Content uploaded by M. Antonio Todaro
Author content
All content in this area was uploaded by M. Antonio Todaro
Content may be subject to copyright.
Marine gastrotrichs from the sand beaches of the northern Gulf of Mexico: species list and distribution
Abstract
In this meio-faunistic survey along the northern coast of the Gulf of Mexico, gastrotrichs were found in sand collected mostly from beaches on barrier islands. Sediment from Florida and Alabama contained the largest species number. South Texas collecting sites also hosted a very diverse gastrotrich fauna. Paucitubulate Chaetonotida, previously unreported from the area, accounted for about one half of the 45 species encountered. After comparing local specimens also with high resolution videosequences of individuals collected from distant geographic regions, the amphi-Atlantic and/or cosmopolitan distribution of 27 of these species, is confirmed.
... Gastrotrichs are mainly interstitial in marine habitats, whereas in freshwater they are also found as ubiquitous components of the periphyton and benthos (Balsamo and Todaro Musellifer are known to inhabit deep-sea muddy substrata (Hummon 1969;Leasi and Todaro 2010). In marine sandy bottoms, gastrotrichs typically rank third in abundance among the meiofaunal taxa behind the Nematoda and the harpacticoid Copepoda (e.g., density up to 364 ind./10 cm 2 ; Todaro 1998), although in several instances, they have been found to be the first or the second most abundant meiofauna taxon (e.g., Coull 1985;Gray 1971;Hochberg 1999;Todaro et al. 1995). ...
... Like most other meiobenthic organisms they have a short life cycle and lack larval stages useful for dispersal; consequently, marine gastrotrichs spend their entire existence within the sediments. Despite this life history, many species are not restricted to confined areas; on the contrary, they seem to be widely distributed, with some species being amphi-Atlantic or cosmopolitan (e.g., Todaro et al. 1995;Todaro and Rocha 2004; see also Artois et al. 2011). In the last decade, the widespread availability of novel techniques, such as high-resolution microscopy and gene sequencing, allows for a better comparison at morphological and/ or genetic levels of specimens from distant areas, and have stimulated interest in the taxonomy, phylogeny and biogeography of these marine worms (e.g., Curini-Galletti et al. 2012;Hochberg et al. 2014;Hummon 2011;Kieneke et al. 2012Kieneke et al. , 2013aKolicka et al. 2015;Leasi and Todaro 2009;Schuster et al. 2017;Todaro et al. 2015a). ...
... In this, Table 2 Gastrotricha Chaetonotida, species list and distribution along the eastern coast of Lanzarote Taxon Sampling station CHAETONOTIDA 1 5 7 10 13 16 17 18 27 29 30 32 34 35 36 37 Chaetonotidae Aspidiophorus marinus Lanzarote shares some similarities with areas of the world where gastrotrichs have been studied to a good extent and where members of the suborder account for about 40% of the total gastrotrich fauna, e.g., Italy 154 spp., 59% M and 41% C , Belgian coast (37 spp., 62% M, 38% C; Jouk et al. 1992) and Sweden (54 spp., 66% M and 34% C; Willems et al. 2009;Todaro et al. 2010 and unpublished). A higher percentage of chaetonotidans is reported for the Gulf of Mexico (45 spp., 53% M and 47% C, Todaro et al. 1995) and the Caribbean island of St John (70 spp., 50% M and 50% C, . So far only in Greece do the chaetonotidans outnumber macrodasyidans (63 spp., 21 M and 42 C; Hummon and Roidou 1995). ...
Sampling campaign took place in October 2011 and included 7 locations and 16 stations along the eastern coast of the island of Lanzarote (Spain). Samples yielded 61 species for a total of 96 records. Thirty-six species (27 genera and 11 families) belong to Macrodasyida while 25 species (18 genera, 7 families) to Chaetonotida. Thirty-two are known species while 29 appear to be undescribed taxa or putatively so. The finding at Lanzarote of some of the known species bear particular significance: Oregodasys cirratus and Tetranchyroderma canariense are recorded for the second time ever, while Musellifer delamarei and Urodasys acanthostylis were previously known only from the Mediterranean, and Urodadys mirabilis was acknowledged only for northern Europe. Furthermore, the presence of Chaetonotus apechochaetus, C. apolemmus, C. siciliensis, Heterolepidoderma loricatum, Lepidodasys unicarenatus, Musellifer delamarei, Thaumastoderma mediterraneum, and Urodasys acanthostylis strongly suggest them to be part of the temperate/warm fauna that invaded the Mediterranean basin after the Missinian crisis during the different climate eras. Of the new species, one is described as its characteristics substantially widen our knowledge of the entire genus. Urodasys completus sp. nov. is unique in that it possesses, among others, two testes and a sclerotic stylet. Results of a phylogenetic analysis indicated that the sequence of the evolutionary transformation that have occurred in the reproductive system of the species of Urodasys are likely dissimilar from the ones proposed thus far. The overall results testify the need to continue the exploration in the Canary Islands.
... Based on the suggestions by Todaro & Rocha (2004 we tested the alternative hypothesis that different sediments, locations, and zones would contain different assemblages of gastrotrichs (both orders), Macrodasyida (only), and Chaetonotida (only). Few studies aiming to elucidate the biogeography of Gastrotricha have been conducted thus far (e.g., Todaro et al., 1995Todaro et al., , 1996Kieneke et al., 2012), but the existing works have reported the existence of high percentage of cosmopolitan species and some level of cryptic diversity within the phylum (Kieneke et al., 2012). ...
... As reported often before (e.g., Todaro et al., 1995;Todaro & Rocha, 2004Hochberg, 2008), gastrotrich species richness is negatively correlated with high organic content and small sediment grain size. Todaro & Rocha (2011) stated that the biodiversity of Gastrotricha in the state of São Paulo will become better known as new localities with clear water (little suspended matter in the water column) and fine-to medium-grained sediments are investigated. ...
Broad spatial variations of biodiversity are associated with patterns and processes at different scales, and are well known for large terrestrial animals. For the interstitial microscopic fauna a wide distribution conception is accepted for several phyla. This assumption is being revised since more information has become available on their biogeography and general macroecological threats. This study analyzed the variability of marine Gastrotricha diversity among benthic habitats and localities along the Brazilian coast. We tested the hypothesis that sediment textures, location, tidal zones, and their interactions, are potential explanatory variables that affect the Gastrotricha diversity. Richness estimates, species composition, and beta diversity were used as response variables of biodiversity. The number of gastrotrichs, macrodasyids, and chaetonotids species was mostly explained by sediment sorting and the highest richness was detected in poorly sorted sediments. Species composition and beta diversity were correlated with tidal zone, location, and average grain size, and the highest turnover of species was expected on islands. The general diversity patterns observed in our study that were explained by sediment textures, tidal zones, and localities, are expected to be observed along other marine coastlines in the world and may be correlated with sediment transport and deposition processes.
... The Tropical Northwestern Atlantic (TNWA) has seen an increase in descriptions of new species of marine Gastrotricha ever since Hummon (2010) published his review of Caribbean species. To date, more than 70 species have been reported from the five regions that compose the TNWA (Renaud-Debyser 1963;Thane-Fenchel 1970;Hummon 1974;Schöpfer-Sterrer 1974;Kisielewski 1984;Decho et al. 1985;Evans & Hummon 1991;Evans 1992Evans , 1994Todaro 1994;Todaro et al. 1995;Hochberg 2008Hochberg , 2010Hummon 2010;Hochberg & Atherton 2011;Atherton & Hochberg 2012;Kånneby et al. 2012;Todaro et al. 2012a;Atherton 2014). ...
A new gastrotrich species of the genus Crasiella (Macrodasyida: Planodasyidae) is described from Capron Shoal, Florida, USA. The new species is up to 520 μm long and differs from its congeners in the position of adhesive tubes and the structure of its spermatozoa. There are nine TbA that insert ventrally on the head plus an additional pair of TBA that insert medially. Up to 42 TbVL per side. Six pairs of TbP insert on a pair of caudal pedicles. Animals are simultaneous hermaphrodites with an elongated frontal organ and large caudal organ. The spermatozoa have a tripartite acrosome unlike others in the genus that have a four-part acrosome.
... In freshwater habitats, gastrotrichs are members of the benthos and periphyton and, to a limited degree, also of the plankton and psammon. In marine settings, these tiny animals inhabit (mostly) the interstice of the sandy habitats and are usually the third group in density among the interstitial meiofaunal taxa, behind the nematodes and the harpacticoid copepods (e.g., abundance up to 364 ind./10 cm 2 ) [1]; however, several studies have found them to be the second or the first most abundant meiobenthic group [2][3][4][5]. In inland waters, the group usually figures among the top five most abundant taxa, and populations may attain a density of 2600 ind./10 cm 2 [6]. ...
Gastrotricha is a group of meiofaunal-sized, free-living invertebrates present in all aquatic ecosystems. The phylum includes over 860 species globally, of which 505 nominal species have been recorded in marine sandy sediments; another 355 taxa inhabit the freshwater environments, where they are recurrent members of the periphyton and epibenthos, and, to a lesser degree, of the plankton and interstitial fauna. Gastrotrichs are part of the permanent meiofauna and, in general, they rank among the top five groups for abundance within meiobenthic assemblages. The diversity, abundance, and ubiquity of Gastrotricha allow us to suppose an important role for these animals in aquatic ecosystems; however, ecological studies to prove this idea have been comparatively very few. This is mainly because the small size and transparency of their bodies make gastrotrichs difficult to discover in benthic samples; moreover, their contractility and fragility make their handling and morphological survey of the specimens rather difficult. Here we offer an overview, describe the basic techniques used to study these animals, and provide a key to known genera in an attempt to promote easy identification and to increase the number of researchers who may be interested in conducting studies on this understudied ecological group of microscopic organisms.
... These specimens are described herein as three new species. In all cases, animals were found in sublittoral sand collected using 500 ml plastic jars 39 Use and handling of the animals subject of the present study (Gastrotricha) is not regulated/prohibited; furthermore, collection from the wild does not require special authorization if carried out in public areas (beaches) as it was in the present case. sample processing and morphological analysis. ...
Macrodasyida (phylum Gastrotricha) comprises 365 species distributed across 34 genera and 10 families. However, current classification is under revision due to the contradictory results of molecular and morphological cladistic analyses. Studies aimed at bridging the gaps took advantage of supplementary assessments of poorly known species and particularly from observations of new taxa showing original traits that could help to identify plesiomorphic character states in these anatomically diverse micrometazoa. We follow this path by describing three new interesting macrodasyidan species respectively from Italy, Brazil and Sweden. In many respects, the new species resemble most closely species of the genus Macrodasys; however, details of the external morphology, in combination with the different lay-out of the reproductive system and the tiny spermatozoa lacking a visible flagellum, suggest they belong to a new genus, possibly in the family Macrodasyidae. These hypotheses are supported by the phylogenetic relationships of 47 taxa inferred from analyses of the 18S rRNA gene, which found the new species clustering with Thaidasys tongiorgii in a subset of a larger clade containing Macrodasys. Accordingly, the establishment of the following taxa is proposed: Kryptodasys gen. nov., K. marcocurinii sp. nov., K. carlosrochai sp. nov. and K. ulfjondeliusi sp. nov.
... In North America, three species of Pseudostomella were found by Ruppert (1970) in North Carolina: Pseudostomella plumosa Ruppert 1970, P. cataphracta Ruppert 1970, and P. roscovita. Subsequently, P. roscovita and P. plumosa have been found along the coastlines of several states and are probably widespread along the Atlantic coast of the USA (Todaro et al. 1995;Hummon 2010). However, P. cataphracta had yet to be recorded from outside its type locality. ...
Pseudostomella dolichopoda was originally described from the north coast of São Paulo, Brazil,
and P. cataphracta from North Carolina, USA. Herein we report new distributional records of both species:
P. dolichopoda is recorded from Espírito Santo, Brazil and P. cataphracta from Florida, USA. An updated
identifcation key for the genus Pseudostomella is also provided
... Dispersal via long-shore currents over a long geological time combined with oceanic dispersal and continental drift may be invoked to explain biogeographic patterns of Gastrotricha distribution in many marine systems; however, indirect dispersal by phoretic , rafting and ballast may play a relevant role too. Of the 45 species found by Todaro et al. ( 1995 ) along the northern Gulf of Mexico the proportion of amphi-Atlantic/ cosmopolitan, regional and endemic species found amounted to 60, 22 and 18% respectively, most endemics being macrodasyidans. Of the 56 putative species found by Rocha ( 2004 , 2005 ) from the Brazilian beaches of the State of São Paulo, 31 (55%) could be endemics, again mostly macrodasyidans. ...
Sampling of twelve locations along the north east coast of the USA and Brazilian coasts yielded five new records of Xenotrichulidae species (Xenotrichula guadalupensis, X. carolinensis, X. intermedia, Heteroxenotrichula pygmaea and Draculiciteria tesselata) and the description of a new species of Xenotrichula, X. tropicalis sp. nov. from Brazil. The new species is unique among its congeners in possessing double edge rounded scales on the ventral edge of the pharynx and two rows of flat plates on the ventral trunk.
A Tribute to William Hummon – Gastrotrich Biologist Extraordinaire
Not since the great Adolf Remane in the
early 20th century has there been a more
influential researcher in gastrotrich systematics
thanWilliamDale ‘‘Bill’’Hummon.Bill
earnedhisPh.D. inZoology at theUniversity
ofMassachusetts,Amherst in 1969,where he
performed foundational research on the
marine gastrotrichs of New England: Distributional
ecology of marine interstitial Gastrotricha
fromWoods Hole,Massachusetts,
with taxonomic comments on previously
described species. His Ph.D. research was
the beginning of a life-long dedication to
Gastrotricha, that enigmatic group of beautiful,
meiofaunal invertebrates that have
captured the attention of zoologists worldwide,
and continue to inspire scientists in
their quests to understand some of the
greatest mysteries of animal evolution. Bill
went on to become an inspiring professor of
marine biology and zoology at OhioUniversity,
Athens in 1969 (until 2002), and during
his tenure participated in several international
fellowships England, Scotland, and Egypt. Bill’s impact
onthe discipline grewwith each passing year,
having supervised 11 M.S. students, two
Ph.D. students, 3 postdoctoral researchers,
and producing 110 publications on ecology,
ecotoxicology, morphology, taxonomy and
the philosophy of science.Over the course of
43 illustrious years, he worked with gastrotrichs,
copepods, crayfish, insects, rotifers,
and tardigrades, and described 2 families, 6
genera, and 105 species along the way. Bill’s
focus on marine Gastrotricha allowed him
the rare (and envious) opportunity to travel
across some of the most historic and
beautiful coastal landscapes of the Azores,
Belgium,France,Germany,Greece, Ireland,
Israel, Italy, Poland, Portugal, the United
Kingdom, the Caribbean, and Central and
South America. And while his quest to
understand gastrotrichs almost always had
a global component, this did not mean he
ignored his own backyard. Bill’s research on
the meiofauna of the east and west coasts of
the United States remains some of his most
influential taxonomic work on the phylum,
and even included studies of the effects of
pollutants, such as DDT and mine acids, on
freshwater gastrotrichs.ButwhetherBill was
traversing the USA in his mobile lab (his
vehicle full of portable microscopes and
equipment) or traveling across vast oceans
and seas, he always kept one eye on the sand
and one eye on the microscope.
Bill’s importance to gastrotrich research
went well beyond his influential publications
on ecology and systematics. He also highlighted
the very real and very practical
problem of conserving type specimens for
natural history museums, which is nothing
short of impossible when dealing with softbodied
meiofauna. Bill’s hand-drawn illustrations
of species always made identification
relatively easy for the uninitiated, but
without good physical specimens in museum
collections, one could never be sure if
the animal found on one beach was the
same as that on another. Nowadays,
molecular sequencing is the preferred choice
for species synonymy (and differentiation),
but this requires a dedicated lab, skills, and
most importantly, funding, which can be in
short supply for those who work on
meiofauna. Bill’s solution to this dilemma
predated the molecular revolution and in
fact was much simpler, and importantly,
globally accessible via the Internet. He
provided the first video recording (SVHS
format) of a new taxon, Prostobuccantia
broca Evans & Hummon, 1991, which was
deposited in the National Museum of
Natural History, Washington, DC (USNM
235577). Since then, Bill has made innumerable
video recordings (in digital format) of
new and known species from across the
globe, and provided his followers hours
(and gigabytes) of video data, photographic
images, GPS coordinates, maps, and taxon
lists that remain as influential as any DNA
barcode. Originally posted on a dedicated
server, Bill’s works are now part of the
Gastrotricha World Portal (http://www.
gastrotricha.unimore.it/moviegallery.htm).
Bill’s influence on our scientific understanding
and appreciation of Gastrotricha
cannot be overstated. He inspired scientists
across the globe, many of whom have
never had the chance to meet this extraordinary
man, yet will continue to learn from
him well into the 21st century and beyond.
Bill’s legacy will live on the annals of
scientific discovery, and in the fond memories
of those who knew him and will never
forget. We are pleased to dedicate this
special collection of gastrotrich publications
to his memory.
Fourteen species of Macrodasyoidea (Gastrotricha), collected from the Somalian coast have been described. Four species belonged to the genus Macrodasys, four to the genus Tetranchyroderma, and the other six species belonged to the genera Urodasys, Paraturbanella, Dendrodasys, Thaumasto- derrna, Diplodasys and Pseudostomella. Seven species substantially fitted previous descriptions, while the other seven species appear to be new, however, because our observations were all performed on living specimens we refrain from naming new species.
Twelves species of Gastrotricha Chaetonotoidea collected from the Somalian coast are described. Two species belong to the genus Heteroxenotrichula, three to Chaetonotus, one to Halichaetonotus, two to Heterolepidoderma, and four to Aspidiophorus. Eight species substantially fit previous descriptions. The other four species appear to be new. However, they were not named because all observations were made on living specimens and no holotype could be prepared.
Two new species of Thaumastoderma (Gastrotricha, Macrodasyida) are described from the Bergen area, western Norway. Th. truncatum sp. n. inhabits shell gravel of exposed places; Th. bifurcatum sp. n. is mostly found in finer sediments of less exposed places, and is reported also from the Trondheim and Tromsø areas. Both species have one pair of spatulate tentacles and lack eyespots. Th. truncatum can be distinguished from other members of the genus by these characters: six pairs of dorsal cirri, fourth pair being especially long; looped vas deferens. Th. bifurcatum is distinguished by long posterior dorsal cirri and a long adhesive tubule directly below, with the impression of a double ‘furca’. A key to the species is included.
Meiobenthology is the science of the tiny animals that live in huge numbers in all aquatic sediments. This fully revised and enlarged second edition emphasizes new discoveries and developments in this field. Major progress has been made in three general areas: Systematics, diversity and distribution Ecology, food webs, and energy flow Environmental aspects, including studies of anthropogenic impacts The meiobenthos of polar and tropical regions, deep-sea bottoms and hydrothermal vents are now studied in more detail. The high number of species found to survive under such extreme conditions puts them at the forefront of biodiversity studies. Molecular screening methods enable large numbers to be analyzed upon applying reasonable effort. The aim of this book is to synthesize these modern scientific achievements such that meiobenthology can play a key role in aquatic research and in assessing the health of our environment. From the reviews of the first edition: "Giere's scholarly but readable monograph on the meiobenthos will be welcomed by all aquatic benthic ecologists." Nature "Every librarian and every practicing meiobenthologist should have a copy of this book." Journal of Experimental Marine Biology and Ecology.