Michael E. Seidel

Terrestrial dormancy in the turtle Kinosternon flavescens: Respiratory metabolism and dehydration

Experimentally induced terrestrial dormancy resulted in reduced rates of oxygen consumption and carbon dioxide release by the turtle, Kinosternon flavescens. 1. 2. An unusually low respiratory quotient for dormant turtles indicates retention of carbon dioxide. 2. 3. Sharply elevated levels of oxygen consumption upon emergence from dormancy suggest payment of an oxygen debt and support previous suspicion of increased anaerobic metabolism. 3. 4. Most of the weight lost by dormant turtles is attributed to dehydration rather than metabolism. 4. 5. Suppressed gas exchange apparently reduces water loss from the respiratory tract, an adjustment which may be essential in avoiding severe dehydration.

Biochemical comparisons and phylogenetic relationships in the family Kinosternidae (Testudines)

Electrophoretic relationships among 18 species, representing all four genera of kinosternid turtles, were defined by phenetic and cladistic analyses. Relatively little protein variation was observed among most species of Kinosternon from Mexico and Central America, except K. sonoriense and K. leucostomum. K. bauri and K. subrubrum, which inhabit the eastern United States, do not appear to be sister taxa to other Kinosternon species. Biochemical results, supported by previous karyotypic data, indicate that K. bauri and K. subrubrum are more closely allied to Sternotherus than to congeners; and that Kinosternon is a paraphyletic taxon. Electromorphic data support the thesis that Kinosterninae is a monophyletic subfamily divergent from Claudius and Staurotypus. T HE New World family Kinosternidae (Gray) is an assemblage of four genera: Claudius Cope and Staurotypus Wagler in the subfamily Staurotypinae and Sternotherus Gray and Kinosternon Spix in the Kinosterninae. The two species of Staurotypus (S. salvini, S. triporcatus) and the monotypic Claudius angustatus are highly aquatic inhabitants of Mexico and northern Central America. Sternotherus contains four aquatic species (S. carinatus, S. depressus, S. minor, S. odoratus) distributed over eastern United States. The highly polytypic genus Kinosternon is partitioned into 15 species (K. acutum, K. alamosae, K. angustipons, K. bauri, K. creaseri, K. dunni, K. flavescens, K. herrerai, K. hirtipes, K. integrum, K. leucostomum, K. oaxacae, K. scorpioides, K. sonoriense, K. subrubrum), which inhabit a variety of mesic to xeric environments from central South America throughout most of Central America and the United States. Two Kinosternon species (K. bauri and K. subrubrum) inhabit eastern United States in broad sympatry with Sternotherus and at least three species (K. scorpioides, K. leucostomum and K. acutum) are sympatric with the staurotypines in Mexico, Belize and Guatemala.

Salinity Tolerance of Estuarine and Insular Emydid Turtles (Pseudemys nelsoni and Trachemys decussata)

ABSTRAcr. - Pseudemys nelsoni and Trachemys decussata inhabit brackish water in mainland areas of extreme southern Florida and on Grand Cayman Island. They appear to be intermediate in their salinity tolerance between truly freshwater forms and the highly specialized estuarine terrapin (Malaclemys). Unfed P. nelsoni (730-1240 g) had especially low rates of mass loss (primarily net water loss) in 100% sea water (about 0.4% initial mass/day). Smaller T. decussata (200-240 g) had higher values (about 0.8% /day), yet these rates were still lower than four values obtained on typical freshwater species (1.8-7.6% /day) held in 100% sea water. Mean whole body water effluxes in 100% sea water of adult P. nelsoni and T. decussata larger than 60 g were low (0.24-0.47 ml/100 g-h). Hatchling T. decussata had much higher rates of water efflux (1.0 ml/100 g-h). Sodium effluxes in 100% sea water were low (less than 100 umol/100 g-h) in all size classes. There was no stimulation in sodium efflux after salt loading in P. nelsoni, nor in T. decussata after dehydration in saline solutions. This implies the lack of salt glands in these species. Sodium influx in 100% sea water was very low in adult P. nelsoni and in T. decussata larger than 200 g. There was a progressive increase in sodium influx with declining size in T. decussata, so that hatchlings underwent a considerable net uptake of sodium in sea water. Hatchling T. decussata fed fish ad libitum were unable to maintain mass or grow when the salinity exceeded 41% sea water. Juveniles of about 80 g grew at salinities up to 59% sea water, representing a significant increase in tolerance above that of the hatchlings. Additionally, 80 g turtles grew significantly faster in 25% sea water than in fresh water. Large individuals (>200 g) of both species tolerated immersion in 100% sea water for prolonged periods (at least 10-24 days). Their natural habitats vary seasonally in salinity, but remain on average quite dilute due to rainfall.

Aspects of evaporative water loss in the mud turtles kinosternon hirtipes and Kinosternon flavescens

Abstract 1. 1. Kinosternon hirtipes, a primarily aquatic turtle, consistently demonstrates greater rates of evaporative water loss (EWL) compared to the more terrestrial congener K. flaivscens . 2. 2. Quantitative serum chemistry analysis indicates that 12-day experimental dehydration does not produce extreme physiological stress in either species. 3. 3. Measurements of oxygen consumption and carton dioxide release suggest that interspecific variations in EWL are not attributable to respiratory w rer loss or metabolism. 4. 4. General morphology and moderate-sized plastrons of K. hirtipes and K. flavescens suggest similar functional evaporative surface areas for these species. 5. 5. Following dehydration, both species show increased thickening of the horny epidermal layer of integument. Interspecific variations in the degree of keratinization may account for the superior ability of K. flavescens to resist cutaneous water loss.

Variation in turtle myoglobins (subfamily emydinae: Testudines) examined by isoelectric focusing

Abstract 1. 1. Myoglobins from heart and skeletal muscle of turtles were analyzed by thin-layer isoelectric focusing. 2. 2. Within the subfamily Emydinae, variation in the occurrence of two myoglobin electromorphs (pI 6.8 and 6.9) was detected. 3. 3. Patterns of myoglobin polymorphism support dividing the Emydinae into two subfamilies and help resolve controversial theories on relationships of the genus Deirochelys . 4. 4. Possible adaptive significance of the myoglobin variants (isoforms) remains to be determined.

Status of the Trachemyd Turtles (Testudines: Emydidae) on Hispaniola

The taxonomy and distribution of Trachemys decorata (Barbour and Carr) and Tra- chemys stejnegeri vicina (Barbour and Carr) from Haiti and Republica Dominicana are discussed. External morphology is examined by multivariate and univariate statistics. Two morphotypes are reported, supporting continued recognition of two taxa which are distinguished by head and shell markings, coloration, and scute measurements. Addition of localities and reappraisal of old records indicate that the two forms of Trachemys on Hispaniola are entirely allopatric.

Morphological Homogeneity in the Turtle Sternotherus odoratus (Kinosternidae) Throughout its Range

Multivariate discriminant analysis of 19 morphological characters in S. odoratus re- vealed substantial intrapopulational variation but relatively little divergence among populations throughout the range. Results showed populations group extensively as overlapping clusters for each sex, and a general congruence between phenetic and geographic distances. Possible explana- tions for morphological similarity among populations are gene flow due to aquatic dispersal, stream capture or overland movement, and similarity of selective regimes throughout the range. The stinkpot, Sternotherus odoratus, is a small aquatic turtle in the family Kino- sternidae. Of the four recognized species of the genus, S. odoratus has the widest distribution (Conant, 1975), which in- cludes the eastern and central United

Respiratory metabolism of temperate and tropical American turtles (Genus Chrysemys)

Abstract 1. 1. Comparison of oxygen consumption by Chrysemys picta, Chrysemys scripta ornata and Chrysemys scripta taylori showed evidence of adaptation to climate. 2. 2. The temperate turtle, C. picta , did not demonstrate a difference between metabolic rates tested at 12°C ambient temperature and rates tested at 25°C. 3. 3. C. scripta taylori , endemic to warm waters, had a significantly lower mean oxygen consumption at 12 than at 25°C.

Hemoglobin Variation and Comments on Systematic Relationships in the Turtle Family Emydidae

Abstract Hemoglobin polymorphism in all 10 genera of emydid turtles was examined by isoelectric focusing. Two major (highly concentrated) forms of hemoglobin were revealed in all turtles examined. Cathodal electromorphic bands of hemoglobin (Hb A) demonstrated isoelectric points (pI) 7.6–8.3, and anodal bands (Hb D) demonstrated isoelectric points 5.2–6.1. The most common forms of Hb A (pI 8.3) and Hb D (pI 6.0) were shared by Pseudemys, Graptemys, Malaclemys, and Trachemys. Relatively little intrageneric variation was observed except among species of Clemmys, which lends support to the hypothesis that the genus Clemmys is not monophyletic. Ontogenetic hemoglobin polymorphism was observed in Trachemys scripta elegans and Trachemys scripta troostii.