A plasma protein marker for population genetic studies of the desert tortoise ( Xerobates agassizi )

Fifty-seven individual plasma samples from desert tortoises ( Xerobates agassizi ) representing 10 separate populations were analyzed by polyacrylamide gel electrophoresis using alkaline buffers. An albumin-like protein was found to be polymorphic for two electromorphs in northern populations inhabiting the Mohave Desert Province while Sonoran Desert populations to the south were monomorphic. The genetic divergence demonstrated in this survey is similar to earlier studies and provides evidence for the Colorado River as a potential barrier to gene flow among tortoise populations. These data suggest that tortoise plasma, examined by various electrophoretic methods, may provide a nondestructive means of determining the broad regional origin of desert tortoises.     

Comparison of distribution and habitat characteristics between an endemic and a wide-ranging cryptic species of Peromyscus on the Baja California Peninsula

Peromyscus eva and Peromyscus fraterculus are 2 morphologically similar species of the Peromyscus eremicus group occurring on the Baja California Peninsula. Due to the similarity between these 2 species, their ranges have been greatly confused; consequently, the specific habitat characteristics for each group are not well known. The goal of this study was to assess distribution ranges and characteristics of preferred habitats for P. eva and P. fraterculus in more detail. We identified taxonomy of individuals by evaluating genetic patterns produced by restriction fragment length polymorphisms (RFLPs). We evaluated the banding pattern generated by Alu I and Bam HI restriction enzymes in an 850-bp cytochrome b fragment. Consistent differences in number and size of fragments allowed for discrimination of individuals to species. The heterogeneity and evenness indexes showed that the microhabitat of P. fraterculus contained less-diverse soil types and is more homogeneous than the microhabitat of P. eva. In the state of Baja California Sur, P. eva occurs exclusively in the flat areas along the Pacific coast from the Vizcaino Desert to the south, including Margarita Island, with one small population in the Loreto area adjacent to Carmen Island. The habitats occupied by P. eva were heterogeneous (areas with friable, soft sandy soil and a low percentage of small stones). Peromyscus fraterculus occurs mostly in Baja California Norte, with some populations distributed in Baja California Sur, particularly in the western areas of the Vizcaino Desert along the mountain range, in the gulf side of the peninsula south of the city of La Paz, and in a small area on the eastern side of Sierra de Las Cruces. This species was mostly found on hard soil with high medium-size stone content.     

Late fall and early spring bird observations for Mulegé, Baja California Sur, Mexico

Observational data from spring and fall 1996 and spring 1997 for the region near Mulegé, Baja California Sur, Mexico, are summarized in tabular form. In addition, new or noteworthy data for 17 species are annotated to provide clarification of previously published records. A uniquely plumaged bird, too far south for a female American Robin ( Turdus migratorius ) in basic plumage and too far north for the endemic ""San Lucas"" Robin ( Turdus migratorius confinis ) and intermediate in coloration between the two, was recorded. Range expansions are documented for several species including the European Starling ( Sturnus vulgaris ), Anna's Hummingbird ( Calypte anna ), Western Meadowlark ( Sturnella neglecta ), White-faced Ibis ( Plegadis chichi ), and White-fronted Goose ( Anser albifrons ). Lease Grebes ( Tachybaptus dominicus ), a species of concern which is apparently declining in numbers, and Belding's Yellowthroat ( Geothlypis beldingi ) a species endemic to Baja California Sur, were observed in the freshwater marsh during all 3 study periods.     

A new subspecies of the snake Lichanura trivirgata from Cedros Island, Mexico

A new subspecies, Lichanura trivirgata bostici, from Cedros Island, Baja California del Norte, Mexico, is described, figured, and compared to other taxa of the genus.     

The centipede genus Arthrorhabdus Pocock, 1891, in the Western Hemisphere: potential occurrence of A. pygmaeus (Pocock, 1895) in Belize (Scolopendromorpha: Scolopendridae: Scolopendrinae)

The scolopendrid centipede genus Arthrorhabdus Pocock, 1891, comprises 6 species: A. formosus Pocock, 1891, the type species, occurring in southern Africa (Mpumalanga, Free State, Western and Northern Cape Provinces, South Africa, and southern Namibia); A. somalus Manfredi, 1933, in Somalia and Yemen; A. jonesii Verhoeff, 1938, from southern India (Kerala Province); A. mjobergi Kraepelin, 1916, and A. paucispinus Koch, 1984, in Australia (Western and South Australia, Northern Territory, and Queensland); and A. pygmaeus (Pocock, 1895), in the south central and southwestern United States, Mexico, and, potentially, Belize. This sporadic occurrence suggests that the genus is polyphyletic, and the monotypic synonym, Arthrorhabdinus Verhoeff, 1907, is available for pygmaeus , which is not referrable to another established genus. Arthrorhabdus spinifer (Kraepelin, 1903), known only from Belém, Pará State, Brazil, is transferred to Rhoda Meinert, 1886, thereby constituting a new combination. Sixteen new localities are reported for A. pygmaeus , 14 in Mexico and 2 in the U.S.; a specimen from Belize, intercepted in quarantine in Miami, suggests occurrence in this country. The 2 U.S. sites, in Cameron County, Texas, and Pima County, Arizona, extend the generic and specific ranges around 400 miles (640 km) to the southeast and west, respectively. In Mexico, A. pygmaeus ranges southward through the mainland, possibly excluding the Yucatan Peninsula, and also inhabits the southern half of Baja California Sur (BCS). Its apparent absence from the rest of the Baja peninsula suggests that the BCS populations may result from rafting across the Gulf of California from Sinaloa, where the species occurs.     

LXX.—New or little-known Tipulidæ (Diptera).—XXXIX. Australasian species

Summary

Evaporative cooling, through moistening of the eyes, panting, urinating and salivating, takes place in the spurred tortoise at high ambient temperatures. The mean temperature at which thermoregulatory salivation is initiated (39·5° ± 0·4°C) is constant, irrespective of body size, but the rate of panting is slower in heavier tortoises. Very small tortoises, however, do not pant for more than a few seconds.

Tortoises are inactive at 13°C and their body temperatures do not vary from the ambient. At 21° and 26°C, heat loss through transpiration exceeds metabolic heat production: at 33°C body temperatures are higher than the ambient. Increased range and variability at higher temperatures may be explained by the fact that spurred tortoises hold their breaths for long periods—a mechanism that could serve to reduce respiratory water loss. When breathing is actually taking place, however, the rate of respiration depends on body temperature: this grades into panting above 35°C.     

The taxonomic status of the rosy boa Lichanura roseofusca (Serpentes: Boidae)

Evidence is presented indicating that Lichanura roseofusca and Lichanura trivirgata are conspecific. Data include the report of an intermediate specimen from El Arco, Baja California Norte, a site midway between the previously known peninsular ranges of the two species; captive hybridization provides additional support for the conclusion.     

Status of an invading mainland jackrabbit on Cerralvo island, Gulf of California

We report the first observations of the black-tailed jackrabbit ( Lepus californicus ) on Cerralvo Island, Baja California Sur, Mexico. Evidence suggests a self-sustaining population. Analysis of available records indicates no previous record of Lepus on the island. Introduction of the jackrabbit to the island appears to have occurred between 1960 and 1991.     

Algal composition of microbiotic crusts from the Central Desert of Baja California, Mexico

A total of 66 algal species representing 32 genera were recovered from soils of 10 sites in the Catavi?a region of the Central Desert of Baja California, Mexico. The most common species encountered were the cyanophytes Nostoc commune and Schizothrix calcicola , the chlorophyte Myrmecia astigmatica , and the diatoms Hantzschia amphioxys, Hantzschia amphyoxys f. capitata, Luticola cohnii, Luticola mutica , and Pinnularia borealis var. scalarts . Nine species not found in any previous studies of North American desert soils were present in our study sites, including 3 taxa new to science: Cylindrocystis brebissonii var. deserti , var. nov.; Elakatothrix obtusata , sp. nov.; and Fasciculochloris mexicana , sp. nov. Attempts to correlate species composition with soil chemical and physical parameters were unsuccessful apart from a pH effect on cyanobacterial distribution. Overall composition of the soil algal community in the Catavi?a region is distinct from other desert sites we have studies, although some cosmopolitan desert soil taxa were present.     

Notes on Viscainopelmatus davewerneri (Orthoptera: Gryllacrididae; Stenopelmatinae) from the Viscaino Desert, Baja California Sur, Mexico

A male nymph in stadium 3 of Viscainopelmatus davewerneri Tinkham is reported and illustrated. The specimen was taken near Laguna Scammon, Baja California Sur, Mexico.     

Factors in palaeoclimate analysis based on the marine biota of the Conejo Volcanics (Miocene), Santa Monica Mountains,California

ABSTRACT

The fossils in the middle Miocene Conejo Volcanics lived on a middle to outer shelf at approximately 100 m depth. They were redeposited with their substrate sediment into a basin where submarine volcanic flows and hyaloclastic breccia were accumulating at bathyal depth. The sediments were deposited as lenses of primarily limestone but also sandstone. The complex depositional history of the biota within a tectonically active region provides the opportunity to investigate the diverse important factors essential in determining palaeoclimate. Palaeoclimate along the Pacific Coast during the Cenozoic has been largely determined by comparing the fossils with the biota diagnostic of present-day provinces. This is not possible for the Conejo Volcanics fauna because most of the shallow-water taxa on which the provinces are based are rare or absent in it, and because the regional palaeogeography that determined the Miocene provinces is not known. Geochemical data are essential to compensate for a lack of information about water depth and geography. A δ¹⁸O isotopic palaeotemperature of 15°C for a specimen of Amussiopecten in the Conejo Volcanics suggests a shallow-water setting off north-western Baja California. However at the depth at which the fossils lived, the equivalent present-day location would be farther south, off south-western Baja California. Incorporating the climatic effect of local Miocene geography, the modern equivalent latitudinal position of the Conejo Volcanics would be somewhat north of there, off central Baja California at 25 to 26°N. This location is about 9° south of the present location of the Conejo Volcanics and suggests that the marine climate was warmer in the mid-Miocene by about 5°C. However, because approximately one-half of the latitudinal difference is explained by tectonic translation through micro-plate rotation and San Andreas fault movement, the estimate of climatic change is correspondingly reduced to only a few degrees.     

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.     

The biological soil crusts of the San Nicolas Island: enigmatic algae from a geographically isolated ecosystem

Composite soil samples from 7 sites on San Nicolas Island were evaluated quantitatively and qualitatively for the presence of cyanobacteria and eukaryotic microalgae. Combined data demonstrated a rich algal flora with 19 cyanobacterial and 19 eukaryotic microalgal genera being identified, for a total of 56 species. Nine new species were identified and described among the cyanobacteria and the eukaryotic microalgae that were isolated: Leibleinia edaphica, Aphanothece maritima, Chroococcidiopsis edaphica, Cyanosarcina atroveneta, Hassallia californica, Hassallia pseudoramosissima, Microchaete terrestre, Palmellopsis californicus, and Pseudotetracystis compactis. Distinct distributional patterns of algal taxa existed among sites on the island and among soil algal floras of western North America. Some algal taxa appeared to be widely distributed across many desert regions, including Microcoleus vaginatus, Nostoc punctiforme, Nostoc paludosum, and Tolypothrix distorta, Chlorella vulgaris, Diplosphaera cf. chodatii, Myrmecia astigmatica, Myrmecia biatorellae, Hantzschia amphioxys, and Luticola mutica. Some taxa share a distinctly southern distribution with soil algae from southern Arizona, southern California, and Baja California (e.g., Scenedesmus deserticola and Eustigmatos magnus ). The data presented herein support the view that the cyanobacterial and microalgal floras of soil crusts possess significant biodiversity, much of it previously undescribed.     

Integrative taxonomy at the nexus of population divergence and speciation in insular speckled rattlesnakes

ABSTRACT

We describe two diminutive species of rattlesnakes (genus Crotalus) from small nearshore islands off the coast of Baja California in the western Gulf of California, Mexico. In order to test the hypothesis that some island populations represent cohesive species entities, we applied linear discriminant analysis and uniform validation procedures to multiple classes of intrinsic trait data. By using previously recognised species to establish a threshold for species recognition, we found that assignment of specimens to either new species was as probable as with other established rattlesnake species within the speckled rattlesnake (Crotalus mitchellii) complex. We also found that assignment of specimens from other island populations was not as probable as for the established species, and these populations are referable to C. pyrrhus. The species endemic to Piojo Island is most closely related to other island and mainland populations of C. pyrrhus whereas the species endemic to Cabeza de Caballo Island is apparently most closely related to C. angelensis, a nearby island endemic of large body size. However, patterns from both mitochondrial and nuclear phylogenies, and phenotypic variation, indicate that evolutionary trajectories of both of these species have been influenced by introgression from C. angelensis. We speculate that collective evidence based on contrasting patterns of nuclear and mitochondrial evolution supports a hybrid origin of the species from Cabeza de Caballo Island followed by exceptionally rapid mitochondrial evolution. Consistent with small body size, both species show a reduction in various scale counts relative to other species of the C. mitchellii species complex, suggesting that dwarfism is not simply a plastic response to insular conditions.

http://www.zoobank.org/urn.lsid:zoobank.org:pub:FBC8A11B-04A3-4231-85CA-3972DF5A42FF     

New records for hermatypic corals (Anthozoa: Scleractinia) in the Gulf of California,Mexico, with an historical and biogeographical discussion

This paper reports range extensions for seven hermatypic coral species in the Gulf of California. An analysis of the distribution and fossil record of the 12 hermatypic species of the Gulf shows that the coral communities of the Gulf are the oldest ones in the eastern Pacific. Two species have been recorded in the Gulf (or nearby) since the Pliocene and several other species since the Pleistocene. The uninterrupted fossil record falsifies the hypothesis of a total extinction of reef corals in the eastern Pacific during the Pleistocene. The fossil evidence and temperature calculations support the conjecture that the Gulf of California was a refuge zone for corals and other warm-water biotas during the same epoch. Also it is suggested that some species of the genera Porites may have an Atlantic origin, contrary to the accepted idea of an exclusive Indo-Pacific origin of the eastern Pacific coral fauna.