2nd Segment Research Articles

Zur wirklichen Verbreitung von Orthetrum coerulescens (Fabricius) und O. ramburi (Selys) = O. anceps (Schneider) in Europa und die Konsequenzen für deren taxonomischen Rang (Odonata, Libellulidae) ‘Actual distribution and taxonomic rank of Orthetrum coeru

Orthetrum coerulescens (Fabricius) and O. anceps (Schneider) are very closely related forms, the first of which is distributed in Europe farther northwest than the latter. For the distinction of these two forms, only one reliable character (structure of lamina anterior of the 2nd abdominal segment in males) can be utilized. A review of the localities of museum specimens revealed that the two taxa are allopatric with a belt of secondary intergradation along the line of contact. Hybrid populations exist in Sicily as well as in Hungary and former Yugoslavia. Whereas the influence of Orthetrum coerulescens on the phenotypes decreases gradually from west to east on the Balkan peninsula (but is still recognizable even on Crete), the parental forms persist, isolated by the “Strait of Bonifacio”, on Sardinia and Corsica, respectively. Single hybrids have been found, however, far outside the zone of secondary intergradation. It is obvious, hence, that Orthetrum coerulescens and O. anceps are not full species but either members of a superspecies or even subspecies which would have to be united under the older name Orthetrum coerulescens (Fabricius).

Sampling effort and fish species richness in small terra firme forest streams of central Amazonia, Brazil

Small streams are important components of the landscape in terra firme forests in central Amazonia and harbor a large number of fish species. Nevertheless, the lack of a common sampling protocol in studies of this ichthyofauna hinders comparisons among available results. This study evaluates how the length of stream reach sampled affects estimates of local fish species density in 1st, 2nd, and 3rd order streams, and proposes a mean minimum sampling length that best approximates the absolute number of species in a given stream segment. We sampled three streams in the Biological Dynamics of Forest Fragments Project's study sites, between May and August 2004. At each stream, one 1st order, one 2nd order, and one 3rd order segment was sampled. We sampled five 20-m reaches in each stream segment. Three to four people collected along each reach for 45 to 60 minutes. We used Jaccard's coefficient to estimate the similarity of species composition among stream reaches and segments. Estimates of species richness were obtained with Jackknife 1 and Bootstrap algorithms and species accumulation curves. We used simple linear regressions to look for relationships between species density and fish abundance and between species density and the volume of 100-m stream segments. Species density in 1st order stream reaches was slightly higher than in 2nd and 3rd order stream reaches, whereas fish abundance was apparently higher in 3rd order reaches. Similarity in fish species composition between 20-m reaches was low for all studied streams. Species density values in pooled 100-m stream segments represented 71.4% to 94.1% of the estimated values for these streams. Species density showed a direct relationship both with volume of the sampled stream segment and fish abundance. It seems plausible that larger streams contain a higher number of microhabitat types, which allow for the presence of more fish species per stream length. Based on the values of asymptotes and equations for species accumulation curves, the mean minimum sampling length that best estimates the absolute number of species in a stream segment is 180 m ± 20 sd for 1st order segments; 213 m ± 23 sd for 2nd order segments, and 253 m ± 30 sd for 3rd order stream segments.

Sexual maturation in captive spiny lobsters, Jasus edwardsii, and the relationship of fecundity and larval quality with maternal size

Summary Reproductive and somatic parameters of southern rock lobsters, Jasus edwardsii, held captive since puerulus and wild-caught adults were examined in terms of size at onset of maturity (SOM) and fecundity, culminating in an examination of how adult size may relate to larval competency. The SOM was much smaller in captive animals (62.5 mm carapace length, CL) compared to historical fishery data and indicated that precocious maturation may be induced in captivity. During this study, the fecundity was assessed as the number of viable phyllosoma at hatch, which was ~45% of egg estimates from the historical fishery data, suggesting either declining egg numbers in wild stocks over time or that major egg loss occurs during embryonic development. The association between SOM and sexual dimorphism was examined for several morphometric parameters. In females, the SOM was concomitant with increases to the width of the 1st and 2nd abdominal segments above 62.5 mm CL, while 2nd and 3rd leg length increased disproportionately in males compared to females above 77.5 mm CL. There were significant correlations between viable fecundity and female size (r = 0.92), phyllosoma size (r = 0.74) and larval viability as quantified by stress indices (r = −0.56) and LD-50 (r = 0.56), indicating that larger females produce larger, more viable larvae. These physiological traits in larval, juvenile and adult animals may have an impact on fishery and aquaculture production.

Analysis of the Heart Rate and Oxygen Uptake Time Responses During Maximal Exercise

Early studies postulated that oxygen uptake (VO2) and heart rate (HR) keep linearity during progressive exercise. Nevertheless, other works showed a breakpoint on the HR temporal response, associated probably, to the anaerobic threshold (AT). PURPOSE: to analyze the relationship between the HR and VO2 time responses during progressive and maximal exercise. METHODS: Twenty-four healthy male soccer players (22±5yr, 74±7kg, 177±7cm) performed a progressive and maximal running test. Pulmonary gas exchange was analyzed breath-by-breath, and the HR was recorded each R-R period. Blood lactate concentration (BLC) was analyzed on the end of each stage. The AT was expressed by the gas exchange (ventilatory threshold - VT and respiratory compensation - RC) and the BLC (lactate threshold - LT). The values of VO2, HR and BLC, after cubic interpolation for phase alignment, were filtered (zero crossing moving average). Sequentially, HR was fitted for all possible divisions into 3 contiguous lines, and the array yielding the least-pooled residual sum of squares was chosen as representing the best fit, and further two breakpoints (HR1 and HR2) were obtained. The coefficients for each HR segment were compared to that of VO2 using t-paired Student' test (?=0.05), and the relation between breakpoints and the AT was expressed by Pearson coefficient RESULTS: Maximal VO2 (VO2max), HR and BLC averaged 62.9±6.1 ml.kg-1.min−1, 189±8bpm and 16.8±3.5mM respectively. The HR breakpoints averaged 43.9±5.9 and 89.7±7.5% of the VO2max, which resulted, on average, in weak correlation with VT (r=0.23; ns), RC (r=0.42;p<0.05) and LT (r=0.77; p<0.05). The HR and VO2 were strongly correlated (r=0.99; p<0.01) until HR1, decaying to 0.85 (p<0.05) until HR2. On the other hand, at intensities higher than that point, HR increase rate presented a drop, resulting in 57% of the explained variance of VO2 (r=0.75; p<0.05). Furthermore, calculating the difference between the expected (extrapolation of the 2nd segment) and measured HR values for the 3rd segment, we found a chronotropic deficit of 25.24±22.07beats, which was correlated to the LT (r=0.46; p<0.05). Additionally, we hypothesized that HR1, when the HR increase rate tends to rise, may be related to stroke volume (SV) time response. Literature shows that a drop on the SV increase rate occurs at approximately 40% of the VO2max, and here, we found a change in the HR response at 43.9% of the VO2max. CONCLUSION: given the two HR breakpoints, two main findings must be presented here: (1) the first breakpoint can be related to the S V time response; and (2) the second breakpoint represents a chronotropic deficit, which is related to the AT.

Lepidosaphes ussuriensis

<i>Lepidosaphes ussuriensis</i>

Extra gonad abnormally developed in the 2nd abdominal segment of the silkworm larva

Extra gonad abnormally developed in the 2nd abdominal segment of the silkworm larva

How does the ectoparasitoid wasp Euplectrus separatae (Hymenoptera: Eulophidae) recognize a suitable oviposition site on the host larva Pseudaletia separata (Lepidoptera: Noctuidae)?

The larval ectoparasitoid of Pseudaletia separata, Euplectrus separatae oviposits exclusively on the dorsolateral surface from the 3rd thoracic to the 2nd abdominal segment of the host. Larval parasitoids are well known to be exposed to risks from aggressive defense behavior when they attempt to parasitize a host. E. separatae female sting the host to inject a venom prior to oviposition. At this time the female wasp is exposed to a serious risk from aggressive host behavior. However, the female avoids the risk by moving to a specific segment of the host. The question arose as to how the female wasp recognizes the specific segments of the host. The female wasp mounted the host larva from the posterior dorsal part and moved forward on the host. The female used chemical cues to recognize the posterior part of the host body. Diethyl ether extracts from the last abdominal segments of the host were more attractive to females than extracts from the head. Motionless behavior in the host after the female wasp mounted did not induce the forward movement of the female wasp. Once the female was on the host she used crawling of the host body (peristaltic movement) as a stimulus to move forward on the host. Another key stimulus to cause the parasitoid to cease movement forward on the specific segments of the host was examined. When a host head was attached to the 3rd abdominal segment, the female wasp shifted the oviposition site adequately behind the head on the host body, suggesting that the head is used as a visual cue to pinpoint a suitable oviposition site.

Hormonal control of phase-related changes in the number of antennal sensilla in the desert locust, Schistocerca gregaria: possible involvement of [His 7]-corazonin

The effect of [His 7]-corazonin on the abundance of antennal sensilla in the desert locust, Schistocerca gregaria, was investigated to test the hypothesis that injection of this neuropeptide would mimic a crowding effect. Solitarious locusts (reared in isolation) were injected with [His 7]-corazonin at the 3rd nymphal instar and the numbers of sensilla on the 2nd, 8th and 14th antennal segments in the adult stage were compared with those for oil-injected solitarious controls or un-injected gregarious locusts (reared in group). The numbers of sensilla on these antennal segments were all reduced significantly after [His 7]-corazonin injection compared with those for oil-injected controls, but similar to the values for gregarious individuals. Among the four major types of olfactory sensilla, coeloconic, trichoid, basiconic type A and basiconic type B, [His 7]-corazonin injection influenced the abundance of all but the last type. The effect of [His 7]-corazonin injection varied with the time of injection; the earlier the injection the larger the effects on the abundance of total antennal sensilla on the 8th segment, although the way in which the injection affected the abundance varied with the sensillum type. A hypothesis explaining how crowding affects the abundance of antennal sensilla and other phase-related characteristics through changes in [His 7]-corazonin concentrations was proposed.

P0941 HIGH-RESOLUTION ESOPHAGEAL MANOMETRY (HRM) WITH TOPOGRAPHIC PLOTTING IN PRE-TERM AND TERM NEONATES

Introduction: HRM uses closely spaced recording sites and axial data interpolation to better visualize time and space relationships of pressure data. These techniques in adults and older children reveal that esophageal peristalsis is comprised of a chain of 3 contraction segments, 1 in striated muscle and 2 in the smooth-muscle region, that culminates in lower esophageal sphincter contraction. The 2nd segment (proximal smooth-muscle esophageal body) appears to be at least in part under cholinergic control and important in the peristaltic pump. HRM has not been applied to neonates to see if segmental contraction characteristics are seen in this group. Methods: HRM was used to study 5 full-term neonates (gestational age 37–41 wk; post-delivery age 0–7 d) and 7 pre-term neonates (gestational age 30–36 wk; age 3–24 d). Subjects were intubated with a 9-lumen (2.25 mm OD) perfused catheter with recording sites at 1-cm intervals, and data were acquired with a system designed specifically for HRM (MMS, Enschede, Holland). Small volume water swallows were used when possible. 3-dimensional topographic contour plots and cines of axial wave propagation were examined to detect peristaltic characteristics and recurring contraction segments. Results: The techniques were successful in each case, and peristaltic events were easily identified on topographic plots and cine review despite expected artefact - even if not clearly recognized on conventional tracings. In full-term neonates the 2nd segment was well developed and consistently present in all subjects; the 1st and 3rd were seen intermittently in 4 subjects. Complete peristaltic sequences were present in 47.6±15.3% of swallows. The 2nd segment was also consistently evident in pre-term neonates of >34 wks gestational development or 32 wks gestation plus >3wks age. Only fragments of peristalsis and no well-defined segments were seen in 2 subjects with 30–31 wks gestation plus 9–16 d age. These youngest subjects had no completed peristalses whereas the other pre-term subjects had 43.4±5.8% completed peristalses and resembled the full-term neonates (p=0.8). Conclusion: HRM with topographic plotting simplifies the identification of peristaltic events in neonates because of their similarity to the stereotypical chain of contraction segments in older subjects. The segments cannot be identified in subjects with <32 wks gestational development with <3 wks of post-delivery age, suggesting that the maturation of this process occurs near term. The prominent, early development of the 2nd contraction segment may reflect the importance of this region for its pro-clearance protective effects.

Mating behaviour of Aphidius ervi (Hymenoptera: Braconidae): The role of antennae

In the mating behaviour of Aphidius ervi Haliday the antennae play a pivotal role in partner recognition and acceptance. Mating failure was always observed when antennal contact was experimentally prevented. The male of A. ervi has filiform antennae, consisting of scape, pedicel and 18-20 cylindrical antennomeres (flagellar segments), which bear numerous types of sensory structures and, interspersed among the multiporous plate sensilla, especially on the 1th and 2nd flagellar segments, scattered pores. A secretion oozes from these pores in virgin males exposed to conspecific females. Transmission electron microscopy revealed that these pores are the external openings of integumentary glands. Behavioural and morpho-functional observations indicated that a double step sex recognition mechanism is present in A. ervi, as in other parasitic Hymenoptera. Basically, female recognition by males appears to be mediated by a volatile sex pheromone, that triggers the behavioural sequence leading to mounting. Then, the female recognizes and accepts the male after antennal contact. This is mediated by the secretion that oozes from the male antennal glands, which acts as a contact pheromone.

Development and silk production by silkworm larvae after topical application of methoprene

Juvenile hormone analogues have been tested as insect growth regulators in silkworm (Bombyx mori), seeking an increment of silk production. These chemical products, when applied in small or moderate rates, promote the extension of the last larval instar. To understand the physiologic consequences on silk production by the silkworm strain C115 x N108, the application of methoprene, a juvenile hormone analogue, was performed to evaluate its effects on larval development and silk production. Methoprene was topically applied 48h after the fourth larval ecdysis, on the dorsal integument of the 2nd thoracic segment of the insects, at seven rates between 0 and 20 ng a.i. Methoprene influenced positively the duration of the fifth instar and the weight gain of the insects. The application of 1ng methoprene resulted in the heaviest silkglands, cocoons, shell cocoons and pupae weights. Comparatively to the control, the increment on silk production (approximately 24%) by the use of 1ng methoprene was more accentuated than the corresponding negative effects on the cocooning rate (approximately 12%).

A vision on the value of the curricular physical education, leaving from imaginary and ideological perspectives

Este estudo investigou a existência de possíveis contradições ou incoerências presentes entre o discurso e a prática da Educação Física Escolar como uma disciplina curricular, considerando como a comunidade escolar percebe o desenvolvimento da Educação Física, a fim de se identificar a ideologia subjacente desta disciplina e assim, verificar o valor da mesma para a sociedade. Desta forma, trabalhou-se com as análises do conteúdo documental, relativo ao projeto MULTIEDUCAÇÃO da Secretaria Municipal de Educação do Rio de Janeiro, e do discurso dos representantes da disciplina de Educação Física de escolas municipais, bem como de outras disciplinas curriculares do 2o. segmento do ensino fundamental; dos alunos do 2o. segmento do ensino fundamental; dos pais e/ou responsáveis dos alunos participantes da pesquisa; e das direções das escolas municipais. Os resultados da pesquisa mostraram que a atuação dos profissionais de Educação Física, em sua prática pedagógica, faz com que a disciplina fique caracterizada na sociedade, por uma ideologia dominante decorrente de um imaginário, marcado por idéias contraditórias ou incoerentes entre o discurso e a prática quanto ao seu valor como disciplina curricular dentro das escolas

The role of homeotic genes in determining the segmental pattern of chordotonal organs in Drosophila.

The homeotic genes are instrumental in establishing segment-specific characteristics. In Drosophila embryos there is ample evidence that the homeotic genes are involved in establishing the differences in the pattern of sense organs between segments. The chordotonal organs are compound sense organs made up of several stretch receptive sensilla. A set of serially homologous chordotonal organs, lch3 in the 1st thoracic segment, dch3 in the 2nd and 3rd thoracic segments and lch5 in abdominal segments 1 to 7, is composed of different numbers of sensilla with different positions and orientations. Here we examine this set of sense organs and a companion set, vchA/B and veh1, in the wild type and mutants for Sexcombs reduced, Antennapedia, Ultrabithorax, and abdominal-A, using immunostaining. Mutant phenotypes indicate that Ultrabithorax and abdominal-A in particular influence the formation of these sense organs. Differential expression of abdominal-A and Ultrabithorax within compartments of individual parasegments can precisely modulate the types of sense organs that will arise from a segment.

Spinal manipulation for primary and secondary dysmenorrhoea.

Dysmenorrhoea refers to the occurrence of painful menstrual cramps of uterine origin and is a common gynaecological condition. The efficacy of medical treatments such as nonsteroidal anti-inflammatories (NSAIDs) or oral contraceptive pills (OCPs) is considerable, however the failure rate can still be as high as 20-25% and there are also a number of associated adverse effects. Many women are thus seeking alternatives to conventional medicine. One popular treatment modality is spinal manipulation therapy. There are several rationales for the use of musculoskeletal manipulation to treat dysmenorrhoea. The parasympathetic and sympathetic pelvic nerve pathways are closely associated with the spinal vertebrae, in particular the 2nd-4th sacral segments and the 10th thoracic to the 2nd lumbar segments. One hypothesis is that mechanical dysfunction in these vertebrae causes decreased spinal mobility. This could affect the sympathetic nerve supply to the blood vessels supplying the pelvic viscera, leading to dysmenorrhoea as a result of vasoconstriction. Manipulation of these vertebrae increases spinal mobility and may improve pelvic blood supply through an influence on the autonomic nerve supply to the blood vessels. Another hypothesis is that dysmenorrhoea is referred pain arising from musculoskeletal structures that share the same pelvic nerve pathways. The character of pain from musculoskeletal dysfunction can be very similar to gynecological pain and can present as cyclic pain as it can also be altered by hormonal influences associated with menstruation. To determine the safety and efficacy of spinal manipulative interventions for the treatment of primary or secondary dysmenorrhoea when compared to each other, placebo, no treatment, or other medical treatment. Electronic searches of the Cochrane Menstrual Disorders and Subfertility Group specialised register of controlled trials, CCTR, MEDLINE, EMBASE, CINAHL, Bio extracts, Psyclit and SPORTDiscus were performed to identify relevant randomised controlled trials (RCTs). The Cochrane Complementary Medicine Field's Register of controlled trials (CISCOM) was also searched. Attempts were also made to identify trials from the National Research Register, the Clinical Trial Register and the citation lists of review articles and included trials. In most cases, the first or corresponding author of each included trial was contacted for additional information. Any RCTs including spinal manipulative interventions (e.g. chiropractic, osteopathy or manipulative physiotherapy) vs each other, placebo, no treatment, or other medical treatment were considered. Exclusion criteria were: mild or infrequent dysmenorrhoea or dysmenorrhoea from an IUD. Five RCTs were identified that fulfilled the inclusion criteria for this review. Four trials involving high velocity, low amplitude manipulation (HVLA), and one involving the Toftness manipulation technique were included. Quality assessment and data extraction were performed independently by two reviewers. Meta analysis was performed using odds ratios for dichotomous outcomes and weighted mean differences for continuous outcomes. Data unsuitable for meta-analysis were reported as descriptive data and were also included for discussion. The outcome measures were pain relief or pain intensity (dichotomous, visual analogue scales, descriptive) and adverse effects. Results from the four trials of high velocity, low amplitude manipulation suggest that the technique was no more effective than sham manipulation for the treatment of dysmenorrhoea, although it was possibly more effective than no treatment. Three of the smaller trials indicated a difference in favour of HVLA, however the one trial with an adequate sample size found no difference between HVLA and sham treatment. There was no difference in adverse effects experienced by participants in the HVLA or sham treatment. The Toftness technique was shown to be more effective than sham treatment by one small trial, but no strong conclusions could be made due to the small size of the trial and other methodological considerations. Overall there is no evidence to suggest that spinal manipulation is effective in the treatment of primary and secondary dysmenorrhoea. There is no greater risk of adverse effects with spinal manipulation than there is with sham manipulation.

Nest provisioning and stinging pattern in ammophila sabulosa (hymenoptera, sphecidae): Influence of prey size

In a population of Ammophila sabulosa, hunting behaviour was followed in the field by direct observations and experimental trials. Each nest was opened immediately after its provisioning (in a non‐destructive way) in order to record prey dimensions, stings distribution (by stereomicroscopical analysis) and egg position. Subsequently, caterpillars were put back in the brood cells and the nests closed again. Distribution of stings and eggs on caterpillars appeared asymmetrical: throat, 2nd and 3rd abdominal segments were significantly more stung than the other parts; the eggs were laid significantly more often on the 3rd and 4th abdominal segments. In addition, a dimensional analysis was carried out on the A. sabulosa population and on the caterpillar prey, and a histological analysis was performed on some stung caterpillars.

Loureirophonte psammophila, a new species of Laophontidae T. Scott, 1904 (Copepoda: Harpacticoida) from Baja California, Mexico

Loureirophonte psammophila n. sp. was collected from coarse sediments of a beach near La Paz, Baja California, Mexico. The species belongs to the ‘subterranea-group’ as defined by Fiers (1993). It differs from the other representative of the group, L. subterranea (Lang, 1965) in the presence of an outer dentiform process on 2nd segment of the antennula, the chaetotaxy of P.2–P.5 and the 1-segmented male endopodite P.4. A map with the distribution of the eleven species known so far is provided.

Sudden appearance of cysts and ellobiopsid parasites on zooplankton in a Michigan lake: a potential explanation of tumor-like anomalies

Cysts on calanoid and cyclopoid copepods, previously reported as tumor-like anomalies (TLAs) in Lake Michigan and Europe, appeared briefly in Patterson Lake, a small Michigan inland lake. Cysts were rare (4% maximum) in samples collected on September 11, 1999, but appeared with high frequency on calanoid adults (49%) and cyclopoid nauplii (73%) in samples collected on October 16. By October 30, cysts were again rare (0.4% maximum). Cysts most commonly appeared on the lateral surface of the animal at the articulation of the 1st and 2nd prosomal segments and often consisted of herniated copepod tissues. Transparent, pyriform cysts co-occurred in low frequency with other types of cysts and are believed to be the trophomeres and gonomeres of ellobiopsid parasites. Histologic manifestations of cysts were diverse; herniations consisted of acellular yolk-like material and apparent host tissue, while cysts thought to be Ellobiopsis contained cells with different degrees of nuclear staining and unusual spherical bodies. Hernias were experimentally induced on live calanoid copepods by piercing the carapace with a fine needle, suggesting that ellobiopsid parasites may cause the hernias by puncturing the carapace of their hosts. Ellobiopsid parasites are common on marine crustacean zooplankton but have been recorded only once before in freshwater.

Spinal projections of cat primary afferent fibers innervating caudal facet joints.

The spinal projections of afferent fibers innervating the facet joints between caudal vertebrae were examined by the use of anterograde transport of wheat germ agglutinin-horseradish peroxidase (WGA-HRP). Experiments were performed on 5 adult cats in which spinal dorsal roots below the 2nd sacral segment (S2) on the right side were cut. Injections of WGA-HRP into the caudal facet joints gave rise to extensive cranio-caudal distribution of WGA-HRP positive products along the spinal cord, indicating that many afferent fibers innervating unilateral facet joints terminate bilaterally in laminae I-II, V-VI and X of the thoracic, lumbar, sacral and caudal spinal cord. These afferent fibers may convey a series of sensory information from the caudal facet joints to the spinal cord.

Distributed Control in Rapid Sequential Aiming Responses

The preparation and on-line control of short, rapid sequential aiming responses were studied in 3 experiments. Participants (N = 12 in Experiments 1 and 2, and 20 in Experiment 3) produced 3-segment responses (a) within self-initiation, simple reaction time (RT), and choice RT paradigms (Experiment 1); (b) without visual feedback under self-initiation conditions (Experiment 2); and (c) with and without visual feedback under simple RT conditions (Experiment 3). In all conditions in which participants initiated movement in response to an external imperative signal, the 2nd response segment was performed consistently slower than preceding and succeeding response segments. That pattern of segmental movement times was found whether or not visual feedback was available but was not evident when participants self-initiated their responses with or without visual feedback. The findings rule out the possibility that subjects' use of visual feedback is responsible for the slowing of the 2nd response segment under RT conditions and suggest that the programming of rapid sequential aiming responses can be distributed in pre- and postinitiation intervals.

A new species of &lt;i&gt;Bathymedon&lt;/i&gt; Sars, 1892 (Amphipoda: Oedicerotidae) from the western Mediterranean bathyal floor

Bathymedon longirostris sp. nov. (Amphipoda: Oedicerotidae) from the western Mediterranean bathyal suprabenthos is described. It is characterised by the well-developed rostrum; the discrete lateral lobe of head; the elongation of the peduncle segment 3 of the first antenna; the very slender propodus of the second gnathopod, which attains maximum width not at the palm angle, but at about midway along the palm margin; and by the relative length of the carpus of the foregoing limb, sub-equal to propodus. The discovery of a tiny remnant of the 2nd peduncle segment of the first antenna in the new species is commented with regard to the homologation of the peduncle segments in other members of the Family. The new taxon was captured below 593 m over muddy bottoms with pteropod shells and remains of planktonic foraminiferans. It was one of the most common amphipods in the lower slope (below ~ 1000 m), whereas in the depth range comprised between 1250 and 1859 m it was the second dominant species, representing 11.4 % of the total gammarideans captured. The area studied harbours three additional congeneric species, although their populations are mainly concentrated in the upper and middle slope. Over the bottom, adult males of the new species apparently tend to occupy higher levels beyond the water-sediment interface than the rest of demographic categories. The gut content of three individuals revealed a bulk of calcified foraminiferans, a diet in consonance with their massive mandibles. Juvenile individuals were more abundant in winter, whereas adult individuals were clearly dominant in summer, thus suggesting the biological cycle of the species follows some type of periodicity.