Darryl L. Felder

Ontogenetic Change in Digestive Enzyme Activity of Larval and Postlarval White Shrimp Penaeus setiferus (Crustacea, Decapoda, Penaeidae)

Whole specimens of developmental stages of Penaeus setiferus (Linnaeus, 1767) were homogenized and assayed for activities of digestive enzymes. In all developmental stages, activities were present for trypsin, carboxypeptidase A and B, amylase, and non-specific esterase; none for pepsin or lipase were detected. Activities assayed with substrates for chymotrypsin and aminopeptidase are not apparently due to the presence of these enzymes in the gut. Peak activities for all enzymes occurred during late zoeal or early mysis larval stages; low activities occurred at metamorphosis. During postlarval development, amylase activity increased steadily (by a tenfold increase over five weeks), whereas most other enzyme activities were relatively constant until the fifth week of postlarval development. Although it alters enzyme activity, diet does not appear to be the primary effector of ontogenetic change in digestive enzyme activity. Instead, ontogenetic change in digestive enzyme activity may reflect either a developmentally cued change in enzyme synthesis, or a secondary effect of change in the function and relative size of the midgut during its differentiation.

GLYPTOGRAPSIDAE, A NEW BRACHYURAN FAMILY FROM CENTRAL AMERICA: LARVAL AND ADULT MORPHOLOGY, AND A MOLECULAR PHYLOGENY OF THE GRAPSOIDEA

Abstract During an ongoing systematic revision of the Decapoda Grapsoidea (here defined as including the families Gecarcinidae, Grapsidae s. str., Plagusiidae, Sesarmidae, and Varunidae; see Schubart et al., 2000a), it became evident that adult and larval morphology of two Central American genera, Glyptograpsus and Platychirograpsus, differs greatly from that of all other genera within this superfamily. Several important morphological characters are shared by these two genera and represent synapomorphies when compared to the other grapsoids. Both of these genera lack a pleurobranch on the sixth thoracic segment. Adult males of Glyptograpsus and Platychirograpsus are all strikingly heterochelous with the major chela being conspicuously flattened anteriorly and showing a subproximal articulation with the carpus. The distal portion of the male gonopod is uncinate, with a narrowed, elongate terminus. The anteriormost portion of the sternum consists of a narrow, fused sternite terminated in a distinctly flanged tip inserted between the mouth appendages. The male abdomen exhibits immobility in the joints between segments 3 to 5 and very limited mobility in the joint between segments 1 and 2. Zoeae of the two genera show a 1,2 setation pattern on the maxillar endopod. A molecular phylogeny of the Grapsoidea, based on 16S mtDNA and including type genera of the five recognized families, confirms that the species of Glyptograpsus and Platychirograpsus together form a well-defined monophyletic unit that is distinct from all other taxa within the Grapsoidea. We therefore describe a new family, the Glyptograpsidae, to accommodate these two genera of crabs.

Decapod crustacean phylogenetics

Overviews of Decapod Phylogeny On the Origin of Decapoda, F. R. Schram Decapod Phylogenetics and Molecular Evolution, A. Toon, M. Finley, J. Staples, and K. A. Crandall Development, Genes, and Decapod Evolution, G. Scholtz, A. Abzhanov, F. Alwes, C. Biffis, and J. Pint Mitochondrial DNA and Decapod Phylogenies: The Importance of Pseudogenes and Primer Optimization, C. D. Schubart Phylogenetic Inference Using Molecular Data, F. Palero and K. A. Crandall Decapod Phylogeny: What Can Protein-Coding Genes Tell Us?, K. H. Chu, L. M. Tsang, K. Y. Ma1, T.-Y. Chan, and P. K. L. Ng Spermatozoal Morphology and its Bearing On Decapod Phylogeny, C. Tudge Evolution of Mating Systems in Decapod Crustaceans, A. Asakura A ShrimpaEURO (TM)s Eye View of Evolution: How Useful are Visual Characters in Decapod Phylogenetics?, M. L. Porter and T. W. Cronin Crustacean Parasites as Phylogenetic Indicators in Decapod Evolution, C. C. Boyko and J. D. Williams The Bearing of Larval Morphology on Brachyuran Phylogeny, P. F. Clark Advances in our Knowledge of Shrimp-like Decapods Evolution and Radiation of Shrimp-like Decapods: an Overview, C. H. J. M. Fransen and S. De Grave A Preliminary Phylogenetic Analysis of the Dendrobranchiata based on Morphological Characters, C. Tavares, C. Serejo and J. W. Martin Phylogeny of the Infraorder Caridea based on Mitochondrial and Nuclear Genes (Crustacea: Decapoda), H. D. Bracken, S. De Grave, and D. L. Felder Advances in our Knowledge of Thalassinoid and Lobsterlike Groups Molecular Phylogeny of the Thalassinidea based on Nuclear and Mitochondrial Genes, R. Robles, C. C. Tudge, P. C. Dworschak, G. C. B. Poore, and D. L. Felder Molecular Phylogeny of the Family Callianassidae based on Preliminary Analyses of Two Mitochondrial Genes, D. L. Felder and R. Robles The Timing of the Diversification of the Freshwater Crayfishes, J. Breinholt, M. PA (c)rez-Losada, and K. A. Crandall Phylogeny of Marine Clawed Lobster Families Nephropidae Dana, 1852, and Thaumastochelidae Bate, 1888, based on Mitochondrial Genes, D. Tshudy, R. Robles, T.-Y. Chan, K. C. Ho, K. H. Chu, S. T. Ahyong, and D. L. Felder The Polychelidan Lobsters: Phylogeny and Systematics (Polychelida: Polychelidae), S. T. Ahyong Advances in our Knowledge of the Anomura Anomuran Phylogeny: New Insights from Molecular Data, S. T. Ahyong, K. E. Schnabel, and E. W. Maas Advances in our Knowledge of the Brachyura Is the Brachyura Podotremata a Monophyletic Group?, G. Scholtz and C. L. Mclay Assessing the Contribution of Molecular and Larval Morphological Characters in a Combined Phylogenetic Analysis of the Superfamily Majoidea, K. M. Hultgren, G. Guerao, F. P. L. Marques, and F. P. Palero Molecular Genetic Re-examination of Subfamilies and Polyphyly in the Family Pinnotheridae (Crustacea: Decapoda), E. Palacios-Theil, J. A. Cuesta, E. Campos, and D. L. Felder Evolutionary Origin of the Gall Crabs (Family Cryptochiridae) based on 16S rDNA Sequence Data, R. Wetzer, J. W. Martin, and S. L. Boyce Systematics, Evolution, and Biogeography of Freshwater Crabs, N. Cumberlidge and P. K. L. Ng Phylogeny and Biogeography of Asian Freshwater Crabs of the Family Gecarcinucidae (Brachyura: Potamoidea), S. Klaus, D. Brandis, P. K. L. Ng, D. C. J. Yeo, and C. D. Schubart A Proposal for a New Classification of Portunoidea and Cancroidea (Brachyura: Heterotremata) based on Two Independent Molecular Phylogenies, C. D. Schubart and S. Reuschel Molecular Phylogeny of Western Atlantic Representatives of the Genus Hexapanopeus (Decapoda: Brachyura: Panopeidae), B. P. Thoma, C. D. Schubart, and D. L. Felder Molecular Phylogeny of the Genus Cronius Stimpson, 1860, with Reassignment of C. tumidulus and Several American Species of Portunus to the Genus Achelous De Haan, 1833 (Brachyura: Portunidae), F. L. Mantelatto, R. Robles, C. D. Schubart, and D. L. Felder Index Color Insert

Application of regression techniques to studies of relative growth in crustaceans

ABSTRACT Studies of relative growth in crustaceans are often based, in whole or in part, upon the practice of log transformation of all linear morphometric data prior to the calculation of a least squares estimate linear regression for a broad size class of specimens. This and other practices may result in misinterpretation of the regression analysis. We propose that analysis of untransformed data with a Model II regression technique such as the reduced major axis is appropriate for description of relative growth in crustacean linear morphometric features, and that data for broad size-class samples should be examined as iteratively divided subsets, rather than assuming a priori that the entire sample is adequately represented by a single continuous function. A statistical test for evaluation of regression functions on the basis of randomness of residuals is provided.

Ontogeny of osmoregulation in the estuarine ghost shrimp Callianassa jamaicense var. louisianensis Schmitt (Decapoda, Thalassinidea)

During the abbreviated development of Callianassa jamaicense var. louisianensis Schmitt, both zoeal stages exhibit hyperosmotic regulation of hemolymph in media <800–900 mOsm and conform at higher salinities, a pattern similar to adults. Hyperosmotic regulatory ability is present at the time of hatching. (Na + K)-activated ATPase activity, commonly associated with salt-transporting tissues, increases from 7.8 ± 4.3 μmol Pi·h−1·g wet wt−1 (95 % CI, n = 7) at early stages of prehatch development to reach the highest levels at hatching (96.5 ± 10.6 μmol Pi·h−1·g wet wt−1, n = 21); thereafter, larval ATPase activity decreases and then stabilizes at 56.6 ± 12.4 μmol Pi·h−1·g wet wt−1 (n=21). AgNO3 stains potential sites for osmoregulation along the inside surface of the branchiostegite and adjacent body wall in the larvae by forming silver precipitates which are identified by energy dispersive X-ray analysis. TEM studies of these sites reveal a specialized epithelium with characteristics typical of salt-transporting tissue. Thus physiological, biochemical and morphological features present in these larvae reflect an early development of osmoregulatory ability.

Ontogeny of gut morphology in the white shrimp Penaeus setiferus (Decapoda, Penaeidae)

Ontogeny of the gut in Penaeus setiferus was investigated by reconstruction of serial sections examined by light microscopy. Development of the gut into the adult form is protracted over several weeks beyond metamorphosis in steps that may be directly related to the unique postlarval life history of Penaeus. The gastric mill is lacking in larval stages of P. setiferus. In protozoeal stages Z1‐Z3, the pyloric ampullae are blind sacs that do not communicate with the midgut. The gland filter first appears in mysis stage M2. The gastric mill in early postlarval (PL) stages consists of poorly chitinized lobes with flexible setae. By PL21 the ossicles of the gastric mill are rigid and setae are replaced by spine‐like denticles, but even by PL35 the gastric mill is neither as massive nor heavily chitinized as in adults. During the mysis stages and early PL stages, the hepatopancreas communicates freely with both the foregut and the midgut trunk. By PL35 the hepatopancreatic ducts are essentially isolated from the remainder of the midgut by foregut ossicles.

Genetic, ecological, and behavioural divergence between two sibling snapping shrimp species (Crustacea: Decapoda: Alpheus)

Examination of genetic and ecological relationships within sibling species complexes can provide insights into species diversity and speciation processes. Alpheus angulatus and A. armillatus, two snapping shrimp species with overlapping ranges in the north‐western Atlantic, are similar in morphology, exploit similar ecological niches and appear to represent recently diverged sibling species. We examined phylogenetic and ecological relationships between these two species with: (i) sequence data from two mitochondrial genes (16S rRNA and COI); (ii) data on potential differences in microhabitat distribution for A. armillatus and A. angulatus; and (iii) data from laboratory experiments on the level of reproductive isolation between the two species. DNA sequence data suggest A. armillatus and A. angulatus are sister species that diverged subsequent to the close of the Isthmus of Panama, and that haplotype diversity is lower in A. armillatus than in A. angulatus. Both species are distantly related to A. heterochaelis and A. estuariensis, two species with which A. angulatus shares some similarities in coloration. Ecological data on the distribution of A. angulatus and A. armillatus from two locations revealed differences in distribution of the two species between habitat patches, with each patch dominated by one or the other species. However, there was no apparent difference in distribution of the two species within habitat patches with respect to microhabitat location. Ecological data also revealed that heterospecific individuals often occur in close proximity (i.e. within metres or centimetres) where sympatric. Behavioural data indicated that these species are reproductively isolated, which is consistent with speciation in transient allopatry followed by post‐divergence secondary contact. Our data further resolve taxonomic confusion between the sibling species, A. armillatus and A. angulatus, and suggest that sympatry in areas of range overlap and exploitation of similar ecological niches by these two recently diverged species have selected for high levels of behavioural incompatibility.

A comprehensive and integrative reconstruction of evolutionary history for Anomura (Crustacea: Decapoda).

BackgroundThe infraorder Anomura has long captivated the attention of evolutionary biologists due to its impressive morphological diversity and ecological adaptations. To date, 2500 extant species have been described but phylogenetic relationships at high taxonomic levels remain unresolved. Here, we reconstruct the evolutionary history—phylogeny, divergence times, character evolution and diversification—of this speciose clade. For this purpose, we sequenced two mitochondrial (16S and 12S) and three nuclear (H3, 18S and 28S) markers for 19 of the 20 extant families, using traditional Sanger and next-generation 454 sequencing methods. Molecular data were combined with 156 morphological characters in order to estimate the largest anomuran phylogeny to date. The anomuran fossil record allowed us to incorporate 31 fossils for divergence time analyses.ResultsOur best phylogenetic hypothesis (morphological + molecular data) supports most anomuran superfamilies and families as monophyletic. However, three families and eleven genera are recovered as para- and polyphyletic. Divergence time analysis dates the origin of Anomura to the Late Permian ~259 (224–296) MYA with many of the present day families radiating during the Jurassic and Early Cretaceous. Ancestral state reconstruction suggests that carcinization occurred independently 3 times within the group. The invasion of freshwater and terrestrial environments both occurred between the Late Cretaceous and Tertiary. Diversification analyses found the speciation rate to be low across Anomura, and we identify 2 major changes in the tempo of diversification; the most significant at the base of a clade that includes the squat-lobster family Chirostylidae.ConclusionsOur findings are compared against current classifications and previous hypotheses of anomuran relationships. Many families and genera appear to be poly- or paraphyletic suggesting a need for further taxonomic revisions at these levels. A divergence time analysis provides key insights into the origins of major lineages and events and the timing of morphological (body form) and ecological (habitat) transitions. Living anomuran biodiversity is the product of 2 major changes in the tempo of diversification; our initial insights suggest that the acquisition of a crab-like form did not act as a key innovation.

Reproductive Ecology of an Intertidal Brachyuran Crab, Sesarma sp. (nr. reticulatum), from the Gulf of Mexico

The natural history and reproductive ecology of a presently undescribed marsh crab endemic to the Gulf of Mexico were studied in both the laboratory and the field. Weekly sampling of populations in coastal Louisiana allowed us to determine the periodicity of molting and ovarian development, as well as the seasonal variation in egg laying and size of individual egg masses. Timing of molt, egg laying, and egg hatching were monitored in individual females under simulated tidal cycles in laboratory mesocosms. Peak periods of reproductive activity in Louisiana coincide with favorable temperatures and elevated primary productivity in coastal waters. Size cohort and fecundity differ between these periods. Egg-laying, larval release, and molting observed in individual females in the laboratory and extrapolated dates of egg-laying and larval release for those in field samples exhibit a semilunar influence throughout the season. Female receptivity to mating is tied to egg-laying. Rate of embryonic development was associated with decreases and increases in egg size. Behavior related to larval release is described. Adaptive significance in relation to the intertidal marsh habitat is discussed.

ONTOGENY OF KINEMATICS IN THE GUT OF THE WHITE SHRIMP PENAEUS SETIFERUS (DECAPODA: PENAEIDAE)

Motility of the gut in developmental stages of Penaeus setiferus (Linnaeus) was monitored in vivo with video microscopy. Oral drinking, anal drinking, and propagation of contractile waves in the midgut trunk (MGT) were observed in larval and postlarval stages. A gastric mill and functional gland filter were absent in larvae. In early postlarval stages, the gastric mill did not function in trituration. The gland filter appeared to function in emulsification rather than in exclusion of large-sized particles from the hepatopancreas. Chyme from within the peritrophic membrane, as far posteriad as abdominal segment 2, was moved at times anteriad into the hepatopancreas. Both antiperistaltic and peristaltic waves mixed and transported chyme within the midgut. Substantial ontogenetic change in function of the foregut and midgut occurred (1) at metamorphosis, (2) at onset of motility in the median tooth, and (3) with differentiation of hepatopancreatic tubules. We propose that antiperistalsis along the MGT, anal drinking, oral drinking, and contractions of the foregut maintain positive hydraulic pressure within the midgut. This pressure expands regions of the midgut following contractions of intrinsic muscles. Hydraulic pressure, particularly that propagated by antiperistalsis of the MGT, is responsible for expansion of contracted hepatopancreatic tubules. We further propose that the peritrophic membrane separates stored chyme and rejected fecal matter from water taken up by anal drinking and pumped anteriad by antiperistaltic waves. In P. setiferus hydraulic pressure in the extraperitrophic space of the midgut lumen, together with pressure exerted by constriction of the MGT in abdominal segments 3 and 4, compresses the peritrophic membrane around its contents. This compression expels fluids anteriad and compacts feces before the fecal strand reaches the hindgut.