Jeffrey W Shultz

University of Maryland, College Park | UMD, UMCP, University of Maryland College Park · Department of Entomology

Organismal biology (OrgBio) comprises the diversity, structures, and functions of all organisms from bacteria to humans. Arguably, OrgBio is often the most poorly taught and least conceptually rigorous section of the introductory biology sequence offered at most U.S. institutions of higher education. This article reports on the successful implement...

Many arachnids use internal hemolymph pressure to actuate extension in their leg joints. The inherent large foot displacement‐to‐body length ratio that arachnids can achieve through hydraulics relative to muscle‐based actuators is both energy and volumetrically efficient. Until recent advances in nano/microscale 3D printing with two‐photon polymeri...

In its first twenty years of existence Zootaxa has been widely utilized among researchers of Opiliones, mainly those coming from Latin American countries, principally Brazil. During 2003-2020, a total of 141 papers on Opiliones were published in Zootaxa (no papers were published on Opiliones in the first two years, 2001-2002). The journal has great...

Chelicerata is the group of arthropods that includes extant marine sea spiders (Pycnogonida) and horseshoe crabs (Xiphosurida), mainly terrestrial Arachnida (spiders, mites, scorpions, etc.), and extinct fossil groups, including sea scorpions. Most chelicerates have two body regions, a prosoma bearing feeding and leg‐like appendages and an opisthos...

Harvestmen (Arachnida: Opiliones) were among the earliest terrestrial arthropods but their unmineralized exoskeletons are scarce and often fragmentary as fossils (Palencia et al. 2019). Consequently, the discovery and interpretations of fossil harvestmen from the early Palaeozoic can have disproportionate effects on the understanding of evolution i...

The taxonomic diversity of the Opiliones fauna of Canada is reviewed and summarised. At present, 36 native and seven non-native species have been documented in Canada using traditional morphological taxonomy, although more than 20 species may remain undiscovered based on species diversity in the adjacent United States and evidence from DNA barcodin...

The terrestrial isopod fauna of Maryland is inferred using the taxonomic literature, internet-based citizen science projects, and original collecting. Twenty-two species are either known or are likely to occur in the state. This includes 17 mostly-European adventive species that comprise the vast majority of records. Of the five expected native spe...

A taxonomic key, diagnoses, and geographic distributions are provided for the 24 species of harvestmen that are known from or are likely to occur in Maryland. Twenty species are documented, with records of Caddo agilis, Phalangium opilio, Odiellus pictus, Leiobunum flavum, and Vonones sayi published for the first time. Four additional species- Acro...

A new species of leiobunine harvestman from the Chiricahua Mountains of Arizona is described. The species lacks pro- and retrolateral submarginal rows of coxal denticles, a feature often considered diagnostic for the polyphyletic Nelima, and has greatly reduced ventral dentition on the palpal claw, as in the monotypic Leuronychus. In most other res...

A year-long continuous pitfall trapping program in 8 habitats at the Savannah River Site on South Carolina's coastal plain yielded over 4200 individual Opiliones, and the resulting data set provides a fine-grained description of Opiliones faunistics, habitat distribution, and phenology in southeastern North America, where Opiliones biology has been...

The morphology of arthropod intromittent organs evolves rapidly and is often species specific, phenomena widely attributed to sexual selection. Similar patterns in biomechanical properties may also exist, but practical challenges in manipulating small structures and measuring minute forces has impeded experimental biomechanical analysis. Here we de...

Diversity in reproductive structures is frequently explained by selection acting at individual to generational timescales, but interspecific differences predicted by such models (e.g., female choice or sexual conflict) are often untestable in a phylogenetic framework. An alternative approach focuses on clade- or function-specific hypotheses that pr...

Explaining the rapid, species-specific diversification of reproductive structures and behaviors is a long-standing goal of evolutionary biology, with recent research tending to attribute reproductive phenotypes to the evolutionary mechanisms of female mate choice or intersexual conflict. Progress in understanding these and other possible mechanisms...

Taxon sampling for BEAST v1.7.1 phylogenetic reconstruction and reproductive trait evaluation. Accession numbers are for the GenBank sequence repository; numbers GQ870643–GQ870668 and GQ872152–GQ872185 are derived from [74]. Columns 5 and 6 include relevant papers on species morphology [53]–[54]; [75]–[78] and/or numbers of male and female specimen...

Three caddid harvestmen are known from eastern North America— Caddo agilis Banks, C. pepperella Shear and Acropsopilio boopis (Crosby) (Fig. 1). All also occur in Japan (Suzuki 1976; Shultz & Regier 2007), and all are apparently parthenogenetic, although a few male specimens of C. agilis are known (Gruber 1974, Suzuki & Tsurusaki 1983). The three s...

Even though Hadrobunus grandis (Say 1821) is the type species of Hadrobunus, its identity has been uncertain since its original description. The type specimens were collected in coastal Georgia and/or northeastern Florida during the winter of 1817–1818, not from the mid-Atlantic Region (e.g., Virginia, Maryland) as assumed by some authors. This err...

Next-generation sequencing technologies are rapidly transforming molecular systematic studies of non-model animal taxa. The arachnid order Opiliones (commonly known as "harvestmen") includes more than 6,400 described species placed into four well-supported lineages (suborders). Fossil plus molecular clock evidence indicates that these lineages were...

Individual gene matrices. (DOCX)

Results of analyses of unpartitioned nucleotide matrices with third position sites removed. (TIF)

Gene ontologies. (DOCX)

Results from gene ontology analysis. (DOCX)

Results of alternative clock analyses. (DOCX)

Summary information for individual gene matrices (e.g., gene identities, nucleotide alignment lengths, PI values, average pairwise divergence values, taxon composition, etc.). (XLSX)

Next-generation sequencing technologies are rapidly transforming molecular systematic studies of non-model animal taxa. The arachnid order Opiliones (commonly known as “harvestmen”) includes more than 6,400 described species placed into four well-supported lineages (suborders). Fossil plus molecular clock evidence indicates that these lineages were...

Phylogenetic relationships within the Sclerosomatidae, the largest family of harvestmen, are explored using molecular data from four nuclear genes (28S and 18S rRNA, Histone 3 and Elongation factor-1α) and two mitochondrial gene regions (COI-COII, 16S and 12S rRNA). The taxon sample includes representative species from all families in Phalangioidea...

Phylogenetic relationships among the leiobunine harvestmen or "daddy-longlegs" of eastern North America (Leiobunum, Hadrobunus, Eumesosoma) are poorly known, and systematic knowledge of the group has been limited largely to species descriptions and proposed species groups. Here we obtained mitochondrial (NADH1, 16S and 12S rDNA) and nuclear (28S rD...

The Leiobunum calcar species-group is erected to accommodate four species of North American harvestmen, namely, L. nigropalpi (Wood 1868), L. euserratipalpe new species, L. calcar (Wood 1868) and L. hoffmani new species. The group is characterized by several sexually dimorphic characters, including an elongate penis lacking subterminal sacs, base o...

A new genus and species of synziphosurine (Chelicerata) is described from the Silurian (Wenlock) Scotch Grove Formation Konservat-Lagerstätte in Clinton County, Iowa. Camanchia grovensis n. gen. n. sp. is characterized by a sub-triangular carapace, ten opisthosomal segments divided into a preabdomen of seven and a postabdomen of three, and a tuberc...

Species-specific variation in reproductive structures is a pervasive theme in arthropod evolution, but researchers differ on the mechanism of sexual selection that produces and maintains genitalic diversity. Here we reconstruct the phylogenetic relationships of North American leiobunine harvestmen using molecular data to determine the direction and...

A new species of harvestman from the endemic North American genus Hadrobunus Banks, 1900 is described. The species, H. fusiformis, differs substantially from known USA species in both somatic and genital morphology, but the male resembles that of H. knighti from northern Mexico in having a long, narrow penis and posteriorly tapered opisthosoma.

Aquatic nymphs of the mayfly Centroptilum triangulifer produce ventilatory flow using a serial array of seven abdominal gill pairs that operates across a Reynolds numbers (Re) range from 2 to 22 during ontogeny. Net flow in small animals is directed ventrally and essentially parallel to the stroke plane (i.e. rowing), but net flow in large animals...

Although metazoan body plans are remarkably diverse, the structure and function of many embryonic regulatory genes are conserved because large changes would be detrimental to development. However, the fushi tarazu (ftz) gene has changed dramatically during arthropod evolution from Hox-like to a pair-rule segmentation gene in Drosophila. Changes in...

Our focus was to design harvestmen-specific PCR primers to target both introns and exons of the nuclear protein-coding gene Elongation Factor -1 alpha (EF-1α). We tested this primer set on ten genera representing all primary lineages of Opiliones, with sets of close phylogenetic relatives (i.e., sets of several congeners) included to specifically a...

The remarkable antiquity, diversity and ecological significance of arthropods have inspired numerous attempts to resolve their deep phylogenetic history, but the results of two decades of intensive molecular phylogenetics have been mixed. The discovery that terrestrial insects (Hexapoda) are more closely related to aquatic Crustacea than to the ter...

Mayfly nymphs are aquatic insects, many of which can generate ventilation currents by beating two linear arrays of external plate-like gills. The oscillation Reynolds number associated with the gill motion changes with animal size, varying from Re ˜ 2 to 50 depending on age and species. Thus mayflies provide a novel system model for studying ontoge...

Comparative studies encompassing a wide range of aquatic animals have shown that rowing is exclusively used at low Reynolds numbers (Re < 1), whereas flapping is predominantly used at Re > 100, although few studies have been undertaken to document the transition in individual species that traverse the intermediate Re regime using a single set of ap...

The harvestmen Caddo agilis Banks 1892 and C. pepperella Shear 1975 (Caddidae, Caddinae) share a disjunct distribution in eastern Asia and eastern North America that has been attributed to either recent (Pleistocene) evolution of a C. pepperella morph from C. agilis in each region or to a pre-glacial separation within each of two established specie...

Phylogenetic relationships among basal hexapod lineages were investigated using molecular sequence data derived from three nuclear genes: elongation factor-1α, RNA polymerase II, and elongation factor-2. Nucleotide and amino acids from 12 hexapods and 22 crustacean outgroups were analyzed using maximum parsimony and maximum likelihood methods. The...

Two nominal species of harvestmen from eastern North America, Leiobunum verrucosum and L. nigripes, are generally distinguished by color patterns. However, laboratory-reared individuals and sequential sampling in the field clearly show that adult individuals change from the “verrucosum” pattern to the “nigripes” pattern during normal maturation. Sp...

The first species of the genus Austropsopilio is described from South America. The species, A. sudamericanus, closely resembles those from Australia and Tasmania but lacks the elongate ocular tubercle previously regarded as diagnostic for the genus. Problems in the taxonomy of the genus are discussed. RESUMEN Se reporta por primera vez la presencia...

This paper describes the first South American species of Hesperopilio Shear 1996, a genus previously known from a single species, H. mainae Shear 1996, from Western Australia. The new species is known from a single adult female and is one of the largest and most colorful species of the superfamily Caddoidea. The generic diagnosis of Hesperopilio is...

Recent phylogenetic studies of Opiliones have shown that Cyphophthalmi and Phalangida (= Palpatores + Laniatores) are sister groups, but higher relationships within Phalangida remain controversial. Current debate focuses on whether Palpatores (= Caddoidea + Phalangioidea + Ischyropsalidoidea + Troguloidea) is monophyletic or paraphyletic, with Isch...

Due to their widespread use as model systems and their reputation as living fossils, horseshoe crabs (Xiphosura) have been studied intensively by physiologists and paleontologists. The close phylogenetic relationship between horseshoe crabs and arachnids might also have been expected to inspire studies of xiphosurans by comparative arachnologists,...

This study attempts to resolve relationships among and within the four basal arthropod lineages (Pancrustacea, Myriapoda, Euchelicerata, Pycnogonida) and to assess the widespread expectation that remaining phylogenetic problems will yield to increasing amounts of sequence data. Sixty-eight regions of 62 protein-coding nuclear genes (approximately 4...

Nucleotide and inferred amino acid sequences from two nuclear protein-encoding genes, elongation factor-a and RNA polymerase II, were obtained from 34 myriapods and 14 other arthropods to determine phylogenetic relationships among and within the myriapod classes. Phylogenetic analyses using maximum parsimony and maximum likelihood methods recovered...

The morphological diversity of locomotor appendages in Arachnida is surveyed lo reconstruct phylogenetic relationships and discover evolutionary trends in form and function. The appendicular skeleton and musculature of representatives from the ten living arachnid orders ate described, and a system of homology is proposed. Character polarities are e...

Skeletal muscles in the whipspider Phrynus longipes are surveyed and compared with those of other chelicerates to clarify the evolutionary morphology and phylogenetic relationships of the arachnids. Representatives of 115 muscle groups are described and illustrated, and their possible functions are proposed. Principal results of this analysis inclu...

1Previous attempts to explain the evolution of spider silk have relied heavily on conjecture. The formulation of testable historical hypotheses to replace such speculation is discussed.2The importance of phylogenetic reconstructions and other historical hypotheses for use in generating and testing hypotheses concerning the evolution of specific ada...

Mayfly nymphs are aquatic insects which alter behavior and metabolism to accommodate changes in ambient dissolved oxygen. Many species can generate a ventilation current to compensate for low oxygen levels by beating two linear arrays of plate-like gills that line the lateral edge of the abdomen. The oscillation Reynolds number associated with the...

Morphological evidence for resolving relationships among arachnid orders was surveyed and assembled in a matrix comprising 59 euchelicerate genera (41 extant, 18 fossil) and 202 binary and unordered multistate characters. Parsimony analysis of extant genera recovered a monophyletic Arachnida with the topology (Palpigradi (Acaromorpha (Tetrapulmonat...

Skeletomuscular anatomy of the scorpion prosoma is examined in an attempt to explain the evolution of two endoskeletal features, a muscular diaphragm dividing the prosoma and opisthosoma and cuticular epistomal entapophyses with a uniquely complex arrangement of muscles, tendons and ligaments. Both structures appear to be derived from modifications...

Mayfly nymphs are entirely aquatic and must alter behavior and metabolism to accommodate changes in ambient dissolved oxygen levels. Many species can generate a ventilation current to compensate for low oxygen levels by beating two linear arrays of plate-like gills that line the lateral edge of the abdomen. The characteristic Reynolds number associ...

The Ftz-F1 (NR5A) family of nuclear receptors (NRs) is a large group of proteins involved in a wide range of biological processes. This is an ancient family that is currently represented broadly throughout the animal kingdom. Ftz-F1 family NRs can bind to DNA as monomers; in addition to the zinc finger DNA-binding motifs, these proteins contain a C...

Mayfly nymphs have an entirely aquatic life stage in which they frequently inhabit stagnant water. Nymphs have the capability to generate a ventilation current to compensate for the low oxygen level of the water by beating two linear arrays of plate-like gills that typically line the lateral edge of the abdomen. The characteristic Reynolds number a...

Coding sequences (5,334 nt total) from elongation factor-1, elongation factor-2, and the largest subunit of RNA polymerase II were determined for 6 species of Tardigrada, 2 of Arthropoda, and 2 of Onychophora. Parsimony and likelihood analyses of nucleotides and amino acids yielded strong support for Tardigrada and all internal nodes (i.e., 100% bo...

A remarkable specimen of Mesolimulus from the Upper Jurassic (Kimmeridgian) of Nusplingen, Germany, preserves the musculature of the prosoma and associated microbes in three dimensions in calcium phosphate (apatite). The musculature of Mesolimulus conforms closely to that of modern horseshoe crabs. Associated with the muscles are patches of mineral...

Recent molecular analyses indicate that crustaceans and hexapods form a clade (Pancrustacea or Tetraconata), but relationships among its constituent lineages, including monophyly of crustaceans, are controversial. Our phylogenetic analysis of three protein-coding nuclear genes from 62 arthropods and lobopods (Onychophora and Tardigrada) demonstrate...

We assessed the ability of three nuclear protein-encoding genes-elongation factor-1alpha (EF-1alpha), RNA polymerase II (Pol II), and elongation factor-2 (EF-2)-from 59 myriapod and 12 non-myriapod species to resolve phylogenetic relationships among myriapod classes and orders. In a previous study using EF-1alpha and Pol II (2134 nt combined) from...

Relationships among the ecdysozoans, or molting animals, have been difficult to resolve. Here, we use nearly complete 28S+18S ribosomal RNA gene sequences to estimate the relations of 35 ecdysozoan taxa, including newly obtained 28S sequences from 25 of these. The tree-building algorithms were likelihood-based Bayesian inference and minimum-evoluti...

Certain joints in the pedipalps of scorpions and sun-spiders lack extensor muscles but have elastic transarticular sclerites that store energy during flexion and return energy as elastic recoil during extension. This Study quantifies the extension torque contributed by elastic recoil and hydraulic pressure in the chela (tibia-tarsus) and femur-pate...

Coding sequences (5,334 nt total) from elongation factor-1alpha, elongation factor-2, and the largest subunit of RNA polymerase II were determined for 6 species of Tardigrada, 2 of Arthropoda, and 2 of Onychophora. Parsimony and likelihood analyses of nucleotides and amino acids yielded strong support for Tardigrada and all internal nodes (i.e., 10...

Certain leg joints in arachnids lack extensor muscles and have elastically deformable transarticular sclerites spanning their arthrodial membranes, an arrangement consistent with a model in which flexor muscles load transarticular sclerites during flexion and energy from elastic recoil is used for extension. This study quantifies the potential cont...

Robust resolution of controversial higher-level groupings within Arthropoda requires additional sources of characters. Toward this end, elongation factor-2 sequences (1899 nucleotides) were generated from 17 arthropod taxa (5 chelicerates, 6 crustaceans, 3 hexapods, 3 myriapods) plus an onychophoran and a tardigrade as outgroups. Likelihood and par...

Chelicerata is the group of arthropods that includes the marine sea-spiders and horseshoe crabs and the terrestrial arachnids (spiders, mites, scorpions and their relatives). They have two main body regions, and the arachnids typically have eight walking legs. They are covered by a jointed exoskeleton and grow by periodic moulting. Chelicerates are...

Recent phylogenetic analyses using molecular data suggest that hexapods are more closely related to crustaceans than to myriapods, a result that conflicts with long-held morphology-based hypotheses. Here we contribute additional information to this debate by conducting phylogenetic analyses on two nuclear protein-encoding genes, elongation factor-1...

Skeletal muscles of the North American harvestman Leiobunum aldrichi are exhaustively surveyed and compared with other chelicerates to clarify the evolutionary morphology and phylogenetic relationships of arachnids. Representatives of 104 muscle groups are described and illustrated, and their possible functions are proposed. Comparisons of the feed...

Skeletal muscles in the whipspider Phrynus longipes are sun-eyed and compared with those of other chelicerates to clarify the evolutionary morphology and phylogenetic relationships of the arachnids. Representatives of 115 muscle groups are described and illustrated, and their possible functions are proposed. Principal results of this analysis inclu...

SYNOPSIS. Accurate phylogenetic reconstruction requires character systems that have evolved fast enough to have kept pace with cladogenesis but slowly enough to have conveyed the resulting phylogenetic signal to the present. Because strati-graphic evidence suggests that basal arthropod lineages arose rapidly during an ancient (Cambrian) phylogeneti...

Accurate phylogenetic reconstruction requires character systems that have evolved fast enough to have kept pace with cladogenesis but slowly enough to have conveyed the resulting phylogenetic signal to the present. Because stratigraphic evidence suggests that basal arthropod lineages arose rapidly during an ancient (Cambrian) phylogenetic radiation...

The arachnid order Opiliones has typically been divided into three suborders (Cyphophthalmi, Laniatores and Palpatores), but this system has been challenged in recent years. Based on scenarios of genitalic evolution, Martens and coworkers have argued that certain lineages within Palpatores are more closely related to Cyphophthalmi than to other pal...

A phylogeny of the arthropods was inferred from analyses of amino acid sequences derived from the nuclear genes encoding elongation factor-1 alpha and the largest subunit of RNA polymerase II using maximum-parsimony, neighbor-joining, and maximum-likelihood methods. Analyses of elongation factor-1 alpha from 17 arthropods and 4 outgroup taxa recove...

This paper reports results from a preliminary molecular systematic analysis of the chilopod orders. Nucleotide sequences from a slowly evolving nuclear protein-coding gene, elongation factor-1 alpha, were obtained from five centipedes representing the four principal chilopod orders and from five outgroup taxa. Maximum-parsimony analysis of inferred...