Frank D. Ferrari

Interpreting segment homologies of the maxilliped of cyclopoid copepods by comparing stage-specific changes during development

Abstract Development of the maxilliped of 14 species of cyclopoid copepods from 14 genera in the families Cyclopinidae, Oithonidae and Cyclopidae is described. Segment homologies are inferred from the assumption that homologous setae and arthrodial membranes are added during the same copepodid stage, and from a model of development that patterns the endopod proximally from the proximal of two endopodal segments present at the first copepodid stage. An arthrodial membrane separates the praecoxa and coxa of two Cyclopinidae and two of three Oithonidae. The praecoxa of the Cyclopinidae and the Oithonidae has two groups of setae; the praecoxa of Cyclopidae has no more than one group. The coxa of these copepods has only one group of setae; all Cyclopidae share a coxal lobe with a single seta. The endopod of these three families may include as many as five segments. In general, the distal arthrodial membrane of a segment appears to have been more labile during evolutionary history of the maxilliped than has the ventral seta which inserts on that segment. For purposes of phylogenetic analyses, uncoupling the presence of the distal arthrodial membrane of a segment from the presence of its ventral seta and analyzing each separately may provide a better way of understanding evolutionary transformations of the limb than considering the segment as the basic structural unit of the limb.

Very Bright Green Fluorescent Proteins from the Pontellid Copepod Pontella mimocerami

Background Fluorescent proteins (FP) homologous to the green fluorescent protein (GFP) from the jellyfish Aequorea victoria have revolutionized biomedical research due to their usefulness as genetically encoded fluorescent labels. Fluorescent proteins from copepods are particularly promising due to their high brightness and rapid fluorescence development. Results Here we report two novel FPs from Pontella mimocerami (Copepoda, Calanoida, Pontellidae), which were identified via fluorescence screening of a bacterial cDNA expression library prepared from the whole-body total RNA of the animal. The proteins are very similar in sequence and spectroscopic properties. They possess high molar extinction coefficients (79,000 M−1 cm−) and quantum yields (0.92), which make them more than two-fold brighter than the most common FP marker, EGFP. Both proteins form oligomers, which we were able to counteract to some extent by mutagenesis of the N-terminal region; however, this particular modification resulted in substantial drop in brightness. Conclusions The spectroscopic characteristics of the two P. mimocerami proteins place them among the brightest green FPs ever described. These proteins may therefore become valuable additions to the in vivo imaging toolkit.

Setal developmental patterns of thoracopods of the Cyclopidae (Copepoda : Cyclopoida) and their use in phylogenetic inference

ABSTRACT Thoracopod development was analyzed for 25 species from 18 genera among the Cyclopidae. One species from each of 7 genera of presumed older cyclopoids, 5 poecilostomatoid genera, 3 harpacticoid genera, 5 calanoid genera, and a siphonostomatoid were studied to help establish ancestral patterns of thoracopod development. Ancestral character states were inferred from the presence of identical states in species from presumed older families, from the presence of states which show diverse and frequent occurrence among the Copepoda, or from the presence of states shared by serially homologous structures presumed to be determined by the same pleiotropic regulatory process. Developmental patterns of the 4 swimming legs were assumed to result from the action of 2 different regulatory processes. A pleiotropic process acting early in development determines the morphology of all 8 rami together and results in 3 states among cyclopids, ancestral, and the independently derived delayed and truncated patterns. A second set of up to 8 regulatory processes acts later and one of the 8 determines the morphology of each individual ramus. The ancestral states of the resulting individual rami are, by default, the morphology that results from the pleiotropic regulatory process. Variations in developmental patterns were used to generate a phylogenetic hypothesis. Cyclopids have separated into a lineage of 10 species which has delayed the development of the swimming legs or has modified some individual rami from the delayed condition, and a lineage of 8 species which has truncated the development of the swimming legs or has modified some individual rami from that truncated condition. Four species have retained the ancestral process regulating swimming-leg development and 3 species have modified development of some individual rami from the ancestral condition.

Body Architecture and Relationships Among Basal Copepods

Abstract Most copepods exhibit one of three kinds of body architecture: 1) six broad anterior trunk somites and five narrow posterior trunk somites of gymnopleans; 2) five broad anterior trunk somites and six narrow posterior trunk somites of many podopleans; or 3) four broad anterior trunk somites and seven narrow posterior trunk somites of thaumatopsylloids. A phylogenetic analysis using naupliar and post-naupliar characters, with Mystacocarida as the sister taxon of Copepoda, supports the hypothesis that the thaumatopsylloid architecture is the oldest. No narrow somite is transformed into a broad somite during post-naupliar development of thaumatopsylloids. Podopleans and gymnopleans begin their post-naupliar development with one trunk somite fewer than thaumatopsylloids. Podoplean architecture results when the anterior narrow somite of thaumatopsylloids is transformed to the posterior broad somite of podopleans during the first post-naupliar molt. Gymnoplean architecture, the youngest, results when the anterior narrow somite found on podopleans is transformed to the posterior broad somite during the second post-naupliar molt. These developmental transformations of body somites are assumed to explain the evolutionary origins of podoplean and gymnoplean body architectures.

Early Post-Embryonic Development of Marine Chelicerates and Crustaceans with a Nauplius

Crustaceans that hatch as a nauplius-like larva, as well as xiphosuran and pantopodan chelicerates, are surveyed for five characters: presence or absence of arthrodial membranes separating somites; ventral configuration of the protopod of the second limb; number of transformed (segmented) limbs and limb buds; addition of segments to transformed limbs; fate of limb buds. An arthrodial membrane separates somites 7 and 8 of xiphosurans, a small knob articulates on the protopod of the second limb, and there are nine pairs of limbs but no limb buds. During early development, no arthrodial membranes are added, nor are segments added to limbs 1-9; limbs 10-14 are added as transformed limbs, not as limb buds, after several molts. On the post-embryonic larva of the presumed ancestral pantopodan, arthrodial membranes did not separate adjacent somites, the proximal segment of limb 2 was simple, there were three transformed limbs and no limbs buds. During subsequent molts, arthrodial membranes separated somites 4-7, buds of limbs 4-7 were added in register with each molt, limb buds were reorganized in register into transformed limbs during the following molt, and two segments were added to each transformed limb in register during the next molt. Somites of most crustacean taxa that hatch as a nauplius-like larva are not separated by arthrodial membranes on early post-embryonic stages; exceptions are posterior somites of branchiurans, mystacocaridans and cephalocaridans. Limb 2 (antenna 2) of branchiopods, copepods, thecostracans, mystacocaridans and cephalocaridans bears a naupliar arthrite on the ventral face of the coxa, on branchiurans there is an attenuation, or spine-like outgrowth, on the ventral face, and on 5) Corresponding author; e-mail: ferrarif@si.edu 6) e-mail: johnfornshell@hotmail.com 7) e-mail: avagelli@njaas.org 8) e-mail: ivanenko@mail.bio.msu.ru 9) Co-corresponding author; e-mail: hansdahms@smu.ac.kr

Nauplii of Tegastes falcatus (Norman, 1869) (Harpacticoida, Tegastidae), a Copepod with an Unusual Naupliar Mouth and Mandible

There are six stages in the naupliar phase of development of Tegastes falcatus (Norman, 1869). The labrum is expressed as a simple fold which does not cover the mouth. A poorly-sclerotized mouth tube was observed on some specimens of all stages except NI (= naupliar stage 1); NI and Nil are the only stages without an anus and presumably do not feed. The antennal endopod is a subchela against itself at Nil; its distal endopodal segment becomes bifurcate at NIII. A chela on the naupliar mandible consists of the endopod opposite a distoventral attenuation of the basis on NII-NVI. The segmental elements of a chela are present at NI, although the endopod does not oppose the basis at this stage. The maxillule is a unilobe bud with one seta at NIII that gains a second seta at NV and is transformed into a simple bilobe bud with three setae at NVI. The maxilla and maxilliped are each an asetose, ventral attenuation at NVI. Naupliar stages, found in large numbers along with all six copepodid stages of T. falcatus, apparently feed on suctorian ciliates growing on colonies of the bryozoan Flustra foUacea (Linnaeus, 1758). This is the first description of six naupliar stages for a species of Tegastidae Sars, 1904.

Patterns of Setal Numbers Conserved during Early Development of Swimming Legs of Copepoda (Crustacea)

During swimming leg development, the number of setae present on the exopod and endopod of the bilobed bud, the transformed swimming leg with 1-segmented rami and the swimming leg with 2-segmented rami of copepods is analysed. For swimming leg 1, the most frequent number of setae on the presumptive rami of the bilobed bud is found at a higher percentage among copepod species than the most frequent number of setae for either the transformed swimming leg with 1-segmented rami or the swimming leg with 2-segmented rami. However, for swimming legs 2–4 the most frequent number of setae for the the transformed swimming leg with 1-segmented rami is found at a higher percentage of species than that on either the bilobed bud or the swimming leg with 2-segmented rami. Thus, in the cases of swimming legs 2–4, species with different numbers of setae on the presumptive exopod and endopod of the bud bilobed bud develop the same number of setae on the rami of the transformed swimming leg with 1-segmented rami. Increasing the number of species analysed is expected to make more robust the hypothesis that the number of setae on the transformed swimming leg with 1-segmented rami is conserved relative to the number of setae on the bilobed bud.

Segmental homologies of the maxilliped of some copepods as inferred by comparing setal numbers during copepodid development

Segmental homologies of the maxillipeds of Longipedia americana, Coullana canadensis, Macrosetella gracilis, Hemicyclops adherens, and Troglocyclops janstocki are inferred by comparing segmental and setal numbers at CI, and changes in setal numbers during the copepodid phase of development, with published accounts of the calanoids Ridgewayia klausruetzleri and Pleuromamma xiphias. The unsegmented endopod of L. americana is a complex of 4 presumptive segments and the unsegmented endopod of C. canadensis is a complex of 3 presumptive segments. The endopod of T. janstocki appears to be 3-segmented, but the middle segment is a complex of 3 presumptive segments. Macrosetella gracilis has an unsegmented endopod of 2 presumptive segments; the distal segment is attenuate, forming a clawlike structure. Hemicyclops adherens has a 2-segmented endopod; the prominent, clawlike terminal structure on the maxilliped of the adult male is an attenuation of the distal endopodal segment. A homologous but more complex attenuation of that segment is present on the maxilliped of all of its copepodid stages including the adult female. Copepods exhibit a significant diversity in the morphology of their maxilliped, particularly in the number of segments and segmental armature of the endopod. We examine the

A new epacteriscid copepod (Calanoida: Epacteriscidae) from the Yucatan Peninsula, Mexico, with comments on the biogeography of the family

ABSTRACT The calanoid copepod family Epacteriscidae is represented by species from tropical marine and anchialine environments. Surveys of the anchialine invertebrate fauna of the Yucatan Peninsula, Mexico, have resulted in a number of interesting records of crustaceans during the last decade, but no records of Epacteriscidae. However, recent collections from hypogean environments of the Yucatan have yielded specimens of a new species of the previously monotypic genus Balinella. The specimens were included in this genus by having three outer spines on the third exopodal segment of legs 3 and 4, a biramous mandibular palp, and an antennal endopod longer than the exopod, among other characters. The new species, B. yucatanensis, is described on the basis of male and female specimens collected in caves associated with three different karstic sinkholes. The new species is distinguished from its only known congener, B. ornata Fosshagen, Boxshall and Iliffe, 2001, by the strong asymmetry of the caudal rami in females, a modified left fifth leg of the male in which the proximal and middle exopodal segments are attenuate at the point of origination of the outer spine, and by differences of the armature of mouthparts (mandibular palp, maxilla, maxilliped). This report extends the range of Balinella from anchialine caves of the Bahamas to hypogean waters of the Yucatan Peninsula. The introduction of epacteriscid copepods onto the Yucatan Peninsula may be an old event; diversification by genera into non-cave habitats appears to be secondary.

RELATIONSHIPS BETWEEN ARTHRODIAL MEMBRANE FORMATION AND ADDITION OF SETAE TO SWIMMING LEGS 1-4 DURING DEVELOPMENT OF DIOITHONA OCULATA, RIDGEWAYIA KLAUSRUETZLERI, PLEUROMAMMA XIPHIAS, AND TEMORA LONGICORNIS (COPEPODA)

Relationships between arthrodial membrane formation and the addition of setae to the exopod and endopod of swimming leg 3 of the cyclopoid copepod Dioithona oculata are derived from formation homologies during development. Based on this information, these relationships are inferred for the remaining swimming legs of the cyclopoid and the swimming legs of three calanoids, Ridgewayia klausruetzleri, Pleuromamma xiphias, and Temora longicornis. Most of the variation in setal numbers for a leg among the four copepods is expressed in the distal segment of each ramus. The most striking differences in architecture result from a delay or failure in expression of the arthrodial membranes which separate the proximal segment or the middle segment of the ramus from the distal segment. Inferring a composite model for relationships between arthrodial membrane formation and addition of setae to the exopod and endopod of a swimming leg is complicated by differences in swimming leg 1 and the remaining swimming legs which includes an earlier allocation of the proximal seta of the middle (third) segment to both rami of swimming leg 1. These developmental patterns are presumed to be derived, and the endopod of all thoracopods of the ancestral copepod immediately after the transformation of the leg bud is presumed to have been 2-segmented with one medial seta on the proximal segment.