Broken River Research Articles

Environmental DNA analysis confirms extant populations of the cryptic Irwin\u2019s turtle within its historical range

BackgroundApproximately 50% of freshwater turtles worldwide are currently threatened by habitat loss, rural development and altered stream flows. Paradoxically, reptiles are understudied organisms, with many species lacking basic geographic distribution and abundance data. The iconic Irwin’s turtle, Elseya irwini, belongs to a unique group of Australian endemic freshwater turtles capable of cloacal respiration. Water resource development, increased presence of saltwater crocodiles and its cryptic behaviour, have made sampling for Irwin’s turtle in parts of its range problematic, resulting in no confirmed detections across much of its known range for > 25 years. Here, we used environmental DNA (eDNA) analysis for E. irwini detection along its historical and contemporary distribution in the Burdekin, Bowen and Broken River catchments and tributaries. Five replicate water samples were collected at 37 sites across those three river catchments. Environmental DNA was extracted using a glycogen-aided precipitation method and screened for the presence of E. irwini through an eDNA assay targeting a 127 base pair-long fragment of the NADH dehydrogenase 4 (ND4) mitochondrial gene.ResultsElseya irwini eDNA was detected at sites within its historic distribution in the lower Burdekin River, where the species had not been formally recorded for > 25 years, indicating the species still inhabits the lower Burdekin area. We also found higher levels of E. iriwni eDNA within its contemporary distribution in the Bowen and Broken Rivers, matching the prevailing scientific view that these areas host larger populations of E. irwini.ConclusionsThis study constitutes the first scientific evidence of E. irwini presence in the lower Burdekin since the original type specimens were collected as part of its formal description, shortly after the construction of the Burdekin Falls Dam. From the higher percentage of positive detections in the upper reaches of the Broken River (Urannah Creek), we conclude that this area constitutes the core habitat area for the species. Our field protocol comprises a user-friendly, time-effective sampling method. Finally, due to safety risks associated with traditional turtle sampling methods in the Burdekin River (e.g., estuarine crocodiles) we propose eDNA sampling as the most pragmatic detection method available for E. irwini.

The Broken River

The Broken River

Trilobites of the suborder Illaenina from the Silurian of north Queensland, Australia

AbstractThe trilobite fauna of the middle Silurian (Telychian to possibly earliest Sheinwoodian) Tomcat Creek limestone in the Broken River Province of north Queensland is dominated by the suborder Illaenina, including illaenimorphs (Illaeninae and Bumastinae) and members of the Scutelluidae. Scutelluidae are most diverse, with eight genera, of whichDolabrapex,Iotoryx,Perizostra, andQuintoniaare new.Perizostrais the first scutelluid with a cephalon that may be described as of phacomorph appearance. Illaenimorphs are represented by three genera, includingOpsypharus, which is regarded as a senior synonym ofParacybantyxbut distinct fromFailleanawith which it has been placed in synonymy by some authors. Thirteen species are new:Cybantyx?ergodes,Opsypharus pandanensis,Australoscutellum talenti,Dolabrapex acomus,Illaenoscutellum psephos,Iotoryx clarksoni,Japonoscutellum mawsonae,J. drakton,J. fractum,Kosovopeltis avita,Perizostra campbelli,Quintonia arata, andQ. pavo. A species ofStenopariais placed in open nomenclature. The species ofAustraloscutellum,Illaenoscutellum, and possiblyKosovopeltisare the oldest known representatives of those genera. These genera andJaponoscutellumare also common in faunas from limestones of Wenlock to Ludlow age in central western New South Wales, reflecting the similarity in lithofacies. The monotypic Late Ordovician genusCraigheadia, which has been regarded as a scutelluid, belongs to the Lichidae and is probably a junior synonym ofLeiolichas.

Quartz types of the Eocene Broken River Formation, Mount Somers, South Island, New Zealand

ABSTRACTQuartz arenites are a very common geological feature on the South Island of New Zealand. The provenance of the quartz grains that form these arenites is not well constrained because standard point-counting techniques do not provide enough detailed information. In this study we distinguish different quartz types using scanning electron microscopy–cathodoluminescence combined with standard optical microscopy on the same individual quartz grains. This is done on a suite of samples collected from shallow marine quartz arenites of the Paleocene–Eocene Blondin Sand Member of the Broken River Formation (Eyre Group) at Mt Somers in the Canterbury basin on the South Island of New Zealand. Our results show that the volcanic quartz grains were derived from local volcanic source rocks, whereas metamorphic quartz grains may have been derived from either local source rocks of the Torlesse Supergroup or from distant metamorphic sources rocks via longshore transport. Plutonic quartz grains were exclusively derived by long-distance transport. Warm and humid climatic conditions and the presence of humic acids in the associated coal-forming depositional environment probably increased the proportion of quartz in the sampled rocks.

River network completion without height samples using geometry-based induced terrain

We present an improved method for connecting broken river segments by incorporating segment geometry into the induced terrain approach. The reconnection problem is important in aerial photography. Canopies and clouds cover parts of rivers, and a complete river network is necessary for transportation, land-use planning, and floodplain control. Our previously presented induced terrain approach guarantees that the global network topology is hydrologically consistent. However, it assumes many reliable height samples, which may be unavailable because of extensive view obstacles or gentle surfaces, to reconstruct the induced terrain surface. In this paper, we exploit river segment geometries to generate the induced terrain. We assign lowest heights to the known river locations, and higher and higher heights for locations further and further away. Since areas radiating from segment tips tend to be where a river is broken, we assign relatively small heights to these areas, so as to favor water flow toward them in the subsequent river derivation. On average, such a tip-biased model improves reconnection accuracy by five percentage points (which is 40% of what we would have been corrected if we had had rich height samples covering 10% of the terrain cells) over the intuitive baseline model in which the height of a location increases with its distance from the respective nearest river location, without considering the potential effect of segment tips as the tip-biased approach.

Impacts of native forest harvesting on flows into the Murray–Darling Basin system

Recent drought in Australia has shown the importance of inflow into the Murray–Darling Basin from forested catchments in high-rainfall areas. Concern has been expressed that native forest logging could, by leading to regrowth forests, diminish this inflow. This reflects that at least one eucalypt community has a water use in which regrowth water yield is, for a given annual rainfall, less than that from ‘old-growth’ forest. Available data sets showing the relation between forest age, annual rainfall and water yield from forested catchments were used to select the best of four models of age-related water yield from forests. Commercial forests across the entire Murray Darling Basin were categorised by productivity and by location in rainfall bands. Using assumptions as to the distribution of age classes, the impact of native forest harvesting on water yields was compared with having all ‘old-growth’ in these forests. The results showed that for most of the Murray–Darling Basin, native forest logging would increase water yields by a small amount. Areas with potential for decreasing yield were the high-rainfall catchments of the Goulburn–Broken River, the Ovens–Kiewa River and the Upper Murray River. The results show that a cessation of harvesting would lead to a small decrease in flow before flows increased after about twenty years. Potential gains in water yield could be substantial but would take long periods to achieve and would be dependent on a lack of natural disturbance that could result in forest regeneration. The analysis showed that there is probably an optimal level of wood and water production, but the data are inadequate to determine that. There is a need for considerable work in forest hydrology if such questions are to be answered.

Sedimentology and structure of the Malvern Hills Coal Mine, Canterbury, New Zealand

The Malvern Hills Coal Mine provides an opportunity to gain insight into the stratigraphy and sedimentology of the Broken River Formation while addressing the complex deformation of range-front tectonics. An up-to-date geological map, stratigraphic columns and cross-sections have led to a greater understanding of both the mine and regional geology. The stratigraphy reflects a transgressive sequence: the Broken River Formation comprises fining-upwards cycles of flaser- and lenticular-bedded quartz sandstones and carbonaceous mudstones and coal seams representing a coastal swamp environment. Cross-bedded marine quartz sandstones of the overlying Conway Formation are typical of bar or dune settings, and lenses of tidal sedimentation reflect a lower intertidal–subtidal environment. NW–SE compression resulted in D1 tilting and block-faulting along range-front structures. Subsequently, D2 conjugate strike-slip shears bisect the mine forming a deformation wedge. Inside this, D3 folding about NE–SW hinges and D4 listric break-out faulting of the folds has resulted in sheared anticline-syncline pairs.

Heliolitine tabulate corals from Late Ordovician and possibly early Silurian allochthonous limestones in the Broken River Province, Queensland, Australia

Dixon, O.A. & Jell, J.S., iFirst article. Heliolitine tabulate corals from Late Ordovician and possibly early Silurian allochthonous limestones in the Broken River Province, Queensland, Australia. Alcheringa, 1–30. ISSN 0311-5518. Coral faunas of Late Ordovician (Ashgill) and possibly early Silurian age are present in allochthonous limestone blocks incorporated in debris flow deposits in the Broken River Province of north Queensland. The limestones occur in the Carriers Well Formation and Crooked Creek Conglomerate, which now lie within structurally deformed fault slices, and are evidence of the existence of a former carbonate platform of this age situated to the west. The fauna from the Carriers Well Formation includes 15 taxa belonging to the heliolitine coral families Heliolitidae, Pseudoplasmoporidae, Plasmoporidae, Plasmoporellidae and Sibiriolitidae. New taxa present are Wairunalites greeni gen. et sp. nov. and Plasmoporella marginata sp. nov. The fauna includes other species belonging to Heliolites, Plasmoporella and Sibiriolites in common with Late Ordovician faunas of New South Wales, central Asia and northern China. A limestone block in the Crooked Creek Conglomerate contains a few non-diagnostic heliolitine corals, together with rugosan, favositine and halysitine corals similar to those in the blocks of the Carriers Well Formation, but it also contains several alveolitine tabulates suggesting a possible early Silurian age.

Collisional accretion of a Late Ordovician oceanic island arc, northern Tasman Orogenic Zone, Australia

A distinctive Late Ordovician volcano-sedimentary terrane, embracing the Carriers Well Formation and Everetts Creek Volcanics and dismembered slivers now structurally intercalated in the adjoining Wairuna Formation, is located within the Broken River Province of the northern Tasmanides. It abuts a basement of mafic–ultramafic rocks (Gray Creek Complex) and overlying Early Ordovician deep marine sedimentary and volcanic strata (Judea Formation) which host tonalitic plutons. The terrane lies at the western, inboard-margin of the Camel Creek Subprovince, a broad tract of multiply deformed mid-Paleozoic turbidites with minor basalt and chert variously interpreted as the infill of a backarc basin or an accretionary wedge. U–Pb dates from detrital zircon indicate a maximum Late Silurian age for siliciclastic rocks from the previously undated Wairuna Formation. Geochemistry of volcanic rocks from the volcano-sedimentary terrane show them to be largely of mafic to intermediate compositions of calc-alkaline affinity, comparable with broadly coeval Macquarie Arc volcanic suites of the southern Tasmanides. Trace-element systematics identify a subduction relationship for the volcanic suite and V/Ti employed as a discrimination tool identifies the terrane as representing an oceanic island arc, consistent with its sedimentary facies which include volcaniclastic mass flow deposits, limestone, and radiolarian chert. Continent-derived sandstone in the sedimentary assemblage, confirmed by the ages of detrital zircon from a sandstone sample from the Carriers Well Formation, indicates that the oceanic island arc developed proximal to the Late Ordovician continental margin of East Gondwana. Its nature and location bear on the tectonic setting of the entire Camel Creek Subprovince, for which interpretation as an Early Silurian–Early Devonian accretionary wedge is favoured. Collision of the island arc with the continental margin, and associated deformation of part the intervening oceanic crustal tract, now represented by the Gray Creek Complex and its sedimentary cover (Judea Formation) registers the initiation of subduction accretion in late Early Silurian (Llandoverian) time. It marks early-stage orogenesis in the Broken River Province, accurately timed by stratigraphic relationships in the basinal succession developed in the Graveyard Creek Subprovince immediately to the west of the arc assemblage. Tectonism was regionally developed in north Queensland at this time, coeval with the Benambran Orogeny of the Lachlan Orogen in which the Macquarie Arc was likewise accreted to the East Gondwana margin. Benambran orogenesis marks a general phase of shortening, and removal by subduction, of oceanic crust and inversion of continent-derived overlying sedimentary cover along the East Gondwana margin.

Time-space evaluation of the tectono-metallogenic evolution of the northern Tasman Fold Belt System, northeast Queensland, Australia

The Tasman Fold Belt System in eastern Australia provides a record of the Palaeozoic geological history and growth of the Australian continent along the proto-Pacific margin of Gondwana inboard of an extensive and long-lived subduction system. The Hodgkinson and Broken River provinces represent prominent geological elements of this system and together form the northern Tasman Fold Belt System. Integration of newly-obtained data with a time-space evaluation of the geological evolution of the Hodgkinson and Broken River provinces, as well as other terranes in the northern Tasman Fold Belt System, allows for the development of a geodynamic model for the Palaeozoic evolution of the northern Tasman Fold Belt System. Our model indicates that three cycles of extension ? contraction occurred during the Palaeozoic evolution of the northern Tasman Fold Belt System. Episodes of extension were controlled by roll-back of the subduction system along the Australian margin, whereas episodes of contraction resulted from accretion following the arrival of positively buoyant segments (i.e., micro-continental blocks / oceanic plateaux) at the subducting trench. Our composite interpretative model on the geodynamic evolution of the northern Tasman Fold Belt System integrates the timing of the development of mineral deposits throughout this part of the system and provides a significant advancement in the understanding of Palaeozoic geodynamics along the margin of Gondwana in northeast Australia.

Genesis of orogenic-gold deposits in the Broken River Province, northeast Queensland

We report results of metallogenic, structural, petrological, and fluid-inclusion studies that characterise the nature of gold mineralisation in the Amanda Bel Goldfield, the most significant gold producer in the Palaeozoic Broken River Province of northeastern Queensland, Australia. Gold–antimony–arsenic and gold–arsenic deposits in the Amanda Bel Goldfield occur along distinctive northeastern trends, suggesting a strong structural control for their development during several phases of deformation in the Devonian to Carboniferous. Field evidence, as well as petrographic, scanning electron microscope and fluid-inclusion analysis of mineralised samples, indicate the presence of two main stages of gold genesis. These are distinguished by the coarse grained versus invisible nature of gold particles and their association with particular sulfide phases. A third stage of gold deposition is attributed to introduction of antimony±gold-rich ore fluids. Fluid-inclusion studies record minimum trapping temperatures between 140 and 380°C, and salinities of up to 6.5 wt% NaCl equivalent for the two main gold-forming stages. Our analyses further indicate that mineralising solutions for the earlier of the two main gold-forming stages were slightly more saline, and that the ore-hosting veins formed at higher temperatures. The style of gold mineralisation in the Amanda Bel Goldfield is compatible with orogenic gold deposits that form primarily during compressional and transpressional deformation along convergent plate margins in accretionary and collisional orogens. The increased understanding gained from our studies on the origin and nature of the deposits aids predictive mineral discovery elsewhere in the Broken River Province, and also in analogous terranes throughout the Tasman Fold Belt System of eastern Australia.

A new Middle Devonian arthrodire (placoderm fish) from the Broken River area, Queensland

Associated bones of the trunk-armour belonging to a large brachythoracid arthrodire are described as Confractamnis johnjelli n.gen. and n.sp. The specimen comes from strata of probable Eifelian age in the Broken River Group of Queensland. It shows a range of derived brachythoracid features including reduction of dermal ornament, and strong development of the dermal neck joint articulation. The posterior dorsolateral and posterior lateral plates of the trunk armour were high and narrow, and the anterior lateral plate had a distinctive narrow bilobed dorsal angle as indicated by the shape of its overlap area on the anterior dorsolateral plate. A provisional reconstruction suggests that the bones came from a large fish over 2 m in length. A cross section of the trunk armour is compared with the large arthrodire Taemasosteus from the Early Devonian of Burrinjuck, New South Wales. A possible close relative of this new taxon has been illustrated from the Early Devonian of Morocco, supporting other indications of resemblance in placoderm fish assemblages between these regions of east and north Gondwana during the Early-Middle Devonian.

Spawning time and early life history of Murray cod, Maccullochella peelii (Mitchell) in an Australian river

I investigated aspects of the early life history of Murray cod in the Broken River, southern Murray-Darling Basin, Australia. I documented patterns in abundance, length, age and the amount of yolk of drifting free embryos and estimated spawning periods for adult Murray cod in two reaches throughout each breeding season between mid-October and mid-December from 1997 to 2001. Free embryos began drifting in late-October and continued until mid- to late-December. Abundances of drifting free embryos showed no obvious peak in most years and were unrelated to discharge. Length, amount of yolk and age typically varied with sampling date, but only age showed strong and negative correlations with temperature. Thus, it appears that temperature affected rates of development, and that developmental stage, not length or age, was likely to be the determinant for when free embryos left the paternal ‘nest’. Most free embryos were estimated to have spent between 5 and 7 days drifting. Spawning of Murray cod in the Broken River usually commenced in mid-October and continued until at least early December. Initiation of spawning was associated with temperatures of 15°C and above, but discharge was highly variable, and no other environmental variables were consistent across years. The mid-point of spawning – usually in the first week of November – is considered a more significant time, because it likely coincides with peak spawning, and conditions during and immediately after this time are expected to be optimal for the survival of eggs and free embryos.

Variability in benthic respiration in three southeastern Australian lowland rivers

Benthic respiration is an important measure of decomposition processes occurring in streams, but our understanding of benthic respiration in lowland rivers is not well developed, particularly the factors that affect benthic respiration. In our study we measured benthic respiration at three sites in three contrasting lowland rivers in southeastern Australia. On most sampling occasions, rates of oxygen consumption in benthic chambers were linear. However, oxygen consumption rates fitted exponential decay curves during periods of highest microbial activity. Benthic community respiration ranged from 289 to 619 mg O2 m2 d−1 in the Broken River, from 178 to 1438 mg O2 m2 d−1 in the River Murray and from 127 to 2178 mg O2 m2 d−1 in the Ovens River. Benthic respiration was closely correlated with water temperature, but not with sediment carbon content, sediment particle size, water column nutrients or water column dissolved organic carbon concentrations. Average carbon turnover periods were between 1.7 and 6 years for the three rivers, but were as low as 0.1 year immediately following an event that gave rise to mobilization of in-stream dissolved organic carbon, sufficient to produce coloured water. The latter occurred in the Ovens River as a consequence of a rain event during a period of base-flow. Flow regime as such did not have a major impact on benthic community respiration. Induced changes in respiration, by altering flows, would only occur by altering the quality and timing of carbon inputs, since temperature and carbon quality, rather than quantity, appear more important in determining lowland river benthic respiration. Copyright © 2005 John Wiley & Sons, Ltd.

Is the home range concept compatible with the movements of two species of lowland river fish?

Summary Many studies of the movements of riverine fish have found that most individuals are sedentary and occupy very restricted home ranges. Recently, this ‘Restricted Movement Paradigm’ has been challenged and there is currently a need for tests of the home range concept as a theoretical basis for describing the movements of riverine fish. In this paper, I describe a radio‐tracking study of golden perch (Macquaria ambigua) and carp (Cyprinus carpio) in the Broken River, Australia that aims to assess the home range concept as a means of describing the movements of these species. A random movement analysis and a translocation experiment were conducted to test for site fidelity and home range occupation. Both golden perch and carp exhibited strong site fidelity and occupied restricted home ranges. Carp had larger total home ranges than golden perch, and both species had areas of concentrated use (core areas) within the home range. Several golden perch and carp exhibited shifts in the locations of their home ranges during the study. To incorporate such shifts into a theoretical framework, a ‘home range shift’ conceptual model is proposed and the need to consider the temporal stability of site fidelity when describing home range movements is discussed.

Low‐grade metamorphism in the Palaeozoic sequences of the Townsville hinterland, northeastern Australia

The transition from diagenesis to low‐grade metamorphism for the Ordovician ‐ Early Carboniferous sequences of the Burdekin and Clarke River Basins and the Broken River ‐ Camel Creek region is characterised by b ‐cell dimension and Kübler Index (KI = illite crystallinity) of K‐white micas, clay‐mineral assemblages and conodont colour alteration index (CAI). Data indicate that: (i) there is a regional metamorphic pattern characterised by anchizonal conditions, with consistently higher grade in the Camel Creek region (or Subprovince); (ii) anomalies are explicable in terms of location relative to areas of differing intensity of deformation (e.g. the Ruxton Formation) and inferred greater depth of burial (e.g. southern versus northern outcrop tracts of Quinton Formation); (iii) the regional pattern in the Broken River ‐ Gray Creek area shows general alignment with the regional grain; (iv) there is a generalised north to south increase in CAI for the Broken River region (‘Top Hut’ to Broken River, 6), with higher values towards the Montgomery Range intrusions; (v) in the Burdekin Basin, there arehigher CAI values north of Mt Podge and ‘Star’, and lower values (

A demonstration of the flow events method: environmental flow requirements of the Broken River

The Flow Events Method is a procedure for (i) assessing the ecological impact of flow regulation, (ii) developing environmental flow rules and (iii) optimising the operation of a water resource scheme to maximise environmental performance. The method is a systematic, transparent and defensible tool for use in environmental flows studies that makes use of available knowledge and facilitates the inclusion of expert opinion where necessary. It is not presented as a new technique, rather it is a logical and transparent procedure for integrating the concepts and data commonly used in environmental flow studies in Australia. The primary component of the method is the assessment of flow regulation based on changes in flow events that are considered to be important for specific ecological processes. This paper describes the application of the Flow Events Method to assess the impact of flow regulation in the Broken River catchment, including data and modelling requirements for this study. Six aspects of the flow regime are considered: (i) rapid increases in flows, (ii) rapid reduction in flows, (iii) the availability of slow water habitats, (iv) drying of the streambed, (v) the availability of shallow water habitats and (vi) inundation of channel benches.

Age constraints on deformation of the eastern Hodgkinson Province, north Queensland: New perspectives on the evolution of the northern Tasman Orogenic Zone

Granitic plutons of the Wangetti and Mt Formartine Supersuites intrude the Hodgkinson Formation of the Macalister Range district of the eastern Hodgkinson Province, north Queensland, Australia. Field and microstructural analyses of country‐rock fabrics and those of the granites show four deformational events (D1–D4) for the district, in common with other sectors of the Hodgkinson Province. Structural relationships show that plutons of the two supersuites were emplaced at different times. The Wangetti Granite lacks fabric development, but the deflection of country‐rock cleavage trends around it and the microscale crenulation of S2 on the rims of D4 porphyroblasts within its aureole indicate syn‐D4 emplacement, consistent with the Early Permian crystallisation age attributed to this pluton from isotopic evidence. Plutons of the Mt Formartine Supersuite show the effects of multiple (D2–D4) deformation. An emplacement age of 357 ± 6 Ma (latest Devonian) was obtained for this granite by SHRIMP U–Pb analyses of zircon. This identifies an early episode of plutonism for the Hodgkinson Province, most granites from which are of Permian age. The new date constrains the age of D2 for the Macalister Range district and the age of the protolith of the Hodgkinson Formation as pre‐Carboniferous. It matches the age previously determined for one of several small, related granitic stocks in the southeastern Camel Creek Subprovince of the Broken River Province. Structural relationships for granites of this age suggest that their emplacement was broadly associated with the first episode of regional‐scale orogenesis and the development of penetrative fabrics in the Hodgkinson — Broken River Fold Belt.

Devonian placoderm scales from Australia

ABSTRACT The morphology and histology of Australian placoderm scales which were found associated with dermal plates are described and compared. The specimens include the arthrodire Buchanosteus confertituberculatus from the Early Devonian (Emsian) of Buchan, Victoria, the arthrodires Goodradigbeeon australianium and Buchanosteidae gen. et sp. indet., the acanthothoracid Murrindalaspis wallacei from the Emsian of Taemas, New South Wales, and the antiarch Wurungulepis denisoni from the Emsian of the Broken River Group of northern Queensland. Isolated scales from Emsian limestones of Taemas-Wee Jasper, N.S.W., and Tyers, Victoria, and Lochkovian/Pragian assemblages from New South Wales and Queensland are also reviewed, to indicate the potential biostratigraphical value of placoderm scales in microvertebrate faunal assemblages, and their relevance to phylogenetic analysis.

Silurian and Devonian clathrodictyids and other stromatoporoids from the Broken River region, north Queensland

Stromatoporoids are well represented in the carbonate depositional phases of the Middle-Upper Silurian Jack Formation, the Lower-Middle Devonian Shield Creek Formation and Broken River Group of north Queensland. A total of 4 species of Labechiida, 4 species of Actinostromida, 14 species (4 new) of Clathrodictyida and 5 species (1 new) of Stromatoporellida are described and illustrated. They include the new species Gerronostroma doseyense, G.? apertum, Schistodictyon jackense, Atelodictyon repandum and Hermatostroma malletti. The fauna comprises representatives of Cystostroma, Labechiella, Stylostroma, Actinostroma, Aculatostroma, Ecclimadictyon, Plexodictyon, Anostylostroma?, Nexililamina, Pseudoactinodictyon, Tienodictyon, Simplexodictyon, Stromatopororella, Stictostroma, Trupetostroma?, Amnestostroma and Stachyodes. Included are revisions of a number of C.W. Mallett's species first described in the early 1970s. The genus Nexililamina Mallett is reinterpreted as a clathrodictyid. The history of the ‘less advanced’ labechiids suggests they came close to extinction in the Early Devonian. However, they survived as a distinctive, relict stock in the Lower Devonian Broken River assemblages (up to 4 genera recorded), and lived in close association with non-labechiid components of the fauna.