Marine Benthos Research Articles

Bending fatigue strength of a steel, DistaloyAE : P. Beiss et al. (Aachen University of Technology, Aachen, Germany.)

A survey was carried out from April 1998 to June 2000 to study the structure of the population and the secondary production of Hediste diversicolor (Copenhagen 32 (1776) 274) in the Loire estuary, Atlantic coast of France. Each month, samples were collected in the intertidal zone of the Mindin harbour. In 1999, the mean annual density was 900±594 individuals (ind.) m−2 with a minimum of 304 ind. m−2 in February and a maximum of 2560 ind. m−2 in April. The mean annual biomass (dry weight) was B̄=9.1 g m−2 with a minimum of 1.2 g m−2 in January and a maximum of 26.0 g m−2 in July 1999. The density and the biomass of the population of H. diversicolor decreased during winter and increased during spring/summer. Size frequency histograms allowed the analysis of cohorts and gave the growth curves. Two recruitment periods were detected each year, in June/July and October. The secondary production was estimated by the method of Crisp (Methods for the study of marine benthos, Blackwell, Oxford, 1971). From June 1998 to May 1999, P=5.1gm−2 with B̄=4.6gm−2 and the ratio P/B̄=1.1 and from June 1999 to May 2000, P=34.4gm−2 with B̄=9.6gm−2 and P/B̄=3.6. The annual secondary production in 1999 was P=32.5gm−2 with B̄=9.1gm−2 and P/B̄=3.6. The differences observed between the 1986–1988 and 1998–2000 populations of H. diversicolor in the Loire estuary are discussed and could be explained by environmental changes, as competition or by migration of individuals.

Structure of the population and secondary production of Hediste diversicolor (O.F. Müller, 1776), (Polychaeta, Nereidae) in the Loire estuary, Atlantic Coast, France

A survey was carried out from April 1998 to June 2000 to study the structure of the population and the secondary production of Hediste diversicolor (Copenhagen 32 (1776) 274) in the Loire estuary, Atlantic coast of France. Each month, samples were collected in the intertidal zone of the Mindin harbour. In 1999, the mean annual density was 900±594 individuals (ind.) m −2 with a minimum of 304 ind. m −2 in February and a maximum of 2560 ind. m −2 in April. The mean annual biomass (dry weight) was B ̄ =9.1 g m −2 with a minimum of 1.2 g m −2 in January and a maximum of 26.0 g m −2 in July 1999. The density and the biomass of the population of H. diversicolor decreased during winter and increased during spring/summer. Size frequency histograms allowed the analysis of cohorts and gave the growth curves. Two recruitment periods were detected each year, in June/July and October. The secondary production was estimated by the method of Crisp (Methods for the study of marine benthos, Blackwell, Oxford, 1971). From June 1998 to May 1999, P=5.1 g m −2 with B ̄ =4.6 g m −2 and the ratio P/ B ̄ =1.1 and from June 1999 to May 2000, P=34.4 g m −2 with B ̄ =9.6 g m −2 and P/ B ̄ =3.6 . The annual secondary production in 1999 was P=32.5 g m −2 with B ̄ =9.1 g m −2 and P/ B ̄ =3.6 . The differences observed between the 1986–1988 and 1998–2000 populations of H. diversicolor in the Loire estuary are discussed and could be explained by environmental changes, as competition or by migration of individuals.

Diverse approaches to questions of Biodiversity: German contributions to studies of Marine Benthos around South America and Antartica

Una mirada al gradiente latitudinal desde America del Norte via Sur America hasta la Antartica sustenta la impresion que los ecosistemas de esta parte del mundo proveen condiciones perfectas para estudios de biodiversidad marina. Diversas iniciativas bilaterales e internacionales con mayores aportes alemanes se han concentrado en preguntas de biodiversidad especialmente en America del Sur y la Antartica. A profundidades >50 m accesibles a muestreos desde embarcaciones, una zona de minimo oxigeno (OMZ) predomina en Peru y Chile (excepto en el extremo sur) con una vida macrobentonica extremadamente pobre, mostrando un gradiente de incremento de diversidad a profundidades mayores y en sentido sur. En los fiordos y canales al sur de Chile la heterogeneidad del habitat parece ser muy alta y claras diferencias faunisticas pueden ser observadas a cortas distancias, especialmente en la region de Magallanes. Como consecuencia se puede esperar una alta biodiversidad entre-habitats (between-habitat). En la plataforma expuesta profunda alrededor de la Antartica un gradiente a gran escala entre una comunidad dominada por suspensivoros sesiles revelando biomasa y abundancia altas, puede ser distinguida de una comunidad con muy poca epifauna. Sin embargo, las relaciones con parametros ambientales son todavia vagamente entendidas. Para el futuro se recomiendan dos enfoques, estudiar preguntas zoogeograficas a la luz de la evolucion e identificar procesos clave que desplieguen patrones de biodiversidad incluyendo cambios ambientales.

Modification of Marine Benthos by Trawling: Toward a Generalization for the Deep Ocean?

Modification of Marine Benthos by Trawling: Toward a Generalization for the Deep Ocean?

Diversity, Biomass, and Ecosystem Processes in the Marine Benthos

Diversity, Biomass, and Ecosystem Processes in the Marine Benthos

A cross‐ecosystem comparison of the strength of trophic cascades

AbstractAlthough trophic cascades (indirect effects of predators on plants via herbivores) occur in a wide variety of food webs, the magnitudes of their effects are often quite variable. We compared the responses of herbivore and plant communities to predator manipulations in 102 field experiments in six different ecosystems: lentic (lake and pond), marine, and stream benthos, lentic and marine plankton, and terrestrial (grasslands and agricultural fields). Predator effects varied considerably among systems and were strongest in lentic and marine benthos and weakest in marine plankton and terrestrial food webs. Predator effects on herbivores were generally larger and more variable than on plants, suggesting that cascades often become attenuated at the plant–herbivore interface. Top‐down control of plant biomass was stronger in water than on land; however, the differences among the five aquatic food webs were as great as those between wet and dry systems.

ALLOGROMIIDS IN FORAMINIFERAL ASSEMBLAGES ON THE WESTERN EURASIAN ARCTIC SHELF

Allogromiids sensu lato , including the orders Allogromiida and Astrorhizida, are a commonly ignored group of marine benthos. Allogromiid standing crop was examined in 121 sediment samples from the Barents and Kara seas. In 44 of these samples, foraminiferal biomass was determined by calculation of cytoplasmic volume. Foraminiferal standing crop is dominated by small allogromiids in two types of stressed marginal environments—river-influenced shallows and glacially fed fjords. Allogromiid frequency also increases in oligotrophic depressions of the open shelf. Large astrorhizids such as Rhabdammina abyssorum, Pelosina variabilis and Hyperammina subnodosa , being common on fine-grained sediments which dominate the shelf, constitute biomasses of ca 3 mg/10cm 3 , exceeding by an order of magnitude the biomass of all other foraminifera combined. Foraminiferal biomass values are comparable to those of macrofauna in shelf depressions distant from land, thus suggesting that, at least in food-deficient areas, the allogromiid foraminifera are a key group in benthic energy flux.

Detrimental effects of sedimentation on marine benthos: what can be learned from natural processes and rates?

Benthic organisms are adapted to the natural processes of sediment movement, erosion and deposition. Laboratory studies have cataloged the range of responses to flow and sediment movement that allow benthos to survive, and even to thrive, under intense, storm-driven sediment movement. Extreme sedimentation events also result from man's modifications of the nearshore marine environment, and the scale and magnitude of these alterations can often greatly exceed that of natural occurrences. Unfortunately, there is little of the quantitative information necessary for predicting how materials placement, sediment deposition and erosion will affect the ecology of these environments. We are using both field and laboratory approaches in Delaware Bay to address two questions. First, what rates and frequencies of sediment movement characterize natural events, and second, what rates and frequencies are detrimental to representative benthic species and functional groups. We present these results as case studies that address ecological impacts of dredge materials placement, site selection and benthic community responses. Quantifying natural sedimentation rates and the susceptibility of macrofauna by functional groups are both critical to reliably predicting environmental impacts. If biological effects are parameterized appropriately (i.e. in terms of natural processes), it may be possible to employ the existing knowledge-base of benthic ecology to predict effects of disturbances and to design projects that will minimize these impacts. Materials placement that is analogous to natural events should allow community responses to follow natural seasonal and successional trends and to exhibit minimal anthropogenic impacts. When sedimentation exceeds natural thresholds, then impacts may involve total loss of the community and subsequent colonization by pioneer species. In this latter case, an entirely different suite of ecological processes will drive impacts and recovery, potentially leading to dramatically altered benthic communities. Understanding organisms’ sublethal responses and drawing on experimental ecological studies will lead to improved prediction of benthic community responses and more reliable assessment of project impacts.

Structure and Population Changes of the Marine Benthos during La Niña 1999-2001 in the Coastal Zone near Tumbes, Perú

Structure and Population Changes of the Marine Benthos during La Niña 1999-2001 in the Coastal Zone near Tumbes, Perú

Size‐dependent species‐area relationships in benthos: is the world more diverse for microbes?

Using original and literature data on species richness, I compared the species‐area relations for 5 different size classes of the Arctic benthos: macrofauna sensu lato, polychaetes, nematodes, ciliates and diatom algae. The data pool covered a wide range of areas from single samples to the whole seas. Both the slopes and intercepts of the curves depended significantly on the logarithm of the mean body size of the group. The number of small species (ciliates and diatom algae) showed relatively higher local diversity but increased more slowly with the area than the number of larger ones. Thus, both α‐ and β‐components of species diversity of the marine benthos were size‐dependent. As a consequence, the actual relations between number of species and their physical size are spatially scale‐dependent: there are many more species of smaller size classes in any one local community, but at a global scope the situation changes drastically. The possible reasons are discussed, including dispersal efficiency, rates of speciation and size‐dependent perception of environmental heterogeneity. Body size is suggested to be the important scaling factor in manifestation of so‐called “general ecological laws”.

Biogeomorphological implications of microscale interactions between sediment geotechnics and marine benthos: a review

Abstract At the foundations of biogeomorphological processes in the sea lie interactions between the activities of marine benthic animals and the geotechnical properties of their sedimentary environments. The potential significance of these interactions, which take place at a microscale level of millimetres to metres, for the large-scale geomorphology of the seabed has rarely been appreciated. In the context of this review, large-scale is defined as greater than 50 m to hundreds of kilometres. The present review addresses this link, drawing examples from a wide range of marine environments, including estuaries, the intertidal zone, continental shelves and slopes, and the deep sea. It firstly considers sediment stabilisation, slope failure, sediment mixing, biodeposition, sediment compaction, and hydrodynamic effects. This is followed by a consideration of two extremes of the ecological pyramid—the effects of marine meiofauna and marine vertebrates. The final section draws attention to the central role of faunal mucus and extracellular polymeric material (ECPM) in many of the microscale interactions that we describe. The implications of these microscale biological processes and features are discussed in terms of their influence on and control of the large-scale geomorphology of the seabed.

The Role of an Organic Slime Matrix in the Formation of Pyritized Burrow Trails and Pyrite Concretions

Abstract Sandstones from the Black Island member of the Winnipeg Formation (Ordovician) contain a variety of early diagenetic iron sulfide morphologies, including elongate concretions of variable length. Examination of sandstone samples with X-radiography reveals that these concretions, now consisting of pyrite, are associated with burrows. Detailed textural examination of the pyrite shows an anomalously loose packing of sand grains within these concretions, and also suggests that iron sulfide nucleation commenced at multiple sites in what must have been a stiff matrix. Compositional data acquired by electron microprobe indicate that the iron sulfides did not replace fecal matter left behind by the burrower. Sulfur isotope data point to bacterial sulfate reduction as a sulfide source, corroborated by fossilized bacterial remains within the concretionary pyrite. Mucus and slime trails of marine benthos were probably important for early diagenetic pyrite production in these sediments; they can be considered...

Re-evaluation of species diversity patterns of free-living marine nematodes

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 238:101-108 (2002) - doi:10.3354/meps238101 Re-evaluation of species diversity patterns of free-living marine nematodes V. Mokievsky1,*, A. Azovsky2 1P. P. Shirshov Institute of Oceanology RAS, Moscow, Russia 2Moscow State University, Faculty of Biology, Moscow, Russia *E-mail: vom@soil.msu.ru ABSTRACT: Nematode species diversity was analysed for 55 data points ranging from local studies to large-scale faunal surveys. Multiple regression analysis uses latitude, investigated area, sampling effort and depth as independent variables. Species diversity in a biotope (or α-diversity) is about twice as high in the deep sea, while the main source of diversity in shallow waters is heterogeneity of biotopes (β-diversity). For sites deeper than 100 m, regional species richness shows a unimodal (hump-shaped) latitudinal pattern, with the highest diversity at 30° to 60°N. Species diversity in shallow waters does not show any prominent gradients throughout the world ocean. These patterns possibly reflect the diversity-productivity relationships. Different approaches to estimation of species diversity are discussed. KEY WORDS: Species diversity · Latitudinal gradients · Marine benthos · Nematodes Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 238. Online publication date: August 08, 2002 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2002 Inter-Research.

Global Ordovician faunal transitions in the marine benthos: ultimate causes

During the Ordovician Radiation, domination of benthic marine communities shifted away from trilobites, toward articulated brachiopods, and, to a lesser degree, toward bivalves and gastropods. Here, models are formulated that mathematically represent alternative hypothesized causes of this transition. These include models in which per-genus origination or extinction probabilities were constrained to be (1) constant, (2) diversity-dependent, (3) productivity-dependent, or (4) jointly dependent on productivity and diversity. Using a method adapted from capture-mark-recapture (CMR) population studies, we estimate origination, extinction, and sampling probabilities jointly in order to avoid confounding patterns in turnover probabilities with temporal variation in the quality of the fossil record. Using Akaike's Information Criterion (AIC), we assessed the fit of the alternative causal models relative to one another, and relative to a noncausal “phenomenological” alternative that placed no constraints on the pattern of temporal variation in origination or extinction. There were differences among taxa in the relative fit of these models, suggesting that the effects of productivity and diversity varied among higher taxa. In the aggregate, however, there was strong support for diversity-dependent origination. For extinction, poor fit of the alternative causal models suggests that we lack a good explanation for extinction patterns. These analyses support the hypothesis that diversity-dependent origination, particularly in trilobites, contributed to the Ordovician faunal transitions. By contrast, the effects of increased productivity, if indeed they were large enough to influence global diversification patterns, did not proceed in the hypothesized manner.

DENSITY-DEPENDENT PREDATION, HABITAT VARIATION, AND THE PERSISTENCE OF MARINE BIVALVE PREY

The persistence of prey encountering intense predation varies by species, prey density, and habitat type; however, the collective impact of these factors has rarely been tested experimentally in natural marine systems. Using the thin-shelled clams Mya arenaria and Macoma balthica as prey, and the main epibenthic predator of whole adult clams, the blue crab Callinectes sapidus, we conducted a series of experiments in Chesapeake Bay tributaries that (1) links field abundance and distribution of bivalve prey species with habitat-specific mortality patterns; (2) represents the first comprehensive field test of species-specific, habitat-specific, and density-dependent mortality for subtidal, soft-bottom, deep-burrowing prey; and (3) thereby enables development of a conceptual model to be used as a heuristic tool linking predator–prey dynamics, habitat type, and evolutionary defense tactics for marine benthos. In 15 years of field monitoring, Mya was more common in sand than mud habitats, and Macoma was widely distributed and at higher densities than Mya in mud and sand. In field experiments, mortality of both Mya and Macoma was density dependent in those habitats where the clams are common. The blue crab population in the field exhibited a type III “guild functional response” on Mya in sand, and on Macoma in both mud and sand. Mortality was lower in sand than mud for Mya, and similar in mud and sand for Macoma, correlating with the high abundances of Mya in sand and Macoma in sand and mud. The persistence of large juvenile and adult bivalves when confronted with intense predation derived substantially from a low-density refuge from predation that varied in a species-specific manner with habitat type, demonstrating the species-specific importance of density and habitat to clam survival. We developed a conceptual model detailing the relative importance of behavior, morphology, habitat features, and the basic components of predator–prey interactions to the survival of bivalve molluscs. At one extreme are bivalve molluscs, such as oysters, that emphasize morphological refuges that increase the predator's handling time. At the other extreme are bivalves, such as Mya and Macoma, that reduce predator encounter rates. The model is intended to be used as a heuristic tool to develop testable hypotheses.

Do all mass extinctions represent an ecological crisis? Evidence from the Late Ordovician

The high rate of species extinction in recent decades is seen by many ecologists as heralding an extinction of catastrophic magnitude in the near future. The ecological consequences of such a biodiversity crisis are hard to predict, but some indication of likely effects can be gained from the knowledge of mass extinctions in the past. The Late Ordovician extinction was one of the five great extinctions in the geological record. It occurred in two phases about 0.5–1million years (Ma) apart and resulted from climatic and related environmental changes associated with the rapid growth and decay of the large Gondwanan ice cap. Overall, an estimated 86% of species became extinct, 61% of genera and 12–24% of families, but few or no orders or higher taxa. The extinction severely affected both marine benthos and plankton. Using brachiopod data as a measure of ecological change, it can be seen that the number of within-habitat species (alpha diversity) was severely reduced and the number and distinctness of benthic communities (beta diversity) on marine shelves also declined sharply. Concurrently the number of palaeogeographic provinces fell from ten to five, possibly as a result of a loss of endemic species and preferential survival of cosmopolitan species. At the peak of extinction, following the second extinction phase, the ecological structure of both benthic and planktonic ecosystems had been severely disrupted and downgraded in complexity as a wide variety of niches were ‘vacated’. In spite of the profound biodiversity and ecological crisis within this ‘survival’ interval, communities returned to their pre-extinction levels of alpha and beta diversity during the subsequent ‘recovery’ interval. In spite of the large amount of vacant ecospace to be filled there was very little innovation in terms of adaptive strategy, so that the structure of the emerging Silurian communities was similar to that of the Ordovician. In these terms the ecological recovery was remarkable, but it was also prolonged over about 4–5 Ma. On a geological time scale the biosphere returned to ‘normal’, but on a human time scale the mass extinction produced a very severely degraded biosphere. Copyright © 2001 John Wiley & Sons, Ltd.

Do all mass extinctions represent an ecological crisis? Evidence from the Late Ordovician

AbstractThe high rate of species extinction in recent decades is seen by many ecologists as heralding an extinction of catastrophic magnitude in the near future. The ecological consequences of such a biodiversity crisis are hard to predict, but some indication of likely effects can be gained from the knowledge of mass extinctions in the past. The Late Ordovician extinction was one of the five great extinctions in the geological record. It occurred in two phases about 0.5–1million years (Ma) apart and resulted from climatic and related environmental changes associated with the rapid growth and decay of the large Gondwanan ice cap. Overall, an estimated 86% of species became extinct, 61% of genera and 12–24% of families, but few or no orders or higher taxa. The extinction severely affected both marine benthos and plankton. Using brachiopod data as a measure of ecological change, it can be seen that the number of within‐habitat species (alpha diversity) was severely reduced and the number and distinctness of benthic communities (beta diversity) on marine shelves also declined sharply. Concurrently the number of palaeogeographic provinces fell from ten to five, possibly as a result of a loss of endemic species and preferential survival of cosmopolitan species. At the peak of extinction, following the second extinction phase, the ecological structure of both benthic and planktonic ecosystems had been severely disrupted and downgraded in complexity as a wide variety of niches were ‘vacated’. In spite of the profound biodiversity and ecological crisis within this ‘survival’ interval, communities returned to their pre‐extinction levels of alpha and beta diversity during the subsequent ‘recovery’ interval. In spite of the large amount of vacant ecospace to be filled there was very little innovation in terms of adaptive strategy, so that the structure of the emerging Silurian communities was similar to that of the Ordovician. In these terms the ecological recovery was remarkable, but it was also prolonged over about 4–5 Ma. On a geological time scale the biosphere returned to ‘normal’, but on a human time scale the mass extinction produced a very severely degraded biosphere. Copyright © 2001 John Wiley & Sons, Ltd.

Constraints on body‐size distributions: an experimental test of the habitat architecture hypothesis

Summary Holling (1992) has claimed that a range of mechanisms, including habitat architecture, may be responsible for discontinuities in body‐size distributions across a broad range of spatial and temporal scales. We tested this proposition in the marine benthos by manipulating habitat architecture directly. Specifically, we constructed artificial sediments (using glass beads) of uniform large or small particles, to change interstitial pore diameters at two estuarine sites. A combination of kernel estimation and smoothed bootstrap re‐sampling showed that there was a high and varaible degree of modality in body‐size (1–5 modes) in the experimental bead treatments and controls and no obvious evidence for a trough at organism size 0·5–1 mm ESD. We propose that habitat architecture may not be as intimately related to body‐size patterns as originally claimed, at least at smaller scales where experimental tests are tractable.

Global Ordovician faunal transitions in the marine benthos: proximate causes

During the Ordovician Radiation, domination of benthic marine communities shifted away from trilobites, toward articulate brachiopods, and, to a lesser degree, toward bivalves and gastropods. In this paper, we identify the patterns in origination and extinction probabilities that gave rise to these transitions. Using methods adapted from capture-mark-recapture (CMR) population studies, we estimate origination, extinction, and sampling probabilities jointly to avoid confounding patterns in turnover rates with temporal variation in the quality of the fossil record. Not surprisingly, higher extinction probabilities in trilobites relative to articulate brachiopods, bivalves, and gastropods were partly responsible for relative decreases in trilobite diversity. However, articulate brachiopods also had higher origination probabilities than trilobites, indicating that relative increases in articulate brachiopod diversity would have occurred even in the absence of between-class differences in extinction probabilities. This contrasts with inferences based on earlier Phanerozoic-scale, long-term averages of turnover probabilities, and it indicates that a major cause of this faunal transition has been overlooked.

A New Species of Mictognathus (Acari: Halacaridae) from the Great Barrier Reef

A New Species of Mictognathus (Acari: Halacaridae) from the Great Barrier Reef1 Jürgen C. Otto Abstract Mictognathus colemani Otto, n. sp., is described from the Great Barrier Reef. It is the third known species in its genus and the first species of Mictognathus known to occur in tropical waters. Distinguishing features are dorsal lamellae on the telofemora, membranous flaps on anterior and posterior dorsal plates, lack of distinct areolae or costae, relatively long median claws on all legs, and the lack of corneae. Some of these characters are similar to those of the mictognathine species Corallihalacarus chilcottensis, but it is unknown whether they indicate a close relationship. A key to species of Mictognathus is presented. Mites of the Family Halacaridae are common but minute (0.2-2 mm) inhabitants of the marine benthos and occur from the intertidal zone to the abyss. Approximately 1000 species have been described to date, but new species are added frequently, suggesting that many, perhaps most, of the world's halacarid species are still unknown. A genus only rarely encountered during halacarid surveys is Mictognathus Newell, of which two species were known previously, M. werthelloides Newell, 1984, and M. secundus Bartsch, 1992. In this paper I describe a third species of Mictognathus, which was found in coral sand in the southern section of Australia's Great Barrier Reef Marine Park. Materials And Methods The holotype specimen, deposited in the Queensland Museum (QM), at the branch Museum of Tropical Queensland in Townsville, was extracted from a hand-collected and subsequently frozen sediment sample. After thawing, the sample was vigorously stirred in a bowl of water and the supernatant decanted through a 100-mm sieve. The specimen was cleared in lactic acid and mounted in PVA. Measurements and the illustrations were obtained from the slide-mounted, slightly compressed specimen. Abbreviations in the description are as follows: AD, anterior dorsal plate; AE, anterior epimeral plate; GA, genitoanal plate; GO, genital opening; OC, ocular plate; pas, parambulacral seta(e); PD, posterior dorsal plate; P-1 to P-4, palp segments designated in sequence from the proximal to the distal; I-IV, leg I to leg IV. Additional abbreviations used in the illustrations are explained in their captions. Subfamily MICTOGNATHINAE Otto, 1999 Genus Mictognathus Newell, 1984 Mictognathus Newell, 1984:211; Bartsch, 1992:85 (type species: Mictognathus secundus Newell, 1984, by monotypy and original designation). Mictognathus colemani Otto, n. sp. Figures 1, 2 Type Material: Holotype: male, QMS105562, Great Barrier Reef, Turner Cay, NE, ca. 21° 43′S, 152° 330′E, 8 December 1998, G. Coleman coll., sand on reef flat. Etymology: Named in honor of Greg Coleman, who collected the only known specimen of this species. Diagnosis: Dorsal and ventral plates [End Page 43] overlapping, closely abutting or fused (Figure 1A, B). AE dorsally fused, forming a collar. Anal opening visible in ventral view. Five pairs of dorsal setae (excluding seta on PE). Gnathosomal base about as long as wide. Rostrum triangular, not connected to idiosoma via a flexible neck; both pairs of maxillary setae on rostrum. Palps four-segmented (Figure 1C), attached laterally; P-2 with one dorsal seta; P-3 with a minute median seta or seta absent; P-4 very slender, at least as long as P-2 and P-3 combined, with a single basal seta. Trochanters III and IV with dorsal triangular process or lamella. Tibiae I-IV with two bipectinate ventral setae. Telofemora I and II with large ventral lamellae. Telofemora, genua, and tibiae with elaborate articular lamellae. Tarsus I with three dorsal setae, one or two eupathid ventral setae, and a pair of doubled pas. Tarsus II with three dorsal setae, one ventral seta, and either a pair of doubled pas or a pair of pas singlets. Tarsi III and IV with three dorsal setae and a pair of pas singlets. Solenidion on tarsus I in dorsomedial position, that on tarsus II dorsolateral. All tarsi with two paired claws and median claw, all without pecten. Click for larger view View full resolution Figure 1. Mictognathus colemani, n. sp., male. A, Idiosoma, dorsal view; B, idiosoma and gnathosoma, ventral view; C, palp, dorsal view. AD, anterior dorsal plate; AE, anterior...