Rib Pattern Research Articles

Thermo-hydraulic performance of rectangular channel roughened with combined semi-circular and triangular ribs

Ribs of different geometrical shapes are used on the surface for heat transfer enhancement. However, the combination of different shapes of ribs on the heat transfer surface is found less in literature. The objective of the present investigation is to design ribs roughness pattern of semi-circular, triangular, and hybrid ribs (combined semicircular and triangular ribs) on the bottom heated surface of the channel. Then, find optimum configuration and geometry of ribs pattern that has highest thermo-hydraulic performance. This combination of different shape of ribs pattern may be used for cooling of the heated channel such as in gas turbine blade, and high-temperature gas cooled reactors, etc. The rib pitch to rib height ratio (p/e) is considered in the range from 6.6 to 53.3 and Reynolds number in the range from 12,640 to 52,410. Turbulence model used for analysis is shear stress transport (SST) k-ω model. The effect of different geometry and configuration of ribs pattern on Nusselt number and friction factor are investigated and compared with that of the smooth channel. It is found that the Nusselt number (Nu) is maximum at p/e of 13.3 and friction factor (f) is maximum at p/e of 6.6 for all geometry of ribs pattern considered. Furthermore, Thermal enhancement factor (TEF) is determined for all geometry and configurations of ribs pattern. It is found that Thermal enhancement factor is maximum for hybrid ribs (1.34) at p/e of 13.3 and Reynolds number of 12,640 from the geometry and configuration of ribs pattern considered.

Shark Skin Inspired Riblet Microstructures As a Novel Solid-Liquid Triboelectric Nanogenerator for Energy Harvesting

Nature has provided a number of innovative inspirations for human beings to design artificial systems in order to mimic the excellent performance of existing biological systems. One of the most important and unexplored example in this regard is the shark skin. The surface of the shark skin consists of a three-dimensional rib pattern which displays exceptional super-hydrophobicity effect and drag reduction effect compared to the absolutely smooth skin textures. Inspired by this characteristic feature found in nature, a novel triboelectric nanogenerator (TENG) has been developed for harvesting electrical energy arising from the solid-liquid interface. By integrating the shark-skin patterns with polytetrafluoroethylene (PTFE), the as-fabricated biomimetic surface exhibits excellent super-hydrophobicity. Moreover, the presence of the shark skin structures on the surface potentially enlarges the contact area thus inducing better intimate contact and reducing the effect of residual liquid on the triboelectric output. Owing to the aforementioned facts, our bio-inspired TENG would generate more accurate signals and thereby be a new paradigm for wider range of applications.

Sub-Pixelated Color Realization of Reflective Electronic Display Using Partially Color-Addressable Technology

Partially addressable technology to realize a colorized image onto a glass substrate or plastic film in reflective electronic paper display is accomplished by the particle-moving method. This image panel includes upper and lower substrates with cells surrounded by rib patterns and filled with charged color particles. Mold substrate is prepared with the same condition as that of the lower substrate. The electric field between the mold and upper/lower substrates is used in this study, along with the image force of the conductive electrode. This addressable technology can be easily applied to any image panel, including transparent film. The feasibility of this technology is shown as a resultant reflective display panel with its fabrication process. We also ascertain that partially-addressed particles with a two-contrast color image are transferred from the mold substrate to the upper substrate of the panel via the particle-moving method.

Pseudoheptagonal Mosaic from the Hodja Ahmad Tomb, Samarkand

The pseudoheptagonal mosaic panel above the entrance to the mausoleum of Hodja Ahmad, Shah-i-Zindeh Necropolis in Samarkand, Uzbekistan consists of an intercrossed rib pattern on dark green background. It is a complex combination of eightfold rosettes with heptagons which enclose sevenfold stars. Analysis shows that it is based on a mixture of underlying 3.4.32.4 and 33.42 configurations, invisible in the final pattern. Eightfold elements are regular whereas the sevenfold ones are pseudoheptagonal approximations. Additional, larger-scale circles and festoons which result from the basic geometry, further enliven the pattern. The Hodja Ahmad mosaic may be understood as an attempt to develop further the heptagonal patterns based on the underlying 3.4.32.4 tiling of squares and triangles.

Morphological variability within the marine dinoflagellate Ornithocercus quadratus (Dinophysales, Dinophyceae) – evidence for three separate morphospecies

:The dinoflagellate genus Ornithocercus is comprised of 15 valid morphospecies that were morphologically characterised by extraordinary winglike lists. Species determination was based mainly on the morphology of the left sulcal list, which has great variability. Whether forma delimitation of Ornithocercus quadratus was possible on the basis of infraspecific variation of the left sulcal list was the subject of this study. Additional supportive morphological features (e.g. cingular lists, cingulum, ornamentation and cell body shape) were investigated. In considering infraspecific variability, the validity of previously published forms (and varieties) of the species was reviewed and compared with our results. A total of 247 specimens of five forms of O. quadratus from the Atlantic and Pacific Oceans were examined morphologically, using light and scanning electron microscopy. The range of morphological variation of the left sulcal list (e.g. shape and rib pattern) was evaluated for each form. On the basis of this analysis, the forms O. quadratus f. simplex and O. quadratus f. intermedia have to be treated as synonyms of O. quadratus f. assimilis. The species status of O. assimilis should be reinstated, and the form O. quadratus f. schuettii is proposed to represent a separate morphospecies.

Species Diversity and Structure of Wing Scales of Euploea and Papilio Butterflies from Phromlaeng, Nam Nao National Park, Phetchabun Province

This study focuses on species diversity of butterflies in the genera Euploea and Papilio in Nam Nao National Park. The butterflies were investigated every month for one year using insect nets. A total of 11 species, belonging to 2 genera and 2 families, were found. These were E. algea, E. camaralzeman, E. core, E. midamus, E. mulciber, E. radamanthus, E. sylvester, P. helenus, P. memnon, P. nephelus, and P. paris. The structure of the wing scales in different colour areas of 9 species was studied using a stereo microscope and a scanning electron microscope. The general structure of the wing scales of the butterflies of genus Euploea, independent of the colour it produces, is of longitudinal ridges, composed of tilted scutes, cross ribs that connect the ridges, and trabeculae, which link the cross ribs to the membrane of the wing scale’s upper lamina. In the Papilio species, there are 2 types of wing scales: one that exhibits blue-green iridescence and has wide-spaced ridges with concavities in between; and one displaying white, black, yellow, and red and has smaller widths between the ridges, with the space in between them containing a reticular pattern of cross ribs. The study of the wing scale microstructure of the butterflies in the Euploea and Papilio genera indicates that the patterns of the wing scale structure are genus-specific and that, despite showing similar colours, the wing scales are equipped with different mechanisms exemplifying diversity in structural coloration in nature.

Cover Fuel Cells 1/2018

Fuel CellsVolume 18, Issue 1 p. 1-1 Cover PictureFree Access Cover Fuel Cells 1/2018 First published: 26 February 2018 https://doi.org/10.1002/fuce.201870011AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Graphical Abstract The front cover shows a simplified representation of a planar SOFC stack assembly involving the cell lamination and interconnect plates under an applied load. A pattern of metal ribs on the interconnector makes contact with the porous ceramic current collector layer on the air side. These localised contacts are regions of increased stress on the cells and can cause damage if the stresses become too large. In this paper the mechanical response of an anode-supported cell to localised loads from ribs on an interconnector plate is simulated. The simulations show how the critical stress for initiating and propagating a crack is reached by increasing applied pressure with the anode support in both an oxidized and reduced state. Simulations on the contacting geometries are also performed for optimisation purpose. More details can be found in the Original Research Paper by Zhangwei Chen et al., DOI: 10.1002/fuce.201700128. Volume18, Issue1February 2018Pages 1-1 RelatedInformation

Numerical Study of Solid Oxide Fuel Cell Contacting Mechanics

AbstractAssembly of a planar solid oxide fuel cell (SOFC) or solid electrolyzer (SOE) stack involves the lamination of cells and interconnect plates under an applied load. In most designs a pattern of ribs on the interconnector makes contact with a porous ceramic current collector layer on the air side. These localized contacts are regions of increased stress on the cells and can cause damage if the stresses become too large. In this paper the mechanical response of an anode‐supported cell to localized loads from interconnector ribs is simulated. The simulations show that the critical stress for initiating and propagating a crack in the electrolyte (∼300MPa for a 10 μm thick electrolyte) is reached when the interconnector displacement reaches 20 μm (after touching the cathode) with reduced support, or 30 μm when in an oxidized state. The difference is due to the lower stiffness of the reduced support. The residual compressive stress in the electrolyte layer has a major protective effect for the electrolyte. It is concluded that fracture is very unlikely for a geometrically perfect contact, but if the contact is non‐uniform due to manufacturing variability in the contact plate or cell, local displacements >∼20 μm can be dangerous. The simulations are used in an example of contacting geometry optimization.

Morphological evolution of the bivalvePtychomyathrough the Lower Cretaceous of Argentina

AbstractThe complex morphological evolution of the bivalvePtychomyathroughout the well-studied Agrio Formation in the Neuquén Basin (west-central Argentina, lower/upper Valanginian–lowest Barremian) constitutes an ideal opportunity to study evolutionary patterns and processes occurring at geological timescales. Ptychomyais represented in this unit by four species, the morphological variation of which needs to be temporally assessed to obtain a thorough picture of the evolution of the group. Here we use geometric morphometrics to measure variation in shell outline, ribbing pattern, and shell size in these species. We bracket the ages of our samples using a combination of ammonoid biostratigraphy and absolute ages and study the anagenetic pattern of evolution of each trait by means of paleontological time-series analysis and change tracking. We find that evolution inPtychomyais mostly speciational, as the majority of traits show stasis, with the exceptions of shell size inP. coihuicoensisand shell outline inP. windhauseni, which seem to evolve directionally toward larger and higher shells, respectively.Ptychomyadisplays changes in its average morphology and disparity, which are the result of a mixture of taxonomic turnover and mosaic evolution of traits. Pulses of speciation would have been triggered by ecological opportunity, as they occur during the recovery of shallow-burrowing bivalve faunas after dysoxic events affecting the basin. On the other hand, the presence of directional patterns of evolution inP. coihuicoensisandP. windhauseniseems to be the result of a general shallowing-upward trend observed in the basin during the upper Hauterivian–lowest Barremian, as opposed to the cyclical paleoenvironmental stability inferred for the early/late Valanginian–early Hauterivian, which would have prompted stasis inP. koeneniandP. esbelta.

Organs and tissues of Rhynie chert plants.

The Early Devonian Rhynie chert and the nearby Windyfield chert contain the oldest in situ preserved terrestrial ecosystem. Two of the seven species of anatomically preserved land plants had naked axes, one an axis with a more or less regular pattern of short-longitudinal ribs, two species had spiny axes and one species had small leaf-like appendages. All plants mainly consist of parenchymatous tissues. In some species, conducting elements comprise uniformly thickened thick-walled cells resembling hydroids of larger bryophytes, whereas others have real tracheids with annular and/or spiral secondary wall thickenings. True phloem has never been demonstrated but in all species the thick-walled water-conducting cells are encircled by a zone of thin-walled cells without intercellular spaces. The cortex is differentiated into two or three zones and forms the major part of the axes; in one species the cells of the middle cortex are sclerified. Some species have a hypodermis. In all species the epidermis is covered by a well-developed cuticle. Sporangia are known from all species. Sporangia are spindle-shaped, lobed or kidney-shaped and attached terminally or laterally with a short stalk. Gametophytes of four species have been described. Gametophytes are unisexual, isomorphic but much smaller than the sporophytes.This article is part of a discussion meeting issue 'The Rhynie cherts: our earliest terrestrial ecosystem revisited'.

Experimental and numerical investigation of heat and fluid flow in a square duct featuring criss-cross rib patterns

This paper presents findings from experimental and numerical study of heat and fluid flow in a straight square duct featuring rib turbulators in a criss-cross pattern formed by 45° angled rib turbulators. Two ribbed configurations with criss-cross pattern – Inline and staggered, have been studied where the baseline case was smooth duct with no heat transfer enhancement feature. Detailed heat transfer coefficients were calculated using transient liquid crystal thermography by employing 1-D semi-infinite conduction model. Heat transfer and pressure drop measurements were carried out for Reynolds number ranging from 30,000 to 60,000. For understanding of heat transfer enhancement mechanism, numerical investigations were carried out using SST k-ω turbulence model. Numerical predictions of near-wall fluid dynamics and turbulent transport has been presented in conjunction with experimentally obtained detailed heat transfer coefficients to demonstrate the heat transfer characteristics of ribbed duct. Nusselt numbers normalized with respect to Dittus-Boelter correlation for developed turbulent flow in circular duct varied between 2.7 and 3.1 for inline and staggered configurations and the thermal hydraulic performance varied between 1.2 and 1.5 for the range of Reynolds number investigated.

PENGARUH PERMUKAAN ALUR KEMBANG (TREAD PATTERN) BAN TYPE RADIAL PLY TERHADAP ROLLING RESISTANCE

Rolling Resistance is a resistance to the wheels that will and have been rolling due to the force of friction between the wheels with the road surface of the wheel. Rolling resistance is influenced by four factors, that is vehicle weight, road surface, transmission, and tires. This study usefull to determine the influence of tread pattern surface to force and coefficient rolling resistance, tire surface contact area and tire pressure value. In this study using motorcycle tires with size 90/90-17. The tire used is a tire with RIB tread pattern (straight groove) and LUG tread pattern (zig-zag groove). Each type of RIB and LUG tread pattern used each of two tires that is the type of simple tread pattern and the complex tread pattern. From the results of the study showed that the tire with a simple tread pattern will produce a small force of rolling resistance but will result in a larger surface tire surface contact than the tire with the complex tread pattenr. While for the tire with the type complex tread pattern has a greater pressure value that will produce a great rolling resistance force. For tires get the best rolling resistance force is the tire with a simple LUG tread pattern of 10.234 N and followed by a tire with a simple RIB tread pattern type of 10.563 N.
 Keywords: tread pattern, rolling resistance, rib, lug.

리브를 가진 장섬유 복합재료 커버 플레이트의 최적설계

일방향 탄소섬유 복합재료는 복잡한 성형 공정과 낮은 드레이핑능을 보여 비교적 단순한 형태의 구조물 제작에 제한적으로 사용되어 왔으나, 최근 이를 해결하고자 성형성과 생산효율이 우수한 장섬유 복합재료(Long Fiber Prepreg Sheet; LFPS)가 제안되었다. 본 연구에서는 단순한 성형 공정과 높은 성형 정밀도를 갖는 LFPS를 활용하여 전자 기기용 커버 플레이트 설계를 수행하였다. 설계에 앞서 리브 구조가 적용되는 대상 구조물을 8-inch 태블릿 PC 제품의 뒷 커버로 선정하였다. 해당 구조물에 평판에 적용되는 대표적인 하중 조건을 선정하여 유한요소해석에 적용하였고, 이를 활용하여 리브 구조물의 패턴과 리브 형상 변화에 따른 구조물의 구조 강성을 확인하였다. 해석 결과 제한된 부피 내에서 최적의 리브 패턴과 형상을 확보하였으며, 리브 폭이 균일하지 않은 경우가 균일한 경우에 비해 6~10% 처짐량이 감소함을 확인하였다. Carbon fiber reinforced composites have light weight and high mechanical properties. These materials are only applicable in limited shape structure cause by complex curing process and low drapability. To solve this problem, Long Fiber Prepreg Sheet (LFPS) has been proposed. In this research, electric device cover plate was selected and designed by using LFPS. Before the design process, we analyzed the target structure to which the rib structures were applied. And 8-inch tablet PC product was selected. For FE analysis, simple loading and boundary conditions were applied. Stiffness of rib structure was investigated according to the rib pattern and shape changes. Rib pattern and shape were selected based on fixed volume condition analysis results. And uneven rib width model was selected for the best case whose deflection was reduced 6~10% than uniform rib model.

Taxonomy of the bivalve Ptychomya in the Lower Cretaceous of the Neuquén basin (west‐central Argentina)

AbstractIn the Lower Cretaceous Agrio Formation, Neuquén Basin (west‐central Argentina), the highly variable genus Ptychomya Agassiz has challenged traditional taxonomists for over a century. Here we apply a previously outlined quantitative protocol in order to settle the taxonomy of the genus based on specimens recorded from the base to the top of the Agrio Formation. The shell outline and ribbing pattern, two prominent external features of the valves, were quantified using geometric morphometric measurements of closed and open outlines, respectively. Morphological groupings were identified using model‐based clustering, and the presence of significant morphological gaps between them was statistically tested. Our results show that the variation historically attributed to a single species, namely Ptychomya koeneni Behrendsen, corresponds to intra‐ and interspecific variability of at least four species, one of which was previously unknown (Ptychomya esbelta sp. nov.) whereas another was regarded as a subspecies of P. koeneni, namely Ptychomya windhauseni Weaver. We were also able to confirm the specific rank of Ptychomya coihuicoensis Weaver and the presence of P. koeneni in the upper Hauterivian of the Agrio Formation. This study represents a significant improvement over the previous state of knowledge of the genus Ptychomya in the Andes of Argentina, enhancing its biostratigraphical usefulness and palaeobiogeographical significance, and may serve as a model for the study of other poorly known bivalve faunas from other Andean basins of South America.

Adverse Fetal and Neonatal Outcome and an Abnormal Vertebral Pattern: A Systematic Review.

The human vertebral column has a stable number of vertebrae and ribs, which is presumably the result of evolutionary selection. An association between an abnormal vertebral pattern, especially in the cervical region, and congenital anomalies or adverse fetal outcome has been reported. The aim of this study was to review the current literature concerning an abnormal vertebral pattern and prevalence of cervical ribs in healthy subjects and in subjects with adverse outcome. Scientific databases were searched systematically. Studies assessing the number of vertebrae and/or ribs were included, and data concerning anomalies and outcome were extracted. Thirty-nine studies including 75,018 healthy subjects and 6130 subjects with structural or chromosomal anomalies or adverse outcome were selected. The majority of these studies focused on the prevalence of cervical ribs. The prevalence of cervical ribs was considerably higher in fetuses with adverse outcome, including aneuploidies, compared with healthy individuals in the vast majority of studies. Studies suggest an association between cervical ribs and other structural anomalies. These results demonstrate that detailed assessment of the fetal vertebral column, especially of the cervicothoracic region, could provide valuable information regarding fetal and neonatal prognosis. Based on the available evidence, the application of 3-dimensional (3D) ultrasound to assess the vertebral column and ribs, in particular the cervical region, warrants further research. Prenatal assessment of the ribs and vertebral pattern by 3D ultrasound, which is currently not routinely performed, might be useful in the assessment of the fetus, because this can predict fetal and neonatal outcome in some cases.

Cisnerospira(Brachiopoda, Spiriferinida), an atypical Early Jurassic spire bearer from the Subbetic Zone (SE Spain) and its significance

AbstractThe order Spiriferinida represented a significant group whose extinction is linked to the early Toarcian mass extinction event. The genusCisnerospiraManceñido, 2004, conspicuous representative of this group in the Early Jurassic of the western Tethys, is analyzed from a systematic standpoint, grounded mainly on evidence from the Subbetic domain, and its initial diagnosis is revised accordingly. A definitive suprageneric position within the subfamily Paralaballinae is formally proposed in the light of new data herein provided. Both external and internal diagnostic features and the generic and intraspecific variability are described through the analysis of theCisnerospiraspecies recorded in the easternmost Subbetic area, i.e.,Cisnerospira adscendens(Deslongchamps, 1858), C. aff.adscendens, C. angulata(Oppel, 1861), andC.?sylvia(Gemmellaro,1882). In addition, their interrelation with other records from several Tethyan basins is addressed, and the generic spectrum has been extended to include several species with high morphological affinity. This characterization thus contributes to clarify certain ambiguities in the systematics of the spiriferinids, which entails a complex taxonomy mainly based on the external features, where the ribbing pattern was given foremost classificatory value due to the lack of more reliable generic diagnostic criteria. Furthemore, a morphofunctional analysis performed inCisnerospirareveals a presumable epibenthonic libero-sessile way of life, and two alternative adaptive strategies are discussed: resting on and/or sticking in substrates with different degree of consolidation, providing a significant hydrodynamic stability to the shell.

Thermo-Hydraulic Performance Evaluation Using W-Discrete Rib in Solar Air Heater

Background/Objective: This paper have more emphasis towards augmentation of solar air duct thermal efficiency. Flow of heat restricted by sub-layer of laminar flow is the major criterion to reduce the thermal efficiency of solar air duct. Methods/Statistical Analysis: For breaking laminar sub-layer artificial roughness with pattern of W-Discrete geometry has been developed. With all consideration of different previous geometries as a pattern of artificial roughness W-Discrete ribs have best thermo-hydraulic performance. During experimental investigation different parameter taken are Reynolds number of 14000-4000, duct aspect ratio of 8, angle of attack of 45° and relative roughness height of 0.03375. Findings: Maximum increment of Nusselt number along with friction factor found in order of 2.79 and 1.98 as compare to smooth plate. Increase in heat transfer enhancement rate is obtained to be 2.35 times for W-discrete up and 2.60 times for W-discrete down rib pattern. Simultaneously with the consideration of smooth plate data results have been evaluated. Application/Improvements: Now a day's various solar collection and conversion systems are used like air heaters for crop drying, solar air conditioning and industrial applications. Solar collector is most important component that accounts for major portion of system cost comprising and utilization as a whole.

Ribbed bedforms on palaeo-ice stream beds resemble regular patterns of basal shear stress (‘traction ribs’) inferred from modern ice streams

Rapidly-flowing ice streams are an important mechanism through which ice sheets lose mass, and much work has been focussed on elucidating the processes that increase or decrease their velocity. Recent work using standard inverse methods has inferred previously-unrecognised regular patterns of high basal shear stress (‘sticky spots’ >200 kPa) beneath a number of ice streams in Antarctica and Greenland, termed ‘traction ribs’. They appear at a scale intermediate between smaller ribbed moraines and much larger mega-ribs observed on palaeo-ice sheet beds, but it is unclear whether they have a topographic expression at the bed. Here, we report observations of rib-like bedforms from DEMs along palaeo-ice stream beds in western Canada that resemble both the pattern and dimensions of traction ribs. Their identification suggests that traction ribs may have a topographic expression that lies between, and partly overlaps with, ribbed moraines and much larger mega-ribs. These intermediate-sized bedforms support the notion of a ribbed bedform continuum. Their formation remains conjectural, but our observations from palaeo-ice streams, coupled with those from modern ice masses, suggest they are related to wave-like instabilities occurring in the coupled flow of ice and till and modulated by subglacial meltwater drainage. Their form and pattern may also involve glaciotectonism of subglacial sediments.

The Study of the Structural Colouration Observed in the Papilio crino Fabricius, 1792 Wings

The research on nano-photonics has been on the increase recently. Among the materials that exhibit stunning optical properties are the nano-photonic materials found in nature such as those on butterfly wings. The wing scales of papilio crino was analysed using the Scanning Electron Microscopy (SEM), UV-Vis-NIR spectrometer, and Optical Microscopy (OPM). Under the OPM, the wing scales was imaged both in normal and polarized (45°) light. The SEM images reveal concave surfaces separated by repeating pattern of ridges and cross ribs. The variation in colour across the concave surface modulation was evident from the optical microscopy images. Through the numerical simulation and CIELab colour space, it was shown that the green colour seen on the wings is a combination of yellow and blue light reflected from different microscopic regions on the wing concave surface. This shows application in the bio-mimicks of retroflection sensors for the detection and classification of optical systems.

Seven new species of Paleanotus (Annelida: Chrysopetalidae) described from Lizard Island, Great Barrier Reef, and coral reefs of northern Australia and the Indo-Pacific: two cryptic species pairs revealed between western Pacific Ocean and the eastern Indian Ocean.

Morphological investigation into the paleate genus Paleanotus Schmarda 1861 of the family Chrysopetalidae from northern Australian coral reefs, primarily Lizard Island and outlying reefs, included a complex of very small, slender individuals (length < 5 mm). This complex resolved into 7 new species, described herein: Paleanotus inornatus n. sp., P. adornatus n. sp., P. chrysos n. sp., P. aquifolia n. sp., P. latifolia n. sp., P. silus n. sp., and P. silopsis n. sp. A key is provided to the new species and Paleanotus distinguished from Treptopale and Hyalopale, two closely related genera. Diagnostic features of the apical structure and shape of the notochaetal main paleae plus median paleae shape and raised rib pattern, differentiates each species from the other. Gametous states are described. Two cryptic species pairs (Paleanotus silopsis n. sp. and P. silus n. sp.; Paleanotus aquifolia n. sp. and P. latifolia n. sp.) were identified. In each case one species is restricted to either the NE or NW Australian coast. In each pair the most eastern point for the NW Australian species range occurs at Darwin, western Arnhemland, Northern Territory. Additional material for each species pair extends their respective ranges northwards: NW Australia to Thailand, Andaman Sea, eastern Indian Ocean or NE Australia, Great Barrier Reef to the Philippines, western Pacific Ocean. Cryptic morphology and potential genetic diversity is discussed in Paleanotus inornatus n. sp. and P. adornatus n. sp. that possess overlapping widespread distribution patterns across northern Australia and Indo-Pacific reefs. The smallest bodied taxon, Paleanotus chrysos n. sp. is the only species with a Coral Sea range encompassing Lizard Island, Heron Island and New Caledonia.