Heriberto López

Temperature variation and the presence of troglobionts in terrestrial shallow subterranean habitats

Within the soil matrix and underlying rock, cracks and fissures and other air-filled spaces between rocks, sometimes called the milieu souterrain superficiel (MSS), are present in a variety of geological contexts. We examined year-long hourly temperature profiles at sites in lava in the Canary Islands and limestone in Slovenia. All sites had species that show morphological adaptations usually associated with cave-dwelling organisms, including elongated appendages and reduced eyes and pigment. MSS sites were studied at depths between 10 and 70 cm and showed strong seasonality, and most had a discernible diurnal cycle as well. The most striking difference from surface habitats was that the temperature extremes were much less pronounced in MSS sites. Temperature variability was not correlated with troglobiotic species richness. The presence of species with similar morphologies to those found in caves indicates that selective pressures are similar in cave and shallow subterranean habitats.

Delimiting species boundaries for endangered Canary Island grasshoppers based on DNA sequence data

Mitochondrial DNA cytochrome oxidase subunit I and nuclear ITS2 sequences were surveyed from Canary Islands threatened species of the genera Purpuraria and Acrostira (Orthoptera: Pamphagidae). Phylogenetic and population analyses show that the two previously recognized Purpuraria erna subspecies are not valid as conservation units, and that there is a new unrecognized species of Purpuraria, coincident with recently discovered morphological variation within the genus. In addition, mitochondrial introgression seems to occur between the two Purpuraria species in southwest Lanzarote. Species-delimitation based on the morphological taxonomy of Acrostira, which recognizes four single-island endemics, is only partially supported by the genetic data. It shows that currently admitted species from the central and western islands of Tenerife, La Gomera and La Palma are closely related, with evidence of recent gene flow between the Tenerife and La Gomera populations. MtDNA variation also showed that A. euphorbiae, currently considered as the most critically endangered grasshopper species in the Canaries, has lower population diversity than its close relatives.

Habitat use and phenology of the large insular endemic grasshopper Acrostira euphorbiae (Orthoptera: Pamphagidae)

The habitat use and the phenology of the large grasshopper Acrostira euphorbiae García and Oromí endemic to La Palma (Canary Islands) are studied. This grasshopper is entirely dependent on the Canarian endemic shrub Euphorbia lamarckii both for food and to avoid predation. Adults stay on subapical branches during the day, probably to reduce the risk of predation, and climb up to the apex at night to feed. While females seem to ensure the genetic diversity of offspring by waiting for visits by different males, the latter have to move to guarantee their reproductive success. Monophagy in this species may be related to the year-round presence of tender shoots, and to the predator-repellent toxic latex found in the host plant. Unlike related species from continental areas, adults and nymphs of A. euphorbiae are present almost all year round, probably in adaptation to the particular climate of the islands. Nymphs are more abundant in winter, when Euphorbia leaves are most available. However, adults are more abundant than nymphs in spring, summer and autumn. Males develop more quickly than females, an apparent reproductive strategy based on achieving sexual maturity to coincide with females undergoing imaginal moulting. Matings start immediately after adult females emerge. Densities oscillated between 73 and 193 individuals ha(-1), which can be considered a low value compared with other continental pamphagid species.

Microsatellite loci development in endangered pamphagid grasshoppers endemic to the Canary Islands (Orthoptera)

The five recognized endemic pamphagid species (Orthoptera) of the Canary Islands have restricted and fragmented ranges due to habitat decline. Seven polymorphic microsatellite markers have been developed for Acrostira tamarani, and the performance of primer pairs amplifying these loci in related taxa has been tested. The number of alleles in A. tamarani samples taken from two distant localities in the island of Gran Canaria ranged from two to eight per locus. Observed heterozygosities were from 0.151 to 0.559. Up to four primer pairs amplified in related species with moderate heterozigosities (maximum of 0.687 and 10 alleles for Ata67 locus in Purpuraria erna). These markers could be useful tools to study the population structure and management of endemic threatened pamphagids of the Canary archipelago.

Trophic strategies of Yellow-legged Gull Larus michahellis on oceanic islands surrounded by deep waters

ABSTRACT Capsule: The diet of Yellow-legged Gulls Larus michahellis on an oceanic island, surrounded by deep waters without a wide shelf, was mainly composed of terrestrial invertebrates. Aims: To study the trophic ecology of Yellow-legged Gulls on an island surrounded by deep waters, to quantify the importance of terrestrial prey items and their availability, and to evaluate the relative importance of nutritional values of terrestrial and marine resources. Methods: Diet was monitored for one year. We assessed the relative contribution of the main prey items and their macronutrients through the study of pellets and faeces. Results: Terrestrial invertebrates were the most frequently consumed prey items (frequency of occurrence (FO) 67%), followed by marine fish (Osteichthyes FO 33%). Coleoptera and Orthoptera were the most consumed terrestrial invertebrates and provided a high nutritional value. The rate of consumption of terrestrial invertebrates varied in synchrony with the breeding season, being higher in spring, indicating their potential importance for reproduction. Conclusion: It is unusual that terrestrial invertebrates constitute a large proportion of the diet of large gulls, but they seemed to cover their trophic energy requirements during the reproductive period.

A new species of Oromia (Coleoptera: Curculionidae) from the Canary Islands

The weevil Oromia thoracica n. sp. from Gran Canaria (Canary Islands) is described and compared to its closest allies. It can easily be distinguished by less sculptured elytra, its differently shaped antennal scrobe, and by the pronotum not constricted anteriorly and expanded over the head. Some ecological data are also provided, and considerations on the fauna occurring in the mesovoid shallow substratum (MSS) from the locality of this new species are made. Additional records and comments on other Oromia species as well as an identification key to the species of the genus are given.

Endemism and evolution in the littoral woodlouse Halophiloscia Verhoeff, 1908 (Crustacea, Isopoda, Oniscidea) from the Canary Islands: implications for conservation policies

The woodlouse genus Halophiloscia Verhoeff, 1908 includes littoral halophilous species distributed along the coasts of the Mediterranean Sea, the Atlantic coasts of Europe and northern Africa. The species Halophiloscia couchii has been introduced to the Americas, Hawaii and Australia. The Canary Islands harbour four species, two of which are included in catalogues of endangered species. One mitochondrial and one nuclear gene sequenced from over 100 specimens, including outgroups, were analysed to infer the colonisation and diversification processes of Halophiloscia in the Canary Islands and shed light on their conservation status. The Canary Islands were independently colonised by three distinct Halophiloscia lineages: (i) the endemic species H. rodriguezi, collected in several western Canary Islands, and the troglobiomorphic H. microphthalma from La Palma, (ii) the endemic H. canariensis, found throughout the eastern Canaries, and (iii) the cosmopolitan H. couchii, present on Gran Canaria and Tenerife. Halophiloscia microphthalma is not sister to the extant epigean Halophiloscia species present on the same island, which together with the low levels of genetic variability detected in the species may warrant a higher conservation status than presently given. The mitochondrial marker revealed a fine‐scale phylogeographic structure in H. canariensis, and rejected recent sharp declines in its population size, which in addition to its widespread distribution challenge its consideration as an endangered species. The presence of H. couchii in the archipelago is interpreted as a recent introduction. Although no evidence of introgression was detected, more thorough sampling and monitoring of introduced populations are recommended to discard either hybridisation or competitive displacement of native species.

Figure 1 In A New Species Of Oromia (Coleoptera: Curculionidae) From The Canary Islands

FIGURE 1. Habitus of Oromia thoracica n. sp. (female). A: dorsal view. B: ventral view. C: lateral view.