Increasing the impact of vertebrate scientific collections through 3D imaging: The openVertebrate (oVert) Thematic Collections Network.

The impact of preserved museum specimens is transforming and increasing by three-dimensional (3D) imaging that creates high-fidelity online digital specimens. Through examples from the openVertebrate (oVert) Thematic Collections Network, we describe how we created a digitization community dedicated to the shared vision of making 3D data of specimens available and the impact of these data on a broad audience of scientists, students, teachers, artists, and more. High-fidelity digital 3D models allow people from multiple communities to simultaneously access and use scientific specimens. Based on our multiyear, multi-institution project, we identify significant technological and social hurdles that remain for fully realizing the potential impact of digital 3D specimens.

Interrelationships and biogeography of the New World pufferfish genus Sphoeroides (Tetraodontiformes: Tetraodontidae) inferred using ultra-conserved DNA elements.

Colonization of the New World by marine taxa has been hypothesized to have occurred through the Tethys Sea or by crossing the East Pacific Barrier. To better understand patterns and timing of diversification, geological events can be coupled with time calibrated phylogenetic hypotheses to infer major drivers of diversification. Phylogenetic relationships among members of Sphoeroides, a genus of four toothed pufferfishes (Tetraodontiformes: Tetraodontidae) which are found nearly exclusively in the New World (eastern Pacific and western Atlantic), were reconstructed using sequences from ultra-conserved DNA elements, nuclear markers with clear homology among many vertebrate taxa. Hypotheses derived from concatenated maximum-likelihood and species tree summary methods support a paraphyletic Sphoeroides, with Colomesus deeply nested within the genus. Analyses also revealed S. pachygaster, a pelagic species with a cosmopolitan distribution, as the sister taxon to the remainder of Sphoeroides and recovered distinct lineages within S. pachygaster, indicating that this cosmopolitan species may represent a species complex. Ancestral range reconstruction may suggest the genus colonized the New World through the eastern Pacific before diversifying in the western Atlantic, though date estimates for these events are uncertain due to the lack of reliable fossil record for the genus.

The larval attachment organ of the bowfin Amia ocellicauda Richardson, 1836 (Amiiformes: Amiidae) and its phylogenetic significance.

Larval attachment organs (LAOs) are unicellular or multicellular organs that enable the larvae of many actinopterygian fishes to adhere to a substrate before yolk-sac absorption and the free-swimming stage. Bowfins (Amiiformes) exhibit a sizable LAO on the snout, which was first described in the late 19th and early 20th centuries. In this study, we document the LAO of Amia ocellicauda (Richardson, 1836) using a combination of scanning electron microscopy (SEM) and light microscopy, and histochemistry. We examined material representing three stages with SEM ranging in size from 5.8 to 11.2 mm in notochord length and one stage histochemically. We compare the LAO of A. ocellicauda to that of the lepisosteid Atractosteus tropicus Gill, 1863 and show that although the LAOs of A. ocellicauda and A. tropicus are both super-organs, the two differ in the ultrastructure of the entire organ. A. ocellicauda possesses two distinct lobes, with the organs arranged on the periphery with none in the middle, whereas A. tropicus also possesses two lobes, but with the organs scattered evenly across the super-organ. The individual organs of A. ocellicauda possess adhesive cells set deep to support cells with the adhesive substance released through a pore, whereas A. tropicus possesses both support cells and adhesive cells sitting at a similar level, with the adhesive substance released directly onto the surface of the organ. We additionally provide a table summarizing vertebrate genera in which attachment organs have been documented and discuss the implications of our study for hypotheses of the homology of attachment organs in the Holostei.

Acoustic and postural displays in a miniature and transparent teleost fish, Danionella dracula.

Acoustic behavior is widespread across vertebrates, including fishes. We report robust acoustic displays during aggressive interactions for a laboratory colony of Danionella dracula, a miniature and transparent species of teleost fish closely related to zebrafish (Danio rerio), which are hypothesized to be sonic based on the presence of a hypertrophied muscle associated with the male swim bladder. Males produce bursts of pulsatile sounds and a distinct postural display - extension of a hypertrophied lower jaw, a morphological trait not present in other Danionella species - during aggressive but not courtship interactions. Females show no evidence of sound production or jaw extension in such contexts. Novel pairs of size-matched or -mismatched males were combined in resident-intruder assays where sound production and jaw extension could be linked to individuals. In both dyad contexts, resident males produced significantly more sound pulses than intruders. During heightened sonic activity, the majority of the highest sound producers also showed increased jaw extension. Residents extended their jaw more than intruders in size-matched but not -mismatched contexts. Larger males in size-mismatched dyads produced more sounds and jaw extensions compared with their smaller counterparts, and sounds and jaw extensions increased with increasing absolute body size. These studies establish D. dracula as a sonic species that modulates putatively acoustic and postural displays during aggressive interactions based on residency and body size, providing a foundation for further investigating the role of multimodal displays in a new model clade for neurogenomic and neuroimaging studies of aggression, courtship and other social interactions.

Three scleral ossicles in the West African Denticle herring Denticeps clupeoides (Clupeiformes: Denticipitidae).

The eyes of teleostean fishes typically exhibit two ossifications, the anterior and posterior sclerotics, both associated with the scleral cartilage. The West African Denticle herring Denticeps clupeoides has three scleral ossifications, including the typical two associated with the scleral cartilage (anterior and posterior sclerotic) and a third ossification (Di Dario's ossicle), spatially separated from the scleral cartilage and located within the anteromedial wall of the sclera. The medial rectus muscle inserts on the medial surface of Di Dario's ossicle, suggesting that this third sclerotic may play a role in forward rotation of the eye in this surface feeding fish.

Extreme evolutionary shifts in developmental timing establish the miniature Danionella as a novel model in the neurosciences.

BACKGROUND: Species of Danionella rank among the smallest of all vertebrates and their miniature size is correlated with an extreme case of progenesis, resulting in tiny, transparent sexually mature individuals. Progenesis has affected the entire skeleton of Danionella, in which 60 skeletal elements are absent, including some of the skull roofing bones. This lack of a skull roof combined with the presence of a fully formed hearing and sound producing apparatus has led to Danionella being used as an important model for neurophysiological studies. RESULTS: Using both rank based and PGi analyses we investigate sequence heterochrony in the development of the skeleton of Danionella dracula and close relatives. Extreme heterochronic shifts affect the appearance of bony elements in Danionella dracula. This includes a delay in the appearance of most chondral skull bones, and a reduction or loss of dermal bones that would otherwise form the skull roof. In contrast, formation of the anterior region of the vertebral column, including the functionally important elements of the Weberian apparatus, is greatly accelerated. CONCLUSIONS: Here we show that the anatomical conditions that favor Danionella for brain research are the result of extreme heterochronic shifts that have acted differentially across the skeleton.

The larval attachment organ of the tropical gar Atractosteus tropicus Gill, 1863 (Lepisosteiformes: Lepisosteidae).

Larval attachment organs (LAOs) are unicellular or multicellular organs that allow larvae to adhere to a substrate before yolk-sac absorption and the free-swimming stage. This study documents the LAO of tropical gar, Atractosteus tropicus, using a combination of scanning electron microscopy and light microscopy. It is shown that the LAO of A. tropicus is a super-organ surrounded by a wall and containing at its centre many smaller multicellular organ units, each comprised of attachment and support cells. Attachment cells are secretory and house large vacuoles filled with a glycoprotein. At hatching, the super-organ is well developed and occupies almost the entire anteroventral surface of the head. During subsequent development, the smaller individual units begin to regress, until at 6 days post-hatching the super-organ and its individual units are no longer visible.

Molecular systematics of the New World clingfish genus Gobiesox (Teleostei: Gobiesocidae) and the origin of a freshwater clade.

The phylogenetic relationships between marine and freshwater members of the New World clingfish genus Gobiesox are investigated using both mitochondrial and nuclear sequence data. Phylogenetic hypotheses are derived from Bayesian and maximum parsimony analyses of a six-gene concatenated data set (2 mitochondrial and 4 nuclear markers; 4098bp). Gobiesox is paraphyletic, due to the inclusion of Pherallodiscus, in phylogenetic hypotheses resulting from all analyses and its two included species are reassigned to Gobiesox. Within the expanded genus Gobiesox, the freshwater species (G. cephalus, G. juradoensis, G. mexicanus and G. potamius) represent a monophyletic group that is nested inside of a paraphyletic marine group. Based on the monophyly of the freshwater clingfishes, a habitat transition from marine to freshwater is inferred to have occurred only once in the evolutionary history of the group (potentially in the mid-Miocene). Gobiesox is obtained as part of a larger clade of New World clingfishes, including also members of Acyrtops, Acyrtus, Arcos, Rimicola, Sicyases and Tomicodon equivalent to the subfamily Gobiesocinae. The phylogenetic hypotheses obtained are discussed briefly in relation to the two alternative classifications currently in use simultaneously for the Gobiesocidae. A rediagnosis and list of included species is provided for Gobiesox.

Molecular phylogenetics of New World searobins (Triglidae; Prionotinae).

Phylogenetic relationships among members of the New World searobin genera Bellator and Prionotus (Family Triglidae, Subfamily Prionotinae) and among other searobins in the families Triglidae and Peristediidae were investigated using both mitochondrial and nuclear DNA sequences. Phylogenetic hypotheses derived from maximum likelihood and Bayesian methodologies supported a monophyletic Prionotinae that included four well resolved clades of uncertain relationship; three contained species in the genus Prionotus and one contained species in the genus Bellator. Bellator was always recovered within the genus Prionotus, a result supported by post hoc model testing. Two nominal species of Prionotus (P. alatus and P. paralatus) were not recovered as exclusive lineages, suggesting the two may comprise a single species. Phylogenetic hypotheses also supported a monophyletic Triglidae but only if armored searobins (Family Peristediidae) were included. A robust morphological assessment is needed to further characterize relationships and suggest classification of clades within Prionotinae; for the time being we recommend that Bellator be considered a synonym of Prionotus. Relationships between armored searobins (Family Peristediidae) and searobins (Family Triglidae) and relationships within Triglidae also warrant further study.

Different on the inside: extreme swimbladder sexual dimorphism in the South Asian torrent minnows.

The swimbladder plays an important role in buoyancy regulation but is typically reduced or even absent in benthic freshwater fishes that inhabit fast flowing water. Here, we document, for the first time, a remarkable example of swimbladder sexual dimorphism in the highly rheophilic South Asian torrent minnows (Psilorhynchus). The male swimbladder is not only much larger than that of the female (up to five times the diameter and up to 98 times the volume in some cases), but is also structurally more complex, with multiple internal septa dividing it into smaller chambers. Males also exhibit a strange organ of unknown function or homology in association with the swimbladder that is absent in females. Extreme sexual dimorphism of non-gonadal internal organs is rare among vertebrates and the swimbladder sexual dimorphisms that we describe for Psilorhynchus are unique among fishes.

On Psilorhynchus sucatio and P. nudithoracicus, with the description of a new species of Psilorhynchus from northeastern India (Ostariophysi: Psilorhynchidae).

Psilorhynchus sucatio (Hamilton) is redescribed based on the examination of 462 specimens, 13-67 mm standard length (SL). Psilorhynchus nudithoracicus Tilak & Husain is redescribed based on the examination of 97 specimens, 10-68 mm SL. Psilorhynchus gracilis Rainboth is placed in the synonymy of P nudithoracicus. Psilorhynchus hamiltoni, a new species and a member of the P. balitora species group, is described from the Tista River in West Bengal, India. It is distinguished from all other members of the P. balitora species group by having a well-developed lateral stripe, 6-7 poorly developed saddles that do not make contact with the lateral blotches, 7-11 lateral blotches, 34-35 lateral line scales, 9+8-9 principal caudal-fin rays, 36 total vertebrae, and the ventral surface between paired fins with a broad rectangular scaleless patch. A key to the species groups of Psilorhynchus is also provided, as are revised diagnoses for the P. balitora and P. nudithoracicus species groups.

The Chirostyloidea of the Northeastern Pacific: Host Associations, Range Extensions and a New Species (Decapoda: Anomura).

Four species of chirostyloid squat lobsters, including a new species and a range extension are reported herein from California. Uroptychus nicoleae sp.nov. was collected on a black coral, Lillipathes sp. off San Clemente Island. It is characterized by a rostrum bearing 1 or 2 lateral teeth, the carapace having 5 lateral spines and a belt of 15 spinules on the anterior dorsal surface, and the dactyls of pereopods 2-5 are curved and bearing a continuous row of 6-8 teeth. The new species is morphologically similar to U. bellus of the southwestern Pacific. The color in life is red and pink. Uroptychus occidentalis is reported for the first time off California. The chirostyloids Sternostylus iaspis and S. perarmatus, which also occur off California, are shown in video still images from a remotely operated vehicle. They inhabit antipatharians and soft corals (Primnoidae) and are easily distinguished from species of Uroptychus by their elongate chelipeds and spinose carapaces. We provide northern range extensions for Uroptychus bellus, Sternostylus defensus and Heteroptychus galapagos collected off Costa Rica.

Molecular Systematics of Redband Trout from Genome-Wide DNA Sequencing Substantiates the Description of a New Taxon (Salmonidae: Oncorhynchus mykiss calisulat) from the McCloud River.

Rainbow Trout, Oncorhynchus mykiss, exhibit high levels of phenotypic diversity leading to the recognition of numerous subspecies. A major distinction among Rainbow Trout subspecies exists between Coastal Rainbow Trout (O. m. irideus), which occurs west of the Cascade and Sierra Nevada mountain ranges, and interior Redband Trout (O. mykiss sspp.), largely distributed to the east. Interior Redband Trout are composed of three primary lineages and can share various outward, anatomical or physiological characteristics that are often symplesiomorphies or examples of convergence. We examine high-throughput DNA sequence data from Sacramento Redband Trout O. m. stonei from the Upper Pit and Upper McCloud Rivers along with representatives of Rainbow Trout and Golden Trout lineages to clarify the composition and relationships of the Sacramento Redband Trout. We find O. m. stonei to be polyphyletic, divided between populations in the Pit River and the Upper McCloud River. Redband Trout obtained from the Pit River are most-closely related to Great Basin Redband Trout O. m. newberrii and to fish of the Warner Lakes Basin and Surprise Valley within the O. m. newberrii lineage. The type specimen of O. m. stonei, collected from the Lower McCloud River, is phenotypically similar to Great Basin Redband Trout. We find as well that the isolated populations of trout in the Upper McCloud River Basin represent a lineage of Rainbow Trout now restricted to that region, are monophyletic and are not most closely related to the interior Redband Trout lineages of O. m. newberrii or O. m. gairdnerii. Furthermore, they are not represented by the type specimens of O. m. stonei or O. m. shasta. Consequently, we formally describe the McCloud River Redband Trout O. mykiss calisulat, new subspecies.

Patterns of Phenotypic Evolution Associated with Marine/Freshwater Transitions in Fishes.

Evolutionary transitions between marine and freshwater ecosystems have occurred repeatedly throughout the phylogenetic history of fishes. The theory of ecological opportunity predicts that lineages that colonize species-poor regions will have greater potential for phenotypic diversification than lineages invading species-rich regions. Thus, transitions between marine and freshwaters may promote phenotypic diversification in trans-marine/freshwater fish clades. We used phylogenetic comparative methods to analyze body size data in nine major fish clades that have crossed the marine/freshwater boundary. We explored how habitat transitions, ecological opportunity, and community interactions influenced patterns of phenotypic diversity. Our analyses indicated that transitions between marine and freshwater habitats did not drive body size evolution, and there are few differences in body size between marine and freshwater lineages. We found that body size disparity in freshwater lineages is not correlated with the number of independent transitions to freshwaters. We found a positive correlation between body size disparity and overall species richness of a given area, and a negative correlation between body size disparity and diversity of closely related species. Our results indicate that the diversity of incumbent freshwater species does not restrict phenotypic diversification, but the diversity of closely related taxa can limit body size diversification. Ecological opportunity arising from colonization of novel habitats does not seem to have a major effect in the trajectory of body size evolution in trans-marine/freshwater clades. Moreover, competition with closely related taxa in freshwaters has a greater effect than competition with distantly related incumbent species.

The emerging vertebrate model species for neurophysiological studies is Danionella cerebrum, new species (Teleostei: Cyprinidae).

The four described species of Danionella are tiny, transparent fishes that mature at sizes between 10-15 mm, and represent some of the most extreme cases of vertebrate progenesis known to date. The miniature adult size and larval appearance of Danionella, combined with a diverse behavioral repertoire linked to sound production by males, have established Danionella as an important model for neurophysiological studies. The external similarity between the different species of Danionella has offered an important challenge to taxonomic identification using traditional external characters, leading to confusion over the identity of the model species. Using combined morphological and molecular taxonomic approaches, we show here that the most extensively studied species of Danionella is not D. translucida, but represents an undescribed species, D. cerebrum n. sp. that is externally almost identical to D. translucida, but differs trenchantly in several internal characters. Molecular analyses confirm the distinctiveness of D. cerebrum and D. translucida and suggest that the two species are not even sister taxa. Analysis of the evolution of sexual dimorphisms associated with the Weberian apparatus reveals significant increases in complexity from the simpler condition found in D. dracula, to most complex conditions in D. cerebrum, D. mirifica and D. translucida.

Spectacular morphological novelty in a miniature cyprinid fish, Danionella dracula n. sp.

Danionella dracula is a new species of sexually dimorphic, miniature and highly developmentally truncated cyprinid fish. Compared with its close relative, the zebrafish Danio rerio, it lacks 44 bones or parts thereof and represents one of the most developmentally truncated vertebrates. Absence of the majority of bones appears to be due to developmental truncation via terminal deletion. In contrast to these larval-like features, D. dracula also shows several hyperossifications. Uniquely, among carp-like fishes, male D. dracula have a series of long, pointed odontoid processes on the jaws greatly resembling the jaw dentition of teleosts with true teeth. The anterior-most process in each jaw is extended as a canine-like fang projecting through the epithelium. True jaw teeth are absent from all 3700 species of cypriniforms and were lost at least in the Upper Eocene. It remains to be investigated, however, whether the conserved pathways to regulate tooth development in cypriniforms have been used in D. dracula to form and pattern the odontoid processes. This new species represents a remarkable example linking progenetic paedomorphosis via heterochronic change in developmental timing to the evolution of morphological novelties.

A new species of the live-bearing fish genus Poeciliopsis from northern Mexico (Cyprinodontiformes, Poeciliidae).

Poeciliopsis jackschultzi sp. nov., is described based on seven specimens (17.9-26.7 mm SL) from the Río Concepción (also known as Río Magdalena), Sonora, Mexico. The new species belongs to the Leptorhaphis species group and can be distinguished from other members of this group by features of the skeleton and colouration. The new species is sympatric with P. occidentalis, a hybridogenetic all-female biotype P. monacha-occidentalis, and hybrids between P. monacha-occidentalis females and P. jackschultzi males. The distribution of P. jackschultzi is highly restricted, and the main habitat, spring-fed marshy streams and pools, is susceptible to loss and degradation in a desert environment with increasing human water demand.

Ontogeny of the catfish pectoral-fin spine (Teleostei: Siluriformes).

The characteristic and morphologically variable pectoral-fin spine of catfishes (order Siluriformes) has been well-investigated based on later developmental stages (juveniles and adults) but information on the earliest life stages are lacking. Here, we document the ontogeny of pectoral-fin spines in four siluroid (Ictalurus punctatus, Noturus gyrinus, Silurus glanis and Akysis vespa) and two loricarioid catfishes (Corydoras panda and Ancistrus sp.). To further our understanding of pectoral-fin spine development, we also examined adult and juvenile specimens representing 41 of the currently 43 recognized families of catfishes. Development of the pectoral-fin spine is similar in all catfishes and resembles the development of a typical soft fin ray. Fusion between hemitrichia of the anteriormost lepidotrichium occurs proximally first, forming the spine proper, with growth of the spine occurring through the subsequent fusion of developing distal hemitrichial segments that comprise the spurious ray. The variation of pectoral-fin spine morphology observed is largely attributed to the presence/absence of five traits, which either develop as part of the hemitrichial segments that are added to the distal tip of the spine during growth (distal rami, anterior/posterior serrae) or develop independent of these segments (denticuli and odontodes).

A new genus and two new species of miniature clingfishes from temperate southern Australia (Teleostei, Gobiesocidae).

A new genus and two new species of miniature clingfishes are described based on specimens collected from dense stands of macroalgae in intertidal and shallow subtidal areas along the coast of southern Australia. The new genus, Barryichthys, is distinguished from other genera of the Gobiesocidae by unique features of the adhesive disc, including elongate papillae in adhesive disc regions A and B, the reduction and/or loss of several elements of the cephalic lateral line canals, the lower gill arch skeleton, and the neurocranium, and by having two distinct types of pectoral-fin rays. Barryichthyshutchinsi is described based on 19 specimens (12.4-18.7 mm SL) from Western Australia and South Australia. Barryichthysalgicola is described based on 22 specimens (9.0-21.0 mm SL) from Victoria, New South Wales and Tasmania. The new species are distinguished from each other by characters of body and head shape, vertebral counts, and aspects of live colour pattern. The new genus shares several characters in common with Parvicrepis, another genus of miniature gobiesocids from southern Australia that also inhabits macroalgae habitats. The many reductions and novel characters of Barryichthys are discussed within the context of miniaturisation.

'On Psilorhynchus sucatio and P. nudithoracicus', the sequel: Unnecessary and unscientific names lead to rapid synonymization and taxonomic time wasting-A response to Arunachalam et al. (2018).

The Torrent minnows Psilorhynchus sucatio (Hamilton, 1822) and P. nudithoracicus Tilak Husain, 1980 are widespread throughout the Ganges-Brahmaputra drainage of India, Bangladesh and Nepal (Conway et al., 2013). Like many widespread species, P. sucatio and P. nudithoracicus exhibit high levels of variation in morphological traits (particularly colour pattern) across their respective ranges and both have been described on more than one occasion by different authors examining material obtained from different parts of their range and/or unaware of earlier works. The distinctive, long-snouted torrent minnow Psilorhynchus sucatio was described by Hamilton (1822: 347) based on material from "Northern Bengal" (no types known). David (1953) introduced the name P. sucatio damodarai for a "variety" (=subspecies; ICZN, 1999; art. 45.6.4) of P. sucatio from the Damodar River (Jharkhand and West Bengal) and Tilak Husain (1980) described the subspecies P. sucatio nudithoracicus based on material from Uttar Pradesh. In 1983, Rainboth described Psilorhynchus gracilis based on a smaller, more slender series of Psilorhynchus with a shorter snout than P. sucatio, collected in the tributaries of the Ganges and Brahmaptura rivers in northern Bangladesh. In 2013, Conway et al. argued that the names P. s. nudithoracicus and P. gracilis referred to the same species, placed the latter in the synonymy of the former, and elevated P. nudithoracicus to species status. As part of their redescription of P. sucatio and P. nudithoracicus, Conway et al. (2013) examined large series of specimens representing a range of body sizes (462 specimens of P. sucatio [13-67 mm SL] and 97 of P. nudithoracicus = [10-68 mm SL]), and encompassing almost the entire range of both species, provided multiple figures illustrating the important anatomical features of both species and, most importantly, provided clear diagnoses.