scholarly journals Ballomma, a new Afrotropical genus in the Cryptothelinae (Araneae, Zodariidae): eyes on the run

2015 ◽  
Author(s):  
Rudy Jocqué ◽  
Arnaud Henrard
Keyword(s):  
Type Species ◽  
Restricted Distribution ◽  
Median Eyes ◽  
Anterior Median

Ballomma gen. nov. is described in the zodariid subfamily Cryptothelinae. It is characterized by the pairs of adjacent anterior median eyes and anterior lateral eyes and triangular palpal tarsus in the female, the concave tegulum with thin embolus in the male. Apart from the type species B. erasmus gen. et sp. nov. (♂♀), the genus contains B. haddadi gen. et sp. nov. (♂♀), B. neethlingi gen. et sp. nov. (♂♀), and B. legala gen. et sp. nov. (♀). A key to the species is provided. The restricted distribution of the genus is discussed.

scholarly journals Revalidation of Acanthinozodium Denis, 1966 with description of three new species and discovery of a remarkable male palpal character (Araneae, Zodariidae)

2015 ◽  
Author(s):  
Rudy Jocqué ◽  
Arnaud Henrard
Keyword(s):  
New Species ◽  
Type Species ◽  
Wide Range ◽  
Three New Species ◽  
Sahel Region ◽  
Large Distribution ◽  
Median Eyes ◽  
Anterior Median

The genus name Acanthinozodium Denis, 1966 is considered available and valid, with A. spinulosum Denis, 1966 as its type species. The genus is characterized by the presence of ventral rows of long setae on the femora, large anterior median eyes and a large, dorsal, crater-like pit on the cymbium. Zodariellum Andreeva & Tyschenko, 1968 is removed from its synonymy and now only contains its type species Z. surprisum Andreeva & Tyschenko, 1968. Three new Acanthinozodium species are described: A. crateriferum sp. nov. (♂♀) from Ethiopia, A. sahelense sp. nov. (♂♀) from a wide range in the Sahel region and A. quercicola sp. nov. (♂) from Morocco. The genus appears to have a large distribution in and around the Sahara. The possible function of the cymbial pit is discussed.

scholarly journals Spectral Sensitivities of the Anterior Median Eyes of the Orb Web Spiders, Argiope Bruennichii and A. Amoena

1978 ◽  
Vol 74 (1) ◽  
pp. 47-57
Author(s):  
SHIGEKI YAMASHITA ◽  
HIDEKI TATEDA
Keyword(s):  
Dark Adaptation ◽  
Circadian Oscillation ◽  
Visual Cells ◽  
Green Cell ◽  
Intracellular Receptor ◽  
Orb Web ◽  
Blue Cell ◽  
Orb Web Spiders ◽  
Median Eyes ◽  
Anterior Median

Spectral sensitivities of the anterior median eyes of the orb web spiders, Argiope bruennichii and A. amoena have been studied by recording extracellular ERGs and intracellular receptor potentials. The anterior median eyes have three types of visual cells, with maximum sensitivities at about 360 nm (u.v. cell), 480-500 nm (blue cell) and 540 nm (green cell). The blue cells are the most sensitive and have a circadian oscillation of sensitivity. The green cells show a hypersensitivity, i.e. the sensitivity is greater for about 90 s after the cessation of illumination than during dark adaptation. Respiration is necessary for the maintenance of hypersensitivity.

scholarly journals Neodrassex, a new genus of the Leptodrassex group (Araneae, Gnaphosidae) from South America

2012 ◽  
Vol 102 (3) ◽  
pp. 343-350 ◽  
Author(s):  
Ricardo Ott
Keyword(s):  
New Species ◽  
South America ◽  
New Genus ◽  
Rio Grande ◽  
Rio Grande Do Sul ◽  
Two New Species ◽  
Black Pigmentation ◽  
Median Eyes ◽  
Anterior Median

The new genus Neodrassex is proposed to include two new species of Gnaphosidae from Brazil. Neodrassex aureus sp. nov. is described from Amazonas, Paraná and Rio Grande do Sul states, and N. iguatemi sp. nov. is described from Paraná state. Neodrassex gen. nov. is characterized by small size, pale coloration, large anterior median eyes surrounded by black pigmentation, absence of a dorsal abdominal scutum in males and by the cheliceral dentition with 2-3 teeth on the promargin and 2-4 on the retromargin. The new genus is tentatively placed at the Leptodrassex group.

Cues by which Portia fimbriata, an araneophagic jumping spider, distinguishes jumping-spider prey from other prey

2000 ◽  
Vol 203 (22) ◽  
pp. 3485-3494 ◽  
Author(s):  
D.P. Harland ◽  
R.R. Jackson
Keyword(s):  
Jumping Spider ◽  
Wide Range ◽  
Predatory Strategy ◽  
Median Eyes ◽  
Dead Prey ◽  
Anterior Median

Portia fimbriata from Queensland, Australia, is an araneophagic jumping spider (Salticidae) that includes in its predatory strategy a tactic (cryptic stalking) enabling it to prey effectively on a wide range of salticids from other genera. Optical cues used by P. fimbriata to identify the salticid species on which it most commonly preys, Jacksonoides queenslandicus, were investigated experimentally in the laboratory using odorless lures made from dead prey on which various combinations of features were altered. P. fimbriata adopted cryptic stalking only against intact salticid lures and modified lures on which the large anterior-median eyes were visible. Ordinary stalking was usually adopted when the lure did not have the anterior-median eyes visible. There was no evidence that cues from the legs of prey salticids influence the choice of stalking style of P. fimbriata, but cues from the legs do appear to influence strongly whether a prey is stalked at all. Cues from the cephalothorax and abdomen also influenced the stalking tendency, but to a lesser degree than cues from the legs. An algorithm to describe the perceptual processes of P. fimbriata when visually discriminating between salticid and non-salticid prey is discussed.

Classification and conodont-based age of the Ordovician trilobite Ellsaspis (middle Arenigian, Ville Guay, Quebec)

1984 ◽  
Vol 21 (12) ◽  
pp. 1483-1490 ◽  
Author(s):  
Ed Landing ◽  
Rolf Ludvigsen
Keyword(s):  
Continental Slope ◽  
Type Species ◽  
Baltic Basin ◽  
Canadian Association ◽  
Platform Margin ◽  
Upper Canadian ◽  
The Baltic ◽  
Anterior Median

Ellsaspis Rasetti, 1945 occurs in a thin intraclast granule and echinoderm hash packstone in continental slope facies at Ville Guay. Presence of an anterior median glabellar node and assignment of a previously unrecognized pygdium to the type species support its classification as an endymioniine trilobite. Associated conodonts of the platform margin Juanognathus biofacies, a chitinozoan, and shelf-derived orthids indicate a correlation with the middle Arenigian and upper Canadian. Association of the conodonts Prioniodus evae and P. elegans precludes a precise correlation with the condensed sequences of the Baltic Basin.

scholarly journals Dual Sensitivities of Cells in Wolf Spider Eyes at Ultraviolet and Visible Wavelengths of Light

1972 ◽  
Vol 59 (3) ◽  
pp. 247-269 ◽  
Author(s):  
Robert D. DeVoe
Keyword(s):  
Visual Pigment ◽  
Wolf Spider ◽  
Intracellular Recordings ◽  
Visual Cells ◽  
Near Ultraviolet ◽  
Lateral Eye ◽  
Visible Wavelengths ◽  
Median Eyes ◽  
Anterior Median

Intracellular recordings have been made from visual cells in principal and secondary eyes of in vitro wolf spider preparations. The responses of all cells to all wavelengths of light were graded depolarizations; no hyperpolarizations or nerve discharges were seen. Cells in a secondary eye, the anterior lateral eye, had a maximum sensitivity in the visible at 510 nm and a secondary maximum, or shoulder, of sensitivity in the near ultraviolet at 380 nm. Cells in principal eyes, the anterior median eyes, all responded maximally both in the visible at 510 nm and in the ultraviolet at 360–370 nm or less. However, there was no typical ratio of ultraviolet to visible sensitivities; the differences in log sensitivities (log UV/VIS) varied from 3.3 to -0.5. Each principal eye had a population of cells with different ratios. These populations varied with the time of the year, possibly due to changes in light upon the animals. Chromatic adaptations of cells in anterior median (but not anterior lateral) eyes resulted in small, selective changes in spectral sensitivities, and there was some facilitation of responses from cells repeatedly stimulated. It is concluded that cells of secondary eyes contain only a visual pigment absorbing maximally in the visible, while cells of principal eyes probably contain variable amounts of both this pigment and one absorbing in the ultraviolet as well.

scholarly journals Microanatomy of the anterior median eyes and its possible relation to polarized‐light reception inLycosa tarentula(Araneae, Lycosidae)

1993 ◽  
Vol 60 (4) ◽  
pp. 367-375 ◽  
Author(s):  
Jacqueline Kovoor ◽  
Arturo Muñoz Cuevas ◽  
Joaquin Ortega Escobar
Keyword(s):  
Polarized Light ◽  
Median Eyes ◽  
Anterior Median

Different functions of different eye types in the spider Cupiennius salei.

1998 ◽  
Vol 201 (2) ◽  
pp. 221-225 ◽  
Author(s):  
A Schmid
Keyword(s):  
Visual Information ◽  
Mating Behaviour ◽  
Visual Fields ◽  
Cupiennius Salei ◽  
Posterior Median ◽  
Simultaneous Choice ◽  
Target Detecting ◽  
Spider Cupiennius Salei ◽  
Median Eyes ◽  
Anterior Median

The Central American hunting spider Cupiennius salei Keys relies mainly on its mechanosensory systems during prey-catching and mating behaviour. The behavioural relevance of its eight eyes has not been studied before, although their optics and sensitivity suggest highly developed visual capabilities. The visual system was examined in a twofold simultaneous-choice experiment. Two targets were presented at a distance of 2 m from the animals, and their walking paths towards the targets were monitored. Spiders showed no preference when choosing between two identical targets, but when choosing between two different targets they strongly preferred a vertical bar to a sloping bar or a V-shaped target. By covering all eyes except the anterior median or posterior median eyes, it could be shown that the spiders were able to detect the targets using any of the eyes. Discrimination between different targets was only possible with the anterior median eyes uncovered, although the visual fields of the anterior median and posterior median eyes overlap completely. It seems most likely that the animals separate visual information in the periphery and therefore that the eyes have different functions. The posterior median eyes support a target-detecting mechanism and the anterior median eyes a target-discrimination mechanism.

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