Agra, arboreal beetles of Neotropical forests: mixta group, virgata group, and ohausi group systematics (Carabidae)

Abstract. This paper is the fifth in a series designed to cover taxono-mically all species-groups of the lebiine genus Agra , whose cumulative ranges extend from southernmost Texas to northernmost Argentina. The mixta, virgata, feisthameli and ohausi groups constitute Section Feisthameli of the genus, and a key to these groups is provided. The mixta group consists of two species which have a composite range extending from southeastern Brazil to middle Mexico; the virgata group consists of nine species which have a composite range extending from southeastern Brazil to Guatemala; and the ohausi group consists of four species which have a composite range restricted to southeastern Brazil. The speciose feisthameli group is covered in a separate paper.
Among the three groups in the present paper, eleven new species are described from the following type localities: perkinsorum (MEXICO, Nayarit, 17.6 km southwest of Compostela), vate (MEXICO, Veracruz, Los Tuxtlas, La Playa Escondida), nola (REPUBLIC OF PANAMA, Panama, Cerro Campana), cadabra (EQUADOR, Pichincha, 47 km south of Santo Domingo de los Colorados, Rio Palenque Station), chocha (WEST INDIES, Trinidad, Arima Valley), phainops (FRENCH GUIANA, Pariacabo), imaginis (BRAZIL, Goias, Jatahy), inca (PERU, Madre de Dios, Rio Tambopata Reserve, 30 km (air) southwest of Puerto Maldonado), itatiaya (BRAZIL, Rio de Janeiro, Parque Nacional Itatiaya), calamitas (BRAZIL, Bahia, Itamaraju), anthrax (BRAZIL, Espirito Santo, Parque Socretama). A dot map illustrates the range of each taxon.
Distribution and relationships are discussed in general, but detailed cladistic and biogeographic analysis is deferred until taxonomy of the four groups of Section Feisthameli is completed. Species distribution correspond to Pleistocene refuges suggested by other authors based on other groups and classes of organisms.     

Agra, arboreal beetles of Neotropical forests: feisthameli group systematics (Carabidae)

Abstract. This paper is the sixth in a series designed to cover taxonomically all species groups of Agra , whose cumulative ranges extend from southernmost Texas to northernmost Argentina. The feisthameli, mixta, virgata and ohausi groups constitute the Feisthameli Section of the genus. The feisthameli group consists of seventeen species which have a composite range extending from Guatemala to Bolivia and southeastern Brazil.
Among this group, nine new species are described from the following type localities: chapada (BRAZIL, Chapada de GuimaráTes), phite (BOLIVIA, Provencia de Gutierrez), para (BRAZIL, Pará), rubra (BRAZIL, Para, SáTo Félix do Xingu), dation (BRAZIL, Minas Gerais, Teófilo Otoni), tuitis (PERU, San Martin, Tarapoto), memnon (BRAZIL, Espírito Santo, SáTo Mateus), lata (BOLIVIA, Santa Cruz), magdalena (COLOMBIA, Santander). A dot map illustrates the range of each taxon.
Distribution and relationships are discussed in general, but detailed cladistic analysis is deferred until taxonomy of other sections is completed. Species distributions correspond in part to pleistocene refuges suggested by other authors based on other classes of organisms; however, more species occur outside such centres than in them.     

A new method for censusing animal populations: The number of Eciton burchelli army ant colonies on Barro Colorado Island,Panama

Summary A new technique for estimating the size of an animal population is described. This technique is used to provide an up to date estimate of the number of colonies of the army ant Eciton burchelli on Barro Colorado Island, Panama. There have been approximately 50 colonies of this species on Barro Colorado Island for more than thirty years. The relative constancy of this population is contrasted with the great temporal variability of other tropical insect populations.     

Fruit production,migrant bird visitation,and seed dispersal of Guarea glabra in Panama

Summary The relationship between bird visitation and the size of the available fruit crop was studied at an understory tree (Guarea glabra Vahl, Meliaceae) in the tropical wet forest of Barro Colorado Island, Panama Canal Zone. Twelve resident species and seven North American migrant species fed on the Bright orange arilloids (seeds with arils), which were not depleted during the normal fruiting period. The number of individual visitors, the number of visiting species, and the number of seeds removed increased linearly with the size of the available fruit crop. The proportion of seeds removed did not increase with the size of the available fruit crop, indicating that dispersal is a function of the number of fruit available and not a disproportionate function of large fruit displays. Four species of North American migrants (Myiarchus crinitus, Catharus ustulatus, Vireo olivaceus, and Vermivora peregrina) accounted for 70% of the visits and 60% of the seeds removed from the trees. No resident species visited Guarea as frequently as any one of these migrants. There was no indication that any single visitor was dependent on this tree for nutrition, nor that the tree was dependent upon any single species for dispersal. We hypothesize that the fruiting season of G. glabra is adaptively synchronized with northward migration of opportunistically frugivorous North American birds.     

Population density and use of space in howling monkeys (Alouatta villosa) in southwestern Panama

Eight troops ofAlouatta villosa (= A. palliata) were studied for 10 weeks in a natural forest in southwestern Panama. This is one of the few extended studies on the species to be conducted in a location other than Barro Colorado Island. The 151 animals belonging to 8 troops and 6 additional isolates utilized 37 acres of forest. This population density was 21 times greater than on Barro Colorado in 1932 and 12 times than on Barro Colorado in 1967. The average troop size was 18.9 animals; the average home range was 12.1 acres. Home ranges overlapped extensively and on the average troops had only 6% of their home range for exclusive use. There were no signs that the howling monkeys were exhausting their food supply or were experiencing decreased fertility. Several factors that could function in population control are evaluated.     

An example of “apparent” dominance-submission behavior between adult male howler monkeys (Alouatta palliata)

On Barro Colorado Island, Panama, two adult male howler monkeys (Alouatta palliata) belonging to the same troop were observed performing a sequence of behaviors typical of dominance-submission situations. The occurrence of these behaviors supports the hypothesis of an agegraded-male social organization for this species. There may also be a correlation between the appearance of these newly-reported behaviors and high population densities.     

Seasonal reproductive strategies in some Panamanian beetles

Thirteen species of Endomychidae (Coleoptera) were captured with a set of eight windowpane‐traps on Barro Colorado Island, Panama, during a period of three years. Their seasonal distribution, the development of their ovaries and testes, and their fat content was examined. With the possible exception of two species the data are consistent with the hypothesis of adult diapause for the latter part of the rainy season and the dry season, similar to that found for a related species Slenotarsus rotundus. It is suggested that the two aberrant species pass the adverse season in larval diapause.     

Group activity and population dynamics of the howler monkey on Barro Colorado Island

The mantled howler monkey (Alouatta palliata) of Barro Colorado Island, Panama Canal Zone, was studied in the late rainy season of 1970. Group ranges, group activity patterns and population size and structure were recorded for six groups in a 204 hectare study area. A new trail survey method was introduced to determine the population size of the entire island. Using this method, a population of 923±125 animals is estimated. Factors affecting group stability and group density are discussed. Rainfall appears to be a major determinant of howler activity and group movement in the late rainy season.     

Impact of Atta colombica Colonies on Understory Vegetation and Light Availability in a Neotropical Forest1

We quantified patterns of vegetation removal and light availability above Atta colombica nests on Barro Colorado Island, Panama. Ants cleared vegetation less than 1 cm in diameter from an area of 77 m², and up to 3 m above ground level. Overall light availability 1.5 m above ground level was 49 percent greater at ant nest sites than at sites in undisturbed understory. These higher light levels fell within the range known to enhance growth of both shade tolerant and pioneer species.     

Tree-rubbing behavior of a solitary male howler monkey

On Barro Colorado Island, Panama, a solitary male howler monkey (Alouatta palliata) was observed copulating with a female member of a troop. A unique tree-rubbing behavior was then performed by the male. Within two weeks he was the dominant male in that troop.     

Genetic structure of an isolated population of mantled howler monkeys (Alouatta palliata) on Barro Colorado Island, Panama

Habitat fragmentation may influence genetic variability through reductions in population size and the physical isolation of conspecifics. We explored the effects of these factors on genetic diversity in a population of mantled howler monkeys (Alouatta palliata) on Barro Colorado Island (BCI), Panama. The study population was established in 1914 when an unknown number of resident individuals were isolated from the surrounding mainland by damming of the Río Chagres to create the Panama Canal. Analyses of 10 microsatellite loci indicated that, despite this isolation, the howler monkeys on BCI exhibit levels of genetic diversity (H _S = 0.584 ± 0.063) among the highest reported for any species of Alouatta. These data also revealed that although relatedness among adults in a social group was significantly greater than zero, the BCI population is not highly genetically structured. Tests for genetic bottlenecks based on departures from equilibrium expectations failed to reveal evidence of a recent reduction in population size. In contrast, coalescent modeling indicated that this population has likely experienced a marked decline within the last few 100 years. These findings generate new insights into the genetic structure of A. palliata and suggest that while the formation of BCI may not have substantially reduced genetic variation in these animals, genetic diversity has been influenced by historical changes in population size.     

Predation-mediated Mortality of Early Life Stages: A Field Experiment with Nymphs of an Herbivorous Stick Insect (Metriophasma diocles)

We quantified predation pressure on first instar nymphs of a stick insect in predator‐exclusion experiments in the forest of Barro Colorado Island, Panamá. After considering intrinsic mortality (19%) and potential emigration (negligible), we estimated that 54 percent of the nymphs died due to predation in a two‐week period. Predation on nymphs was highest at night and may explain the low abundance of Metriophasma diodes in the understory.     

Seasonal and age-related differential mortality by sex in the Mantled Howler monkey,Alouatta palliata

Age-specific, differential mortality occurs between male and female mantled howler monkeys, Alouatta palliata,on Barro Colorado Island, Panama. A peak in mortality between 5 and 7 years is seen in males but not infernales. Dates when howler cadavers have been found suggest a seasonal mortality, with peaks in July and perhaps also in December through January.     

Eight microsatellite markers for the neotropical tree Luehea seemannii (Tiliaceae)

We isolated eight polymorphic microsatellites from the neotropical tree Luehea seemannii for gene flow and genetic structure studies. We used a streptavidin subtractive enrichment technique to develop a library of CA/GT repeats. Eight loci were screened for diversity from 96 individuals from Barro Colorado Island (BCI) and neighbouring Gigante peninsula in Panama. Luehea seemannii shows moderate levels of genetic diversity within these two populations. Allelic richness ranged from four to nine alleles and averaged 6.44 alleles per locus. Average expected heterozygosity was 0.65 on BCI and 0.60 on Gigante. Results are compared to microsatellite data from another wind‐dispersed gap colonizing species common in Panama.     

Resource patch size and flexible foraging in white-faced capuchins (Cebus capucinus)

White-faced capuchins (Cebus capucinus)on Barro Colorado Island, Panama, have a flexible foraging strategy. Typically, foraging party size is small and individuals feed dispersed from one another. When seasonal fruiting of large volume trees occurs, the majority of the group forages simultaneously. As C. capucinusdo not display a rigorous dominance structure and there are few indications that individuals or coalitions monopolize food patches,individuals are expected to display scramble strategies instead of high frequencies of contest competition. I recorded foraging party size (simultaneous foragers), the total number of animals to feed successively, and the diameter at breast height (DBH) of fruit trees used in two habituated troops. Individuals in each group spent a substantial amount of time — 65 and 48% of foraging time for each group — foraging in party sizes of one. Monkeys predominantly foraged alone in small trees (0- to 20- cm DBH), successively in medium trees (21- to 60- cm DBH), and simultaneously in large trees (>61- cm DBH). They used small trees more frequently than all other tree classes. In medium-sized trees, although fruit was plentiful, space was limited. In these trees Cebusforaged successively. In large-volume trees, space and fruit were abundant and several individuals fed together. As the DBH of fruiting trees increased, the average foraging party size increased exponentially. Cebus capucinusat Barro Colorado Island modify their foraging party size to adapt to the seasonal patterns of fruit production.     

The population characteristics of howler monkeys (Alouatta caraya) in Northern Argentina

Howler monkeys, Alouatta caraya, were collected in family groups from islands in the Rio Parana in northern Argentina. The body weights, lens weights, dental age and reproductive status of 261 individuals illustrated sexually dimorphic body weights after a period of accommodation as young adults, a large proportion of older females (even though there are more young adult males than females) and a higher percentage of pregnancies among these older females. Seventeen families, representing the entire social system of one island, showed that about three quarters were adult (equally divided between the sexes but with fewer older males than females) and the remaining quarter were immature (with an equal sex ratio). Half of the adult females were either pregnant or suckling young. The mean family size is seven which includes peripheral males. Group size and composition as well as adult to immature proportions compared closely with data on A. caraya in the Chaco of Argentina and the 1951 census of A. palliata on Barro Colorado Island. It can be said that when these two species of Alouatta occur in small size families, they have in common: a high proportion of adults to immature, a low proportion of infants, and can have either an equal sex ratio (A. caraya) or preponderance of females (A. palliata).     

崇明岛内河夏季鱼类群落组成及分布特征

崇明岛为世界最大的河口冲积沙岛,岛内河网水系发达。2018年6月,选择崇明岛内主要代表性河道包括北横引河、南横引河和竖河（庙港、堡镇港、八滧港）,设置16个固定站点,对内河鱼类开展了拖网调查,分析了崇明岛内河夏季鱼类群落组成及分布特征。调查期间共采集到鱼类4417尾,分属6目9科30种,主要为鲤形目鲤科鱼类;其中,淡水鱼类27种,洄游鱼类2种,近海鱼类1种。从空间分布来看,北横引河记录鱼类20种,南横引河记录鱼类17种,竖河记录鱼类18种,不同河道鱼类种类组成及优势种特征存在明显差异,其共有优势种为鲫Carassius auratus、似鳊Pseudobrama simoni和翘嘴红鲌Erythroculter ilishaeformis,部分种类只在特定的河段有记录。北横引河各站点平均物种数、丰度和生物量均高于南横引河和竖河,但3类河道间不存在显著差异（P>0.05）;主要优势种鲫、翘嘴红鲌和似鳊平均体长均以北横引河为最大,且在南横引河与北横引河中的个体体长均存在极显著差异（P<0.01）。聚类和排序分析结果表明,北横引河和南横引河鱼类组成差异较大,而竖河介于两者之间。相似性分析的结果也表明,南、北横引河鱼类群落结构差异极显著（R=0.524,P=0.008）,且这两组间鱼类种类组成的平均相异性最高,为43.92%,造成两组间差异的主要物种有10种（贡献率均大于5%）。综合来看,崇明岛内河鱼类群落组成与分布特征不同于一般的内陆河流,而具有河口型岛屿的特点。未来需要在长期监测基础上,综合多种因素,对崇明岛内河鱼类组成、分布、变化趋势及内在机理开展系统研究。     

El Niño and dry season rainfall influence hostplant phenology and an annual butterfly migration from Neotropical wet to dry forests

We censused butterflies flying across the Panama Canal at Barro Colorado Island (BCI) for 16 years and butterfly hostplants for 8 years to address the question: What environmental factors influence the timing and magnitude of migrating Aphrissa statira butterflies? The peak migration date was earlier when the wet season began earlier and when soil moisture content in the dry season preceding the migration was higher. The peak migration date was also positively associated with peak leaf flushing of one hostplant (Callichlamys latifolia) but not another (Xylophragma seemannianum). The quantity of migrants was correlated with the El Niño Southern Oscillation, which influenced April soil moisture on BCI and total rainfall in the dry season. Both hostplant species responded to El Niño with greater leaf flushing, and the number of adults deriving from or laying eggs on those new leaves was greatest during El Niño years. The year 1993 was exceptional in that the number of butterflies migrating was lower than predicted by the El Niño event, yet the dry season was unusually wet for an El Niño year as well. Thus, dry season rainfall appears to be a primary driver of larval food production and population outbreaks for A. statira. Understanding how global climate cycles and local weather influence tropical insect migrations improves the predictability of ecological effects of climate change.