea: Monticelliidae) is described from the Siluriform fishu00a0Pimelodus ornatus Kner, 1857, caught in the Paraná River, Paraná, Brazil. The new species differs from other species of the same genus mainly by a fewer number of testes and by a larger osmoregulatory canal. This is the second species of proteocephalidean cestode collected inu00a0P. ornatus.
As a continuation to their study on parasites of fishes of the Paraná River, Porto Rico region, PR, Brazil, the authors describe a new species of proteocephalidean cestode, Spasskyellina mandi n. sp. collected in Pimelodus ornatus Kner, 1857. According to Nomura (1984) the fish is a Siluriform fish found in the rivers Parnaíba, Negro and high Paraná, and in Mato Grosso, Goiás, Paraguay, Guianas, Bolivia, Peru and Venezuela. Recently Chambrier and Rego (1995) have made a description of Mariauxiella pimelodi which constitutes the first reference of a proteocephalid in the same species of fish.
MATERIALS AND METHODS
Twenty-eight specimens of P. ornatus were examined between March 1992 and February 1995. The fishes were caught in the Paraná River, near Porto Rico, PR. Immediately after capture, the fishes were identified and eviscerated, and the intestines were isolated and examined in Petri dishes containing a 0.65% physiological saline solution using a stereomicroscope. The isolated helminths were placed in distilled water to relax before the occurrence of death, in refrigerator or they were fixed in hot 10% formalin. Specimens for study in toto were stained with Delafield's haematoxylin or Langeron's alcoholic chloridric carmine, cleared in beechwood creosote and mounted in Canada balsam. Pieces of strobila were embedded in paraffin wax, sectioned at 5mm and stained with haematoxylin eosin. The illustrations were prepared with a drawing tube and a NIKON YS 2 microscope. Measurements are in millimeters unless otherwise indicated, with ranges followed by mean within parentheses. The holotype and some paratypes were deposited in the Instituto Oswaldo Cruz Collection (CHIOC), Rio de Janeiro, RJ, Brazil. Prevalence, intensity of infection and mean intensity of infection are used according to Margolis et al. (1982).
Spasskyellina Freze, 1965 emend.
Scolex globose. No metascolex. Suckers armed with several rows of minute spines. Ovary, testes and uterus entirely cortical. Uterine slit formed early. Uterine diverticula slightly or well developed. Longitudinal musculature slightly developed. Vagina always posterior to cirrus sac. In South American fishes.
Description - (Based on nine specimens, all measured). Medium size helminths. Acraspedote strobila, 2.09 - 60.39 (17.69) in length, bearing about 65 proglottides. Neck 0.42 - 0.75 (0.62) long. Mature proglottides slightly longer than wide 0.14 x 0.19 - 0.80 x 0.70 (0.40 x 0.38); gravid proglottides longer than wide 0.32 x 0.26 - 1.79 x 0.63 (0.95 x 0.47). Small scolex, slightly differentiated from strobila 0.12 x 0.13 - 0.22 x 0.26 (0.16 x 0.21) with four antero-lateral suckers, 0.05 - 0.10 (0.08) in diameter, surrounded by small spines. Apical organ lacking. Metascolex absent. Internal longitudinal musculature inconspicuous. Ventral osmoregulatory canal broad, 0.025-0.082 (0.050) in diameter. Twenty-five to fifty-one (36) oval testes in only one cortical and dorsal field, extending to vitellaria with 6-13 (10) preporal, 5-9 (7) postporal and 14-30 (19) antiporal, with 0.02-0.05 (0.04) in diameter. Cirrus pouch claviform slender-walled, 0.13-0 .22 (0.18) long and 0.04-0.09 (0.06) wide, occupying 38-58% (48%) of proglottis width in mature proglottides. Internal seminal vesicle coiled, ejaculatory duct a little longer than half length of cirrus pouch; cirrus short probably aspinose. Vas deferens highly coiled anterior to posterior end of cirrus sac, extending to the middle of proglottis. Genital pores irregularly alternated, situated chiefly on medial part of proglottis, but can be observed below the middle part of proglottis at 54-62% (58%) from anterior end of mature and gravid proglottides. Cortical and dorsal ovary with two lobes, 0.04-0.13 (0.08) long and 0.08-0.33 (0.20) wide, the lateral ovarian lobes overlap the osmoregulatory ducts laterally. Vagina not ciliated internally, always posterior to cirrus, with poorly developed sphincter. Vaginal duct dorsal to uterus, seminal receptacle present. Mehlis' gland 0.02-0.06 (0.04) in diameter. Compact cortical vitellaria, arranged in two lateral rows, extending to the whole proglottis length. Pre-formed cortical uterus early occupying only the porterior part of proglottis, with 18-28 (22) lateral branches per side. Eggs with external delicate membrane, 0.0275 in diameter, embryophore 0.0200 in diameter, oncosphere 0.015 in diameter. Final proglottids lacking eggs.
Taxonomic and ecological summary
Host: Pimelodus ornatus Kner, 1857
Locality: Porto Rico, Paraná River, State of Paraná, Brazil.
Site of infection: intestine
Prevalence: 75% (28 fishes examined, 21 parasited)
Mean intensity of infection: 9
Specimens deposited: Instituto Oswaldo Cruz Collection (CHIOC) Nos 33679a (holotype) and 33679 b-d (paratypes)
Etymology: the name of the species is a reference to the popular name of the host.
Remarks: the genus Spasskyellina established by Freze (1965) is chiefly characterized by suckers with spines, pre-formed uterus with slightly developed lateral diverticula and reproductory organs and vitelline in the cortical region. According to Rego and Pavanelli (1992) there are two species of the genus Spasskyellina: S. lenha (Woodland, 1933) and S. spinulifera (Woodland, 1935). Brooks (1995) presented the phylogenetic hypothesis for the Monticelliidae. In that hypothesis, S. lenha and S. spinulifera were considered sister species based on the presence of spinose suckers. Furthermore S. spinulifera wasdifferentiated from S. lenha by having an average of 60 rather than 200 testes per proglottis, an apomorphic reduction in testes number within the Monticelliinae. Taking our study as a basis, we suggest the following improvements to that hypothesis. First, we agree that S. lenha and S. spinulifera are sister species; however, we recognize Spasskyellina as a distinct genus, and not part of Monticellia as proposed by Brooks (1995), on the basis of two synapomorphies: (1) spinose suckers and (2) the vagina being always posterior to the cirrus sac rather than alternating irregularly anteriorly and posteriorly. This leaves Monticellia as a genus without a synapomorphy and containing only two species: M. coryphicephala and M. megacephala. Second, we consider S. lenha to be the sister species of S. spinulifera plus S. mandi n. sp., which are linked by an apomorphic reduction in number of testes. S. lenhaexhibits secondary folds on the tegument of the strobila, an apparent autapomorphy for that species. Furthermore, S. spinulifera has vitellaria in the ventral rather than lateral cortex, an autapomorphy for that species, and S. mandi n. sp. has an average of 36 rather than 60 testes per proglottis, and unusually large ventral osmoregulatory ducts, both of these traits being apparent autapomorphies for the new species. S. mandi n. sp. is also characterized by excretory canals with a large diameter, approximately 0.05 mm, which is not found in the other species of the same genus. Besides, the genital pores open in the middle or slightly after the middle half of the proglottids, a characteristic which is not found in the two other species.
Freze (1965) and Rego (1994) stated that a characteristic of Spasskyellina is a uterus with slightly developed lateral diverticula. However the new species presented a uterus with a well developed lateral diverticula; moreover the three species of Spasskyellina has the vagina always posterior to cirrus sac. Thus it becomes necessary to emend the generic diagnosis of Spasskyellina given by Freze (1965) to include these feature.
To Dr Amilcar A Rego, Instituto Oswaldo Cruz, Rio de Janeiro, RJ, Brazil for the critical revision of the manuscript.
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