Les articles ainsi que les nouveautés nomenclaturales publiés dans Zoosystema sont référencés par / Articles and nomenclatural novelties published in Zoosystema are referenced by:-ZooBank ® (http://zoobank.org)
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The Engraulis ringens distribution (4 to 42°S) covers a wide variety of environmental conditions. We assessed the coping mechanisms used by this anchoveta in different spawning habitats, reporting differences in egg traits between populations off northern (Iquique, 20°S) and southern Chile (Talcahuano, 36°S) and throughout the spawning season. Eggs were smaller off Iquique, declined in size during the reproductive season (both populations), and inter-population differences persisted throughout the spawning season. Batch fecundity (eggs per batch per female) and relative fecundity (eggs per female weight) were lower off Talcahuano during the peak spawning months. Thus, larger eggs spawned in the southern population seem to be produced at the cost of a reduction in fecundity. The eggs also differed biochemically between the 2 populations; total lipids and triacylglycerides were much higher off Talcahuano. The biochemical composition (both populations) also changed throughout the spawning season, with higher lipids early in the spawning season (July to August) off Talcahuano. Hatching success decreased during the spawning season, and correlated positively with egg size and lipid contents. Environmental conditions differed markedly between spawning areas and from mid-winter to late spring. Off Talcahuano, the temperature and winter-time water column productivity are lower and turbulence is higher, while eggs are larger, lipid contents higher, and batch fecundity lower. This mechanism seems to facilitate survival of young offspring in the more adverse winter conditions off Talcahuano. These egg characteristics are determined by the adult female reproductive system, representing a maternal influence on the early life-history traits of anchoveta that might enable rapid changes in population densities in some years of improved habitat conditions. KEY WORDS: Anchoveta · Engraulis ringens · Upwelling · Reproductive strategy · Egg quality · Lipids · Humboldt Current · Small pelagic fishes
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Glypheids first appeared in the Lower Triassic period and were believed to be extinct until specimens of Neoglyphea inopinata Forest & Saint Laurent and Laurentaeglyphea neocaledonica Richer de Forges were described in 1975 and 2006, respectively. The finding of extant species has meant that molecular data can now be used to complement morphological and fossil-based studies to investigate the relationships of Glypheidea within the Decapoda. However, despite several molecular studies, the placement of this infraorder within the decapod phylogenetic tree is not resolved. One limitation is that molecular resources available for glypheids have been limited to a few nuclear and mitochondrial gene fragments. Many of the more recent large-scale studies of decapod phylogeny have used information from complete mitogenomes, but have excluded the infraorder Glypheidea due to the unavailability of complete mitogenome sequences. Using next-generation sequencing, we successfully sequenced and assembled complete mitogenome sequences from museum specimens of N. inopinata and L. neocaledonica, the only two extant species of glypheids. With these sequences, we constructed the first decapod phylogenetic tree based on whole mitogenome sequences that includes Glypheidea as one of 10 decapod infraorders positioned within the suborder Pleocyemata. From this, the Glypheidea appears to be a relatively derived lineage related to the Polychelida and Astacidea. Also in our study, we conducted a survey on currently available decapod mitogenome resources available on National Center for Biotechnology Information (NCBI) and identified infraorders that would benefit from more strategic and expanded taxonomic sampling.
Whole body oxygen consumption and some hemolymph parameters such as pH, partial pressure of gases, level of ions and lactate were measured in the estuarine crab Chasmagnathus granulata after both acute (96 h) and chronic (2 weeks) exposure to cadmium at concentrations ranging from 0.4 to 6.3 mg/l. In all instances, the crabs developed hemolymph acidosis, but no respiratory (increased P CO 2 ) or lactate increases were evident. Hemolymph levels of sodium and calcium were always increased by cadmium exposure. The chronic toxicity of cadmium was enhanced at 12 salinity, even causing a significantly higher mortality in comparison with the higher salinity (30) used. A general metabolic arrest took place at 12 salinity in the crabs chronically exposed to cadmium, as indicated by decreases of oxygen consumption and P CO 2 , an increase of P O 2 , along with no changes in lactate levels. These imbalances were associated with severe necrosis and telangiectasia in the respiratory gills, probably leading to respiratory impairment and finally histotoxic hypoxia and death of the animals.
Correspondence
To determine the beginning and end of the transition period from larvae to juveniles in anchoveta Engraulis ringens, seven morphometric measurements were carried out in 333 laboratory-reared and 324 field-caught larvae. Measurements of body morphometrics were employed to calculate the six body ratios selected to show transition changes described in this study. The analysis was carried out with 'dummy variables' (variables that take only one of two possible values: 0 or 1) because a single model was used to indicate the point at which the slope changes in piecewise linear regressions. The regression coefficients of the relationship between ratios of morphometric measurements and body length were not significant in any case (P > 0·05) and, accordingly, a discrete length at which the slope changes could not be estimated. The ratio of the measurements according to the age showed two inflections, corresponding to the beginning and end of the transition period. The first inflection occurred between 32 and 64 days (average 46 days); the second inflection occurred between 81 and 149 days (average 107 days). Therefore, the transition period lasted c. 61 days, starting with a high growth rate, continuing with a slower growth phase, and ending with the onset of a new high growth rate period that corresponded to the start of typical juvenile growth. On the basis of these results, it is hypothesized that the transition from larvae to juveniles in E. ringens is determined more by age than body size.
The present study describes a new species of Arcoscalpellum Hoek, 1907, and a new species of Gymnoscalpellum Newman & Ross, 1971, collected by deep-sea expeditions led by the Muséum national d'Histoire naturelle (Paris) in the Coral Sea off New Caledonia, Papua New Guinea (PNG), the Solomon Islands and Vanuatu. Arcoscalpellum epeeum sp. nov. differs from all described species of Arcoscalpellum by the presence of a long, sharp, sword-shaped carina, which extends beyond the apices of the terga by 1/3 to 1/4 of their length. The species is dioecious, with large females and dwarf males that are sac-like, lack shell plates and are housed in paired receptacles at the inner edges of the scutal plates. Arcoscalpellum epeeum sp. nov. was collected in the waters of New Caledonia and Vanuatu. Gymnoscalpellum indopacificum sp. nov. differs from the six currently described species of Gymnoscalpellum by having a very small inframedian latus and a branched upper latus. The species is dioecious, with large females and dwarf males, the latter composed of 4 shell plates and housed in paired receptacles at the inner edges of the scutal plates. The penis of the dwarf males of G. indopacificum sp. nov. is about 0.8 of the total length of the male and has five side branches extending out along its length. Gymnoscalpellum indopacificum sp. nov. is distributed in the waters of Papua New Guinea, the Solomon Islands and Vanuatu, and represents the first record of this genus in the Indo-Pacific region.
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