Kinixys Erosa Research Articles

Cover Image

African Journal of EcologyVolume 61, Issue 1 p. i-i COVER IMAGEFree Access Cover Image First published: 18 February 2023 https://doi.org/10.1111/aje.12930AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Graphical Abstract Cover caption: A threatened forest tortoise of African rainforests, Kinixys erosa. (Photo: Luca Luiselli). Volume61, Issue1March 2023Pages i-i RelatedInformation

Life history and age-dependent mortality processes in tropical reptiles

AbstractActuarial senescence appears to be a common process, and senescence patterns are highly variable across the tree of life. To date, studies on animal senescence have largely focused on model species, such as as fruit flies, humans and a few other endotherms. In contrast, our knowledge about ageing remains fragmentary in ectotherm vertebrates, such as reptiles. Here, we examined life history and age-dependent mortality patterns in three tropical tortoises (Kinixys erosa, Kinixys homeana and Kinixys nogueyi) and snakes (Bitis gabonica, Bitis nasicornis and Causus maculatus). Our study revealed that tortoises of the genus Kinixys had a higher survival and a lower recruitment than snakes of the genera Bitis and Causus, indicating a slower life history. Furthermore, we confirmed that survival decreased more slowly with age in tortoises than in snakes. In addition, we highlighted contrasting patterns of age-dependent mortality among the three genera. In Kinixys, the relationship between mortality rate and age was positive and linear, suggesting gradual senescence over tortoise lifetime. In contrast, the relationship between mortality rate and age was negative and sharp in Bitis and Causus, possibly owing to a ‘negative senescence’. Our study is one of the few to have examined and compared the demography and age-dependent mortality patterns of tropical reptiles. Among other things, our results suggest that although negative senescence has never been reported in endotherm vertebrates, it could be a common phenomenon in ectotherms.

Compressive deformation and failure of trabecular structures in a turtle shell

Turtle shells comprising of cortical and trabecular bones exhibit intriguing mechanical properties. In this work, compression tests were performed using specimens made from the carapace of Kinixys erosa turtle. A combination of imaging techniques and mechanical testing were employed to examine the responses of hierarchical microstructures of turtle shell under compression. Finite element models produced from microCT-scanned microstructures and analytical foam structure models were then used to elucidate local responses of trabecular bones deformed under compression. The results reveal the contributions from micro-strut bending and stress concentrations to the fractural mechanisms of trabecular bone structures. The porous structures of turtle shells could be an excellent prototype for the bioinspired design of deformation-resistant structures. Statement of SignificanceIn this study, a combination of analytical, computational models and experiments is used to study the underlying mechanisms that contribute to the compressive deformation of a Kinixys erosa turtle shell between the nano-, micro- and macro-scales. The proposed work shows that the turtle shell structures can be analyzed as sandwich structures that have the capacity to concentrate deformation and stresses within the trabecular bones, which enables significant energy absorption during compressive deformation. Then, the trends in the deformation characteristics and the strengths of the trabecular bone segments are well predicted by the four-strut model, which captures the effects of variations in strut length, thickness and orientation that are related to microstructural uncertainties of the turtle shells. The above results also suggest that the model may be used to guide the bioinspired design of sandwich porous structures that mimic the properties of the cortical and trabecular bone segments of turtle shells under a range of loading conditions.

Wild chimpanzees (Pan troglodytes troglodytes) exploit tortoises (Kinixys erosa) via percussive technology

Chimpanzees (Pan troglodytes), one of humankinds’ closest living relatives, are known to hunt and consume the meat of various animal taxa. Although some researchers have presented indirect evidence that chimpanzees may also prey on tortoises, until now, direct observations of this behaviour did not exist. Here, we provide systematic descriptions of the first observations of chimpanzee predation on tortoises (Kinixys erosa). We made these unprecedented observations on newly habituated chimpanzees (Pan troglodytes troglodytes) of the Rekambo community, living in the Loango National Park, Gabon. The behaviour qualified as customary, that is occurring in most or all adult males, involved a distinct smashing technique, and resulted frequently in food sharing with other group members. Our observations shed new light on the hitherto little understood percussive technology of chimpanzees, and expand our current knowledge on chimpanzees’ dietary and predatory repertoires with respect to reptiles. We also report a case of food storage and discuss it in the context of future-oriented cognition. Our findings suggest the need for more nuanced interpretations of chimpanzees’ cognitive skills in combination with an in-depth understanding of their unique socio-ecological niches. They further emphasize the importance of nonhuman primate field observations to inform theories of hominin evolution.

Haemosporidian Parasites of Reptiles and Birds from Gabon, Central Africa.

Haemosporidian parasites are protozoans that infect many different vertebrate hosts. Re-examination of the diversity of haemosporidian parasites, using molecular tools, has generally led to rearrangements of traditional classifications. In this study, we explored the diversity of haemosporidian parasites infecting some species of reptile and birds living in the forests of Gabon, Central Africa, by analyzing a collection of 128 samples of reptiles and birds. We found that samples from 2 tortoise species (Pelusios castaneus and Kinixys erosa) and 3 bird species (Turtur afer, Ceratogymna atrata, and Agelastes niger) were infected by Haemocystidium spp. and Parahaemoproteus spp., respectively. From an ecological point of view, these lineages of parasites do not show host specificity because we have found them in several host species (2 tortoise and 3 bird species) that come from different areas of Gabon forest which are infected with these parasites. Also, our phylogenetic analyses revealed that the obtained lineages are related to isolates from other continents found in the same groups of vertebrates. Thus, our results show that haemosporidian parasites are also infecting central African vertebrates and that new lineages of these parasites are circulating in wild animals of the Gabon forest.

Bioinspired Design

Bioinspired design involves the use of concepts observed in natural biological materials in engineering design. The hope is that the leveraging of biological materials in the engineering domain can lead to many technological innovations and novel products. This work presents the initial material characterization of kinixys erosa tortoise shell using a combination of x-ray diffraction, optical/scanning electron microscopy and micro-mechanical testing. The results were used in the analytical/computational modelling of shell structures. The potential implications or the results were then discussed to give fundamental understanding of deformation and stress responses of shell structures

Turtles and Tortoises of Togo: Historical Data, Distribution, Ecology, and Conservation

The chelonian fauna of Togo (West Africa) has been scarcely studied to date. In this article, we review and summarize all available data on the distribution, ecology, and conservation status of the chelonian species of Togo and present a short historical perspective on the development of studies on these reptiles. Overall, 13 chelonian species are found in Togo, 4 being marine, 3 terrestrial, and 6 freshwater. Among the marine species, only 2 of them nest on Togolese beaches (Lepidochelys olivacea and Dermochelys coriacea). Two species (Chelonia mydas and L. olivacea) are still locally common. Concerning the terrestrial and freshwater species, they differed remarkably in terms of their distribution by ecological zone. Cluster analyses revealed the existence of 3 clusters of species, 1 that contains the “forest” species, 1 accommodating the Sudanese savannah species, and a third cluster for the generalist savannah species. The conservation status of the various species and their dissimilarities in terms of threat score categories were assessed through a multivariate model following published work on African chelonian species in general. The results of this model indicate that the potentially most threatened species in Togo are Kinixys erosa, Kinixys homeana, and the 2 Cyclanorbis species (C. senegalensis and C. elegans), with Trionyx triunguis also being possibly seriously threatened. Overall, using the International Union for Conservation of Nature Red List criteria, the concurrent presence of 2 Critically Endangered (K. homeana, C. elegans), 1 Endangered (K. erosa), and several Vulnerable species shows that the chelonian fauna of Togo should be of priority relevance for the competent international agencies.

Unsustainable Exploitation of Freshwater Wetland Turtles and Tortoises in Central Niger Delta

Wildlife is commonly exploited as sources of animal protein in Nigeria. This study was designed to assess the rate of wildlife exploitation in 2 communities in Delta State, Nigeria specialized in the sale of turtles and tortoises. These two communities receive 1,512 turtles and tortoises weekly from hunters and display them for sales along the East-West Road. Fortnightly field surveys in these communities show that 12 shops displayed 144 – 212 numbers of turtles and tortoises while the rest are kept in bulk storage. Each shop sells 16 – 20 (average 18) on favorable business days and 3 – 9 (average 6) on unfavorable days. The retailer makes an average profit of N1000, N 3,500 and N 4000 per unit of small, medium and large species respectively (US $1 = N 156). The numbers of retailers are increasing. The turtles and tortoises were captured from freshwater wetlands located in an island bounded in the north by the bifurcation of River Niger at Aboh, and between Ramos River to the west and San Bartholomew River to the east and in the south by the mangrove ecosystem at the fringe of the Atlantic Ocean. These wetlands turtles and tortoises are mostly exploited for meat, traditional medicine and as source of employment and income. The species exploited include 2 species of turtles (Pelusios niger and P. castaneus) and tortoises (Kinixys erosa and K. homeana). The study concluded that this pattern of wildlife exploitation is unsustainable.

Changes in the haematological profile of the West African hinge-backed Tortoise (Kinixys erosa) anaesthetized with ether or thiopentone sodium

The effect of ether or thiopentone sodium on haematological parameters of tortoise was determined by evaluating the Packed Cell Volume (PCV), Red Blood Cell (RBC) count, Haemoglobin (Hb) concentration, Mean Corpuscular Haemoglobin Concentration (MCHC), Mean Corpuscular Volume (MCV), Mean Corpuscular Haemoglobin (MCH) and White Blood Cell (WBC) count of ether or thiopentone-anaesthetized West African Hinge-Backed Tortoise (Kinixys erosa). The blood clotting and sleeping time were also determined. Fifteen tortoises were randomly but equally divided into three groups. Tortoises in Group I were administered with 0.9% Physiological saline, while tortoises in Group II and III were administered with ether and thiopentone sodium respectively. Ether was administered by inhalation while thiopentone sodium was administered intramuscularly. The sleeping time was significantly longer for ether than for thiopentone sodium. The difference in the sleeping time is ascribed to the differences in the physicochemical, pharmacokinetic or pharmacodynamic properties of the two anaesthetics. Blood clotting was delayed in tortoises anaesthetized with ether compared with thiopentone-anaesthetized tortoises, which makes thiopentone a more reliable anaesthetic agent for invasive surgical procedures in the tortoise than ether. The two anaesthetics elicited depression of the haematological parameters of the tortoises with significant (P<0.05) decreases in the PCV and RBC values. Hb concentration and MCV were significantly decreased for ether-anaesthetized tortoises, while MCH was significantly decreased for thiopentone-anaesthetized tortoises. The WBC count was elevated in ether-administered tortoises while the value decreased in thiopentone-administered tortoises. The elevation of WBC count was attributed to the irritant effect of ether. It was concluded that ether or thiopentone caused depression of haematological parameters in West African Hinge-Backed tortoise which should be taken into consideration when interpreting values of blood parameters obtained from anaesthetized subjects. Key words: Ether, thiopentone sodium, haematology, sleeping time, West African hinge-backed tortoise.

The purification and some properties of rhodanese from tortoise (Kinixys erosa, Schweigger) liver

Rhodanese (cyanide: thiosulphate sulphur transferase; EC.2.8.1.1) was isolated from cytosolic fraction of tortoise liver using ammonium sulphate fractionation, ion exchange chromatography and gel filtration from the liver of tortoise. The enzyme had a specific activity of 14.43 RU per milligram of protein. The Km values for KCN and Na2S2O3 were 16 mM and 30.0 mM respectively. The native and subunit molecular weight of the enzyme was found to be 33,000 and 35,000 dalton respectively. The optimum pH andtemperature for the enzyme activity were 6.5 and 50 °C respectively. The enzyme was inhibited by Ba2+ and Zn2+ but not affected by Mn2+, Co2+, Sn2+, Ni2+ and NH4 2+.© 2009 International Formulae Group. All rights reserved.Keywords: Rhodanese, tortoise, detoxification, sulphurtransferase enzyme, cyanide toxicity.

TWO NEW HETERAKID (NEMATODA) SPECIES FROM KINIXYS EROSA (SCHWEIGGER, 1812), (CHELONII: TESTUDINIDAE) IN THE DEMOCRATIC REPUBLIC OF CONGO

Two species of Africana Tavassos, 1920 (Africana kinixysae n. sp. and Africana congoensis n. sp.) are described from Kinixys erosa (Schweigger, 1812) in the Democratic Republic of Congo. Light microscopy and scanning electron microscopy studies revealed morphological differences in the structure of the male caudal end and cephalic end, which helped to differentiate these new species from the other species of the genus, and from each other. A key for determination of all species in the genus is provided.

Food niche overlap between sympatric potential competitors increases with habitat alteration at different trophic levels in rain-forest reptiles (omnivorous tortoises and carnivorous vipers)

Comparisons of sympatric reptile species were used to assess the variation in niche overlap for food between potential competitors at different trophic levels. Omnivorous tortoises and carnivorous vipers inhabiting the rain-forest region of West Africa were used as study models. Food niche overlap between species increased with habitat alteration in both the independent study systems: tortoises (Kinixys homeana and Kinixys erosa) and vipers (Bitis gabonica and Bitis nasicornis) showed lower values of Pianka's niche overlap index in the pristine habitat than in the altered habitat, and these differences in overlap values did not depend on chance after Monte Carlo simulations. There were higher inter-habitat food niche overlaps within-species than between-species. Permutation tests (assessed after 5000 iterations) revealed that, for both study systems, the P-values became significantly smaller with fewer resource states, thus showing the niche overlap between species really increases after habitat alteration. The observed increases in food niche overlap between species accomplished with rain-forest habitat degradation in turn may be predicted to have cumulative effects on reducing the level of forest biodiversity.

Habitat Use, Home Range, and Activity Patterns of Hingeback Tortoises, Kinixys erosa and K. homeana, in Southwestern Cameroon

Home range, habitat use, and seasonal behavior of the Central African forest-dwelling hingeback tortoises Kinixys erosa and K. homeana were quantified by radio tracking 3 translocated and 6 resident individuals for up to 2.3 years in southwestern Cameroon where the two species are sympatric. Individuals of both species varied widely in total and seasonal minimum convex polygon home range estimates (1.1–47.8 ha). Harmonic surface area home range estimates, however, show that most of each tortoise's locations occurred within a relatively small core area representing 5%–25% of an individual's total range. Males of both species had the largest home ranges, and specimens tracked for more than one year showed a decrease in yearly home range size estimates. Considerable overlap of total home ranges but little overlap of core areas exist among individuals of species. Kinixys homeana was located more frequently in forest gaps than was K. erosa, but substantial overlap occurred of habitats and microhabitats used between species. Tortoises tended to gain weight at the beginning and end of the rainy season, and lost weight through the middle of each season.

Aspects of comparative thermal ecology of sympatric hinge‐back tortoises (Kinixys homeana and Kinixys erosa) in the Niger Delta, southern Nigeria

AbstractAspects of the thermal ecology of two sympatric hinge‐back tortoises, Kinixys erosa and Kinixys homeana, were studied in the rainforest zone of south‐eastern Nigeria (West Africa). There were no significant differences in mean body temperatures (Tb) among K. homeana males, K. homeana females, K. erosa males and K. erosa females. In both species, there was a significant correlation between Tb and air temperature (Ta), and the regression line of Ta plotted against Tb differed significantly from the line of ideal poikilothermy. These regressions did not differ significantly between sexes in either species. There were no significant differences in terms of mean Tb in K. homeana during the various day‐hour intervals, whereas the mean Tb of K. erosa varied significantly among the various daytime intervals, attaining the higher values at 11.01–15.00 and 15.01–19.00 hours. In both species, Tbs were nearly always below Tas, and the negative difference ‘Tb ‐ Ta’ increased with increasing Ta. The hourly‐time course of the difference between Tb and Ta showed significant differences in K. homeana (with the higher negative differences at 11.01–15.00 and 15.01–19.00 hours), whereas no such difference was observed in K. erosa. In general, tortoises of both species showed behavioural thermoregulation in their avoidance of overheating in tropical environments, taking advantage of shady forest environments.

Seasonal activity patterns and diet divergence of three sympatric Afrotropical tortoise species (genus Kinixys)

Three species of hinge-back tortoises (Kinixys belliana nogueyi, Kinixys erosa, Kinixys homeana) are found in simpatry in the rainforests of the Niger Delta, southern Nigeria (west Africa). The seasonal activity patterns and food habits of these tortoises are studied in the present paper. K. erosa and K. homeana have similar activity patterns, with peaks occurring during the wet season. Kinixys belliana was found only during the wet months. There was no evidence of any specific effect of humidity of the air on their activity intensity, and it seems likely that, more than absolute values of air humidity, the crucial factor to force tortoises into high activity is the sudden change between dry days and very wet days at the onset of the rainy season (end of March-early April). K. homeana was significantly more active in the early phase of the wet season. Common items, which were consumed by all three predator species, were: plant matters, fruits and berries, fungi, Oligochaeta, and Gastropoda Pulmonata, whereas Araneidae were also consumed by all species, but much more rarely. Common prey items, which were consumed by K. homeana and not by K. erosa were: Coleoptera larvae, Dermaptera, and termites. K. homeana appeared more generalist than K. erosa, and the respective diets diverged considerably both in dry and in wet seasons. On the other hand, the diets of K. erosa and K. belliana were more similar (at least in wet season).

Morphometrics and sexual dimorphism of the hinge‐back tortoises Kinixys erosa and Kinixys homeana (Reptilia: Testudinidae) in southwestern Cameroon

Morphometric data on a series of forest‐dwelling hingeback tortoises, 138 Kinixys erosa and 74 Kinixys homeana, from the Southwest Province of Cameroon, Africa, where they are sympatric, are presented. The two species exhibited opposite trends in sexual size dimorphism. Unique among Kinixys, male K. erosa are significantly larger than females. All but two comparisons of height on length, width on length, and width on height allometries between males, females, and juveniles of each species were significantly different. Females of both species were relatively taller than their male counterparts. The two species differed in height/width growth allometry at sexual maturity.

Two phosphoglycoproteins (phosvitins) from Kinixys erosa oocytes

1. 1. Two phosphoproteins have been isolated from maturing egg yolks of Kinixys erosa by a combination of gel filtration and anion exchange chromatography. 2. 2. The two proteins, TEYP-2 and TEYP-3, have M r s of 68,000 and 29,000, respectively. 3. 3. They have a phosphorus content of 5.5 and 30.0 μmol Pi/mg protein, respectively. 4. 4. Serine accounts for 45 and 16.5% of the amino acid residues. 5. 5. They are both glycoproteins and both have lysine as the N- terminal amino acid residue.

Purification and some properties of pyruvate kinase from the skeletal muscle of African land tortoise Kinixys erosa (Linn)

1. 1. Pyruvate kinase from Africa land tortoise ( Kinixys erosa) skeletal muscle was isolated and purified to homogeneity. 2. 2. The mol. wt of the enzyme was estimated to be 212,333 ± 2887 with four subunits of 49,680 ± 526. 3. 3. The enzyme, denatured by 4M guanidine-HCl, regained a maximum of 80–87% of its original activity upon dilution at 20°C and at a protein concentration of 80 μg/ml in appropriate buffer containing 10 mM PEP and 1 mM l-valine. The kinetics of renaturation was first order. 4. 4. The catalytically active renatured enzyme was a dimer even though it was kinetically similar to the tetrameric native enzyme.

New land tortoises (Testudines: Testudinidae) from the Miocene of Africa

The described fossil testudinids from the Miocene of Africa are reviewed. Geochelone stromeri sp. nov. is described from Lower Pliocene (Langebaanweg) and Miocene (Namib) specimens. Kinixys erosa, an extant species, is reported from Songhor Hill. Chersina sp. is reported from Arrisdrift. Impregnochelys pachytectis gen. et sp. nov. is described from Rusinga Island, Kenya, and is unique in having the anterior shell opening orientated ventrally and in having struts on the internal surface of the neurals, but shares with Kinixys a unique epiplastron shape, a high number of axillary scutes and unique orientation of the head of the femur.

On the quaternary structure ofKinixys erosa hemoglobins

Kinixys erosa hemoglobins TH1 and THII comigrate on SDS-PAGE with mol. wt of 18 kD. Consistent with their amino acid compositions, trypsinolysis of the succinylated molecules and hydrolysis of cyanylated THII yielded five and two fragments respectively.