Elizabeth Walsh

University of Texas at El Paso | UTEP · Department of Biological Sciences

We report a dataset of all known and published occurrence records of animals of the phylum Rotifera, including Bdelloidea, Monogononta, and Seisonacea (with the exclusion of Acanthocephala) for Africa and surrounding islands and archipelagos. The dataset includes 24,704 records of 914 taxa (subspecies: 38; species: 783; genus: 76; family: 17), gath...

The retrocerebral organ (RCO) is a complex glandular system that is widely distributed across species of phylum Rotifera (sensu stricto). This system is hypothesized to secrete mucus that aids in benthic locomotion, adhesion, and/or reproduction. Unfortunately, the ultrastructure of the RCO is mostly unknown, having only been partially examined in...

The rotifer fauna of Africa has been studied for >100 years, but there has been no recent synthesis. We compiled data from 265 publications that reported information on African rotifers. Our dataset yielded information on the distribution of 765 taxa from ~1850 separate sites; these included both natural and artificial habitats such as lakes, ponds...

The aquatic microfauna of Africa is poorly characterized, especially in the case of planktonic rotifers inhabiting waterbodies other than large lakes. In addition, little is known about factors that structure these communities. Here, we assessed the roles of climatic region, habitat type, macrophyte abundance, and a suite of abiotic environmental f...

Understanding how local conditions and dispersal dynamics structure communities of passively dispersing aquatic invertebrates remains uncertain, especially in aridland systems. In these systems, dispersal is irregular and successful colonization is subject to priority effects. To investigate these factors, we compared rotifer species composition fr...

Aim The long history of isolation of the Antarctic continent, coupled with the harsh ecological conditions of freezing temperatures, could affect the patterns of genetic diversity in the organisms living there. We aim (a) to test whether such pattern can be seen in a mitochondrial marker of bdelloid rotifers, a group of microscopic aquatic and limn...

Secretion of an extracorporeal hydrogel is a common defensive strategy employed by many aquatic invertebrates including several species of sessile rotifers. Here, we provide a comparative study of the ultrastructure of the gelatinous secretions of four species of Superorder Gnesiotrocha (Monogononta): Conochilus unicornis, Collotheca ferox, Stephan...

The phylum Rotifera comprises two disparate groups. Traditionally, rotifers were viewed as a small taxon of tiny, bilaterally symmetrical, unsegmented aquatic invertebrates. However, recent molecular analyses indicate that Acanthocephala, a group of obligatorily parasitic worms, are highly modified rotifers. (They are covered separately in the ELS....

Our understanding of the ecological drivers that control community structure of benthic rotifers is poorly known. By reviewing 21 papers on freshwater benthic rotifers we compiled an inventory of an additional 258 species, 27 genera, and six families not previously listed in the review of benthic, lotic rotifers by Ricci and Balsamo (Freshw Biol 44...

Cupelopagis vorax is a sessile, predatory rotifer with indirect development. The topology of its nervous system is partly known through histological examination of the female adult. However, there is no information on the larval stage, and so, no understanding of how metamorphosis might affect the configuration of neurites. Here, we use immunohisto...

Desert aquatic systems are widely separated, lack hydrologic connections, and are subject to drought. However, they provide unique settings to investigate distributional patterns of micrometazoans, including rotifers. Thus, to understand rotifer biodiversity we sampled 236 sites across an array of habitats including rock pools, springs, tanks, flow...

This work presents the taxonomy, morphology and distribution of the free-living, freshwater copepods that inhabit ephemeral aquatic habitats in one binational reserve known as the Chihuahuan Desert. This work represents the largest effort to study this group in desert-related aquatic habitats to date. The copepod fauna of freshwater systems in the...

Rotifers are diverse and abundant aquatic micrometazoans that rely on their ciliated apical end (corona) for locomotion and feeding. In order Collothecaceae, which includes mostly sessile species, larval rotifers go through a complex metamorphosis after settlement wherein they replace their corona with an unusual cup-shaped head that functions excl...

Small birefringent concretions have been reported in rotifers for over a century and often hypothesized as energy sources. Here, we provide an update on their distribution in superorder Gnesiotrocha and the first data on their ultrastructure. Within Gnesiotrocha, these birefringent bodies (BRB) are known from at least ten species of Collothecaceae...

Although the theoretical underpinnings of habitat selection by marine invertebrate larvae have been well studied, this theory has been neglected for freshwater sessile rotifers. To study how substratum selection affects larval fitness, we developed a dynamic model to examine influences of three elements of larval life (survival, substratum acceptan...

Gnesiotrochan rotifers display a variety of life styles ranging from taxa with free-swimming larval and sessile adult stages to those with motile adult stages and colonial habits. Several explanations for the C-value enigma posit that genome size is correlated with lifestyle. To investigate this, 13 gnesiotrochan species representing nine genera we...

Morphological approaches may not provide sufficient resolution for species delineation. Thus, we used an integrated approach that included molecular and ecological characters as well as morphological features to gain a better estimate of species diversity and to improve our understanding of the speciation process within rotifers. Previously, seven...

The Training in Environmental Research and Academic Success (TIERA) program was created to increase recruitment and retention of environmental science majors at the University of Texas at El Paso, where ∼80% of students self-declare Hispanic origin, providing a unique opportunity to increase diversity in the future STEM workforce. Through curriculu...

• Dry, ephemeral, desert wetlands are major sources of windblown sediment, as well as repositories for diapausing stages (propagules) of aquatic invertebrates. Zooplankton propagules are of the same size range as sand and dust grains. They can be deflated and transported in windstorm events. This study provides evidence that dust storms aid in disp...

Rotifers that engage in cyclical parthenogenesis produce two types of eggs: subitaneous eggs that hatch as clonal females and meiotic eggs that hatch as haploid males, or if fertilized, as females after a period of diapause (resting eggs). The ultrastructure of resting eggshells is known for some motile species, but there are limited data on subita...

Based on observations of preserved samples, Jaramillo-Londoño & Pinto-Coelho (2010) describe a putative ecological relationship between the rotifer Hexarthra intermedia and the cladoceran Bosmina longirostris as a fusion of parasitism and interference competition. They argue that H. intermedia enter the filtering chamber of B. longirostris allowing...

Microorganisms, including rotifers, are thought to be capable of long distance dispersal. Therefore, they should show little population genetic structure due to high gene flow. Nevertheless , substantial genetic structure has been reported among populations of many taxa. In rotifers, genetic studies have focused on planktonic taxa leaving sessile g...

Representative trophi from cryptic species of Limnias melicerta and L. ceratophylli. Trophi of cryptic species E, G, I, K, L and M from L. melicerta and trophi of cryptic species B and D from L. ceratophylli are shown. (DOCX)

Bayesian inference consensus phylogenetic tree based on partial 18S rRNA sequences of 17 populations of Limnias melicerta and 18 populations of L. ceratophylli. Average branch lengths are proportional to the number of substitutions per site under a JC substitution model. At each node, posterior probabilities > 0.80 are shown. Abbreviations as in S1...

Site and date of collection of Limnias melicerta populations and outgroup taxa. GenBank accession numbers for their corresponding partial COI gene, ITS region, and partial 18S rRNA sequences are provided. Number of sequenced clonal lineages and haplotype group(s) for each population are also noted. Missing sequences are specified by “-” for haploty...

Site and date of collection of Limnias ceratophylli populations. GenBank accession numbers for their corresponding partial COI gene, ITS region, and partial 18S rRNA sequences are provided. Number of sequenced clonal lineages and haplotype group(s) for each population are also noted. Missing sequences are specified by “-” for haplotype group and Ge...

Substitution saturation test of molecular markers. Substitution saturation test for partial COI gene, ITS region, and partial 18S rRNA sequences of Limnias melicerta and L. ceratophylli populations implemented in DAMBE v 6. Iss: index of substitution saturation, and Iss.c: critical index of substitution saturation. If Iss is significantly smaller t...

Desert springs are critical for wildlife and human subsistence, but poorly studied. The springs in the northern Chihuahuan Desert region of Mexico are no exception. While groundwater overexploitation and other anthropogenic activities have endangered these waters, little is known about their water quality or biodiversity. We monitored five springs...

Sample collection and culture Aquatic plant samples were collected from habitats across the USA and a sediment sample from Australia (Tables S1.1, S1.2). Limnias melicerta and L. ceratophylli were identified and isolated from rehydrated sediments or by removing a piece of vegetation to which they were attached. Species identification was based on t...

Although the most widely used key to the Rotifera subsumes six species of the sessile genus Limnias within two species groups (L. ceratophylli and L. melicerta), the original descriptions of these forms are sufficiently different to recognize them as distinct entities. We used these descriptions and all available literature on these species to deve...

While separated by large expanses of dry terrain unsuitable for aquatic biota, aridland waters possess high biodiversity. How aquatic micrometazoans disperse to, and colonize, these isolated ephemeral habitats are not well understood. We used a multi-faceted approach including wind tunnel and rehydration experiments, and next-generation sequencing...

Determining genetic structure is fundamental to our understanding of how populations adapt and evolve. Increasingly cryptic species complexes are being discovered in zooplankton, including rotifers. We used three molecular markers to investigate partitioning of genetic diversity within five populations of the cosmopolitan rotifer Euchlanis dilatata...

Based on material from aquatic habitats in the northern Chihuahuan Desert and a literature review, we present an account on the occurrence of genus Rhinoglena in North America. Two new species are described, and the presence of Rhinoglena frontalis in the USA is confirmed. Of the two new species, R. texana n. sp. is a close relative of R. frontalis...

Understanding patterns and processes in biological diversity is a critical task given current and rapid environmental change. Such knowledge is even more essential when the taxa under consideration are important ecological and evolutionary models. One of these cases is the monogonont rotifer cryptic species complex Brachionus plicatilis, which is b...

We present a survey of the literature documenting sexuality in monogonont rotifers, including reports of diapausing embryos (DEs), males, and/or hatchlings from dry sediments. Of 30 families, 27 possess species with documented occurrences of sex. Information on DEs is lacking in 41 genera. Of ~300 species with evidence of sexuality (~20% of ~1500 m...

Diaphanosoma turkanae sp. nov. is described from Lake Turkana (Kenya, East Africa). This species is the second Afrotropical endemic in the order Ctenopoda. It is characterized by a distinctive feature, the presence of an unusually small number of setae on the upper two-segmented antennal branch (exopodite); the proximal segment of the branch always...

We provide descriptions of the sexual reproductive biology of 12 species of rotifers from seven families and seven genera: Brachionus angularis, B. araceliae, B. ibericus, B. quadridentatus (Brachionidae); Cephalodella catellina (Notommatidae); Collotheca ornata (Collothecidae); Epiphanes brachionus (Epiphanidae), Filinia novaezealandiae (Trochosph...

Members of the sessile rotifer species Cupelopagis vorax are unusual ambush predators that live permanently attached to submerged freshwater plants. Previous light microscopical research has revealed several uncommon features in this species including a stellate-patterned integument and an expansive foregut region called the proventriculus. In this...

The second volume in this landmark series includes an introductory chapter followed by 15 taxonomically specific chapters with identification keys to Nearctic freshwater invertebrates (protozoa through arthropods). Other than the second chapter's treatment of the diverse, multi-phyla array of protozoa (ciliates, flagellates, and amoebas), each of t...

Jaws have evolved numerous times in the animal kingdom and they display a wide variety of structural, compositional, and functional characteristics that reflect their polyphyletic origins. Among soft-bodied invertebrates, jaws are known from annelids, chaetognaths, flatworms, gnathostomulids, micrognathozoans, mollusks, rotifers, and several ecdyso...

PPCPs have been reported in surface waters around the world. The continuous input of these pollutants into freshwaters and their potential effects on aquatic life are of increasing concern. The rotifer Plationus patulus, a basal member of riverine food webs, was used to test acute and chronic toxicity of four PPCPs (acetamidophenol, caffeine, fluox...

Background/Question/Methods Hydrochory is the typical mode of dispersal for aquatic invertebrates in interconnected watersheds. However, in highly isolated desert playas, wind may be the primary mechanism, facilitating colonization and gene flow among these populations. In the North American desert southwest, dust blows west-to-east, carrying def...

The freshwater littoral comprises a mosaic of habitats structured at several scales by a combination of hydrophyte architecture and physiology. Within this complex environment littoral invertebrates should distribute themselves to maximize fitness: that is, for sessile animals selection of permanent substrata is critical, while distribution of moti...

While ubiquitous, temporary waters vary greatly in geographic distribution, origin, size, connectivity, hydroperiod, and biological composition. However, all terminate as active habitats, transitioning into either dryness or ice, only to be restored when conditions improve. Hydroperiod in some temporary habitats is cyclical and predictable, while i...

In many aquatic invertebrates including monogonont rotifers, sex provides genetic variation and dormant stages that allows dispersal in time and space. While the reproductive biology of some solitary monogonont rotifer species is known, little is known concerning mating behaviors in colonial rotifers. Coloniality poses unique challenges to the typi...

Urbanization can have significant ecological effects on natural populations, including habitat fragmentation through increased road density. One road effect of concern is their potential to limit wildlife movements. Roads may disrupt gene flow, causing increased inbreeding, decreased genetic diversity, and increased genetic differentiation. In this...

Pharmaceuticals and Personal Care Products (PPCPs) are chemicals of emerging concern that are present in our nation’s waterways. The Rio Grande is important to the United States and Mexico since it’s a major source of drinking and irrigation water. The river receives pollutants from industrial, urban and agricultural returns that potentially affect...

Background/Question/Methods Urbanization can have significant ecological effects on natural populations, including habitat fragmentation through increased road density. The effect of roads is of concern due to their potential impacts on wildlife movements. Roads may increase mortality rates, leading to inbreeding and decreased genetic diversity....

Background/Question/Methods Pharmaceutical and Personal Care Products (PPCPs) are chemicals of emerging concern that have been detected in many of our nation’s waterways. The Rio Grande is an important system to the United States and to Mexico, including the El Paso/Ciudad Juárez metroplex where it serves as the main source of drinking and irriga...

Impacts of water quality on the genetic structure of aquatic organisms have not been well characterized. Unfavorable conditions may result in loss of species diversity and/ or select for tolerant genotypes. With the loss of genetic diversity populations aren’t able to adapt to changes in their environments. We investigated whether aquatic pollutant...

Background/Question/Methods A current debate in ecology centers on the idea that microscopic organisms have global dispersal capabilities but nature selects which species are represented locally (the Baas-Becking Hypothesis). These organisms often play important roles in nutrient cycling and food webs of aquatic communities. Recently, with the us...

Background/Question/Methods Pharmaceutical and Personal Care Products (PPCPs) are chemicals of emerging concern that have been detected in many of our nation’s waterways. The Rio Grande is the main source for drinking and irrigation water to many parts of the United States and to Mexico, especially the El Paso/Ciudad Juárez metroplex. The river r...

Background/Question/Methods Compared to tropical and temperate environments, life for the zooplankton in aridlands seems precarious: vast tracts of dryness separate these waters and the risk of drought is continual, even in permanent habitats (e.g., springs, rivers, reservoirs). However, in temporary waters (e.g., playas, rock pools) probability...

The Zooplankton fauna of freshwater systems of the Chihuahuan Desert was surveyed 2005-2008. Samples were obtained from habitats including natural lakes, ephemeral waters, springs, and reservoirs. Copepods were sorted and identified to species. Including previous surveys, a total of 38 species occur in the Chihuahuan Desert, the checklist includes...

1. Many aquatic species usually considered to be ‘cosmopolitan’ have been identified as cryptic species complexes, based on deep genetic differentiation. However, reproductive isolation among sibling cryptic species has rarely been studied, and interspecific hybridisation is common in some taxa. 2. We investigated isolation mechanisms and possible...

Mining and industrial development have caused metal contamination in aquatic systems. Rotifers have been used as indicators of environment health due to their ubiquity and life characteristics. Effects of bi-metal mixtures on rotifers were evaluated to determine significant variations on population growth, reproductive mode and developmental parame...

Globally heavy metal contamination is one of the major classes of environmental pollutants. A primary mechanism in the regulation of many cellular processes, including attachment, sequestration and remediation of heavy metals, is protein phosphorylation. We use a model invertebrate, Rotifera, to investigate cellular responses to metals and investig...

Two new species of the freshwater copepod genus Eucyclops are described from two sites in the Chihuahuan Desert (CHD), which includes parts of northern Mexico and southern United States. Eucyclops cuatrocienegas sp. nov. is distinguished by having a short inner spiniform seta on the fifth leg, relatively short caudal rami, and a partially naked spi...

Two new species of the freshwater copepod genus Eucyclops are described from two sites in the Chihuahuan Desert (CHD), which includes parts of northern Mexico and southern United States. Eucyclops cuatrocienegas sp. nov. is distinguished by having a short inner spiniform seta on the fifth leg, relatively short caudal rami, and a partially naked spi...

Background/Question/Methods . The Chihuahuan Desert is a unique region with high biodiversity. There is a high degree endemism of freshwater biota, but relatively few studies have been focused on zooplankton. Bdelloid rotifers are one component of these ecosystems and often dominate very temporary habitats. Bdelloids are usually assumed to be cosmo...

Background/Question/Methods . Heavy metal contaminants are known to negatively impact ecosystem function and structure. Previous studies in the Northern Chihuahuan Desert have shown that the area has been subjected to considerable amounts of heavy metal contamination likely due to copper refining activities. UTEP SEEDS students gave on-campus a...

FIGURE 1. Eucyclops cuatrocienegas sp. nov., adult female holotype from Cuatro Ciénegas, Coahuila, northern Mexico. A) habitus, dorsal view; B) antennule; C) caudal rami, dorsal view; D) same, ventral view. Scale bars A = 100 μm, B – D = 50 μm.

FIGURE 3. Eucyclops cuatrocienegas sp. nov., adult female holotype from Cuatro Ciénegas, Coahuila, northern Mexico. A) leg 1 with coxal plate (separate), frontal view; B) leg 2 with coxal plate, frontal; C) leg 3 with coxal plate, frontal; D) leg 4 with coxal plate, frontal; E) leg 5. Scale bars A – E = 50 μm.

FIGURE 5. Eucyclops pseudoensifer Dussart, 1984, adult female paratype (MNHN- 2547) from Laguna Mucubajì, Venezuela. A) antennule; B) leg 5; C) caudal rami, ventral view; D) same, dorsal view; holotype female, E) right caudal rami, ventral view. E from D. Defaye’s drawing of the holotype specimen (in litt.). Scale bars A = 50 μm, B = 25 μm, C – E =...

FIGURE 10. Eucyclops chihuahuensis sp. nov., adult female holotype from Presa Chihuahua, northern Mexico. A) leg 1; B) leg 2; C) leg 2; D) leg 4; E) coxal plate of leg 1; F) coxal plate of leg 1; G) coxal plate of leg 3; H) coxal plate of leg 4. Scale bars A – G = 50 μm. All appendages shown in frontal view.

FIGURE 4. Eucyclops cuatrocienegas sp. nov., adult male allotype from Cuatro Ciénegas, Coahuila, northern Mexico. A) habitus, dorsal view; B) fifth pedigerous and genital somites, ventral; C) right caudal ramus, dorsal view; D) inner terminal caudal seta showing ornamentation pattern. E) antennule. Scale bars A = 100 μm, B – E = 60 μm.

FIGURE 9. Eucyclops chihuahuensis sp. nov., adult female holotype from Presa Chihuahua, northern Mexico. A) habitus, dorsal view; B) antennule; C) antenna; D) caudal rami and anal somite, ventral view; E) genital double and fifth pedigerous somites, ventral view. Scale bars A = 100 μm, B – D = 50 μm.

FIGURE 2. Eucyclops cuatrocienegas sp. nov., adult female holotype from Cuatro Ciénegas, Coahuila, northern Mexico. A) fifth pedigerous and genital double somites, ventral view; B) mandible with palp; C) detail of gnathal blade; D) antenna; E) maxillule; F) maxilla; G) maxilliped. Scale bars A – G = 50 μm.

FIGURE 6. Eucyclops pseudoensifer Dussart, 1984, adult female paratype (MNHN- 2547) from Laguna Mucubajì, Venezuela. A) antenna; B) leg 1; C) leg 2; D) leg 3. Scale bars A – D = 50 μm.

FIGURE 7. Eucyclops pseudoensifer Dussart, 1984, A adult female paratype (MNHN- 2547) from Laguna Mucubajì, Venezuela. B-D from D. Defaye’s drawings of the holotype specimen (MNHN-Cp 663) (in litt.). A) leg 4; B) leg 1, coupler and inner margin of coxa and basipod; C) leg 4, ornamentation of coupler; D) leg 3, same. Scale bars A = 50 μm, B – D = 25...

FIGURE 8. Eucyclops pseudoensifer Dussart, 1984, adult male paratype (MNHN- 2548) from Laguna Mucubajì, Venezuela. A) leg 3; B) leg 4; C) caudal rami, dorsal view; D) geniculate antennule. Scale bars A – D = 50 μm.

For decades, the coastal-estuarine copepod, Eurytemora affinis (Poppe, 1880) was considered a cosmopolitan species. Recent studies have demonstrated that it represents a species complex with static morphology but with genetically recognizable forms clustered in defined geographical patterns. In North America, this species is widely distributed in c...

In spite of considerable efforts over past decades we still know relatively little regarding the biogeography of rotifers of inland waters in México. To help rectify this we undertook an extensive survey of the rotifer fauna of 48 water bodies in the Chihuahuan Desert of México. Of the sites surveyed, 21 had salinities >or= 2000 microS cm-1 and in...