Complex Burrows Research Articles

Exceptionally preserved burrows of ichnogenus Asterosoma from the lower Silurian of South China: systematic ichnology, palaeoecology and implications for ecosystem recovery following the late Ordovician mass extinction

Exceptionally preserved complex burrows are described from the lower Silurian of South China, and they are identified as Asterosoma ludwigae Schlirf, 2000, which is characterized by the straight or curved bulbs that bud from an axial, vertical or horizontal, cylindrical burrow following a dichotomous or fan-like pattern. Striae and concentric lamination of burrow fills indicate that the special mining behaviour of the tracemaker reflects appendages that imprinted the burrow wall during their activities, speculating that polychaetes or holothuroides could be strong candidates of the tracemaker of A . ludwigae . Abundant organic-matter-rich peloids and muddy matrix in burrow fills may consist of tracemaker's secretions or excrement. Abundant extracellular polymeric substance (EPS) and clay minerals in filling sediment indicate the possible presence of microbes, implying that Asterosoma is not a simple fodinichnion, but rather created a beneficial symbiosis between tracemakers and microbes in burrows. Phanerozoic spatiotemporal distributions indicate that Asterosoma was distributed in broad habitats from deep sea to delta, but showed a strong preference for the shallow sea. Compilation of new ichnofossils and previously reported ichnotaxa from South China reveals that ichnospecies richness, burrow size and complexity all increased significantly during the late Aeronian, indicating a full recovery after the late Ordovician mass extinction.

On a new, burrow-associated species of Salmoneus Holthuis, 1955 (Decapoda: Alpheidae) from the Indo-West Pacific

A new alpheid shrimp, Salmoneus ngae sp. nov., is described based on two specimens collected on a near-shore, seagrass-rubble sandflat on the north-eastern coast of New Caledonia. The material from Lombok, Indonesia, previously reported as S. alpheophilus Anker & Marin, 2006, is reidentified as S. ngae sp. nov. The new species is a member of the informal S. gracilipes Miya, 1972 species group and appears to be a symbiont of spacious and complex burrows of the snapping shrimp Alpheus rapax Fabricius, 1798. Thus, S. ngae sp. nov. joins an ecological guild within the genus Salmoneus, which is composed of seven species associated with burrows of Alpheus spp. in various parts of the world and in different habitats.

Analysis of bone structure in PEROMYSCUS: Effects of burrowing behavior.

We compare the effects of burrowing behavior on appendicular bone structure in two Peromyscus (deer mouse) species. P. polionotus creates complex burrows in their territories, while P. eremicus is a non-burrowing nesting mouse. We examined museum specimens' bones of wild-caught mice of the two species and lab-reared P. polionotus not given the opportunity to burrow. Bones were scanned using micro-computed tomography, and cortical and trabecular bone structural properties were quantified. Wild P. polionotus mice had a larger moment of area in the ulnar and tibial cortical bone compared with their lab-reared counterparts, suggesting developmental adaptation to bending resistance. Wild P. polionotus had a larger normalized second moment of area and cross-sectional area in the tibia compared with P. eremicus. Tibial trabecular analysis showed lower trabecular thickness and spacing in wild P. polionotus than in P. eremicus and femoral analysis showed wild P. polionotus had lower thickness than P. eremicus and lower spacing than lab-reared P. polionotus, suggesting adaptation to high loads from digging. Results lay the groundwork for future exploration of the ontogenetic and evolutionary basis of mechanoadaptation in Peromyscus.

Influence of Temporal Variation on Morphology and Architecture in Burrows of Ocypode Rotundata (Miers, 1882) on Salakh Beach of Qeshm Island, the Persian Gulf

Variability over time in morphology and architecture of burrows excavated by Ocypode rotundata was studied on Salakh beach, Qeshm Island, Persian Gulf. According to our results, O. rotundata excavated single Shafts, J-shaped, Y-shaped, spiral and complex burrows, with spiral and complex burrows occurring only in adult crabs. The results showed that mating and reproduction behaviour of O. rotundata mainly occurred in the upper foreshore zone. Based on carapace width data and sex, percentage of J-shaped and Y-shaped burrow were more in female young crabs compared to males. Whilst, percentage of constructed single Shaft, J-shaped burrows were more frequent in male adult crabs compared to females. On the other hand, created complex burrow was observed just in male adult crabs. Also, male crabs created sand pyramid mounds seaward in front of the burrows. Four types of sand disposal behaviour were observed: knocking, throwing, slamming (only males) and stacking (only males). Results indicated that O. rotundata constructed burrows with any shape in all types of sediment, from the backshore to the foreshore. Sand moisture decreased with distance from the sea, which was associated with an increase in burrow depth. Temporal variation had significant impact on burrow slope, so that the entrance branch of all burrow shapes was clearly steeper during the reproduction period in contrast to the same burrows created in the non-reproduction period.

Crab Species-Specific Excavation and Architecture of Burrows in Restored Mangrove Habitat

Burrowing crabs are considered to be ecosystem engineers, playing a vital role in mangrove ecosystems through bio-geochemical transformation. This process depends on the size and shape of burrows. The present study analyzes the architecture of burrows constructed by crabs in a restored mangrove habitat. Fourteen crab species were found to construct burrows of 13 different shapes, with a predominance of I-, J-, and L-shapes. Sesarmids were larger in size than fiddlers, and made burrows with wider openings mostly in the Rhizophora zone. Fiddlers constructed complex burrows with a vertical position, and made longer and deeper burrows in contrast to sesarmids, which formed simple burrows with a horizontal position, digging shorter and shallower burrows in Avicennia or open zones. The sesarmids had smaller burrows without branching in mangrove zones, whereas the fiddlers had larger burrows with or without branching in open and Avicennia zones. The burrows of fiddler crabs, especially Austruca occidentalis and A. annulipes, had separate openings and passages for exit and entry as an adaptation against predators. The present work identified Austruca occidentalis and A. annulipes as the most potent bioturbating crab species in restored mangrove habitats due to their efficiency in soil excavation and formation of large-sized burrows.

Conservation and Taxonomic Assessment of an Undescribed Crayfish in Coastal Virginia

Creaserinus fodiens (Cottle 1863), commonly known as the digger crayfish, is a primary burrower that inhabits complex burrows in wetlands, seasonal pools, wooded floodplains, and roadside ditches. Historically, C. fodiens have been found from Ontario, Canada following the United States down to Texas and across four Atlantic slope states including Virginia, Maryland, North Carolina, and South Carolina. The Atlantic slope clades are geographically isolated from other C. fodiens populations by the continental shelf on the East coast and by the Blue Ridge Mountains. Despite having a wide geographical range, little research has been done on the Atlantic slope clades of Creaserinus spp. Recent genetic and morphological data suggests that the Virginia population of C. fodiens could be described as a different species. Additional morphological and genetic data from gill samples will lead to a better understanding of where the separation in classification lies among the Virginia population. A conservation and taxonomic assessment for Creaserinus fodiens along the Virginia Atlantic slope will be constructed from the results. These assessments will contribute to our understanding of global crayfish biodiversity and provide important biological insight to the management and conservation of these species.

Simple and complex burrow morphology in two Macrophthalmus species on the intertidal mudflats of Barr Al Hikman, Sultanate of Oman

ABSTRACT Burrowing Ocypodoidea crabs are an abundant component of many tropical and temperate coastal areas and central to the ecosystem functioning, for instance because they recycle nutrients, are important food for many shorebirds and alter the sediment through their burrowing behaviour. The burrow morphology of these crabs may differ between and within species, often correlated with differences in habitat preferences, crab morphology and life-history traits. Here we studied the burrow morphology and complexity of Macrophthalmus sulcatus and Macrophthalmus depressus, by means of casts (n = 7 and 10, respectively) and burrow excavations (n = 17 and 16, respectively) at the pristine intertidal mudflats of Barr Al Hikman in the Sultanate of Oman. We found that M. sulcatus construct simple burrows that were in all but one case inhabited by a single crab. By contrast, all burrows of M. depressus were complex, with multiple entrances and many (deep-reaching) branches. There was a strong relationship between M. sulcatus carapace width and burrow entrance size, indicating that the simple burrows are adapted to and made by the occupant. There was no relation between M. depressus carapace width and burrow entrance size, and in six burrows more than one crab was encountered, suggesting that the complex burrows are not made by and adapted to a single occupant. The complex burrows were found close to the shore whereas the simple burrows were found at the intermediate tidal zone. We speculate that the striking differences in burrow morphology may be explained by difference in habitat selection of the studied crabs, which most importantly relates to differences in sediment structure and tidal height. Crab morphology and life-history traits of the studied crabs could also account for the observed difference in burrow morphology.

Burrow utilization by the Japanese mitten crab <i>Eriocheir japonica</i> in the clay sediment of a freshwater river of Kyushu, Japan

This is the first record of the burrows of the Japanese mitten crab Eriocheir japonica. Morphologies of the burrows found in the clay sediment used by this crab were recorded by excavating them in a small freshwater river in Japan. Only E. japonica was found inside 2 of the 10 burrows examined (15 crabs and one crab, respectively), and the other 8 were empty. Crabs of various sizes (6.1–47.0 mm in carapace width) were collected from inside the occupied burrows. Burrow morphology ranged from single tunnels to complex burrows with multiple openings and tunnels. Openings (2–10 cm in diameter) were mostly located underwater. The single tunnels were 14–65 cm long. Considering the different digging habits of other burrowing animals found in this area, it can be concluded that E. japonica constructed these burrows. Burrows resembled those of the Chinese mitten crab E. sinensis, but were different in their location (freshwater vs. tidal), sediment type (clay vs. sand and silt), opening placement (mainly underwater vs. intertidal) and occupation rate (low vs. high). The low occupation rate suggests that E. japonica do not always rest in their burrows and rather prefer to hide beneath the riverbed’s large rocks. These results reflect the adaptation of E. japonica to the unstable environment of Japanese rivers.

Burrow Morphology of Brachyuran Crab Dotilla blanfordi Alcock, 1900 from Gulf of Khambhat, Gujarat, India

The present study was conducted to understand the burrow morphology of brachyuran crab Dotilla blanfordi Alcock, 1900 at Dandi beach located in Gulf of Khambhat of Gujarat state, India. Burrows were selected randomly and their opening diameter was recorded. Diluted resin was poured in the burrows to generate burrow cast. If the occupant crab emerges out of the burrow, it was captured and carapace width and gender was recorded. The shapes of complete burrow casts were identified and measurements of various morphological characters of burrow cast were recorded. Total 7 different burrow shapes were identified, out of which single tube burrow was the most common as compared to other burrow shapes. The crab carapace width showed significant relationship with burrow opening diameter, burrow depth, burrow length and burrow volume. Juveniles (3.45 mm CW) were making burrow of all the seven shapes. Burrow depth, length and volume were significantly higher in adult crabs as compared to juveniles. No significant variation was observed between burrows of male and female individuals. The present study showed that burrow morphology is highly affected by the crab body size and also varies significantly with different life stages of the crab. Juveniles make shallow and simple burrows as their smaller gill areas stores lesser amount of respiratory water which needs to be changed frequently. However, adults make complex burrows to perform various tasks including copulation and reproduction.

Effect of Anthropogenic Pressure on Distribution and Burrow Morphology of the Brachyuran Crab, Dotilla blanfordi Alcock, 1900 (Decapoda: Brachyura) Inhabiting Mudflats of North Western India

Coastal regions are one of the most crucial ecosystems as they support biology of numerous vertebrate and invertebrate taxa which provide economic aid to mankind. Monitoring of the natural resources of the coasts and to test the ecological impact of human disturbance therefore becomes necessary. The present study was conducted from 26th January to 18th February 2019 to investigate the effect of anthropogenic impacts on the population (burrow density, distribution and size) and burrow characteristics (burrow length, depth, inclination angle, weight and volume) of Dotilla blanfordi Alcock, 1900. Total eight sandy beaches of Gujarat and Maharashtra states of India were examined. The beaches were categorised into pristine, moderately impacted or heavily impacted sites on the basis of various levels of anthropogenic pressures. It was found that the burrow density was observed maximum at the low impacted sites (Tithal --21.11±13.53; Dandi site-2 --20.66±11.23), as compared to the moderately impacted sites (Umargam-- 16.11±21.62; Gorai-- 20±10.77; Uran-- 7.11±10.99) and heavily impacted sites (Kuda-- 5.11±14.24; Koliyak-- 1.56±2.01; Dandi site 1-- 11.78±8.27). The crabs built simple burrows in heavily impacted sites as compared to the complex burrows in the moderately affected and pristine sites. Burrow weight and burrow volume showed significant variation across all study sites as compared to other morphological traits. The results inferred that anthropogenic stress can directly influence the distribution and burrow morphology of Dotilla blanfordi. The results also suggested utility of D. blanfordi as an indicator species for effective coastal management but the outcomes would benefit with a comprehensive study of environmental as well as ecological characters.

Fine-Scale Spatial Structure of Soil Microbial Communities in Burrows of a Keystone Rodent Following Mass Mortality

Soil microbial communities both reflect and influence biotic and abiotic processes occurring at or near the soil surface. Ecosystem engineers that physically alter the soil surface, such as burrowing ground squirrels, are expected to influence the distribution of soil microbial communities. Black-tailed prairie dogs (Cynomys ludovicianus) construct complex burrows in which activities such as nesting, defecating, and dying are partitioned spatially into different chambers. Prairie dogs also experience large-scale die-offs due to sylvatic plague, caused by the bacterium Yersinia pestis, which lead to mass mortality events with potential repercussions on microbial communities. We used 16S sequencing to examine microbial communities in soil that was excavated by prairie dogs from different burrow locations, and surface soil that was used in the construction of burrow entrances, in populations that experienced plague die-offs. Following the QIIME2 pipeline, we assessed microbial diversity at several taxonomic levels among burrow regions. To do so, we computed community similarity metrics (Bray–Curtis, Jaccard, and weighted and unweighted UniFrac) among samples and community diversity indexes (Shannon and Faith phylogenetic diversity indexes) within each sample. Microbial communities differed across burrow regions, and several taxa exhibited spatial variation in relative abundance. Microbial ecological diversity (Shannon index) was highest in soil recently excavated from within burrows and soils associated with dead animals, and was lowest in soils associated with scat. Phylogenetic diversity varied only marginally within burrows, but the trends paralleled those for Shannon diversity. Yersinia was detected in four samples from one colony, marking the first time the genus has been sampled from soil on prairie dog colonies. The presence of Yersinia was a significant predictor of five bacterial families and eight microbial genera, most of which were rare taxa found in higher abundance in the presence of Yersinia, and one of which, Dictyostelium, has been proposed as an enzootic reservoir of Y. pestis. This study demonstrates that mammalian modifications to soil structure by physical alterations and by mass mortality can influence the distribution and diversity of microbial communities.

Structural characteristics of crab burrows in Hong Kong mangrove forests and their role in ecosystem engineering

Crab burrowing activity impacts several important biogeochemical processes within mangrove forests. Burrow morphology has been shown to be variable between brachyuran families, hence the community structure and composition of burrowing crabs may have the potential to impact ecosystems differently. By increasing belowground surface area, volume and bacterial microhabitats, large and complex burrows may differ from smaller and simpler burrows in their impact to nutrient and organic matter distribution. The central aim of this work was to provide a detailed quantification of the scale to which different mangrove crab families impact Hong Kong mangrove ecosystem through their burrowing activities. To achieve this goal, we recorded burrow densities and described specie-specific burrow morphology, through casts and 3D scans, of eight crab species belonging to four families, across three mangrove forests. Where present, the large and complex burrows of Parasesarma bidens (Sesarmidae) increased the total below ground air-sediment surface area per m2 by ~190% and accounted for ~1.9% of excavated volume per m3 of mangrove sediment. On average, the burrows of Metaplax spp. (Varunidae) increased the surface area by ~55%, while the ocypodid and dotillid species accounted for a 10–25% increase across sites. Due to its densities and the complexity of its burrows, P. bidens showed to exert a wide impact on Hong Kong mangrove ecosystems unrivalled by other species. By incorporating species-specific burrow characteristics and actual burrow densities, we were able to accurately estimate the differential bioengineering role of the dominant mangrove crab species. Due to the functional role of crab bioengineering, our estimates are critical to assess Hong Kong mangrove ecosystem functioning and health.

Analysis of the Form-Function Relationship: Digging Behavior as a Case Study

Studies of functional morphology focus on species showing evident specializations, or at least some degree of divergence from the so-called “generalized phenotype.” This may have led to the proposal of the form-function correlation paradigm, which assumes that there is a close relationship between anatomical traits and their biological use. A question that arises in relation to digging is what minimum structural and functional requirements would be needed to carry it out properly regarding a particular biological role? Here, we review the main approaches and results achieved in the study of morphological traits related to the highly mechanically demanding function of digging, especially in the South American subterranean rodents Ctenomys and related caviomorph rodents within the mammalian context. It is seen that whatever the biological role that soil digging will play for a particular group of organisms, they must have the ability to disaggregate a relatively resistant material and, therefore, the magnitude of the produced force is a critical point. Muscles of diggers should not only be able to produce large forces but also to sustain them for long periods of time, for which the muscle architecture is another important issue. Digging tools (e.g., limb bones, claws, incisors, skull) must have the capacity to withstand the concomitant reaction forces without structural failure. In this regard cranial sutures, jaw and skull geometry could play an important role in force dissipation. Examples of species that do not diverge from the generalized surface-dweller phenotype, but are nonetheless capable of constructing complex burrows, are examined regarding some evolutionary scenarios where fulfilling minimum functional requirements would have allowed organisms to adequately perform new biological roles.

The trace fossil Thalassinoides bacae in the Cambrian Zhangxia Formation (Miaolingian Series) of North China

Branched, complex burrows with thick linings assigned to Thalassinoides bacae are abundant in the Cambrian Zhangxia Formation (Miaolingian Series) in southern North China. These burrows occur in thinly layered micritic limestones, which were formed in a restricted marine environment surrounded by oolitic shoals. The macromorphological characteristics of the burrows observed in outcrop, combined with microscopic burrow characteristics assessed using light microscopy and scanning electron microscopy, were used to analyze the ethology of T. bacae. The complex geometric characters of horizontal branching tubes and subvertical shafts reflect T.bacae is an agrichnical burrow system. The horizontal tubes were used to cultivate microbes for food, while the subvertical shafts provided openings to the sea floor. Organic material, iron minerals and pyrite framboids just present in the margin of the fill indicate a special micro-environment in the burrow system with a reducing environment and a high organic content, and they may provide evidence for microbial garden. The functions of the thick micrite lining may have included maintenancce of environmental conditions within the burrow and provision of suitable conditions for growing microbes. Dark-colored irregular areas around the lining are identified as diagenetic halos. The burrowers of T.bacae built complex burrows system and thick lining for cultivating microbes to survive in a restricted marine environment that was oxygen-poor and with low food availability, reflecting adaptive behavioral evolution of the metazoan in the middle Cambrian.

Ichnological analysis of Jurassic shallow to marginal marine deposits: example from Wagad Highland, Western India

Jurassic deposits of shallow to marginal marine (delta) environments are widely reported from different continents of the world. This study shows inter-relationship of the animal-sediment behaviours in shallow and marginal marine conditions, suggesting an interpretation of the possible ichnodisparity. The Jurassic succession exposed at Washtawa Dome and Adhoi Anticline of Wagad highland, Kachchh comprises an approximately 341 m thick succession, divided into two formations – Lower Washtawa and Upper Wagad Sandstone. Eight sparsely to highly bioturbated sedimentary units show twenty-three identifiable ichnospecies from fifteen ichnogenera representing five ichnoassemblages broadly attributable to the Skolithos and the Cruziana ichnofacies, and developed in shallow-marine strandplain shoreface and delta depositional facies. The relative frequency statistical data reveals the dominant occurrence of feeding structures generated by polychaetes preferentially in quartz arenites. These structures represent sub-horizontal, sub-vertical and complex burrows, and show twelve and six categories of architectural designing Callovian-Oxfordian of shallow-marine shoreface and Oxfordian-Kimmeridgian shallow-water delta successions, respectively. The lower ichnodiversity and ichnodisparity associated with the Oxfordian-Kimmeridgian deltaic intervals represents a decrease in the exploitation of under-used ecospace, due to unfavourable environmental conditions rather than an expression of evolutionary radiation.

Architecture Characteristics of Burrow System of Plateau Pika, Ochotona curzoniae

Burrows serve many functions for animals by providing a place for rearing young, sleeping, hibernation, food storage, protection from predators and extreme environment, and the function of burrows varies with the degree of burrow complexity. We studied the burrow architecture (length, internal dimensions, fractal dimension of tunnel systems, number of nesting chambers and surface holes) by excavating the tunnels of 24 burrow systems of the plateau pika (Ochotona curzoniae). Pikas have two types of burrow systems, namely temporary and permanent burrows. The number of surface holes and length of tunnels were significantly different between the temporary and permanent burrows. Tunnel width and tunnel height were not significantly different between the temporary and permanent burrows. The permanent burrow had a nesting chamber but temporary did not have any. No hoarding chamber was found in either the permanent or the temporary burrow. The temporary burrow was used to avoid predators in emergency situations, and probably was the initial stage of construction of more complex burrows of some dispersing pikas. Permanent burrows were used for avoiding predators, resting and rearing offsprings.

The Stellate Burrow: A Large and Complex Trace Fossil in Holocene Carbonate Eolianites of the Bahamas

abstractLarge, complex burrows, informally referred to as stellate burrows, are present in eolianites of windward sea-cliff exposures facing Exuma Sound on Moriah Harbour Cay (Exumas, Bahamas). These cliffs consist of limestones (age <1,800 years before present) assigned to the Hanna Bay Member of the Rice Bay Formation and comprise three progradational lithofacies of foreshore, backshore, and dune deposits. Upper foreshore and backshore beds contain well-preserved specimens of Psilonichnus upsilon, fossil burrows of the ghost crab Ocypode quadrata. The overlying eolianites exhibit typical physical sedimentary structures characteristic of coastal dunes, with the most striking feature being the abundant presence of stellate burrows consisting of a central shaft (∼3 to 7 cm diameter) and numerous upward-directed branches (∼1 cm diameter) with smooth, unlined walls that form a radiate pattern in cross section. Parallel central shafts commonly join at the base, forming distinctive U-shaped structures that reach total heights of >1 m. Other examples exhibit an irregular arrangement of shafts that merge to form exceptionally large and architecturally complex structures. The result is a distinctive ichnofabric reaching levels of 3 or more on the Droser-Bottjer Ichnofabric Index scale. The presence of abundant stellate burrows can result in a significant increase in porosity and permeability within host eolianites. Previously, stellate burrows were assigned to the ichnogenus Cellicalichnus, with origin attributed to burrowing and brooding activity of halictid (sweat) bees, common today in the Bahamas. Nonetheless, diagnostic cell structures are not present, and there are other important differences between stellate burrows and the previously described ichnospecies of Cellicalichnus. Other tracemaker possibilities are considered and evaluated, but firm identification of the tracemaker for the stellate burrows remains to be resolved.

Ecology, longevity and naked mole-rats: confounding effects of sociality?

Ecology, longevity and naked mole-rats: confounding effects of sociality?

A study of burrow morphology in representative axiidean and gebiidean mud shrimps, from the Persian Gulf and Gulf of Oman, Iran

Mud shrimps (formerly Thalassinidea) are common burrow dwelling decapod crustaceans in the littoral zone of the Persian Gulf and Gulf of Oman. Their burrow morphology was investigated using foam casting methods. The present study shows that the burrow morphology in Upogebia carinicauda is not consistent and the recorded variations are based on habitat type and some physical characteristics of sediments. Adult burrow morphology in sandy-muddy substrate with shells, and boulder field habitats were Y-shaped and complex burrows of horizontal channels with turning chambers and vertical connections to internal passages or crevices of boulders, respectively. In burrows of U. carinicauda, some narrow passages, connected to the upper part of adult burrows in sandy-muddy habitats, belong to juveniles. Another species, Neocallichirus jousseaumei was found under boulders in sandy-muddy habitats of the Gulf of Oman and Qeshm Island, Persian Gulf. Since this type of habitat is special in some features, no conspicuous ex-current openings (usually obvious as conical mounds of extruded sediment) have been observed on the sediment surface; as these were hidden among the boulders surrounded by mixed sand and shells. The only method for observing this type of burrow was to remove the boulders by hand or lever.

Larval burrow morphology and groundwater dependence in a mire-dwelling dragonfly,Petalura gigantea(Odonata: Petaluridae)

Most species of petalurid dragonflies have a fossorial larval stage, which is unique in the Odonata. Larvae typically excavate burrows in soft peaty soils in mires, seepages or along stream margins, which are occupied by a single larva throughout the long larval stage. This paper reports on a study of burrow morphology in Petalura gigantea, with the objectives of describing their burrows, documenting any variability in burrow morphology across the hydrogeomorphic range of habitats used by the species, identifying factors contributing to any such variability, resolving questions in relation to the single previous illustration of a burrow system and identifying the level of groundwater dependence of larvae. The species was found to be an obligate, groundwater dependent, mire-dwelling species with well-maintained and sometimes complex burrows. Burrow complexity and morphological variation are inferred to be a response by larvae to the hydrogeomorphic characteristics of the habitat and substrate attributes. A...