Facial and gill musculature of polynemid fishes,with notes on their possible relationships with sciaenids (Percomorphacea: Perciformes)

The Polynemidae is a family of primarily marine fishes with eight genera and 42 extant species. Many aspects of their morphology are largely unknown, with few reports about their osteology and barely any information on their myology. This paper describes and illustrates in detail all facial and branchial muscles of representative species of polynemids. Our analysis demonstrates the existence of several remarkable and previously unknown specializations in the polynemid musculature. The aponeurotic and completely independent origin of the pars promalaris of the adductor mandibulae is apparently unique among percomorphs. The differentiation of this section into lateral and medial subsections; the total separation of the promalaris from the retromalaris; the differentiation of the pars primordialis of the levator arcus palatini into external and internal subsections are also uncommon features of polynemids that are shared by sciaenids, thus supporting the hypothesis of a closer relationship between these families.     

Functional anatomy of the luring apparatus of the deep-sea ceratioid anglerfish <Emphasis Type="Italic">Cryptopsaras couesii</Emphasis> (Lophiiformes: Ceratiidae)

The osteology and myology of the illicial apparatus of Cryptopsaras couesii were examined in an effort to elucidate function. The apparatus consists of two bones, a tiny illicial bone, completely enveloped by tissue of the esca, and an extremely long supporting pterygiophore that lies within a deep groove on the dorsal surface of the head. The anterior end of the pterygiophore emerges on the tip of the snout from between the frontal bones, while the posterior end, encased in a dermal sheath when the illicial apparatus is retracted, emerges on the back just anterior to the dorsal caruncles. Five pairs of muscles control movement of the illicial apparatus: small, short erectors and depressors control movement of the illicial bone, while extremely long inclinators, protractors, and retractors control movement of the pterygiophore. The protractors and retractors of C. couesii are more robust and much longer than those of other lophiiforms, indicating that the pterygiophore of this species has an exceptionally wide range of movement in the anterior and posterior plane. Moreover, these muscles wind around the pterygiophore in opposite directions, a unique anatomy that suggests that C. couesii extends and retracts the pterygiophore by rotation.     

Phylogeny, evolution and biogeography of the Quadrifoliovariinae Yamaguti, 1965 (Digenea: Lecithasteridae)

The Quadrifoliovariinae is revised and three new species of Quadrifoliovarium Yamaguit, 1965 from acanthurid fishes of the genus Naso from waters of the Indo-Pacific are described: Q, maceria n. sp. from N.␣tonganus, N. annulatus, N. fageni and N. brevirostris; Q. simplex n. sp. from N. tonganus and N.␣annulatus; and Q. quattuordecim n. sp. from N. tonganus. Amendments are made to the characterisation of the Quadrifoliovariinae, Quadrifoliovarium, Bilacinia Manter, 1969 and Unilacinia Manter, 1969 in light of observations on type and new material. A molecular phylogeny based on ITS2 and 28S regions of the ribosomal DNA is proposed. The phylogeny suggests that U. asymmetrica is the most basal taxon and Q.␣simplex n. sp. and Q. quattuordecim n. sp. the most derived. Evolution of morphological traits within the Quadrifoliovariinae are discussed in light of the molecular phylogeny. Molecular sequences of the ITS2 rDNA were identical between specimens of Q. pritchardae collected off Exmouth (Indian Ocean), Heron Island and Lizard Island (Western Pacific) and Moorea (far Eastern Indo-Pacific), indicating a broad Indo-Pacific distribution. All members of the subfamily are recorded only from the acanthurid genus Naso, with the exception of B. lobatum (Yamaguti, 1970), which has been recorded from a pomacanthid. The restricted host range of the group is discussed in the light of the phylogeny of the host genus Naso.     

The pectoral anatomy of selected Ostariophysi. II. The Cypriniformes and siluriformes

The pectoral myology and osteology of the cyprinoids Notemigonus crysoleucas, the golden shiner, and Catostomus commersonnii, the common white sucker, resemble those of generalized, lower teleosts in structure and function, except in features related to the manipulation of the massive fifth ceratobranchial of cyprinoids by muscles attaching on the girdle. Catostomus is more specialized in having unique intercostal muscles to the girdle, complex subclavian arteries and lack of a superficial trapezius muscle. The bony pectoral anatomy of the siluriform, Ictalurus nebulosus, the brown bullhead, is highly specialized in relation to the presence and locking of the massive pectoral spine which is formed of fused dorsal and ventral propterygial rays; there is consolidation of the girdle through fusion of bones, presence of unique stabilizing bony structures, firm symphyseal union of bilateral girdles and the presence of friction-surfaces of girdle and spine for locking. The movements of the spine are specialized in the greater guidance offered by the girdle. Myological specializations are related mainly to ventral appendicular muscles which lock the spine. The nervous and arterial systems are generalized.     

Using the whole body as a sucker: Combining respiration and feeding with an attached lifestyle in hill stream loaches (Balitoridae,Cypriniformes)

Small fishes living in fast‐flowing rivers face a harsh environment as they can easily be swept away by the rapid currents. To survive such circumstances, teleosts evolved a wide variety of attachment mechanisms, based on friction, negative pressure or both. Balitorinae (Balitoridae, Cypriniformes) are exceptional in using their whole body as an adhesive apparatus. We investigated the morphological adaptations of Balitorinae by studying the osteology and myology of four species (Beaufortia leveretti, Sewellia lineolata, Pseudogastromyzon myersi, and Gastromyzon punctulatus) using clearing and staining, serial cross‐sections and CT‐scanning. A kinematic analysis was performed to study the respiration and feeding mechanisms and to identify key structures in these mechanisms. Our research showed that the whole body of Balitorinae acts as a suction disc, with friction‐enhancing structures (unculi) on the thickened anterior rays of the paired fins. The abruptly rising head profile, supported by the extremely enlarged lacrimal bone and the flat ventral body surface facilitate effective substrate attachment. During attachment, the pelvic girdle is pulled anterodorsally, suggesting the formation of a negative pressure underneath the body. Detachment by water inflow underneath the body is prevented by three mechanisms. 1) Barbels control the water inflow by detachment and reattachment to the substrate. 2) Most water present underneath the body is removed during inspiration. 3) Excess water is regularly removed by movements of the posterior pectoral fin rays. The balitorine body is thus modified as such that it allows effective attachment, while not impairing respiration. Comparison with other teleosts living in similar environments shows that most species use more locally concentrated modifications of the paired fins and/or the mouth for attachment. The high diversity in teleostean adhesive apparatuses and associated myological modifications suggest a substantial functional convergent evolution, without necessarily highly convergent anatomical adaptations. J. Morphol. 275:1066–1079, 2014. © 2014 Wiley Periodicals, Inc.     

Osteology and cranial musculature of Caiman latirostris (crocodylia: Alligatoridae)

Caiman latirostris Daudin is one of the extant species of Caimaninae alligatorids characterized taxonomically only by external morphological features. In the present contribution, we describe the cranial osteology and myology of this species and its morphological variation. Several skull dissections and comparisons with other caimans were made. Although jaw muscles of living crocodiles show the same general “Bauplan” and alligatorids seem to have a similar cranial musculature pattern, we describe some morphological variations (e.g., in C. latirostris the superficial portion of the M. adductor mandibulae externus did not reach the postorbital; the M. adductor mandibulae internus pars pterygoideus dorsalis did not reach the pterygoid and lacrimal and contrary to the case of C. crocodilus the M. adductor mandibulae internus pars pterygoideus ventralis attaches to the posterodorsal surface of the pterygoid and the pterygoid aponeurosis, without contacting the dorsal and ventral surface of the pterygoid margin; the M. intermandibularis is attached to the anterior half of the splenial and posteriorly inserts medially by a medial raphe that serves as attachment zone for M. constrictor colli, and the M. constrictor colli profundus presents a medial notch in its anterior margin). In addition, the skull of C. latirostris differs from that of other caimans and possesses several characters that are potential diagnostic features of this species (e.g., outline of glenoid cavity in dorsal view, extension of the rostral ridges, and occlusion of the first dentary tooth). Nevertheless, these characters should be analyzed within the phylogenetic context of the Caimaninae to evaluate its evolutionary implications for the history of the group. J. Morphol. 2011. © 2011 Wiley‐Liss, Inc.     

Atavisms and the homology of hyobranchial elements in lower vertebrates

The homology of branchial arch segments in salamanders has been a matter of controversy since the last century. Many investigators term the most medial paired elements of salamander branchial arches “ceratobranchials” and the next distal paired elements “epibranchials.” This suggests that the first two segmental elements of the salamander branchial arch are not homologous with elements occupying the same position in ray-finned fishes, Latimeria, “rhipidistians,” and lungfishes, in which these bones are called hypobranchials and ceratobranchials, respectively. Three lines of evidence suggest that it is more parsimonious to interpret urodele branchial arch segments as being homologous with those of other vertebrate clades?(1) comparative osteology, (2) comparative myology, and (3) the discovery of cartilaginous structures forming a third segmental unit that we interpret as atavistic epibranchials of the branchial arch in one population of the salamander Notophthalmus viridescens. These structures possess all the defining attributes of atavisms, and illustrate the special role that atavistic features play in resolving questions of homology recognition.     

Nontroglobitic Fishes in Bruffey-Hills Creek Cave, West Virginia, and other Caves Worldwide

Six species of fishes were tagged and released in September and November 1995 and on five dates between November 1998 and October 1999 inside Bruffey-Hills Creek Cave. Most of the tagged fishes were creek chub, Semotilus atromaculatus, and green sunfish, Lepomis cyanellus. The overall recapture rate was 2.6% as only three of 117 fishes were recaptured. Forty-nine days was the longest time of residence by two L. cyanellus and one S. atromaculatus, and movement of 83.4 m was observed only for the creek chub. Tag loss was confirmed as one factor in the low recapture rate. Nine species of fishes were collected in the cave, including Phoxinus oreas and Pimephales promelas, two species never collected in a cave. Most of the fishes were pigmented normally, but many creek chubs were depigmented and appeared white or pigmentless when first observed in the cave stream. Four species, Phoxinus oreas, Pimephales promelas, Ameiurus nebulosus, and Lepomis macrochirus, were collected for the first time in Bruffey-Hills Creek Cave and in the Bruffey and Hills creeks drainage. Although data from this study did not shed light on residence time of fishes in the cave, the consistent occurrence of epigean fishes in this cave was shown. A list of epigean fishes from caves worldwide was included along with a discussion of aspects of the ecology of epigean fishes in caves and of evolution of troglobitic fishes.     

Kinematics and functional morphology of aquatic feeding in Australian snake-necked turtles (Pleurodira; Chelodina)

Head kinematics during aquatic feeding of the Australian long-necked turtle (Chelodina) were studied by means of high speed video recordings. Buccal expansion was assessed by calculation of elliptical cross-sectional surfaces. Further, displacements of head, carapace, and prey in the earth bound frame, of the prey relative to the center of the gape, and of the head relative to the carapace were determined. Rates of change (velocities) of all these variables were calculated. These data are combined with information on the osteology and myology of the head. The robust development of the large hyobranchial apparatus, the massive intercornuatus muscle, and the presence of the branchiosquamosus muscle were related to aquatic feeding skills. Head kinematics are variable in amplitude and relative timing, but proceed always in a rostrocaudal sequence. According to their effect on the prey, two components are distinguished in the process of expansion. The first compensates for head/body movements (compensatory suction). The second causes distinct acceleration of water and prey (inertial suction). The latter component is mainly driven by the abduction of the second branchial arch. In spite of largely different structural solutions, optimal feeding conditions as deduced for suction in feeding fishes are also employed by Chelodina. This further promotes the assumption that hydrodynamics constrain evolutive solutions for aquatic feeding. J. Morphol. 233:113–125, 1997. © 1997 Wiley-Liss, Inc.     

Osteology and ontogeny of the wrymouths,genus Cryptacanthodes (Cottiformes: Zoarcoidei: Cryptacanthodidae)

The four species included in the family Cryptacanthodidae are eel‐like, burrowing fishes distributed in the cold‐temperate coastal waters of the North Pacific and the western North Atlantic. This study describes the osteology and aspects of the ontogenetic skeletal development of two species, Cryptacanthodes maculatus from the western North Atlantic and C. aleutensis from the eastern North Pacific. We discuss the relationships of Cryptacanthodidae among other zoarcoid families. The Cryptacanthodidae have been previously included in the Stichaeidae, but removed and classified as a separate family based on the skull, pectoral radial, and cephalic lateral‐line morphology. Our observations (similarities in gill arch and pectoral girdle morphology; specifically, a thin sheet‐like flange of bone from the posterior margin of the supracleithrum) suggest a close relationship to at least some of the members of the family Stichaeidae. J. Morphol. 276:185–208, 2015. © 2014 Wiley Periodicals, Inc.     

The hindlimb myology of Milvago chimango (Polyborinae,Falconidae)

We describe the hindlimb myology of Milvago chimango. This member of the Falconidae: Polyborinae is a generalist and opportunist that can jump and run down prey on the ground, unlike Falconinae that hunt birds in flight and kill them by striking with its talons. Due to differences in the locomotion habits between the subfamilies, we hypothesized differences in their hindlimb myology. Gross dissections showed that the myology of M. chimango is concordant with that described of other falconids, except for the following differences: the m. flexor cruris medialis has one belly with a longitudinal division; the m. iliotibialis lateralis does not have a connection with the m. iliofibularis; the m. fibularis longus is strongly aponeurotic; the m. tibialis cranialis lacks an accessory tendons and the m. flexor hallucis longus has one place of origin, instead of two. The presence of the m. flexor cruris lateralis can be distinguished as it has been described absent for the Falconidae. We associated its presence with the predominant terrestrial habit of the M. chimango. Each muscle dissected was weighed and the relationship between flexors and extensors at each joint was assessed. The extensor muscles predominated in all joints in M. chimango. Among the flexors, the m. flexor hallucis longus was the heaviest, which could be related to the importance of the use of its talons to obtain food. J. Morphol. 274:1191–1201, 2013. © 2013 Wiley Periodicals, Inc.     

Comparison of the oral cavity architecture in surgeonfishes (Acanthuridae, Teleostei), with emphasis on the taste buds and jaw “retention plates”

The present study summarizes observations on the skin plates (“retention plates”) and taste buds (TBs) in the oropharyngeal cavity (OC) of 15 species of surgeonfishes (Acanthuridae), all of which are predominantly herbivorous. Two phenomena mark the OC of these fishes: the presence of skin-plates rich in collagen bundles at the apex of the jaws, and cornified papillae on the surface. It is suggested that these plates help in retaining the sections of algae perforated at their base by the fishe’s denticulate teeth. The TBs, especially type I, are distributed across the buccal valves, palate and floor of the OC, forming species–specific groupings along ridges established by the network of sensory nerves. The number of TBs in the OC increases with growth of the fish up to a certain standard length, especially at the posterior part of the OC, and differs among the various species: e.g., Zebrasoma veliferum possesses 1420 TBs and Parcanthurus hepatus 3410. Species of Naso show a higher number of TBs than most species of Acanthurus, possibly connected with their more diversified diet. The pharyngeal region of these fishes is expanded through lowering the base of the gill-arches, and together with the occurrence of high numbers of TBs in this region, indicates the importance of the posterior region of the OC in herbivorous fishes for identification of the engulfed food particles prior to swallowing. The discussed observations shed light on the micro-evolutionary developments of the OC within the family Acanthuridae and contribute to the taxonomic characterization of the various species.     

Morphological and histochemical characterization of the pectoral fin muscle of batoids

Batoids differ from other elasmobranch fishes in that they possess dorsoventrally flattened bodies with enlarged muscled pectoral fins. Most batoids also swim using either of two modes of locomotion: undulation or oscillation of the pectoral fins. In other elasmobranchs (e.g., sharks), the main locomotory muscle is located in the axial myotome; in contrast, the main locomotory muscle in batoids is found in the enlarged pectoral fins. The pectoral fin muscles of sharks have a simple structure, confined to the base of the fin; however, little to no data are available on the more complex musculature within the pectoral fins of batoids. Understanding the types of fibers and their arrangement within the pectoral fins may elucidate how batoid fishes are able to utilize such unique swimming modes. In the present study, histochemical methods including succinate dehydrogenase (SDH) and immunofluoresence were used to determine the different fiber types comprising these muscles in three batoid species: Atlantic stingray (Dasyatis sabina), ocellate river stingray (Potamotrygon motoro) and cownose ray (Rhinoptera bonasus). All three species had muscles comprised of two muscle fiber types (slow-red and fast-white). The undulatory species, D. sabina and P. motoro, had a larger proportion of fast-white muscle fibers compared to the oscillatory species, R. bonasus. The muscle fiber sizes were similar between each species, though generally smaller compared to the axial musculature in other elasmobranch fishes. These results suggest that batoid locomotion can be distinguished using muscle fiber type proportions. Undulatory species are more benthic with fast-white fibers allowing them to contract their muscles quickly, as a possible means of escape from potential predators. Oscillatory species are pelagic and are known to migrate long distances with muscles using slow-red fibers to aid in sustained swimming.     

Morphological variation of hypaxial musculature in salamanders (Lissamphibia: Caudata)

Despite the acknowledged importance of the locomotory and respiratory functions associated with hypaxial musculature in salamanders, variation in gross morphology of this musculature has not been documented or evaluated within a phylogenetic or ecological context. In this study, we characterize and quantify the morphological variation of lateral hypaxial muscles using phylogenetically and ecologically diverse salamander species from eight families: Ambystomatidae (Ambystoma tigrinum), Amphiumidae (Amphiuma tridactylum), Cryptobranchidae (Cryptobranchus alleganiensis), Dicamptodontidae (Dicamptodon sp.), Plethodontidae (Gyrinophilus porphyriticus), Proteidae (Necturus maculosus), Salamandridae (Pachytriton sp.), and Sirenidae (Siren lacertina). For the lateral hypaxial musculature, we document 1) the presence or absence of muscle layers, 2) the muscle fiber angles of layers at mid‐trunk, and 3) the relative dorsoventral positions and cross‐sectional areas of muscle layers. Combinations of two, three, or four layers are observed. However, all species retain at least two layers with opposing fiber angles. The number of layers and the presence or absence of layers vary within species (Necturus maculosus and Siren lacertina), within genera (e.g., Triturus), and within families. No phylogenetic pattern in the number of layers can be detected with a family‐level phylogeny. Fiber angle variation of hypaxial muscles is considerable: fiber angles of the M. obliquus externus range from 20–80°; M. obliquus internus, 14–34°; M. transversus abdominis, 58–80° (acute angles measured relative to the horizontal septum). Hypaxial musculature comprises 17–37% of total trunk cross‐sectional area. Aquatic salamanders show relatively larger total cross‐sectional hypaxial area than salamanders that are primarily terrestrial. J. Morphol. 241:153–164, 1999. © 1999 Wiley‐Liss, Inc.     

Gelatinous zooplankton (ctenophores,salps and medusae): an important food resource of fishes in the temperate SW Atlantic Ocean

This study quantifies the occurrence of gelatinous zooplankton in the stomach contents of fishes from the southwest Atlantic Ocean (33°–55°S). More than 69,000 fish stomachs belonging to 107 species were examined. A total of 39 fishes were documented as consumers of gelatinous zooplankton, 23 of which were newly discovered. Three gelatinous organism consumption categories are recognized: (1) very frequent consumers (10 species, six of which were exclusive); frequent consumers (five species); and occasional consumers (26 species). Three types of gelatinous prey (ctenophores, salps and medusae) were found in the stomach contents of fishes. Ctenophores were consumed at high levels across almost the entire continental shelves of Argentina and Uruguay. Salps were frequent prey on the slope and southern shelf. In contrast, medusae were consumed in coastal areas, slopes and the southern shelf. Classification methods (group average sorting of the Bray–Curtis similarity measures based on log (X?+?1)-transformed percentage data) determined six areas where fishes predated on gelatinous organisms. SIMPER (similarity percentages) analysis determined which fishes contributed more to the consumption of gelatinous organisms. Results revealed that two fish species (Stromateus brasiliensis and Squalus acanthias) had high gelatinous zooplankton predation rates throughout the entire study area, while another six species (Patagonotothen ramsayi, Helicolenus dactylopterus lahillei, Macrourus holotrachys, Merluccius hubbsi, Schroederichthys bivius, and Macruronus magellanicus), while widely distributed, seemed to have specific areas where consumption occurred. This study not only provides new knowledge about the importance of gelatinous zooplankton in the diet of numerous fishes, but might also be valuable for planning and managing local fisheries.