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Using mtDNA sequence data and a phylogenetic approach, we examined the divergence and evolutionary history of the Toad-Headed Lizards of the Phrynocephalus versicolor species complex, which are currently assigned to three species, P. versicolor, Phrynocephalus frontalis, and Phrynocephalus przewalskii. Both parsimony and likelihood-based analyses resulted in three clades, which do not conform to the current species designation. The three species did not form mutually exclusive monophyletic groups. Instead, the populations from Tengger Desert, Ordos Highland, and further east, which include P. frontalis, P. przewalskii, and several populations of P. versicolor, formed a clade and we recommend recognizing them as a single species under the name P. przewalskii. The populations from the northwestern part of the complex's distribution also formed a monophyletic group, for which we recommend retaining the name P. versicolor. Finally, the southwestern populations share a unique evolutionary history and should be recognized as a new species, Phrynocephalus sp. The resulting phylogeny suggests that the species diversity and distribution patterns of P. przewalskii, P. versicolor, and Phrynocephalus sp. can be better explained by vicariance, rather than the traditional west-to-east dispersal hypothesis.
We mapped 112 restriction sites in the mitochondrial DNA genome of the Speckled Dace (Rhinichthys osculus), a small cyprinid fish broadly distributed in western North America. These data were used to derive a molecular phylogeny that was contrasted against the hydrographic evolution of the region. Although haplotypic variation was extensive among our 59 sampled populations and 104 individuals, their fidelity to current drainage basins was a hallmark of the study. Two large clades, representing the Colorado and Snake Rivers, were prominent in our results. The Colorado River clade was divided into four cohesive and well-defined subbasins that arose in profound isolation as an apparent response to regional aridity and tectonism. The Lower and Little Colorado River subbasins are sister to one another and (with the Upper Colorado River) form a large clade of higher-elevation populations that seemingly reflect postglacial recolonization from refugia in the Middle Colorado River. The latter subbasin is sister to the Los Angeles Basin and, thus, supports the hypothesis of an ancient connection between the two. A haplotype from the Northern Bonneville was sister to the entire Colorado River clade. The Snake River clade revealed a strongly supported Lahontan group that did not share haplotypes with surrounding basins. It contained instead scattered sites from former Pluvial Lake Lahontan, as well as from eastern California. It was, in turn, sister to the Owens River, whereas Rhinichthys falcatus was sister to this larger clade. The hypothesis of a southerly, “fishhook”-configured tributary associated with a westward-draining Pliocene Snake River was manifested by the relationship of this Lahontan clade to upper Snake and northern Bonneville localities. The Klamath/Pit and Columbia Rivers were sisters in a clade basal to all the above, which in turn supported the hypothesis of a pre-Pliocene western passage of the Snake River. Our data also suggested at least three separate ichthyofaunal invasions of California, as well as a Bonneville Basin fragmented by a north-south connection between southeastern Idaho and the Colorado River. The dual western and southern movements of R. osculus from southern Idaho argued for a northern origin, possibly associated with Tertiary Lake Idaho.
Atelopus is a species-rich genus of toads from the Neotropics. Many species of this genus are regarded as vulnerable or endangered because of apparent population declines. In most cases, reasons for declines remain unknown. Conservation efforts are needed, which require a profound knowledge of taxonomy. This paper contributes to the taxonomic status of Atelopus populations from the coastal mountain range of Venezuela. Atelopus cruciger is redescribed on the basis of the neotype and additional material from nine localities. Atelopus vogli here is considered a distinct species (not a junior synonym or subspecies of the former) known only from the type series and a few additional specimens collected at one single locality, which has been severely altered. The latter species lacks (whereas A. cruciger has) color pattern on the dorsum and is (in both sexes) smaller than A. cruciger. The two taxa also differ in hand morphology and characters of the sphenethmoid. Because of population declines in A. cruciger and the absence of recent records of A. vogli, in spite of intensive searches for both taxa, they should be considered as critically endangered. Comprehensive investigation evaluating the population status of both species is urgently recommended.
Male Oyster Toadfish Opsanus tau produce an advertisement call, the boatwhistle, using sexually dimorphic sonic muscles attached to the swimbladder. The fundamental frequency and duration of the boatwhistle change seasonally suggesting hormonal modulation of the output of pattern generators in the brain. The toadfish has an unusual protracted reproductive cycle in which testes contain mature sperm throughout the year, and females develop large eggs during late summer and fall for spawning the following spring although some may mate in the fall. This study quantified gonad development and plasma androgens in males and females throughout a seasonal cycle to relate them to the prolonged reproductive cycle and to quantitative changes in boatwhistle parameters. Median levels of testosterone (T) and 11- ketotestosterone (11KT) in males peak in May during the early part of the spawning season (461 pg/mL for T and 3746 for 11KT) and decline to 153 and 43 pg/mL, respectively, in June although spawning continues into July. A minor increase in gonosomatic index (GSI) and levels of both androgens (180 and 94 pg/mL, respectively) occurs in October. Median levels of T (328 pg/mL) and GSI in females also peak in May. In June, T levels drop in spawned females but remain elevated in those still gravid. Ovaries start to develop in late summer, and T levels increase above levels of individuals spawned in June. A spring peak in T in unspawned females and increasing levels in the fall correlate with estradiol (E) levels. Androgen levels do not correlate with the seasonal cycle in boatwhistle parameters suggesting that some other factor is responsible.
Sternopygus branco n. sp. is described from the Amazon River between its confluences with the Rios Japurá and Negro, and from the lower 100 km of the Rio Negro. This species is described using features of external morphology, meristics, pigmentation, osteology, and electric organ discharges (EODs). The new species is diagnosed by a very low EOD repetition rate (24–35 Hz vs approximately 40–300 Hz in congeners); very pale pigmentation on the entire body surface in live specimens; the absence of a pale lateral stripe along dorsal margin of anal-fin pterygiophores (present in adults and/or juveniles in all congeners); a slender body (body depth 8.3–10.9% length to end of anal fin vs 10.3–16.1% in congeners); posterior margins of cleithrum and supracleithrum short and robust. Sternopygus branco is found in the main river channels of whitewater and blackwater rivers and in adjacent side channels. It is not known from seasonally flooded forests or terra firme stream systems. Sternopygus branco is able to rapidly modulate the amplitude of its EOD.
A cladistic analysis of the gobiid fish genus Gobionellus primarily using characters of the postcranial axial skeleton and the cephalic lateralis system gave evidence that the genus as historically conceived is polyphyletic. Its present recognition relies upon characters common to many species of gobionelline gobies. One group of six species is most closely related to the genus Gobioides. This group includes Gobionellus oceanicus and retains the name Gobionellus. Gobionellus is diagnosed by an extensive oculoscapular canal running from the snout to above the rear margin of the operculum with a unique A‘BCDFHKL’ pore pattern, a distally flared fourth neural spine that is spatulate in five of the six species, a vertical row of neuromasts on the rear field of the operculum, and elongate gill rakers on the anterior surface and lobes on the posterior surface of the epibranchial of the first gill arch. No unequivocal synapomorphies are offered for the genus excluding Gobioides. Fifteen species previously assigned to Gobionellus are more closely related to species in the genera Oxyurichthys, Oligolepis, and Evorthodus. These species are removed to the resurrected genus Ctenogobius of which Ctenogobius fasciatus is the type species. Ctenogobius is diagnosed by an abbreviated oculoscapular canal that terminates above the preoperculum with an A‘BCDFH’ pattern, a simple or triangulate fourth neural spine, a diagonal posterior opercular neuromast row, and a lack of lobes or gill rakers on the anterior surface of the first epibranchial. The lack of lobes or gill rakers on the anterior surface of the first epibranchial is synapomorphic for the genus. One species originally placed in Gobionellus, Oxyurichthys stigmalophius, exhibits two synapomorphies diagnostic of Oxyurichthys—a transversely bifid third neural spine and no preopercular canal. It also shares other derived features found in most species of Oxyurichthys—a rounded margin on the tongue, a membranous crest on the nape, a shortened palatine bone, and a single row of teeth in the upper jaw. Putative synapomorphies of the gobionelline genera Evorthodus, Gobioides, Oligolepis, and Stenogobius are discussed.
The genus Gobionellus and its six included species are diagnosed and redescribed. All species share a unique cephalic lateralis canal structure, which extends from the tip of the snout to above the rear margin of the operculum with an A‘BCDFHKL’ pore pattern; a vertical row of sensory papillae on the rear field of the operculum and transverse suborbital rows; and a blunt, distally flared fourth neural spine that is spatulate in five of the six species. Three species are found in the eastern Pacific Ocean. Gobionellus daguae is known only from the lower portions of rivers in Panama and Colombia. Gobionellus liolepis has been collected in tidepools and on beaches along the coast of Panama, in the Miraflores locks, and over mud habitats up to 20 m deep off El Salvador. The third eastern Pacific species, Gobionellus microdon, is widespread in estuaries and in some fresh waters from Mexico to Ecuador. Gobionellus mystax is a junior synonym of this species. Two species are recognized from the western Atlantic Ocean. Gobionellus oceanicus is found in estuaries and inshore coastal waters from New Jersey to southern Brazil. The other species, Gobionellus stomatus, is limited to Brazilian estuaries. Gobionellus occidentalis is the only member of the genus from western Africa, where it inhabits tropical estuaries and coastal waters. A key to the species is provided.
A new species and a rare species of macrourid fishes are described from the upper continental slope off northeastern Taiwan at depths between 400 and 800 m. Caelorinchus leptorhinus n. sp. is most closely similar to Caelorinchus macrorhynchus (Smith and Radcliffe), differing mainly in having the underside of the snout almost entirely naked, in contrast to fully scaled in C. macrorhynchus, and some differences in proportional measurements. Caelorinchus brevirostris Okamura, previously known only from the holotype taken in the southern Ryukyu Islands, is redescribed from 11 specimens collected off northeastern Taiwan.
A new species of the skate genus Bathyraja, Bathyraja mariposa, is described from the Aleutian Islands and its geographic and bathymetric range documented. Bathyraja mariposa is similar to Bathyraja violacea and Rhinoraja taranetzi in its moderate maximum size and absence of thorns on the disc. However, it can be clearly distinguished from B. violacea by its distinctive color pattern, uniform covering of fine denticles, and clasper morphology. It can be distinguished from R. taranetzi and other similar western North Pacific species by the lack of a pseudosiphon on the clasper as well as by differences in various morphometric and meristic characters.
Pimelodella spelaea, new species, is described from a subterranean stream tributary to the São Bernardo River inside the São Bernardo Cave, in the São Domingos karst area, upper Tocantins River basin, central Brazil. The new species can be distinguished from its epigean (surface) congeners by derived troglomorphic features such as smaller eyes and fainter coloration, which are nevertheless less reduced than in the other known troglobitic (exclusively subterranean) species, Pimelodella kronei, from southeast Brazil. Ecological data such as habitat characteristics, population data based on mark-recapture techniques, and distributions of frequencies of standard length, weight, and condition factor, were obtained during the dry season of 2000 (May to September). A relatively high population density (about one individual per m−2) was recorded for the accessible habitat, which is probably much lower in the nonaccessible, phreatic area of distribution. The low condition factor recorded for P. spelaea, which tended to decrease along the study period, indicates a regime of severe food limitation, intensifying along the dry season. An allopatric model of differentiation is hypothesized, either because of topographic isolation or because of local extinction of epigean relatives, or both factors combined. The conservation status of the new species is also discussed.
A new species of softnose skate, Bathyraja cousseauae, is described from two adult and 19 juvenile specimens collected from different localities of the southwestern Atlantic. Bathyraja cousseauae is distinguished from all other southwestern Atlantic softnose skate species by its color pattern, squamation pattern of dorsal surface, lack of interspace between dorsal fins, and clasper morphology. The new species has a round pale area ocellus-like, margined with dark brown on posterior part of each pectoral base of dorsal surface, paler and dark spots over the disk, a continuous row of 21–27 median thorns from nuchal region to first dorsal fin and upper side of disc densely covered with dermal denticles. Males have rod-shaped claspers not expanded at proximal section of glans as it does in Bathyraja brachyurops. Besides the external morphological features, skeletal characteristics (neurocranium, scapulocoracoids, and claspers) are also described and illustrated here.
Callichthys serralabium, a new callichthyid catfish species, is described from drainages in the upper Orinoco River, near La Esmeralda, Venezuela and the headwaters of the Negro River, tributary of the Amazon River, both in Brazil and Venezuela. This species is readily distinguished from other Callichthys by possessing a serrated lower lip, 8–9 branched rays in the pectoral fin, an irregular color pattern of dark, diffuse blotches on flanks of adults, a longer anal-fin spine, and absence of the prenasal central plate. A key for the species of Callichthys is provided and some characters incongruent with the current phylogenetic hypothesis for the callichthyids are discussed.
We studied the effects of a pathogenic fungus (Batrachochytrium dendrobatidis; Chytridiomycota) on larval fitness in the Gray Treefrog (Hyla chrysoscelis). Recent studies have identified chytridiomycosis as an emerging infectious disease that poses a significant risk for amphibian populations worldwide. We also tested the effects of the heavy metal copper, a common environmental contaminant in aquatic environments, on larval fitness. We reared larvae in laboratory containers and tested whether exposure to copper and B. dendrobatidis affected Hyla survival, growth, and development. Neither exposure to B. dendrobatidis nor copper significantly affected survival to metamorphosis. Metamorphic body mass was significantly reduced in the presence of B. dendrobatidis, but copper did not significantly affect larval growth. Both copper and B. dendrobatidis exposure significantly increased larval period length, but copper differentially affected development in the presence of B. dendrobatidis. Hyla developed more slowly when reared in the presence of B. dendrobatidis in copper-free conditions or at a low copper concentration. This significant copper-by-disease interaction suggests that, for some traits, the impact of chytridiomycosis on larval amphibians may be affected by the presence of copper.
The phylogenetic and phylogeographic relationships of the North American cyprinid genus Erimystax were examined using sequences of the mitochondrial cytochrome b gene. Phylogenetic analyses were performed using parsimony and Bayesian approaches. Relationships within the genus were (((Erimystax cahni plus Erimystax x-punctatus)(Erimystax dissimilis plus Erimystax harryi))(Erimystax insignis))). Genetic distances among species were high and suggest that all speciation events occurred during the Miocene. Shallow divergence and wide geographic distribution in both E. x-punctatus and E. dissimilis suggest post-Pleistocene dispersal. Erimystax x-punctatus expanded its range northward into the upper Mississippi basin and eastward into the Ohio River basin from a putative Ozarkian refugium. Erimystax dissimilis expanded its range northward from a southern Appalachian refugium.
Reduction in locomotor performance during pregnancy is a potential cost of reproduction for female lizards and snakes. Most previous studies have suggested that reduced locomotor performance is a direct result of carrying a physical burden (the clutch). However, recent studies suggest that physiological changes associated with pregnancy can also cause a reduction in locomotor performance, particularly in viviparous species with prolonged gestation. I measured locomotor performance of the Northern Death Adder (Acanthophis praelongus), a viviparous, semiaquatic ambush foraging snake from tropical Australia. Swimming speeds of males and nonreproductive females were very similar, but late-term gravid females swam 30% more slowly than nonreproductive animals. Females with enlarged oviductal follicles carried physical burdens similar in size to those carried by gravid females but did not have impaired locomotor performance. Swimming speed of gravid females was unrelated to two measures of relative clutch mass. These results support the hypothesis that physiological changes during late pregnancy contribute to the decrement in locomotor performance during pregnancy. Because locomotor performance was uncorrelated with the level of reproductive investment, survival costs during pregnancy may be less important than previously thought, particularly if physiological costs during pregnancy render females vulnerable to starvation or predation following parturition. Additional field studies are needed to clarify the nature of survival costs in natural populations and their consequences for the evolution of squamate life histories.
Pterapogon kauderni, the Banggai Cardinalfish, demonstrates a marked ontogenetic shift in habitat and microhabitat use with new recruits differing significantly from older juveniles and adults. New recruits are commonly found in sea grass beds and associated with anemones, whereas older individuals and adults prefer coral reef habitat, and live coral or sea urchins as living substrates. This habitat segregation occurs within a small area, at the same depth, and it is related neither to a shift in feeding habits, nor to intraspecific competition. All size classes, including brooding males and mating pairs, overlap in habitat and microhabitat use. The processes behind this resource segregation are unclear, but the fact that P. kauderni lacks a larval period, and the embryos settle directly within the parental habitat, rules out any presettlement factor. Observations on various aspects of P. kauderni behavior indicate a likely combination of various processes acting together in determining its distribution patterns.
The habitat of a population of coastal goannas (Varanus panoptes) was assessed at Fog Bay, Australia, by a combination of scat analysis, radio tracking, burrow counts, and sightings. Tracks were followed to assess spatial and temporal beach use. Scat analyses showed that goannas ate a variety of prey from the beach and dunes. Sea turtle eggs were the dominant prey found in scats during the dry season. All four census methods showed that goannas selected the beach habitat and dunes, although habitat selection indices were highest for the beach. Goannas used the beach throughout the year with peak beach activity occurring in May and November. There was no indication that sea turtle nesting influenced the timing of beach activities or how long goannas spent on the beach. The seasonal activity patterns of V. panoptes at Fog Bay is unlike V. panoptes in other areas and appears to be related to food availability. Although goannas prey on a large portion of sea turtle nests on the Fog Bay mainland, more research is required on the demography of the sea turtles to assess whether this has impacts on the size of the sea turtle populations.
Hybrid individuals from naturally spawning populations of Apache Trout (Oncorhynchus gilae apache) and Rainbow Trout (Oncorhynchus mykiss) have been reported to hybridize successfully in only one direction. This is suggested by the absence of Rainbow Trout mitochondrial haplotypes in hybrid individuals. By artificially producing reciprocal crosses of Apache Trout and Rainbow Trout, the apparent unidirectional fertilization in naturally spawning hybrid populations was shown not to be the result of gametic incompatibility or early zygote death. Although survival rate differences between the reciprocal hybrid crosses were not significantly different, development rate differed significantly between the groups (P < 0.001). Using time to hatch as the indicator of development rate, Apache female by Rainbow male hybrids had a mean time to hatch seven days faster than Rainbow female by Apache male hybrids with both developing intermediate to the pure crosses. Although this could account for the perceived unidirectional hybridization in naturally spawning populations, it is more likely that some type of temporal or behavioral isolation accounts for the apparent directionality of the hybridization.
Reptile eggs from cool temperate environments often experience cool incubation conditions, which may have long-term consequences for individual fitness. We studied the effects of artificial incubation regimes on size, growth, and survival of New Zealand's only endemic oviparous lizard, Oligosoma suteri. Eggs were randomly distributed among three incubation temperatures (18, 22, 26 C) and two water potentials (−120 and −270 kPa). Hatchlings incubated at 22 C and −120 kPa were significantly larger for most measurements than hatchlings from other incubation treatments. Juveniles from the two higher incubation temperatures had more rapid growth and ultimately greater size by 12 months, as well as significantly higher survival to 18 months, than did 18 C incubated individuals. Hatchling size did not influence survival. Our data suggest that the restricted northern distribution of O. suteri results from ecological constraints caused by the negative effects of cool incubation temperatures on embryos and subsequently hatchlings.
Spinoid scales appear early in the development of Swordfish, Xiphias gladius, and are first discernable in the larval stage. Scales vary in form between two principal types: small single and multispined scales and large multispined scales. Unlike the typical teleostean condition, Xiphias scales are attached along their base, not at their proximal end within scale pockets. Scales persist in juveniles and adults, that is, scales are not shed or resorbed. Scales become more deeply embedded within the dermis as the dermis thickens in ontogeny; consequently only the tips of spines protrude through the dermis of adults. A network of mucous canals with regularly spaced pores to the exterior develop in the dermis of adults, and the mucus produced further insulates scales from the surface of the integument. The ontogeny of the squamation of Xiphias differs from that of the related Istiophoridae.
Diet and prey size relationships of Flathead Snakes (Tantilla gracilis) in the pine- hardwood forests of east Texas were determined on 68 individuals. Ninety-five percent of the snakes contained prey of which a large proportion was identifiable. Approximately 80% of the diet (by frequency) of T. gracilis consisted of coleopteran (beetle) larvae of the families Alleculidae, Elateridae, and Tenebrionidae. Other prey were centipedes and terrestrial snails. Correlation of prey size with snake size revealed a positive relationship, but accounts for little of the variation. Adults and juveniles ingested the same relative prey sizes with juvenile snakes predominately feeding on alleculid larvae and adults feeding on tenebrionid larvae. Larger snakes had a greater prey mass in their alimentary tracts; however, they did not consume significantly greater numbers of prey items. Direction of prey ingestion was primarily posterior first (72%). Because most of their prey have elongated bodies, it appears that T. gracilis responds to growth changes in body size by switching to different prey types. Choosing prey by size may be less important than prey shape for T. gracilis because of the morphological adaptations associated with a fossorial existence.
This paper reports field observations on dying or illness feigning by the Comb Grouper Mycteroperca acutirostris in shallow waters of the southeastern Brazil's coast, and comments on this unique hunting behavior, similar to death feigning previously recorded for a cichlid species in Africa. An individual preying on young fishes at dusk successfully employed this unusual feeding strategy during five sequential foraging bouts. No other M. acutirostris individual was observed feigning dying, a behavior that seems to be a modification of the stalking tactic.
We identify a fragmentary turtle specimen from the middle Miocene (MN 5) of Hambach, Germany, as the bridge peripheral of a carettochelyine turtle. This important find extends the fossil record of the group to the Neogene of Europe and calls into question the utility of fossil carettochelyids in identifying tropical climate zones.
The Bluemask Darter, Etheostoma (Doration) sp., is an endangered fish endemic to the upper Caney Fork system in the Cumberland River drainage in central Tennessee. Little is known about the life history of this species, and an understanding of its reproductive ecology is necessary to implement management and recovery actions. Spawning behavior and habitat were studied from 29 May to 1 July 2002 in the Collins River. Spawning events (n = 247) averaged 7.6 ± 0.1 sec, and intervals between spawning events averaged 127.0 ± 5.0 sec. Some age 1 individuals were sexually mature, but the majority of the reproductive population was comprised of older fish. Microhabitat use differed among nonspawning females, nonspawning males, and spawning pairs. Depths and water velocities differed significantly (P < 0.05) between areas occupied by lone females (n = 37), lone males (n = 45), and spawning pairs (n = 63). Spawning transpired in runs at mean water depths of 21.4 ± 0.4 cm, bottom velocities of 18.9 ± 0.4 cm/sec, and water column velocities of 28.9 ± 0.5 cm/sec. Substrate was dominated by gravel in areas occupied by lone males and spawning pairs, whereas most lone females were found over a sand- dominant substrate. Spawning microhabitats differed from habitats used during the summer.