Phylogeny of the tribe Indigofereae (Leguminosae-Papilionoideae): Geographically structured more in succulent-rich and temperate settings than in grass-rich environments

This analysis goes beyond many phylogenies in exploring how phylogenetic structure imposed by morphology, ecology, and geography reveals useful evolutionary data. A comprehensive range of such diversity is evaluated within tribe Indigofereae and outgroups from sister tribes. A combined data set of 321 taxa (over one-third of the tribe) by 80 morphological characters, 833 aligned nuclear ribosomal ITS/5.8S sites, and an indel data set of 33 characters was subjected to parsimony analysis. Notable results include the Madagascan dry forest Disynstemon resolved as sister to tribe Indigofereae, and all species of the large genus Indigofera comprise just four main clades, each diagnosable by morphological synapomorphies and ecological and geographical predilections. These results suggest niche conservation (ecology) and dispersal limitation (geography) are important processes rendering signature shapes to the Indigofereae phylogeny in different biomes. Clades confined to temperate and succulent-rich biomes are more dispersal limited and have more geographical phylogenetic structure than those inhabiting tropical grass-rich vegetation. The African arid corridor, particularly the Namib center of endemism, harbors many of the oldest Indigofera lineages. A rates analysis of nucleotide substitutions confirms that the ages of the oldest crown clades are mostly younger than 16 Ma, implicating dispersal in explaining the worldwide distribution of the tribe.     

Eight new species and a new record of Indigofera and Microcharis (Leguminosae-Indigofereae) from Somalia

The following new species are described: Indigofera bayensis (south-west Somalia, on sand or gravel in Acacia-Commiphora bushland), I. gypsacea (central and south-west Somalia, on gypsum), I. karkarensis (north-east Somalia, on limestone), I. lamellata (south-west Somalia, on and around granitic outcrops), I. lughensis (south-west Somalia, on gypsum), I. phymatodea (south-west Somalia, on granitic outcrops), I. scopiformis (central Somalia, on sand in Acacia-Commiphora bushland), and Microcharis nematophylla (central Somalia, on sand in Acacia-Commiphora bushland). Indigofera pseudointricata , previously known only from Socotra, is reported also from Somalia.     

A phylogenetic study of Echidnopsis Hook. f. (Apocynaceae-Asclepiadoideae) - taxonomic implications and the colonization of the Socotran archipelago

We investigated the phylogeny, taxonomy and biogeography of the Eritreo-Arabian genus Echidnopsis Hook. f. (Apocynaceae-Asclepiadoideae). Phylogenetic reconstructions based on nrITS sequence data were obtained using maximum likelihood and parsimony analyses. The results reveal two weakly supported clades, each with a mix of African and Arabian taxa, including the genus Rhytidocaulon, and with four Socotran species forming a subclade of their own. Rather than a vicariance origin of these island elements, our data suggest a single dispersal event from eastern Africa. Echidnopsis thus parallels biogeographic patterns found for other Socotran endemic plants. Our revised taxonomy recognizes 28 species and 4 subspecies in the genus. Two new combinations, E. planiflora subsp. chrysantha and E. sharpei subsp. bavazzani are proposed.     

Multiple colonization of Madagascar and Socotra by colubrid snakes: evidence from nuclear and mitochondrial gene phylogenies

Colubrid snakes form a speciose group of unclarified phylogeny. Their almost cosmopolitan distribution could be interpreted as a product of plate-tectonic vicariance. We used sequences of the nuclear c-mos, the mitochondrial cytochrome b and the 16S rRNA genes in 41 taxa to elucidate the relationships between the endemic colubrid genera found in Madagascar and in the Socotra archipelago. The well-resolved trees indicate multiple origins of both the Malagasy and the Socotran taxa. The Malagasy genus Mimophis was nested within the Psammophiinae, and the Socotran Hemerophis was closely related to Old World representatives of the former genus Coluber. The remaining 14 genera of Malagasy colubrids formed a monophyletic sister group of the Socotran Ditypophis (together forming the Pseudoxyrhophiinae). Molecular-clock estimates place the divergence of Malagasy and Socotran colubrids from their non-insular sister groups into a time-frame between the Eocene and Miocene. Over-seas rafting is the most likely hypothesis for the origin of at least the Malagasy taxa. The discovery of a large monophyletic clade of colubrids endemic to Madagascar indicates a need for taxonomic changes. The relationship of this radiation to the Socotran Ditypophis highlights the potential of the Indian Ocean islands to act as an evolutionary reservoir for lineages that have become extinct in Africa and Asia.     

New or noteworthy species of Leguminosae in NE tropical Africa

The following new species are described: Chamaecrista dunensis (Somalia), Acacia densispina (Somalia), A. flagellaris (Somalia), Tephrosia karkarensis (Somalia), T. scopulata (Somalia), Indigofera ancistrocarpa (Kenya), I. curvirostrata (Ethiopia), I. hiranensis (Somalia), I. karinensis (Somalia), I. kucharii (Somalia), I. nugalensis (Somalia), I. pellucida (Kenya, Somalia), I. sabulosa (Ethiopia, Somalia), I. sessilis (Somalia), I. ienuirostris (Somalia), Rhynchosia megalocalyx (Somalia), Crotalaria allophylla (Somalia), C. intricata (Somalia), C. warfae (Somalia), and Coronilla somalensis (Somalia). 2n = 22 is reported in Tephrosia karkarensis. Cassia somalensis, Acacia puccioniana, Sophora somalensis , and Crotalaria sennii are reduced to synonyms of respectively Senna hookeriana, Dichrostachys kirkii, Millettia usaramensis and Crotalaria boranica subsp. trichocarpa . Thirty-seven taxa are reported from Somalia for the first time, including Ptycholobium biflorum , known previously only from Southern Africa. Crotalaria pieropoda , known previously only from Socotra, is reported from Somalia and Oman. Neptunia oleracea and Vatovaea pseudolablab are new generic records for respectively Ethiopia and Oman. The fruits of Indigofera boranica are described. Vigna somaliensis and an allied species are discussed. Rhynchosia gansole is lectotypified and its flowers and fruits are described.     

Structure and evolution of the pod in Indigofera (Fabaceae) reveals a trend towards small thin indehiscent pods

Pod morphology and anatomy have been studied in 28 species and four varieties of Indian Indigofera. Pods of Indigofera spp. differ with respect to size, the relative thickness of the fruit wall, the number of sclerenchymatous layers in the endocarp, the presence/absence of hypodermis and trichomes, and the presence of separation tissue. Anatomically, the pericarp is broadly characterized into three types: type I (thin pericarp and three to five sclerenchymatous layers in the endocarp), type II (intermediary pericarp thickness and six to eight sclerenchymatous layers), and type III (thick pericarp and more than eight sclerenchymatous layers). The distribution of these types across the tribe is not congruent with the current phylogenetic analyses. Type III pericarp (present in the early diverging lineages of the tribe) represents the most primitive state, whereas type I and type II pericarps are derived. Fruits of Indigofera generally show normal explosive dehiscence as a means of dispersal of seeds, although some species show adaptations for dispersal by wind. In Indigofera, dehiscence is caused by a separation layer present at the dorsal and ventral sutures except in some species (Indigofera hochstetteri, Indigofera karnatakana, Indigofera glandulosa var. sykesii, and Indigofera trita var. scabra) in which no separation tissue is present; these species show delayed dehiscence or an indehiscent condition. The indehiscent pod type is considered to be apomorphic. The taxonomic, functional, and evolutionary significance of morphological and anatomical features in fruits of the genus Indigofera has been evaluated. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 176 , 260–276.     

A reappraisal of the systematic affinities of Socotran,Arabian and East African scops owls (Otus,Strigidae) using a combination of molecular,biometric and acoustic data

We investigated phylogenetic relationships among Otus scops owls from Socotra Island, the Arabian Peninsula and East Africa using molecular, vocalization and biometric data. The Socotra Scops Owl Otus senegalensis socotranus, currently treated as a subspecies of the African Scops Owl Otus senegalensis, is more closely related to the Oriental Scops Owl Otus sunia and to the endemic Seychelles Scops Owl Otus insularis. Considerable mitochondrial genetic distance and significant morphological differentiation from its two closest relatives, as well as its distinctive vocalizations compared with O. insularis, strongly support recognition of Socotra Scops Owl as a full species. Unexpectedly, two taxa from the Arabian Peninsula, Pallid Scops Owl Otus brucei and African Scops Owl Otus senegalensis pamelae, represent very distinct lineages; O. brucei is basal to a clade that includes taxa found in the Indo‐Malayan region and on Indian Ocean islands. In contrast, O. s. pamelae occupies a well‐supported basal position within a clade of continental Afro‐Palaearctic taxa. The uncorrected‐p genetic distance between O. s. pamelae and its closest relatives (other populations of senegalensis from mainland Africa) is c. 4%. As O. s. pamelae is also well differentiated phylogenetically, morphologically and vocally from O. s. senegalensis, we recommend its elevation to species status, as Otus pamelae. Among mainland African O. senegalensis subspecies, Ethiopian populations appear to represent the most divergent lineage, whereas other lineages from Somalia, Kenya and South Africa are poorly differentiated. The large genetic distance between the Ethiopian haplotype and other African haplotypes (3.2%) suggests that the Ethiopian Otus may represent a cryptic taxon, and we recommend that more individuals be sampled to assess the taxonomic status of this population.     

Reconstructing an island radiation using ancient and recent DNA: the extinct and living day geckos (Phelsuma) of the Mascarene islands

Mitochondrial (12SrRNA and cyt b, 1086 bp) and nuclear (c-mos, 374 bp) DNA sequences were used to investigate relationships and biogeography of 24 living and extinct taxa of Phelsuma geckos. Monophyly of Phelsuma and sister relationship to the SW African Rhoptropella is corroborated. Phelsuma originated on Madagascar and made multiple long-distance invasions of oceanic islands including the Mascarenes, Aldabra, Comores, Seychelles, Andamans, and perhaps Pemba. The Mascarenes were probably colonised once, about 4.2-5.1Ma, and here Phelsuma rosagularis and Phelsuma inexpectata are newly recognised as species, as are three lineages of Phelsuma cepediana. Mascarene relationships are: Phelsuma edwardnewtoni, Phelsuma gigas (Phelsuma guentheri ((((P. cepediana A (P. cepediana B, C)) P. rosagularis) Phelsuma borbonica) ((Phelsuma ornata, P. inexpectata) Phelsuma guimbeaui))). The two recently extinct species, P. edwardnewtoni and the giant secondarily nocturnal Phelsuma gigas, differentiated on Rodrigues while on Mauritius the large nocturnal P. guentheri separated from a small diurnal form that radiated into six species, a likely result of volcanic activity. Two small-bodied lineages from Mauritius invaded the more recent island of Réunion producing two more species. Outside the Mascarenes, two mainly Madagascan assemblages are substantiated: Phelsuma serraticauda (Phelsuma lineata, Phelsuma laticauda, Phelsuma quadriocellata); (Phelsuma m. kochi (Phelsuma m. grandis, Phelsuma abboti)) (Phelsuma astriata, Phelsuma sundbergi). Their relationships to the Mascarene clade, and to Phelsuma mutabilis, Phelsuma standingi and Phelsuma andamanensis are unresolved.     

New and noteworthy species of Indigofera (Leguminosae) from NE Africa

Six new species of Indigofera are described: I. eremophila Thulin from E Ethiopia, I. mooneyi Thulin from the highlands of SW Ethiopia, I. boranica Thulin from SE Ethiopia and NE Kenya, I. gyrata Thulin and I. ammophila Thulin from NE Kenya, and I. cana Thulin from north–central Ethiopia. I. cavallii Chiov., previously known only from the type from S Somalia, is reported also from NE Kenya.     

Trans-oceanic dispersal and evolution of early composites (Asteraceae)

How did Asteraceae (the daisy family) expand from its area of origin and become so widespread? This question has challenged generations of evolutionary botanists. Molecular phylogenetic and biogeographic analyses indicate a South American origin of Asteraceae, a view supported by the recent discovery of the earliest fossils of the family in Middle Eocene (ca. 50 Ma) deposits in southern South America. The early-branching lineages in the phylogenetic tree of Asteraceae are South American and African, suggesting that the earliest successful colonization of areas outside South America may have involved long-distance dispersal to Africa. However, one particularly challenging unanswered question is how early members of Asteraceae reached Africa at a time when the Atlantic Ocean constituted a barrier between the two continents. Morphological, phylogenetic, geographic, paleogeographic, and paleontologic data have been combined to propose scenarios on possible geographical and dispersal routes and vectors of dispersion of early-branching lineages of Asteraceae from South America to Africa. Of the different scenarios proposed here, two concern alternative geographical routes: (1) via the Rio Grande Rise-Walvis Ridge axis in the South Atlantic; or (2) via Antarctica, possibly including the Subantarctic islands. Three scenarios consider different dispersal routes: (1) stepping-stones; (2) single-step; and (3) sweepstakes. Finally, three vectors of dispersion are considered: (1) birds; (2) wind; and (3) floating islands. Evaluation of these scenarios suggests that early-branching lineages of Asteraceae probably dispersed from South America to Africa along an island chain formed by the Rio Grande Rise and the Walvis Ridge, transported by birds, possibly combined with rafting and/or sweepstakes. Morphological changes typically associated with evolution on islands characterize many African carduoid descendants, providing indirect evidence for step-wise dispersal along the island chain.     

Y-chromosome lineages in Cabo Verde Islands witness the diverse geographic origin of its first male settlers

The Y-chromosome haplogroup composition of the population of the Cabo Verde Archipelago was profiled by using 32 single-nucleotide polymorphism markers and compared with potential source populations from Iberia, west Africa, and the Middle East. According to the traditional view, the major proportion of the founding population of Cabo Verde was of west African ancestry with the addition of a minor fraction of male colonizers from Europe. Unexpectedly, more than half of the paternal lineages (53.5%) of Cabo Verdeans clustered in haplogroups I, J, K, and R1, which are characteristic of populations of Europe and the Middle East, while being absent in the probable west African source population of Guiné-Bissau. Moreover, a high frequency of J* lineages in Cabo Verdeans relates them more closely to populations of the Middle East and probably provides the first genetic evidence of the legacy of the Jews. In addition, the considerable proportion (20.5%) of E3b(xM81) lineages indicates a possible gene flow from the Middle East or northeast Africa, which, at least partly, could be ascribed to the Sephardic Jews. In contrast to the predominance of west African mitochondrial DNA haplotypes in their maternal gene pool, the major west African Y-chromosome lineage E3a was observed only at a frequency of 15.9%. Overall, these results indicate that gene flow from multiple sources and various sex-specific patterns have been important in the formation of the genomic diversity in the Cabo Verde islands.An erratum to this article can be found at     

Mitochondrial DNA patterns in the Macaronesia islands: Variation within and among archipelagos

Macaronesia covers four Atlantic archipelagos: the Azores, Madeira, the Canary Islands, and the Cape Verde islands. When discovered by Europeans in the 15th century, only the Canaries were inhabited. Historical reports highlight the impact of Iberians on settlement in Macaronesia. Although important differences in their settlement are documented, its influence on their genetic structures and relationships has yet to be ascertained. In this study, the hypervariable region I (HVRI) sequence and coding region polymorphisms of mitochondrial DNA (mtDNA) in 623 individuals from the Azores (120) and Canary Islands (503) were analyzed. Combined with published data, these give a total of 1,542 haplotypes from Macaronesia and 1,067 from the Iberian Peninsula. The results obtained indicate that Cape Verde is the most distinctive archipelago, with an mtDNA pool composed almost exclusively of African lineages. However, the other archipelagos present an mtDNA profile dominated by the presence of West‐Eurasian mtDNA haplogroups with African lineages present in varying proportions. Moreover, no signs of integration of typical Canarian U6 lineages in the other archipelagos were detected. The four Macaronesia archipelagos currently have differentiated genetic profiles, and the Azores present the highest intra‐archipelago differentiation and the lowest values of diversity. The analyses performed show that the present‐day genetic profile of the Macaronesian archipelagos was mainly determined by the initial process of settlement and further microdifferentiation probably as a consequence of the small population size of some islands. Moreover, contacts between archipelagos seem to have had a low impact on the mtDNA genetic pool of each archipelago. Am J Phys Anthropol, 2010. © 2009 Wiley‐Liss, Inc.     

Intraspecific phylogeography in the sedge frog Litoria fallax (Hylidae) indicates pre-Pleistocene vicariance of an open forest species from eastern Australia

The eastern sedge frog Litoria fallax (Anura: Hylidae) is common throughout the open forests and coastal wetlands along the eastern coast of Australia. Its range spans four biogeographical zones from northern Queensland to central New South Wales. Phylogenetic analysis of mitochondrial DNA (mtDNA) haplotypes of 87 L. fallax individuals from 22 populations identified two major mtDNA lineages, differing by 11-12% sequence divergence. The two clades of haplotypes were separated by the McPherson Range, indicating that this mesic upland area has acted as a major long-term barrier to gene flow for this open forest species. Slight isolation by distance was observed within both the northern and southern lineages but was insufficient to explain the large sequence divergence between lineages. Within the northern lineage, additional phylogeographical structure was observed across the relatively dry Burdekin Gap which separates Atherton populations from all populations in the central and eastern Queensland biogeographical zones. There was less phylogeographical structure in the southern lineage suggesting historical gene flow across the drier portions of the Great Dividing Range. These data, together with recent observations of deep phylogeographical divergences in rainforest-restricted Litoria suggest that the east coast hylids of Australia represent an old (Tertiary) radiation. Individual species of Litoria have been strongly affected by climatic and ecological barriers to gene flow during the Quaternary.     

Molecular phylogeny and biogeography of West Indian frogs of the genus Leptodactylus (Anura, Leptodactylidae)

Three endemic species of the aquatic-breeding frog genus Leptodactylus are recognized from the West Indies: Leptodactylus albilabris (Puerto Rico and the Virgin Islands), Leptodactylus dominicensis (Hispaniola), and Leptodactylus fallax (Lesser Antilles). DNA sequences were obtained from several mitochondrial genes to resolve taxonomic questions involving these species and to provide insights into their origin and distribution in the islands. We found low levels of sequence divergence between L. dominicensis and L. albilabris, supporting morphological evidence that the former species is a junior synonym of the latter species. Phylogenetic analysis supported previous species-group allocations, finding that L. albilabris is a member of the fuscus group and L. fallax is a member of the pentadactylus group. Molecular time estimates for the divergence of L. albilabris from its closest relative in South America (24-58 million years ago, Ma) and for L. fallax from its closest relative in South America (23-34Ma) indicate that they colonized the West Indies independently by over-water dispersal in the mid-Cenozoic. The absence of detectable sequence divergence between the two extant populations of L. fallax (Dominica and Montserrat), a species used for human food and now critically endangered, suggests that one or both arose by human introduction from an island or islands where that species originated. The relatively minor genetic differentiation of populations of L. albilabris can be explained by vicariance and dispersal in the Pleistocene and Holocene, although human introduction of some populations cannot be ruled out.     

Colonisation and Diversification of the Zenaida Dove (Zenaida aurita) in the Antilles: Phylogeography,Contemporary Gene Flow and Morphological Divergence

Caribbean avifaunal biogeography has been mainly studied based on mitochondrial DNA. Here, we investigated both past and recent island differentiation and micro-evolutionary changes in the Zenaida Dove (Zenaida aurita) based on combined information from one mitochondrial (Cytochrome c Oxydase subunit I, COI) and 13 microsatellite markers and four morphological characters. This Caribbean endemic and abundant species has a large distribution, and two subspecies are supposed to occur: Z. a. zenaida in the Greater Antilles (GA) and Z. a. aurita in the Lesser Antilles (LA). Doves were sampled on two GA islands (Puerto Rico and the British Virgin Islands) and six LA islands (Saint Barthélemy, Guadeloupe, Les Saintes, Martinique, Saint Lucia and Barbados). Eleven COI haplotypes were observed that could be assembled in two distinct lineages, with six specific to GA, four to LA, the remaining one occurring in all islands. However, the level of divergence between those two lineages was too moderate to fully corroborate the existence of two subspecies. Colonisation of the studied islands appeared to be a recent process. However, both phenotypic and microsatellite data suggest that differentiation is already under way between all of them, partly associated with the existence of limited gene flow. No isolation by distance was observed. Differentiation for morphological traits was more pronounced than for neutral markers. These results suggest that despite recent colonisation, genetic drift and/or restricted gene flow are promoting differentiation for neutral markers. Variation in selective pressures between islands may explain the observed phenotypic differentiation.     

Integrative taxonomy in two free-living nematode species complexes

Integrative taxonomy considers species boundaries from multiple, complementary perspectives, with the main objective being to compare the observed data against the predictions of the methodologies used. In the present study we used three methods for delineating species boundaries within the cosmopolitan nematode species Rhabditis ( Pellioditis ) marina and Halomonhystera disjuncta . First, phylogenetic relationships among molecular sequences from the mitochondrial cytochrome oxidase c subunit 1 gene (COI), and from two nuclear regions, internal transcribed spacer (ITS) and D2D3, were analysed. Subsequently, multivariate morphometric analysis was used to investigate whether concordant molecular lineages were also morphologically distinct. When morphological differences were found, typological taxonomy was performed to identify fixed or non-overlapping characters between lineages. Interbreeding experiments were conducted between the two closest related lineages of R . ( P. ) marina to investigate potential reproductive isolation. This integrative approach confirmed the presence of several species within each nominal species: molecular lineages were concordant across two independent loci (COI and ITS), and were characterized by significant morphological divergence. Most lineages were also detectable in the D2D3 region, but were less resolved. The two lineages investigated in our study did not produce offspring. Our results highlight that classical taxonomy grossly underestimates species diversity within the phylum Nematoda.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 737–753.     

Interspecific differentiation and intraspecific substructure in two closely related clupeids with extensive hybridization, Alosa alosa and Alosa fallax

In this study, the evolutionary relationships within and among populations of European shads, Alosa alosa and Alosa fallax , was investigated. Screening of allelic variation across eight allozyme loci and sequencing 448 bp of the mtDNA cytochrome b gene in 14 rivers throughout the range of the species supported that the two taxa were independent lineages (1·3% net nucleotide divergence) despite extensive hybridization. Genetic diversity and structure was considerably higher in A. fallax than A. alosa and the former species revealed evidence of distinct lineages in the Mediterranean and Atlantic basins. A Bayesian clustering approach combined with gill raker counts verified that individuals of the two species could be assigned to their parent group with relatively high confidence. Evaluation of hybridization in the Lima and Mondego Rivers in Portugal provided evidence that introgression is extensive but is not currently obscuring (through hybrid swarming) the diagnosability of the two species.     

Connectivity,small islands and large distances: the Cellana strigilis limpet complex in the Southern Ocean

The Southern Ocean contains some of the most isolated islands on Earth, and fundamental questions remain regarding their colonization and the connectivity of their coastal biotas. Here, we conduct a genetic investigation into the Cellana strigilis (limpet) complex that was originally classified based on morphological characters into six subspecies, five of which are endemic to the New Zealand (NZ) subantarctic and Chatham islands (44–52°S). Previous genetic analyses of C. strigilis from six of the seven island groups revealed two lineages with little or no within‐lineage variation. We analysed C. strigilis samples from all seven island groups using two mitochondrial (COI and 16S), one nuclear (ATPase β) and 58 loci from four randomly amplified polymorphic DNA markers (RAPDs) and confirmed the existence of two distinct lineages. The pronounced genetic structuring within each lineage and the presence of private haplotypes in individual islands are the result of little genetic connectivity and therefore very high self‐recruitment. This study supports the significance of the subantarctic islands as refugia during the last glacial maximum and adds to the knowledge of contemporary population connectivity among coastal populations of remote islands in large oceans and the distance barrier to gene flow that exists in the sea (despite its continuous medium) for most taxa.     

梣属药用植物的分类研究

本文报道我国梣属供药用的9种及3变种植物的分类研究,对本属植物的若干错误鉴定和学名混乱进行了必要的整理修订,提出了1个新变种、2个新等级、3个新异名,为本属药用植物的准确鉴定和系统分类研究提供了一定的依据。     

Living on the edge: demographic and phylogeographical patterns in the woodlouse-hunter spider Dysdera lancerotensis Simon, 1907 on the eastern volcanic ridge of the Canary Islands

The Eastern Canary Islands are the emerged tips of a continuous volcanic ridge running parallel to the northeastern African coast, originated by episodic volcanic eruptions that can be traced back to the Miocene and that, following a major period of quiescence and erosion, continued from the Pliocene to the present day. The islands have been periodically connected by eustatic sea-level changes resulting from Pleistocene glacial cycles. The ground-dwelling spider Dysdera lancerotensis Simon, 1907 occurs along the entire ridge, except on recent barren lavas and sand dunes, and is therefore an ideal model for studying the effect of episodic geological processes on terrestrial organisms. Nested clade and population genetic analyses using 39 haplotypes from 605 base pairs of mitochondrial DNA cytochrome c oxidase I sequence data, along with phylogenetic analyses including two additional mitochondrial genes, uncover complex phylogeographical and demographic patterns. Our results indicate that D. lancerotensis colonized the ridge from north to south, in contrast to what had been expected given the SSW-NNE trend of volcanism and to what had been reported for other terrestrial arthropods. The occurrence of several episodes of extinction, recolonization and expansion are hypothesized for this species, and areas that act as refugia during volcanic cycles are identified. Relaxed molecular clock methods reveal divergence times between main haplotype lineages that suggest an older origin of the northern islets than anticipated based on geological evidence. This study supports the key role of volcanism in shaping the distribution of terrestrial organisms on oceanic islands and generates phylogeographical predictions that warrant further research into other terrestrial endemisms of this fascinating region.