Vertebral Counts Research Articles

Phylogeny and Taxonomic Revision of the Endemic Malagasy Genus Ptychochromis (Teleostei: Cichlidae), with the Description of Five New Species and a Diagnosis for Katria, New Genus

The Malagasy cichlid genus Ptychochromis is revised and five new species are described, one of which is presumed to be extinct. The three valid nominal species, P. oligacanthus, P. grandidieri, and P. inornatus, are redescribed with diagnoses provided for each. A phylogeny of ptychochromin cichlids, derived from the simultaneous analysis of morphological features and nucleotide characters from a combination of mitochondrial and nuclear genes is presented. Ptychochromis is diagnosed by a suite of derived features of the pharynx, infraorbital series, and palatine morphology. In addition, the sister taxon to Ptychochromis, Ptychochromoides katria, is removed from Ptychochromoides and placed in its own genus, Katria, which is described herein as new. Katria is diagnosed by a unique pigmentation pattern, the absence of paired anterior gas bladder chambers that approach the neurocranium, an elevated vertebral count, and a slender caudal peduncle. An unnamed clade comprising Ptychochromis and Katria is diagnosed by a suite of derived features of the pharynx, sensory canal system, supraneural patterning, and palatine morphology.

A complete trematosaurid amphibian from the Middle Triassic of Germany

ABSTRACT Recent finds of small temnospondyls from the Lower Keuper (Ladinian, Middle Triassic) of southern Germany are referred to a new trematosaurid genus and species, Trematolestes hagdorni. It is the first trematosaurid represented by a nearly complete skeleton. Trematolestes is characterized by an unpaired frontal and a minute lacrimal at the orbital rim wedged in between an extensive prefrontal and a wide maxilla. Further characteristic are keeled, laterally compressed palatal tusks, a strong palatine and ectopterygoid dentition, and minute maxillary and posterior dentary teeth. In the visceral skeleton, ceratobranchial parts of the hyobranchial skeleton and an unpaired basibranchial element are ossified. The ribs bear pronounced spine-like uncinate processes throughout the trunk and anterior tail skeleton. The forelimb is minute, with a strongly abbreviated humerus not exceeding the length of the lower arm, rudimentary radius and ulna, and a small, probably four-fingered hand skeleton. Unlike the situation in capitosauroids, the trunk was deep with an elongated recurved ilium and a highly modified sacral rib. The trunk is composed of 22 vertebrae, while the caudal vertebral count is at least 24, but probably exceeded 30. Phylogenetic analysis suggests that Trematolestes is closely related to the Madagascan genus Tertremoides and together they are nested with the rostrum-bearing slender-headed lonchorhynchines.

Genetic evidence of cryptic speciation within hammerhead sharks (Genus Sphyrna)

Surveys of genetic variation within cosmopolitan marine species often uncover deep divergences, indicating historical separation and potentially cryptic speciation. Based on broad geographic (coastal eastern North America, Gulf of Mexico, western Africa, Australia, and Hawaii) and temporal sampling (1991–2003), mitochondrial (control region [CR] and cytochrome oxidase I [COI]) and nuclear gene (lactate dehydrogenase A intron 6 [LDHA6]) variation among 76 individuals was used to test for cryptic speciation in the scalloped hammerhead, Sphyrna lewini (Griffith and Smith). CR and COI gene trees confirmed previous evidence of divergence between Atlantic and Indo-Pacific scalloped hammerhead populations; populations were reciprocally monophyletic. However, the between-basin divergence recorded in the mtDNA genome was not reflected in nuclear gene phylogenies; alleles for LDHA6 were shared between ocean basins, and Atlantic and Indo-Pacific populations were not reciprocally monophyletic. Unexpectedly, CR, COI, and LDHA6 gene trees recovered a deep phylogenetic partition within the Atlantic samples. For mtDNA haplotypes, which segregated by basin, average genetic distances were higher among Atlantic haplotypes (CR: D HKY=0.036, COI: D GTR=0.016) than among Indo-Pacific haplotypes (CR: D HKY=0.010, COI: D GTR=0.006) and approximated divergences between basins for CR (D HKY=0.036 within Atlantic; D HKY=0.042 between basins). Vertebral counts for eight specimens representing divergent lineages from the western north Atlantic were consistent with the genetic data. Coexistence of discrete lineages in the Atlantic, complete disequilibrium between nuclear and mitochondrial alleles within lineages and concordant partitions in genetic and morphological characters indicates reproductive isolation and thus the occurrence of a cryptic species of scalloped hammerhead in the western north Atlantic. Effective management of large coastal shark species should incorporate this important discovery and the inference from sampling that the cryptic scalloped hammerhead is less abundant than S. lewini, making it potentially more susceptible to fishery pressure.

Review of the Dinematichthyini (Teleostei: Bythitidae) of the Indo-west Pacific. Part I. Diancistrus and Two New Genera with 26 New Species

An ongoing revision of the dinematichthyine fishes (Ophidiiformes, Bythitidae, Brosmophycinae) of the Indo-West Pacific based on ca. 5000 specimens will be published in parts. Part I includes 765 identified specimens in the genera Brotulinella (new genus with one new species), Diancistrus Ogilby, 1899 (with four described and 23 new species) and Paradiancistrus (new genus with two new species). The main distinguishing character in this group of presumably related genera is the male pseudoclasper pattern. Brotulinella is further characterized by the slender form and the generally higher number of precaudal vertebrae (12 versus 11 in the two other genera, except for one species with 12 in Diancistrus). Paradiancistrus is unique amongst Indo-West Pacific dinematichthyine genera in having only one instead of three lower preopercular pores. Brotulina Fowler, 1946, Calcarbrotula Fowler, 1946 and Parabrosmolus Machida, 1996, are regarded as junior synonyms of Diancistrus. The separating characters of the species are male pseudoclaspers, head squamation, head pores, otoliths, morphometric proportions, and finray and vertebral counts. Diancistrus, which has remained monotypic for more than 100 years, is here shown to be one of the most diverse genera of tropical reef fishes. The many unrecognised species have previously been confused with other genera such as Dinematichthys and Ogilbia. Pseudoclasper morphology is used to define three informal species groups in the genus Diancistrus.

Description of a new species of weasel shark, Hemigaleus australiensis n. sp. (Carcharhiniformes: Hemigaleidae) from Australian waters

A new species of weasel shark from the genus Hemigaleus Bleeker, 1852 (Carcharhiniformes: Hemigaleidae) is described from northern Australia. Hemigaleus australiensis n. sp. is known from the insular and continental shelves of northern Australia from inshore bays to depths of 170 m. The new species differs from the only other member of this genus, Hemigaleus microstoma, in having substantially lower vertebral counts, much higher tooth counts in lower jaw, and a black-tipped second dorsal fin. Hemigaleus australiensis and H. microstoma are also readily separated by differences in morphometrics and sizes at birth and maturity.

Additions to the ichthyofauna of the Tristan da Cunha Group, South Atlantic Ocean

Specimens of two, possibly three, rare species of fishes were collected at the Tristan da Cunha Group toward the end of a 2004 South Atlantic cruise (ICEFISH). The dragonet Synchiropus valdiviae (Trunov, 1981), was previously known from only two adult males taken on Walvis Ridge. We collected two adult females and three juveniles, which are described here. The pearlfish Echiodon atopus Anderson, 2005, was recently described from a specimen collected north of Inaccessible Island. It differs from congeners in its high precaudal vertebral count, equivalent dorsal and anal rays anterior to vertebra 31 and other features of the axial skeleton and fins. Lastly, an unusual specimen of the rockfish genus Sebastes taken in a commercial lobster pot represents either a previously unreported variant of S. capensis or an undescribed species. It differs from the typical South Atlantic S. capensis in its coloration and lack of supraocular spines.

Bayesian analysis of allozyme markers indicates a single genetic population of kingklip Genypterus capensis off South Africa

Kingklip Genypterus capensis inhabit deep continental shelf and slope waters off southern Africa and are now largely harvested as a bycatch in trawl and longline fisheries for Cape hakes Merluccius spp. Regional differences in growth, vertebral count and otolith morphology indicate that kingklip may consist of three stocks. In this study, allozyme markers are used to test whether the two southern stocks, the putative Cape and South Coast stocks, are genetically distinguishable. Standard electrophoretic methods detected Mendelian polymorphisms at six (23%) of 26 enzyme-encoding loci in five samples extending from about 29°S on the West Coast to about 25°E on the South Coast. No deviations from Hardy-Weinberg proportions were observed in the samples or in the pooled sample. Gene diversities (heterozygosity) ranged from HS = 0.039 to 0.042 among samples, and averaged 0.041. Genetic differentiation among localities was remarkably small, FST = 0.003, and did not differ significantly from zero. A Bayesian analysis of population structure, based on detecting departures from Hardy-Weinberg proportions and gametic phase equilibria between loci, indicated with a high likelihood that the five samples were drawn from a single genetic population. In combination, these results are consistent with the occurrence of a single population off South Africa. However, the most conservative management strategy is to set harvest quotas individually on the Cape and South Coast stocks.

Age and size at sexual maturity for the winter skate, Leucoraja ocellata, in the western Gulf of Maine based on morphological, histological and steroid hormone analyses

We determined age and size at sexual maturity in male and female winter skates, Leucoraja ocellata, from the western Gulf of Maine. Age estimated from vertebral band counts resulted in an Index of Average Percent Error (IAPE) of 5.6%, suggesting that this method represents an accurate approach to the age assessment of L. ocellata. Size at sexual maturity was assessed by evaluating three endpoints: steroid hormone concentrations, and morphological and histological criteria. Our results suggest that 50% maturity in males occurs at a total length of 730 mm and at 11 years of age. For females, our results suggest that 50% maturity occurs at a total length of 760 mm and between 11 and 12 years of age. Collectively, our study suggests that analyzing a combination of reproductive parameters offers an accurate estimation of sexual maturity in the winter skate. Moreover, our results indicate that L. ocellata is a late-maturing and long-lived species, characteristics which make it highly susceptible to over-exploitation by commercial fisheries.

Description and relationships of a new ichthyodectiform fish from the Tlayúa Formation (Early Cretaceous: Albian), Puebla, Mexico

ABSTRACT A new species is described and proposed as a new genus and family belonging to the Order Ichthyodectiformes. The specimens referred to this taxon were collected in limestones of the Middle Member of the Tlayúa Formation of Albian age, near Tepexi de Rodríguez, Puebla, central Mexico. This new species shows a unique combination of primitive and derived characters. Its head and body proportions resemble those of other Cretaceous ichthyodectiforms, but its parietals are unfused and the caudal fin has three epurals and five uroneurals; it is also characterized by an unusually high total vertebral count, which comprises 78–80 centra, and areas of crowded teeth in the dentary and maxilla.

A review of the systematics of the sleeper shark genus Somniosus with redescriptions of Somniosus (Somniosus) antarcticus and Somniosus (Rhinoscymnus) longus (Squaliformes: Somniosidae)

Past treatments of the sleeper shark genus Somniosus generally recognize three species: S. microcephalus, S. pacificus, and S. rostratus. Based on morphometrics and meristics, we conclude that this genus includes two subgenera (Somniosus and Rhinoscymnus) and five species. Subgenus Somniosus differs from Rhinoscymnus by being much larger when adult and in having more numerous tooth rows in the lower jaw, hooklike rather than leaf-shaped dermal denticles, more numerous spiral valve and vertebral counts, and a poorly calcified vertebral column. Subgenus Somniosus includes S. (Somniosus) microcephalus and S. (S.) pacificus of the Northern Hemisphere and S. (S.) antarcticus of the Southern Hemisphere. Although Somniosus antarcticus has been synonymized with S. microcephalus and identified as S. pacificus in past literature, it differs from S. microcephalus in having a shorter interdorsal space, a more posterior first dorsal fin, lower dorsal fins, more numerous tooth rows in the lower jaw, more numerous spiral valve counts, and fewer precaudal vertebrae. Somniosus antarcticus also differs from S. pacificus by having a shorter prebranchial length, lower dorsal fins, more numerous spiral valve counts, and slightly more precaudal vertebrae. Subgenus Rhinoscymnus includes S. (Rhinoscymnus) rostratus from the eastern North Atlantic and Mediterranean Sea (senior synonym of S. bauchotae) and S. (R.) longus from the western Pacific Ocean. Somniosus longus has been synonymized with S. rostratus, but differs in having a relatively longer second dorsal fin, a slightly larger eye, more lower tooth rows, and slightly higher spiral valve counts. Both Somniosus (Somniosus) antarcticus and S. (Rhinoscymnus) longus from the Pacific Ocean were redescribed. A key to the species and the geographical distribution of all species are provided.

The northern river shark Glyphis sp. C (Carcharhinidae) discovered in Western Australia

Seven specimens of Glyphis sp. C were collected from macrotidal mangrove systems near the town of Derby in the Kimberley region of Western Australia, which represents the first capture in this state. The five males and two females ranged in length from 906 to 1418 mm TL, weighed between 5150 and 18640 g and had a vertebral count range outside that previously reported for the species, i.e. 140 151 cf 147 148. The unusually high incidence of fused vertebrae and spinal deformation may suggest a small gene pool in this population. Previous occurrences of this species were restricted to rivers in the Northern Territory (Australia) and Papua New Guinea. The presence of a small eye (mean diameter 0.87% of total length), large dorsal and pectoral fins, and well defined sensory ampullae may be reflective of living in an environment subjected to extreme turbidity and flows.

Threatened fishes of the world: Galaxias auratus Johnston, 1883 (Galaxiidae)

Common name: Golden galaxias. Conservation status: Rare – (Tasmanian Threatened Species Protection Act 1995); Endangered – ASFB (2003). Identification: D 7–10, A 11–12, P 14–18, vertebral count 53–56 (McDowall & Frankenberg 1981). Small scaleless salmoniform fish, maximum size: 240 mm TFL, 130 g (Hardie 2003). Colouration: golden to olive-green on dorsal surface and sides, silvery-grey on ventral surface. Back and sides are covered with round to oval black spots (McDowall & Frankenberg 1981). Drawing by Carol Kroger in Fulton (1990).

THE DEVELOPMENTAL BASES OF LIMB REDUCTION AND BODY ELONGATION IN SQUAMATES

Employing an integrative approach to investigate the evolution of morphology can yield novel perspectives not attainable from a single field of study. Studies of limb loss and body elongation in squamates (snakes and lizards) present a good example in which integrating studies of systematics and ecology with genetics and development can provide considerable new insight. In this comment we address several misunderstandings of the developmental genetic literature presented in a paper by Wiens and Slingluff (2001) to counter their criticism of previous work in these disciplines and to clarify the apparently contradictory data from different fields of study. Specifically, we comment on (1) the developmental mechanisms underlying axial regionalization, body elongation, and limb loss; (2) the utility of presacral vertebral counts versus more specific partitioning of the primary body axis; (3) the independent, modular nature of limbs and limb girdles and their utility in diagnosing genetic changes in development; and (4) the causal bases of hind limb reduction in ophidian and nonophidian squamates.

Hemitriakis complicofasciata, a new whitefin topeshark (Carcharhiniformes: Triakidae) from Japan

Hemitriakis complicofasciata sp. nov. is described from 18 specimens from the waters of the Ryukyu Islands, southern Japan. This new species is distinguishable from other congeners by the following characters: higher vertebral counts (46–52 monospondylous vertebrae and 124–131 precaudal total vertebrae), presence of a developed posterior nasal flap, first dorsal fin origin anterior to free rear tips of pectoral fin, shorter snout length (snout tip to oral length less than 1.8 times internarial width), absence of an accessory cartilage at symphysial part of upper jaw, and dark complicated lines and rings on embryos and juveniles.

Gymnothorax hansi, a new species of moray eel (Teleostei: Anguilliformes: Muraenidae) from the Comoro Islands, Western Indian Ocean

Gymnothorax hansi, a new species of moray eel, is described from three specimens caught in ~ 146 m at Grand Comoro (Ngazidja) Island in the Comoros Islands. The length of the head plus the body is distinctly longer than tail; the dorsal fin origin is at a vertical midway between the gill opening and the rear edge of the eye. The head length is 11 to 12% total length. The colour is chestnut brown dorsally on the head, body and most of the tail; the dorsal and anal fins are brown anteriorly, blackish posteriorly with a bright white margin from dorsal fin origin round the tail tip to the anal fin origin; anterior nostril tube, posterior nostril mound and iris are yellow; head and ventrolateral part of body of 101 cm adult male golden brown, with several, irregular, distinct, dusky or black spots scattered over most of the body, tail and dorsal fin; head of 101 cm adult female brown dorsally, paler below; female with a few faint dusky spots on body and tail; both sexes with pores on jaws set in white spots. Teeth small, sharp, caniniform, slightly curved, uniserial on maxillae and dentaries; longest intermaxillary tooth equals 64% eye diameter; vomer with 3 minute teeth. The vertebral counts are higher than in most morays: 4 predorsal, 82 84 preanal and 183 185 total.

Injury of American Eels Captured by Electrofishing and Trap‐Netting

AbstractWe compared the incidence of internal injuries in adult American eels Anguilla rostrata captured by trap‐netting (N = 20) and by 30‐Hz, pulsed‐DC electrofishing (N = 18) in the St. Lawrence River, New York. On average, the lengths and weights of fish caught by the two methods were similar. Radiographic imaging revealed that spinal damage occurred in 60% of the electroshocked American eels but only 15% of the trap‐netted American eels. Bilateral filleting showed hemorrhages in 30% of the electroshocked fish but none of the trap‐netted fish. Electrofishing caused significantly higher incidences of both spinal damage and hemorrhage than did trap‐netting. Most electroshocked American eels had multiple spinal injuries; hemorrhages occurred only in fish with multiple sites of vertebral damage. We recommend that workers avoid the use of 30‐Hz, pulsed DC to capture American eels that are intended for release; a lower frequency, such as 15 Hz, may significantly reduce injury but may also result in unacceptably low capture rates. We hypothesize that electroshocked American eels are at high risk for injury because of their large size (>90 cm) and high vertebral count (>100).

Osteological variation and taxonomic affinities of bottlenose dolphins, Tursiops spp., from South Australia

Skulls and skeletons of 84 cranially mature bottlenose dolphins collected from South Australia were studied to distinguish morphological groups. The dataset comprised 38 skull measurements, 5 tooth counts/measurements, 6 coded skull features and 2 vertebral counts. There was no significant difference between sexes. Agglomerative, heirarchical cluster analyses performed on all variables and a dataset refined by eliminating those with high partial correlations produced two clear groups of skulls but with some differences in group membership between the statistical treatments. Size was an important factor in distinguishing groups, especially when categorical variables were excluded. Groups produced by cluster analysis of all variables were aligned with Tursiops truncatus and T. aduncus. In general, Tursiops truncatus was distinguished by a wide band (3-9 mm) of cancellous bone on the premaxillae, a distinct supraoccipital crest, raised naso-frontal complex, the almost complete lack of bone resorption on the pterygoid bones, a relatively wider rostrum, generally larger skull size (condylobasal length >465 mm versus <476 mm, except two skulls of 445 and 448 mm), and more than 60 vertebrae. This species was collected from open ocean coasts and sometimes stranded in groups. Tursiops aduncus generally had a narrow or no band of cancellous bone (0-5 mm), an indistinct or no supraoccipital crest, a naso-frontal complex that was not markedly raised, moderate to extensive bone resorption on the pterygoids, relatively narrow rostrum, fewer than 63 vertebrae and was collected mainly from the large gulfs. There was no significant difference between tooth diameter of T. aduncus and T. truncatus from South Australia.

THE DEVELOPMENTAL BASES OF LIMB REDUCTION AND BODY ELONGATION IN SQUAMATES

Employing an integrative approach to investigate the evolution of morphology can yield novel perspectives not attainable from a single field of study. Studies of limb loss and body elongation in squamates (snakes and lizards) present a good example in which integrating studies of systematics and ecology with genetics and development can provide considerable new insight. In this comment we address several misunderstandings of the developmental genetic literature presented in a paper by Wiens and Slingluff (2001) to counter their criticism of previous work in these disciplines and to clarify the apparently contradictory data from different fields of study. Specifically, we comment on (1) the developmental mechanisms underlying axial regionalization, body elongation, and limb loss; (2) the utility of presacral vertebral counts versus more specific partitioning of the primary body axis; (3) the independent, modular nature of limbs and limb girdles and their utility in diagnosing genetic changes in development; and (4) the causal bases of hind limb reduction in ophidian and nonophidian squamates.

Analysis of Three Cisco Forms (Coregonus, Salmonidae) from Lake Saganaga and Adjacent Lakes Near the Minnesota/Ontario Border

Based on examination of 655 ciscoes from Lake Saganaga, a Minnesota/Ontario border lake, three forms, about 90% separable on gill raker counts, are present. Form L, with the lowest gill raker counts (26–40, mean = 31.9, n = 96) is tentatively identified as Coregonus zenithicus. Form M, with intermediate gill raker counts (36–50, mean = 43.1, n = 92) was the only cisco anticipated to occur in lakes of the region and is assumed to represent Coregonus artedi. Form H, with 45–70 gill rakers, mean = 56.1, n = 467, is the most common cisco in the lake. We argue that the appropriate name for this form is Coregonus nipigon. Additional differences among the three forms include lateral-line scale and vertebral counts, gill raker length, body shape, fin pigmentation, size at sexual maturity, and maximum size. Seagull Lake, affluent to Lake Saganaga, contained only C. artedi (n = 108). Gunflint and Magnetic Lakes, also affluents to Lake Saganaga, contained C. artedi (n = 19) and C. zenithicus (n = 29). Lake Saganagons, immediately downstream of Lake Saganaga, based on only eight available specimens, appears to contain C. nipigon (7) and C. artedi (1).

Tooth row counts, vicariance, and the distribution of the sand tiger shark Carcharias taurus

Geographic variation in tooth row counts among sand tiger sharks Carcharias taurus (Chondrichthyes), from the SW Atlantic, NW Atlantic and the East China Sea is analyzed in this paper. We found significant differences between sand tigers from the SW Atlantic (Southern Hemisphere population) and each of the other two (Northern Hemisphere) regions in the number of upper lateral tooth rows, and between individuals from the SW Atlantic and the East China Sea in the total number of upper tooth rows. Sand tiger sharks from the two Northern Hemisphere populations did not differ in any of the studied variables. Our results agree with comparisons of vertebral counts between sand tiger sharks from Southern and Northern Hemispheres. Both lines of evidence suggest that Southern and Northern Hemisphere populations of C. taurus were isolated to a larger extent than populations of the Northern Hemisphere. The fossil record of the genus Carcharias begins in the Early Cretaceous and C. taurus is certainly known since the Late Miocene. During the Miocene, the Tethys Sea separating northern and southern land masses was still present and it provided a continuous temperate shallow sea that could allow dispersal of sand tiger sharks along Northern Hemisphere seas. Independent observations on the distribution and evolutionary history of the genera Myripristis, Neoniphon, Sargocentron and Aphanius, and genetic studies on the temperate shark genus Mustelus that indicate a close relationship between the Indo‐Pacific M. manazo and the Mediterranean M. asterias suggest that this hypothesis is plausible and deserves to be tested.