Publications:
Caira, J. N. and C. P. Keeling. 1996. On the status of Pinguicollum (Tetraphyllidea: Onchobothriidae) with a redescription of P. pinguicollum. Journal of Parasitology 82: 423-430.
Caira, J. N., C. J. Healy and J. Swanson. 1996. A new species of Phoreiobothrium (Cestoidea:Tetraphyllidea) from the Great Hammerhead shark Sphyrna mokarran and its implications for the evolution of the onchobothriid scolex. Journal of Parasitology 82: 431-438.
Caira, J. N., K. Jensen, Y. Yamane, A. Isobe and K. Nagasawa. 1997. On the tapeworms of Megachasma pelagios: Description of a new genus and species of lecanicephalidean and additional information on the trypanorhynch Mixodigma leptaleum. In: Biology of the Megamouth shark. K. Yano, J. F. Morrissey, Y. Yabumoto and K. Nakaya (eds.) Tokai University Press, Tokyo, Japan. pp. 181-191.
Nasin, C., J. N. Caira and L. Euzet. 1997. A revision of Calliobothrium (Tetraphyllidea: Onchobothriidae) with descriptions of three new species and a cladistic analysis of the genus. Journal of Parasitology 83: 714-733.
McKenzie, V. and J. N. Caira. 1998. Three new genera and species of tapeworms from the longnose sawshark, Pristiophorus cirratus, with description of their modes of attachment to the spiral intestine. Journal of Parasitology 84: 409-421.
Caira, J. N. and R. Rasolofonirina. 1998. A new species of Pedibothrium (Cestoidea: Tetraphyllidea) from the short-tail nurse shark, Pseudoginglymostoma brevicaudatum (Elasmobranchii: Orectolobifromes), from Southwest Madagascar. Journal of the Helminthological Society of Washington 65: 50-55
Caira, J. N., K. Jensen and C. J. Healy. 1999. On the phylogenetic relationships among tetraphyllidean, lecanicephalidean and diphyllidean tapeworm genera. Systematic Parasitology 42: 77-151.
Olson, P. D. and J. N. Caira. 1999. Evolution of the major lineages of tapeworms (Platyhelminthes: Cestoidea) inferred from 18S ribosomal DNA and Elongation factor 1a. Journal of Parasitology 85: 1134-1159.
Olson, P. D., T. R. Ruhnke, J. Sanney, T. Hudson. 1999. Evidence for host-specific clades of tetraphyllidean tapeworms (Platyhelminthes: Eucestoda) revealed by analysis of 18S ssrDNA. International Journal for Parasitology 29: 1465-1476.
Tyler, G. A. and J. N. Caira. 1999. Two new species of Echinobothrium (Cestoidea: Diphyllidea) from myliobatiform elasmobranchs in the Gulf of California, México. Journal of Parasitology 85: 327-335.
Faliex, E., G. Tyler, and L. Euzet. (in press). A new species of Ditrachybothridium (Cestoda: Diphyllidea) from Galeus sp. (Selachii, Scyliorhynidae) from the South Pacific Ocean, with a revision of the diagnosis of the order, family and genus and notes on descriptive terminology of microtriches. Journal of Parasitology 86: 000-000.
Caira, J. N., K. Jensen and C. J. Healy. (accepted). Interrelationships among tetraphyllidean and lecanicephalidean cestodes. In Interrelationships of the Platyhelminthes, D. T. J. Littlewood & R. Bray (eds.), Taylor & Francis, London. (60 ms pages).
Ghoshroy, S. and J. N. Caira. (submitted). Four new species of Acanthobothrium from the whiptail stingray (Dasyatis brevis). Journal of Parasitology.
Presentations:
Jensen, K., J. N. Caira, and C. J. Healy. Are all apical structures a like? On the homology among apical structures of selected elasmobranch cestodes. 72nd Annual Meeting of the American Society of Parasitologists. Nashville, U.S.A. 1997. Oral presentation.
Healy, C. J., K. L. Tiekotter, and K. Jensen. On the formation of segments and pseudosegments in the litobothriideans. 72nd Annual Meeting of the American Society of Parasitologists. Nashville, U.S.A. 1997. Oral presentation.
Tyler, G. and J. N. Caira. Analysis of hook proteins in five orders of cestodes, with comments on hook isolation techniques. 72nd Annual Meeting of the American Society of Parasitologists. Nashville, U.S.A. 1997. Oral presentation.
Jensen, K. and J. N. Caira. The identity of the spotted eagle ray, Aetobatus narinari - a parasitological perspective. 14th Annual Meeting of the American Elasmobranch Society. Guelph, Canada. 1998. Oral presentation.
Healy, C. J. and J. N. Caira. Identifying cryptic carcharhiniform shark species: Tapeworms as diagnostic tools. 14th Annual Meeting of the American Elasmobranch Society. Guelph, Canada. 1998. Oral presentation.
McKenzie, V. J. Phyllobothriid cestodes of shraks from the Gulf of California. Symposium on the metazoan parasites of elasmobranchs from the Gulf of California. 73rd Annual Meeting of the American Society of Parasitologists. Kona, Hawai'i, U.S.A. 1998. Invited talk.
Jensen, K., J. Caira and C. Healy. Comaparative morphological study of apical stuctures of selected elasmobranch cestodes. IXth International Congress of Parasitology. Makuhari Chiba, Japan. 1998. Oral presentation.
Healy, C. J., K. Tiekotter and K. Jensen. Investigations into the strobilar morphology and nature of segmentation in litobothrideans. IXth International Congress of Parasitology. Makuhari Chiba, Japan. 1998. Oral presentation.
Tyler, G. Systematics
and host associations in the cestode order
Diphyllidea. Oral
communication. 74th Annual Meeting of the American Society of
Parasitologists, Monterey, California. 1999.
Abstracts:
The identity of the spotted eagle ray, Aetobatus narinari - a parasitological perspective. Kirsten Jensen and J. N. Caira.
14th Annual Meeting of the American Elasmobranch Society. Guelph, Canada. 1998. Oral presentation.
Spiral intestines of rays
identified as Aetobatus narinari, from the Gulf of
California, the Gulf of Thailand and the Timor Sea were examined
for tapeworms. Light and electron microscopy of these worms
revealed faunal differences among individuals from these
localities. Rays from México hosted several different
species in the order Tetraphyllidea. Rays from Thailand and
Australia hosted species belonging to the order Lecanicephalidea,
but, the species of lecanicephalideans differed between the two
localities. Although these differences may simply reflect
differences in intermediate host availability, it is possible that
these data are indicative of differences in the specific
identities of the rays. Host morphology seems to support the
latter explanation. Although rays from all three localities
exhibited dark dorsal surfaces with white spots, size and
distribution of these spots differed substantially. Additional
differences were seen in the angle of the anterior margin of the
pectoral fins and in snout length. Combined these data lead us to
suspect that the spotted eagle ray found in the Eastern Pacific
might not be conspecific with that found in the Western Pacific
and Indian Oceans. In addition, based on our data, the specific
identity of the spotted eagle ray from the Western Pacific and
Indian Oceans is suspect.
Identifying cryptic carcharhiniform shark species: tapeworms as diagnostic tools. Claire J. Healy and J. N. Caira
14th Annual Meeting of the American Elasmobranch Society. Guelph, Canada. 1998. Oral presentation.
Tetraphyllidean tapeworms are restricted to
elasmobranch hosts and can be highly host specific; in fact, some
species parasitize single species of elasmobranch and thus may
assist in identifying elasmobranch species. Spiral intestines of
Prionace glauca, Galeocerdo cuvier, Eusphyra
blochii, 4 Sphyrna species, 2 Negaprion species,
3 Rhizoprionodon species, and 19 Carcharhinus
species from locations including the western North Atlantic Ocean,
Gulf of California, and Timor Sea off of northern Australia were
examined for tetraphyllideans in the family Onchobothriidae.
Species of the genera Dicranobothrium,
Phoreiobothrium, and Platybothrium were found to be
restricted in distribution to carcharhiniform sharks and were
found in most of the species examined. Many of the onchobothriids
found are new to science and currently undescribed. Our results
suggest that the host species examined are parasitized by at least
1 strictly host specific onchobothriid species. In some cases,
more than 1 host specific onchobothriid species was found in a
single host species. For example, Negaprion acutidens
hosted 3 new species of Phoreiobothrium that were not found
in the other 30 species of carcharhiniform sharks examined. These
results suggest that each carcharhiniform species may possess a
unique parasite fauna that could be used as a diagnostic tool for
species identification.
On the formation of segments and pseudosegments in litobothrideans. Claire J. Healy, Kenneth L. Tiekotter and Kirsten Jensen
72nd Annual Meeting of the American Society of Parasitologists. Nashville, U.S.A. 1997. Oral presentation.
The litobothrideans are a relatively small
group of tapeworms that parasitize elasmobranchs. Although they
possess reproductive morphology that is tetraphyllidean, they bear
nothing resembling the tetrafossate scolex of a typical
tetraphyllidean; rather, the apex of the strobila bears a sucker
which is followed by a number of pseudosegments, the anteriormost
of which are cruciform with dorsal and ventral muscular
extensions. Our objective was to determine the nature and site of
segment and pseudosegment formation in order to facilitate an
understanding of the homologies between the tetraphyllidean and
litobothridean strobilae. Material examined included adults and
juveniles of Litobothrium daileyi and adults of L.
amplifica which were obtained from Alopias pelagicus,
and a new species of Litobothrium which was obtained from
Alopias superciliosus in the Gulf of California. Whole
mounts and longitudinal sections of these three
Litobothrium species were prepared and stained with a
variety of stains including acetocarmine with ferric chloride and
Verhoeff's ferric hematoxylin and examined using light microscopy.
All three Litobothrium species were also prepared and
examined using scanning electron microscopy in order to study the
pattern of the strobila microtriches. The results of the selective
staining protocols lead us to believe that there is one
germinative region located immediately posterior to a region of
non-cruciform pseudosegments in each Litobothrium species.
In addition, based on comparative examination of juvenile and
adult L. daileyi, we hypothesize that the germinative
region produces both the reproductive segments posterior to it and
the pseudosegments anterior to it.
Collection of elasmobranchs and their metazoan parasites from the Gulf of California: Project logistics. Kirsten Jensen
Symposium on the metazoan parasites of elasmobranchs from the Gulf of California. 73rd Annual Meeting of the American Society of Parasitologists. Kona, Hawai'i, U.S.A. 1998. Invited talk.
Two collecting expeditions were made to the
Gulf of California, México, the first from June to October
of 1993, the second from May to August of 1996. Twenty-seven
people assisted with the collections during the 16 total weeks of
field work. A total of 766 elasmobranchs were collected from the
Gulf in the vacinity of 6 localities along the eastern coast of
the Baja Peninsula from Puertecitos in the north to San Jose del
Cabo in the south. Elasmobranchs were obtained in collaboration
with local Mexican fishermen using nets, longlines or spears. The
sharks, skates and rays examined represented 42 different species
in 13 families (after Shirai, 1996). Thirty of these species are
restricted to the Eastern Pacific Ocean. A systematic protocol was
followed for each elasmobranch necropsied: Individuals were
photographed, measured and identified. External body surfaces and
orifices were examined for ectoparasites. All internal cavities
and organs were examined for endoparasites. All parasites were
removed and fixed as appropriate for each group. Often whole
organs such as gills, olfactory bulbs and spiral intestines were
fixed and kept for further detailed examination. When feasible,
host liver samples were taken and preserved in ethanol. Upon
return to the lab parasites were sorted taxonomically and
distributed to appropriate collaborating taxonomists. Elasmobranch
identification was one of the most difficult aspects of the
project. The ND2 gene was sequenced to facilitate identification
of some individuals in the shark genera Mustelus and
Carcharhinus, and the ray genera Gymnura,
Mobula, Rhinobatos, Urobatis and
Myliobatis. Results from this project suggest the existence
of several presumably unrecognized host species in this geographic
region. (Collections were made under the Mexican collecting permit
No. 120496-213-03 issued by the Secretaria de Medio Ambiente
Recursos Naturales y Pesca; supported by NSF Grant DEB 9521943
awarded to J. N. Caira and G. W. Benz)
Litobothridean and lecanicephalidean cestodes from the Gulf of California. P. D. Olson and Kirsten Jensen
Symposium on the metazoan parasites of elasmobranchs from the Gulf of California. 73rd Annual Meeting of the American Society of Parasitologists. Kona, Hawai'i, U.S.A. 1998. Invited talk.
Records of members of the order Litobothridea
to date are restricted to localities from the Pacific Ocean. No
previous records of litobothrideans from the Gulf of California
exist. In the present study three litobothridean species were
found: Litobothrium amplifica and L. daileyi
from the pelagic thresher shark (Alopias pelagicus) and
what appears to be a new species of Litobothrium from the
bigeye thresher shark (A. superciliosus). These data
combined suggest that the identity of the type and only known host
individual of the former two species, a bigeye thresher shark
collected from the western coast of México, may be in
error. The order Lecanicephalidea is a group of cestodes
parasitizing primarily rays. Until the present study, there has
been no account of lecanicephalideans from the Gulf of California.
We discovered lecanicephalideans in ray species belonging to 2
families: Myliobatidae (bat rays) and Squatinidae (angle sharks).
A new lecanicephalidean genus was discovered from the ray
Mobula japonica and 2 species of Tylocephalum from
Rhinoptera steindachneri. In addition, Myliobatis
longirostris and M. californicus each hosted new
species of 'Discobothrium' (sensu Brooks). A third new
species of 'Discobothrium' was discovered in the angle
shark, Squatina californica. Surprisingly, no
lecanicephalideans were found in any of 10 spotted eagle rays
(Aetobatus narinari) examined, while up to 4
lecanicephalidean species are known from this host species in the
Western Pacific Ocean. The absence of species of
Polypocephalus in rays examined from the families
Dasyatidae (diamond rays) and Rhinobatidae (guitarfishes) was also
surprising given their frequent occurrence in rays belonging to
these families in other localities.
Are all apical structures alike? On the homology among apical structures of selected elasmobranch cestodes. Kirsten Jensen, J. N. Caira, and Claire J. Healy
72nd Annual Meeting of the American Society of Parasitologists. Nashville, U.S.A. 1997. Oral presentation.
Apical structures, defined as modifications of
the apex of the scolex, are found in 8 of the 12 orders of
cestodes. The emphasis of this study is on the apical structures
of cestodes of the orders Tetraphyllidea and Lecanicephalidea,
with some consideration of apical structures in the Diphyllidea
and Trypanorhyncha in the hope of providing a framework for the
determination of homologies among these structures in all 8
cestode orders. The apical structures in the Lecanicephalidea and
Tetraphyllidea can take on a variety of forms which is reflected
in the extensive terminology available to describe these
structures, e.g. myzorhynchus, metoporhynchus, muscular disc, etc.
To facilitate phylogenetic analysis it is essential to determine
homologies among these apical structures. The apical structures of
5 lecanicephalidean and 3 tetraphyllidean species were
investigated using light microscopy of whole mounts and
histological sections, and scanning electron microscopy. The
resulting positional and structural data were used in conjunction
with developmental data to identify independent components of
apical structures. We propose that apical structures in larvae and
adults are homologous within and between the two orders. We
distinguish apical structures from apical organs: Apical
structures are modifications of the apex of the scolex and can be
either invaginable (Echeneibothrium), retractable
(Tetragonocephalum), or not changeable in position
(Hornellobothrium). The surface of apical structures can be
either secretory (Tylocephalum) or not
(Corrugatocephalum). Some groups possess an apical organ in
addition to an apical structure. We define the apical organ as a
further elaboration, housed by the apical structure. Apical organs
are can be divided (tentacles of Polypocephalus) or
undivided (Hornellobothrium). We believe that at least some
of these characters are applicable to the apical structures of the
other 8 cestode orders as well.
The remaining tetraphyllideans and some unusual cestode taxa from elasmobranch hosts in the Gulf of California. Claire J. Healy
Symposium on the metazoan parasites of elasmobranchs from the Gulf of California. 73rd Annual Meeting of the American Society of Parasitologists. Kona, Hawai'i, U.S.A. 1998. Invited talk.
Two unusual cestode taxa were collected from
the Gulf of California. The first taxon, from Rhinoptera
steindachneri, is represented by a single, immature specimen
that can be provisionally placed in the Phyllobothriidae but is
unique from all currently described phyllobothriid taxa. The
second taxon, from Alopias pelagicus, remains identified
only as a cestode because it lacks diagnostic scolex features and
all segment anatomy. New geographic records were established for
Prosobothriidae, Disculicipitidae, and Cathetocephalidae with the
following: a Prosobothrium species from Sphyrna
lewini, a new species of Disculiceps from Prionace
glauca (new host record), and Catheotcephalus
thatcheri from Carcharhinus leucas. Thysanocephaline
species included Thysanocephalum crispum from Galeocerdo
cuvier and 2 new Thysanocephalum species from S.
lewini. Four onchobothriid genera, aside from
Acanthobothrium, were represented in the collections.
Pedibothrium brevispine and Pedibothrium manteri
were collected from Ginglymostoma cirratum. Five
Calliobothrium species were collected from Mustelus
species: C. riseri from M. henlei and M.
californicus (new host record), C. evani from M.
lunulatus and M. californicus (new host record), C.
pellucidum and a new species of Calliobothrium from
M. californicus, and a new species of Calliobothrium
from M. lunulatus. Four Platybothrium species were
collected: P. auriculatum from Prionace glauca,
P. cervinum and a new species of Platybothrium from
C. leucas (new host record for P. cervinum), and
P. parvum from S. lewini (new host record) and S.
zygaena. Six new Phoreiobothrium species were found in
carcharhiniform hosts including S. lewini, S.
zygaena, Carcharhinus falciformis, C. limbatus,
and C. leucas. Four additional Phoreiobothrium
species were collected: P. exceptum and P.
pectinatum from S. zygaena and S. lewini (new
host record), P. c.f. triloculatum from C.
leucas, and a species of Phoreiobothrium from
Carcharhinus porosus. For T. crispum and all
previously described onchobothriids except the
Calliobothrium species, these collections represent new
geographic records.
Comparative morphological study of apical structures of selected elasmobranch cestodes. Kirsten Jensen, J. N. Caira and Claire J. Healy
IXth International Congress of Parasitology. Makuhari Chiba, Japan. 1998. Oral presentation.
The scolex in representatives of 8 of the 11
orders of cestodes bears an apical attachment structure. The
degree of homology among these apical structures in these taxa is
not clearly understood. To facilitate phylogenetic analysis an
understanding of these homologies is essential. The apical
structures of species representing 5 lecanicephalidean genera, 2
tetraphyllidean genera, 2 diphyllidean genera, 1 trypanorhynchan
genus and 1 proteocephalidean genus were investigated as whole
mounts and histological sections using light microscopy, and with
scanning electron microscopy. Resulting structural data, in
conjunction with positional and developmental data, were used to
assess potential homology of the different apical structures.
These data suggest that, collectively, the species examined
exhibit two different, independent components of apical
structures: an apical modification of the scolex proper, and an
apical organ. In apical modifications of the scolex proper the
apex of the scolex is modified but continuous with the scolex
proper (e.g. the myzorhynchus in Echeneibothrium). Often
these structures are conical extensions bearing spiniform
microtriches. Excretory ducts are seen throughout this region.
Apical organs, however, are separated from the scolex proper by a
discrete boundary (e.g. the metoporhynchus in Tylocephalum,
the tentacles in Polypocephalus). Apical organs lack
excretory ducts. Some taxa possess only one of the two structures;
most taxa, however, possess both. Both apical modifications of the
scolex proper and apical organs vary in form among taxa. This
variation can be categorized using the following criteria:
invaginability, retractability, glandularity, muscularity and the
presence of an aperature. We believe that at least some of these
characters are applicable to the apical structures of members in
other orders of cestodes.
The cestode order Diphyllidea: systematics and host associations. Gaines Tyler
IXth International Congress of Parasitology. Makuhari Chiba, Japan. 1998. Oral presentation.
The order Diphyllidea is a small, poorly
understood group of eucestodes. Its members are found parasitizing
a variety of elasmobranch fishes, primarily batoids. The order is
composed of 31 species in three genera, Echinobothrium,
Ditrachybothridium and Macrobothridium. A recent
phylogenetic analysis of representative species of these three
genera using 120 characters obtained from light and scanning
electron microscopy (SEM) supports the monophyly of the order,
with Echinobothrium and Macrobothridium as sister
genera, and Ditrachybothridium as the more distant basal
member of the group. The order is characterized primarily by the
presence of a scolex possessing two bothria, with palmate
microtriches covering the exteral surfaces. This form of
microtrich has to date been observed in nine of ten diphyllidean
species examined using SEM. Among these three genera,
Macrobothridium species demonstrate the highest degree of
host fidelity, parasitizing elasmobranchs of the genus
Rhynchobatus. Species of Echinobothrium are found primarily
in batoids of the family Rajidae, but has also been reported from
triakid sharks. The majority of the species found in sharks are
unique in their possession of a secondary "corona" of spines on
the scolex. Species of Ditrachybothridium are found
parasitizing both rajids and scyliorhinid sharks. However, the
degree of development of specimens of Ditrachybothridium
species found in these two host groups indicates that
scyliorhinids may be the natural hosts for members of the genus.
The correlation between parasite and host phylogenies (sister
genera Echinobothrium and Macrobothridium
parasitizing the rajids and rhynchobatids respectively, and the
more distant Ditrachybothridium parasitizing the basal
galeomorph sharks) indicates the possibility of host parasite
coevolution in this system. However, if this is the case, the lack
of diphyllideans in the majority of the other elasmobranch species
belonging to these two groups will need to be
addressed.
Diphyllidean cestodes from the Gulf of California. Gaines Tyler
Symposium on the metazoan parasites of elasmobranchs from the Gulf of California. 73rd Annual Meeting of the American Society of Parasitologists. Kona, Hawai'i, U.S.A. 1998. Invited talk.
Cestodes of the order Diphyllidea were entirely
unknown from the Gulf of California, and only very poorly known
from the Pacific Ocean in general, prior to our survey of the
parasites of the elasmobranchs of the Gulf of California. The
order Diphyllidea is composed of three genera,
Echinobothrium, Ditrachybothridium and
Macrobothridium whose species were previously known to
parasitize 14 genera of batoids in the families Rajidae,
Myliobatidae, Rhinobatidae, Rhynchobatidae and Dasyatidae, and
three genera of sharks in the families Scyliorhinidae and
Triakidae. Eleven species representing only 6 of these 17 genera
of hosts were collected in this survey. Echinobothrium was
the only diphyllidean genus found during this survey. The lack of
suitable hosts for Macrobothridium (rhynchobatid batoids)
and Ditrachybothridium (scyliorhinid sharks) in the Gulf of
California is the likely explanation for the lack of these 2
genera from the region. Echinobothrium species were found
in Myliobatis californicus, Myliobatis longirostris,
Rhinoptera steindachneri, Rhinobatos leucorhynchus
and Urobatis maculatus. Each of these host species was
parasitized by a single species of Echinobothrium, with the
two species of Myliobatis sharing a common
Echinobothrium species. Each of these four species of
Echinobothrium is new to science, and also represents a new
host record. In addition, the discovery of Echinobothrium
in Urobatis maculatus broadens the host distribution for
species of the order to include the family Urolophidae. The small
number of diphyllidean species collected in this survey may
suggest that this order is only weakly represented in the Gulf of
California. However, when compared to other geographic regions,
the Gulf of California has one of the richest assortments of
diphyllideans, rivaled only by that of Australia and New Zealand
in the South Pacific Ocean.
Acanthobothrium diversity in elasmobranchs from the Gulf of California. Sohini Ghoshroy
Previously 24 species of Acanthobothrium have been reported from the sharks, skates and rays of the eastern Pacific Ocean, but none of these records include the Gulf of California. In the present study, 21 species of elasmobranchs belonging to eight families were found to harbour one or more species of Acanthobothrium in the Gulf of California. Among the six orders of elasmobranchs examined, Acanthobothrium was restricted to hosts belonging to the two orders, Heterodontiformes and Rajiformes. Species in thirteen of the fourteen genera in these two orders were parasitized; the only exception was the genus Mobula. None of the four species of Mobula examined hosted Acanthobothrium. This absence could be the result of the filter feeding nature of these rays. Conservatively these 21 species of elasmobranchs hosted a total of 45 species of Acanthobothrium, the majority of which appear to be new to science. The mean number of species of Acanthobothrium per host species was two, but this number ranged from one, in sharks such as Heterodontus mexicanus, to five, in rays such as Urobatis concentricus. Congeneric hosts were generally found to host different species of Acanthobothrium, even in sympatry. This preliminary study suggests a rich diversity of Acanthobothrium in elasmobranchs in the Gulf of California, which merits further investigation.
Investigations into the strobilar morphology and nature of segmentation in litobothrideans. Claire J. Healy, Kenneth L. Tiekotter and Kirsten Jensen
IXth International Congress of Parasitology. Makuhari Chiba, Japan. 1998. Oral presentation.
The litobothrideans are a relatively small
group of tapeworms that parasitize elasmobranchs. They are
currently placed in the family Litobothriidae within the
Tetraphyllidea; however, there has been some discussion of their
affinities with the unusual lecanicephalidean genus
Eniochobothrium, due to different interpretations of the
anterior region of the body. In order to define homologous
anterior regions among these groups, we sought to study
litobothridean morphology. Material examined included adults and
juveniles of Litobothrium daileyi and a new species of
Litobothrium both from Alopias superciliosus, adults
of L. amplifica from Alopias pelagicus, all from the
Gulf of California, and adults of Eniochobothrium sp.,
obtained from Rhinoptera sp. from Fog Bay, Australia. The
study taxa were examined as whole mounts and cross and
longitudinal sections prepared with a variety of stains using
light microscopy, and scanning electron microscopy. Longitudinal
sections revealed that although segmental boundaries are present
between all anterior segments of Eniochobothrium sp.,
segmental boundaries were lacking between several of the
anteriormost segments in the Litobothrium study species.
The bodies of extremely juvenile specimens of 2
Litobothrium species were found to consist of an apical
sucker, followed by 4 segments which, at that early stage, are
barely cruciform in shape, followed by the remnant of the
plerocercoid body. Our data suggest that the litobothridean study
species possess an anterior region, composed of an apical sucker
and the anteriormost segments which lack segmental boundaries,
that is homologous to tetraphyllidean and lecanicephalidean
scoleces. The more posterior litobothridean segments appear to be
true strobilar segments, much like all of the anterior segments
seen in the Eniochobothrium study species.
Sperm ultrastructure in three previously unexamined tetraphyllidean, lecanicephalidean and proteocephalidean cestode species. Claire J. Healy
74th Annual Meeting of the American Society of Parasitologists. Monterey Bay, California, U.S.A. 1999. Oral presentation.
Several taxonomic and phylogenetic studies have
questioned the current ordinal status of the Lecanicephalidea and
the Proteocephalidea, suggesting instead that members of these
orders are more correctly placed within the Tetraphyllidea. Sperm
ultrastructure can be a rich source of phylogenetic data, but such
data are only available for a few tetraphyllidean and
proteocephalidean taxa (6 and 4 species, respectively) and have
never been collected for any lecanicephalidean taxa. To increase
the knowledge of sperm morphology and spermiogenesis in these 3
groups, the following taxa were examined with transmission
electron microscopy (TEM): the tetraphyllidean, Calliobothrium
violae, from Mustelus canis in Long Island Sound,
United States, the lecanicephalidean, Tylocephalum sp. from
Aetomylaeus vespertilio in Buffalo Creek, Northern
Territories, Australia, and the proteocephalidean,
Proteocephalus sp. from Amia calva in Lake Ontario,
Canada. The tetraphyllidean specimens were fixed in 1.5%
glutaraldehyde and 1.5% paraformaldehyde; the lecanicephalidean
and proteocephalidean specimens were fixed in 10% formalin and
postfixed in 3% glutaraldehyde. All of the specimens were prepared
for TEM using conventional techniques, and testis and vas deferens
tissues were examined with a Phillips Transmission Electron
Microscope. Sperm morphology and spermiogenesis in C.
violae are consistent with what has been seen in other
tetraphyllidean (onchobothriid) species in terms of number and
arrangement of axonemes and arrangement of microtubules.
Determination of the states of sperm characteristics in the
lecanicephalidean and proteocephalidean species may further
illuminate the issue of the interrelationships of these
taxa.