Ray Counts Research Articles

Two new species and two new records of aploactinid fishes (Pisces: Scorpaeniformes) from Australia

Two new species of aploactinids are described from coastal waters of subtropical eastern Australia. Pseudopataecus taenianotus, new genus and species, is described from seven specimens trawled inside the Capricorn-Bunker Group, Queensland. It is readily distinguished from other aploactinids by the markedly compressed head and body, large number of dorsal and anal-fin ray elements, frontal bone with laterally-bowed ridges forming a shallow fleshy depression, and distinctly anterior insertion of the first dorsal spine. Cocotropus microps, new species, is described from three specimens collected from inshore waters of southern Queensland and northern New South Wales. It has the lowest dorsal- and anal-fin ray counts of the genus, dorsal fin forming three elevated sections, and coloration including at least several small pale irregular spots or larger blotches. Two aploactinid species are recorded in Australian waters for the first time. Acanthosphex leurynnis Jordan & Seale, 1905, previously known from Hong Kong, Gulf of Thailand, southeast India, Indonesia and eastern Papua New Guinea, is reported from the Cumberland Group in tropical eastern Australia, Arafura Sea, Northern Territory, and near Perth, Western Australia. Xenaploactis cautes Poss & Eschmeyer, 1980, previously known only from the Andaman Sea and Gulf of Thailand, is reported from off Dampier, northwestern Australia and Gulf of Carpentaria, Queensland.

Larval development of Achoerodus viridis (Pisces: Labridae), the Australian eastern blue groper

Larvae of the southeastern Australian endemic hypsigenyin labrid Achoerodus viridis are described and illustrated from 30 specimens (3.0–9.6 mm) captured in plankton nets and larval fish beach seines. Development is typical for labrids. Larvae of A. viridis can be distinguished from those of other labrids because they possess distinctive pigment, 28 myomeres, and fin ray counts of D XI,11, A III,11, and P1 16–18. Larvae of closely related hypsigenyin labrid genera are poorly known but are similar in morphology and pigmentation. Adult A. viridis live on coastal rocky reefs. Larvae of 3.0–8.2 mm were captured over the continental shelf off central New South Wales in the Western Tasman Sea. Larvae of 6.6–7.7 mm were captured in a tidal channel leading to an estuarine lagoon, and the smallest larvae captured in seagrass beds in the lagoon were 7.2 and 8.5 mm.

Threatened Fishes of the World: Noturus placidus Taylor, 1969 (Ictaluridae)

Common names: Neosho madtom (T). Conservation status: Listed federally as threatened 22 May 1990 (USFWS 1991). Identification: One of 25 madtom species, distinguished from four madtoms in its range by two distinct crescent-shaped bands of pigment on caudal fin and lack of dark pigment extending to edge of adipose fin (Taylor 1969). Pectoral spines have poorly developed saw-like teeth on front margin. Fin ray counts: anal rays 13–16 (14.72); pelvic rays 8–12 (9.06), soft pelvic rays 7–9 (7.99); caudal rays 49–59 (54.32); vertebrae: 32–36 (33.62). Adults typically greater than 50 mm TL (Bulger & Edds 2001). Males in spawning condition exhibit swollen cephalic epaxial muscles and elongated genital papillae; both sexes exhibit reddened tooth patches during spawning season. Photograph by Janice L. Bryan. Distribution: Endemic to Neosho River basin in Kansas, Missouri, and Oklahoma (Taylor 1969). Species’ range historically extended south to Illinois River in Oklahoma; currently restricted by reservoirs to approximately two-thirds of original range (Moss 1981). Abundance: Large population fluctuations occur seasonally and annually (Moss 1981). In 1 year, Wilkinson et al. (1996) reported a mean summer density of occurrence in the Spring River of 11.3 fish versus 30.0 per 100 m in the autumn when generational overlap ocurrs. Higher mean autumn densities found in the Neosho River compared to the Spring River (Wildhaber et al. 2000a). Habitat and ecology: Occur over gravel bars and riffles in fourth to sixth order streams having moderate current, permanent flow, and unconsolidated gravel (Fuselier & Edds 1994; Bulger & Edds 2001). Nocturnal benthic insectivores gathering prey from gravel interstices (Moss 1981). In nature, young-of-the-year (YOY) 15–49 mm TL; mature individuals reach 33–82 mm TL by end of first year (Fuselier & Edds 1994; Bulger & Edds 2001). Suspected life span 1–2 years. Reproduction: Sexual maturity reached during first year (Bulger & Edds 2001). Spawning occurs mid-summer; YOY found July–August. Nests excavated beneath large rocks in unconsolidated gravel. Male parental care lasts 18–19 days (Bulger et al. 2002). Clutch size 60; mean chorion diameter 3.1 mm. Threats: Impoundments restrict migration, alter natural hydrograph, and with gravel mining, eliminate preferred habitat (USFWS 1991). Water quality and quantity impacted by municipalities, agriculture, zinc–lead mining, urbanization, and industrialization (Wildhaber et al. 2000a). Conservation actions: Federally listed as threatened in 1990; threatened status in Kansas and endangered in Missouri and Oklahoma. Recovery plan published in 1991 (USFWS 1991). Five-year moratorium on gravel mining in Neosho River instituted spring 1991. Annual population monitoring conducted since 1991 (Wildhaber et al. 2000b). Recent and ongoing research efforts focused on Neosho madtom ecology. Conservation recommendations: Continue to limit gravel mining, prohibit dam construction, and encourage removal of unused dams. Further research needed on life history. Remarks: Cooperation of government agencies and private landowners crucial to recovery.

A morphometric and meristic investigation of Lusitanian toadfish <i>Halobatrachus didactylus</i> (Bloch and Schneider, 1801): evidence of population fragmentation on Portuguese coast

SUMMARY: A total of 207 specimens of Lusitanian toadfish Halobatrachus didactylus from six different localities were analysed in terms of morphometric and meristic characters in order to investigate the hypothesis of population fragmentation on the Portuguese coast. This study confirmed the relative isolation between the Algarve populations and those from the western estuaries, which also showed a high degree of discrimination among them. Morphometric characteristics were much more adequate than meristic characters for a good separation of these populations. The most relevant morphometric characteristics for separation between H. didactylus populations were head width, interorbital width and pelvic fin length. These three variables were very useful for separation between western populations and seem to play an important role in species feeding activity. The caudal peduncle development is mainly related to the specimen’ swimming ability and was particularly relevant for discrimination between northern and southern populations and between estuarine and adjacent marine populations, apparently due to differences in hydrodynamic conditions. Meristic variation is mostly of a latitudinal nature (mainly nasal tentacles and pores on the lower jaw) but some differences between estuarine and marine populations (principally fin rays counts) related to water temperature were also observed.

Odontamblyopus rebecca, a new species of amblyopine goby from Vietnam with a key to known species of the genus (Gobiidae: Amblyopinae)

A new species of amblyopine goby, Odontamblyopus rebecca, is described on the basis of 37 specimens from Vietnam. It differs from other species of Odontamblyopus by the following combination of characters: caudal vertebrae typically 20; dorsal fin with 44-48 total elements; anal fin with 37-42 total elements; and pectoral-fin ray count 40-51. This species is figured and compared with other known species of Odontamblyopus.

Smoothing and Change Point Detection for Gamma Ray Count Data

Gamma ray detectors are used to measure the natural radioactivity of rocks. For a number of boreholes drilled at a site the gamma ray detector is lowered into each borehole and counts of gamma ray emissions at different depths are recorded as the instrument is gradually raised to ground level. The profile of gamma counts can be informative about the geology at each location. The raw count data are highly variable, and in this paper we describe the use of adaptive smoothing techniques and change point models in order to identify changes in the geology based on the gamma logs. We formulate all our models for the data in the framework of the class of generalized linear models, and describe computational methods for Bayesian inference and model selection for generalized linear models that improve on existing techniques. Application is made to gamma ray data from the Castelreagh Waste Management Centre which served as a hazardous waste disposal facility for the Sydney region between March 1974 and August 1998. Understanding the geological structure of this site is important for further modelling the transport of pollutants beneath the waste disposal area.

Calibration of the photometric method of heavy ion charge measurements in emulsion using a CCD camera

Abstract A previously developed method of heavy ion charge measurements in emulsion has been significantly improved. The charge measurements are based on analysis of photometric profiles of the particle tracks in emulsion. These profiles are obtained using a CCD camera mounted on an optical microscope. So far, the manual charge determination by delta ray counting had to be used for calibration of the photometric method. In this paper a complete procedure for calibration of the photometric method is shown, without resorting to the manual method.

Descriptive morphology of the eggs, larvae, and juveniles of two cyprinid fishes belonging to the Zacco temminckii species' group

Embryonic, larval, and juvenile development of two cyprinid species belonging to the Zacco temminckii species' group, Z. temminckii (Temminck and Schlegel) and Zacco sp. (type A), are described and compared with each other from laboratory-reared and wild specimens. The eggs of both species were closely similar except in diameter [1.92–2.20 mm in Z. temminckii vs. 1.60–1.75 mm in Z. sp. (type A)], being demersal, almost spherical in shape, transparent and unpigmented, with a pale yellow yolk, and no oil globule. Hatching occurred 40–53 h after fertilization in Z. temminckii and after 47–60 h in Z. sp. (type A). The newly hatched larvae of both species [4.9–5.3 mm in body length (BL) in Z. temminckii and 3.5–4.8 mm BL in Z. sp. (type A)] also resembled each other, having a large transparent pear-shaped yolk and lacking body pigmentation. Myomere counts of Z. temminckii and Z. sp. (type A) larvae and juveniles were 24–27 + 14–17 = 41–42 and 23–27 + 14–17 = 40–41, respectively. The yolk was completely absorbed at 8.3 mm BL in Z. temminckii and at 6.6 mm BL in Z. sp. (type A). Notochord flexion was initiated and completed at 7.8 mm BL and 8.2 mm BL in Z. temminckii and at 6.3 mm BL and 6.6 mm BL in Z. sp. (type A), respectively. Aggregate numbers of all fin rays were completed at 17 mm BL in Z. temminckii and 13 mm BL in Z. sp. (type A). Although the morphology of larvae and juveniles of both species was very similar, differences in body length of each developmental stage, the duration and process of disappearance of the adipose finfold, the anal fin ray counts, and pigmentation on the lateral body surface were clearly recognized.

Morphological differences among three color morphotypes of Sebastes inermis (Scorpaenidae)

Morphological differences among three color morphotypes occurring almost sympatrically (A, reddish type; B, blackish type; C, brownish type) of Sebastes inermis are clarified. Twenty-six morphometric characters and seven meristic characters were examined on about 20 specimens of each morphotype, 15 of the morphometric characters differing significantly. Principal component analysis (PCA) of the morphometric characters showed morphotype C to differ from the other two morphotypes. Canonical discriminant analysis (CDA) of the morphometric characters showed clear separation of each morphotype. Four meristic characters also differed significantly. Modes of pectoral fin ray counts of morphotypes A, B, and C were 15, 16, and 17, respectively, and the modes of anal fin ray counts of morphotypes B and C were 7 and 8, respectively. Many individuals of morphotype A had seven or eight anal fin rays. These differences suggested that the three morphotypes may be reproductively isolated from each other.

Postembryonic development of the tubenose goby Proterorhinus marmoratus Pallas (Gobiidae) in the St. Clair River/Lake system, Ontario

Postembryonic developmental stages (5-40 mm) of the tubenose goby Proterorhinus marmoratus (PALLAS) are described and illustrated. Fish were collected in vegetated shore habitat in the St. Clair River/Lake system, Ontario, during 1994-2000. At hatch, the tubenose goby is precocious and closely resembles juveniles. Distinguishing morphologic characters include a cottid-like body with broad head, dorsolateral eyes, tubular anterior nostrils, two dorsal fins, thoracic fused pelvic fins, and spatulate caudal fin. Modal values for pre- and postanal myomeres are 11 and 20, respectively. The first dorsal fin has 6 spines, and the second dorsal fin has 16 soft rays. Anal, pectoral, pelvic fin spine and ray counts are I-13, 15, and I-5, respectively. Black stripes on snout, occiput, and anterior membranes of the first dorsal fin are distinguishing pigmentary features.

Mastigopterus imperator Smith and Radcliffe, 1913, a senior synonym of M. praetor Smith and Radcliffe, 1913 (Ophidiidae, Ophidiiformes)

A rare deep-sea ophidiid genus Mastigopterus known to contain two species, M. imperator Smith and Radcliffe, 1913 and M. praetor Smith and Radcliffe, 1913, was reviewed on the basis of six specimens including the holotypes of both species. Dorsal and anal fin ray counts and the size of cephalic sensory pores previously thought to be diagnostic characteristics to discriminate the two species did not suggest the presence of two forms, the large (M. imperator) and the small species (M. praetor), in the genus. Apparently the genus is represented by a single species, M. imperator, known from off Madagascar, the East and South China Seas and Papua New Guinea.

Redescription of the gobiid fish genus Pseudotrypauchen (Gobiidae : Amblyopinae) and its significance in amblyopine phylogeny

The Indo–West Pacific gobiid genus Pseudotrypauchen is defined and redescribed. Pseudotrypauchen comprises one species,P. multiradiatus, known only from India, Malaysia, and Sumatra. A figure and description of this species are given. Pseudotrypauchen is unique within the Amblyopinae in having short, compressed, and gently rounded teeth in the outermost row on jaws, and in having the first two pterygiophores of the second dorsal fin separated by a neural spine. The latter character is unique within the subfamily. Owing to their shared possession of (1) free and silk-like pectoral-fin rays, and (2) a high pectoral-fin ray count, Odontamblyopus is a more likely candidate as sister group to Pseudotrypauchen than any other member of the Amblyopinae. Other relationships of Pseudotrypauchen are discussed.

A New Genus of Small Gobiid Fish (Teleostei, Gobiidae) from the Indo-west Pacific, with Description of Two New Species

A new genus, Tryssogobius, is created for two new species of Indo-west Pacific gobiids (T colini n. sp. and T. longipes n. sp.). The two species are distinguished by differences in fin rays counts, oculoscapular pores, body shape, and coloration. Both species are small, less than 30 mm SL, and occur in relatively deep coral reef habitats, where they hover above the substrate in a manner reminiscent of the microdesmid Nemateleotris.

Osteological development of the vertebral column and of the fins in Diplodus sargus (Teleostei: Perciformes: Sparidae)

The osteological development of vertebral column and fins in white sea bream, Diplodus sargus (Linnaeus, 1758) was studied. Vertebral ontogeny started at 5.7 mm total length (TL, post-fixation), with the formation of the first cartilaginous neural and haemal arches, and was completed by the full attainment of dorsal ribs (20.8 mm TL). The formation of vertebral centra occurred between 7.3 and 9.4 mm TL, but was fully completed only after the development of post- and pre-zygapophyses (26.0 mm TL). Pectoral supports were the first fin elements that started to develop (3.8 mm TL), followed by those of the caudal fin (5.2 mm TL), dorsal and anal fins (6.7 mm TL), and then by those of the pelvic fin (9.5 mm TL). The caudal fin of D. sargus was the first to develop fin rays and attain the full count of lepidotrichia (5.6–7.8 mm TL), but the last to attain the full count of dermatotrichia (7.9–16.0 mm TL). The next fins starting to present rays were the pectoral (6.5 mm TL) and the dorsal and anal fins (7.5 mm TL), while the pelvic fins were the last (11.5 mm TL). Following the caudal lepidotrichia (7.8 mm TL), the anal (10.5 mm TL), dorsal (12.0 mm TL), pectoral (11.4 mm TL) and pelvic fins (12.5 mm TL) were the next with fully completed ray counts. Finally, fin meristics were fully developed with the caudal dermatotrichia. The results are discussed in comparison with the fin and vertebral ontogeny of other teleosts.

Review of Polydactylus species (Perciformes: Polynemidae) characterized by a large black anterior lateral line spot, with descriptions of two new species

Nominal Polydactylus species characterized by a large black spot anteriorly on the lateral line, P. microstomus (Bleeker), P. sextarius mullani (Hora), P. sextarius sextarius (Bloch and Schneider), and P. zophomus Jordan and McGregor, are reviewed. Polydactylus zophomus, with 5 pectoral filaments, is synonymized under P. microstomus, and P. sextarius mullani, with 7 pectoral filaments, is elevated to species level (as P. mullani). Polydactylus microstomus and P. mullani together with P. sextarius (characterized by 6 pectoral filaments) are considered as valid species and redescribed accordingly. Two new species, P. malagasyensis and P. persicus, each with 6 pectoral filaments, collected from the east coast of Africa, including Madagascar and the Persian Gulf, are also described. Polydactylus sextarius and the 2 new species are characterized by 6 pectoral filaments. However, P. sextarius is distinguished from the latter by having lower gill raker counts (mode 28 vs. 31 in the latter) and an atrophied swimbladder (vs. well-developed). Polydactylus malagasyensis differs from P. persicus in having higher pectoral fin ray counts (14 vs. mode 12 in the latter), the palatines inwardly turned anteriorly (vs. straight), and a longer pectoral fin (mean 24% of standard length vs. 19%).

The principal caudal fin ray count ‐ a fundamental character in the galaxioid fishes

The principal caudal rays, usually defined as the two largest segmented unbranched fin rays in the caudal fin that lie above and below, and the segmented branched caudal rays that they enclose, have a consistent relationship to the caudal skeleton in galaxioid fishes, being those fin rays supported by the primitively ventral surface of elements in the caudal skeleton. They comprise rays supported by skeletal elements including, and posterior to, the parhypural and hypurals. The most anterior (or ventral) principal ray is supported by the parhypural while the posterior (or uppermost) principal ray lies immediately below the point at which the notochord emerges from the truncated posterior end of the last caudal vertebra. The consistent relationship to these skeletal elements suggests that the principal caudal fin ray count is a character of fundamental nature for the galaxioid fishes, giving it particular phylogenetic significance in that group.

Symphurus civitatium (Pleuronectiformes: Cynoglossidae), A Second Estuarine-Occurring Tonguefish off the Southeastern United States and Northern Gulf of Mexico

Two species of tonguefishes,Symphurus plagiusa (Linnaeus 1766) andSymphurus civitatium Ginsburg 1951, occur sympatrically and sometimes syntopically in shallow water habitats in North Carolina and Louisiana estuaries. In North Carolina, approximately 2% of 430 small (<75 mm SL) tonguefishes collected wereS. civitatium, while in Barataria Bay, Louisiana, this species was more abundant and cosmopolitan in distribution than wasS. plagiusa, comprising over 82% of 3,564 tonguefishes collected with a small beam trawl over a 2-yr period. Historical literature has regardedS. plagiusa as the only tonguefish species inhabiting inshore waters in both regions. Presence of a secondSymphurus species in shallow estuaries has been overlooked, most probably due to difficulties in identifying early post-settlement juveniles because both species have similar morphologies and overlapping dorsal-fin and anal-fin ray counts. Juveniles can be readily recognized by differences in number of caudal-fin rays (10 inS. plagiusa versus 12 inS. civitatium), especially when used in combination with pigmentation patterns and posterior extent of the jaws relative to the posterior margin of the lower eye. The most distinctive pigmentation difference between juveniles of these two species (allowing for accurate identifications of over 98% of juveniles) is the absence inS. civitatium (12–61 mm SL) of a series of melanophores overlying pterygiophore regions of the dorsal and anal fins on the blind side. This feature contrasts markedly with that of juvenileS. plagiusa (12–65 mm SL), which are characterized by two interrupted, diagonal series of dark chromatophores converging, but not merging, with posterior tapering of the body. Occurrence of two sympatric species of tonguefishes in estuarine environments in the northcentral Gulf of Mexico and southeastern U.S. potentially compromises results of earlier ecological and distributional studies that assumed presence of only a single tonguefish species in these regions.

Geophysical determination of the138La β−decay constant

The ${}^{138}\mathrm{La} {\ensuremath{\beta}}^{\ensuremath{-}}$ decay constant was determined geophysically. The isotopic growths of ${}^{138}{\mathrm{C}\mathrm{e}/}^{142}\mathrm{Ce}$ and ${}^{143}{\mathrm{N}\mathrm{d}/}^{144}\mathrm{Nd}$ were examined from ancient igneous crystalline rocks. For the Ce isotope measurement, a newly developed dynamic multicollector technique was applied. The crystallization age of the rocks was calculated to be $2037\ifmmode\pm\else\textpm\fi{}13$ Myr from the growth of ${}^{143}\mathrm{Nd}.$ From the age and the growth of ${}^{138}\mathrm{Ce},$ ${\ensuremath{\lambda}}_{\ensuremath{\beta}}$ of ${}^{138}\mathrm{La}$ was estimated to be $(2.37\ifmmode\pm\else\textpm\fi{}0.10)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}12} {\mathrm{yr}}^{\ensuremath{-}1}.$ This value is consistent with those of the latest two $\ensuremath{\gamma}$-ray counting data of lanthanum compounds within the analytical error.

Distribution ofGambusia(Poeciliidae) in a Southeastern River System and the Use of Fin Ray Counts for Species Determination

Recent collections from the Conasauga River system revealed the presence of Gambusia holbrooki, previously unreported in the Coosa River portion of the Mobile River drainage. We analyzed Gambusia specimens in 36 collections from the Conasauga River system to determine the relative distribution of G. affinis, G. holbrooki, or their hybrid progeny. We used gonopodial characters and ray counts from the anal and dorsal fins, which required reconciling differences among published accounts, to make species determinations. We counted all fin rays separately for dorsal and anal fins and recommend this method to clarify discrepancies among previous reports. This method yielded counts of seven dorsal and 10 anal rays for G. affinis and eight dorsal and 11 anal rays for G. holbrooki. Both species and their hybrids were collected in the Conasauga River system. Gambusia affinis is widespread in the Conasauga River system and is presumably native. Gambusia holbrooki currently has a limited distribution but appears to be expanding its range. We attribute the occurrence of G. holbrooki to human introduction.

Assessment of background hydrogen by the Monte Carlo computer code MCNP-4A during measurements of total body nitrogen.

The use of a hydrogen internal standard to enable the estimation of absolute mass during measurement of total body nitrogen by in vivo neutron activation is an established technique. Central to the technique is a determination of the H prompt gamma ray counts arising from the subject. In practice, interference counts from other sources--e.g., neutron shielding--are included. This study reports use of the Monte Carlo computer code, MCNP-4A, to investigate the interference counts arising from shielding both with and without a phantom containing a urea solution. Over a range of phantom size (depth 5 to 30 cm, width 20 to 40 cm), the counts arising from shielding increased by between 4% and 32% compared with the counts without a phantom. For any given depth, the counts increased approximately linearly with width. For any given width, there was little increase for depths exceeding 15 centimeters. The shielding counts comprised between 15% and 26% of those arising from the urea phantom. These results, although specific to the Swansea apparatus, suggest that extraneous hydrogen counts can be considerable and depend strongly on the subject's size.