Christopher Mah

• PhD
• Research Collaborator at Smithsonian Institution

The methane seeps on the Pacific margin of Costa Rica support extensive animal diversity and offer insights into deep-sea biogeography. During five expeditions between 2009 and 2019, we conducted intensive faunal sampling via 63 submersible dives to 11 localities at depths of 300–3600 m. Based on these expeditions and published literature, we compi...

The North Pacific is a vast region, and undiscovered taxa from deep-sea habitats (>200 m), especially from below 1000 m continue to be described based on in situ and museum collections. The Goniasteridae is the most diverse of Asteroidea and further discoveries continue to be made. Here, one new genus and seven new species are described and novel o...

This paper reports several new occurrences for Asteroidea and Echinoidea in Hong Kong. New records for asteroids include Anseropoda rosacea, Aquilonastra cepheus, Pentaceraster alveolatus, Pentaceraster sibogae, and Culcita novaeguineae. For echinoids, new records include Coelopleurus maculatus, Eucidaris metularia, Prionocidaris baculosa, Echinost...

The methane seeps on the Pacific margin of Costa Rica support extensive animal diversity and offer insights into deep-sea biogeography and phylogeography. During five expeditions between 2009 and 2019, we conducted intensive faunal sampling via 63 submersible dives to 11 localities at depths of 300-3600 m. Based on these expeditions and published l...

Two new species and one new genus, collected by NOAA ship Okeanos Explorer, Bathyceramaster kelliottae n. sp. and Rhianastra isosceles n. gen., n. sp. (Goniasteridae; Asteroidea) are described from deep-sea settings in the North Atlantic. Two potentially undescribed species are observed from imagery and new in situ observations further elucidate li...

Sea stars are a major component of the megabenthos in most marine habitats, including those within the deep sea. Being radially symmetric, sea stars have sensory structures that are evenly distributed along the arms, with a compound eye located on each arm tip of most examined species. Surprisingly, eyes with a spatial resolution that rivals the hi...

Thirteen new records of Goniasteridae showing mesophotic occurrence are presented, including a new species of Pseudoceramaster doto n. sp. from southern Japan and a new genus and species, Churaumiastra hoshi nov. gen. nov. sp. which occurs in southern Japan, the Philippines and Western Australia.

Xyloplax is a genus of three species of sea stars previously found only on sunken wood in the deep ocean. Their circular and petaloid bodies, which lend them their common name “sea daisy”, and their presumed exclusive diet of wood make them an unusual and rare element of deep-sea ecosystems. We describe here the fourth species of Xyloplax from the...

Mah, C.L. 2023. A new species of Astrosarkus from Western Australia including new Mesophotic occurrences of Indian Ocean Oreasteridae (Valvatida, Asteroidea). Memoirs of Museum Victoria 82: 143–165. Astrosarkus lu n. sp. (Oreasteridae, Valvatida; Asteroidea) is described in addition to new in situ observations. Further occurrences of Indo-Pacific O...

The Poraniidae (Asteroidea, Valvatacea) is recorded for the first time from Australian waters at deep-sea (>200m) depths, including, at present, Australia’s deepest known asteroid occurrence from 3850 m. Three genera are reviewed, each represented by a single species, Poraniomorpha tartarus n. sp., Marginaster paucispinus Fisher 1913, and Marginast...

Assessment of Antarctic taxonomic diversity for asteroids and other taxa for poorly studied or unknown regions, such as the deep-sea, will be important for our understanding of these understudied habitats. Eleven new species and a new genus are described from three families (Asterinidae, Goniasteridae, Solasteridae) within the Valvatida, nearly all...

Background The growing interest in mineral resources of the deep sea, such as seafloor massive sulphide deposits, has led to an increasing number of exploration licences issued by the International Seabed Authority. In the Indian Ocean, four licence areas exist, resulting in an increasing number of new hydrothermal vent fields and the discovery of...

Recent expeditions to Rapa Nui (also known as Easter Island) and New Caledonia have revealed undescribed species from mesophotic and deeper depths. This includes three new species from Rapa Nui, Hacelia raaraa, Linckia profunda (Ophidiasteridae), Uokeaster ahi (Asterodiscididae) and two new species from New Caledonia, Astroglypha pyramidata n. gen....

The full mitogenome of an ethanol-preserved museum specimen of Ceramaster japonicus was determined using the NGS Illumina MiSeq platform. The specimen was collected from Tosa Bay, Japan, facing the Pacific Ocean (33.0781 N 134.0601 E), at 700 m depth in 2011. The mitogenome shows a typical metazoan genomic structure, with all of the 37 genes includ...

Four newly described species, Astrochlamys timoharai sp. nov. (Gorgonocephalidae Ljungman, 1867), Ophiosteira lissopatella sp. nov. (Ophiopyrgidae Perrier, 1893), Ophiophyllum umbonatum sp. nov. (Ophiopyrgidae), and Soliophis bakeri sp. nov. (Ophioscolecidae Lütken, 1869) with a description of Soliophis gen. nov., are reported from the Ross Sea and...

Exploratory cruises by the NOAA Ship Okeanos Explorer have resulted in a substantial contribution in our understanding of deep-sea echinoderm biodiversity, biology, and ecology in the North Atlantic. This includes the description and in situ feeding observations of two, new corallivorous goniasterid species, Evoplosoma nizinskiae n. sp. and Sibogas...

Japanese waters contain a highly diverse echinoderm fauna including many undiscovered species, especially in deeper-water settings. Molecular phylogenetic data has shown a close relationship between three established families of asteroids, the Asterinidae, the Solasteridae and the Ganeriidae, which are three groups that are well-represented in the...

Our recent morphological studies on the echinoderm collection of the National Museum of Nature and Science, Tokyo (NMST), indicated that the goniasterid starfishes Ceramaster japonicus (Sladen, 1889) and Ceramaster patagonicus (Sladen, 1889) are distributed in the Pacific Oceanside of Japan. In this study, we studied the NMST samples of C. japonicu...

The Derwent River seastar, ‘Marginaster’ littoralis (Echinodermata: Asteroidea), has been assessed as critically endangered owing to its highly restricted range within one estuary in Tasmania, Australia. However, there have been concerns about the validity and status of the species. Here, we use non-invasive X-ray computed tomography to review the...

Modern goniasterids are the most numerous of living asteroids in terms of described genera and species and they have important ecological roles from shallow to deep-water marine habitats. Recent MNHN expeditions and historical collections in the USNM have resulted in the discovery of 18 new species, three new genera and multiple new occurrence reco...

The present dataset is a compilation of georeferenced occurrences of asteroids (Echinodermata: Aster-oidea) in the Southern Ocean. Occurrence data south of 45°S latitude were mined from various sources together with information regarding the taxonomy, the sampling source and sampling sites when available. Records from 1872 to 2016 were thoroughly c...

Multi-locus phylogenetic studies of echinoderms based on Sanger and RNA-seq technologies and the fossil record have provided evidence for the Asterozoa-Echinozoa hypothesis. This hypothesis posits a sister relationship between asterozoan classes (Asteroidea and Ophiuroidea) and a similar relationship between echinozoan classes (Echinoidea and Holot...

Recent assignment of some goniasterid-like Ophidiasteridae into the Goniasteridae has led to further re-evaluation of other ophidiasterids as possible goniasterids. This led to the discovery of new genera and species supported by a distinctive set of characteristics which support a new subfamily, the Ferdininae, a group originally outlined by Marsh...

Background There is growing interest in mining polymetallic nodules from the abyssal Clarion-Clipperton Zone (CCZ) in the tropical Pacific Ocean. Despite being the focus of environmental studies for decades, the benthic megafauna of the CCZ remain poorly known. In order to predict and manage the environmental impacts of mining in the CCZ, baseline...

Research cruises by the Monterey Bay Aquarium Research Institute (MBARI) have resulted in the discovery of three new species of asteroids from the lower bathyal/abyssal regions of the North Pacific. A new genus, Bathyceramaster is described to accommodate "Mediaster" elegans Ludwig 1905 and related species. New records and in situ observations are...

The paths animals take while moving through their environments affect their likelihood of encountering food and other resources; thus, models of foraging behavior abound. To collect movement data appropriate for comparison with these models, we used time-lapse photography to track movements of a small, hardy, and easy-to-obtain organism, Aquilonast...

The paths animals take while moving through their environments affect their likelihood of encountering food and other resources; thus, models of foraging behavior abound. To collect movement data appropriate for comparison with these models, we used time-lapse photography to track movements of a small, hardy, and easy-to-obtain organism, Aquilonast...

We present data from a DNA taxonomy register of the abyssal benthic Echinodermata collected as part of the Abyssal Baseline (ABYSSLINE) environmental survey cruise 'AB01' to the UK Seabed Resources Ltd (UKSRL) polymetallic-nodule exploration claim 'UK-1' in the eastern Clarion-Clipperton Zone (CCZ), central Pacific Ocean abyssal plain. Morphologica...

Taxa table

Tree file from Crinoidea phylogenetic analyses

Tree file from Ophiuroidea phylogenetic analyses

Tree file from Asteroidea phylogenetic analyses

Tree file from Holothuroidea phylogenetic analyses

Energy availability has long been recognized as a predictor of community structure, and changes in both terrestrial and marine productivity under climate change necessitate a deeper understanding of this relationship. The productivity-diversity relationship (PDR) is well explored in both empirical and theoretical work in ecology, but numerous quest...

The interactions between fauna and sea-disposed munitions provide important evidence regarding whether munitions constituents affect the health of the ocean environment and its inhabitants. To date few studies of these interactions have been conducted at deep-water disposal sites; typically observations of fauna in the vicinity of sea-disposed muni...

Based on a phylogenetic analysis of undescribed taxa within the Forcipulatacea, a new family of deep-sea forcipulatacean starfishes, Paulasteriidae fam. nov., is described from deep-sea settings. Paulasterias tyleri gen. et sp. nov. was observed at recently documented hydrothermal vents on the East Scotia Ridge, Southern Ocean. A second species, Pa...

The Antillean Cenozoic fossil record of asteroids comprises mainly dissociated ossicles. Most common among isolates from upper Oligocene deposits of Jamaica and Antigua are marginal ossicles of an extinct, indeterminate species of Pycinaster. This is the youngest known occurrence of the genus and the first from beyond Europe. A number of relatively...

A new species of corallivorous goniasterid, Evoplosoma watlingi n. sp., from Bear Seamount in the North Atlantic is described in conjunction with an overview of other species within the genus Evoplosoma. Hippasteria tasmanica McKnight, 2006 is re-classified within Evoplosoma. In situ images of Atlantic deep-sea Goniasteridae, including Evoplosoma s...

Two new species of Goniasteridae, Astroceramus eldredgei n. sp. and Apollonaster kelleyi n. sp. are described from the Hawaiian Islands region. Prior to this occurrence, Apollonaster was known only from the North Atlantic. The Goniasteridae is the most diverse family of asteroids in the Hawaiian region. Additional in situ observations of several go...

A new species of Brisingenes, Brisingenes margoae nov. sp. is described from the HUMMA Study Area [see overview Edwards et al. (2015a), this issue], Oahu in the Hawaiian Islands. This represents a range extension for Brisingenes to the North Pacific and is the fifth-known brisingid species in the Hawaiian region. An overview of other Hawaiian brisi...

We report new geographical and bathymetric occurrence information for several species of brisingidan asteroids (Asteroidea: Brisingida) in eastern Canada. We recorded Brisinga costata, Freyella microspina and Novodinia americana in Newfoundland and Labrador (NL), extending the geographical ranges of these species northward. Brisinga costata and F....

A molecular phylogenetic analysis of the genus Hippasteria, rooted against Evoplosoma, has provided the basis for taxonomic revisions and provided insight into the biogeography of a widely occurring, cold-water group of corallivorous asteroids. Herein, we describe three new species, Hippasteria mcknighti sp. nov., Hippasteria muscipula sp. nov., an...

New molecular phylogenetic data and new specimens provide the basis for a revision of the family Poraniidae. We present molecular phylogenetic data for five out of 11 genera in the Poraniidae including a newly discovered taxon from the North Pacific. Bathyporania ascendens nov. gen., nov. sp., is described from Davidson Seamount (35º43'N, 122º43'W)...

A new, morphologically based classification of extant asteroids with comments on select fossils was published by A.S. Gale. Research approaches used limited sampling, and much literature treatment is not accurate and therefore misleading. We review these concerns, seeking to clarify argumentation on differing interpretations.

doi: 10.1890/12-1950.1

Genetic structure and connectivity of populations of the globally distributed and eurybathic sea star Hippasteria phrygiana (Parelius 1768) were studied in 165 individuals sampled from three oceanic regions: the North Pacific Ocean, the South Pacific Ocean (considered to include the adjacent regions of the Southern Ocean and the southern Indian Oce...

a b s t r a c t In 2008 the BIOPEARL II expedition on board of RRS James Clark Ross sailed to the eastern Amundsen Sea Embayment and Pine Island Bay, one of the least studied Antarctic continental shelf regions due to its remoteness and ice cover. A total of 37 Agassiz trawls were deployed at depth transects along the continental and trough slopes....

Newly collected specimens of the Atlantic Myxaster sol and a further record of Pythonaster atlantidis add to the known occurrence records and the morphological variation of these rarely encountered species. Distribution data suggests that both M. sol and P. atlantidis are pan-Atlantic species and are similar to other widely distributed deep-sea ast...

Echinoderms are well represented in nearshore hard-bottom (< 100 m depth) habitats along the Antarctic Peninsula where they are presumably important contributors to benthic production, carbon flow, and determinants of community structure. The present study assesses the densities of echinoderms at shallow depths (2–15 m) at five sampling sites withi...

Background: The question of how many marine species exist is important because it provides a metric for how much we do and do not know about life in the oceans. We have compiled the first register of the marine species of the world and used this baseline to estimate how many more species, partitioned among all major eukaryotic groups, may be disco...

The marine invertebrates barcoding effort engaged at the MNHN contributed to many different projects. First, an unprecedented sample of Antarctic crinoids has been barcoded revealing probable cryptic speciation within different taxa. For example, seven sympatric COI lineages can be distinguished within the broadcaster Promachocrinus kerguelensis, a...

Members of the Asteroidea (phylum Echinodermata), popularly known as starfish or sea stars, are ecologically important and diverse members of marine ecosystems in all of the world's oceans. We present a comprehensive overview of diversity and phylogeny as they have figured into the evolution of the Asteroidea from Paleozoic to the living fauna. Liv...

Newly collected specimens of the Atlantic Myxaster sol and a further record of Pythonaster atlantidis add to the known occurrence records and the morphological variation of these rarely encountered species. Distribution data suggests that both M. sol and P. atlantidis are pan-Atlantic species and are similar to other widely distributed deep-sea ast...

The Southern Ocean is considered to be the canary in the coal mine with respect to the first effects of ocean acidification (OA). This vulnerability is due to naturally low carbonate ion concentrations that result from the effect of low temperature on acid-base dissociation coefficients, from the high solubility of CO2 at low temperature, and from...

During a series of cruises aboard the R/V "El Puma" aimed at collecting the deep–water benthic and pelagic fauna off the Pacific coast of Mexico, in the eastern Pacific, samples of Asteroidea were collected below 500 m depth (587–1 526 m). A total of 335 specimens were collected, belonging to 18 species, 14 identified to species, 3 to genus, and 1...

During a series of cruises aboard the R/V "EI Puma" aimed at collecting the deep-water benthic and pelagic fauna off the Pacific coast of Mexico, in the eastern Pacific, samples of Asteroidea were collected below 500 m depth (587-1 526 m). A total of 335 specimens were collected, belonging to 18 species, 14 identified to species, 3 to genus, and 1...

We present a comprehensively sampled three-gene phylogeny of the monophyletic Forcipulatacea, one of three major lineages within the crown-group Asteroidea. We present substantially more Southern Hemisphere and deep-sea taxa than were sampled in previous molecular studies of this group. Morphologically distinct groups, such as the Brisingida and th...

The Valvatacea is one the most ecologically important, taxonomically diverse, and widespread groups of post-Palaeozoic (i.e. modern) Asteroidea. Classification within the group has been historically problematic. We present a comprehensively sampled, three-gene (12S, 16S, early-stage histone H3) molecular phylogenetic analysis of the Valvatacea. We...

The Dumont d’Urville Sea (East Antarctic region) has been less investigated for DNA barcoding and molecular taxonomy than other parts of the Southern Ocean, such as the Ross Sea and the Antarctic Peninsula. The Collaborative East Antarctic MARine Census (CEAMARC) took place in this area during the austral summer of 2007–2008. The Australian vessel...

The Dumont d’Urville Sea (East Antarctic region) has been less investigated for DNA barcoding and molecular taxonomy than other parts of the Southern Ocean, such as the Ross Sea and the Antarctic Peninsula. The Collaborative East Antarctic MARine Census (CEAMARC) took place in this area during the austral summer of 2007–2008. The Australian vessel...

A review of high-latitude Goniasteridae south of 50°S is presented, including a key to species, figures and taxonomic descriptions of all species with a brief taxonomic summary for all genera. Nineteen species in 11 genera are reviewed. Era-tosaster jenae nov. gen and sp., Chitonaster trangae nov. sp., and Pillsburiaster calvus nov. sp. are describ...

Au cours des quatre-vingts dernières années plus de 30 campagnes ont été effectuées aux îles Kerguelen (Hureau, 2011), cependant peu de ces campagnes ont permis de récolter du benthos. Ainsi 1961 et 1970, des récoltes benthiques ont été initiées par P. Arnaud, R. Délepine, J.C. Hureau et M. Rannou. Ces récoltes localisées essentiellement en milieu...

The Hippasterinae is a subfamily within the Goniasteridae, consisting of five genera and 26 species, which occur in cold-water settings ranging from subtidal to abyssal depths. All known genera were included in a cladistic analysis resulting in two most parsimonious trees, supporting the Hippasterinae as monophyletic. Our review supports Sthenaster...

The last decade has seen an increase in the frequency and breadth of application of molecular tools, many of which are beginning to shed light on long-standing questions in biogeography and evolutionary history of marine fauna. We explore new developments with respect to Arctic marine invertebrates, focusing on molecular taxonomy and phylogeography...

Paralogous genes frequently show differences in patterns and rates of substitution that are typically attributed to different selection regimes, mutation rates, or local recombination rates. Here, two anciently diverged paralogous copies of the histone H3 gene in sea stars, the tandem-repetitive early-stage gene and a newly isolated gene with lower...

Patterns of nucleotide substitution differ between marine species that have a pelagic feeding (planktotrophic) larval stage and related species that lack such a stage, for both adaptive and non-adaptive reasons. Here, patterns of nucleotide and inferred amino acid substitution are analyzed for the tandem-repetitive early-stage histone H3 gene in 36...

Although numerous coastal marine species show intra-specific lineage splitting and population divergence times that date to the period of glacial cycles during the Pleistocene epoch, reported instances of recent speciation in the coastal marine environment are relatively rare. Marine organisms with brood-protection and other reproductive modes with...

The Zoroasteridae comprise a small but widespread family of asteroids distributed throughout the deep sea. Although poorly understood, they are often collected in the hundreds, suggesting that they occupy important ecological roles. A phylogenetic analysis including 24 terminal taxa and 70 morphological characters was performed, resulting in a sing...