Dorsal Pterygiophores Research Articles

A new crossognathiform fish (Teleostei: †Crossognathiformes) from San José de Gracia quarry reveals a great diversity in the Cretaceous outcrops of Mexico

We describe a new species, †Buapichthys gracilis gen. et sp. nov., based on two specimens from the Turonian deposits of the San José de Gracia quarry, Molcaxac, Puebla, central Mexico. Osteological features show this new species belongs to the order †Crossognathiformes, nesting within the suborder †Pachyrhizodontoidae. The combination of features, such as a slender body, the head with cephalic spines, three hypertrophied postcleithra, the pelvic fin posterior to the dorsal fin, the first and last dorsal pterygiophores modified into scutes, and the dorsal fin bony projections shows that †Buapichthys gracilis gen. et sp. nov. is different from other crossognathiform. This new taxon represents an increase in the group's diversity, constituting the seventh species of the order †Crossognathiformes reported in Mexico. Evaluating the crossognathiform biodiversity over time indicates that the great crossognathiform diversification occurred during the Albian until the Turonian. The Mexican fossil record significantly contributes to this diversity, with about 18% of the species recognized for this period.

Saddleback syndrome in the firemouth cichlid Thorichthys meeki (Cichliformes: Cichlidae) in Campeche, Mexico

There are several external and internal abnormalities that affect development in both wild and farmed fish. One of these abnormalities is known as saddleback syndrome (SBS), characterized by abnormalities in the shape, number, or absence of dorsal pterygiophores, causing a concavity in the dorsal region and absence of fin sections. The causes of this syndrome are not yet clear, but could be caused by fishing or predator damage, nutritional deficiencies, genetic conditions and environmental stress from pollutants that may cause alteration in the ontogenetic development of the fish. This study recorded for the first time the SBS in a wild-caught specimen of Thorichthys meeki Brind, 1918 (Cichlidae). Specimens were collected in the locality of Chekubul, municipality of Carmen, Campeche, México on November 18, 2022. The development of the dorsal fin begins from the first to the ninth dorsal spine where there is a dorsal concavity, which ends with the last three dorsal spines. There is no evidence of scoliosis or lordosis from the X-ray analysis; however, the dorsal pterygiophores show irregularities in their development. The specimen with the syndrome showed no other body abnormalities that would have prevented its development to adulthood, although the causative agent is unclear.

Patterns description of hyperostosis observed in Atlantic moonfish Selene setapinnis and lookdown Selene vomer.

Hyperostosis manifests itself and develops differently in taxonomically related species. Radiographic images of individuals belonging to different size classes of Atlantic Moonfish Selene setapinnis and Lookdown Selene vomer were obtained from two different estuarine areas of Rio de Janeiro/Brazil. In S. setapinnis, hyperostosis occurred in 65.22% of the specimens analyzed in three different skeletal regions. All specimens of S. vomer had hyperostosis in four regions. Patterns of occurrence were detected in both species, and the affected regions did not coincide in the same bone region, except for the cleithrum. Hyperostosis in S. setapinnis were observed in high frequencies of seventh dorsal pterygiophore, whereas in specimens of S. vomer this condition was detected to a greater extent in the neural spines of the second abdominal vertebra and first to third caudal vertebrae. The data demonstrated a relationship between the sexual maturity and the occurrence and development of hyperostotic bones in ageing process of individuals. It is the first description of S. vomer with a hyperostosis phenomenon for the species on the Brazilian coast.

Revision of †Ellimmichthys longicostatus (Clupeomorpha: †Ellimmichthyiformes) from the Lower Cretaceous of Brazil with comments on the taxonomy of related species

†Ellimmichthys longicostatus is a deep-bodied and double-armored clupeomorph fish only known from non-marine Berriasian-Valanginian beds of the Recôncavo Basin, northeastern Brazil. It is the oldest herring-like fossil fish described from South America. This species was recently separated in two distinct forms that have not yet been formally classified: the first has the pelvic fin anterior to the origin of the dorsal fin, enlarged, thorn-shaped postpelvic scutes, posteriormost ribs on parapophyses, and long dorsal pterygiophores; the second one has the pelvic fin opposite the base of the dorsal fin and all the ribs inserted in deep excavations on centra. The latter corresponds to the fish used as a reference by Edward Drinker Cope, in 1886, in the original description of the species and herein referred as †Ellimmichthys longicostatus s. str. Consequently, the current diagnosis of †Ellimmichthys is not sufficient to distinguish species and closely related taxa. Based on new and old articulated specimens, we provide an amended diagnosis for †Ellimmichthys longicostatus s. str. and erect †Ellimmichthys spinosus nov. sp. for the rare form that was mistakenly identified to be the same species.

Early development and occurrence patterns of the Pagrinae seabream Argyrops bleekeri (Perciformes: Sparidae): Does early life history have implications for sparid relationships?

The early development and occurrence patterns of Argyrops bleekeri are described based on 87 specimens collected from Nakagusuku Bay on Okinawa Island in southwestern Japan. Larvae and juveniles of the genus Argyrops are distinguished from the other seabreams inhabiting the Western Pacific region by the strength and extent of head spination, body depth, dorsal-fin-ray counts and melanophore patterns. Argyrops bleekeri is easily distinguished from other members of this genus by the presence of a single rudimentary dorsal-fin spine on the first dorsal pterygiophore, melanophore patterns and an allopatric distribution. Argyrops bleekeri larvae [3.3-7.1 mm body length (BL)] and juveniles (6.7-13.0 mm BL) were found in the bay from January to May; nonetheless, they were not collected from the outer bay or in extremely shallow inshore areas such as tidal flats. The results suggest that Argyrops is the most derived red seabream because of its spiny morphology, and it may be a member of an expanding nearshore group of red seabreams, which originally inhabited offshore waters.

Burrowing fishes: Kinematics, morphology and phylogeny of sand-diving wrasses (Labridae).

Burrowing through the substrate is a common behaviour in many organisms, both invertebrate and vertebrate. Sand-diving, a burrowing behaviour in the fish family Labridae, consists of a quick and forceful headfirst plunge into the sediment followed by undulatory axial body movements until the fish is completely concealed beneath the surface. This study determined that sand-diving of the slippery dick wrasse Halichoeres bivittatus is composed of two distinct phases of undulatory axial body movements. In the first phase, body undulations occur at high frequencies and wave speeds and low amplitudes, while in the second phase, frequencies and wave speeds decrease while amplitude increases. Furthermore, this study examined several morphological features of sand-diving labrids, including narrow, elongated bodies and lengthened neural spines that overlap with the dorsal pterygiophores, that may be anatomical traits that contribute to burrowing ability. Finally, ancestral state reconstruction showed that sand-diving occurs exclusively in the upper half of the labrid phylogenetic tree with an evolutionary history indicating that sand-diving may have evolved once and then been lost three to five times or may have evolved independently at least three times in family Labridae.

Taxonomic review of the genus Argyrops (Perciformes; Sparidae) with three new species from the Indo-West Pacific.

The Indo-West Pacific sparid genus Argyrops is reviewed, with four valid species and three new species: A. bleekeri Oshi-ma, 1927, A. filamentosus (Valenciennes, 1830), A. megalommatus (Klunzinger, 1870), A. spinifer (Forsskål, 1775), A. caeruleops n. sp., A. flavops n. sp. and A. notialis n. sp. The above seven species can be differentiated on meristic values, ontogenetic and morphological characters, and coloration. Argyrops bleekeri from the western Pacific and A. notialis n. sp. from Western Australia both have only one rudimentary dorsal-fin spine on the first dorsal pterygiophore (which defines the Argyrops bleekeri complex), while the five other congeners have two rudimentary dorsal-fin spines, both associated with the first dorsal pterygiophore. Argyrops filamentosus, A. megalommatus, and A. caeruleops n. sp. have the 3rd dorsal-fin spine filamentous and longest, the defining character of the A. filamentosus complex. Argyrops spinifer (from the Indian Ocean) and A. flavops n. sp. (from the Middle East to Pakistan, but not the Red Sea and probably rare in the Persian Gulf) differ from other complexes in having 4-6 elongated or filamentous dorsal-fin spines (usually 3rd-6th [four spines] or 3rd-8th [six spines]) in juveniles and subadults, with the first 2 dorsal-fin spines rudimentary, the characteristic of the A. spinifer complex. The above three complexes include the seven Argyrops species that are defined and supported by morphological and color differences, genetic distinctions (partial cytochrome b genes, 1,116 bp), and distribution. The nominal species are discussed, together with several geographic variations of A. spinifer from the Indian Ocean, and a key to the species is provided.

Presence of repeating hyperostotic bones in dorsal pterygiophores of the oarfish, Regalecus russellii.

Hyperostosis, excessive bone growth along bone that stems from bone, periosteum or articular or epiphyseal cartilage, occurs in at least 22 families of fishes most of which are tropical or subtropical marine species. While the presence of hyperostosis is well documented in fishes, the mechanism driving the development of the excessive bone growth is unclear. This study documented hyperostosis along the dorsal pterygiophores in both sexes of oarfish, Regalecus russellii; however, it was not present in all specimens examined. This is the second lampridiform fish with hyperostoses and the first case documented in a deeper-water, epi-mesopelagic fish. In oarfish, the majority of the dorsal pterygiophores tissues are poorly mineralized, anosteocytic bones with some fish displaying localized stiffened, hyperostotic growths near the distal edge. Oarfish lack a swim bladder so they must continuously beat their bi-directional dorsal fin to maintain position within the water column while engaged in locomotory behavior. These fishes have areas of localized, hyperostotic skeletal elements along the dorsal pterygiophores that, presumably, function as a stiffened lever system to support fin undulation. It was noted that hyperossification was not present in all fish examined and was only documented in fish with total lengths greater than 3 m.

Testing the relationship between domestication and developmental instability in rainbow trout,Oncorhynchus mykiss(Teleostei, Salmonidae)

Fish domestication is an evolutionary process arising in captivity through genetic and developmental mechanisms, producing organisms performing more poorly than wild conspecifics in the natural environment. Culture conditions could be suboptimal for fish at particular life cycle stages, presenting environmental disturbances leading to developmental instability. The limited size of captive lots, moreover, can result in the loss of genetic variation, and the resulting homozygosity (as well as hybridization and mutation) could have strong harmful effects on developmental stability. Rainbow trout are the most widely-cultured species in Europe and North America, having been in culture for more than a century. Prolonged artificial selection for desired traits and incidental effects of domestication has led to the development of a ‘farmed type’. Fluctuating asymmetry, variations in meristic counts, and skeletal anomalies were examined in several rainbow trout captive and wild clonal lines as indicators of developmental instability. Differences in developmental stability were identified among lines and correlated with different degrees of exposure to captivity. Some relationship between meristic counts and domestication level was found in the present study, with the number of vertebrae and of dorsal pterygiophores and rays being the strongest predictors of the domestication level. However, the occurrence of skeletal anomalies and fluctuating asymmetry were apparently not related to the level of exposure to captivity. The findings of the present study will facilitate the selection of clonal lines with divergent phenotypes for subsequent quantitative trait loci analyses aimed at identifying genome regions linked with morpho-anatomical and physiological adaptive responses to captivity.

Osteology of the prowfish,Zaprora silenus(Cottiformes: Zoarcoidei: Zaproridae)

The prowfish, Zaprora silenus, is the sole member of the family Zaproridae. It is a large, relatively elongate species with a robust head and body, and it feeds primarily on jellyfishes. Although the larvae and juveniles are pelagic, the adults are demersal, and the species is widely distributed from Southern California around the Pacific Rim to Hokkaido, Japan. The stichaeid affinities of this species have long been recognized, and the family is currently placed, along with the Stichaeidae, in the Zoarcoidei. Previous anatomical studies of Zaprora have been based on relatively few specimens from a limited geographic range and have not included cleared and stained (c&s) specimens. Here, we provide a complete description of the osteology of the prowfish, based on a large series of specimens representing a broad ontogenetic range, including a series of c&s specimens. Our results contradict the findings of previous authors in the structure of the pharyngeal teeth, presence of the pelvic girdle, and the placement of the first dorsal pterygiophore. However, we concur with the findings of previous morphological and molecular phylogenetic studies, which indicate that the prowfish is probably most closely related to at least some members of the Stichaeidae.

Three new species of Bryconamericus (Characiformes, Characidae), with keys for species from Ecuador and a discussion on the validity of the genus Knodus

Three new species of characid fishes of the genus Bryconamericus are described from the Pacific coast and Amazon Basin in Ecuador, based on pigmentation and morphometric, meristic and osteological characters. B. bucayensis (n = 48) is distinguished by the number of scales between the lateral line and the pelvic–fin insertions (7–8 vs. 2–7, except B. terrabensis with 7–8 and B. arilepis with 9–10), the number of branched anal–fin rays (33–38 vs. 31 or fewer), the number of anterior anal–fin rays covered by a row of scales at their bases (28–31 vs. 4–26), and its wide anterior maxillary tooth being at least twice the width of the posterior tooth, both of which are pentacuspid (vs. maxillary teeth of same size). B. zamorensis (n = 126) is distinguished from congeners by having five teeth on the maxilla (vs. 1 or 2 teeth on maxilla), except B. rubropictus and B. thomasi, from which it differs in a reticulated pattern over the lateral stripe, generated by the concentration of melanophores, the scale margins, all along the sides of the body, the high number of branched anal–fin rays and vertebras, and the low branched dorsal–fin rays. The dorsal expansion of the rhinosphenoid forms a bony wall between olfactory nerves (vs. dorsal expansion of rhinosphenoid between olfactory nerves absent). Lateral process of palatine surpasses anterolateral margin of ectopterygoid (vs. palatine without lateral processes that laterally surpass the ectopterygoid), and the distal tip of sphenotic spine is laterally wide and undulated (vs. narrow). B. oroensis n. sp. (n = 124) is distinguished by having a dark lateral stripe overlaid with a peduncular spot and a reticulated pattern on the sides of the body (vs. peduncular spot and other body pigments not superimposed over a dark lateral stripe). It has three simple dorsal–fin rays, the first only visible in cleared and stained material and articulated, along with the second simple ray, with the first dorsal pterygiophores. The third simple ray is longer, and articulated with second dorsal pterygiophores (vs. only two simple dorsal–fin rays, both articulated with first dorsal pterygiophores). The anterior frontal is separated and so the fontanel front parietal is continued on the mesethmoids (vs. anterior tips of frontals united, and not separated by mesethmoids). Keys for identification of the species of Bryconamericus known to occur in Ecuador are included and the validity of the genus Knodus (vide Knodus carlosi) is discussed for cis Andean species.

A new species of Trichonotus (Perciformes: Trichonotidae) from Somalia and redescription of Trichonotus cyclograptus (Alcock, 1890) with designation of a lectotype

A new sand diver Trichonotus somaliensis n. sp. (Trichonotidae) is described on the basis of 13 specimens collected offthe coast of Somalia at a depth of 38−78m. The new species is most similar to T. arabicus and T. cyclograptus in lackingelongated anterior dorsal-fin spines and having dark markings on the lateral body surface in males. However, the new spe-cies differs from the others in having the following characters: lateral-line scales 54−57; gill rakers on first arch5−6+18−24; 12–14 blotches on upper half of body in both sexes; first dorsal-fin soft ray length in males 19–28% of stan-dard length; and no free dorsal pterygiophores. Trichonotus cyclograptus, a poorly known species, is redescribed on the basis of the newly-designated lectotype and paralectotypes.

A New Species of the Genus Eulophias (Zoarcoidei: Stichaeidae) from Korea

A new species, Eulophias koreanus, belonging to the family Stichaeidae, suborder Zoarcoidei, is described on the basisof five specimens (70.7–160.7 mm in standard length) collected from the southern sea of Korea. The new species differsfrom the only two known congeneric species, Eulophias tanneri and Eulophias owashii, which are endemic to Japan. Eu-lophias koreanus is readily distinguished from E. tanneri by the numbers of anal-fin rays (102–103 vs. 75 in E. tanneri)and caudal-fin rays (9–10 vs. 7). Eulophias koreanus is more similar to E. owashii than to E. tanneri, but differs from theformer in the number of vertebrae (141–143 vs. 133 in E. owashii) and pectoral-fin length (36.1–39.5% of HL vs. 27.8%).Regarding the caudal skeletons in E. koreanus, the last dorsal pterygiophore is inserted between the last 1st and 2nd or the2nd and 3rd neural spines, and a small spine is absent on the ventral portion of the parhypural, whereas in E. owashii, thelast dorsal pterygiophore is inserted between the last 3rd and 4th neural spines, and a small spine is present on the ventralportion of the parhypural. Analyses of 500-bp sequences of mitochondrial DNA cytochrome oxidase subunit I providestrong evidence that the five new specimens belong to the same species, even though they show some variation in head shape.

한국산 점농어(Lateolabrax maculatus) 자치어의 골격발달과 비늘형성

Early osteological development of the skull, vertebral column, and fins, and squamation in the spotted sea bass, Lateolabrax maculates, were studied under extensive larval rearing conditions. The first ossification during cephalic skeleton development began with the premaxillary, dentary, and parasphenoid at 6.4 mm Total length (Notochord length 6.1 mm) and was completed by 25.2 mm TL (Standard length 20.3 mm). Ossification of the cartilaginous caudal complex started simultaneously in the urostyle and two preural centra at 12.2 mm TL (10.4 mm) and it was completely ossified by 32.0 mm TL (26.4 mm). The principal caudal fin rays, with a count of 9/8, began to ossify at 11.6 mm TL (10.2 mm) and the procurrent caudal fin rays, with counts of 4 (upper) and 3 (lower), started to ossify by 12.6 mm TL (10.9 mm). Ossification of these parts was completed by 21.4 mm TL (17.5 mm). Ossification of the vertebral column was first observed in the first to fourth centra at 8.3 mm TL (7.5 mm) and was fully completed by 21.7-35.0 mm TL (17.8-29.3 mm). The pectoral girdle started to ossify by 5.6 mm TL (5.4 mm) and was completed by 26.8 mm TL (21.8 mm). Eight pectoral fin rays were ossified at 11.6 mm TL (10.2 mm) and 16-18 rays were fully ossified by 13.8 mm TL (12.0 mm). Also, the dorsal, anal, and pelvic fin rays started to ossify at 12.2 mm TL (10.4 mm) and were completed by 12.8 mm TL (11.2 mm), 23.8 mm TL (19.4 mm), and 13.8 mm TL (12.0 mm), respectively. Ossification of the anal and dorsal pterygiophores initially occurred by 12.6 mm TL (10.9 mm) and 14.3 mm TL (12.2 mm), and was completed by 21.4 mm TL (17.5 mm) and 19.3 mm TL (15.9 mm), respectively. Squamation started at three centers of differentiation: the middle region of the trunk, the anterior of the caudal peduncle, and on the caudal peduncle at 23.8 mm TL (19.4 mm). The body was covered with scales, except the snout, at 57.2-60.2 mm TL (SL 47.1-49.2 mm).

Molecular phylogeny of Aphyocharacinae (Characiformes, Characidae) with morphological diagnoses for the subfamily and recognized genera

The subfamily Aphyocharacinae was recently redefined to comprise eight genera: Aphyocharax, Prionobrama, Paragoniates, Phenagoniates, Leptagoniates, Xenagoniates, Rachoviscus and Inpaichthys. This new composition, however, is partially incongruent with published results of molecular studies especially concerning the positions of Rachoviscus and Inpaichthys. Our goal was to investigate the monophyly of Aphyocharacinae and its interrelationships using three distinct phylogenetic methodologies: Maximum-likelihood and Bayesian analyses of molecular data, and also Parsimony analysis of a concatenated molecular and morphological dataset. All tree topologies recovered herein suggest that Rachoviscus, Inpaichthys and Leptagoniates pi do not belong to the Aphyocharacinae. The remaining aphyocharacin taxa analyzed do form a monophyletic group, which is itself composed of two subgroups being one comprised of Paragoniates, Phenagoniates, Leptagoniates and Xenagoniates, and the other comprised of Aphyocharax and Prionobrama. Internal relationships among these genera are statistically well supported and morphological synapomorphies are presented at the generic level. All tree topologies also indicate that Aphyocharacidium is closely related to Aphyocharacinae suggesting that it should be included in this subfamily. As recognized in the present study, the Aphyocharacinae is diagnosed by a single morphological synapomorphy: two dorsal-fin rays articulating with the first dorsal pterygiophore.

Long‐Term PIT and T‐Bar Anchor Tag Retention Rates in Adult Muskellunge

AbstractMark–recapture studies require knowledge of tag retention rates specific to the tag types, fish species and size, and study duration. We determined the probability of tag loss for passive integrated transponder (PIT) tags implanted into dorsal musculature, T‐bar anchor tags attached to dorsal pterygiophores, and both tags in relation to years posttagging for double‐marked adult muskellunge Esox masquinongy over a 10‐year period. We also used PIT tags as a benchmark to assess the interactive effects of fish length at tagging, sex, and years posttagging on T‐bar anchor tag loss rates. Only five instances of PIT tag loss were identified; the calculated probability of a fish's losing its PIT tag was consistently less than 1.0% for up to 10 years posttagging. The probability of T‐bar anchor tag loss by muskellunge was related to both the number of years posttagging and the total length (TL) of the fish at tagging. The T‐bar anchor tag loss rate 1 year after tagging was 6.5%. Individuals of less than 750 mm TL at tagging had anchor tag loss rates less than 10% for up to 6 years after tagging. However, the proportion of fish losing T‐bar anchor tags steadily increased with increasing years posttagging (∼30% after 6 years) for larger muskellunge. Fish gender did not influence the probability of T‐bar anchor tag loss. Our results indicate that T‐bar anchor tags are best suited for short‐term applications (≤1 year) involving adult muskellunge. We recommend use of PIT tags for longer‐term tagging studies, particularly for muskellunge larger than 750 mm TL.Received November 19, 2010; accepted March 28, 2011

Effect of vitamin A on the skeletal morphogenesis of European sea bass, Dicentrarchus labrax (Linnaeus, 1758)

The purpose of this study was to examine the effects of vitamin A levels in the larval diet of Dicentrarchus labrax, (a) on the shape of juvenile skeleton and (b) on the development of pelvic fins. To exclude the side-effects of skeletal abnormalities on skeleton shape, morphometric analysis was performed on normal individuals only. Geometric morphometric analysis revealed a significant effect of larval nutrition on the shape of juvenile skeleton (Wilk's λ=0.0188, P<0.001), 55 days after the application of the different nutritional regimes. Between-groups shape differences mainly concerned the position of anterior dorsal pterygiophore, which was associated with a significant (P<0.05) increase of the number of dorsal lepidotrichia and hard spines at low levels of vitamin A (3–9 × 103 IU kg−1 dry food). At the lowest vitamin A levels (3 × 103 IU kg−1 dry food), the development of pelvic fins was abnormal, with severe bilateral (44±10%, mean±SD) or unilateral (22±9%) lack of the fin lepidotrichia, hard spines and their supporting elements. In the 82–94% of the unilaterally deformed individuals, deformation concerned the left pelvic fin. Concerning the shape of pelvic fins in the normally developed individuals, results demonstrated a significant effect of nutritional conditions on the size and position of all the elements of the pelvic fin area (basipterygium, lower metacleithrum, cleithrum, scapula) (Wilk's λ=0.3087, P<0.001). Our results demonstrate a significant nutritionally driven phenotypic plasticity in D. labrax, with dietary levels of vitamin A determining the skeleton shape and the left–right symmetry of pelvic fins.

A Morphological and Meristic Comparison of Larval and Juvenile Temperate Bass, Lateolabrax japonicus, from Various Sites in Western and Central Japan

Comparison of larval and juvenile specimens of the temperate bass, Lateolabrax japonicus, collected from 11 sites in western and central Japan, revealed that specimens from the Chikugo estuary located at the innermost Ariake Bay, differed markedly in morphology from other specimens. In the Chikugo specimens, melanophores were distributed more sparsely, the head was proportionately smaller and the numbers of dorsal pterygiophores and vertebrae were significantly lower. Larval and juvenile stages of the species were redescribed using specimens from the Shimanto estuary.

Gymnogeophagus eocenicus, n. sp. (Perciformes: Cichlidae), an Eocene cichlid from the Lumbrera Formation in Argentina

ABSTRACT A new cichlid referable to the extant genus Gymnogeophagus is described from the Eocene Lumbrera Formation of the Salta Group, northwestern Argentina. †Gymnogeophagus eocenicus, n. sp., presents the synapomorphies that support the genus: absence of supraneurals and a presence of a forward spine in the first dorsal pterygiophore. The existence of an early to middle Eocene–aged species presenting the synapomorphies and the appearance of a modern genus requires the acceptance of an extensive differentiation from the basal cichlid lineages. Extant Gymnogeophagus species are restricted to the La Plata drainage and a few coastal drainages of southern Brazil and Uruguay. The occurrence of an Eocene fossil in the geographical area corresponding to the present distribution of the genus suggests the patterns of distribution and endemism of the Neotropical fish fauna have a very old history in the continent.

A New Species of Deep-Water Tonguefish Genus Symphurus (Pleuronectiformes: Cynoglossidae) from Taiwan

Abstract A new symphurine tonguefish species, Symphurus megasomus, is described on the basis of 18 specimens collected in deep waters (471–640 m) off eastern Taiwan. This species is characterized by the combination of a predominant 1-2-3-2-2 pattern of interdigitation of dorsal pterygiophores and neural spines, 14 caudal-fin rays, 106–111 dorsal-fin rays, 91–96 anal-fin rays, 55–58 total vertebrae, 5 hypurals, deep body (27.2–30.8% SL), small (5.3–7.9% HL), round and separate eyes, bluish-black opercle and peritoneum on both sides of body (in both fresh and alcohol-preserved specimens), uniformly straw-colored to dark-brown ocular-side background pigmentation without freckles or mottled pigmentation, and uniformly white to light yellow blind side. Among congeners, S. megasomus is most similar to S. undatus, which has the same ID pattern and number of caudal-fin rays, but differs markedly from that species in having more dorsal- and anal-fin rays and in its ocular-side coloration (uniformly straw-colored t...