Redescription of Eatonisca tertiaria Meunier 1905 from Baltic amber (Diptera: Psychodidae: Trichomyiinae)

Eatonisca tertiaria Meunier 1905, is redescribed from the Eocene Baltic amber, with details of the eyes, antennae and male genitalia structure provided. This fossil is placed within Trichomyiinae, and shares several plesiomorphies with Psychodinae, Phlebotominae, and Sycoracinae.     

Phylogeny of psychodid subfamilies (Diptera: Psychodidae) inferred from nuclear DNA sequences with a review of morphological evidence for relationships

Psychodidae is a diverse family of flies with approximately 3000 described species in six subfamilies, including Phlebotominae vectors of human disease. Psychodidae has been the subject of few phylogenetic investigations and development of a stable classification has been hampered by poor understanding of the morphology of larvae, pupae and adults. Specimens were collected, and we analysed DNA sequence data from two nuclear genes for one or more representatives of all subfamilies. The subfamilies with multiple representatives included were resolved as monophyletic with good support. Placement of Horaiellinae, Sycoracinae and Trichomyiinae remains unclear, whereas Bruchomyiinae is hypothesized as the sister group to (Phlebotominae + Psychodinae). Representatives of some psychodine tribes were resolved in agreement with previous hypotheses. Relationships among and within subfamilies are discussed, and morphological characters supporting these relationships are reviewed. One compelling synapomorphy of the male genitalia supporting a relationship between Phlebotominae and Psychodinae is the presence of articulated surstyli with apical retinacula. Only cerci are present and sometimes developed into clasping structures in males of other subfamilies.     

Investigating cortical features of Sotos syndrome using mice heterozygous for Nsd1

Sotos syndrome is a developmental disorder characterized by a suite of clinical features. In children, the three cardinal features of Sotos syndrome are a characteristic facial appearance, learning disability and overgrowth (height and/or head circumference > 2 SDs above average). These features are also evident in adults with this syndrome. Over 90% of Sotos syndrome patients are haploinsufficient for the gene encoding nuclear receptor‐binding Su(var)3‐9, Enhancer‐of‐zesteand Trithorax domain‐containing protein 1 (NSD1). NSD1 is a histone methyltransferase that catalyzes the methylation of lysine residue 36 on histone H3. However, although the symptomology of Sotos syndrome is well established, many aspects of NSD1 biology remain unknown. Here, we assessed the expression of Nsd1 within the mouse brain, and showed a predominantly neuronal pattern of expression for this histone‐modifying factor. We also generated a mouse strain lacking one allele of Nsd1 and analyzed morphological and behavioral characteristics in these mice, showing behavioral characteristics reminiscent of some of the deficits seen in Sotos syndrome patients.     

Evolution and diversification of a sexually dimorphic luminescent system in ponyfishes (Teleostei: Leiognathidae), including diagnoses for two new genera

A phylogeny was generated for Leiognathidae, an assemblage of bioluminescent, Indo‐Pacific schooling fishes, using 6175 characters derived from seven mitochondrial genes (16S, COI, ND4, ND5, tRNA‐His, tRNA‐Ser, tRNA‐Leu), two nuclear genes (28S, histone H3), and 15 morphological transformations corresponding to features of the fishes' sexually dimorphic light‐organ system (LOS; e.g., circumesophageal light organ, lateral lining of the gas bladder, transparent flank and opercular patches). Leiognathidae comprises three genera, Gazza, Leiognathus, and Secutor. Our results demonstrate that Leiognathidae, Gazza, and Secutor are monophyletic, whereas Leiognathus is not. The recovered pattern of relationships reveals that a structurally complex, strongly sexually dimorphic and highly variable species‐specific light organ is derived from a comparatively simple non‐dimorphic structure, and that evolution of other sexually dimorphic internal and external features of the male LOS are closely linked with these light‐organ modifications. Our results demonstrate the utility of LOS features, both for recovering phylogeny and resolving taxonomic issues in a clade whose members otherwise exhibit little morphological variation. We diagnose two new leiognathid genera, Photopectoralis and Photoplagios, on the basis of these apomorphic LOS features and also present derived features of the LOS to diagnose several additional leiognathid clades, including Gazza and Secutor. Furthermore, we show that five distinct and highly specialized morphologies for male‐specific lateral luminescence signaling, which exhibit species‐specific variation in structure, have evolved in these otherwise outwardly conservative fishes. Leiognathids inhabit turbid coastal waters with poor visibility and are often captured in mixed assemblages of several species. We hypothesize that the species‐specific, sexually dimorphic internal and external modifications of the leiognathid LOS provide compelling evidence for an assortative mating scheme in which males use species‐specific patterns of lateral luminescence signaling to attract mates, and that this system functions to maintain reproductive isolation in these turbid coastal environments. © The Willi Hennig Society 2005.     

Non‐genetic polymorphisms in rotifers: environmental and endogenous controls,development, and features for predictable or unpredictable environments

Pronounced non‐genetic polymorphisms, or polyphenisms, occur in some monogonont rotifers reproducing by diploid, female parthenogenesis. In many brachionids, there is great variation in spine length. In trimorphic species of Asplanchna, females can vary in size and shape, from a small saccate morph to giant cruciform and campanulate morphs. In species that also reproduce sexually, diploid eggs can develop into two types of females. Amictic females produce diploid eggs that develop parthenogenetically into females; mictic females produce haploid eggs that develop parthenogenetically into males or, if fertilized, into resting eggs. In a species of Synchaeta, amictic females produce diploid eggs that can be either thin‐shelled and subitaneous or thicker‐shelled and diapausing. In all cases, morph determination occurs during the oogenesis or embryological development of diploid eggs in the maternal body cavity. For the first time, these polymorphisms are reviewed together and compared regarding a number of features associated with transitions from default to induced morphs: (i) type of variation (morphological, physiological, or both; continuous or discrete); (ii) inducing signal (environmental, endogenous, or both); (iii) universality of response to that signal (all or only some individuals); (iv) fitness cost; (v) reversibility; and (vi) ecological significance. Most of the polymorphisms fall into two major categories regarding these features. Transitions suitable for predictable environments involve: universal responses to environmental signals; continuous morphological variation; low reproductive cost; rapid reversibility; and adaptations for defence, hydrodynamics or prey ingestion. Transitions suitable for unpredictable environments are bet‐hedging strategies and usually involve: partial (stochastic) responses to environmental or endogenous signals; discontinuous physiological variation; initiation of diapause, and thus high reproductive cost and slow reversibility. Two cases of morphological variation also involve the simultaneous production of different morphs and likely are adaptations for an uncertain future: continuous spine‐length variation due to maternal age in Brachionus calyciflorus, and production of discrete cruciform and campanulate females in Asplanchna spp.     

A first view on the unsuspected intragenus diversity of N‐glycans in Chlorella microalgae

Chlorella microalgae are increasingly used for various purposes such as fatty acid production, wastewater processing, or as health‐promoting food supplements. A mass spectrometry‐based survey of N‐glycan structures of strain collection specimens and 80 commercial Chlorella products revealed a hitherto unseen intragenus diversity of N‐glycan structures. Differing numbers of methyl groups, pentoses, deoxyhexoses, and N‐acetylglucosamine culminated in c. 100 different glycan masses. Thirteen clearly discernible glycan‐type groups were identified. Unexpected features included the occurrence of arabinose, of different and rare types of monosaccharide methylation (e.g. 4‐O‐methyl‐N‐acetylglucosamine), and substitution of the second N‐acetylglucosamine. Analysis of barcode ITS1–5.8S–ITS2 rDNA sequences established a phylogenetic tree that essentially went hand in hand with the grouping obtained by glycan patterns. This brief prelude to microalgal N‐glycans revealed a fabulous wealth of undescribed structural features that finely differentiated Chlorella‐like microalgae, which are notoriously poor in morphological attributes. In light of the almost identical N‐glycan structural features that exist within vertebrates or land plants, the herein discovered diversity is astonishing and argues for a selection pressure only explicable by a fundamental functional role of these glycans.     

Ecology and phylogenetic affinity of the early Cambrian tubular microfossil Megathrix longus

Abundant, exquisitely preserved specimens of the enigmatic tubular microfossil Megathrix longus are reported from the early Cambrian Yanjiahe Formation in the Yangtze Gorges area. Studies of their morphology and taphonomy reveal that the inner cross‐wall of Megathrix longus is topographically flat, the trichome terminus is blunt and closed, and incomplete cross‐walls are regularly intercalated between complete ones. The deformation of trichomes, as well as the corrugation of their cross‐walls, are postmortem features caused by compaction, rather than biological features as previously interpreted. Statistical analysis indicates that chamber division is accomplished by the closure of incomplete cross‐walls. This process, which contributed to trichome growth, is extremely similar to that of modern Oscillatoriaceae. Trichome fragmentation was also observed in a series of specimens, which closely resembles that of cyanobacteria, particularly the Oscillatoriaceae. The termini of Megathrix longus suggest that it was planktonic. In general, Megathrix longus bears a close affinity to the extant Oscillatoriaceae (Cyanophyta).     

First partial face and upper dentition of the Middle Miocene hominoid Dryopithecus fontani from Abocador de Can Mata (Vallès‐Penedès Basin,Catalonia, NE Spain): Taxonomic and phylogenetic implications

A well‐preserved 11.8‐million‐years‐old lower face attributed to the seminal taxon Dryopithecus fontani (Primates, Hominidae) from the Catalan site ACM/C3‐Ae of the Hostalets de Pierola area (Vallès‐Penedès Basin, Catalonia, NE Spain) is described. The new data indicate that D. fontani is distinct at the genus level from Late Miocene European taxa previously attributed to Dryopithecus, which are here reassigned to Hispanopithecus. The new facial specimen also suggests that D. fontani and the Middle Miocene Pierolapithecus catalaunicus are not synonymous. Anatomical and morphometric analyses further indicate that the new specimen shows a combination of lower facial features—hitherto unknown in Miocene hominoids—that resembles the facial pattern of Gorilla, thus providing the first nondental evidence of gorilla‐like lower facial morphology in the fossil record. Considering the current evidence, the gorilla‐like facial pattern of D. fontani is inferred to be derived relative to previously known stem hominids, and might indicate that this taxon is either an early member of the Homininae or, alternatively, a stem hominid convergent with the lower facial pattern of Gorilla. The biogeographic implications of both alternatives are discussed. This new finding in the Hostalets de Pierola section reinforces the importance of this area for understanding the elusive question of the Middle Miocene origin and early radiation of great apes. Am J Phys Anthropol, 2009. © 2009 Wiley‐Liss, Inc.     

Small Organic Solutes in Sticky Droplets from Orb Webs of the Spider Zygiella atrica (Araneae; Araneidae): β‐Alaninamide Is a Novel and Abundant Component

In northeastern North America, Zygiella atrica often build their orb webs near the ocean. We analyzed individual field‐built Z. atrica webs to determine if organic low‐molecular‐mass solutes (LMM) in their sticky droplets showed any unusual features not previously seen in orb webs of other species living in less salty environments. While two of the three most abundant organic LMM (putrescine (butane‐1,4‐diamine) and GABamide (4‐aminobutanamide)) are already well‐known from webs of inland spiders, the third major LMM, β‐alaninamide (3‐aminopropanamide), a homolog of GABamide, has not been detected in sticky droplets from any other araneoid spiders (27 species). It remains to be established, however, whether or not use of β‐alaninamide is related to proximity to saltwater. We observed variability in organic LMM composition in Z. atrica webs that appeared to be influenced more by an undetermined factor associated with different collecting locations and/or collection dates than by different genders or instars. Shifts in composition when adult females were transferred from the field to the laboratory were also observed. Structural similarities and inverse correlations among β‐alaninamide, GABamide, and N‐acetylputrescine suggest that they may form a series of LMM fulfilling essentially the same, as yet unknown, role in the webs of those species in which they occur.     

A mineralogical characterization of biogenic calcium carbonates precipitated by heterotrophic bacteria isolated from cryophilic polar regions

Precipitation of calcium carbonate (CaCO_3(s)) can be driven by microbial activity. Here, a systematic approach is used to identify the morphological and mineralogical characteristics of CaCO_3(s) precipitated during the heterotrophic growth of micro‐organisms isolated from polar environments. Focus was placed on establishing mineralogical features that are common in bioliths formed during heterotrophic activity, while in parallel identifying features that are specific to bioliths precipitated by certain microbial phylotypes. Twenty microbial isolates that precipitated macroscopic CaCO_3(s) when grown on B4 media supplemented with calcium acetate or calcium citrate were identified. A multimethod approach, including scanning electron microscopy, high‐resolution transmission electron microscopy, and micro‐X‐ray diffraction (μ‐XRD), was used to characterize CaCO_3(s) precipitates. Scanning and transmission electron microscopy showed that complete CaCO_3(s) crystal encrustation of Arthrobacter sp. cells was common, while encrustation of Rhodococcus sp. cells did not occur. Several euhedral and anhedral mineral formations including disphenoid‐like epitaxial plates, rhomboid‐like aggregates with epitaxial rhombs, and spherulite aggregates were observed. While phylotype could not be linked to specific mineral formations, isolates tended to precipitate either euhedral or anhedral minerals, but not both. Three anhydrous CaCO_3(s) polymorphs (calcite, aragonite, and vaterite) were identified by μ‐XRD, and calcite and aragonite were also identified based on TEM lattice‐fringe d value measurements. The presence of certain polymorphs was not indicative of biogenic origin, although several mineralogical features such as crystal‐encrusted bacterial cells, or casts of bacterial cells embedded in mesocrystals are an indication of biogenic origin. In addition, some features such as the formation of vaterite and bacterial entombment appear to be linked to certain phylotypes. Identifying phylotypes consistent with certain mineralogical features is the first step toward discovering a link between these crystal features and the precise underlying molecular biology of the organism precipitating them.     

Craniodental mechanics and diet in Asian colobines: Morphological evidence of mature seed predation and sclerocarpy

Folivory has been accepted as the general dietary pattern for colobines. However, recent ecological studies have revealed that extensive seed eating is found in some colobine species. The ripeness of foraged seeds is also reported to differ between seed eaters. As seeds are generally stress‐limited and may pose greater mechanical demands, seed‐eating species are predicted to exhibit morphological features adaptive for seed predation. In addition, species that feeds on seeds from unripe fruits with hard pericarp is predicted to exhibit increased leverage for anterior dentition. To test these hypotheses, we compared the craniodental morphology of seed‐eating Asian colobines (Presbytis rubicunda and Trachypithecus phayrei) with those of species that rarely exploit seeds (Presbytis comata, Trachypithecus obscurus, and Semnopithecus vetulus). The results show that the seed‐eating colobines possess a masticatory system with enhanced leverage at postcanine bite points. The sclerocarpic forager P. rubicunda also exhibits markedly greater masticatory leverage at anterior dental bite points, while the mature‐seed‐eating T. phayrei shows no such advantage for canine and incisor use. These observations suggest that P. rubicunda is well adapted to husking the resistant pericarps of unripe fruits, using the anterior dentition and to gain access to the immature seeds, whereas such sclerocarpic feeding behavior may be less important for T. phayrei. Our findings indicate that the distinctive craniodental variations of colobines may be linked to mature and/or immature seed eating and suggest the significance of seed predation for the evolution of colobine monkeys. Am J Phys Anthropol, 2010. © 2010 Wiley‐Liss, Inc.     

Accuracy of Self‐reported Weight and Height in Binge Eating Disorder: Misreport Is Not Related to Psychological Factors

This study examined the degree of misreport in weight, height, and BMI among overweight adults (n = 392) with binge eating disorder (BED) and tested whether the degree of misreport was associated with eating disorder psychopathology and psychological variables. Male (n = 97) and female (n = 295) participants self‐reported height and weight, and were subsequently measured by clinic staff. Participants also completed a series of diagnostic interviews and self‐report assessments. Discrepancies between self‐reported and measured values were modest. The degree of misreport for weight, height, and BMI was not related to eating disorder features, depression, and self‐esteem. Overall, the errors in self‐reported weight and height by overweight patients with BED were very slight. The degree of discrepancy between self‐reported and measured values was not related to eating disorder or psychological features, suggesting that such data are not biased or systematically related to individual differences in overweight patients with BED.     

Improving 2‐DE gel image denoising using contourlets

One of the most commonly used methods for protein separation is 2‐DE. After 2‐DE gel scanning, images with a plethora of spot features emerge that are usually contaminated by inherent noise. The objective of the denoising process is to remove noise to the extent that the true spots are recovered correctly and accurately i.e. without introducing distortions leading to the detection of false‐spot features. In this paper we propose and justify the use of the contourlet transform as a tool for 2‐DE gel images denoising. We compare its effectiveness with state‐of‐the‐art methods such as wavelets‐based multiresolution image analysis and spatial filtering. We show that contourlets not only achieve better average S/N performance than wavelets and spatial filters, but also preserve better spot boundaries and faint spots and alter less the intensities of informative spot features, leading to more accurate spot volume estimation and more reliable spot detection, operations that are essential to differential expression proteomics for biomarkers discovery.     

Comparative anatomy of leaves and stems in some species of the South American genus Chrysolaena (Vernonieae,Asteraceae) and taxonomic implications

Vegetative anatomical features are poorly known in the South American genus Chrysolaena. In this study, leaves and stems of six Chrysolaena species were described and compared morphologically and anatomically using diaphanization, microtome serial sectioning and scanning electron microscopy. The species differed in leaf epidermis, type of stomata, shape of anticlinal walls of epidermal cells, trichome density, and presence or absence in stems of small air spaces in the cortical parenchyma and of druse‐shaped oxalate crystals. Furthermore, glandular trichomes and three types of non‐glandular trichomes with different number of basal cells were identified on leaves and stems. Collectively, these features proved instrumental to discriminate among the six studied species, suggesting that leaves and stems of Chrysolaena can represent a source for taxonomically useful characters. We also discuss anatomical features in relation to the environmental conditions in the species’ habitats.     

Stem cells in asexual reproduction of Enchytraeus japonensis (Oligochaeta, Annelid): proliferation and migration of neoblasts

Enchytraeus japonensis is a small oligochaete that reproduces mainly asexually by fragmentation (autotomy) and regeneration. As sexual reproduction can also be induced, it is a good animal model for the study of both somatic and germline stem cells. To clarify the features of stem cells in regeneration, we investigated the proliferation and lineage of stem cells in E. japonensis. Neoblasts, which have the morphological characteristics of undifferentiated cells, were found to firmly adhere to the posterior surface of septa in each trunk segment. Also, smaller neoblast‐like cells, which are designated as N‐cells in this study, were located dorsal to the neoblasts on the septa. By conducting 5‐bromo‐2′‐deoxyuridine (BrdU)‐labeling‐experiments, we have shown that neoblasts are slow‐cycling (or quiescent) in intact growing worms, but proliferate rapidly in response to fragmentation. N‐cells proliferate more actively than do neoblasts in intact worms. The results of pulse‐chase experiments indicated that neoblast and N‐cell lineage mesodermal cells that incorporated BrdU early in regeneration migrated toward the autotomized site to form the mesodermal region of the blastema, while the epidermal and intestinal cells also contributed to the blastema locally near the autotomized site. We have also shown that neoblasts have stem cell characteristics by expressing Ej‐vlg2 and by the activity of telomerase during regeneration. Telomerase activity was high in the early stage of regeneration and correlated with the proliferation activity in the neoblast lineage of mesodermal stem cells. Taken together, our results indicate that neoblasts are mesodermal stem cells involved in the regeneration of E. japonensis.     

The reality and evolutionary significance of human psychological sex differences

The aims of this article are: (i) to provide a quantitative overview of sex differences in human psychological attributes; and (ii) to consider evidence for their possible evolutionary origins. Sex differences were identified from a systematic literature search of meta‐analyses and large‐sample studies. These were organized in terms of evolutionary significance as follows: (i) characteristics arising from inter‐male competition (within‐sex aggression; impulsiveness and sensation‐seeking; fearfulness; visuospatial and object‐location memory; object‐centred orientations); (ii) those concerning social relations that are likely to have arisen from women's adaptations for small‐group interactions and men's for larger co‐operative groups (person‐centred orientation and social skills; language; depression and anxiety); (iii) those arising from female choice (sexuality; mate choice; sexual conflict). There were sex differences in all categories, whose magnitudes ranged from (i) small (object location memory; negative emotions), to (ii) medium (mental rotation; anxiety disorders; impulsivity; sex drive; interest in casual sex), to (iii) large (social interests and abilities; sociosexuality); and (iv) very large (escalated aggression; systemizing; sexual violence). Evolutionary explanations were evaluated according to whether: (i) similar differences occur in other mammals; (ii) there is cross‐cultural consistency; (iii) the origin was early in life or at puberty; (iv) there was evidence for hormonal influences; and (v), where possible, whether there was evidence for evolutionarily derived design features. The evidence was positive for most features in most categories, suggesting evolutionary origins for a broad range of sex differences. Attributes for which there was no sex difference are also noted. Within‐sex variations are discussed as limitations to the emphasis on sex differences.     

Haemorrhagic toxin and lethal toxin from Clostridium sordellii strain vpi9048: molecular characterization and comparative analysis of substrate specificity of the large clostridial glucosylating toxins

Large clostridial glucosylating toxins (LCGTs) are produced by toxigenic strains of Clostridium difficile, Clostridium perfringens, Clostridium novyi and Clostridium sordellii. While most C. sordellii strains solely produce lethal toxin (TcsL), C. sordellii strain VPI9048 co‐produces both hemorrhagic toxin (TcsH) and TcsL. Here, the sequences of TcsH‐9048 and TcsL‐9048 are provided, showing that both toxins retain conserved LCGT features and that TcsL and TcsH are highly related to Toxin A (TcdA) and Toxin B (TcdB) from C. difficile strain VPI10463. The substrate profile of the toxins was investigated with recombinant LCGT transferase domains (rN) and a wide panel of small GTPases. rN‐TcsH‐9048 and rN‐TcdA‐10463 glucosylated preferably Rho‐GTPases but also Ras‐GTPases to some extent. In this respect, rN‐TcsH‐9048 and rN‐TcdA‐10463 differ from the respective full‐length TcsH‐9048 and TcdA‐10463, which exclusively glucosylate Rho‐GTPases. rN‐TcsL‐9048 and full length TcsL‐9048 glucosylate both Rho‐ and Ras‐GTPases, whereas rN‐TcdB‐10463 and full length TcdB‐10463 exclusively glucosylate Rho‐GTPases. Vero cells treated with full length TcsH‐9048 or TcdA‐10463 also showed glucosylation of Ras, albeit to a lower extent than of Rho‐GTPases. Thus, in vitro analysis of substrate spectra using recombinant transferase domains corresponding to the auto‐proteolytically cleaved domains, predicts more precisely the in vivo substrates than the full length toxins. Except for TcdB‐1470, all LCGTs evoked increased expression of the small GTPase RhoB, which exhibited cytoprotective activity in cells treated with TcsL isoforms, but pro‐apoptotic activity in cells treated with TcdA, TcdB, and TcsH. All LCGTs induced a rapid dephosphorylation of pY118‐paxillin and of pS144/141‐PAK1/2 prior to actin filament depolymerization indicating that disassembly of focal adhesions is an early event leading to the disorganization of the actin cytoskeleton.     

SYSTEMATICS OF THE GENUS ZYGNEMA (ZYGNEMATOPHYCEAE,CHAROPHYTA) FROM CALIFORNIAN WATERSHEDS1

Natural populations of Zygnema were collected from 80 stream sites across California, and eight species were identified and characterized morphologically. Generic and infrageneric concepts of Zygnema and Zygogonium were tested with cox3 and rbcL gene sequence analysis. Strains of Zygnema were positioned in a single monophyletic clade sister to Zygogonium tunetanum Gauth.‐Lièvre. In both the rbcL and cox3 phylogenies, strains of Zygnema formed two major clades. The first clade contained species that have zygospores with a blue‐colored mesospore or akinetes with a colorless mesospore. The second clade contained species that have a yellow or brown mesospore. The existing taxonomic concepts for Zygnema classification are not consistent with our molecular phylogeny and do not correspond to natural groups. We propose that mesospore color may be useful in the infrageneric classification of Zygnema. Newly described Zygnema aplanosporum sp. nov. and Zygnema californicum sp. nov. have zygospores with a blue mesospore formed in the conjugation tube and separated by a cellulosic sporangial wall. Z. aplanosporum also possessed a combination of vegetative and reproductive features characteristic of Zygogonium, such as presence of short branches, rhizoidal outgrowths, thickened vegetative cell walls, purple‐colored cell content, small compressed‐globular chloroplasts as well as predominant asexual reproduction. Z. aplanosporum and Z. californicum were deeply embedded in a larger clade of Zygnema both in rbcL and cox3 analyses. Based on our observations, there are no features or combination of features that separate Zygnema and Zygogonium. Therefore, we conclude that Zygogonium is probably a synonym of Zygnema.     

Phylogenetic analysis of the pearlfish tribe Carapini (Pisces: Carapidae)

Fishes of the tribe Carapini (Encheliophis and Carapus) share a noteworthy peculiarity: they shelter in holothurian echinoderms or bivalve hosts. Some species are considered parasitic, others commensal. This study focuses on the phylogeny of the tribe, using two other Carapidae species as an outgroup (Snyderidia canina and Onuxodon fowleri). Insofar as possible, the selected anatomical and behavioural characters where chosen in an ecomorphological perspective, as features that could be responses to various lifestyle‐related constraints. Our character selection also took into account the fact that some features are (presumably) linked. Such features were grouped together as a single trait to avoid their overvaluation. This methodology enabled commensals to be separated from parasites, the former belonging to Carapus and the latter to Encheliophis. Carapus species reflect in their morphology the constraints imposed by a diet of hard, mobile, elusive prey, showing predator‐type features: a strong dentition, a wide mouth opening, a robust food intake apparatus. On the other hand, the endoparasitic Encheliophis species show a generally weaker buccal apparatus and narrow mouth opening, in relation to the different constraints of their lifestyle where the diet constraints are less pronounced: they eat body parts of their host. Changes in both generic diagnoses are proposed and three species are transferred from Encheliophis to Carapus.