Posterior Lateral Eyes Research Articles

Visual pathways in the brain of the jumping spider Marpissa muscosa.

Some animals have evolved task differentiation among their eyes. A particular example is spiders, where most species have eight eyes, of which two (the principal eyes) are used for object discrimination, whereas the other three pairs (secondary eyes) detect movement. In the ctenid spider Cupiennius salei, these two eye types correspond to two visual pathways in the brain. Each eye is associated with its own first- and second-order visual neuropil. The second-order neuropils of the principal eyes are connected to the arcuate body, whereas the second-order neuropils of the secondary eyes are linked to the mushroom body. We explored the principal- and secondary eye visual pathways of the jumping spider Marpissa muscosa, in which size and visual fields of the two eye types are considerably different. We found that the connectivity of the principal eye pathway is the same as in C. salei, while there are differences in the secondary eye pathways. In M. muscosa, all secondary eyes are connected to their own first-order visual neuropils. The first-order visual neuropils of the anterior lateral and posterior lateral eyes are connected with a second-order visual neuropil each and an additional shared one (L2). In the posterior median eyes, the axons of their first-order visual neuropils project directly to the arcuate body, suggesting that the posterior median eyes do not detect movement. The L2 might function as an upstream integration center enabling faster movement decisions.

Myrmarachnine jumping spiders of the new subtribe Levieina from Papua New Guinea (Araneae, Salticidae, Myrmarachnini).

A previously unreported radiation of myrmarachnine jumping spiders from New Guinea is described, which, although having few known species, is remarkably diverse in body forms. This clade is the new subtribe Levieina, represented by seven new species in three new genera. Within Levieagen. n. are three new species, L.herbertisp. n., L.lornaesp. n., and L.francesaesp. n., all of which are unusual among the myrmarachnines in appearing as typical salticids, not antlike. Papuamyrgen. n. superficially resembles Ligonipes Karsch, 1878 or Rhombonotus L. Koch, 1879 as a compact antlike spider, but lacks their laterally-compressed palp and bears an ectal spur on the paturon of the chelicera. Two species of Papuamyrgen. n. are described, Papuamyromhifosgasp. n. and P.pandorasp. n.Agorioidesgen. n., containing A.cherubinosp. n. and A.papagenasp. n., is antlike, with the carapace sunken inwards (concave) between the posterior lateral and posterior median eyes. Phylogenetic analysis of data from the 28S, 16SND1, and COI gene regions of 29 species of myrmarachnines shows that the three new genera form a clade that is sister to the subtribe Myrmarachnina (Myrmarachne sensu lato), with the subtribe Ligonipedina less closely related.

A new species of Phonotimpus Gertsch Davis, 1940 (Araneae: Phrurolithidae) from Mexico.

The genus Phonotimpus Gertsch Davis, 1940 includes four species all known only from Mexico (World Spider Catalog 2018). P. separatus and P. eutypus were described by Gertsch Davis (1940) from San Luis Potosí and from Nuevo León, respectively. Phonotimpus pennimani and P. talquian, described by Chamé-Vázquez, Ibarra-Núñez Jiménez (2018), are the southernmost species in this genus (Chamé-Vázquez et al. 2018), and have restricted allopatric geographic distributions in Chiapas. This genus differs from other American phrurolithid genera by the following combination of characters: posterior eye row recurved, posterior median eyes closer to posterior lateral eyes than to each other, posterior median eyes smaller than posterior lateral eyes, females with dorsal scutum on the opisthosoma; palpi of males with retrolateral and dorsal tibial apophyses not joined at the base, and copulatory bulb with a conductor, embolus and embolar basal process (Gertsch Davis 1940; Penniman 1985; Chamé-Vázquez et al. 2018). In this paper, a new species of Phonotimpus is described and illustrated, based on specimens collected in soil of a pine-oak forest in the state of Mexico.

A new species of Tegenaria Latreille, 1804 (Araneae: Agelenidae) from western Iran.

Agelenidae is a species rich and globally-distributed spider family comprising 1274 species in 77 genera (World Spider Catalog 2018). In Iran, this family is currently represented by eight species in four genera (Zamani et al. 2018). Being the second largest genus of the family (after Draconarius Ovtchinnikov, 1999), Tegenaria Latreille, 1804, currently encompasses 105 species that are primarily distributed in the Palaearctic (World Spider Catalog 2018; Marusik Zamani 2015). So far, four species of this genus are known from Iran: Tegenaria domestica (Clerck, 1758) (western, northern, central and eastern Iran), T. lenkoranica (Guseinov et al., 2005) (northern Iran), T. pagana C.L. Koch, 1840 (northern Iran), and the endemic T. zamanii Marusik et Omelko, 2014 (northern Iran) (Zamani et al. 2018). Two of these species, T. lenkoranica and T. zamanii have been reported from caves (Malek-Hosseini Zamani 2017). Considering the lack of studies on this genus in Iran, many species are undoubtedly awaiting to be discovered. During the biospeleological investigations of Zagros Mountains, a new species of Tegenaria was collected in western Iran, which is described and illustrated in this paper. The specimens were photographed using an Olympus Camedia E-520 camera attached to an Olympus SZX16 stereomicroscope and digital images were prepared using "CombineZP" image stacking software. Leg ratios were measured on the dorsal side and all measurements are given in millimeters. Measurements of leg are listed as: total length (femur, patella, tibia, metatarsus, tarsus). Standard abbreviations were used for the eyes: AME, anterior median eyes; ALE, anterior lateral eyes; PME, posterior median eyes; PLE, posterior lateral eyes. The specimens will be deposited in the Manchester Museum of the University of Manchester (MMUE).

Mismatch between dietary requirements for lipid by a predator and availability of lipid in prey

Growth is an important factor in predicting an organism's overall success as an adult. Understanding how abiotic and biotic factors influence body size is key to predicting how environmental changes will impact organisms and predicting optimal behaviors under varying conditions. Food items can vary widely in nutrient content and this variation can affect growth. We tested how the quantity and macronutrient content of live prey affected the growth of juvenile jumping spiders, Phiddipus audax, using 420 spiderlings raised on one of 21 diets. In addition, we measured the nutrient content of prey from the field and compared average prey nutrient content with the diet at which spiders maximized growth. Our results show that the quantity and nutrient content of prey have significant and interacting effects on the growth of an actively hunting predator. In particular, spiders grew larger in body size (tibia/patella length and posterior lateral eye width) and were heavier on diets with higher lipid content. Yet, data on the nutrient content of prey from the field shows that most potential prey have high protein and low lipid content in their bodies. This apparent mismatch between spider nutritional requirements and prey nutrient availability likely presents a challenge to spiders seeking to maximize growth in the field. Several hypotheses for how these predators overcome this challenge to reach the large body sizes observed in the field are discussed.

Role of the different eyes in the visual odometry in the wolf spider Lycosa tarantula (Araneae, Lycosidae)

The wolf spider Lycosa tarantula returns home by means of path integration. Previous studies demonstrated: (i) that the angular component of the outbound run is measured using a polarized-light compass associated with the anterior median eyes; (ii) changes in direction of the substratum are detected by the anterior lateral eyes (ALEs); and (iii) in relation to the linear component of the outbound run, an increase of optic flow, in either the lateral or ventral fields of view, caused spiders to search for the burrow at a point nearer to the goal. However, the role of the secondary eyes [ALEs, posterior lateral eyes (PLEs) and posterior median eyes (PMEs)] in the perception of this optic flow and the importance of them for gauging the distance walked is still unknown. In this study, lateral or ventral gratings of wavelength λ=1 cm were used, with two groups of spiders in each setup: (1) PLEs+PMEs covered and (2) ALEs covered. The largest reduction in the distance walked to return to the burrow was observed with the ventral grating/ALEs covered. These results show the importance of the previously neglected ALEs for the visual behavior of these spiders. The possibility of gathering information for locomotion from the three pairs of secondary eyes in the mushroom bodies is discussed.

The Morphology And Phylogeny Of Dionychan Spiders (Araneae: Araneomorphae)

A phylogenetic analysis of the two-clawed spiders grouped in Dionycha is presented, with 166 representative species of 49 araneomorph families, scored for 393 characters documented through standardized imaging protocols. The study includes 44 outgroup representatives of the main clades of Araneomorphae, and a revision of the main morphological character systems. Novel terminology is proposed for stereotyped structures on the chelicerae, and the main types of setae and silk spigots are reviewed, summarizing their characteristics. Clear homologs of posterior book lungs are described for early instars of Filistatidae, and a novel type of respiratory structure, the epigastric median tracheae, is described for some terminals probably related with Anyphaenidae or Eutichuridae. A new type of crypsis mechanism is described for a clade of thomisids, which in addition to retaining soil particles, grow fungi on their cuticle. Generalized patterns of cheliceral setae and macrosetae are proposed as synapomorphies of the Divided Cribellum and RTA clades. Dionycha is here proposed as a member of the Oval Calamistrum clade among the lycosoid lineages, and Liocranoides, with three claws and claw tufts, is obtained as a plausible sister group of the dionychan lineage. The morphology of the claw tuft and scopula is examined in detail and scored for 14 characters highly informative for relationships. A kind of seta intermediate between tenent and plumose setae (the pseudotenent type) is found in several spider families, more often reconstructed as a derivation from true tenent setae rather than as a phylogenetic intermediate. Corinnidae is retrieved in a restricted sense, including only the subfamilies Corinninae and Castianeirinae, while the “corinnid” genera retaining the median apophysis in the copulatory bulb are not clearly affiliated to any of the established families. Miturgidae is redefined, including Zoridae as a junior synonym. The Eutichuridae is raised to family status, as well as the Trachelidae and Phrurolithidae. New synapomorphies are provided for Sparassidae, Philodromidae, and Trachelidae. Philodromidae is presented as a plausible sister group of Salticidae, and these sister to Thomisidae; an alternative resolution placing thomisids in Lycosoidea is also examined. The Oblique Median Tapetum (OMT) clade is proposed for a large group of families including gnaphosoids, trachelids, liocranids, and phrurolithids, all having the posterior median eye tapeta forming a 90° angle, used for navigation by means of the polarized light in the sky as an optical compass; prodidomines seem to have further enhanced the mechanism by incorporating the posterior lateral eyes to the system. The Teutamus group is recognized for members of the OMT clade that are usually included in Liocranidae, but not closely related to Liocranum or phrurolithids. The Claw Tuft Clasper (CTC) clade is proposed for a group of families within the OMT clade, all having a peculiar mechanism grasping the folded base of the claw tuft setae with a hook on the superior claws. The CTC clade includes Trachelidae, Phrurolithidae, and several gnaphosoids such as Ammoxenidae, Cithaeronidae, Gnaphosidae, and Prodidomidae. A remarkable syndrome involving the expansion of the anterior lateral spinnerets, often sexually dimorphic, is here reported for some Miturgidae and several members of the CTC clade, in addition to the known cases in Clubionidae and “Liocranidae.” The following genera are transferred from Miturgidae to Eutichuridae: Calamoneta, Calamopus, Cheiracanthium, Cheiramiona, Ericaella, Eutichurus, Macerio, Radulphius, Strotarchus, Summacanthium, and Tecution; Lessertina is transferred from Corinnidae to Eutichuridae. The following genera are transferred to Miturgidae: Argoctenus, Elassoctenus, Hestimodema, Hoedillus, Israzorides, Odomasta, Simonus, Thasyraea, Tuxoctenus, Voraptus, Xenoctenus, Zora, and Zoroides, from Zoridae; Odo and Paravulsor, from Ctenidae; Pseudoceto f

Visual odometry in the wolf spider Lycosa tarantula (Araneae: Lycosidae)

The wolf spider Lycosa tarantula homes using path integration. The angular component of the displacement is measured using a polarized-light compass associated with the functioning of the anterior median eyes. However, how L. tarantula estimates the linear component of the displacement was not known prior to this investigation. The ability of L. tarantula to gauge the distance walked after being displaced from its burrow was investigated using experimental channels placed in an indoor setup. Firstly, we manipulated the perception of visual stimuli by covering all the spider's eyes. Secondly, we changed the optic flow supplied by a black-and-white grating (λ=2 cm) perceived either in the lateral or in the ventral field of view. Finally, the period of the lateral or ventral grating was changed from λ=2 cm to λ=1 cm. Our results indicate that visual information contributes to distance estimation because when the spider's eyes were covered, the spiders tended to search for the burrow at very variable distances. This visual information is created by the motion of the image as the spider walks, the motion in the lateral field of view being the most important. The preference of a lateral optic flow over the ventral flow can be explained by the difference in the resolution capacity of the posterior lateral eyes and the anterior lateral eyes.

Redescription of Tagulis mystacinus (Araneae: Thomisidae) from Sri Lanka

Tagulis mystacinus Simon, 1895 from Sri Lanka is redescribed based on a pair of newly collected male and female specimens. T. mystacinus may be separated from other thomisids by the presence of very peculiar leaf-shaped macrosetae immediately posterior to anterior and posterior lateral eyes. They also may be separated by details of their genitalia.

Three new genera of jumping spider from Brazil (Araneae, Salticidae)

Nosferattus gen. nov., Capeta gen. nov. and Amatorculus gen. nov. are proposed from North and Northeastern Brazil. Due to the absence of teeth on the retromargin of the chelicerae, these genera are included within the Sitticinae, and are probably related to the genus Aillutticus Galiano, 1987, with which they share a high, broad carapace, rounded laterally behind the posterior lateral eyes, and the cephalic region slightly convex. Nosferattus is proposed to include five species: the type species Nosferattus discus sp. nov. and Nosferattus ciliatus sp. nov. from Maranhão, Nosferattus aegis sp. nov. from Tocantins, Nosferattus occultus sp. nov. from Maranhão and Ceará, and Nosferattus palmatus sp. nov. from Sergipe. Capeta and Amatorculus are both monotypic and are proposed to include Capeta tridens sp. nov., from Bahia, and Amatorculus stygius sp. nov., from Distrito Federal and São Paulo, respectively.

Spectral Sensitivity of Single Photoreceptor Cells in the Eyes of the Ctenid Spicier Cupiennius salei Keys

Intracellular recordings from photoreceptor cells of all eyes of the spider Cupiennius salei Keys reveal 3 groups of cells with spectral sensitivity maxima in the blue (480 nm). green (520 nm), and UV (340 nm), respectively. The blue and green cells show secondary peaks in the UV at 340-380 nm. In the posterior median, posterior lateral and anterior median eyes, the majority of photoreceptor cells are the blue and green cells in roughly equal numbers. In the anterior lateral eye, however, the green cells dominate. UV cells were only found in the secondary eyes and only once in each of them.

The Ocular Anomaly in a Ground Spider(Araneae: Gnaphosidae) from Japan.

The ocular anomaly in a Japanese ground spider is reported. The spider is identified with Gnaphosa primorica OVTSHARENKO, PLATNICK et SONG, 1992, described from the Russian Far East. It is recorded for the first time in Japan. The anomalous individual has only two eyes; these are regarded as the right anterior lateral and posterior lateral eyes.

Efferent optic nerve impulses in response to illumination of single eyes of orb weaving spiders

Efferent impulses in the optic nerves of the orb weaving spiders Argiope amoena and A. bruennichii in response to illumination of single eyes were examined. When light stimulation was given to the anterior median (AM) eye, the frequency of efferent optic nerve impulses increased transiently only after the offset of illumination. In contrast, when the light was given to the anterior lateral (AL), posterior median (PM) or posterior lateral (PL) eye, the frequency of efferent impulses increased transiently both after the onset and after the offset of illumination. It is suggested that the impulse generation after the onset of illumination is caused by a gradual decrease in magnitude of depolarizing photoreceptor potentials in the AL, PL and PM eyes.

Visual fields of orb web and single line web spiders of the family Uloboridae (Arachnida, Araneida)

In the family Uloboridae, web reduction is associated with changes in web monitoring posture and prosomal features. A spider must extend its first pair of legs directly forward to monitor the signal line of a reduced web. This posture is facilitated by shifts in prosomal musculature that cause reduced web uloborids to have a narrower anterior prosoma, a reduced or absent anterior eye row, and prominent posterior lateral eye tubercles. The eye tubercles and larger posterior eyes of these uloborids suggest that web reduction may also be accompanied by ocular changes that compensate for reduction of the anterior eyes by expanding the visual fields of the posterior eyes. A comparison of the visual fields of the eight-eyed, orb web species Octonoba octonaria and a four-eyed, reduced web Miagrammopes species was made to determine if this is true. Physical and optical measurements determined the visual angles of each species' eyes and the pattern of each species' visual surveillance. Despite loss of the anterior four eyes, the Miagrammopes species has a visual coverage similar to that of O. octonaria. This is due to (1) an increase in the visual field of each of the four remaining Miagrammopes eyes, accruing from an extension of the retina and an increase in the lens' rear radius of curvature, and (2) a ventral shift of each visual axis, associated with the development of an eye tubercle and an asymmetrical expansion of the retina. Miagrammopes monitor their simple webs from twigs or moss where they are vulnerable to predation. Therefore, maintenance of visual cover may enable them to detect predators in time to assume or maintain their characteristic, cryptic posture. It may also allow them to observe approaching prey and permit them to adjust web tension or prepare to jerk their webs when prey strikes.

Secondary retinae of a primitive jumping spider, Yaginumanis (Arachnida, Araneida, Salticidae)

Retinae of the secondary eyes of a primitive salticid spider, Yaginumanis sexdentatus (Yaginuma 1967) are described at the ultrastructural level. The structures of the anterior lateral, posterior lateral and posterior median eyes are identical. Receptor somata lie in the retinal cups. Each receptor bearing twin rhabdomeres is ensheated by (i) much-divided processes of non-pigmented glial cells whose somata lie distally in the retinal cups; and (ii) four processes of pigmented glial cells whose somata lie basally, below the receptive segments. Pigment granules in the latter are concentrated in the basal retina, and are not present at the level of the rhabdoms. The present findings support the placement of Yaginumanis in a newly erected Subfamily Spartaeinae by Wanless (1984), because of the likelihood of homology in the fine structural organisation of the secondary retinae of this genus and of the genus Portia.

Properties of Single Cells in Posterior Lateral Eyes of Jumping Spiders

Abstract Properties of single cells in the posterior lateral (PL) eyes of the jum ping spider Plexippus validus are described. Only one spectral class of cells was encountered and the spectra sensitivity was indistinguishable from that measured from the ERG , both peaking at ca. 535 nm. Angular sensi­ tivity (width of angular sensitivity function at the 50% level) averaged .89° ± .12°, the smallest value being .77°. Absolute sensitivity (reciprocal of the number of quanta of peak wavelength, on axis required to generate a 50% response) averaged 1.43 + 2 .5 X 1 0 -11 q-1 ,cm2·s. A ll cells studied were sensitive to the plane of polarised light. The per­ formance of receptors in the PL eyes is compared with that of receptors in the compound eyes of diurnal insects. It is concluded that the single lens eye system of spiders is in ­ herently superior in design to the insect compound eye.

Spectral sensitivities of jumping spider eyes

Spectral sensitivities of the anterior lateral, posterior lateral and anterior median eyes of the jumping spider,Menemerus confusus Boes. et Str. have been studied by recording electroretinograms (ERGs) and receptor potentials. The anterior and posterior lateral eyes have a single type of visual cell with a maximum spectral sensitivity at about 535–540 nm. The anterior median eye has four types of visual cells with maximum sensitivities at about 360, 480–500, 520–540 and 580 nm, respectively. The ERGs recorded from the optic nerve side (posterior part of the retina) were affected greatly by long wave chromatic light and those on the corneal side (anterior part of the retina) by short wave chromatic light, suggesting that each receptor layer contains a different photopigment.

The fine structure o the visual system of Lycosa (Araneae: Lycosidae). II. Primary visual centers.

Wolf spiders have four pairs of eyes distributed in three rows. The first row which lie in the frontal region of the caparace, just above the chelicera, contains four eyes: a medial pair known as the anterior medial eyes (AM eyes or principal eyes) and two smaller eyes known as the anterior lateral eyes (AL eyes). The second row which is located also in the frontal region of the prosoma consists of two big eyes. These are the posterior median eyes (PM eyes). The third row contains the posterior lateral eyes (PL eyes) which lie in the flanks of the prosomal caparace. The AL, PM and PL eyes are the so-called secondary eyes.

Observations on the fluorescence and function of spiders' eyes

Preliminary observations on spiders' eyes showed that certain eyes fluoresce in ultraviolet light and others do not. The response of these eyes to ultraviolet and visible light has been investigated to discover the relationship, if any, of eye fluorescence with eye function.In the first part of this paper it is shown that of eight spiders from families with widely differing habits, vision and behaviour, five species reacted to light fluctuations and to differences in brightness of the primary colours blue, green and red. Three species did not respond to lightand only two, S. scenicus and E. falcata, indicated a preference for blue light. It was also found that the visual sensitivity of S. secenicus extended into the ultraviolet. The second part of the paper gives the results of examination in ultraviolet light of the eyes of 40 species from 11 families. Spiders with poor sight and a preference for shade generally showed a strong fluorescence of all eyes. The anterior median and lateral eyes of those species with good sight fluoresced only weakly or not at all, whereas the posterior median and lateral eyes ofthese spiders fluoresced brightly.Freshly cut frozen sections of the eyes of two selected species, S. scenicus with good sight and C. similis with poor sight, were examined with the fluorescence, phase and polarizing microscopes. The localization of the fluorescence in these eyes is described and a fluorescent substance, common to all the spiders, was found in the lens of the eyes of most species examined.Additional information on the structure of the cornea and lens was also revealed by phase and polarized light microscopy.The results suggest that spiders' eyes respond to light in different ways and the fluorescent substance present in the lens of the eyes is related to eye function.

New Nebraska Spiders.*

Recent collections of spiders in the state of Nebraska have revealed the following new species. Brachybothrium lincolnianum n. sp. Male. In life, black or fuscous in color, the venter lighter than the dorsum and the carapace somewhat lighter than the abdomen. In alcohol, this color changes to a yellow or brown, the cephalothorax then being yellowish and the abdomen darker, a soft brown or tan. Eye area twice as wide as long; anterior median eyes separated from each other by an interval equal to more than twice the diameter of one of them and from the anterior lateral eyes by a space only slightly greater; the latter have a diameter two and one-half times that of the former. The posterior median eyes are as far apart as are the anterior lateral eyes, while the posterior lateral eye, the posterior median eye, and the anterior median eye of each side are in a row and form almost a straight line. The posterior lateral eyes have a diameter two-thirds as great as that of the posterior median eyes, while the posterior median eyes have a diameter about three-fourths that of the anterior lateral eyes, which are by far the largest eyes; posterior row slightly longer than the anterior.