Review of the harvest mice (genus Reithrodontomys ) in the Mexican state of México

We examined 590 specimens of Reithrodontomys from 95 localities in the state of México. Four species of the subgenus Reithrodontomys and 1 of the subgenus Aporodon were identified. The former subgenus included R. chrysopsis , R. sumichrasti , R. megalotis , and R. fulvescens , which has 2 subspecies— R. f. toltecus and R. f. mustelinus — in the state. The representative of the subgenus Aporodon is R. microdon wagner , which is recorded for the first time in the state. We give information on taxonomy, morphometrics, reproduction, habitat characteristics, and related fauna. A discriminant analysis correctly classified 100% of specimens from the 6 taxa with 5 canonical variates, and accounted for 96.1% of the variance with the first 3 canonical variates.     

The distribution and ecology of Chirocephalus diaphanus Prévost (Branchiopoda: Anostraca) in Britain

The anostracan Chirocephalus diaphanus is at the northwestern limits of its range in Britain. Its distribution, based on records made since first reported nearly three centuries ago, is mapped. Aspects of its ecology and behaviour that have a bearing on its requirements, and therefore on the pattern of its distribution, are noted. It is an almost defenceless, opportunistic species, largely confined to temporary pools where it avoids predators. It occurs in those regions of Britain where a high winter water table is followed by a dry spring and early summer, and is essentially confined to the zone in which there is a deficit between precipitation and evapotranspiration during the six months April to September. Such conditions prevail in the south and southeast. Cooler, wetter, northern and western parts, with their more frequent rain-days and cloud cover, do not favour the formation of suitable temporary pools. The eurythermous nature of C. diaphanus, its ability to remain active at low temperatures, and its tolerance of a wide range of other conditions, enable it to exploit, and to reach maturity in, temporary pools before such predators as can colonize them have had the opportunity to do so. Dispersal and survival during ensuing periods of drought are effected by drought-resistant resting eggs. Possible genetic, reproductive and ecological constraints relevant to events that take place towards the edge of its range are noted.     

Extension of southern range and new specimens of the western gray squirrel, Sciurus griseus anthonyi (Mammalia: Sciuridae), in Baja California, México

We documented a southern range extension and new specimens of western gray squirrel ( Sciurus griseus anthonyi ) for the state of Baja California, México. The most recent specimen was collected in the town Cataviña and represents the southernmost record for the species and subspecies. Repeated observations of individuals in this new location suggest the presence of a marginal population in Mediterranean chaparral–desert scrub transition vegetation. Documentamos la extension de ámbito más sureño y nuevos especímenes de a ardilla gris occidental ( Sciurus griseus anthonyi ) para el Estado de Baja California, México. El espécimen más reciente fue recolectado en el poblado de Cataviña y representa el registro más sureño para la especie y subespecie. Observaciones repetidas de individuos en esta última localidad sureña sugiere la presencia de una población marginal en vegetación de transición de chaparral mediterráneo–matorral desértico.     

Rediscovered population of Mexican Plateau spotted whiptail lizard, Aspidoscelis septemvittata , from México, D.F.

Multiple surveys carried out by herpetologists in México, D.F., during the 1980s failed to find specimens of Aspidoscelis septemvitatta (Squamata: Teiidae). However, 10 specimens were recently collected to the east of México, D.F., inside a protected area, Sierra de Santa Catarina. The Sierra de Santa Catarina has been heavily modified by human activity and habitation. Morphological and natural history information about the specimens are presented, as well as notes on locality.     

Comparative demography of the high-altitude lizard, Sceloporus grammicus (Phrynosomatidae), on the Iztaccihuatl Volcano, Puebla, México

Population density, reproduction, and survivorship were compared between 2 populations of Sceloporus grammicus occurring at different altitudes (3700 m and 4400 m) on the eastern slopes of Iztaccihuatl Volcano, Puebla, México. Lizards in both populations matured at the same age (14-15 mon) and size (39-42 mm SLV). Population density was slightly greater at high altitude (131-163 per ha) than at low altitude (52-83 per ha). Survivorship and R o were higher at the low-altitude areas, but in general there were no significant demographic variations between altitudes that have been reported in lizard population at higher latitudes. Studies of lower-elevation populations might reveal some differences because previous studies indicated that litter size increases at lower altitudes, although they do not differ between our 3700 m and 4400 m populations.     

Feeding ecology of the giant otter (Pteronura brasiliensis) and the Neotropical otter (Lontra longicaudis) in Jaú National Park,Amazon, Brazil

This study compares the diets of the giant otter and the Neotropical otter, two Lutrinae species which feed mainly on fish. The study was carried out through the analyses of faecal samples collected between 2006 and 2008 (82 giant otter and 75 Neotropical otter) in the Jaú National Park. The giant otter feeds mainly on Cichlidae, Erythrinidae and Characidae, while the Neotropical otter consumes Doradidae, Loricariidae and Cichlidae. The two otter species had low diet similarity (Pianka’s Index = 0.16). The giant otter consumed larger fish than the Neotropical otter, which probably explores shallow river parts in search of small catfish. Prey other than fish were more frequent in the diet of the Neotropical otter, whereas giant otters ate a greater diversity of fish families. Increasing knowledge of the feeding habits and interactions of these two top-order predators is vital to determine appropriate protection and management policies.     

Current status of the non-indigenous molluscs in Chile,with the first record of Otala punctata (Müller, 1774) (Gastropoda: Helicidae) in the country and new records for Cornu aspersum (Müller, 1774) and Deroceras laeve (Müller, 1774)

A new introduced species, Otala punctata (Müller, 1774) and new records in Chile for Cornu aspersum (Müller, 1774) and Deroceras laeve (Müller, 1774) are documented based on surveys carried out in northern and central areas of the country. The presence and distribution of these alien species are complemented with a comprehensive compilation of all 34 non-indigenous species of marine, freshwater and terrestrial Mollusca in Chile; until 1999, only 16 alien species were known in Chile. Most of these alien species are found exclusively in transformed habitats, few exist in natural environments. The mechanism of introduction for the majority of these non-indigenous species is unknown; however, horticultural development, urban and suburban transformation of original natural habitats, and the aquarium trade are the most likely pathways of introduction. The highest threat of alien species is direct competition and predation of native molluscs, especially the small native land gastropods. Education and continuous field surveys are vital to detect and prevent their propagation as well as to avoid introduction of additional alien taxa.     

Population characteristics of four deep‐water pandalid shrimps (Decapoda: Caridea) in the northern Aegean Sea (NE Mediterranean)

The population characteristics of four deep‐water pandalid shrimps (Decapoda: Caridea) were studied in the northern Aegean Sea in samples collected annually (1997–2000) in summer, through experimental trawl, at depths down to 600 m. Females were larger than males in Plesionika martia and Plesionika heterocarpus; no significant differences in size of males and females were found in Chlorotocus crassicornis and Plesionika antigai. A trend of increasing size with depth was observed, as well as a linear increase in the proportion of females with increasing size. Sex ratio was skewed towards females at all depths in P. antigai, while in P. heterocarpus and C. crassicornis males dominated the intermediate depths. Negative allometries were apparent in the carapace length–weight relationships in males of all species. Isometric relationships were found in females apart from in P. heterocarpus. The population patterns conform to relevant Mediterranean reports. However, some population differences exist that may reflect the distinct environmental conditions prevailing in the study area.     

A comparison of some environmental adaptations of the littoral collembolans Anuridella marina (Willem) and Anurida maritima (Guérin)

Cuticle structures of A. marina and A. martima are discussed, the differences are correlated with a greater tolerance of desiccation in A. maritima. The cuticle ornamentation of A. maritima can trap a layer of water-saturated air thus slowing down water loss and allowing it to forage in the drier upper littoral, while A. marina, without a layer of water saturated air, is confined to more humid habitats in the lower littoral. Both species have a compressible macroplastron supported by major tubercles, as well as a much thinner microplastron supported by minor tubercles which is more resistant to wetting by pressure and surfactants. The plastrons are shown to be preadaptations to the littoral zone.     

Reproductive behaviour of Physalaemus kroyeri (Anura: Leiuperidae) in the municipality of Jequié, state of Bahia

From August 2010 to April 2011 we surveyed two different areas, located in the municipality of Jequié, State of Bahia, to obtain information about the reproductive biology of Physalaemus kroyeri. Data on the spatial and temporal distribution of P. kroyeri were recorded. Physalaemus kroyeri may be classified as a prolonged breeder with a reproductive period linked to rainfall. The average number of eggs in the foam nest of P. kroyeri is one of the highest recorded for the genus. Our results are coincident with the known reproductive behaviour of congeneric species and may be viewed as reproductive adaptations to open and highly seasonal environments.     

A note on the feeding of Simocephalus vetulus (O. F. Müller) (Crustacea; Cladocera) in light and dark

Summary

Simocephalus vetulus can be reared in the dark on a diet of Scenedesmus, but not on a pure culture of Chlamydomonas moewusii, unless the latter is frequently stirred. This failure appears to result from the ability of this alga to adhere to the sides and bottom of the culture vessel where the cladoceran is apparently unable to ingest it.     

Population dynamics of the bark-dwelling spider Eustala perfida Mello-Leitão, 1947 (Araneidae)

Population dynamics of spiders may vary according to biotic and abiotic factors. We studied the phenology of the bark-dwelling spider Eustala perfida over a two-year period and investigated how temperature, precipitation, and prey availability were associated with the population of this species. The population of E. perfida presented a well-defined fluctuation, with one reproductive cycle per year. The recruitment of spiders occurred in summer, followed by successive phenological peaks at all stages of development. The species is protogynic, and the population of adult males peaks in the cold/dry season, indicating a winter mature phenological pattern. The diet of E. perfida is composed mainly of medium-sized homopterans, complemented by small dipterans and hymenopterans. We found that the higher abundance of spiders occurred two months after the highest values of precipitation and temperature, and three months after the higher abundance of potential prey items. These results indicate that spiders require time to respond to changes in environmental conditions. The species’ natural history and the structure of the trunks in which it lives may also affect the number of individuals in a particular area and over time.