A fossil Halobates from the Mediterranean and the origin of sea skaters (Hemiptera, Gerridae)

Five species of sea skaters, genus Halobates Eschscholtz, are the only insects to have successfully colonized the open ocean. In addition, 38 species are found in sheltered coastal waters throughout tropical Indo-Pacific. The taxonomy of the genus is relatively well known, and the phylogeneuc relationships between extant species have recently been analysed (using cladistic methods). In the present paper, we describe the first fossil species of sea skaters, Halobates ruffoi sp. no v. from the Eocene deposit 'Pesciara di Bolca', in the province of Verona, northeastern Italy (geological age about 45 Myr). The significance of this fossil in setting the time scale for the reconstructed phylogeny and anagenesis of adaptive features of sea skaters, and in understanding the evolution and historical zoogeography of these marine insects is discussed.     

The sea-skater Halobates (Heteroptera: Gerridae) – probable cause for extinction in the Mediterranean and potential for re-colonisation following climate change

Sea-skaters in the genus Halobates Eschscholtz 1822 include some of the most specialised water striders and are found in tropical and subtropical seas around the world. Even though species of Halobates occur in both the Atlantic Ocean and the Red Sea, no extant sea-skater has been reported from the Mediterranean Sea. A fossil, Halobates ruffoi Andersen et al., 1994, described from Middle–Upper Eocene (45 Ma) Italy indicates that sea skaters were present in this part of the world in the past. Other geological evidence points to dramatic changes in the Mediterranean Sea during the Tertiary and Quaternary that may have led to their later extinction. In this paper we review briefly the distribution, systematics, evolution and ecology of Halobates, and discuss the potential for the Mediterranean to be recolonised following expected environmental changes due to global warming.     

The phylogeny of Halgerda (Opisthobranchia, Nudibranchia) with the description of a new species from Okinawa

This paper proposes a refined hypothesis of evolution for the tropical Indo-Pacific nudibranch genus Halgerda . Numerous specimens from 31 species were examined anatomically and literature from four additional species was reviewed, bringing to 33 the ingroup taxa. Fifty-three characters were considered from these examinations. The outgroup Asteronotus was used to polarize the characters. The phylogeny obtained from the analysis of the characters supports the hypothesis that Halgerda is a monophyletic group. A species previously placed with the genus Sclerodoris is examined and determined to be a member of the genus Halgerda . Phylogenetic analysis places this species, H. paliensis , as a basal member of the genus . Halgerda paliensis appears to be restricted to the Hawaiian Islands. Specimens previously identified as Sclerodoris paliensis from the Marshall Islands actually represent H. dalanghita Fahey & Gosliner, 1999. A new species, Halgerda onna , is described and presented as the sister taxon to a basal member of the genus. A range and depth extension of a previously described species, H. malesso , is presented. The present phylogeny is then compared to previous studies, in particular those of Fahey & Gosliner (1999a,b) .     

Relationships within the family Actiniidae (Cnidaria,Actiniaria) based on molecular characters

Current sea anemone systematics is based on relatively few morphological characters, and potentially could benefit from the use of molecular characters. In this paper, the phylogenetic relationships of 12 species from 6 genera in the family Actiniidae have been investigated using electrophoretically separated isozymes. A numerical cladistic analysis has produced an estimated phylogeny. The implications of this phylogeny for the taxonomic use of certain morphological characters are discussed.     

Description of a new species and phylogenetic analysis of the subtribe Cynopoecilina,including continuous characters without discretization (Cyprinodontiformes: Rivulidae)

A new species of the subtribe Cynopoecilina is described from the rio Gravataí basin, laguna dos Patos system, southern Brazil. The relationships of the new species among taxa of the subtribe Cynopoecilina is discussed based on two analyses: one using 71 discrete characters and other with the addition of six continuous characters analyzed without discretization. The addition of the continuous characters resulted in the first fully resolved phylogenies for Cynopoecilus and Leptolebias species, not obtained in the analysis including only discrete characters. The new species is assigned to Cynopoecilus as sister group to the remaining species of the genus. A new diagnosis is proposed for Cynopoecilus to accommodate the new species. The resulting phylogeny indicates that the occupation of the grasslands of the Pampa biome by the species of Cynopoecilus occurred along the evolution of the genus and that this event was significant for the diversification of the genus. © 2014 The Linnean Society of London     

Phylogeny of sea skaters, Halobates Eschscholtz (Hemiptera, Gerridae), based on mtDNA sequence and morphology

We examined phylogenetic relationships among halobatine water striders (Hemiptera, Gerridae) using molecular and morphological data. The molecular data set was 780 bp DNA sequence data from the 3' half of the mitochondria! gene encoding cytochrome oxidase subunit I from 19 species of sea skaters, Halobates , and one species from each of three related genera, Asclepios annandalei, Austrobates rivularis , and Eurymetra natalensis. The morphological data set was a slightly modified version of a previously published data set. Unweighted parsimony analyses of the molecular data set gave one tree with weak support for most branches. Maximum likelihood analysis of the same data set gave a tree with slightly different topology, but reveiled many of the clades found in parsimony analyses of the morphological data set. Parsimony analyses of the combined molecular + morphology data sets gave a better resolved and better supported tree than did analyses of any single data set. The phytogeny of Halobates presented here allows a more rigorous evaluation of several prior hypotheses about evolutionary processes in marine water striders. In particular, it supports the hypothesis of at least two separate transitions from coastal to oceanic environments.     

Evolutionary processes in the genus Coreocarpus: insights from molecular phylogenetics

A molecular phylogenetic study of the plant genus Coreocarpus was conducted using nuclear (ITS) and plastid (rpl16 intron) DNA sequences, with phylogenies of the nuclear and plastid sequences highly congruent in defining a monophyletic group of six species (core Coreocarpus), although three other species often placed within the genus were excluded. Relationships within the genus are largely but not totally concordant with prior biosystematic studies. Despite strong molecular support, no morphological characters uniting the six species of core Coreocarpus have been identified; retention of plesiomorphic characters and the genetic lability of characters are two probable factors contributing to lack of consistent defining characters. The age of the core Coreocarpus is estimated at 1 million years because the basal species is endemic to a volcanic island that emerged in the past million years. Mapping the results of earlier breeding studies on the molecular phylogeny showed that use of cross-compatibility as a criterion for species delimitation would result in the recognition of paraphyletic species. Prior field, morphological, and biosystematic studies provided no indication of past hybridization in the evolution of Coreocarpus, and species in the genus appeared to be well defined morphologically. However, three instances of incongruence were observed. Two of these were between the nuclear and plastid partitions, and the third was between the morphological species assignment of one accession and the molecular data. If hybridization accounts for incongruence between the nuclear and plastid data, it occurred between species that now appear to be cross-incompatible and allopatric. The incongruence between morphological species assignment and the molecular data could be the result of parallel fixation of characters that have a simple genetic basis. This study suggests that the evolutionary history of Coreocarpus is much more complex than indicated from prior biosystematic investigations and that biosystematic and molecular phylogenetic studies may complement each other for elucidating the evolution and phylogeny of a group.     

Phylogeny of the radula-less dorids (Mollusca, Nudibranchia), with the description of a new genus and a new family

This paper studies the phylogenetic relationships of the nudibranch dorids that lack a radula. Numerous specimens belonging to 29 different species, representing all genera of this group and other related taxa, were examined anatomically. Details of the foregut were examined with SEM. From this anatomical study a total of 62 characters were considered. These characters have been polarized using the genus Berthella as the outgroup. Eight species of dorids with a radula and the genus Armina have been also included in the analysis for comparative purposes. The phylogeny obtained supports the hypothesis that the radula has been lost once in the Doridina and that the radula-less dorids are a monophyletic group. Cryptobranchia is monophyletic when the radula-less dorids are included. The new genus Mandelia , introduced on the basis of a new species from South Africa, is the sister group of the rest of the radula-less dorids, and is described as a new family, Mandeliidae. The radula-less dorids (currently placed in a separate superfamily) actually constitute an internal branch of other cryptobranch dorids. Phyllidia has no synapomorphies that distinguish if from Fryeria , which has one autoapomorphy, the ventral position of the anus. Therefore, both genera are regarded as synonyms. The evolution of several characters among the radula-less dorids is discussed, and the present phylogeny is compared with prior studies.     

Molecular systematics of the order anaspidea based on mitochondrial DNA sequence (12S, 16S, and COI)

Fragments from three mitochondrial genes (12S, 16S, and COI) were sequenced to reconstruct a molecular phylogeny of the opisthobranch order Anaspidea. The molecular phylogeny supports the placement of the genus Akera, a taxon previously regarded by some authors as a cephalaspidean, within the Anaspidea. Incongruence between the molecular data and the classifications based on morphology suggests that some of the taxonomic characters (i.e., shell, parapodia fusion) traditionally used for the classification of sea hares must be reevaluated, since they may be homoplastic. The ancestral nature of Notarchus based on the molecular evidence suggests that homoplasy may be an explanation for the morphological resemblance of this species to the more derived sea hares with highly fused parapodia and concentrated nerve ganglia. Finally, examples are given of how comparative studies of the evolution of learning mechanisms in the anaspidean clade will benefit from the phylogenetic hypothesis presented in this paper.     

Phylogenetic relationships of antlered flies, Phytalmia Gerstaecker (Diptera: Tephritidae): the evolution of antler shape and mating behaviour

Abstract  The genus Phytalmia (antlered flies, Diptera: Tephritidae) contains remarkable flies with elaborate male head projections known as antlers. The antlers are used in antagonistic intraspecific interactions between males competing to occupy oviposition sites. Phylogenetic relationships between the seven known species of Phytalmia were chosen to be investigated in order to determine the current monophyly of the genus and to assess the evolution of secondary sexual characters and associated behaviours, especially male antlers, fore-femoral, spines and stilting. A phylogenetic analysis of Phytalmia was conducted using two closely related species from the same tribe (Phytalmiini): Sessilina nigrilinea (Walker) and Diplochorda minor Malloch, and one species from a different tribe (Dacini): the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) as outgroups. A total of 1259 base pairs of mitochondrial DNA (COII and 16S) and 35 morphological characters were included in the analysis, using parsimony and maximum likelihood inference methods. A phylogenetic tree generated from combined data was used to infer the evolution of antler shapes and associated behaviours in the genus. The results of this paper support the monophyly of Phytalmia , with P. cervicornis Gerstaecker the sister group of the remaining species. The phylogeny suggests a general decrease in antler complexity over evolutionary time; however, the behavioural sequence of male flies becomes more complex over time, with steps (e.g. stilting) being added to the repertoire during antagonistic encounters. Finally, there are strong correlations between functionally constrained morphological and behavioural characters, therefore allowing the authors to make predications for species whose behaviours are unknown based on morphological attributes and the authors' hypothesised evolution of Phytalmia .     

Phylogeny of the neotropical rove beetle genus Nordus (Coleoptera: Staphylinidae) with a special reference to the evolution of coloration and secondary sexual characters

Abstract. A phylogenetic analysis for Nordus is provided; the monophyly of the genus is established and the phylogenetic relationships of its thirty-eight species are resolved. Analysis of eighty-seven morphological characters, including two coloration characters, produced four equally most-parsimonious trees (tree length = 365, consistency index = 0.38, retention index = 0.66). The coloration of the head and thorax is examined in the context of the reconstructed phylogeny and the evolution of heterochromy is discussed. Golden-orange coloration of the head and thorax evolved in the ancestor of Nordus. Black coloration of the head evolved at least five times, and black coloration of the thorax at least six times within the genus. The evolution of secondary sexual structures in Nordus is also examined in the context of the phylogeny. In males, a medial emarginate abdominal sternum VIII is the ancestral condition. The presence of a single large median lobe on sternum VIII or the presence of two elongate median lobes with a medial emargination on sternum VIII each represent independent evolution of modifications to the male sternum VIII in different lineages. In females, an unmodified abdominal sternum VIII is the ancestral condition. Evolution of an emargination, small lobe or pointed lobe on the margin of sternum VIII in females occurred in different lineages.     

mtDNA ribosomal gene phylogeny of sea hares in the genus Aplysia (Gastropoda,Opisthobranchia, Anaspidea): implications for comparative neurobiology

Sea hares within the genus Aplysia are important neurobiological model organisms; as more studies based on different Aplysia species are appearing in the literature, a phylogenetic framework has become essential. We present a phylogenetic hypothesis for this genus, based on portions of two mitochondrial genes (12S and 16S). In addition, we reconstruct the evolution of several behavioral characters of interest to neurobiologists to illustrate the potential benefits of a phylogeny for the genus Aplysia. These benefits include determination of ancestral traits, direction and timing of evolution of characters, prediction of the distribution of traits, and identification of cases of independent acquisition of traits within lineages. This last benefit may prove especially useful in understanding the linkage between behaviors and their underlying neurological bases.     

Phylogeny and host-plant association in the leaf beetle genus Trirhabda LeConte (Coleoptera: Chrysomelidae)

The leaf beetle genus Trirhabda contains 26 described species from the United States and Canada, feeding on host plants from the families Asteraceae and Hydrophyllaceae. In this study, we present a phylogeny for the genus that was reconstructed from mitochondrial COI and 12S rRNA fragments, nuclear ITS2 rRNA, and morphological characters. Both parsimony and mixed-model Bayesian likelihood analyses were performed. Under both methods, the mitochondrial and nuclear partitions support the same backbone phylogeny, as do the combined data. The utility of the molecular data is contrasted with the low phylogenetic signal among morphological characters. The phylogeny was used to trace the evolution of the host-plant association in Trirhabda. The recovered phylogeny shows that although the host-plant association is phylogenetically conservative, Trirhabda experienced one shift to a distantly related host-plant family, 6 shifts between host-plant tribes, and 6 between genera within tribes. The phylogeny reveals that Trirhabda were plesiomorphically adapted to tolerate complex secondary compounds of its host plants and this adaptation is retained in Trirhabda species, as evidenced by multiple shifts from chemically simpler host plants back to the more complex host plants.     

The ecology and behaviour of a marine insect, Halobates fijiensis (Hemiptera: Gerridae)

Observations were made in Fiji on the adaptive strategies of a marine gerrid, Halobates fijiensis , a species of the only genus of insects to have successfully colonized the open sea. The immature stages spend most of their time in flotillas on sheltered water close to mangroves, whereas adults usually occur singly and on both sheltered and open water behind the protecting reef systems. Wind has a decisive influence on the distribution of H. fijiensis: in strong onshore winds, all stages, including adults, remain close to the shelter of mangroves, but in calm conditions, older immatures venture considerable distances from the mangroves. Halobates fijiensis feed on floating, dead insects. Adults of the chironomid fly Tanytarsus halophilae , whose larvae live on intertidal sea-grasses, accounted for over 60% of the prey items recorded. Halobates fijiensis feeds at around the time of high water, either as individuals or in small, well-dispersed groups. Eggs are laid on intertidal turtle grass (Syringodium) , green coralline algae (Halimeda) or occasionally coral rubble, at or shortly after the point of low water on days of extreme low spring tides. Halobates fijiensis is preyed upon by the robber-fly Clinopogon scalaris (Diptera: Asilidae). Field observations showed that there is a clear effect of group size on the distance at which an approaching predator model is detected.     

Evolutionary aspects of cephalic sensory papillae of the Indo‐Pacific species of Eleotris (Teleostei: Eleotridae)

Eleotris species (Teleostei: Eleotridae) are one of the most common fish in Indo‐Pacific estuaries and insular freshwater streams. In these rivers, they are a sit‐and‐wait predator. They have an amphidromous life cycle, that is adults grow, feed and reproduce in rivers, while larvae have a marine dispersal phase. Larvae recruit back to rivers and settle in stream habitats. Primary characters used to determine Eleotris species are the presence and the disposition of cephalic sensory papillae rows on the operculum and under the eyes as well as scale row numbers. The morphology of these cephalic sensory papillae is of particular importance in this predatory genus as it is generally correlated in fish to predation and feeding. In this paper, we have established a molecular phylogeny of the genus based on the 12 mitochondrial protein‐coding genes to discuss the relationship between Indo‐Pacific Eleotris species. There is a well‐supported dichotomy in the molecular phylogeny, and this separation into two main clades is also morphologically visible, as it reveals a difference in the arrangement of cephalic sensory papillae. Indeed, the phylogeny distinguishes the species with the “open” pattern of the operculum sensory papillae and the species with the “closed” one. This phylogeny thus reflects the morphology of the opercular papillae. The evolution of this character is discussed in terms of the adaptation of the Eleotris genus to life in tropical insular river systems.     

A phylogeny of the ITS and ETS for Montanoa (Asteraceae: Heliantheae)

A phylogeny of the genus Montanoa based on the internal transcribed spacer (ITS) and the external transcribed spacer (ETS) is presented. Each of the two clades revealed by the Bayesian and parsimony analyses has approximately half of the number of species in the genus. One lineage is composed mostly of central and southern Mexican species whereas the other lineage contains those species endemic to Mesoamerica and South America. The molecular phylogeny is compared to previous phylogenetic hypotheses based on morphological characters. Key features in the structure of the capitulum such as pale morphology, heavily used in the past to construct hypotheses of relationship within the genus, are viewed as of minimal value to circumscribe natural groups. The relationships of Montanoa to other genera in the Heliantheae are briefly discussed.     

Phylogeny of the Neotropical moth tribe Josiini (Notodontidae: Dioptinae): a hidden case of Miillerian mimicry

The Neotropical moth tribe Josiini (Notodontidae: Dioptinae) contains over 100 described species in 11 genera. All are diurnal, with brightly-coloured, presumably aposematic wing patterns. Larval hostplants are exclusively in the genus Passiflora (Passifloraceae) except for two new records, reported here, from Tumera (Turneraceae). A comparative morphological study of 26 representative josiine species yielded 86 characters from adults, larvae and pupae, all of which are figured and discussed. Phylogenetic analysis of these data produced a single most-parsimonious cladogram. According to the phylogenetic results: (1) monophyly of the Josiini is strongly supported; (2) the currently accepted generic classification is in disarray; (3) morphological character variation is extensive, and adult traits reflect phylogeny more effectively than do those of immature stages; (4) wing pattern types have undergone convergent evolution. A rare phenotype, longitudinal wing stripes, appears in two widely divergent clades, suggesting the evolution of Miillerian mimicry within the Josiini.     

Molecular phylogenetic approach for studying life-history evolution: the ambiguous example of the genus Medicago L.

We present a molecular phylogeny including most species of the genus Medicago L. (Fabaceae). Based on the consensus of the 48 most parsimonious trees, life-history and mating-system characters are mapped, and a putative history of the genus is suggested. The most parsimonious reconstruction suggests an ancestral annual and selfing state, and recurrent evolution towards perenniality and outcrossing. Based on theoretical predictions and classical hypotheses of the history of the genus, different assumptions about the ancestral state and different weighting schemes of evolution between the character states are made. Assuming an outcrossing, perennial ancestral state (partly supported by morphological features) does not fundamentally change the reconstruction. To meet theoretical expectations, various weighting schemes favouring evolution towards annuality and selfing are applied. Influence and validity of such weighting schemes are discussed with regard to other studies.