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The trunk canal of fishes is contained within a series of lateral line ( LL) scales. To categorise LL scale structural types, and determine their distribution, an analysis of original data was undertaken using light and scanning electron microscopy in combination with a literature survey from over 1,000 species representative of most orders of bony fishes. Our categorisation of LL scales is based on the relationship between the tube, or ossified trunk canal segment, and associated scale. Tubular-Scalar LL scales consist of a distinguishable tube and elasmoid scale in scale pockets. Four types occur only in species with elasmoid scales. Integrated LL scales do not develop in scale pockets, and their tube is enclosed or extended by a non-elasmoid scale or spines. Integrated 1 and 2 LL scales co-occur with ganoid and calcidermoid scales, and Integrated 3 LL scales occur when common scales are absent or elasmoid. Tubular LL scales are tubes only, occurring mainly in scaleless species or with calcidermoid and elasmoid scales. Non-Tubular LL scales are composed only of a scale, co-occurring mainly with cycloid scales. There is consistency of LL scale type in many orders, families and genera and the presence of different types within taxa can be meaningful. [ABSTRACT FROM AUTHOR]

Coloration in three of four species of the genus Neurergus including N. microspilotus is characterized by the presence of yellow spots on a dark skin, but there is no available information about changes in spot configuration, speed of development and degree of association between melanophore-free region and the lateral line. In this study, spot numbers, spot circularity, spot size and spot asymmetry were studied during larval to adult growth in N. microspilotus during July 2012 to June 2015. The mean numbers of spots increased during the late larval stage till postmetamorphic period from 13.33 ± 3.77 to 22.53 ± 4.09 and reached 42.62 ± 4.06 in adults. At the same time, the extent of spots gradually decreased in size from 5.80 ± 1.00 to 3.57 ± 0.97 mm2 and reached 3.55 ± 1.42 mm2 in adults, but the spot circularity increased from 0.48 ± 0.23 to 0.78 ± 0.49 and reached 0.80 ± 0.15 in adults. In adults, the numbers, circularity, size and asymmetry of spots remain stable with little but non-significant changes during the study period. Histological study shows that formation of a melanophore-free region correlates with the development of the lateral line receptors. This study demonstrates that the effects of lateral line on chromatophores persist through middle larval stages but diminish as metamorphosis completes. [ABSTRACT FROM AUTHOR]

Voronina, E.P. and Hughes, D.R. 2011. Types and development pathways of lateral line scales in some teleost species. - Acta Zoologica (Stockholm) 00: 1-13. A comparative study of lateral line scales ( lls) in nine teleost species was undertaken to trace their ontogenetic structural changes. Three universal characters were used to describe and classify definitive and developing lls. The four main structural types in teleosts are represented. In adult fish, lls are the same structural type in all parts of lateral line in any one specimen, but number of tubules and their orientation may vary. In juvenile fish, except for one species, the structural type of every lls changes with growth, and this process progresses along the lateral line in the direction of development typical for the species. Definitive structural type of the lls is not determined by common scale type and size, presence or absence of nerve foramen on lls, scale overlapping or time of initiation of scales and trunk canal. Development pathways are proposed in which terminal states correspond to the final development of the most complex lls type in Cyprinus carpio, Carassius carassius, Oncorhynchus mykiss, Diplodus annularis and Mullus barbatus. The intermediate states of these pathways correspond to other types of lls as examples of pedomorphosis in Perca fluviatilis, Sander lucioperca, Symphysodon aequifasciatus and Hippoglossoides platessoides. [ABSTRACT FROM AUTHOR]

The morphology and growth of selected lateral line organs of the rainbow trout (Oncorhynchus mykiss) are described. Canal neuromasts of the infraorbital and operculo-mandibular canal of three different-sized trout have been examined by light microscopy. The number of neuromasts and pores, as well as their distribution, is constant in all sizes of fish. However, the area and estimated number of hair cells (HC) of the examined neuromasts increases with size and with a correlation coefficient ... of 0.90 and 0.87, respectively. It was found that area and estimated hair cell number of neuromasts increase 6-fold in fish from 10 to 30 cm total length (TL). Based on calculation of the hair cell number in small and large fish, a net addition of 1 and 6 HC per day is suggested for IO and OM neuromasts, respectively. [ABSTRACT FROM AUTHOR]

The morphology of the lateral-line system of the nine-spined stickleback (Pungitius pungitius) and the three-spined stickleback (Gasterosteus aculeatus) has been studied. In the nine-spined stickleback, a preopercular, infraorbital, supraorbital, postotic and peduncular canal can be identified on both sides of the body. Replacement lines are found as a continuation of the preopercular and infraorbital canal. In addition, lines of free neuromasts are found on the mandible and trunk. An accessory line is present above and below the peduncular canal. The presence of both canals and accessory lines on the peduncle suggests that the peduncle in this species has important sensory functions. No canals are found in the three-spined stickleback. Instead, replacement lines corresponding to the canals can be identified on the head. Accordingly, the lateral-line system of the three-spined and the nine-spined stickleback has a different structure. The lateral-line system of both species shows signs of specialization but the three-spined stickleback has a more specialized lateral-line system than the nine-spined stickleback. [ABSTRACT FROM AUTHOR]

The morphology of the parietal shield of the Carboniferous osteolepiform Megalichthys laticeps is described. Of special note are the following features, none of which have hitherto been observed in other members of the group: each intertemporal section of the lateral-line canal system gives off a large, backwardly directed tube which enters the posterior part of the ipsilateral parietal bone where it becomes highly ramified; anterolaterally each intertemporal bone possesses an irregularly shaped and forwardly directed projection the frontoderrnosphenotic process which is traversed by the intertemporal section of the lateral-line canal system. In addition, evidence is offered that Megalichthys laticelis was equipped with a paired extratemporal bone as well as a tripartite extra- scapular series of exoskeletal elements; also, that the presence of the extratemporal bone most likely was correlated with the configuration of the subjacent part of the endocranium; and, finally, that no appreciable movement occurred between the anterior and posterior cranial divisions. [ABSTRACT FROM AUTHOR]