Central Chiapas Research Articles

Early Mesoproterozoic inliers in the Chiapas Massif Complex of southern Mexico: Implications on Oaxaquia-Amazonia-Baltica configuration

In this contribution, zircon U-Pb geochronology by LA-ICPMS and Sm-Nd isotope systematics by TIMS are reported on metaigneous rocks from the central Chiapas Massif Complex (CMC), southern Mexico. The data reveal the existence of a Paleo- to early Mesoproterozoic crust that differs significantly from surrounding units and from typical Precambrian basement of Oaxaquia. On the basis of Sm-Nd depleted mantle model ages (TDM(Nd)) between 2.0 and 1.8 Ga a distinct crustal slice within the CMC is defined and named the Catarina Unit. It comprises banded felsic and mafic orthogneiss (amphibolite) yielding Calymmian U-Pb zircon ages, corresponding to igneous protolith crystallization between ∼1.58 and ∼1.50 Ga. Inherited zircon cores with 207Pb/206Pb apparent ages between ∼1.85 and ∼1.70 Ga and whole rock ɛNd(1.55Ga) values between + 1.2 and − 0.7 in granitic protoliths further suggest reworking of an older crustal component. Similarly, amphibolite has initial ɛNd(1.50Ga) ranging from + 2.8 to − 0.5, indicating only minor depleted mantle additions during the formation the mafic protoliths. Zircon overgrowths document a major Tonian thermotectonic event at ∼0.96–0.94 Ga that caused anatexis of Calymmian protoliths and intrusion of granitic melts (now biotite-amphibole quartz-feldspathic gneiss). Finally, all rocks underwent Permian-Triassic metamorphism and ductile deformation, commonly observed in the CMC. These results are interpreted in terms of an accretionary active margin established along the border of Amazonia in Calymmian times, where Catarina Unit protoliths formed by mixing of mantle-derived magmas with reworked cratonic crust. In Stenian times (1.2–1.1 Ga), the juvenile Oaxaquia arc accreted to the cratonic margin, followed by the collision between Amazonia and Baltica during final Rodinia amalgamation at ∼0.99 Ga. Subsequently, the newly formed orogen entered into a period of uplift, gravitational collapse, and relaxation similar to the Dalane phase in Baltica, leading to mantle upwelling and anatexis of the Catarina Unit at 0.96–0.94 Ga.

Population Ecology and Morphology of the Central Chiapas Mud Turtle (Kinosternon abaxillare)

The Central Chiapas Mud Turtle (Kinosternon abaxillare) is one of the least-studied turtles in Mexico. It is considered a microendemic, with a limited distribution in the Central Depression of Chiapas. In this article, we summarize its population ecology and provide a new assessment of its morphology from Villa Hidalgo, Chiapas, Mexico. We captured 168 individuals with 64 recaptures (232 total captures), and we report a population size of 231 individuals with a density of 700 turtles/ha (189 kg/ha standing crop biomass). The population showed a female-biased sex ratio (1:1.5) and the population structure was largely composed of adults. Finally, we provide a set of morphological measurements for all size classes and sexes of K. abaxillare for the first time. The plastral formula (relative lengths of midline plastral seams) was identical in all size classes and sexes (Ab > An > Gu > Hu > Fe > Pe). Females and males reached similar carapace length but not body mass. Further studies are needed to determine the overall conservation status of this range-restricted species.

Imitation games: The exchange and emulation of fine orange pottery in central Chiapas, Mexico

This article examines the complex production and exchange networks through which Central Chiapas polities manufactured and imported fine orange pottery. The Jovel Valley of highland Chiapas formed part of the western frontier of the Maya area, traditionally considered a relatively isolated periphery zone. Conversely, the neighboring Central Depression is considered by many scholars to be a corridor for trade, transportation and cultural contact, inhabited by Zoque cultural groups prior to occupation by Chiapanec-speaking people during the Postclassic period. Instrumental Neutron Activation Analysis (INAA) of fine orange pottery samples from sites in the Jovel Valley and Central Depression revealed that they were locally-produced imitations of Balancán Fine Orange ceramic serving dishes from the Lower Usumacinta River region, rather than imported vessels. Our results suggest that potters working independently in the Jovel Valley and Central Depression were making and locally exchanging imitation Balancán ceramics, using many different clay sources/recipes. An interpretive framework of isomorphism adapted from new institutional theory is useful for distinguishing the production of a standardized, elite-attributed, God-N-decorated set of vessels, from multiple, independent potters’ communities, all under the widespread stylistic influence of Balancán-style Fine Orange wares.

Biostratigraphy and paleoenvironment of Maastrichtian foraminiferal assemblages from a succession located NW of Tuxtla Gutiérrez, Chiapas (SE Mexico)

During the Maastrichtian, two lithostratigraphic units were deposited in the central Chiapas region; the Ocozocoautla and Angostura formations. The first unit crops out northwest of the city of Tuxtla Gutiérrez in central Chiapas. It is a complex lithological unit mainly composed of siliciclastic rocks interbedded with limestone. Overlying it, the Angostura limestone is recognized. This study focuses on a taxonomic study of the larger benthic and planktic foraminifera from both formations in order to assign age and to infer the paleoenviroment.
 The Ocozocoautla Formation includes an association of benthic as well as significant planktic foraminifera. Based on the microfossils stratigraphic distribution, two biozones were defined: the Pseudorbitoides rutteni–Ayalaina rutteni Assemblage Zone of earliest Maastrichtian and the upper part of the Gansserina gansseri Interval Zone of early Maastrichtian.
 The Angostura Formation contains dasycladacean algae and larger foraminifera considered as important age markers in shallow-water environments. Two foraminiferal interval zones were defined, Praechubbina breviclaustra Interval Zone of early late Maastrichtian and Chubbina jamaicensis Total Range Zone of late to latest Maastrichian age.
 The microfacies (grainstone, wackestone–packstone, wackestone) as well as the foraminiferal assemblage enable the paleoenvironment to be reconstructed, suggesting a deposit that developed in an open-water marine setting with moderate to high energy, characterized by benthic and planktic foraminifera in the Ocozocoautla Formation, while in the Angostura Formation a shallow-water marine protected environment is inferred.
 The paleobiogeographical distribution of the assemblage from both the Ocozocoautla and Angostura formations mostly contains endemic benthic foraminifera of the Caribbean Province and other few Tethysian forms of the Angostura Formation.

Slab flattening and tractional coupling drove Neogene clockwise rotation of Chiapas Massif, Mexico: Paleomagnetism of the Eocene El Bosque Formation

Dual-polarity characteristic magnetizations in red sandstones of the Early and Middle Eocene El Bosque Formation in central Chiapas, Mexico (D = 9.3° I = 23.6°; N = 19 selected sites, k = 32.6, α95 = 6.0°) indicate about 20° of clockwise rotation when compared with a coeval paleomagnetic reference pole in the North America craton. We interpret the rotation to result from traction between the base of the Chiapas Massif lithosphere and the low-angle subducting Cocos Plate. The northwest end of the massif overlies a shallower portion of the Cocos plate interface than the southeast end, which implies a greater amount and longer period of tractional coupling between the two plates in the northwest. We judge that the downdip, steep limb of the Cocos slab (beneath Gulf of Mexico) lies roughly in the regional mantle or hotspot reference frame. Assessments of Neogene North America-hotspot relative motion indicate an azimuth of ENE-WSW at 20 mm/yr, and thus we envisage that (1) the flat slab zone has been caused by the WSW telescoping of North America across the former geometry of the Cocos Benioff Zone, and (2) that the WNW end of the massif has undergone most tractional coupling with Cocos Plate than the ESE end. In turn, because the massif appears to have behaved as a rigid, unbroken body, this greater coupling has induced clockwise rotation that has been transferred as near-field shortening into the adjacent Sierra de Chiapas foldbelt.

A Funerary Cave at Moxviquil, Chiapas, Mexico

ABSTRACTThis article presents the excavation results of a funerary cave at the site of Moxviquil, located in the Jovel Valley of central highland Chiapas, Mexico. Diagnostic ceramics from funerary offerings suggest that the use of the cave spanned the principal occupation at the site, including Late Classic (a.d. 600–900) and Early Postclassic (a.d. 900–1250) periods. The offerings situate the Moxviquil cave within an extensive tradition of Mesoamerican sacred caves as funerary loci and situate the site itself within an extensive network of eastward- and westward-facing trade networks and political connections.

Late-latest Maastrichtian foraminiferal assemblage from the Angostura Platform, Chiapas, SE Mexico: Biostratigraphic, paleoenvironmental and paleobiogeographic significance

The carbonate platform deposits of the Angostura Formation are widely distributed in the central and eastern part of the Sierra de Chiapas, SE Mexico. The Angostura Formation contains a rich assemblage of foraminifera associated with mollusks (rudists, gastropods), corals, and dasycladacean green algae.A detailed foraminiferal study was carried out on samples from the El Coyol section of the Angostura succession. The studied section crops out in the El Coyol Hacienda located north of the Angostura dam, SE of the city of Tuxtla Gutiérrez in Central Chiapas. The foraminiferal assemblage consists mostly of benthic larger foraminifera but minor pelagic influence is represented by the presence of a number of planktic foraminifera.The benthic foraminiferal association is taxonomically diverse, being composed of Chubbina jamaicensis Robinson, Chubbina macgillavry Robinson, Caribealveolina michaudi Pêcheux, C. fourcadei Vicedo, Caus and Frijia, C. obesa (Fourcade and Fleury), Praechubbina breviclaustra Fourcade and Fleury, Omphalocyclus macroporus (Lamarck), Asterorbis rooki Vaughan and Cole, Vaughanina cubensis (Palmer), V. barkeri, Brönnimann, Sulcoperculina dickersoni (Palmer), S. globosa de Cizancourt, S. vermunti (Thiadens), Lepidorbitoides minima Douvillé, Orbitoides cf. O. apiculata Schlumberger, Planorbulina cretae (Marsson), Smoutina cruysi Drooger, and Nezzazatinella sp. In addition, the occurrence of Fleuryana adriatica De Castro, Drobne and Gušić, Rhapydionina cf. R. liburnica Stache, Cuneolina ketini Inan, Valvulina cf. V. triangularis d'Orbigny and Minouxia sp. is documented for the first time from the Angostura Formation.The planktic foraminifera are Rugoglobigerina macrocephala Brönnimann, R. cf. R. hexacamerata Brönnimann, R. rugosa (Plummer), Kuglerina rotundata (Brönnimmann), Muricohedbergella monmouthensis (Olson), Planoglobulina cf. P. carseyae (Plummer), Globotruncanita stuarti (de Lapparent), Globotruncanita pettersi (Gandolfi), Planoheterohelix globulosa (Ehrenberg), Pseudoguembelina sp., Macroglobigerinelloides prairielillensis (Pessagno) and the pithonellids Pithonella ovalis (Kaufmann) and P. sphaerica (Kaufmann). The age of the Angostura Formation in the studied section is late to latest Maastrichtian. A Chubbina jamaicensis Taxon Range Zone is proposed on the basis of the occurrence of the nominal taxon and foraminiferal association.The lithological and faunal evidence enable the paleoenvironment to be reconstructed. The microfacies (wackestone–packstone, wackestone–floatstone, wackestone, grainstone and packstone) as well as the foraminiferal assemblage suggest that the deposit was developed in a shallow water marine setting with low to moderate energy, with sporadic intercropping of an open platform deposit characterized by planktic foraminifera and pithonellids.The paleobiogeographical distribution of the foraminiferal association from the Angostura Formation contains cosmopolitan genera as well as endemic forms of the Caribbean Province from the Tethys Realm.

Genetic Tracing of Jatropha curcas L. from Its Mesoamerican Origin to the World.

Jatropha curcas L. (Jatropha), a shrub species of the family Euphorbiaceae, has been recognized as a promising biofuel plant for reducing greenhouse gas emissions. However, recent attempts at commercial cultivation in Africa and Asia have failed because of low productivity. It is important to elucidate genetic diversity and relationship in worldwide Jatropha genetic resources for breeding of better commercial cultivars. Here, genetic diversity was analyzed by using 246 accessions from Mesoamerica, Africa and Asia, based on 59 simple sequence repeat markers and eight retrotransposon-based insertion polymorphism markers. We found that central Chiapas of Mexico possesses the most diverse genetic resources, and the Chiapas Central Depression could be the center of origin. We identified three genetic groups in Mesoamerica, whose distribution revealed a distinct geographic cline. One of them consists mainly of accessions from central Chiapas. This suggests that it represents the original genetic group. We found two Veracruz accessions in another group, whose ancestors might be shipped from Port of Veracruz to the Old World, to be the source of all African and Asian Jatropha. Our results suggest the human selection that caused low productivity in Africa and Asia, and also breeding strategies to improve African and Asian Jatropha. Cultivars improved in the productivity will contribute to expand mass commercial cultivation of Jatropha in Africa and Asia to increase biofuel production, and finally will support in the battle against the climate change.

Nesting success of Turdus grayi (Passeriformes: Turdidae) at "El Zapotal" Recreational Ecological Preserve, Chiapas, Mexico.

Nesting success has been a surrogate to assess environmental changes that affect the reproductive success of birds, and to analyze changes that influence natality. We analyzed the nesting success of Turdus grayi at El Zapotal Recreational Ecological Preserve, Central Chiapas. During the 2015 breeding season, we intensively searched for active nests and evaluated habitat characteristics. We located a total of 56 nests of which 27 (48.2 %) were successful and 29 (51.7 %) were unsuccessful. Most unsuccessful nests (19) were depredated, while 8 (27.6 %) were abandoned and 2 (6.9 %) parasitized. Nesting success was 46 %. Depredation was the main mechanism of nest failure, mostly during incubation. We identified operating variables at site and patch scales. Through analysis of binary logistic regression models for each scale, we predicted which variables increased the probability of nesting success. We also performed a multivariate logistic regression analysis to rule out possible interactions among variables. At nest scale we found that nest height, ranging 4.2 - 5.1 m had increased nesting success, while at patch scale, the probability of nest success was greater at sites with a tree density ≥ 12. Our results indicated that the probability of nesting success did not show a relationship between scales. We suggest a decoupling between scales and mechanism. Thus, habitat changes occurring at local scale did not seem to interfere with the patch scale. Also, our results showed that variation in characteristics at nest scale could also influence depredation, when depredation had been presented at random, since nests with medium and high probability of being successful, failed also for this reason. Thus, in order to understand the factors, mechanisms and life history characteristics influencing nesting success, we suggest that in addition to the environmental variables, future studies should also consider the bird nesting behaviour.

Éxito de anidación de Turdus grayi (Passeriformes: Turdidae) en el Centro Ecológico Recreativo “El Zapotal”, Chiapas, México.

Nesting success has been a surrogate to assess environmental changes that affect the reproductive success of birds, and to analyze changes that influence natality. We analyzed the nesting success of Turdus grayi at "El Zapotal" Recreational Ecological Preserve, Central Chiapas. During the 2015 breeding season, we intensively searched for active nests and evaluated habitat characteristics. We located a total of 56 nests of which 27 (48.2 %) were successful and 29 (51.7 %) were unsuccessful. Most unsuccessful nests (19) were depredated, while 8 (27.6 %) were abandoned and 2 (6.9 %) parasitized. Nesting success was 46 %. Depredation was the main mechanism of nest failure, mostly during incubation. We identified operating variables at site and patch scales. Through analysis of binary logistic regression models for each scale, we predicted which variables increased the probability of nesting success. We also performed a multivariate logistic regression analysis to rule out possible interactions among variables. At nest scale we found that nest height, ranging 4.2 - 5.1 m had increased nesting success, while at patch scale, the probability of nest success was greater at sites with a tree density ≥ 12. Our results indicated that the probability of nesting success did not show a relationship between scales. We suggest a decoupling between scales and mechanism. Thus, habitat changes occurring at local scale did not seem to interfere with the patch scale. Also, our results showed that variation in characteristics at nest scale could also influence depredation, when depredation had been presented at random, since nests with medium and high probability of being successful, failed also for this reason. Thus, in order to understand the factors, mechanisms and life history characteristics influencing nesting success, we suggest that in addition to the environmental variables, future studies should also consider the bird nesting behaviour.

THE EMERGENCE OF STANDARDIZED SPATIAL PLANS IN SOUTHERN MESOAMERICA: CHRONOLOGY AND INTERREGIONAL INTERACTIONS VIEWED FROM CEIBAL, GUATEMALA

AbstractOur investigations at the lowland Maya center of Ceibal have demonstrated that a formal spatial pattern consisting of an E-Group assemblage and large platforms started around 1000b.c.and gradually expanded over the next several centuries. A re-evaluation of ceramic and radiocarbon data from other lowland Maya sites suggests that the beginning of sedentary life and ceramic use in various parts of the Maya lowlands started roughly simultaneously around 1000b.c., which may have been triggered by a change in maize productivity. The standardized spatial pattern including the E-Group assemblage probably developed in the Isthmian Interaction Sphere, encompassing the southern Gulf Coast, central Chiapas, the Chiapas-Guatemalan Pacific Coast, and Ceibal, during the transitional period between the decline of San Lorenzo and the rise of La Venta as a major center (1200–800b.c.). Most of the lowland Maya communities adopted the E-Group assemblage after 800b.c., but not other elements of the standardized spatial pattern.

AFTER 40 YEARS: REVISITING CEIBAL TO INVESTIGATE THE ORIGINS OF LOWLAND MAYA CIVILIZATION

AbstractThe Ceibal-Petexbatun Archaeological Project has been conducting field investigations at the lowland Maya site of Ceibal since 2005. Previous research at this site by Harvard University allowed us to develop detailed research designs geared toward specific research questions. A particularly important focus was the question of how lowland Maya civilization emerged and developed. Comparison with contemporaneous sites in central Chiapas led us to hypothesize that the residents of Ceibal established a formal spatial pattern similar to those of the Chiapas centers during the Middle Preclassic period (1000–350b.c.). Through excavations of important elements of this spatial pattern, including a probable E-Group assemblage and large platforms, we examined how the Ceibal residents participated in interregional interactions with Chiapas, the Gulf Coast, and other areas, and how construction activities and architecture shaped the course of social change.

Estudio del sistema de producción de café (Coffea arabica L.) en la región Frailesca, Chiapas

Las zonas cafetaleras del estado de Chiapas se caracterizan por sus contrastes ambientales, técnicos, económicos y socioculturales, que influyen en la producción del grano. El objetivo de este estudio fue analizar la intervención del componente humano en el sistema de producción de café (Coffea arabica L.), específicamente en los aspectos de manejo del cultivo, ambientales y socioeconómicos en la región Frailesca, del estado chiapaneco. Para ello, se aplicaron 243 encuestas a los involucrados en la producción de café. Se identificó la necesidad de impulsar la tecnificación del cultivo, carencia de infraestructura adecuada para la atención del proceso de beneficiado del café y mal manejo de la plantación, poca o nula organización de los productores para facilitar la consecución de créditos accesibles, falta de asesoría técnica para la transformación de la producción de café convencional a café orgánico, conservación delsuelo y manejo adecuado del agua en beneficio húmedo. La identificación de estas dificultades para hacer rentable el cultivo de café permiten planificar el manejo del sistema de producción de café y con ello satisfacer las exigencias del mercado en términos de calidad e inocuidad. Archivo XML (SciELO)

Efficacy of social support on metabolic syndrome among low income rural women in Chiapas, México.

The purpose of this study was to assess a social support intervention among rural women from Chiapas and its ability to change lifestyles, self-concept, and Metabolic Syndrome (MS). A convenience sample was conducted among older than 16 yo women from a marginalized rural community from central Chiapas. Two questionnaires were used, a self-concept questionnaire and a healthy lifestyle profile. Criteria for components of MS used were those of the International Diabetes Federation. The intervention was conducted over a three month period and divided into 13 sessions that concentrated on social support and were complemented by nutrition education modules. Five hundred eighty six participants met inclusion criteria for the study. At basal time 47% had MS; abdominal obesity, 69%; high levels of glucose, 27%; triglycerides, 56%; systolic blood pressure, 17%; diastolic blood pressure, 15%; and low levels of HDL-cholesterol, 55%. After the intervention, 38% had MS and significant differences were observed in all of the components of MS. The pre and post-intervention dimension scores on the self-concept form 5 (AF5), or self-concept questionnaire, and the Pender Health Promotion and Lifestyle Questionnaire (PETS-1) also yielded significant differences. After a three month social support and nutrition education intervention, significant changes were observed in several dimensions of the AF5 and PETS-1, as well as in MS and its components.

Restoring forest landscapes for biodiversity conservation and rural livelihoods: A spatial optimisation model

Conserving nature in the presence of humans is especially challenging in areas where livelihoods are largely based on locally available natural resources. The restoration of forests in such contexts calls for the identification of sites and actions that improve biodiversity protection, and ensure the provision of and accessibility to other forest-related ecosystem services. This paper introduces an integer-linear programming (ILP) approach to identify reforestation priorities that achieve such goals. Applications of ILP to nature conservation are many, but only a few of them deal with the problem of restoration, and none of the available models considers the basic needs of the local population. Given constraints on a restoration budget, the potential conversion of productive lands and the travel time to reach harvestable forest, the model maximises the amount of reforestation area (weighted by priority values) and minimises the harvesting of existing forest, while ensuring the conservation of landscape diversity, the satisfaction of timber demands and the stabilisation of erosion-prone land. As an input, suitability maps, generated through a combination of ecological criteria, are used to prioritise the selection of reforestation sites. An application to a 430 km 2 area in Central Chiapas (Mexico) resulted in compact patches and thus a manageable reforestation plan. Acceptable trade-offs were found between the amount of soil stabilisation possible and the prioritisation goals, while uncertainty in the prioritisation scores did not significantly affect the results. We show that restoration actions can be spatially designed to benefit both nature and people with minimal losses on both sides.

Jurassic volcanic and sedimentary rocks of the La Silla and Todos Santos Formations, Chiapas: Record of Nazas arc magmatism and rift-basin formation prior to opening of the Gulf of Mexico

Stratigraphic relationships, detrital zircon provenance, U-Pb and 40 Ar/ 39 Ar geochronology, and trace element geochemistry in volcanic and sedimentary rocks of the Sierra homocline of central Chiapas near La Angostura reservoir in Mexico document an extensive pulse of Early–Middle Jurassic arc magmatism in rocks that overlie and intrude the Permian–Triassic Chiapas massif. Upper Jurassic rift-basin strata unconformably overlie the volcanic rocks and the massif. A Pliensbachian U-Pb (zircon) SHRIMP (sensitive high-resolution ion microprobe) age from porphyritic andesite (191.0 ± 3.0 Ma), Early to Middle Jurassic 40 Ar/ 39 Ar dates from andesitic dikes, U-Pb grain ages of detrital zircons in overlying strata (196–161 Ma), and previously reported K-Ar dates indicate that subduction-related magmatism occurred in the western portion of the Maya block from Early to latest Middle Jurassic time. We assign the volcanic rocks to the La Silla Formation, which correlates with the informal Pueblo Viejo andesite of the Cintalapa and Uzpanapa regions to the northwest. La Silla magmatism predates opening of the Gulf of Mexico Basin. The Todos Santos Formation, which overlies La Silla Formation, was deposited in extensional basins during the early stages of gulf opening. We recognize a lower El Diamante Member of the Todos Santos, consisting of red fluvial sandstone, mudstone, and minor conglomerate containing primarily volcanic-lithic detritus; this member is characterized by a nearly unimodal Jurassic detrital zircon age population that indicates a Callovian or younger depositional age. Volcanic activity continued into the upper part of the El Diamante Member, but with a more mafic character. We also recognize an upper member, which we term the Jerico Member. This member is characterized by thickly bedded, coarse-grained pebbly arkose intercalated with several thick intervals (tens of meters) of conglomerate and pebbly sandstone. Sandstone petrology indicates a source in the granitic rocks of the Chiapas massif, with a tendency to show deep-seated sources and a diverse zircon population in the upper part of the section. The upper Todos Santos Formation in the study area is gradational into the overlying San Ricardo Formation (Kimmeridgian–Tithonian). The La Silla Formation was deposited in volcanic-complex environments, with a clear lack of differentiated volcanic rocks. Fluvial strata of the El Diamante Member were deposited in a mud-rich sinuous river system. The Jerico Member was deposited in large, sand-rich fluvial systems, which probably represent deposits of rift-axis trunk streams; conglomerate facies were deposited in adjacent and interfingering alluvial fan systems. We suggest that the stratigraphic record of the western Maya block records a transition from volcanic arc to intra-arc basin and subsequently to rift basin during Pliensbachian to Oxfordian time.

Re-Evaluation Of The Geographic Distribution And Phylogeography Of the Sigmodon hispidus Complex Based On Mitochondrial Dna Sequences

Geographic distribution among members of the Sigmodon hispidus complex (Sigmodon hirsutus, S. hispidus, and S. toltecus) were examined using DNA sequences from the mitochondrial cytochrome-b gene. Geographic distribution of each taxon was defined based on DNA sequences obtained from 69 samples (19 newly obtained and 50 from previous studies) collected from North, Central, and South America. These data indicated that S. hispidus is restricted to the southern one-half of the United States and northeastern Mexico (Nuevo León and Tamaulipas), S. toltecus occupies the eastern one-third of Mexico (central Tamaulipas) to northern Honduras, and S. hirsutus is distributed from central Chiapas and southeastern Oaxaca to northern South America (Venezuela). The newly collected data extend distributions of S. hispidus from the southern United States southward into northeastern Mexico and that of S. toltecus from Chiapas, Mexico, southward to Honduras. Genetic divergence and patterns of phylogeography were examined within each taxon.

Survey and Conservation of a Relict Population of Spider Monkeys (Ateles Geoffroyi) in the Sumidero Canyon, Mexico

Habitat loss, hunting and the pet trade have caused significant reductions in the original distribution of spider monkeys ( Ateles spp.) in the Neotropics. Mexico harbors the northernmost distribution of this primate in the Neotropics, and information on the current location of remnant populations and on their demographic features in particularly scarce. In this paper we report the results of a month-long survey during the dry season of a population of spider monkeys ( Ateles geoffroyi vellerosus) existing in the rainforest vegetation of the Sumidero Canyon National Park in central Chiapas, Mexico. The 23km-long canyon was divided into five 5km-long segments and the rainforest vegetation at the edges of the river canyon was surveyed from a boat and on the ground for presence of spider monkeys. Surveys resulted in the detection of nine subgroups of spider monkeys in four of the 5km-long segments, for an estimated total population of 36 individuals. Average subgroup size ranged from 3−7 individuals, 28% of these were adult males, 36% were adult females, 28% were juveniles and 8% were infants. Relative abundance was estimated at 1.8 monkeys/km of river. The rainforest vegetation along the river canyon has a patchy distribution and patches are separated by the steep and very tall walls of the canyon. Spider monkeys were observed to move from patch to patch by climbing the walls of the canyon. This unusual behavior allows individual spider monkeys to secure food resources and to meet other conspecifics. Additional surveys are necessary to map annual fluctuations in the size and distribution of the spider monkey population in the canyon.

Diversidad de aves de hábitats naturales y modificados en un paisaje de la Depresión Central de Chiapas, México

In many parts of the neotropics, the original habitats are rapidly changing because of excessive logging, agriculture and livestock activity, with an often negative impact on bird communities. I present an analysis of the diversity and richness of birds in a fragmented landscape of the Central Chiapas Depression. Fieldwork was conducted from February 2003 to January 2004. Using point counts, a total of 35 families and 225 bird species were registered (164 residents and 61 migratory); 3% are abundant and 30% rare. Diversity, species richness and number of individuals were significantly higher in tropical deciduous forest (H'=3.41, 178 species ANOVA p<0.0001), which also had the greatest number of species restricted to a single vegetation type (39 species). The incorporation and maintenance of natural and modified habitats are necessary for the survival and reproduction of many birds species in the study area.

NEW REPORTS OF ENDANGERED CHAMAEDOREA SPECIES (ARECACEAE) FROM SOUTHEASTERN MEXICO, WITH NOTES ON CONSERVATION STATUS, HABITAT, AND DISTRIBUTION

Abstract Chamaedorea glaucifolia, previously thought to be distributed in the Depresion Central de Chiapas and the adjacent Sierra Norte, is reported for the first time in southern Veracruz State in an evergreen tropical rain forest of the Uxpanapa region. It has also been found in the Sierra Madre del Sur, Chiapas, thus extending its range considerably. Chamaedorea tuerckheimii, previously known only from Guatemala and the Los Tuxtla region of Veracruz, was found in the northern mountain ranges of Chiapas and extending its range to a locality in the southern mountains of Tabasco bordering Chiapas. Notes on habitat and distribution are presented, as well as a “Critically Endangered” Red List Category (C1a) recommendation for C. tuerckheimii.