Corresponding author: Voitto Haukisalmi (
Academic editor: B. Georgiev
A new species of tapeworm,
Haukisalmi V, Konyaev S, Lavikainen A, Isomursu M, Nakao M (2016) Description and life-cycle of
Morphological differences between independent species of the genus
A recent molecular phylogenetic study on
Since the report by
The material used in the description of the new species consisted of 14 adult specimens: seven from
In addition, 11 metacestodes (cysticerci) were examined to characterize the rostellar hooks of the new species: two specimens from the European roe deer
Conspecificity of adults and metacestodes in various host species was confirmed using a partial nucleotide sequence (396 bp) of the mitochondrial cytochrome Kimura 2–parameter
Adult cestodes were relaxed in water and fixed flat (without pressure) and preserved in 70–75% ethanol. Fragments of each specimen, representing various developmental stages, were stained with alum carmine, cleared in eugenol and mounted in Canada balsam. Hand–cut transverse sections of mature proglottids were prepared to determine the number of dorso–ventral testicular layers and the dorso–ventral position of terminal genital ducts with respect to the longitudinal ventral osmoregulatory canals and the nerve cord.
Cysticerci were fixed and preserved in 70–75% ethanol. The hook crowns extracted from cysticerci were mounted in Berlese’s medium for study. Only hooks aligned well in the horizontal plane were used for the morphometric analysis.
Five linear measurements, as defined by (total length) (total width) (posterior length) (anterior length) (guard length)
Variation in measurements (µm) of large rostellar hooks in
Hosts, region |
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168–228 (195.9) | 78–94 (84.5) | 114–162 (133.8) | 76–97 (86.3) | 42–54 (47.7) | |
214–231 (223.4) | 79–96 (89.4) | 138–162 (152.1) | 87–101 (94.9) | 40–59 (50.8) | |
168–231 (212.2) | 78–96 (87.4) | 114–162 (144.7) | 76–101 (91.4) | 42–59 (49.5) | |
213–222 (216.5) | 85–92 (87.5) | 136–153 (144.2) | 95–98 (96.9) | 48–56 (49.9) | |
215–238 (230.7) | 94–109 (103.4) | 148–171 (162.7) | 92–111 (104.3) | 54–88 (65.6) | |
213–230 (222.3) | 82–97 (90.9) | 145–162 (154.8) | 86–100 (94.0) | 46–60 (52.3) | |
Cervids, combined (n=25) | 213–238 (225.9) | 82–109 (97.2) | 136–171 (157.2) | 86–111 (100.3) | 46–88 (59.2) |
168–238 (219.1) | 78–109 (92.3) | 114–171 (150.9) | 76–111 (95.8) | 40–88 (54.4) |
The shape of the large rostellar hooks was compared by scaling a representative hook of each species to the same total length, and then aligning a pair of hooks using the outline of the junction between the blade and the guard as an anchor region. The form of the anchor region was almost invariable among the species considered here.
Type and voucher specimens have been deposited in the Finnish Museum of Natural History Institute of Systematics and Ecology of Animals SB RAS, Novosibirsk, Russia
DNA sequences showed unambiguously that the specimens from various host species and regions represent the same species. Four
A phylogenetic tree of selected species of
Voucher material from
Voucher material from
Other museum specimens from
Other records from
Salo, Perniön Ylikulma (WGS 84:
Site. Small intestine.
Host: European roe deer
N16553, Museum of All–Russian K. I. Skryabin Scientific Research Institute of Helminthology (Moscow),
Site. Liver and lungs.
Adults and metacestodes of
Measurements are in micrometres if not otherwise stated.
Mature proglottids of
Scolex (
Terminal genital ducts of
Outline drawings of large and small rostellar hooks of
Large and small rostellar hooks of
Hook crown of
Medium–sized species of
Rostellum bearing two rows of hooks; rostellar armature usually incomplete in adult specimens. In combined material, length of large hooks 168–231 (mean=212.2, n=27) and length of small hooks 106–137 (mean=126.2, n=25). Total length and other dimensions of large hooks consistently smaller in specimens from Finland than in those from Siberia and Russian Far East. Large hooks characterized by long, thick and straight handle sometimes provided with apical bulge, relatively short, wide and strongly curved blade and prominent, usually slightly pointed guard. Border between hidden and exposed parts of large hooks marked with distinct oblique ridge. Margin of ridge provided with pits of various sizes at middle of handle; similar but less distinct pits sometimes present at guard portion of ridge.
Proglottids craspedote, but velum poorly developed. Mature proglottids 2.8–5.3 mm (mean=4.3 mm, n=15) wide and 2.0–3.4 mm (mean=2.6 mm, n=15) long, with length/width ratio of 1:1.2–2.6 (mean=1:1.7, n=15) in well–relaxed specimens. Proglottids becoming more elongate posteriorly; fully–gravid proglottids up to 14 mm long, with length/width ratio of 1:4.7.
Genital pores irregularly alternating, positioned in middle of lateral margin of proglottids. Genital atrium weak, usually not protruding, 238–425 (mean=302, n=12) wide at base and 144–264 (mean=186, n=12) deep. Ventral longitudinal osmoregulatory canals 34–110 (mean=75, n=13) wide in mature proglottids, up to 200 in postmature/pregravid proglottids; connected by narrower transverse canals. Dorsal osmoregulatory canals narrow (seen only in transverse sections), running medially to ventral longitudinal canals. Terminal genital ducts positioned between dorsal and ventral longitudinal osmoregulatory canal and dorsal to nerve–cord.
Testes 591–725 (mean=653, n=5) in number, 80–130 in largest diameter, positioned primarily in one dorso–ventral layer. Testicular field widely confluent anteriorly and occupying all parts of median field lacking female organs, except small well–defined region anterior to ovary. Continuous posterior testicular field absent, but sometimes individuals testes positioned posterior to or overlapping vitellarium. Antero–poral testicular field longitudinally as long as postero–poral field (as separated by vas deferens). Testicular field separated from ventral osmoregulatory canals by distinct free space laterally, anteriorly and posteriorly. Cirrus–sac elongate, 340–425 (mean=382, n=11) long and 153–179 (mean=166, n=11) wide in mature proglottids, usually not extending to longitudinal ventral canal; muscle layers of cirrus–sac well–developed. Distal part of ductus cirri armed with delicate hair–like structures. Vas deferens forming few irregular loops inside cirrus–sac, prominently convoluted outside cirrus–sac.
Ovary bilobed, 98–172 (mean=150, n=15) wide and 57–103 (mean=84, n=15) long; lobes of roughly equal size, but antiporal lobe extending slightly more anteriad than poral lobe; ovary does not reach midline of proglottid longitudinally. Vitellarium distinctly elongated transversely, 80–145 (mean=126, n=15) wide and 19–41 (mean=31, n=12) long, slightly narrower than ovary; lateral extremities usually pointed. Vagina opens posterior to male pore, provided by distinct sphincter ca. 5 from distal end of vagina; sphincter ca. 3 long and 6 wide; sphincter sometimes absent or incomplete (present on one side of vagina only). Copulatory part of vagina shorter than cirrus sac, thick–walled, distinctly widened, curved posteriorly; maximum width of copulatory part 94–111 (mean=106, n=10). Proximal vagina narrow, of uniform width, runs posterior to vas deferens, usually slightly undulating, rarely looped. Lumen of vagina lined with delicate hair–like structures almost throughout its length; hairs particularly long in widened copulatory part. Prior to joining seminal receptacle, vagina forms differentiated region, 10–12 long, with tapered lumen lacking hairs. Sperm–filled seminal receptacle elongate, 9–17 (mean=12.4, n=15) long. Mehlis’ gland spherical, 18–22 (mean=19.6, n=11) in diameter. Uterus in pre–gravid and early gravid proglottids with 8–11 primary branches on each side, often with secondary and tertiary bifurcations; lateral branches not reaching ventral osmoregulatory canal; terminal branches usually with multiple anterior or posterior sacculations. Eggs spherical or subspherical, with maximum diameter of 34–39 (mean=36.8, n=26) in whole–mounts. Outer egg shell thick (4.0–4.5), distinctly two–layered.
Metacestode is cysticercus. Ethanol–fixed cysticerci with fully–developed rostellar hooks 3–14 mm long and 2–5 mm wide; larger cysticerci with elongate or sac–like posterior bladder and, in one case, with short (8 mm) strobila between bladder and scolex region. Rostellum armed with 30–34 (mean=32.0, n=7) hooks forming two rows. Large hooks 213–238 (mean=225.9, n=27) and small hooks 123–145 (mean=136.7, n=23) long. Average hook dimensions are consistently smaller in specimens from Finland than in specimens from Siberia and Russian Far East. Rostellar hooks of metacestodes are similar in shape to those of adult cestodes.
Eurasia, from Finland to Russian Far East.
The specific epithet refers to the main definitive and intermediate hosts of the new species.
Host species and characteristics of rostellar hooks of
Definitive hosts | Intermediate hosts | Geographic distribution | Number of hooks | Large hooks, length | Small hooks, length | |
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bears ( |
cervids ( |
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canids | cervids and other ruminants | worldwide |
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felids ( |
unknown | Africa |
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148–151 | |
unknown, probably felids ( |
bovids ( |
Central Asia |
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unknown, probably cervids | Central Asia |
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canids | cervids and other ruminants | Holarctic region |
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felids ( |
lagomorphs | Eurasia | 58–66 | 370–420 | 150–247 | |
felids ( |
lagomorphs | America, Asia | 54–74 | 297–430 | 180–247 | |
felids ( |
cervids ( |
America | 38–44 | 223–297 | 165–223 | |
canids | cervids | Russia |
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felids ( |
cervids ( |
Siberia |
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canids, occasionally felids including |
lagomorphs | worldwide | 34–46 |
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felids ( |
unknown (probably lagomorphs) | America | 38–42 | 352–415 | 214–240 | |
felids ( |
bovids (antelopes), suids ( |
Africa | 32–49 | 223–273 | 142–199 | |
felids ( |
rodents | America | 36–46 | 238–258 | 145–198 |
When aligned using the outline of the junction between the blade and the guard, the large rostellar hooks of
Pairwise comparisons of the shape of the large rostellar hooks in
Interspecific differences in the morphology of mature proglottids between
Comparison of morphological features of mature proglottids in
Vaginal sphincter | Longitudinal extent of ovary | Antiporal lobe of ovary distinctly larger than poral lobe | Free space around testes | Length of poral testicular fields | Width of anterior testicular field | Number of testicular layers | |
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+ | < midline | – | + | A = P† | wide | 1 | |
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+ | > midline | + | – | A = P | wide | 2–3 |
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– | < midline | + | – | A > P | wide | 1 |
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+ | ≤ midline | – | ? | A = P | wide | 1 |
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+ | < midline | + | + | A > P | wide | 1–2 |
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+ | = midline | – | + | A < P | narrow | ? |
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– | < midline | + | – | A > P | wide | 2–4 |
A, antero–poral testicular field; P, postero–poral testicular field (as separated by terminal genital ducts).
In practice, the identification of
Total length has often been the only feature used to characterize the rostellar hooks of
The large hooks of the cestode from
Besides
A group of taeniid cestodes, including two species parasitizing felids [
The existing data on
The lynx and the roe deer have almost continent–wide, overlapping distributions in Eurasia, although the latter host is represented by two allopatric species (
However, despite the basically strict host–specificity, accidental infections of other definitive host species are likely to occur, especially with unrelated predators utilizing same intermediate host species. The present finding of
The finding of
It may be that infections of larger cervids (
Because
A survey of helminths of the lynx in Estonia (
The identification of
It is obvious that some of the existing reports of
Antti Oksanen (Finnish Food Safety Authority Evira) is acknowledged for support and shared enthusiastic attitude towards parasites of all kinds. We thank Minna Nylund (Evira) for collecting and preserving tapeworms from lynx. Pekka Spets, Esko Huuhtanen, Mikko Suomela and Valtteri Söderman kindly submitted the Finnish animal samples from which the parasites were found. Dr Seryodkin provided specimens of