Bank hunters

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Bank hunters
Edged hunting spider (Dolomedes fimbriatus), female

Edged hunting spider ( Dolomedes fimbriatus ), female

Systematics
Subordination : Real spiders (Araneomorphae)
Partial order : Entelegynae
Superfamily : Lycosoidea
Family : Hunting spiders (Pisauridae)
Subfamily : Thalassiinae
Genus : Bank hunters
Scientific name
Dolomedes
Latreille , 1804

The bank hunters ( Dolomedes ) form a numerically large genus within the family of hunting spiders (Pisauridae), which in turn belongs to the order of the spiders . In the case of some species, it is a comparatively large representative of the real spiders (Araneomorphae), which live an amphibious way of life that is unique for spiders . The river bank hunter species is found almost worldwide and, according to their biology, their species prefer to inhabit bodies of water.

Common names for river bank hunters in the English-speaking world are fishing spiders , dock spiders or raft spiders , which translates as "fishing spiders ", "dock spiders" or "raft spiders".

characteristics

Male bank hunter in size comparison
Dorsal view of a male riverbank hunter

The river bank hunters reach a total body length of 6.6 to 30.4 millimeters, whereby the individuals of some species can supposedly attain a body length of 35 millimeters. It is a medium to large representative of the real spiders (Araneamorphae). With the edged hunting spider ( D. fimbriatus ) and the edged water spider ( D. plantarius ), the river bank hunters also include some of the largest spiders in Central Europe . Common to all river bank hunters is the flattened and mottled body and the long-legged shape. On the ventral surface of the body there are apparently setae ( chitinized hairs ) coated with hydrophobic (water-repellent) substances , which give the spiders their ability to lift on the water.

Dorsal detailed view of the carapace of a female river bank hunter with easily recognizable eyes

The carapace (back shield of the prosoma or front body) appears to be built fairly uniformly and is longer than wide and moderately raised. The highest point of the carapace is in the area of ​​the fovea ( apodem ). The latter is quite pronounced. The margins of the carapace are dark and the submarginal ligaments (located on the posterior margin), if present, are darkly colored and provided with short, dense setae. At the posterior (rear) edge, the carapace is slightly or completely indented. Riverside hunters, like most spiders, have eight eyes, four of which are arranged one above the other in two rows. The eyes in the top and bottom rows are approximately the same size, but those in the bottom row are smaller than those in the top. In addition, the lower row of eyes is straight or slightly arched, while the upper row is strongly curved. The median (middle) eye rectangle between the central eyes is significantly wider at the top. The basal segment of the chelicerae (jaw claws) is robustly built and the retromarginal (inside back) surface of the catch groove has four equidistant (equidistant from each other) tooth structures of identical dimensions, while there are promarginally (inside front) on each of the grooves three tooth structures. Of these, the distal (away from the center of the body) is the smallest, while the median is the largest. The third of these structures is proximal, i.e. to the middle of the body. The sternum is lancet-shaped, while it is cut off in front and tapered to a point at the back.

Lateral view of a male river bank hunter with clearly recognizable leg structures

The four pairs of legs of the river bank hunters usually have the usual length formula for spiders, descending from large to small, 4-1-2-3. The legs of the species of the genus have a yellowish or reddish brown basic color, with the dorsal (upper) surfaces occasionally showing dark longitudinal bands. The first pair of legs is provided with several macro tags. Of these, there are three on the femora (thighs) on the dorsal and three to five on the prolateral (laterally presented) and four or five on the retrolateral (laterally rear) surface, while the tibiae (splints) each have two macrosetae on the dorsal, prolateral and on retrolateral surface as well as four four ventral (bottom) pairs of macro tags. Of the Basit arsenic (base members of the tarsi or heel members) has a single pro- for three and four ventral Retrolateral and also couples Makrosetae while still additionally is a single Makroseta at the end of the ventral surface. In males of the genus, the femora of the fourth pair of legs can have tubercles (cusps) covered with setae or a collection of stiff setae ventrally. In addition, in the femora of the pedipalps (transformed extremities in the head area) of the bank hunters, the dorsal surfaces of the dorsal surfaces each have seven spines.

Rear view of a female river bank hunter with the easily recognizable drawings on the opisthosoma

The opisthosoma (abdomen) of bank hunters has a strong structure. It is also characterized by its shape and appears cut off at the front, while it is widest in the center and tapers from there towards the end. In the genus, the Oposthosoma is mostly speckled, but can also be black, white or gray striped, whereby the speckles and black stripes can appear simultaneously. On the anterior slope of the opisthosoma is a group of strong, curved setae. In the pedicle (dividing stalk between prosoma and opisthosoma), the lorum (elongated and dorsally located sclerite or hard part) is divided into four sections, two of which are arranged median and two laterally (laterally). The integument (outer body shell) of the opisthosoma is covered with a variety of setae. Some of these are feather-like in design and are mainly located in the white areas of the opisthosoma.

Genital morphological features

Lateral detail view of a male river bank hunter with missing extremities. The last one of the original two bulbs is clearly recognizable .

The male's pedipalps, including the tibia, are either as wide as they are long or rather elongated. At the tips of the tibia there is a ventrally applied apophysis (chitinized process) and a larger, stronger and retrolateral apophysis. A single globe (male sexual organ) also has the terminal (at the end) apophysis typical of hunting spiders (Pisauridae) on the tegulum (middle sclerite of the globe), which is long and slender, while its tip is trough-shaped and the distal one Part of the embolus (last sclerite of the globe). The tegulum is also designed more externally in river bank hunters, while the embolus appears to be pointed distally and ventrally. Furthermore, the embolus arises distally on the globe and is dorsoventral (back towards the abdomen). The median apophysis located there is long in shape and slender at the base. The apophysis can, however, also be oriented flat and expanded distally. As a rule, however, it is flexible.

Anterior view of a female riverbank hunter with evident epigyne

The epigyne (female sex organ) of the river bank hunters has a large triangular plate. The median septum (partition) is comparatively large and ovoid or elliptical in shape. In addition, it can be provided with large paired cavities on the flanks. In addition, the epigyne in the spiders of the genus has three presented as well as two additional lateral elevations, the latter having dark medial edges. The copulation openings are usually located on the sides of the median septum and are not infrequently protected by long, curved and lateral sclerites. The copulation channels are short in length and are curved or slightly coiled. Inside the epigyne there is a narrow and tapered bursa copulatrix (mating pouch). The spermatheks (seed pockets) are thick-walled and egg-shaped as well as comparatively small and slightly expanded. The fertilization canals are longer than the copulation canals and are often much more coiled.

Differentiation from similar spiders

Thalassius albocinctus

The river bank hunters are particularly similar to the species of the genus Thalassius , which also belongs to the family of hunting spiders (Pisauridae) , which also live an amphibious way of life, but are less common in the northern hemisphere . The bank hunters are characterized within the family by the four retromarginal teeth on the chelicerae. In addition, the beginning of a single embolus at the distal end of the respective globe and the base of an embolus with a flat, rounded extension are typical for male river bank hunters, while the short and curved copulation canals and the relatively long fertilization canals for hunting spiders are typical for female bank hunters. The chelicerae of the genus Thalassius have externally (on the outside) three teeth of unequal size and three promarginally three teeth of the same size, while in the males of the genus the tibial apophyses on the pedipalps, which are common for spiders of the superfamily of the Lycosoidea , are receded or even absent. In addition, in the males, each bulb has a large median apophysis and a fulcrum (fulcrum). In the females of the genus Thalassius , the fertilization canals are provided with either a ventral bulge or a dorsally placed loop.

In particular, the males of the river bank hunters are also very similar to those of the Tasmomedes genus, which also belongs to the same family, and can be reliably distinguished from them on the basis of the structure of the sexual organs. In the males of the genus Tasmomedes , however, the cymbium and the conductor as well as the fulcrum in the two bulbs are longer. The spermatheks in the females of the genus Tasmomedes have a different structure than those of the bank hunters.

Females of the fishing spider ( Ancylometes bogotensis )

There are also great similarities with the species of the genus Ancylometes in terms of their habitus (appearance) as well as their way of life , whereby this similarity is due in particular to the comparatively short and stocky legs of the representatives of both genera. In addition, the males of the genus, similar to those of the river bank hunters, have broad bands of either white or yellow and marginal (at the edge) bands. The species of the genus Ancylometes , which belongs to the family of the comb spiders (Ctenidae), differ from the river bank hunters in particular in the eye position that is typical for their family. Accordingly, the eyes of the spiders of the genus Ancylometes are also arranged in three rows, with the uppermost two, the middle four and the lower again two eyes.

Female of the pirate spider ( Pirata piraticus )

In addition, the river bank hunters are sometimes confused with the pirate spiders ( Pirata ), which live in the water but belong to the family of wolf spiders (Lycosidae ), which can have patterns similar to the river bank hunters. However, the pirate spiders usually stay much smaller.

Distribution and diversity of habitats

The rimmed water spider ( D. plantarius ) is one of two bank hunters found in Europe , along with the rimmed hunting spider ( D. fimbriatus ).

The river bank hunters are found on all continents with the exception of Antarctica . However, the main distribution of the genus is in the northern hemisphere . In Europe including the German-speaking area, the genus is present with two species, the gerandeten hunting spider ( D. fimbriatus ) and the gerandeten water spider ( D. plantarius ). While the Gerandete Jagdspider is often represented in parts of Central Europe , the Gerandete Water Spider has only rarely been detected. On the other hand, the latter species seems to be found in large numbers in the Netherlands .

Male shore hunter resting on a stone by a pond, found in northeast Panama .

Bank hunters prefer freshwater bodies of water as a habitat and mostly stay in its vicinity or directly on its surface. However, permanent water bodies form the habitats for river bank hunters. Despite the general preference of all riverside hunters, some species, such as D. tenebrosus or the six-point hunting spider ( D. triton ), are known to often be located far away from water.

Overall, the preference for different bodies of water varies with the different species, which can be strongly linked to specific habitats. This is particularly clear from the fact that different representatives of the river bank hunters each inhabit a river system , although the preferred microhabitats of the respective species can be different there. The definitions of the respective microhabitats are not clear and it is not uncommon for invasions within these areas by species that are not regarded as typical there. For bank hunters, the specificity of a habitat appears to be primarily determined by the size and type of the body of water and the vegetation. Regarding the latter aspect, however, it is unclear whether the respective plants that make up the vegetation or the resulting shade portion is more relevant for spider colonization.

way of life

Younger, well camouflaged river bank hunter on the bark of a tree.

Bank hunters live an amphibious way of life and often move at high speed on the surface of the water. On land, the species of the genus usually linger motionless on bridges, stones, tree trunks or other objects that offer the spiders the opportunity to camouflage themselves on them. In addition, plants protruding from the water as well as floating on it are frequent places of residence of the river bank hunters.

Bank hunters are active both day and night. However, some species, such as D. minor , are increasingly nocturnal, while the six-point hunting spider ( D. triton ) is active during the day. In addition, bank hunters can also be found under rocks by stream beds during the day .

Swimming and diving ability

Female bank hunter predominantly on the water

The high agility on the water surface is apparently made possible by setae on the ventral surface of the body coated with hydrophobic substances, which give the spiders hydrophobic (water-repellent) properties and thus keep them above water through buoyancy. Apart from locomotion on water, this ability is used to escape predators (predators) and to catch prey.

A characteristic of river bank hunters that is unusual for spiders is that they can dive completely underwater, a characteristic that is also used for flight and hunting. A riverside hunter must exert a great deal of effort to submerge, which can only be made possible, for example, by jumping from a high-lying object into the water or by stepping on a steadfast object on the surface of the water. When immersed, a sheath of air surrounds the spider's body with the tips of the longest setae and spines that determine the thickness of the air space. The river bank hunters are given a long time under water, which for some species, such as the six-point hunting spider ( D. triton ), can be an hour and a half or longer. Overall, however, bank hunters spend most of their time above water and usually only use their diving skills to escape or hunt.

The entire mechanism seems to be similar to the plastron that ensures the breathing of amphibious insects underwater. In this case, an air bubble formed by the setae would provide dissolved oxygen and dissolve carbon dioxide. In experiments in which bank hunters were sprayed with alcohol, they could not create an oxygen envelope and only remained under water for a few seconds. However, it could not be clarified whether this was actually caused by the lack of oxygen or by the effects of alcohol on the test animals.

Hunting behavior

Bank hunters, like all spiders, are predatory and kill prey primarily as ambulance hunters . The spiders do not create any nets , but hunt down prey objects freely by using the water for hunting purposes.

Hunting process

The hunting process for river bank hunters is divided into several areas. These consist of the lurking phase, the perception of prey, access and immobilization as well as consumption, while the spiders clean their bodies after they have finished eating.

Lurking for prey
Female river bank hunter lurking for prey

Bank hunters adopt a characteristic lurking manner in which the animals hold on to an object that is floating or protruding from the water with their rear pairs of legs, while the front pairs of legs are positioned on the surface of the water. The spiders often stay in this position for most of their activity time.

Tracking prey
For hunting, bank hunters use their eyes less than other sensory organs and react in particular to mechanical rather than chemical stimuli, which are perceived with the aid of the sensory hairs that are easily recognizable here.

Riverside hunters rely on mechanical as well as chemical stimuli to perceive prey, with the chemical registration of prey apparently taking place with the help of sensilla (sensory hair). In addition, bank hunters like some other spiders have both longer and straight sensillae, which serve the sense of touch , as well as shorter curved ones, which are equipped with chemoreceptors . In addition to the sensilla, bank hunters have well-trained trichobothria ( whisker hair) to perceive air movements. The perception of sounds serve as arachnids usual, the so-called (arachnids) lyriform organs on the exoskeleton of spiders. Flies that have got into the water, for example, can be perceived by river bank hunters from a distance of at least 30 to a maximum of 40 centimeters at a frequency of around 500 Hertz due to the vibrations triggered by their wing beats .

The sense of sight does not seem to be of essential importance for river bank hunters during the hunt, since even individuals of the species whose eyes were condensed could hunt without any problems. In general, there are no precise analyzes of bank hunters' eyesight. It is assumed that this is similarly well developed as in other spiders of the superfamily of the Lycosoidea .

Access and Immobilization
Female river bank hunter eating prey

If a prey, such as an insect , is located on the basis of its vibrations triggered in the water, the bank hunter rushes on it and takes it. Because of this, it is likely that the movements caused by prey both trigger the hunting instinct in riverside hunters and reveal their location. Access is usually done in one quick motion. However, if the bank hunter can no longer locate his target after the first attempt to find the target, for example because it is no longer moving for the time being, then the bank hunter will not move until the prey begins to move again.

When actually grabbing the prey, riverside hunters quickly seize prey with the pedipalps and chelicerae, whereby the latter then penetrate the prey's outer skin, as is usual with spiders, so that the riverside hunters can inject their poison into it. It is not uncommon for riverside hunters to bite prey in different places, which may serve to accelerate the killing of prey by crushing and to promote the spread of the spiders into these secreted enzymes and poison. As a result, prey the size of blowflies can be completely immobilized within a few minutes.

If a bank hunter is still busy eating another while a prey is being grabbed, or if the prey that has been caught is larger or defends itself against the attacker, the bank hunter also uses his legs to secure his hold on the prey. Spider silk is not used for either catching or securing prey that has already been caught. Larger prey animals are caught by the river bank hunters and, if the hunter is anchored to a rock, pulled onto it and consumed there. In the case of smaller prey, the spiders return to the spot that they used to lie in wait a short time after being captured, and wait there again for prey. This makes it possible for the spiders to recognize other prey animals while they are ingesting food, which can then be captured in subsequent attempts to catch them. As the need for food decreases, however, the riverside hunters' willingness to react also gradually decreases before the spiders show no more reactions to other potential prey animals that are within reach. Prey animals in the handle are dropped as soon as the need for food is completely satisfied.

consumption
Young river bank hunter, on the right the remains of a prey that has been sucked out by this prey.

While prey can be immobilized both on and under water, consumption is only possible above the surface of the water, as the digestive secretions required for sucking out prey by spiders and released by river bank hunters would be ineffective. As a result, after a successful catch under water, the animals reappear immediately after the catch and look for a stop to eat. If this is not the case, the bank hunters drift on the water and keep their prey above the surface of the water. In order to make this possible, the opisthosoma is partially held under water while the front limbs and, in particular, the pedipalps and the first pair of legs are drawn in so that the frontal area of ​​the body can be raised.

In the event of disturbances during consumption, bank hunters drop their prey and flee when they are almost completely used up or when the spiders are triggered by aversive (negative) stimuli. In the case of recently caught prey, riverside hunters can also submerge them together with them, whereby the spiders can then remain under water with the prey objects for up to 30 minutes. The condition of the prey does not change. During the ingestion of food, the prey animals are gradually processed into bolus-like objects by the riverside hunters using the chelicerae and the pedipalps . In the end, these are mostly used up and only the outer skin (in the case of captured arthropods, including their exoskeletons ) remains.

cleaning
Purifying female from Dolomedes raptor

After the consumption is complete, bank hunters usually begin with a body cleansing. The legs are stripped off individually and the pedipalps between the previously moistened chelicerae. In addition, the anterior and ventral areas of the prosoma are wiped with the help of the pedipalps and the legs are stroked, which often ends with a very fast and swinging rubbing movement of both pedipalps against each other.

There are no uniform rules among riverside hunters for exercising this behavior and it is carried out by the spiders even if no food has taken place immediately before. In addition to the actual cleaning of the body, this activity probably also serves to readjust the setae necessary for the sensory perception of the spiders.

Range of prey and its differences as well as hunting success

Close up of a female riverbank hunter with a captured arthropod

Bank hunters are opportunistic predators and do not have a specific range of prey. However, the majority of prey animals in both juvenile and adult spiders is formed by aquatic insects and the majority of prey animals within this class are in turn formed by representatives that prefer to be located either near the shore, on the surface of the water or between stones, wherever Bank hunters are most likely to be found. In experiments under laboratory conditions, bank hunters adopted a large number of invertebrates , including grasshoppers , larvae of large- winged species of the Archichauliodes genus , bees and other spiders as well as earthworms , as prey.

Tadpole of the equator-clawed frog ( Xenopus epitropicalis ) as prey of a female bank hunter

In many types of river bank hunters, the range of prey is expanded to include tadpoles and smaller fish . The successful capture of sleeper gobies from the genus Gobiomorphus with body lengths of up to four centimeters was also proven in captivity , whereby these fish also occur in the same habitats as some river bank hunters, so that the sleeper gobies mentioned may also be part of the prey spectrum of individual river bank hunters. It is also known that river bank hunters also accept dead prey which, according to current knowledge, even died two months before, although this has so far only been proven in captivity.

Bank hunter with another spider (probably another bank hunter) as prey

The success rate of hunting attempts also seems to depend on the respective prey. Blowflies, for example, have been shown to be often successfully caught by spiders, which also includes individuals within reach in flight. In contrast, attempts to catch fish are less likely to be successful. However, bank hunters do not show any decreasing ability to react even after failure and also try to catch fish several times in a row if the previous attempts to catch were unsuccessful.

Frequency of foraging

Young river bank hunter with a captured fly

The frequency of hunting activities is determined by the size of the prey. In the case of smaller prey objects, such as insects, the spiders often kill and eat several at the same time. This enables riverside hunters to cover their food needs more extensively and to hunt again at a later point in time. This can be of particular advantage in the case of nocturnal species, since significantly fewer flying insects are active when they are active. This is also generally the case during the colder seasons, although this problem can presumably be counteracted here by the slowed metabolism of the river bank hunters.

Enemies, parasites and cannibalism

Spider wasp the type cryptocheilus australis with a bank hunters of the species Dolomedes minor as prey

Above all, various birds play an important role as predators for river bank hunters . Small to medium-sized juveniles often fall victim to water striders (Gerridae) and back swimmers (Notonectidae). Shore hunters are also the prey of some objectives displacement (Pompilidae) and grave wasps (Spheciformes), while the egg sacs of spiders also susceptible to attack from other Hymenoptera are (Hymenoptera), posing as parasitoids develop. However, since cannibalism is not uncommon among river bank hunters, there is also a great danger for them from conspecifics, which can reduce entire populations of the spiders.

Life cycle

The life cycle of the banks is organized as Hunter other spinning into several phases. In the species that occur in the temperate climate zones, these are influenced by the seasons.

Courtship and mating

Males (right) and females of Dolomedes tenebrosus

The mating of the bank hunters is preceded by courtship behavior , as also occurs with other spiders of the superfamily of the Lycosoidea . The reproductive behavior of the genus has been well researched in some species, such as D. scriptus and D. vittatus , and the following analyzes are based on observations made by these two representatives. During courtship, chemical stimuli seem to play a greater role than visual ones. According to previous knowledge, courtship consists of various movements and touches of the legs and the pedipalps and begins with touching the tarsi on both sex partners, who in the meantime approach each other. The points of contact are mainly the first and partly the second pair of legs of the spiders. This phase lasts about 30 minutes and is also carried out if there are objects between the two sexual partners, such as ledges, which obstruct the optical view.

If a female replies that an approaching male is willing to mate, both sexual partners touch on the femors of the two front pairs of legs. During this introductory phase, the male's gaze is directed towards the anterior end of the female's body. Then it revolves around half the axis of the still remaining female, so that it is behind this, before the male now climbs backwards onto the female from behind, which in the meantime stretches the two front pairs of legs forward and stands high above the ground on the ends of the tarsi of the two rear pairs of legs, with the femora of the legs then aligned almost vertically. As soon as the body of the male crosses that of the female, the male lowers his body height above his sexual partner and grasps her body between the legs of the third and fourth pair and places an eyeball in the epigyne of the female. Immediately thereafter, the male releases the sperm into the female's copulatrix bursa.

It can happen that the female throws off the male, which has so far been demonstrated, for example, after the first release of the sperm. When observed, the male approached a second time and then inserted the other bulb into the epigyne before releasing its sperm. In this case, the process took just a few seconds before implementation. Thereafter, this male approached a third and a fourth time, but was refused these two times by the female and both specimens subsequently separated.

In contrast to some other spiders, such as any crested web spider (Theridiidae) or wolf spider (Lycosidae), in which the embolus breaks off during mating and remains in the bursa copulatorix of the female, this seems to be rare in riverine hunters.

Laying eggs and building cocoons

Female shore hunter with egg cocoon

Some time after mating lays a female bank hunters like for spiders usual one egg sac on a fabricated textile silk and piled structure. In the case of bank hunters, the cocoon can contain 250 to 1500 eggs, depending on the species. Like all hunting spiders (Pisauridae), bank hunters also have to take care of their brood and carry their egg cocoons attached to the chelicerae and additionally attached with an adhesive thread, with the egg cocoon being held under the body. This brood care is essential for the hatchlings to hatch.

Shortly before hatching, the female creates a brood web in which the egg cocoon is placed, following the peculiarities of the family. This web is a tent-like structure that is mostly found in low vegetation or on rocks. At the beginning the female remains on the web and at the beginning intensively guarded her egg cocoon against predators (predators). The young animals that hatch after a further period of time remain in the web for three to seven days and then become independent, spreading either through migration or via the so-called spider flight .

Growing up of young animals and life expectancy

Freshly skinned specimen of Dolomedes orion . The exuvia is still under the spider.

The young hunters the banks grow as usual for spiders over several molts approach. The process of growing up has been studied particularly well in the case of river bank hunters in the six-point hunting spider ( D. triton ) in the center of the Canadian state of Alberta . There, the growing individuals of this species need about 12 moults, with more advanced young animals undergoing additional moults at warmer temperatures in autumn. This presumably serves to delay reaching sexual maturity until the spring of the following year. The period of adolescence between the first and the ninth molting stage is identical for both sexes of the six-point hunting spider, while it takes a longer time for the female from the tenth stage than for the male. As a result, protandry occurs in this species .

  • Exuvia of a river bank hunter in detail
  • Fishing Spider Exuviae - Flickr - treegrow (1) .jpg
  • Fishing Spider Exuviae - Flickr - treegrow (2) .jpg
  • Fishing Spider Exuviae - Flickr - treegrow.jpg
Young riparian in the vegetation

The six-point hunting spider has a semivoltine (two-year) developmental period in Alberta and hibernates first in stages three to five and the second time in stages nine to 11. The development of the rinded hunting spider ( D. fimbriatus ) also appears to be longer two years. The young of the six-point hunting spider are not bound to hibernation. Young animals in the earlier stages make them dependent on the length of daylight and the temperature, while those in later stages can be influenced by thermoregulation .

Due to the protandry explained, adult males of the six-point hunting spider become sexually mature five to ten days before the females and it is not uncommon for them to meet recently adult females, which reduces the likelihood of the males being exposed to cannibalism. The phenology (activity time) ends in the male of the six-point hunting spider in Alberta in July and adult individuals of this sex usually live nine to 13 days in the adult stage. In the female of the species, phenology can range up to late August or early September in the same state, with adult individuals being active here for 25 to 31 days for the most part. In the case of the ragged hunting spider, the phenology of the male in Central Europe takes place from May and June, while that of the female begins from the same month, but can last until August.

The occasional disappearance of and the generally rather short appearance of males of the six-point hunting spider could be explained by cannibalism on the part of the females. The cannibalistic juveniles can reduce food competition by killing other juveniles of the same species.

Systematics

Graphic of a river bank hunter with a fish as prey, excerpt from The Popular science monthly (Volume 37, 1890) by an unknown author.

Classical systematics in the field of biology deals with the taxonomic (systematic) classification as well as with the biology and the nomenclature (discipline of scientific naming) of living beings, including those of river bank hunters. The type species of the genus is the gerandete hunting spider ( D. fimbriatus ).

The generic name Dolomedes is a modification of the Greek adjective dolomēdēs , which means "cunning" when translated.

Description history

In the first description of the river bank hunters, which took place in 1804 and was carried out by Pierre André Latreille , the author only referred to Charles Athanase Walckenaer with the name Les coureuses de Walckenaer ( translated from French as "the Walckenaer runners"). In 1805, Walckenaer himself converted the edged hunting spider ( D. fimbiratus ), which was previously known as Araneus fimbriatus , to this genus. This apparently corresponded to the intention of Latreille when he first described the river bank hunter species. This is also the reason why the edged hunting spider is the type species of the genus.

Inner systematics in the Nearctic river bank hunters

In 1971, James E. Carico set up a way of dealing with the relationship between the nine representatives of the river bank hunters found in the Nearctic . For this purpose, the bulbs of the males of the respective species were used as an indicator of the external systematic position to one another, whereby the basic structure of the median and tibial apophysis in particular can be viewed as helpful for this analysis. According to Carico, the structure of the tegulum and the total length of the cymbium and the tibia in the male animals of the nearctic bank hunters are also relevant.

According to Carico, the Nearctic bank hunters can probably be divided into two groups. The significantly smaller of the two groups is named after the species D. tenebrosus and includes the species D okefinokensis . The remaining seven belong to the species group of the edged hunting spider ( D. fimbriatus ), which does not occur in America itself and therefore does not belong to the species group itself. However, the genital morphological characteristics of this species are similar to those of the species belonging to this group, so that these characteristics could be used as the basis for the formation of this species group. The following cladogram illustrates the systematic relationship between the species:

  Bank hunters ( Dolomedes ) 
  Species group of D. tenebrosus 

 D. tenebrosus


   

 D. okefinokensis



  Species group of the edged hunting spider ( D. fimbriatus ) 


 D. gertschi


   

 D. scriptus



   

 D. holti


   

 D. vittatus



   

 D. albineus


   

 Six-point hunting spider ( D. triton )


   

 D. striatus


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species

The river bank hunter genus comprises 102 species including subspecies . These and their geographic distribution are:

Synonymized species

29 former species and subspecies, which last belonged to the river bank hunters, were synonymous with other species of the genus and thus lost their species status. These ancient species are:

  • D. albiclavius Bishop , 1924 - Synonymous with the six-point hunting spider ( D. triton ) under Carico, 1973.
  • D. annulatus Kishida , 1936 - Synonymized with D. sulfureus under Paik, 1969.
  • D. clercki Simon , 1937 - Synonymized with the rinded water spider ( D. plantarius ) under Renner, 1987.
  • D. elegans ( Meyer , 1790) - Synonymous with the ragged hunting spider ( D. fimbriatus ) first under Dahl, 1908 and finally accepted by Roewer and Bonnet.
  • D. fimbriatoides Bösenberg & Strand , 1906 - Synonymized with D. sulfureus under Tanikawa & Miyashita, 2008.
  • D. fulviatronotatus Bishop , 1924 - Synonymized with D. striatus under Carico, 1973.
  • D. habilis Hogg , 1906 - Synonymous with D. instabilis under Raven & Hebron, 2018.
  • D. hercules Bösenberg & Strand , 1906 - Synonymous with D. sulfureus first under Zhang, Zhu & Song 2004 and finally under Yaginuma, 1986.
  • D. hinoi Kayashima , 1952 - Synonymized with D. sulfureus under Tanikawa & Miyashita, 2008.
  • D. huttoni Hogg , 1908 - Synonymous with D. schauinslandi under Vink & Dupérré, 2010.
  • D. insurgens Chamberlin , 1924 - Synonymized with D. saganus under Zhang, Zhu & Song, 2004: 375.
  • D. italicus Thorell , 1875 - Synonymized with the edged hunting spider under Renner, 1987: 10.
  • D. japonicus Bösenberg & Strand , 1906 - Synonymized with D. sulfureus under Paik, 1969a: 29.
  • D. lateralis White , 1849 - Synonymous with D. minor under Vink & Dupérré, 2010 (older name replaced due to lack of use).
  • D. lativirgatus Kishida , 1914 - Synonymized with D. saganus under Ono & Ogata, 2018.
  • D. major Banks , 1898 - Synonymous with the six-point hunting spider under Carico, 1973.
  • D. minor White , 1849 - Synonymous with D. minor under Vink & Dupérré, 2010 (older name replaced due to lack of use).
  • D. okinavensis Kishida , 1924 - Synonymized with D. sulfureus under Ono & Ogata, 2018.
  • D. oviger Dönitz & Strand , 1906 - Synonymous with D. sulfureus under Kishida, 1936.
  • D. pallitarsis Dönitz & Strand , 1906 - Synonymized with D. saganus under Zhang, Zhu & Song, 2004.
  • D. pinicola ( Hentz , 1850) - Synonymous with D. albineus under Carico, 1973.
  • D. spatulatus Chamberlin & Ivie , 1946 - Synonymous with the six-point hunting spider under Carico, 1973.
  • D. stellatus Kishida , 1936 - Synonymized with D. japonicus under Tanikawa & Miyashita, 2008.
  • D. strandi Bonnet , 1929 - Synonymized with D. senilis under Zhang, Zhu & Song, 2004.
  • D. tridentatus Hogg , 1911 - Synonymized with Dolomedes minor under Vink & Dupérré, 2010.
  • D. trippi Hogg , 1908 - Synonymized with D. schauinslandi under Vink & Dupérré, 2010.
  • D. triton sexpunctatus Hentz , 1845 - Synonymized with the six-point hunting spider under Carico, 1973.
  • D. urinator Hentz , 1845 - Synonymous with D. vittatus under Carico, 1973.
  • D. xanthus Saito , 1939 - Synonymous with D. sulfureus under Yaginuma, 1962.

Species no longer recognized

The following 19 species and subspecies belonged to the river bank hunter genus and are now considered to be the noun dubium . The resolved types are:

  • D. aerugineus C. L. Koch , 1847 - Disbanded under Carico, 1973: 450.
  • D. chinesus duoformus Fox , 1936 - Disbanded under Zhang, Zhu & Song 2004 and again under Song, Zhu & Chen 1999.
  • D. convexus gable , 1869 - Disbanded under Carico, 1973.
  • D. cordivulva Strand , 1907 - Disbanded under Renner, 1988.
  • D. encarpatus Walckenaer , 1837 - unused after 1944.
  • D. errans Dufour , 1831 - Disbanded under Barrientos, 1978.
  • D. hastulatus Hentz , 1844 - dissolved under Carico, 1973.
  • D. iturianus Strand , 1913 - provisional designation.
  • D. kurilensis Strand , 1907 - Disbanded under Renner 1988 and Mikhailov, 1996.
  • D. lomensis Strand , 1906 - dissolved under Nentwig, 2020.
  • D. lucensis Thorell , 1873 - Disbanded under Renner, 1987.
  • D. minoratus Roewer , 1955 - Disbanded under Carico, 1976.
  • D. mirificus Walckenaer , 1837 - Disbanded under Renner Vink & Dupérré, 2010.
  • D. praeceps ( Walckenaer , 1837) - unused after 1944.
  • D. pratensis Risso , 1826 - Disbanded under Roewer, 1955.
  • D. rufus ( De Geer , 1778) - Disbanded under Carico, 1973.
  • D. saccalavus Strand , 1907 - Disbanded under Silva & Griswold, 2013.
  • D. submarginalivittatus ( Strand , 1907) - resolved under Nentwig, 2020.
  • D. tenax Hentz , 1844 - dissolved under Carico, 1973.

Species never recognized

Two types of river bank hunters did not meet the requirements for a species status when they were first described and are now considered nudum nouns . The types are:

  • D. jirisanensis Kim & Chae , 2012 - Repealed under Yoo, 2015.
  • D. sulfureus obscurivirgatus Katagiri , 1934 - repealed under Yaginuma (near Brignoli), 1983.

Synonymized genera

The following two genera were synonymous with the river bank hunters:

  • Cispiolus Roewer , 1955 - Synonymized under Blandin, 1979.
  • Teippus Chamberlin , 1924 - First in 1934 under Gertsch and again in 1973 under Carico.

Harmful effect

Since the larger river bank hunters can also catch small fish, these are considered to be minimal fish pests.

Individual evidence

  1. ↑ Charles D. Dondale, James H. Redner: The insects and arachnids of Canada, Part 17. The wolf spiders, nurseryweb spiders, and lynx spiders of Canada and Alaska, Araneae: Lycosidae, Pisauridae, and Oxyopidae . In: Research Branch Agriculture Canada Publication . tape 1856 , no. 1 . Agriculture Canada, 1990, ISBN 0-660-13628-7 , pp. 337 .
  2. ↑ a b c d e f g James Edwin Carico: The Nearctic species of the genus Dolomedes (Araneae: Pisauridae) . In: Bulletin of the Museum of Comparative Zoology . tape 144 , no. 7 . Harvard University, March 13, 1973, pp. 436 .
  3. ↑ a b c d e f g h i j k l m n o Charles D. Dondale, James H. Redner: The insects and arachnids of Canada, Part 17. The wolf spiders, nurseryweb spiders, and lynx spiders of Canada and Alaska , Araneae: Lycosidae, Pisauridae, and Oxyopidae . In: Research Branch Agriculture Canada Publication . tape 1856 , no. 1 . Agriculture Canada, 1990, ISBN 0-660-13628-7 , pp. 331 .
  4. ↑ Heiko Bellmann: The cosmos spider guide . Kosmos, 2016, ISBN 978-3-440-15521-9 , pp. 196-198 .
  5. ↑ a b c d e f g h i j k l James Edwin Carico: The Nearctic species of the genus Dolomedes (Araneae: Pisauridae) . In: Bulletin of the Museum of Comparative Zoology . tape 144 , no. 7 . Harvard University, March 13, 1973, pp. 448 .
  6. ↑ a b Martin R Filmer: Filmer's Spiders: An Identification Guide for Southern Afric . tape 2 . Penguin Random House South Africa, 2011, ISBN 978-1-4317-0182-7 , pp. 253 .
  7. ↑ Charles D. Dondale, James H. Redner: The insects and arachnids of Canada, Part 17. The wolf spiders, nurseryweb spiders, and lynx spiders of Canada and Alaska, Araneae: Lycosidae, Pisauridae, and Oxyopidae . In: Research Branch Agriculture Canada Publication . tape 1856 . Agriculture Canada, 1990, ISBN 0-660-13628-7 , pp. 331-332 .
  8. ↑ Petra Sierwald: revision of the genus Thalassius (Arachnida Araneae, Pisauridae) . In: Negotiations of the Natural Science Association in Hamburg . tape 29 , no. 1 . Hamburg January 1987, p. 59 , doi : 10.1139 / z97-200 ( researchgate.net [PDF; accessed July 26, 2021]).
  9. ↑ a b c Robert J. Raven, Wendy Hebron: A review of the Water spider family Pisauridae in Australia and New Caledonia with descriptions of four new genera and 23 new species . In: Memoirs of the Queensland Museum . tape 61 , no. 1 . Queensland Museum , 2018, ISSN  0079-8835 , p. 241 , doi : 10.17082 / j.2204-1478.60.2018.2017-06 .
  10. ^ Philipp Bertkau: Directory of Prof. Ed. van Beneden on his scientific trip to Brazil and La Plata in the years 1872-73 on his scientific trip to Brazil and La Plata on behalf of the Belgian government . In: Mémoires Couronnés et Mémoires des Savants Étrangers de l'Académie Royale des Sciences, des Lettres et des Beaux-Arts de Belgique . tape 43 , no. 1 . Brussels , S. 444 .
  11. ↑ Hubert Höfer, Antonio Domingos Brescovit: A revision of the Neotropical spider genus Ancylometes Bertkau (Araneae: Pisauridae) . In: Insect Systematics & Evolution . tape 31 , no. 3 , January 2000, p. 327 , doi : 10.1163 / 187631200X00075 ( researchgate.net [PDF; accessed August 25, 2021]).
  12. ^ Dolomedes at the British Arachnological Society, accessed June 25, 2021.
  13. ↑ a b c d e f g Natural History Museum of the Burgergemeinde Bern: World Spider Catalog - Dolomedes . Retrieved August 24, 2021.
  14. ↑ Dolomedes at the Wiki of the Arachnological Society e. V., accessed on August 25, 2021.
  15. ↑ James H. Thorp, Alan P. Covich: The Ecology and Classification of North American Freshwater Invertebrates . Elsevier , 2009, ISBN 978-0-08-088981-8 , pp. 583 .
  16. ↑ James Edwin Carico: The Nearctic species of the genus Dolomedes (Araneae: Pisauridae) . In: Bulletin of the Museum of Comparative Zoology . tape 144 , no. 7 . Harvard University, March 13, 1973, pp. 437-438 .
  17. ↑ a b c James H. Thorp, Alan P. Covich: The Ecology and Classification of North American Freshwater Invertebrates . Elsevier , 2009, ISBN 978-0-08-088981-8 , pp. 584 .
  18. ^ David S. Williams: The feeding behavior of New Zealand Dolomedes species (Araneae: Pisauridae) . tape 6 , no. 1 . Taylor & Francis , 1979, ISSN  0301-4223 , pp. 97 , doi : 10.1080 / 03014223.1979.10428352 ( scinapse.io [PDF; accessed on August 6, 2021]).
  19. ↑ Lindsay Lane: Dolomedes triton. In: Animal Diversity Web. University of Michigan , accessed August 6, 2021 .
  20. ↑ a b James Edwin Carico: The Nearctic species of the genus Dolomedes (Araneae: Pisauridae) . In: Bulletin of the Museum of Comparative Zoology . tape 144 , no. 7 . Harvard University, March 13, 1973, pp. 437 .
  21. ↑ a b David S. Williams: The feeding behavior of New Zealand Dolomedes species (Araneae: Pisauridae) . tape 6 , no. 1 . Taylor & Francis , 1979, ISSN  0301-4223 , pp. 98 , doi : 10.1080 / 03014223.1979.10428352 ( scinapse.io [PDF; accessed on August 15, 2021]).
  22. ^ David S. Williams: The feeding behavior of New Zealand Dolomedes species (Araneae: Pisauridae) . tape 6 , no. 1 . Taylor & Francis , 1979, ISSN  0301-4223 , pp. 102 , doi : 10.1080 / 03014223.1979.10428352 ( scinapse.io [PDF; accessed on August 6, 2021]).
  23. ^ David S. Williams: The feeding behavior of New Zealand Dolomedes species (Araneae: Pisauridae) . tape 6 , no. 1 . Taylor & Francis , 1979, ISSN  0301-4223 , pp. 100 , doi : 10.1080 / 03014223.1979.10428352 ( scinapse.io [PDF; accessed on August 6, 2021]).
  24. ^ David S. Williams: The feeding behavior of New Zealand Dolomedes species (Araneae: Pisauridae) . tape 6 , no. 1 . Taylor & Francis , 1979, ISSN  0301-4223 , pp. 103-104 , doi : 10.1080 / 03014223.1979.10428352 ( scinapse.io [PDF; accessed August 7, 2021]).
  25. ↑ a b c d e f g David S. Williams: The feeding behavior of New Zealand Dolomedes species (Araneae: Pisauridae) . tape 6 , no. 1 . Taylor & Francis , 1979, ISSN  0301-4223 , pp. 104 , doi : 10.1080 / 03014223.1979.10428352 ( scinapse.io [PDF; accessed on August 15, 2021]).
  26. ↑ a b c d David S. Williams: The feeding behavior of New Zealand Dolomedes species (Araneae: Pisauridae) . tape 6 , no. 1 . Taylor & Francis , 1979, ISSN  0301-4223 , pp. 99 , doi : 10.1080 / 03014223.1979.10428352 ( scinapse.io [PDF; accessed on August 15, 2021]).
  27. ↑ Hank Guarisco: The Fishing Spider Genus Dolomedes (Araneae: Pisauridae) in Kansas (=  Transactions of the Kansas Academy of Science . Volume 113 , no. 1-2 ). Fort Hays Sternberg Museum of Natural History, May 2020, p. 35 , doi : 10.1660 / 062.113.0202 .
  28. ↑ a b c d e f James H. Thorp, Alan P. Covich: The Ecology and Classification of North American Freshwater Invertebrates . Elsevier , 2009, ISBN 978-0-08-088981-8 , pp. 585 .
  29. ↑ a b c James Edwin Carico: The Nearctic species of the genus Dolomedes (Araneae: Pisauridae) . In: Bulletin of the Museum of Comparative Zoology . tape 144 , no. 7 . Harvard University, March 13, 1973, pp. 439 .
  30. ↑ James Edwin Carico: The Nearctic species of the genus Dolomedes (Araneae: Pisauridae) . In: Bulletin of the Museum of Comparative Zoology . tape 144 , no. 7 . Harvard University, March 13, 1973, pp. 439-440 .
  31. ↑ a b Heiko Bellmann: The cosmos spider guide . Kosmos, 2016, ISBN 978-3-440-15521-9 , pp. 196 .
  32. ↑ Dolomedes at Spektrum.de, accessed on August 24, 2021.
  33. ↑ James Edwin Carico: The Nearctic species of the genus Dolomedes (Araneae: Pisauridae) . In: Bulletin of the Museum of Comparative Zoology . tape 144 , no. 7 . Harvard University, March 13, 1973, pp. 443-444 .
  34. ↑ a b James Edwin Carico: The Nearctic species of the genus Dolomedes (Araneae: Pisauridae) . In: Bulletin of the Museum of Comparative Zoology . tape 144 , no. 7 . Harvard University, March 13, 1973, pp. 444 .
  35. ^ Robert Gale Breene, David Allen Dean, Martin Nyffeler, Glavis Bernard Edwards: Biology, Predation Ecology, and Significance of Spiders in Texas Cotton Ecosystems with a Key to Species (=  Texas Agriculture Experiment Station ). Texas Agricultural Experiment Station, College Station December 1993, pp. 22 .

literature

  • Robert Gale Breene, David Allen Dean, Martin Nyffeler, Glavis Bernard Edwards: Biology, Predation Ecology, and Significance of Spiders in Texas Cotton Ecosystems with a Key to Species (=  Texas Agriculture Experiment Station ). Texas Agricultural Experiment Station, College Station December 1993 (115 pp.).
  • Richard A. Bradley: Common Spiders of North America . University of California Press, 2013, ISBN 978-0-520-27488-4 (288 pp.).
  • James Edwin Carico: The Nearctic species of the genus Dolomedes (Araneae: Pisauridae) . In: Bulletin of the Museum of Comparative Zoology . tape 144 , no. 7 . Harvard University, March 13, 1973, pp. 435-488 .
  • Charles D. Dondale, James H. Redner: The insects and arachnids of Canada, Part 17. The wolf spiders, nurseryweb spiders, and lynx spiders of Canada and Alaska, Araneae: Lycosidae, Pisauridae, and Oxyopidae . In: Research Branch Agriculture Canada Publication . tape 1856 , no. 1 . Agriculture Canada, 1990, ISBN 0-660-13628-7 , pp. 1-383 .
  • Hank Guarisco: The Fishing Spider Genus Dolomedes (Araneae: Pisauridae) in Kansas (=  Transactions of the Kansas Academy of Science . Volume 113 , no. 1-2 ). Fort Hays Sternberg Museum of Natural History, May 2020, p. 35-43 , doi : 10.1660 / 062.113.0202 .
  • Robert J. Raven, Wendy Hebron: A review of the Water spider family Pisauridae in Australia and New Caledonia with descriptions of four new genera and 23 new species . In: Memoirs of the Queensland Museum . tape 61 , no. 1 . Queensland Museum , 2018, ISSN  0079-8835 , p. 233–381 , doi : 10.17082 / j.2204-1478.60.2018.2017-06 .
  • James H. Thorp, Alan P. Covich: The Ecology and Classification of North American Freshwater Invertebrates . Elsevier , 2009, ISBN 978-0-08-088981-8 (1021 pp.).
  • David S. Williams: The feeding behavior of New Zealand Dolomedes species (Araneae: Pisauridae) . tape 6 , no. 1 . Taylor & Francis , 1979, ISSN  0301-4223 , pp. 95-105 , doi : 10.1080 / 03014223.1979.10428352 ( scinapse.io [PDF; accessed August 15, 2021]).

Web links

Commons : Uferjäger ( Dolomedes )  - Collection of images, videos and audio files