Larval Morphotypes Research Articles

New records of immature aquatic Diptera from the Foulden Maar Fossil-Lagerstätte, New Zealand, and their biogeographic implications.

The biogeographical and ecological history of true flies (Diptera) in New Zealand is little known due to a scarcity of fossil specimens. Here, we report a fauna of immature aquatic dipterans from freshwater diatomites of the early Miocene Foulden Maar Fossil-Lagerstätte in southern New Zealand. We document 30 specimens of immature dipterans, mostly pupae, and compare their external morphology to extant aquatic Diptera. Based on the reconstructed paleoenvironment of Foulden Maar, we discuss taxonomic, ecological and taphonomic implications of this early Miocene fauna. Among Chironomidae, one pupal morphotype is attributed to Tanypodinae, one pupal morphotype and one larval morphotype are placed into Chironomus (Chironominae) and a further morphotype into Chironominae incertae sedis. Chaoboridae are represented by a pupal morphotype congeneric or very close to the extant Chaoborus, today globally distributed except for New Zealand. Additional immature specimens are likely larvae and puparia of brachyceran flies but cannot be identified to a narrower range. These finds document an aquatic dipteran fauna in New Zealand in the earliest Miocene and highlight Neogene extinction as a factor in shaping the extant Diptera fauna in New Zealand. Immature aquatic dipterans were a common and likely ecologically important component of the early Miocene Foulden Maar lake. Preservation of larvae and pupae may have been promoted by diatomaceous microbial mats and the light colour of the diatomite likely facilitated spotting of these minute fossils in the field.

Larval morphology and natural history in two Minervarya species from Andaman Islands, with comments on a new phytotelmonous larval morphotype for the genus.

We studied the larval morphology and natural history of two species of Minervarya from the Andaman Islands of India. A recent assignment of Charles Darwins frog to the genus Minervarya opened up new questions on the systematic affinities and natural history of its enigmatic tadpoles. Originally described as Rana charlesdarwini Das, 1998, and long considered as Ingerana charlesdarwini, the tadpoles of this species were poorly understood and incomparable to those of other presumed close relatives based on an original brief description of its phytotelmonous tadpoles. Here we present a detailed redescription of the larval morphology of M. charlesdarwini based on genetically confirmed tadpoles. At the same time, we compared the external morphology of M. charlesdarwini tadpoles to that of its closest phylogenetic and sympatric congener, M. andamanensis, consequently reporting the first-ever larval description for M. andamanensis. For the first time also for minervaryan frogs, we record that M. charlesdarwini lays eggs on the inner walls of tree holes, and the tadpoles possess morphological adaptations for a phytotelmonous life. Their unique features, such as tail-to-body ratio >2.2, reduced labial tooth rows (LTRF 1/1), acutely pointed serrations in the jaw sheath, and the medial portion of the upper sheath broadly arched and that of the lower sheath U-shaped, justify adding a new larval morphotype to the genus Minervarya. In contrast, M. andamanensis breeds and undergoes development in ground water puddles and ponds, a common trait for other known minervaryan species. Furthermore, our study generates new knowledge on the amplexus, oviposition site, and early embryonic development in these species. The deeper understanding of the biology and habitat requirements contributes additional traits for future systematic and evolutionary studies, and helps guide conservation assessments for these two species endemic to a handful of islands in the Andaman Archipelago.

A revision of the Chilean water penny genus Tychepsephus Waterhouse, 1876 (Coleoptera, Psephenidae, Eubriinae), with description of a second species and two larval morphotypes, and notes on other Chilean Psephenidae.

The Chilean water penny genus Tychepsephus Waterhouse, 1876 is revised, with descriptions and photographic illustrations of life stages including two larval morphotypes, the pupa of one morphotype, and adults of two species. The pupa of Tychepsephus has not been reported previously. Tychepsephuscekalovicisp. nov. is described, and Ectopria (Chilectopria) grandis Pic, 1947, syn. nov. is proposed as a new synonym of Tychepsephusfelix Waterhouse, 1876, which is redescribed. Taxonomic treatment of the adults of both species includes images of the habitus of males and females, morphological variation, and male and female genitalia. Males and females are sexually dimorphic. Information on the habitat of Tychepsephus is provided and illustrated with photographs, and the known geographic distribution of the two species is mapped. The occurrence of Tychepsephus in Argentina is reported; therefore, the genus no longer can be considered endemic to Chile. The taxonomic status and geographic distribution in South America of other species of Psephenidae, particularly members of the subfamily Eubriinae, is reviewed.

Morphological and molecular characterization of Hysterothylacium larval morphotypes (Nematoda: Raphidascarididae) infecting edible marine fish in the Black Sea.

The morphological and molecular identification of Hysterothylacium larval morphotypes in the Black Sea remains unresolved and incomplete. The aim of current study was to provide a detailed morphological identification with rDNA whole ITS (ITS‒1, 5.8S subunit, ITS‒2) and mtDNA cox2 sequences data of Hysterothylacium larval morphotypes infecting four commonly edible marine fish species, including European anchovy, Engraulis encrasicolus (L.), horse mackerel, Trachurus trachurus (L.), whiting, Merlangius merlangus (L.), and red mullet, Mullus barbatus ponticus (E.) in the Black Sea (FAO fishing area 37.4.2). Hysterothylacium larval morphotypes were morphologically classified, followed by whole ITS and cox2 sequencing. Four Hysterothylacium larval morphotypes, III, IV, VIII, and IX, are described based on morphological and molecular data. The present study provides the first study reporting whole ITS and cox2 sequences for Hysterothylacium larval morphotypes III, IV, VIII and III, IV, VIII, IX, respectively, in the Black Sea. Here, we offer a foundation for future research on the distribution, morphologic and molecular identification of Hysterothylacium larval morphotypes infecting edible some marine fish in the Black Sea.

Hawaiian larval stomatopods: molecular and morphological diversity

Estimating stomatopod species diversity using morphology alone has long been difficult; though over 450 species have been described, new species are still being discovered regularly despite the cryptic behaviors of adults. However, the larvae of stomatopods are more easily obtained due to their pelagic habitat, and have been the focus of recent studies of diversity. Studies of morphological diversity describe both conserved and divergent traits in larval stomatopods, but generally cannot be linked to a particular species. Conversely, genetic studies of stomatopod larvae using DNA barcoding can be used to estimate species diversity, but are generally not linked to known species by analyses of morphological characters. Here we combine these two approaches, larval morphology and genetics, to estimate stomatopod species diversity in the Hawaiian Islands. Over 22 operational taxonomic units (OTUs) were identified genetically, corresponding to 20 characterized morphological types. Species from three major superfamilies of stomatopod were identified: Squilloidea (4 OTUs, 3 morphotypes), Gonodactyloidea (9, 8), and Lysiosquilloidea (6, 7). Among these, lysiosquilloids were more diverse based on larval morphotypes and OTUs as compared to previously documented Hawaiian species (3), while squilloids had a lower diversity of species represented by collected larvae as compared to the seven species previously documented. Two OTUs / morphotypes could not be identified to superfamily as their molecular and morphological features did not closely match any available information, suggesting they belong to poorly sampled superfamilies. The pseudosquillid, Pseudosquillana richeri, was discovered for the first time from Hawai'i. This study contributes an updated estimate for Hawaiian stomatopod diversity for a total of 24 documented species, provides references for identification of larval stomatopods across the three major superfamilies, and emphasizes the lack of knowledge of species diversity in more cryptic stomatopod superfamilies, such as Lysiosquilloidea.

Revision of the genus Niphta (Diptera, Thaumaleidae) Theischinger of South America, with descriptions of nine new species and a new immature morphotype.

The Niphta Theischinger fauna of South America is revised to include 11 species, nine of which are described as new to science (N.acus Pivar, sp. nov., N.bifurcata Pivar & Moulton, sp. nov., N.bispinosa Pivar & Sinclair, sp. nov., N.brunnea Pivar, sp. nov., N.courtneyi Pivar, sp. nov., N.daniellae Pivar, sp. nov., N.downesi Pivar, sp. nov., N.eurydactyla Pivar, sp. nov., N.mapuche Pivar, sp. nov.). The genus Niphta is redefined, both previously described Chilean species are redescribed, N.halteralis (Edwards) and N.nudipennis (Edwards), and females are described or redescribed where possible. The first descriptions of the immature stages of South American Niphta are provided, which represent a new larval morphotype in Thaumaleidae, as larvae and pupae possess ventral adhesive structures. Furthermore, these larvae were collected from vegetation rather than rocky substrates. Illustrations and micrographs are provided for all species, and scanning electron microscopy images are included for select immatures. A key to species, distribution maps, and discussions regarding phylogenetic affinities and habitat are also included.

Signals from the deep-sea: Genetic structure, morphometric analysis, and ecological implications of Cyclothone braueri (Pisces, Gonostomatidae) early life stages in the Central Mediterranean Sea

Cyclothone braueri (Stomiiformes, Gonostomatidae) is a widely distributed fish inhabiting the mesopelagic zone of marine tropical and temperate waters. Constituting one of the largest biomasses of the ocean, C. braueri is a key element in most of the ecological processes occurring in the twilight layer. We focused on the ecological processes linked to early life stages in relation to marine pelagic environmental drivers (temperature, salinity, food availability and geostrophic currents) considering different regions of the Central Mediterranean Sea. A multivariate morphometric analysis was carried out using six parameters with the aim of discerning different larval morphotypes, while a fragment of 367 bp representing the 12S ribosomal RNA gene was used to perform molecular analyses aimed at determining the intraspecific genetic variability. Analysis highlighted two geographically distinct morphotypes not genetically discernible and related to the different nutritional conditions due to spatial heterogeneities in terms of temperature and food availability. The body depth (BD) emerged as an appropriate morphometric parameter to detect the larval condition in this species. Molecular analysis highlighted a moderate genetic divergence in the fish population, showing the recurrence of two phylogroups not geographically separated.

Seasonal dynamics of meroplankton in a sub-Antarctic fjord (Southern Patagonia, Chile)

Knowledge of seasonal dynamics and composition of meroplankton (larvae of benthic invertebrates) is rather limited for sub-Antarctic regions. We studied the seasonal dynamics of meroplankton in a sub-Antarctic proglacial basin (Gallegos Sound, Chile), by examining changes in the meroplankton community in relation to hydrographic variables along four sampling cruises between early winter 2010 and late winter 2011. The local meroplankton community was composed of 39 larval morphotypes distributed among 11 major taxa, being polychaetes the best represented (15 larvae morphotypes), and bivalve the most abundant. We found distinct seasonal differences in terms of meroplanktonic composition and abundance, with higher abundance and larval morphotype number during austral spring and late winter, and lower in summer and early winter. The pattern observed for meroplankton was directly related to seasonal variations of fluorescence of chlorophyll a and temperature. We found meroplankton abundances lower than those of other sub- and Polar environments. However, meroplanktonic temporal dynamics showed a common pattern for sub- and Polar fjords, suggesting a strong link between benthic spawning and the occurrence of phytoplankton blooms.

DNA barcoding and taxonomic validation ofCaranxspp. larvae

AbstractOf the five nominal species in the genusCaranxLacepède 1801 distributed throughout the Eastern Central Pacific,Caranx caballusandCaranx sexfasciatusare the only two that have formal fish larval descriptions based on diagnostic characteristics (morphology, meristics and pigmentation). In this study, the diagnostic characteristics of threeCaranxspecies larvae were validated using DNA barcoding analysis cytochromecoxidase subunit I (COI; 651 bp). For the first time, the morphological taxonomic assignation ofC. caballusfish larvae was confirmed using COI gene partial sequences of adults, with a genetic similarity between 99.8–100%. However, molecular evidence demonstrated that fish larvae previously described asC. sexfasciatushad high genetic similarity (99.7–100%) and low genetic distance (<1%) toCaranx caninusadults. An undescribed larval morphotype collected in the present study genetically matched (100%) with COI sequences ofC. sexfasciatusadults. The diagnostic characteristics of this new morphotype were a lack of pigmentation in the supraoccipital crest, over the gut, and at the terminal region of the gut. The combination of diagnostic characteristics and DNA barcoding evidence allowed the discrimination and validation ofC. caballus,C. caninusandC. sexfasciatuslarvae. The diagnostic characteristics and COI sequences ofCaranx lugubrisandCaranx melampyguslarvae, which are also distributed in the Eastern Central Pacific, remain to be investigated.

Geographic variation in shape and size of anuran tadpoles: Interpopulation comparisons in Scinax fuscovarius (Anura, Hylidae)

Among anuran species with biphasic life cycle, the occurrence of intraspecific larval morphotypes has been related to variations in developmental time, diet, geographical variation, or response to predators. Here, we evaluated the external morphological variation of larvae among three populations, located more than 270 km apart, of the anuran hylid Scinax fuscovarius by linear and geometric methods, to elucidate the presence of geographically different morphs. Comparisons targeted development, growth, and external morphology. Studied populations exhibited differences in reproductive seasonality, growth rate, timing of development, shape, and size. Shape and size comparisons revealed two well-differentiated morphs, one of them shared by the two closest populations. Morphological differences evidenced a smaller and depressed form of the entire body plan in the most distant population, which showed continuous reproduction throughout the rainy season and under more unpredictable conditions. We interpret the occurrence of the two different larval morphs in S. fuscovarius as a by-product of local geographical conditions, and discuss on possible associations with biotic and abiotic factors cues.

A tholichthys‐like larva (Teleostei, Percomorpha) from the Eocene of Northern Caucasus, Russia

A morphologically bizarre fish larva is described based on a single specimen from Eocene (Bartonian) locality of Gornyi Luch, Krasnodar Region, Northern Caucasus, SW Russia. The fossil larva described here was collected form the Kuma Horizon and inhabited an open marine setting with bottom waters characterized by poorly oxygenated conditions, where it was associated with abundant pelagic fish taxa. This fossil fish larva exhibits a peculiar morphology, being characterized by remarkably expanded and thickened bones that form an armour-like protective covering, a strong and greatly elongate pelvic-fin spine and a unique head spination that comprises a conical and posterodorsally directed supraoccipital spine, a rostral spine formed by the nasals, and enormous spines on the preopercle and opercle. Moreover, this fish larva has an advanced insertion of the dorsal fin and 17 principal rays in the caudal fin thereby revealing its affinity to percomorph fishes. The hypertrophied bony plates encasing the head and forming a bony armour are shared with the so-called tholichthys larval stage of chaetodontid butterflyfishes, as well as with the larval stages of some other percomorphs. Comparison with selected percomorph larval morphotypes (e.g. families Chaetodontidae, Malacanthidae, Ostracoberycidae and Scatophagidae) suggests that the Eocene larva described herein exhibits a unique combination of characters that would support an attribution to a new, previously undescribed taxon.

Phylogeny, systematics and rarity assessment of New Zealand endemic Saphydrus beetles and related enigmatic larvae (Coleoptera : Hydrophilidae : Cylominae)

The New Zealand endemic beetle genus Saphydrus Sharp, 1884 (Coleoptera:Hydrophilidae:Cylominae) is studied in order to understand its phylogenetic position, species-level systematics, biology and distribution, and to reveal reasons for its rarity. The first complete genus-level phylogeny of Cylominae based on two mitochondrial (cox1, 16S) and two nuclear genes (18S, 28S) covering 18 of 19 genera of the subfamily reveals Saphydrus as an isolated lineage situated in a clade with Cylorygmus (South America), Relictorygmus (South Africa) and Eurygmus (Australia). DNA is used to associate two larval morphotypes with Saphydrus: one of them represents the larvae of S. suffusus Sharp, 1884; the other, characterised by unique characters of the head and prothorax morphology, is revealed as sister but not closely related to Saphydrus. It is described here as Enigmahydrus, gen. nov. with a single species, E. larvalis, sp. nov., whose adult stage remains unknown. Saphydrus includes five species, two of which (S. moeldnerae, sp. nov. and S. tanemahuta, sp. nov.) are described as new. Larvae of Enigmahydrus larvalis and Saphydrus suffusus are described and illustrated in detail based on DNA-identified specimens. Candidate larvae for Saphydrus obesus Sharp, 1884 and S. tanemahuta are illustrated and diagnosed. Specimen data are used to evaluate the range, altitudinal distribution, seasonality and population dynamics over time for all species. Strongly seasonal occurrence of adults combined with other factors (winter occurrence in S. obesus, occurrence at high altitudes in S. tanemahuta) is hypothesised as the primary reason of the rarity for Saphydrus species. By contrast, Enigmahydrus larvalis underwent a strong decline in population number and size since the 1970s and is currently known from a single, locally limited population; we propose the ‘nationally threatened’ status for this species. http://zoobank.org/urn:lsid:zoobank.org:pub:28D87163-29E8-418C-9380-262D3038023A

Fly palaeo-evo-devo: immature stages of bibionomorphan dipterans in Baltic and Bitterfeld amber.

Larvae of flies and gnats (Diptera) form a crucial component of many terrestrial and freshwater ecosystems in the extant biosphere. Larvae of Diptera play a central role in water purification, matter and energy transfer in riparian ecosystems in rivers, carbon cycling in lakes and forests as well as being major decomposers of dead organic matter. Despite all these important roles, dipteran larvae are most often ignored in palaeoecological studies, due to the difficulty of the taxonomic identification of fossil larvae, but also due to the perceived importance of adult dipterans in palaeoentomological and taxonomic studies. Despite that, much information on palaeoecosystems can be gained from studying fossil dipteran larvae, in particular for well preserved specimens from fossil resins (ambers and copals). Since ambers are selectively preserving fauna of trunks and leaf litter, it allows us to learn a lot about xylophages and saprophages of amber forests, such as Eocene Baltic amber forest. Here we present immature stages (larvae and pupae) of the dipteran ingroup Bibionomorpha, from Baltic and Bitterfeld amber forests. We have recorded at least four different larval morphotypes, one with four distinct instars, and at least three pupal morphotypes. One larva is recognised as a new species and can be interpreted either as a representative of a highly derived ingroup of Bibionidae or as a sister species to Bibionidae. Also represented by single larval specimens are the groups Pachyneura (Pachyneuridae) and Sylvicola (Anisopodidae). The majority of the recorded specimens are representatives of the group Mycetobia (Anisopodidae). Due to the abundance of immature stages of Mycetobia, we have been able to reconstruct the number of larval stages (4) and relative growth rate of these fossil dipterans. We discuss implications of these finds.

Taxonomic study of the genus Araucanioperla Illies 1963 (Plecoptera: Gripopterygidae), with the description of the male genitalia,eggs and the last instar larva for A. brincki.

A comparative study of morphology on the genus Araucanioperla Illies, 1963 is discussed. Two species of Araucanioperla are known, A. bullocki (Navás, 1933) and A. brincki (Froehlich, 1960). For the first time the larva of A. brincki, the male genitalia of A. bullocki and the eggs of the two species are described and illustrated. The results showed that the morphology of the larvae is similar for the genus, definitively rejecting other larval morphotypes proposed for it. Eggs are also similar between the two species. The male genitalia of both species are specifically distinctive.

Acricotopus indet. morphotype incurvatus: Description and genetics of a new Orthocladiinae (Diptera: Chironomidae) larval morphotype from the Tibetan Plateau.

High mountain ranges such as the Tibetan Plateau with an average altitude above 4500m are topographically complex formations. Elevational gradients, physiographic diversity and climatic heterogeneity have led to highly biodiverse ecosystems in these regions. Mountain ranges can be seen as cradles of evolution and harbour, due to their unique characteristics, a high number of highly adapted species. At the same time these areas are hard to access and therefore taxonomic information is limited. Here we describe a new Acricotopus (Diptera: Chironomidae: Orthocladiinae) larval morphotype occurring in lakes and ponds of differing salinity and water depths located on the Southern and Central Tibetan Plateau. The description is based on larvae and their genetics (ribosomal 18S, 28S and mitochondrial COI sequences) collected from a shallow pond in close proximity to the large saline lake Selin Co. Larvae of Acricotopus indet. morphotype incurvatus are characterized by a mentum with a cluster of lateral teeth, partially folded inwards, a mandible with a toothed lobe in addition to four inner teeth and a sclerotized plate positioned behind the mentum. Up to now, these morphological features have only been found in early instars of other Acricotopus species. The proposed morphotype name is inspired by the peculiar form of the mentum.

Woodlice and their parasitoid flies: revision of Isopoda (Crustacea, Oniscidea) - Rhinophoridae (Insecta, Diptera) interaction and first record of a parasitized Neotropical woodlouse species.

Terrestrial isopods are soil macroarthropods that have few known parasites and parasitoids. All known parasitoids are from the family Rhinophoridae (Insecta: Diptera). The present article reviews the known biology of Rhinophoridae flies and presents the first record of Rhinophoridae larvae on a Neotropical woodlouse species. We also compile and update all published interaction records. The Neotropical woodlouse Balloniscusglaber was parasitized by two different larval morphotypes of Rhinophoridae. Including this new record, there are 18 Isopoda species known to be parasitized and 13 Rhinophoridae species with known hosts, resulting in 35 interactions. There are a total of 53 interaction records from Holarctic and Neotropical countries. Of the 18 known isopod hosts, only five species have more than one parasitoid, including the new Neotropical host record presented in this work.

New and known zoonotic nematode larvae within selected fish species from Queensland waters in Australia

Zoonotic fish-borne nematodes are a significant and growing global health concern. However, in Australia their occurrence and geographical distribution are not well known. Moreton Bay in Queensland, Australia, is a popular tourist destination for domestic and international visitors where seafood is a popular food item. The aim of this study was to determine the occurrence of zoonotic nematodes within four commercially significant teleost fish species from Moreton Bay; Surf Bream, Sea Mullet, Yellow-Fin Tripod fish and Gold-Lined Sea Bream. Overall, 34.03% of fish examined (n = 144) were found to be a host to at least one parasitic nematode. The seasonal dynamics and prevalence of nematode infection was tested by statistical means. Results indicated a significant difference in seasonal infection for Surf Bream (p < 0.005) only. Several potentially zoonotic larval morphotypes were found, including Contracaecum types I and II, and Terranova type II (Family Anisakidae), and Hysterothylacium types VI and XIV and a new Hysterothylacium larval type herein assigned as type XVII (Family Raphidascarididae). ITS sequence data showed that some Contracaecum type II and Hysterothylacium types VI found in the present study are genetically distinct from those previously reported. The new genotypes were assigned to Contracaecum type II Genotype B and Hysterothylacium type VI, Genotypes B and C. This study provides essential information for future research on specific identification and differentiation of infective stages of zoonotic nematoda in edible fish.

Recognition and Distribution of Two North Atlantic Gadiculus Species, G. argenteus and G. thori (Gadidae), Based on Otolith Morphology, Larval Pigmentation, Molecular Evidence, Morphometrics and Meristics

The silvery pout genus Gadiculus consists of small aberrant codfishes with several extinct and currently only one recognized extant species. The oldest representatives of a Gadiculus lineage known from otoliths are Early Miocene in age. Fossil evidence has showed Gadiculus to originate from older genera diverging early from other true cods of the family Gadidae. As adult specimens of different species have been found to be highly similar and difficult to distinguish based on meristic and morphometric data, the number of species in this gadid genus has been controversial since different larval morphotypes were first discovered some 100 years ago. For almost 70 years, Gadiculus thori and Gadiculus argenteus have been considered subspecies only, with a distribution in the Northeast Atlantic Ocean including the Mediterranean. In this study, we resolve the long-standing issue of extant Gadiculus not being monotypic. New results in the form of distinct adult otoliths and molecular data unambiguously show two species of Gadiculus present—in agreement with larval morphotypes. Morphometric, meristic and molecular characters, as well as larval pigmentation are discussed in addition to present and past geographic distributions of the two taxa from distributions of fossil otoliths. At present, the cold-water species Gadiculus thori (northern silvery pout) is distributed in cold-temperate and subarctic latitudes in the Northeast Atlantic, including a new range extension off Southeast Greenland. Gadiculus argenteus (southern silvery pout) occurs in warmer waters and is distributed in the warm-temperate East Atlantic and Mediterranean. Fossil otoliths show that both species often co-existed in the Mediterranean from the Late Pliocene to the Middle Pleistocene.

Life History, Systematics and Evolution of the Diplostomoidea Poirier, 1886: Progress, Promises and Challenges Emerging From Molecular Studies.

Members of the Diplostomoidea mature in amniotes and employ vertebrates, annelids and molluscs as second intermediate hosts. Diplostomoid life cycles generally follow a three-host pattern typical of digeneans, but novelties have arisen in some species, including obligate four-host life cycles, vertical transmission, and intracellular parasitism. In this review, we summarize the basic biology of diplostomoids with reference to molecular studies, and present challenges, gaps and areas where molecular data could address long-standing questions. Our analysis of published studies revealed that most molecular surveys find more diplostomoid species than expected, but this tendency is influenced by how much effort goes into examining specimens morphologically and the number of sequenced worms. To date, molecular work has concentrated disproportionately on intraspecific or species-level diversity of larval stages in the Diplostomidae in temperate northern regions. Although the higher taxonomy of the superfamily is recognized to be in need of revision, little molecular work has been conducted at this level. Our phylogenetic analysis indicates several families and subfamilies require reconsideration, and that larval morphotypes are more reflective of evolutionary relationships than definitive hosts. The host associations of adult diplostomoids result from host-switching processes, whereas molecular surveys indicate that larval diplostomoid metacercariae have narrow ranges of second intermediate hosts, consistent with coevolution. Molecular dataare often used to link diplostomoid developmental stages, and we provide datafrom adult Neodiplostomum and Mesoophorodiplostomum that correct earlier misidentifications of their larval stagesand propose alternatives to collecting definitive hosts.

Bacterial communities of oceanic sea star (Asteroidea: Echinodermata) larvae

Planktotrophic sea star larvae of several species are abundant in oligotrophic waters of the Gulf Stream, western Sargasso Sea, and Caribbean Sea. One abundant larval morphotype at the bipinnaria stage of development is unusual in its ability to constitutively produce clones and in harboring a community of auto-fluorescent bacteria. We hypothesized that the bacterial community would be distinct in these larvae compared to those that do not consistently reproduce clonally. Three sea star larval morphotypes were collected in the Gulf Stream off the coast of Florida. We used DNA-based maximum likelihood phylogenetic analyses to taxonomically classify the larvae and 16S rDNA profiling by deep sequencing to characterize the bacterial communities harbored within. The cloning bipinnaria and non-cloning brachiolaria morphotypes were determined to be a single species of Asteroidea in the family Oreasteridae. The third morphotype, a non-cloning bipinnaria, was identified as Mithrodia clavigera. With bacterial 16S rDNA profiling, we found that the two species of larvae harbor bacterial communities distinct from each other. The Oreasteridae bacterial community at both developmental stages has a photosynthetic Cyanobacteria Synechococcus sp. as the most abundant bacteria. The M. clavigera larvae host a flora consisting primarily of Gammaproteobacteria. The identification of the larval microbiomes is a step toward understanding their host–microbe interactions. Specifically, the association of photosynthetic bacteria with cloning larvae allows for future assessments of whether the bacteria supplement the nutrition of the larvae during extended periods of development and clonal reproduction in open ocean regions where phytoplankton food for the larvae may be in limited supply.