Chrysogaster

Abstract: The eastern water rat, Hydromys chrysogaster, lives in inland waters, estuaries, sea beaches and islands from Queensland to South Australia and Tasmania. It is adapted to semiaquatic life and changes in its molar teeth may be an adaptation to diet of crustaceans and molluscs. The present study was of 408 stomach contents and 316 contents of caecum with rectum, collected in New South Wales in 1970-73 from permanent Typha swamp. From elsewhere there were 12 other stomach and 11 gut contents and live rats were observed. At any time of day but particularly in evenings the rats swam along the bank or between logs or reed clumps, foraging and catching fish. Captive rats crushed small mussels and left large mussels to open by exposure. Diet varied with season and included crustaceans, mostly the yabbie, a crayfish (Cherax destructor), spiders, all Araneida with one identified as of the suborder Pisauridae, a fishing spider. Insects were the main food and were eaten in all seasons, and included larvae, nymphs and adults. Only 1% of rats had the freshwater mussel Veksurio ambiguus but the flesh was difficult to identify and empty shells were often found. Fish were eaten all the year, and were found in up to 35% of rats in autumn and winter; fish may be underestimated because flesh is not easily recognised and hard parts are not much eaten. Several species of fish, mostly introduced, were identified, their ages estimated from their scales, and length was calculated to be up to 36 cm. Frogs and macquaria tortoise (Emydura macquarii) were eaten. Birds were eaten all the year and were in up to 10% of stomachs in winter. Personal communications are quoted, from persons having seen H. chrysogaster capture large adult birds including duck and mutton bird (Puffinus tenuirostris). Captive rats were able to open cracked hen's eggs but left intact eggs. Plant material was eaten as food and possibly also in stomachs of prey. For 3 rats half the starch content was plant; 3 other stomachs had 5, 40 and 50% plant material, Azolla fuliculoides. Differences in diet with age are described. H. chrysogaster was an adaptable and opportunist feeder, making use of transient plenty of insects, exploiting plagues among other species and using plants during shortage of food. They may control introduced pests such as perch, or control yabbies in irrigation ditches.

Abstract: Morphometric variation of 17 wild troutpopulations of the genus Oncorhynchusfrom northwestern Mexico was analyzed.We used 25 standardized morphometric characters following a box truss protocol. In thediscriminant function analysis (DFA) of theexamined specimens (n = 214), grouped bydrainage, the canonical root 1 explained 88.1%of the total variation. Sixteen linearcharacters allow distinguishing O. mykissnelsoni (Sierra San Pedro Martir [SSPM])from O. chrysogaster and O. mykisssspp. (Sierra Madre Occidental [SMO]). Twodistinctive groups of populations wererecognized on the basis of the squaredMahalanobis' distances, one for the SSPM (O. m. nelsoni) and the other for the SMO. Thelatter group is divided into four subgroups:(1) O. chrysogaster (Rio Fuerte andRio Culiacan) and O. mykiss ssp.(Rio Piaxtla); (2) O. mykiss sspp.(Rio San Lorenzo, Rio Baluarte, andRio Acaponeta); (3) O. mykiss sspp.(Rio Yaqui and Rio Mayo); and (4) O. chrysogaster (Rio Sinaloa). In the DFAamong populations within each taxon, thecanonical variable 1 accounted for 41.8% ofthe total variation for O. m. nelsoni,59.4% for O. chrysogaster, and 43.8%for O. m. sspp.

Abstract: Diel feeding chronologies in two desert fishes, Agosia chrysogaster (longfin dace) and Pantosteus clarki (Gila mountain sucker), were determined by examining the foregut contents of fishes taken from Sycamore Creek, Maricopa Co., Arizona. A comparison of algae in foreguts with algae collected from the stream suggests that these species have distinct feeding chronologies and foraging areas. Pantosteus clarki consumes benthic diatoms and small amounts of detritus while A. chrysogaster feeds on filamentous green algae, benthic and epiphytic diatoms, and detri- tus. Peaks of ingested food volume indicate that A. chrysogaster is a diurnal feeder whereas P. clarki feeds both day and night, with crepuscular peaks. Fishes may assume an important role in ecosystem metabolism through feeding activities. To evaluate their role in the metabolism of a desert

Abstract: The Turks Island Boa (Epicrates c. chrysogaster) is endemic to the Turks and Caicos Islands and is currently known from only 11 islands. The subspecies has likely been extirpated from several islands in its historic range, and all remaining populations are threatened with extirpation owing to habitat loss, introduced feral predators, malicious killing, and vehicle strikes. To assist conservation efforts, we undertook a genetic analysis of 53 individual E. c. chrysogaster, representing five island populations, with the goal of identifying existing population structure and genetic diversity. For each snake sampled, we sequenced one mitochondrial and two nuclear genes, resulting in 1591 bp of sequence, and screened nine microsatellite loci. All individuals were found to be monomorphic at the four microsatellite loci that amplified, and only three individuals were found to vary (by a single nucleotide polymorphism) in either nuclear gene. Nine mitochondrial haplotypes were found, with a maximum seque...