William A. Newman

Juvenile Hormone Mimics: Effect on Cirriped Crustacean Metamorphosis

A synthetic juvenile hormone mimic has been shown to cause premature metamorphosis of the cyprid larva of an acorn barnacle in concentrations as low as 10 parts per billion in filtered seawater. The effect of a juvenile hormone mimic on a crustacean has not previously been demonstrated.

A pilot study of heavy metal accumulations in a barnacle from the Salton Sea, Southern California☆

Accumulations of Fe, Cu, Zn, Cd, Sn, Hg and Pb in body tissues and egg masses of Balanus amphitrite were measured with an inductively coupled plasma source mass spectrometer (ICP-MS). Barnacles proved to be a good choice as a sentinel species for monitoring of heavy metals. A comparison of their levels in the animals inhabiting the Salton Sea with those from coastal waters of the Pacific Ocean showed that the sea, contrary to expectations, has not been severely contaminated by heavy metals. The accumulations of the metals in barnacle bodies and eggs varied markedly between the stations but appeared least where organic pollution was highest.

Holocene Changes in Sea Level: Evidence in Micronesia

Investigation of 33 islands, scattered widely across the Caroline and Marshall Island groups in the Central Pacific revealed no emerged reefs in which corals had unquestionably formed in situ, or other direct evidence of postglacial high stands of sea level. Low unconsolidated rock terraces and ridges of reefflat islands, mostly lying between tide levels, were composed of rubble conglomerates; carbon-14 dating of 11 samples from the conglomerates so far may suggest a former slightly higher sea level (nine samples range between 1890 and 3450 and one approaches 4500 years ago). However, recent hurricanes have produced ridges of comparable height and material, and in the same areas relics from World War II have been found cemented in place. Thus these datings do not in themselves necessarily indicate formerly higher sea levels. Rubble tracts are produced by storms under present conditions without any change in datum, and there seems to be no compelling evidence that they were not so developed during various periods in the past.

Molecular investigations of the stalked barnacle Vulcanolepas osheai and the epibiotic bacteria from the Brothers Caldera, Kermadec Arc, New Zealand

The hydrothermal-vent barnacle Vulcanolepas osheai of the subfamily Neolepadinae is one of the most conspicuous organisms at the Brothers Caldera, south Kermadec Arc, New Zealand. Like a neolepad species found in the Lau Basin, V. osheai harbours filamentous bacteria on its elongated cirral setae. To define the phylogenetic affiliation of the epibiotic bacteria and the nutrition of the barnacle host, we conducted molecular phylogenetic and isotopic analyses. Analysis of 16S rRNA gene sequences of microbial communities on the cirral setae showed that among 91 bacterial sequences investigated, 2 8 sequences were related to the s-proteobacterial endosymbiont of Alviniconcha aff. hessleri; 11 sequences were related to the epibiont of the bresiliid shrimp Rimicaris exoculata. Fluorescence in situ hybridization showed that in contrary to results from the 16S rRNA gene-sequence library, approximately 80% of the filamentous bacteria hybridized with a probe targeting the sequences related to the epibiont of the bresiliid shrimp R. exoculata. The fatty-acid profiles of the filamentous bacteria and the host barnacle both contained high levels of monounsaturated C 16 and C 18 fatty acids, and the carbon isotopic compositions of the biomass and monounsaturated C 16 and C 18 fatty acids of both the bacteria and barnacle were nearly identical. This would suggest that the nutrition of the barnacle is highly dependent on bacteria thriving around the barnacle, including the epibiotic bacteria.

Origin of the Ostracoda and their maxillopodan and hexapodan affinities

There are Cambrian fossils attributed to the Ostracoda but the extant subclasses Podocopa and Myodocopa do not appear until the Ordovician. At this time the morphologically similar, free-living ancestors of the now sedentary Thecostraca (Ascothoracida, Acrothoracica and Cirripedia) may have still been extant, and from an ecological point of view it seems likely that, by and large, ostracods replaced them. However, living ostracods have an abbreviated, direct development, and some key aspects of their morphology, such as the nature of the maxillary segment and abdomen, are conjectural. Thus the affinities between these and related taxa remain uncertain; e.g., while some contemporary carcinologists place Ostracoda as a taxon coordinate with the Branchiopoda, Remipedia, Cephalocarida, Maxillopoda, Malacostraca, others tentatively or unequivocally ally them with the Maxillopoda (generally Mystacocarida, Copepoda, Tantulocarida and Thecostraca, and sometimes Branchiura and Pentastomida). Others, largely involved with fossils, have stretched the definition of the Maxillopoda even further, to the point where it seems even less likely a monophyletic taxon. Until recently cladistic analyses utilizing genetic (largely 18S rDNA) as well traditional morphological characteristics have given confusing results regarding the affinities between these taxa, and an important one suggested the Ostracoda might even be diphyletic. Furthermore, a very recent genetic study utilizing protein encoding genes places a podocopine ostracod among the most primitive of the extant crustaceans (Branchiopoda, Cephalocarida Remipedia and Mystacocarida), and then generally at the base of a lineage leading to the Malacostraca, a lineage giving rise to copepods and cirripeds along the way. This indicates these so-called maxillopodan taxa evolved independently from a malacostracan-like ancestor, and if so they are convergent. And finally, from genetic studies it is not only becoming well documented the Crustacea rather than Myriapoda gave rise to the Hexapoda, but it appears the Hexapoda stem from among the lower rather than the higher crustaceans, possibly even from the Ostracoda. Whether there were terrestrial ostracods at the time hexapods appeared in the Lower Ordovician is unknown, but the modest diversity of terrestrial ostracods today are podocopines which also first appeared in the Lower Ordovician. Thus, if current interpretations of living ostracodan and fossil hexapodan body plans are largely correct, it can be hypothesized the Ostracoda are close to the ancestor of the Hexapoda.

Acrothoracica, Burrowing Crustaceans

This monograph is the first major overview of the order Acrothoracica since Tomlinson (1969). This is an exclusively marine group of gonochoristic (dioecious) barnacles. Females, generally accompanied by one or more dwarf males, excavate burrows largely in carbonate substrates and are therefore referred to as the burrowing barnacles. While their greatest diversity is found in shallow tropical seas, the most generalized or primitive members are found for the most part in deep water (between 1000 and 3000 m). Trace fossils, ranging back to the Devonian if not the Ordovician (Taylor and Wilson, 2003), reveal that species once occupied relatively high latitudes in Northern Europe and Gondwanaland, and at least one extant species is known from Antarctic waters today. The author, Gregory Kolbasov, dedicates this work to his late professor, Galena Zevina, whose premature death in 2002 constituted a major setback for cirripedology in general (Kolbasov et al., 2005). The dedication and the bulk of the following text are in Russian, but a 25-page summary and some two-thirds of the references are in English. Furthermore, the ordinal, familial, and generic diagnoses, and the characters used in the cladistic analysis, are also in English. Regrettably, for the English-speaking reader the key to the genera and species is in Russian, but this is in good part compensated for by 153 well-executed line drawings, SEMs, and charts, all of which have captions in English as well as Russian. All in all, this is a volume most any serious worker on crustaceans as well as cirripedes would want close at hand, at least until a promised multi-authored English version becomes available. The work lacks a general subject index, but there is a computer-generated one for hosts as well as the acrothoracican taxa, and the pages where definitions are to found in boldface. Even so, not to be able to easily find a species in the index by its trivial name alone can be inconvenient, especially if it is one of the 10 or so whose generic name has recently changed. The revisionary aspects of this monograph include a taxonomic reorganization whereby the families Lithoglyptidae Aurivillius, 1892 and Cryptophialidae Gerstaecker 1866 (heretofore included in the suborder Pygophora Berndt, 1907) are split between two new orders, Lithoglyptida nov. and Cryptophialida nov., whereas Trypetesidae Stebbing, 1910 (heretofore the sole family of Apygophora Berndt, 1907) is now placed in Lithoglyptida along with Lithoglyptidae (Table 1). As can be seen in the table, Tomlinson’s monograph included two orders, three families, nine genera, and a modest diversity of 37 species. Since Tomlinson, while the number of genera has increased from but 10 to 11 [including Balanodytes taiwanensis (Utinomi, 1950) which, while cross-referenced, was inadvertently left out of the text (cf. Kolbasov and Newman, 2005, present status), the number of species has risen to approximately 63, i.e., almost double. However, not only has it turned out that an inference of Kolbasov’s that Balanodytes Utinomi, 1950 was a junior synonym of Armatoglyptes (Kolbosov and Newman, 2005) was correct, but also it has been determined that Balanodytes taiwanensis Utinomi, 1950, Lithoglyptes habei Tomlinson, 1963, and Lithoglyptes balanotytes Kolbasov, 2000 are synonymous of Armatoglyptes taiwanensis (Utinomi, 1950) [BKK Chan, personal communication]. The portion of the monograph in Russian is divided between 6 chapters; 1) Historical background, 2) Morphology of females and dwarf males, 3) Embryology and larval (naupliar and cyprid) development, 4) Phylogeny and classification, 5) Geographical distribution, and 6) Female-host interactions. This is followed by a summary in English that, while sidestepping the historical introduction, subdivides the remaining material between 8 rather than 6 chapters or sections. The first of the 8 sections is on external functional morphology and the polarity of evolution in females, males being taken up in section 3. Here the evolution of various parts is discussed, and interesting trends are noted, such as a correlation between reduction in the size of the aperture and the number of cirri. The second section concerns the presence of a calcareous plate in acrothoracicans, first reported upon in the deep-sea species, Weltneria hessleri and W. exargilla (cf. Newman, 1974). It was believed at that time the acrothoracicans had a pedunculate ancestry, a notion stemming from Darwin and promulgated by Tomlinson (1969). It followed that the calcareous plate was potentially homologous with the rostral plate of scalpellomorphs, a misconception rectified by Grygier and Newman (1985). Kolbasov now suggests the plate is basal rather than rostral in position, and is ‘‘... homologous to the calcareous base of some thoracicans.’’ However, not only has molecular genetics (Pérez-Losada et al., 2008) shown the acrothoracicans are separated from the thoracicans by the plate-less Rhizocephala, a calcareous basis is largely confined to the higher balanomorphs. Thus, it would appear the calcareous plate of some acrothoracicans is convergent with those in thoracicans. Yet, it tends to occur in the primitive members (Grygier and Newman, 1984). JOURNAL OF CRUSTACEAN BIOLOGY, 31(1): 209–211, 2011