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Climatic seasonality drives ecosystem processes (e.g. productivity) and influences plant species distribution. However, it is poorly understood how different aspects of seasonality (especially regarding temperature and precipitation) affect growth continuity of trees in climates with low seasonality because seasonality is often only crudely measured. On islands, exceptionally wide elevational species distribution ranges allow the use of tree rings to identify how growth continuity and climate–growth relationships change with elevation. Here, we present a novel dendroecological method to measure stem growth continuity based on annual density fluctuations (ADFs) in tree rings of Pinus canariensis to indicate low climatic seasonality. The species ranges from 300 to >2000 m a.s.l. on the trade wind-influenced island of La Palma (Canary Islands), where we measured three decades of tree-ring data of 100 individuals distributed over 10 sites along the entire elevational range. The successfully implemented ADF approach revealed a major shift of stem growth continuity across the elevational gradient. In a remarkably clear pattern, stem growth continuity (percentage of ADFs) showed a hump-shaped relationship with elevation reaching a maximum at around 1000 m a.s.l. Low- to mid-elevation tree growth was positively correlated with the Palmer Drought Severity Index (PDSI; indicating aridity) and sea surface temperature (indicating trade wind-influenced moderation of water supply), while high-elevation tree growth was positively correlated with winter temperature (indicating a cold-induced dormancy period). We conclude that ADFs are a useful method to measure stem growth continuity in low-seasonality climates. Growth of P. canariensis on the Canary Islands is more frequently interrupted by winter cold at high elevations and by summer drought at low elevations than in the trade wind-influenced mid elevations, where growth sometimes continues throughout the year. Climate change-associated alterations in trade wind cloud formation might cause non-analogue growth limitations for many unique island species.
Dragonflies from the Cape Verde Islands, collected between 1960 and 1989 and kept in institutes in Portugal and Cape Verde, were studied. The Cape Verde collection at the Centro de Zoologia, Instituto de Investigação Científica Tropical, Lisbon, Portugal, includes eight species of dragonflies represented by 279 specimens collected in 1960-61 and 1969-72. The entomological collection at the Instituto Nacional de Investigação e Desenvolvimento Agrário (INIDA), São Jorge dos Orgãos, Republic of Cape Verde, includes four odonate species, represented by 27 specimens, collected in the years 1987 and 1989. Anax tristis Hagen and A. rutherfordi McLachlan, single male specimens of which were collected in Santo Antão, 27 October 1972, are new taxa for the archipelago. Both are tropical migrants of which the nearest known occurrence in continental Africa is more than 1,000 and 1,500 km, respectively, from the Cape Verde Islands. The two collections contain several specimens from new localities within the archipelago, particularly from the islands of Maio and Fogo. Current knowledge of flight season and island distribution are summarized and updated.
A team of experienced lepidopterists sampled the butterfly fauna of Peru’s Cosñipata Region from 400 to 4,000 m elevation for more than a decade (7,440 field person hours) and supplemented this sample with data from museum specimens and the scientific literature. An annotated checklist of Cosñipata Riodinidae (Lepidoptera: Papilionoidea) documents 398 species, which represents 29% of the world Riodinidae fauna. For each, it lists sample abundance, adult behavior, elevation, and temporal distribution. In the fieldwork sample, 75 species (20.9%) were sampled once and 39 (9.8%) were not encountered (collected or imaged by others). A riodinid species of median abundance was sampled an average of once every 826 field person-hours. Sampled sex ratios were 81.2% male, but were not statistically higher in species in which male perching behavior was observed. We document examples of conspicuous geographic variation in the time of male perching behavior. Species richness is greatest at low elevation and at the transition between the dry and wet seasons. There is little evidence that the community is composed of species restricted to narrow elevational bands or restricted in the adult stage to a single season. Compared with Lycaenidae, Riodinidae are significantly more restricted to lowland habitats and were sampled 2.5 times as frequently with a mean number of individuals per species more than twice as great as that of Lycaenidae.
ZooBank registration. urn:lsid:zoobank.org:pub:51233294-9511-41E4-980F-5A0D9080C680
Peru’s Cosñipata Region in Cuzco and Madre de Dios Departments is a valley between Manu National Park and the Amarakaeri Communal Reserve that ranges from 400 to 4,000 m elevation. A team of experienced lepidopterists sampled the butterfly fauna of this valley for more than a decade (7,440 field person-hours). We analyze the data for Lycaenidae (Lepidoptera: Papilionoidea), a family for which we have taxonomic expertise. After adding data on the fauna from museums and the literature, we present an annotated checklist of the 340 Lycaenidae species recorded from the Cosñipata Region with notes for each species on the elevations and seasons at which it occurs, adult behavior, and sampled relative abundance. Species richness is twice that recorded for Trinidad or Brazil’s Parque Nacional do Itatiaia, each of which also has a mix of low, mid, and high elevation habitats. There was an average of 8.3 adult specimens per species in the fieldwork sample. For those species with more than 8 specimens, the median elevational range was 1,100 m. Species richness in low elevation habitats was greater than that at mid or high elevations, which is contrary to findings for some other Neotropical insects. We present evidence why further sampling is likely to increase this difference. Maximal adult species richness occurs during the transition from dry to wet seasons (September to November) at all elevations, but there is little evidence that adults of species occur only during this season. Sampled relative abundances were skewed so that 70% of the species were encountered less frequently than average (1/340). These results are consistent with the observation that most species are rarely encountered using standard sampling methods.
Nocturnal multi-species roosts of Cicindelidae (Coleoptera) in a Neotropical lowland rainforest
(2021)
Tiger beetles (Coleoptera: Cicindelidae) are frequent predators on the forest floor of the Amazon rainforest. We report on five diurnal sympatric tiger beetle species belonging to the genera Odontocheila Laporte de Castelnau and Poecilochila Rivalier in a terra firme rainforest in South Venezuela. We observed adult beetles for a full year and monitored their nocturnal roosts along two forest paths during the rainy season in 1998. We found up to four species communally roosting on low vegetation along the paths during the night. Multi-species roosts were more often observed than conspecific communal roosts. Although the individual composition of the nocturnal roosts changed frequently, distinct plants were used for several days to weeks. The most individual-rich roosts comprised 10 or 11 adult tiger beetles roosting on one leaf. Observed nocturnal roosts were dominated by O. angulipenis W. Horn and O. margineguttata (Dejean). Most mixed roosts included O. confusa (Dejean), O. angulipenis and O. margineguttata. Low abundances and size differences possibly facilitate the coexistence of these five tiger beetle species. The advantage of communal roosting during the rainy season is probably the reinforcement of their chemical defense.
The arboreal click beetle fauna (Coleoptera: Elateridae) in a lowland tropical rainforest in southern Venezuela was observed and collected by means of a tower crane for a full year. The evaluation of the elaterid assemblage is part of a general survey of Coleoptera associated with several canopy trees. The Elateridae represented the tenth most species-rich beetle family in the canopy of the crane plot and was therefore selected for a detailed analysis of host-use patterns. In total, 20 species of Elateridae with 402 adult individuals were sampled, including seven singletons. Species were either flower visiting (Aeolus Eschscholtz and Cosmesus Candèze) or fed mainly on extrafloral nectaries (Chalcolepidius Eschscholtz, Crepidius Candèze, Lacon Castelnau, Lissomus Dalman, and Semiotus Eschscholtz). The most abundant species was Aeolus sp. 1 (N = 306) feeding on flowers of nine different host-tree species. This species was found often in high abundances during the entire flowering period of a single tree species with highest abundances coinciding with the maximum of open flowers. Aeolus sp. 1 was recorded almost every month of the year moving usually from one flowering tree species to another comprising possibly the entire local population. This species showed preferences between different tree species and occurred there only at night. Tree species that supported the most species-rich elaterid assemblages were Ruizterania trichanthera (Spruce ex Warm.) Marc.-Berti (Vochysiaceae) (N = 8) and Goupia glabra Aubl. (Goupiaceae) (N = 6). Only one elaterid species with at least two collected individuals was found restricted to one tree species.