Chelodina Oblonga Research Articles

Long‐term habitat degradation affects nest site selection behaviour by a freshwater turtle (Chelodina oblonga) in Western Australia

Abstract Freshwater turtles are one of the most endangered vertebrate groups with >60% of species threatened globally. Terrestrial nesting habitat degradation is a major threat to freshwater turtles, but the characteristics of nesting habitat remain poorly understood. This study investigated the nest site selection of the southwestern snake‐necked turtle (Chelodina oblonga) to improve the conservation prospects for this species in an urbanized wetland area. In total, 235 depredated and 86 non‐depredated nest sites and 320 non‐nest locations were surveyed at Bibra Lake, Western Australia, during the Austral spring–summer, 2018–2023. A suite of environmental variables was measured at nest sites and non‐nest locations. Analysis of similarities was used to determine whether nest sites and non‐nest locations differed in their environmental characteristics. Generalized linear mixed models were used to identify environmental variables that best explained the nesting preferences. The environmental characteristics of nest sites differed from those of non‐nest locations, with turtles nesting mainly in remnant natural habitat with greater canopy cover. Turtles generally avoided nesting in modified environments such as lawns and impervious surfaces. Factors influencing nest site selection are probably associated with the conditions necessary for regulating incubation temperatures and ease of nest excavation. This study suggests that modification of terrestrial vegetation around wetlands is adversely affecting freshwater turtle recruitment by removing or altering preferred nesting habitat. Protection and restoration of natural habitats fringing urban wetlands is important for the conservation of remnant freshwater turtle populations, and local partnership projects can help to achieve this.

Climate change affects the early‐life history of a freshwater turtle in a severely drying region

AbstractFreshwater turtles are one of the most threatened vertebrate groups. Climate change is a major threat to these species, with impacts affecting all life‐history stages. There is currently a limited understanding of how changes in climate may alter the environmental triggers for hatching and emergence from the nests of freshwater turtle hatchlings. This precludes making predictions about how climate change may impact freshwater turtle recruitment success. The southwestern snake‐necked turtle (Chelodina oblonga) is endemic to south‐western Australia, a global biodiversity hotspot that has undergone severe climatic drying. Recruitment failure is thought to be occurring in many populations of the species. However, there is little understanding as to how environmental change may be influencing recruitment. This study aimed to: (1) determine the incubation duration and hatching and hatchling emergence success of C. oblonga, (2) determine if the species exhibits hatching or emergence synchrony and/or delayed emergence and (3) quantify the effects of temperature and rainfall on hatchling emergence. Using this information, the study assesses how climatic drying and warming may be impacting C. oblonga's early life‐history. Between 2018 and 2020 nest sites were monitored around a large urban wetland with weekly assessments of egg and hatchling status. Incubation duration and hatching and hatchling emergence success were calculated, and generalized linear models were built to determine how temperature and/or rainfall predicted emergence. Hatchlings either emerged shortly after hatching or overwintered in the nest, and both hatching and emergence were asynchronous. Both emergence periods were positively associated with temperature and rainfall. This study reveals that incubation duration, hatching success, hatchling emergence and survival are all likely to be impacted by recent and projected climate change, and especially drying. Warming and drying are predicted for many temperate regions globally, and it is therefore important that their impacts on the early life history of freshwater turtles be better understood.

Optimizing road underpass design to maximize use by a freshwater turtle (Chelodina oblonga)

Abstract Roads affect the connectivity of habitat and inhibit movements of animals as a result of road avoidance and road‐related mortalities. Freshwater turtles are particularly vulnerable to mortality on roads, as females must often cross them when they leave the aquatic environment to nest. Ecopassages designed to enable safe movement across roads by wild animals may be an effective measure to reduce adverse impacts. Limited information exists, however, on effective design criteria for freshwater turtles. A willingness‐to‐utilize study was used to assess factors that may influence the use of a tunnel underpass by the southwestern snake‐necked turtle (Chelodina oblonga), a species whose populations are declining, in part, through road‐related mortalities of nesting females. Female C. oblonga were sourced from an urban wetland and placed in an enclosure with exits of varying tunnel lengths (12 and 25 m) and lighting treatments (‘light’ and ‘dark’) to assess the conditions that would promote successful passage. Generalized linear modelling showed that light treatments had a significantly increased likelihood of successful and faster passage for both 12 and 25 m tunnels than the dark treatments. Tunnel length had no effect either on success or rate of passage. This study provides the first account of the factors that may optimize successful tunnel passage by C. oblonga to reduce road‐related mortality, contributing to the conservation and management of the species and freshwater turtles more generally.

Morphology of the lectotype of Chelodina oblonga Gray 1841 (Testudines: Chelidae).

Uncertainty about taxonomy and nomenclature of the Australian long-necked turtle Chelodina oblonga has ensued since its description by Gray in 1841. This has been due to the general nature of information about provenance of the lectotype specimen and the ostensible morphological similarity of the specimen to another taxon from northern Australia that confused Gray and many subsequent workers. The south-western Australian provenance of the specimen has recently been confirmed by Shea et al. (2020). The present paper provides a detailed consideration of morphology of the specimen and compares it with other specimens available to Gray and to larger series that are now available. The study elucidates morphological aspects that have underlain the history of confusion and it highlights a number of characters that consistently differentiate adults of the relevant taxa. These demonstrate that morphology of the C. oblonga lectotype conforms with the taxon from the south-west of Western Australia, as has also been confirmed by recently published investigations of mitogenomics and historical information about provenance of the lectotype.

Genetic characterisation of cercarial stages of Choanocotyle Jue Sue and Platt, 1998 (Digenea: Choanocotylidae) in a native Australian freshwater snail, Isidorella hainesii (Tryon).

Isidorella hainesii (Tryon, 1866) is a native freshwater snail, belonging to the family Planorbidae, commonly found on aquatic vegetation in south eastern parts of Australia. In the present study, we report natural infection with a species of Choanocotyle Jue Sue and Platt, 1998 (Digenea: Choanocotylidae) parasite in inland Australia for the first time, followed by characterisation of the parasite using both morphological and molecular approaches. Snails (n = 150) were collected from recently drained, natural ponds at a local fish farm located in the Riverina region, New South Wales, Australia. Parasites were subjected to preliminary morphological examination followed by DNA extraction to obtain their ITS-2, 18S and 28S sequences. Based on their sequence data and phylogenetic analyses they were identified as Choanocotyle hobbsi Platt and Tkach, 2003, which has only previously been described from Chelodina oblonga Gray, 1841 (snake-necked turtle) in Western Australia. Previous researchers suggested that in Australia, C. oblonga and its parasite fauna are separated from their eastern counterparts due to formation of impenetrable waterless desert in the country during the late Cretaceous. Our study extends the distribution of Choanocotyle hobbsi from Western Australia to the Murray Darling Basin in New South Wales, however, the definitive host remains unknown in New South Wales.

First record of predation of a hatchling turtle by the Western tiger snake (Notechis scutatus occidentalis).

ABSTRACT Snake-Turtle interactions have been rarely documented. We recorded a hatchling Chelodina oblonga within the stomach contents of a Western tiger snake (Notechis scutatus occidentalis). This is the first recorded observation of an interaction between snakes and hatchling freshwater turtles in Western Australia. Field based palpation failed to detect the hatchling, suggesting that without dissection, turtle hatchling predation by snakes more generally could be higher than commonly reported. Snake predation of hatchlings could be placing additional pressure on threatened populations of freshwater turtles in Australia, warranting further investigation.

The identity of Chelodina oblonga Gray 1841 (Testudines: Chelidae) reassessed.

The identity of Chelodina oblonga has been unclear because it has been variously defined to include populations of snake-necked chelid turtle from the southwest of Western Australia, across northern Australia, Cape York and southern New Guinea in its broadest conception, from just the northern part of this range (northern Australia and New Guinea), or restricted to the southwest corner of Western Australia in its narrowest conception. Uncertainty over the identity of the type specimens has added to the confusion. In this paper, we review the historical data on the extent of the type series of Chelodina oblonga, and its potential provenance, and find evidence that resolves some of the inconsistencies in previous literature on the identification of the type. Our analysis casts doubt on the northern Australian provenance of the type material. Hence, we return the name C. oblonga to the south-western species, in accordance with the genetic evidence for the provenance of the type in the Natural History Museum, London, and the external morphology of the type series. We designate a lectotype for the species, and redefine the subgeneric names that apply to the Australasian genus Chelodina, providing a new subgeneric name for one lineage.

Land use surrounding wetlands influences urban populations of a freshwater turtle

Abstract Urbanization is one of the most influential land use changes globally and continues to affect wetland ecosystems and their biota. Freshwater turtles, which rely on both terrestrial and aquatic habitats to complete their life cycles, are one of the most endangered vertebrate groups, with approximately 60% of species threatened. Although habitat alteration caused by urbanization is recognized as one of the main threats to freshwater turtles, there is a paucity of studies quantifying the effects of terrestrial habitat change on turtle populations. The aim of this study was to determine how terrestrial land use change, associated with urbanization, influences the viability of freshwater turtle populations. Thirty‐three wetlands were sampled for the southwestern snake‐necked turtle (Chelodina colliei Gray, 1856) (Chelidae) between October 2016 and February 2017 within a region of continuing urban intensification. Land use and habitat types were classified at the aquatic–terrestrial interface and within a 300‐m band around each wetland. Generalized linear mixed models were used to identify the land use variables that best explained the relative abundance of C. colliei. Turtle abundance and population structure varied widely among wetlands. The percentage of residential land use, and the presence and accessibility of fringing native vegetation, was positively associated with the relative abundance of C. colliei. The association with residential land use may be an artefact of historical land use, whereas the association with native vegetation is probably because adjacent vegetation provides connectivity with suitable nesting sites, and thus facilitates increased recruitment. This study shows how the modification of terrestrial habitat around wetlands may directly influence the population viability of freshwater turtles. Protection and restoration of native vegetation fringing urban wetlands is crucial to support the viability of remnant freshwater turtle populations.

Hepatic CT attenuation differs in three species of freshwater turtles and hepatic Hounsfield units increase with folliculogenesis in wild Blanding's turtles (Emydoidea blandingii).

Freshwater turtle species are suffering from anthropocentric-caused population declines, making preservation of professionally managed populations increasingly important. Turtles under professional care have an increased risk to develop hepatic lipidosis, potentially resulting in early death. Computed tomography can provide an antemortem screening for increased fatty liver composition. A goal of this prospective analytical cross-sectional study was to assess the hepatic attenuation measured as Hounsfield units (HU) in a wild population of a freshwater turtle species, and then compare hepatic HU to freshwater turtles under professional care. Ninety-five wild Blanding's turtles (BT; Emydoidea blandingii) as well as 10 Vietnamese Pond turtles (VPT; Mauremys annamensis) and six Northern Snake-Necked turtles (NSNT; Chelodina oblonga) under professional care underwent CT with quantification of hepatic HU. Hepatic HU were correlated to serum chemistry findings and the presence of follicles was recorded in BT. The mean (±SD) hepatic attenuation for 95 wild BT was 97.5 HU ±9.6. There were significant differences in hepatic attenuation among VPT, NSNT, and BT, with median HU values (range) of 5.39 HU (-6.45 to 61.50), 71.74 HU (59.44-94.49), and 95.43 HU (74.41-124.56), respectively. Aspartate aminotransferase (AST) values had a weak negative correlation to HU with a coefficient of -0.85 (P<.001). The hepatic attenuation was significantly higher for individuals undergoing folliculogenesis (P=.007). The decreased HU values were significantly negatively correlated with AST values. Findings supported the use of CT as an aid for guiding future management practices in freshwater turtles.

Working with land and sea rangers to tackle tropical wetland restoration and conservation on the north-western islands, Torres Straits, Australia

Importance of community stakeholder participation in coastal freshwater and tidal wetland monitoring and restoration has become increasingly recognised. In Australia, Land and Sea Rangers (LSR) are appointed land and sea custodians from local indigenous communities and under guidance of experts learn a range of scientifically relevant and rigorous sampling techniques to protect and conserve Country. Scientific training to build LSR confidence to tackle restoration and conservation of sensitive and culturally important wetlands is shown here. Between May 2014 and May 2015 three training campaigns were completed where LSR on Boigu and Saibai Islands (the most northern islands in the Torres Straits, Australia), completed water quality and wetland flora/fauna surveys across both islands. Forty wetland fauna species were documented (with a similar wetland assemblage on each ANOSIM P > 0.4) comprising 35 fish species (including the invasive freshwater climbing perch, Anabas testudineus), two crustaceans, a freshwater turtle (Chelodina oblonga) (a relic freshwater species after the last sea level rise approximately 6,000 years ago in the region), and two mangrove snakes (Myron richardsoni and Fordonia leucobalia) (both snake records represent a range extension). This data was presented at community workshops with the purpose to build LSR confidence, and with the community, develop a plan to conserve wetland cultural and environmental values. Five thematic wetland conservation themes were identified which resulted in agreeing to management actions necessary on both islands. Since the inception of this program in 2014, additional LSR restoration and monitoring programs have extended to wetlands on other islands in the Torres Straits. We advocate the need for more remote area wetland monitoring and management programs facilitated through LSR programs.

Resource partitioning among five sympatric species of freshwater turtles from the wet–dry tropics of northern Australia

Context Resource partitioning of diet and microhabitat was examined for five sympatric species of freshwater turtles in the Daly River in the northern end of Northern Territory (Top End) in Australia. The Daly River supports a high diversity of freshwater turtles, making it the ideal place to study a freshwater turtle community. Aims To determine the dry-season diet and microhabitat use of Carettochelys insculpta, Elseya dentata, Chelodina oblonga, Emydura victoriae and Emydura subglobosa worrelli and examine intraspecific and interspecific niche overlap and ontogenetic dietary shift. Methods Gut contents were collected by stomach flushing, and microhabitat use was determined by recording where each turtle was first seen before capture. Diet and microhabitat use were compared using an index of relative importance. Niche overlap was measured with Horn’s overlap index. Key results Carettochelys insculpta is an opportunistic omnivore that feeds mostly on ribbonweed (Vallisneria spiralis) and aquatic snails. Elseya dentata is herbivorous, feeding primarily on aquatic algae. The diets of C. insculpta and E. dentata overlapped moderately, but the overall niche overlap was low because they occupied different microhabitats within the river. Chelodina oblonga fed very little, and may use the Daly River as a dry-season refuge. Emydura victoriae is molluscivorous, consuming more molluscs as it grows. This ontogenetic dietary shift was associated with megacephaly (extreme broadly expanded head that is too large to fit into the carapace) and expanded triturating surfaces. This specialisation allows adult E. victoriae to feed exclusively on molluscs and so their diet overlapped little with other species. Emydura subglobosa worrelli was omnivorous, consuming mostly freshwater sponge and apparently preferring more lentic water. Conclusions The freshwater turtles of the wet–dry tropics are usually reported as being heavily reliant on the seeds, fruits and leaves of riparian vegetation; however, the present study showed that the dry-season diet in perennial rivers is primarily of aquatic origin. Implications The study suggested that populations of C. insculpta, E. dentata and E. victoriae could be threatened by broad-scale development in northern Australia if there were substantive impacts on aquatic macrophytes and molluscs in the Daly River system.

How to catch red foxes red handed: identifying predation of freshwater turtles and nests

Context Predation is one of the key contributors to mortality in freshwater turtles. Confirming the identity of predators is an important step towards conservation management action. Throughout Australia, the red fox (Vulpes vulpes) is suspected to apply significant and unsustainable predation pressure to turtle populations, killing adults and depredating nests; however methods for confirming this are limited. Aims The present study used a range of methods to confirm predation of oblong turtle (Chelodina colliei) nests and adults by the introduced red fox. Methods First, depredated adult carapaces, and turtle egg-shell fragments from excavated nests were swabbed and analysed for trace DNA. Second, we used artificial turtle nests, monitored by camera traps, to analyse seasonal changes in the behaviour of foxes around sites where turtle nests are present, including over the nesting season. Last, we used scat analysis to identify the prevalence of turtle remains in fox diet. Key results Predominantly fox DNA was recovered from both adult carapaces and depredated eggs. In addition, camera traps recorded only foxes depredating artificial nests. Despite this evidence that foxes kill adults and excavated nests, we found that turtle remains were only a small part of the diet of foxes at this study site (hatchling or turtle egg shell were present in only 4% of 230 scats sampled). The diet of these foxes was largely anthropogenic-sourced foods, such as fruit (e.g. figs, grapes, melons; 81% of scats), sheep carrion (41%) and rodents (36%). Conclusions We conclude that DNA analysis, camera trapping and scat analysis are effective methods of identifying foxes as predators of adult turtle, and their nests. Furthermore, we found that anthropogenic foods (orchard crops, livestock or synanthropic species) may subsidise greater fox population size than might occur in their absence, thereby increasing potential pressure on these freshwater turtles. Implications Our findings give credence to the argument that foxes are effective predators of turtle adults and nests. In addition, the high proportion of anthropogenic food sources in the diet of foxes, and potential subsidisation, is an important consideration for land managers.

Underwater Hearing in Turtles.

The hearing of turtles is poorly understood compared with the other reptiles. Although the mechanism of transduction of sound into a neural signal via hair cells has been described in detail, the rest of the auditory system is largely a black box. What is known is that turtles have higher hearing thresholds than other reptiles, with best frequencies around 500 Hz. They also have lower underwater hearing thresholds than those in air, owing to resonance of the middle ear cavity. Further studies demonstrated that all families of turtles and tortoises share a common middle ear cavity morphology, with scaling best suited to underwater hearing. This supports an aquatic origin of the group. Because turtles hear best under water, it is important to examine their vulnerability to anthropogenic noise. However, the lack of basic data makes such experiments difficult because only a few species of turtles have published audiograms. There are also almost no behavioral data available (understandable due to training difficulties). Finally, few studies show what kinds of sounds are behaviorally relevant. One notable paper revealed that the Australian snake-necked turtle (Chelodina oblonga) has a vocal repertoire in air, at the interface, and under water. Findings like these suggest that there is more to the turtle aquatic auditory scene than previously thought.

Eimeria collieie n. sp. (Apicomplexa:Eimeriidae) from the western long-necked turtle (Chelodina colliei)

A new species, Eimeria collieie n. sp., is described from the western long-necked turtle (Chelodina colliei). Sporulated oocysts (n = 35) are spherical to subspherical, with colourless single layer oocyst wall, 0.6 ± 0.2 (0.4–0.7) µm thick. Oocyst with elongated ellipsoid sporocysts. Oocyst length, 29.8 ± 0.4 (28.2–31.0) µm; oocyst width, 29.4 ± 0.3 (28.0–30.8) µm; oocyst length/width (L/W) ratio, 1.0 ± 0.03 (1.0–1.05). Micropyle, oocyst residuum and polar granule were absent. Sporocysts with sporocyst residuum and 2 sporozoites. Sporocyst length, 21.6 ± 0.4 (21.2–22.0) µm; sporocyst width, 6.0 ± 0.3 (5.7–6.3) µm; sporocyst L/W ratio, 3.6 ± 0.2 (3.4–3.8). Stieda, parastieda and substieda bodies were absent. Sporozoite length, 14.0 ± 0.2 (13.8–14.2) µm; sporozoite width, 2.6 ± 0.2 (2.4–2.8) µm; sporozoite L/W ratio, 5.46 ± 0.10 (5.4–5.6). Molecular analysis was conducted at three loci: the 18S and 28S ribosomal RNA (rRNA), and the mitochondrial cytochrome oxidase gene (COI). At the 18S rRNA locus, E. collieie n. sp. shared 96.4% and 98.3% genetic similarity to E. ranae (GenBank accession number: EU717219) and E. arnyi (AY613853) respectively. At the 28S rRNA locus, E. collieie n. sp. shared 91.6% genetic similarity to E. papillata (GenBank accession number: GU593706) and phylogenetic analysis at this locus placed E. collieie n. sp. in aseparateclade. At the COI locus, E. collieie n. sp. shared 92.7% genetic similarity to Eimeria setonicis (GenBankaccession number: KF225638) from a quokka (Setonix brachyurus) in Western Australia. Reptile-derived sequences were not available for the 28S rRNA and the COI loci. Based on morphological and molecular data, this isolate is a new species of coccidian parasite that, to date, has only been found in western long-necked turtles.

Turtle Watch: Community engagement and action

AbstractMany threats face the freshwater turtle, Chelodina colliei, also known as the oblong turtle. A community education project, Turtle Watch, focused on this target species and enabled effective conservation action to be implemented. Turtle Watch was conducted in the Perth Metropolitan Area of Western Australia, as the oblong turtle inhabits the wetlands of Perth. Predation, habitat loss, road deaths and climate change are key threats to this species. Nest predation issues arose during stage 1 of Turtle Watch (2005–2008), so Turtle Watch 2 (2010–2012) aimed to identify predators and foster community partnerships, including citizen science, to promote awareness and conservation of turtles. Turtle Watch 2 focused on four eco education centres and involved collaboration between government and community groups concerned about turtles. Camera surveillance was undertaken to determine predators. Various strategies were also adopted to promote community education and participation, such as, public talks, fair...

Reproductive investment compromises maternal health in three species of freshwater turtle.

Life-history theory predicts that a trade-off in the allocation of resources between different physiological systems exists because resources are finite. As a result, females investing heavily in reproduction may compromise their future health. We used hematology, serum biochemistry, mass, and morphometric measurements as indicators of physiological health state to investigate whether reproductive investment altered subsequent maternal health in three Australian freshwater turtles: the oblong turtle (Chelodina oblonga; n = 12), the Macquarie turtle (Emydura macquarii; n = 9), and the eastern long-necked turtle (Chelodina longicollis; n = 8). Maternal health was impaired in turtles that produced larger and heavier eggs and clutches. In C. oblonga and E. macquarii, increased reproductive investment generally resulted in negative changes to the hematology and serum biochemistry profile of maternal blood. Generally, increases in heterophil/lymphocyte ratio, aspartate transaminase, creatine kinase, calcium/phosphorus ratio, and albumin/globulin ratio were observed following reproduction, in addition to a decrease in glucose and total protein. These findings agree with the physiological constraint hypothesis and highlight the connection between life-history evolution and animal physiology by documenting, for the first time, how measures of physiological health state relate to reproductive investment in Australian freshwater turtles. Additionally, our findings suggest that body condition, a readily used morphological biomarker, is a poor predictor of health in turtles. Our results emphasize the need to investigate how maternal health is influenced by the reproductive process in different species.

The influence of temperature on embryonic developmental arrest in marine and freshwater turtles

Temporary arrest of embryonic development can occur both pre- and post-oviposition in turtles. Pre-ovipositional arrest is an obligate part of the life cycle and occurs universally in turtle embryos, commencing while eggs are in the oviduct and persisting until after oviposition. Pre-ovipositional arrest allows turtle mothers the flexibility to choose an optimum time to nest and provides embryos some capacity to respond to varying environmental conditions immediately after eggs are laid. Following oviposition, turtle embryos are known to be significantly affected by incubation conditions and specifically, temperature has a profound influence on developmental rate and success of embryos. We conducted a comparative investigation of how temperature influences (1) the duration of pre-ovipositional arrest after eggs are laid, (2) the number of embryos that fail to recommence development and (3) hatching success, using eggs of the green sea turtle (Chelonia mydas), and three species of freshwater turtle; the western oblong turtle (Chelodina oblonga), the eastern longneck turtle (Chelodina longicollis), and the Murray River turtle (Emydura macquarii). We incubated arrested eggs of each species at three different temperatures (low, medium, high) and monitored embryonic development immediately after oviposition and throughout incubation. Interspecific variation was evident in the effects that temperature had on pre-ovipositional arrest, subsequent embryonic development and hatching success. A major finding of this study was that, with the exception of E. macquarii, there was no significant difference in the time to white spot development (the first external visible sign of embryological development following arrest) between temperature treatments, suggesting that the resumption of development and the breaking of pre-ovipositional arrest after eggs are laid are independent of temperature. Furthermore, although the number of C. mydas eggs to successfully recommence development after oviposition was consistently high (~97–100%) across the three temperature treatments, a significant proportion of C. oblonga and E. macquarii eggs failed to resume development. In both the low and high temperature treatments the rate of C. oblonga embryo mortality was 95% and 60%, respectively, and for E. macquarii it was 53% and 24% respectively. These findings bring us a step closer to understanding why failure to recommence development after oviposition causes high rates of early stage embryo mortality and decreased hatching success in turtles.

HEMATOLOGIC AND SERUM BIOCHEMICAL VALUES OF GRAVID FRESHWATER AUSTRALIAN CHELONIANS

Hematologic and serum biochemical analyses were performed on 30 wild-caught, gravid, Australian freshwater chelonians. Species sampled were western long-necked turtles (Chelodina oblonga; n = 13), common long-necked turtles (Chelodina longicollis; n = 8), and Murray River turtles (Emydura macquarii; n = 9). Turtles were obtained from Lake Goolellal in Perth, Western Australia (C. oblonga), and Lake Coranderrk in Healesville, Victoria (C. longicollis and E. macquarii). All turtles were considered healthy at the time of sample collection. Blood results were similar to those reported in other freshwater chelonians, with the exception of elevated calcium levels in all species. Hypercalcemia was attributed to egg development and maturation. A hemoparasite morphologically resembling Haemogregarina clelandi was found in all C. oblonga samples and in four C. longicollis samples. Infection with H. clelandi appeared to have no physiological effects on blood parameters or morphometrics of infected turtles. Blood parameters were also considered poor indicators of female chelonian morphometrics and fecundity.

Aptorchis kuchlingi n. sp. (Digenea: Plagiorchioidea) from the Oblong Turtle, Chelodina oblonga (Pleurodira: Chelidae), in Western Australia

Aptorchis kuchlingi n. sp. is described from the rectum of the oblong turtle, Chelodina oblonga (Pleurodira: Chelidae), in southwest Western Australia. This digenean is morphologically most similar to Aptorchis pearsoni but can be differentiated from the latter species by: a relatively longer cirrus sac in relation to overall body length, a cirrus sac that reaches the ovary, testes that are situated much closer to the cirrus sac and separated from it only by the seminal receptacle, vitellarium that extends anteriorly beyond the ventral sucker, a relatively wider ventral sucker in relation to oral sucker width, and a pharynx equal in size or larger than the oral sucker. Comparison of approximately 2,400 bases of ribosomal DNA (complete internal transcribed spacer (ITS)1 + 5.8S + ITS2, partial 28S) obtained from all 5 known Aptorchis species also suggests a close relationship of the new species with A. pearsoni and strongly supports the status of A. kuchlingi n. sp. as a new species. This is the fourth species of Aptorchis reported from long-necked turtles (Chelodina) and the first species of the genus reported in C. oblonga.

Is sexual body shape dimorphism consistent in aquatic and terrestrial chelonians?

Comparisons between aquatic and terrestrial species provide an opportunity to examine how sex-specific adaptations interact with the environment to influence body shape. In terrestrial female tortoises, selection for fecundity favors the development of a large internal abdominal cavity to accommodate the clutch; in conspecific males, sexual selection favors mobility with large openings in the shell. To examine to what extent such trends apply in aquatic chelonians we compared the body shape of males and females of two aquatic turtles ( Chelodina colliei and Mauremys leprosa). In both species, females were larger than males. When controlled for body size, females exhibited a greater relative internal volume and a higher body condition index than males; both traits potentially correlate positively with fecundity. Males were more streamlined (hydrodynamic), and exhibited larger openings in the shell providing more space to move their longer limbs; such traits probably improve mobility and copulation ability (the males chase and grab the female for copulation). Overall, although the specific constraints imposed by terrestrial and aquatic locomotion shape the morphology of chelonians differently (aquatic turtles were flatter, hence more hydrodynamic than terrestrial tortoises), the direction for sexual shape dimorphism remained unaffected. Our main conclusion is that the direction of sexual shape dimorphism is probably more consistent than sexual size dimorphism in the animal kingdom.