20 February 2024

Members of the genus Latrodectus are commonly called the Widows. These spiders are in the family Theridiidae, the cobweb spiders. They spin tangled webs in dark and enclosed spaces such as under logs, in mammal burrows or even inside buildings. Females are larger than males and sometimes do eat the males after mating (though that is not always the case).

While most spiders are venomous, the venom of these spiders is considered medically significant. Their venom contains neurotoxins specific to these spiders (latrotoxins). A bite may result in localized swelling, pain, muscle cramping, vomiting and excessive sweating with symptoms lasting a few days. Thankfully, these spiders are quite rare in Minnesota and they are not aggressive. The chance of you finding one and then being bitten by it would be extremely rare. Information about treatment can be found on the Mayo System website: https://www.mayoclinic.org/diseases-conditions/spider-bites/symptoms-causes/syc-20352371.

There's some great information about this genus and distinguishing between species on BugGuide: https://bugguide.net/node/view/1999. I won't repeat all that information in detail here.

Three of the four Latrodectus known to occur in Minnesota typically arrive as stowaways in greenhouse plants, produce, furniture, etc. from locations further south. I know of no breeding populations of them in the state. The accidental species are L. geometricus/Brown Widow, L. hesperus/Western Black Widow and L. mactans/Southern Black Widow.

Latrodectus variolus or Northern Black Widow should be the only native species but this species' distribution in Minnesota is poorly understood. While I am still trying to determine its full range, its current known range is limited to the southeastern counties of Houston, Fillmore, and Winona. People living in the counties adjacent (Mower, Olmsted, Wabasha) should keep an eye out for their first county records. I have not seen this species personally but communication with those who have have found it in prairies, in gopher holes and inside of sheds.

Happy spidering!

22 January 2024

I once heard a fellow araneologist refer to the members of this genus as the "Tootsies" and have never gotten that out of my head. The Tootsies (maybe it's "Tutsies"), like other jumping spiders, rely on their acute vision to actively hunt prey during daytime hours. They are most likely to be found by using a sweep net in grasslands or shrubby habitats. Females measure up to 7.0mm while males may reach 5.5mm (Kaston, 1948).

There are four species of Tutelina found in Minnesota. T. elegans and T. similis are known from across the state and are eventually going to be found in all 87 counties (probably). T. harti is known from across the state too but is less likely to be found in the boreal forests of northern Minnesota. Lastly, T. formicaria is a state-threatened species only known from a couple of locations in Anoka County.

T. elegans (Thick-spined Jumper) and T. similis (Thin-spined Jumper) are fairly common in prairies, shrublands, bogs and other open habitats. These two species are very similar to one another but can be easily distinguished in most cases by looking at a couple of field-marks. Adult females of the two species are often metallic green to copper to purple on their bodies due to small irridescent scales (though juveniles and some adult T. similis can sometimes be grayish). Both species have white stripes running down the legs and thin white lateral edges on their carapace. The female T. elegans has a white band on the anterior of the abdomen that T. similis females lack. There are a few individuals where this band is indistinct and are best left identified to genus; this can particularly be the case with subadults. A female T. elegans: https://www.inaturalist.org/observations/83247798. A female T. similis: https://www.inaturalist.org/observations/123262523.

A close look at the males of these two species will reveal spectacular "Groucho" eyebrows (see https://bugguide.net/node/view/189639). Males can be gray to green-gray or tan but do not typically show the metallic sheen of the ladies. They are best distinguished from one another by the presence/absence of a brush of black hairs on the first pair of the legs. Male T. elegans have it: https://www.inaturalist.org/observations/189379923. Male T. similis do not: https://www.inaturalist.org/observations/5141766.

T. harti, or Hart's Jumper, is more often found in oak savannah-like habitats or cottonwood groves rather than wide open spaces. While I find them sweeping occasionally, they are more likely to be seen crawling on tree trunks with rough bark. In this species, the males are the metallic ones (blackish) and have a thick first pair of legs, each possessing a thick black brush of hairs on the tibia. The carapace often has a thick white leading edge and distinct thin, white lateral edges. Females are more nondescript (sometimes with metallic scales) but are also patterned in black and white (the flattened carapace can be a helpful hint to its identity). The abdomen is mostly white with black patches but the white scales can be rubbed off and thus abdomen pattern is variable. A male: https://www.inaturalist.org/observations/5139336 and a female: https://www.inaturalist.org/observations/6659067.

T. formicaria is a convincing ant-mimic, more so than the other members of the genus . Sexes are similar and the body can be brown to black overall. The legs have white stripes similar to other members of the genus and the white lateral edges of the carapace can curve around to the posterior as well. This species is rarely encountered across its range in eastern North America but it has also been suggested that an ant-like jumper living in the company of ants may just be more easily overlooked. They often wave their first pair of legs in the air which makes them look more like antennae than legs. One of the rare images of this species from Minnesota: https://www.inaturalist.org/observations/58075769. Also, Dick Walton has taken some excellent footage that shows how ant-like this species behaves: https://www.rkwalton.com/salticids/Tutelina_formicaria.php.

References:
Kaston, B. J. 1948. Spiders of Connecticut. Bulletin of the Connecticut State Geological and Natural History Survey 70: 1-874.

26 December 2023

The jumping spider genus Attulus is represented by four species in Minnesota. Their beauty lies in earth tones and subtle patterns and they can blend in with brickwork, the ground or rocks which often serve as their preferred habitat. They mature in spring and overwinter as juveniles. Like many jumping spiders, they are active hunters during daylight hours.

Attulus ammophilus is a non-native species that was only recently added to Minnesota's spider fauna (Hennepin County). It is native to Central Europe and Iran east into Russia but has been introduced into various parts of the U.S. and Canada; this species is slowly spreading wherever people are prevalent. This species prefers habitats with sandy soils and rocks as well as the urban environment. Males are more boldly marked than females. Example of a male: https://www.inaturalist.org/observations/141802397. Example of the very plainly marked female: https://www.inaturalist.org/observations/141802400.

Attulus fasciger or Asian Wall Jumper arrived in New York from Eastern Russia and the Orient around 1959 and spread westward, reaching St. Paul a mere 10 years later (Proszynski, 2017). It is one of the most commonly encountered jumping spiders in Minnesota due to its preferred habitat of walls of buildings both inside and outside where it is often found with another non-native jumper: Zebra Jumper (Salticus scenicus). Examination of any building during the summer months will likely yield one or two of these spiders. A typical example of one of these spiders can be found here: https://www.inaturalist.org/observations/170187126.

Attulus finschi is found from Russia into Canada and south into the mountainous western U.S. In Minnesota, it is likely to be found only in the boreal forests typical of the northern parts of the state. It is unlike many of the species in Minnesota in that it has a pale median area on both the carapace and abdomen that strongly contrasts with the darker lateral portions. It is more likely to be confused with Naphrys pulex than the other members of this genus. An example of this species can be found here: https://www.inaturalist.org/observations/55325256.

Attulus floricola is called the Flower Jumping Spider on iNaturalist. This species has a holarctic distribution. I consider this species an indicator of intact, native vegetation and it is most often collected using sweep nets in native prairie and sedge meadows. While similar to A. fasciger in its pattern and coloration, this species typically is darker and more boldly marked and it is relatively easy to distinguish between them (especially if you pay attention to habitat). Examples of this species can be found here: https://www.inaturalist.org/observations/26357449 and here: https://www.inaturalist.org/observations/130140570

Sources
Proszynski, J. 2017. Revision of the genus Sitticus Simon, 1901 s. l. (Araneae: Salticidae). Ecologica Montenegrina 10:35-50.

28 November 2023

The genus Ceraticelus is found in the family Linyphiidae which includes sheetweb spiders (subfamily Linyphiinae) and the dwarf/money spiders (subfamily Erigoninae). These are dwarf spiders and some of the smallest spider species found in Minnesota. They spin minute sheet-like webs in low vegetation or amongst the leaf litter. Adults can be found year-round and are most likely to be collected via sweep net or from sifting leaf litter (Kaston, 1948).

Most members of the genus are small (<2.0mm); females are slightly larger than males (Crosby & Bishop, 1925). The carapace is often orange to red-orange while the ocular area is often darker (black). In some of the males the ocular area is irregularly shaped and bulbous. The abdomen is variable in color but most often pale orange to cream in color. A sclerotized plate called a scutum (think armored plate) is often present and positioned toward the anterior of the abdomen on the dorsal surface. Legs are often unmarked. Members of this genus are most often confused with spiders in other genera within Linyphiiidae (Styloctetor, Ceratinopsis, Ceratinella, etc.) as well as genera within Araneidae (Hypsosinga) and Theridiidae (Thymoites).

Ceraticelus is represented by nine species in Minnesota (at this time) and caution should be taken when identifying them to species. There are no common names assigned to them. Two species are widespread and have been found more frequently than the others.

1) C. emertoni is often swept from grasslands and prairies and is known from 18 Minnesota counties at the time of this post. The male abdomen is almost entirely covered by the scutum. Both sexes are dark around the eyes and females lack a scutum. Examples of a male and female can be found here: https://www.inaturalist.org/observations/168356080.

2) C. fissiceps is also known from 18 counties at the time of this post and is often swept from the herb layer in forested ecosystems. Both sexes are dark around the eyes and both sexes also have a scutum. The ocular region of the carapace on males is bilobed and bulbous. A female can be seen here: https://www.inaturalist.org/observations/122823785. A male can be seen here: https://www.inaturalist.org/observations/126373950.

The other species are only known from 1-2 counties:

C. atriceps is similar to C. fissiceps. The males of this species also have a bilobed ocular area. A male C. atriceps collected for me by a student had a gray abdomen with an orangish scutum and gray abdomens are typical based on web-based images. In contrast, every male C. fissiceps that I've encountered had cream to orange abdomen with a darker orange scutum. Female C. atriceps lack a scutum on the dorsal surface of the abdomen but this structure is present in C. fissiceps. The epigyna are very similar between these two species though. A male is pictured here: https://bugguide.net/node/view/1672632/bgimage.

C. bryantae has a carapace that is orange-yellow with a darker eye region (Kaston, 1948). A female can be seen here: https://linepig.fieldmuseum.org/multimedia/1678182.

C. laetabilis is poorly known and there are very few pictures on the web. This species seems to differ from many members of the genus in Minnesota in that the carapace is generally darker (brown to red-brown) and the ocular area is not noticeably darker. The abdomen is paler and males have a scutum (Crosby & Bishop, 1925). See a female here: https://www.inaturalist.org/observations/26583563.

C. laetus is apparently similar to C. laetabilis in that it has a brownish carapace. Males of this species also have a scutum (Crosby & Bishop 1925). No images of this species can be found on BugGuide or iNaturalist at this time, but an image can be seen here : https://linepig.fieldmuseum.org/multimedia/1761666.

C. minutus is smaller than the other species (1.2-1.3mm) per Crosby & Bishop, 1925. Its carapace is described as brown with black reticulations (Crosby & Bishop, 1925). Very little is known about this species but habitus images of male and female can be found here: https://linepig.fieldmuseum.org/subset/habitus/381457.

C. paschalis has a yellow-orange carapace with darker eye region; the scutum on males has dusky lateral edges (Crosby & Bishop, 1925). No images of this species can be found on BugGuide or iNaturalist at this time but images of a female can be found here: https://linepig.fieldmuseum.org/multimedia/1761773.

C. similis has a yellow-orange carapace with darker eye region; males have a scutum while females do not (Crosby & Bishop, 1925). A female can be seen here: https://www.inaturalist.org/observations/46422530. A male can be seen here: https://www.inaturalist.org/observations/173792058.

SOURCES:
Crosby, C. R. & Sherman C. Bishop. 1925. Studies in New York spiders: Genera: Ceratinella and Ceraticelus. New York State Museum Bulletin, 264:1-46.

Kaston, B. J. 1948. Spiders of Connecticut. Bulletin of the Connecticut State Geological and Natural History Survey 70: 1-874.

The genus Larinioides is represented by seven species worldwide. The three species found in Minnesota (and much of North America) are also found across a wide swath of Europe and Asia and thus have Holarctic distributions. Spiders in this genus are often called the Furrow Spiders due to the pattern on their abdomens. I consider them medium to large spiders with a typical orbweaver profile and the typical vertical orb web of the family Araneidae. The underside of the abdomen is marked with what looks like a pale set of parentheses; this trait can also be found in some Araneus but can be used to distinguish Larinioides from Neoscona which has a similar pale pattern but it is broken up.

These orbweavers are nocturnal, repairing or spinning a new web each night; they rest in the center of the web while waiting for prey in the dark but retreat to nearby cover during the day (Dondale et al., 2003). Dondale et al. also indicates that the webs of these spiders typically have fewer than 20 radii extending from the center and that they mature in late spring with adults still able to be found into the Autumn (2003). Based on observations from Minnesota, these species and their webs can often be found on human structures and near water. All three species have a known distribution that suggests each should be found statewide.

Distinguishing between the three species in Minnesota can be a little tricky. Some individuals are clearly one species and not the others but some individuals have overlapping characteristics which requires some caution when identifying them. Most taxonomic keys focus on characteristics of the genitalia which are just not visible unless you are looking at preserved specimens under a microscope.

L. sclopetarius or Gray Cross Spider has longer legs than the other two species. The femurs are typically gray rather than yellowish (but some individuals can show yellow to orange). Sestakova et al. (2014) indicates that the ventral side of the femurs should have dark spots; the metatarsus on each of the hindmost legs has a dark band at its midpoint (a trait shared with L. patagiatus but not L. cornutus). The carapace is red-brown to brown and has distinct white lateral borders; it is covered with whitish hairs that are most dense in the eye region which can make it look like the anterior edge also has a white border. The abdomen can be gray to dark gray and the undulating pattern that makes the furrow is often broken about the middle of the abdomen (Dondale et al., 2003). Distinguishing between this species and L. patagiatus can be difficult with some individuals. A good example of L. sclopetarius can be seen here: https://www.inaturalist.org/observations/177988051.

L. patagiatus or Bordered Orbweaver shares traits with the other two species which lends toward confusion. The legs are shorter than in L. sclopetarius with yellow to orange femurs instead of gray; there is a dark band in the middle of the metatarsus on the hindmost leg as in L. sclopetarius. The carapace is red-brown with white lateral margins but the margins are not as distinct as they are in L. sclopetarius. The hairs on the carapace are more uniformly distributed. The furrow pattern on the abdomen has undulations that are more jagged than the rounded undulations found in L. cornutus, but sometimes that trait is difficult to judge. A good example of this species can be seen here: https://www.inaturalist.org/observations/181273676.

L. cornutus or Furrow Orbweaver also has shorter legs with femurs that are yellow to orange. This species lacks the dark band in the middle of the metatarsus on the hindleg that is found in the other two members of this genus mentioned here. The carapace is red-brown with matted white hairs that are rather uniformly distributed. The abdomen in this species is typically smooth/less hairy (sometimes glossy) and the undulating furrow marks are rounded and less jagged than those found in L. patagiatus. Distinguishing between this species and L. patagiatus can be difficult with some individuals. A good example of this species can be seen here: https://www.inaturalist.org/observations/181995990.

SOURCES:
Dondale, Charles D., James H. Redner, P. Paquin & H. W. Levi. 2003. The insects and arachnids of Canada. Part 23: The orb-weaving spiders of Canada and Alaska (Araneae: Uloboridae, Tetragnathidae, Araneidae, Theridiosomatidae). NRC Research Press, Ottawa, 371 pages.

Sestakova, A., Marusik, Y.M., and M. M. Omelko. 2014. A revision of the Holarctic genus Larinioides Caporiacco, 1934 (Araneae:Araneidae). Zootaxa, 3894 (1):061-082.

Castianeira is the only genus from the family Corinnidae that has been found in Minnesota. Many of these are mimics of hymenopterans (not just ants but also velvet ants). Their bodies are longer than wide, often with white or orange hairs. These hairs may be dense or diffuse on the carapace but often form distinct bands on the abdomen. Males possess a sclerite (think armored plate) that covers much of the dorsal surface of the abdomen; this feature is often indistinct. In females, it is much smaller in size and positioned toward the anterior. The legs are thin and often have white longitudinal stripes. These spiders are active hunters and move very quickly across the ground. They can sometimes be found under rocks, logs or other debris in appropriate habitats.

Members of this genus are often confused with spiders in the genus Sergiolus or Micaria in the family Gnaphosidae; these genera can also be brightly colored, boldly patterned and ant-like. Confusion can also occur within members of the same species of Castianeira. Individuals may vary in their base color as well as the banded pattern of hairs on the abdomen (though sometimes this is due to physical wear and not genetics). Variation within species is described more thoroughly below.

C. amoena goes by the common name of Orange Ant-Mimic Sac Spider on iNaturalist and is the most distinctive member of this genus in Minnesota. It is bright orange over much of its body with black bands on the abdomen. Its overall appearance is designed to look like a female velvet ant which is not an ant at all but rather a brightly colored ant-like wasp. The bright, contrasting pattern is designed to warn unsuspecting people that they pack quite a sting if you choose to pick one up. Looking like such an insect may provide some protection to the spider. This is a southern species that reaches the northern limit of its distribution in Minnesota. It is typically found in non-forested areas and prefers areas with rock outcroppings (Reiskind, 1969). This species is only known from Rock County in the southwestern corner of the state. Example of this species: https://bugguide.net/node/view/491173/bgimage ; https://bugguide.net/node/view/161378/bgimage.

C. cingulata or Two-banded Ant-Mimic Sac Spider has two distinct morphs (both found in Minnesota). As the common name indicates, all morphs have two pale bands on the anterior half of an abdomen that is sometimes larger toward the posterior. The femurs have dark stripes (sometimes bordered with white) on the dorsal surface as well as the femurs' sides. The "black morph" resembles a Black Carpenter Ant (Camponotus pennsylvanicus); the body is dark brown to black overall with diffuse white scales on the carapace. The carapace of the "bicolored morph" is brown toward the posterior but much darker (black) at the anterior; its abdomen is generally dark brown to black. I think this morph resembles the New York Carpenter Ant (C. novaeboracensis). This species is more common in forested ecosystems where it actively hunts for prey in the leaf litter (Reiskind, 1969). It is currently known from 17 Minnesota counties across the state. Black Morph male: https://bugguide.net/node/view/327240/bgimage Bicolored Morph female: https://bugguide.net/node/view/1371351/bgimage.

C. descripta on iNaturalist is assigned the common name of Red-spotted Ant-Mimic Sac Spider (with two other species). Perhaps a better name for it would be the Variable Red-spotted Ant-Mimic Sac Spider. Reiskind (1969) indicates that the size of the red spot on the dorsal surface of the abdomen typically gets larger as you move south and west across this species' range. The examples found by iNaturalist observers suggest that in Minnesota, males typically have a red spot that covers much of the abdomen but the size of the red spot is highly variable in females (and not related to geography). Females also show variable amounts of white hairs on their abdomen, sometimes none and other times forming transverse bands or an alternating black and white pattern. This species can be found in prairies as well as woodlands (Reiskind, 1969) which may well explain its broad distribution. It is currently known from 25 counties across the state. One other note: In Minnesota, a black spider with red on the abdomen is much more likely to be this species than a Black Widow, especially away from the southeastern Mississippi River bluff counties where widows can be rarely found.. Various forms of this species: https://www.inaturalist.org/observations/175434003 ; https://www.inaturalist.org/observations/168721899 ; https://www.inaturalist.org/observations/5211141 ; https://www.inaturalist.org/observations/130564264.

C. longipalpa or Long-palped Ant-Mimic Sac Spider. The carapace can be brown to black with diffuse to dense white hairs. The abdomen is typically darker brown to black with transverse bands of white hairs that may not reach the lateral edges and may be conjoined at the median. Their legs may have white rings and longitudinal stripes. This species can be found in prairies and well as woodlands and has the broadest distribution for any member of the genus in North America (Reiskind, 1969). In Minnesota it is known from nine counties but likely occurs statewide. Some examples of this species: https://www.inaturalist.org/observations/132485817 ; https://www.inaturalist.org/observations/131886556 ; https://www.inaturalist.org/observations/5211156.

C. trilineata has not been assigned a common name on iNaturalist and is hypothetical in its occurrence in Minnesota. It is known from Wisconsin (Reiskind, 1969). The carapace is orange-brown and shiny and the abdomen is red-brown with two bands of white hairs on the anterior half of the abdomen and a shorter band toward the posterior. Guarisco (2021) indicates that this species is similar to C. cingulata but it lacks the dark longitudinal stripes on the femurs and its legs get paler distally. A research grade example from iNaturalist: https://www.inaturalist.org/observations/144861451.

SOURCES
Guarisco, Hank. 2021. Castianeira of Kansas. Newsletter of the American Arachnological Society. Number 87.

Reiskind, Jonathan. 1969. The spider subfamily Castianeirinae of North and Central America (Araneae, Clubionidae). Bulletin of the Museum of Comparative Zoology, 138:286-325.

Spiders in the genus Phrurotimpus are currently found in the equally difficult-to-pronounce family of Phrurolithidae (they've also been assigned to Clubionidae, Liocranidae and Corinnidae in their taxonomic history). According tot the World Spider Catalog, there are 26 described species with 23 of them known from North America (the other 3 are known from China). It is possible that there are additional species waiting to be discovered or at least described. Dondale & Redner indicated they thought that the genus was in need of revision (1982) and Platnick's revision of the palustris species group is the only work that has been done since (2019).

On iNaturalist this genus of spiders goes by the common name of Antmimic Corinnine Spiders which keeps with the theme of making their name difficult to say. Dondale and Redner (1982) described them as "somewhat antlike" but I have never considered them as such and there are several more convincing ant mimics in Minnesota's spider fauna. I prefer the common name of Guardstone Spiders which is often applied to the family. That name is consistent with my experience that they are often under rocks on the ground (though not exclusively).

The overall impression of these spiders is a small, slender, fast moving ground spider (Dondale and Redner, 1982 indicates a maximum of 3.5mm). The first pair of legs is longer than the others and in males is often marked with dark patellas and tibiae bordered by a pale band on the lower tibia. Males can have a iridescent sheen to them; females (and sometimes males) have a pattern of chevrons on their abdomen.

These spiders are found in the leaf litter as well as under logs and stones in a variety of habitats. Due to their quick movement and small size, they are challenging to capture alive. They overwinter in their penultimate instar (one molt away from maturity) and mature in late spring or early summer; females attach their shiny, flat, red egg sacs to the underside of stones (Dondale & Redner, 1982). An example of their egg sac can be seen here: https://bugguide.net/node/view/309186/bgimage.

The genus Phrurotimpus in Minnesota is represented by four species.

P. alarius is only known from two counties in Minnesota: Nicollet and Mille Lacs. Kaston (1948) indicates this species has black/gray spots [bands] on legs III and IV. A female can be seen here: https://www.inaturalist.org/observations/5288693.

P. borealis is known from six counties across the state. It is known from Fillmore County in the southeast west to Blue Earth County and north to Lake of the Woods and St. Louis Counties. Female: https://www.inaturalist.org/observations/5288727 and male in alcohol: https://www.inaturalist.org/observations/82077141.

P. certus was first found in the state in 2022 and is only known from Pipestone County at this time. These individuals were very brightly colored and I knew it would be a new species of Phrurotimpus for the state when I first saw them. Female: https://www.inaturalist.org/observations/123708947 and male:https://www.inaturalist.org/observations/123262525.

P. palustris is known from three counties in the southeastern part of the state: Rice, Wabasha and Winona. There are no pictures of this species on either iNaturalist or BugGuide yet and Minnesota records were gleaned from Platnick, 2019. Platnick indicates that this species has dark bands on Legs III and IV and therefore is most likely to be confused with P. alarius.

Happy spidering!

Sources:
Dondale, C. D. & James H. Redner. 1982. The sac spider of Canada and Alaska (Araneae: Clubionidae & Anyphaenidae). Agriculture Canada, 1724:1-194.

Kaston, B. J. 1948. Spiders of Connecticut. Bulletin of the Connecticut State Geological and Natural History Survey 70: 1-874.

Platnick, Norman I. 2019. The Guardstone Spiders of the Phrurotimpus palustris Group (Araneae, Phrurolithidae). American Museum Novitates 3944:1-29.

World Spider Catalog-Phrurotimpus: https://wsc.nmbe.ch/genus/576

27 June 2023

Spiders in the family Pisauridae are commonly called the fishing spiders or nursery web spiders. Though their name suggests habitat selection near water, that is not always the case. I would classify them as large spiders (for Minneosta) and adult female Dolomedes can rival in size the Tigrosa wolf spiders mentioned in the previous post. In fact, due to their size and habits, they are often mistaken for wolf spiders. All of these species have a pretty widespread distribution in Minnesota and are commonly encountered.

Like wolf spiders, female fishing spiders can sometimes be found carrying a round egg sac with them as they traverse the landscape. Unlike the wolf spiders which attach that egg case to the spinnerets at the rear and always seem to be chased by a little round ball, the fishing spiders carry their egg sac using their chelicerae and therefore the egg sac is carried up front or under the body as they walk on their tiptoes (see https://bugguide.net/node/view/827127). Once the young have developed to a point that they are ready to leave the egg case, she finds a suitable location and creates a "nursery web". She often guards the nursery until the spiderlings have emerged and dispersed. An image of a Dolomedes striatus guarding her nest can be seen here: https://www.inaturalist.org/observations/53694419. An image of a D. tenebrosus can be seen here: https://www.inaturalist.org/observations/166245114.

In Minnesota we have 2 genera and 5 species.

The genus Dolomedes is represented by four species in Minnesota that I would divide into two different identification groups.

GROUP 1: brown-gray species
Dolomedes tenebrosus or Dark Fishing Spider is one of the most common species observers have found for the Spiders of Minnesota Project (>500 observations). This species is the most likely member of the genus to be found away from water where they often occur in wooded habitats. The W-pattern on its abdomen typically has white on the lateral portions of the W only. It also has a dark area below the eyes and a relatively unmarked carapace; the lateral edges can sometimes be white. A typical female: https://www.inaturalist.org/observations/166241082. The skinnier male: https://bugguide.net/node/view/2186027.

Dolomedes scriptus or Striped Fishing Spider is very similar in appearance to D. tenebrosus. It also has a W-pattern on the abdomen but the pattern is more bold and often has white along the entire edge of the W (not always). The carapace often has a pale midline and sometimes a lyre-like pattern as well. Some individuals may have white lateral edges to the carapace as well. In my experience, this species is more closely tied to water and I associate them with rocks and cliffs near water. A boldly marked individual: https://www.inaturalist.org/observations/124645587. A white-edged individual: https://www.inaturalist.org/observations/123923653.

GROUP 2: red-brown species
Dolomedes triton or Six-spotted Fishing Spider is commonly found near vegetated wetlands and sometimes can be found hunting for small fish and other aquatic prey on top of the water. The carapace has white sub-marginal stripes that flow into white longitudinal stripes on the abdomen. In the darker median area of the abdomen there are 6 pairs of distinct white spots (usually). A typical individual: https://www.inaturalist.org/observations/4068649.

Dolomedes striatus or Striped Fishing Spider (this is why we use those Latin names) is often found in wetlands, wet prairies and open bogs. This species is similar to D. triton. The white sub-marginal bands on the carapace are typically bolder and the red-brown median area of the carapace is darker adjacent to those white bands (unlike D. triton in which the median area is uniform in color). They also lack the distinct white spots on the abdomen. A typical female: https://www.inaturalist.org/observations/144795766. The very rare fulviatronotatus morph of this species has been found a couple of times in Minnesota and looks unlike any other member of this genus. See https://www.inaturalist.org/observations/184108563.

The last member of this family that is found in Minnesota is Pisaurina mira or American Nursery Web Spider. It is just as likely to be found in shrubs or the herb layer of a woodland as it is in a prairie and I find them often along woodland edges. This species is highly variable in its appearance and some of the drabbest individuals seem to lack any distinct markings at all. These can still be identified by this species' tendency to hold its two pairs of front legs forward and together (sometimes the rear pairs of legs are held together as well). An example of this posture can be seen here: https://www.inaturalist.org/observations/119772945

Examples of P. mira morphs:
"Red Morph": https://www.inaturalist.org/observations/54100189
"Stripe Morph": https://www.inaturalist.org/observations/91207051
"Drab Morph": https://www.inaturalist.org/observations/81516030

Happy spidering!

27 May 2023

Tigrosa means "fierce like a tiger"(Brady, 2012) and is an apt name for some of North America's largest wolf spiders. Though these are also some of the largest spiders in Minnesota, I rarely encounter them. They are longer-lived (like the Geolycosa from my previous post); females may live 2-3 years while males typically live a single season (Kaston, 1948). Both species build burrows, sometimes under rocks or logs, from which they emerge each night to hunt for prey. Both members of the genus have a pale yellow to yellow midline stripe on the carapace.

On iNaturalist, Tigrosa helluo is called the Wetland Giant Wolf Spider. As its common name suggests, it is associated with wetlands and lake edges though Kaston indicated it has been found in woodlands as well (1948). In this species, the coloration ranges from dull yellow to greenish brown (Kaston, 1948) but darker individuals do occur. The pale yellow midline extends from the anterior eyes all the way to the rear of the carapace (in most individuals). The femurs are typically dark or spotted but they lack the "tiger stripes" of T. aspersa. This species is known from 8 counties at this time from southern Minnesota north to Lake County along the Lake Superior shoreline. An example of a typical specimen can be found here: https://www.inaturalist.org/observations/122710979. A darker individual can be found here: https://www.inaturalist.org/observations/5280939.

On iNaturalist, Tigrosa aspersa is called the Woodland Giant Wolf Spider. It is the least known member of this genus in North America because it is the least encountered (Brady, 2012). This species is larger than T. helluo and was only recently added to the Minnesota spider list. The pale yellow midline is most pronounced at the anterior region of the carapace and fades toward the rear (Brady, 2012 indicates that it is only found in the ocular area, but firsthand experience suggests that trait may be variable). The femurs show pronounced "tiger stripes" of alternating, irregular black and pale yellow bands; this characteristic is absent in T. helluo. The burrow entrance may have a turret that incorporates straw or twigs (similar to Geolycosa) (Kaston, 1948). This species is only known from a single specimen found in Houston County which can be found here: https://www.inaturalist.org/observations/163305282.

Happy spidering!

Sources
Brady, Allen R. 2012. Nearctic species of the new wolf spider Tigrosa (Araneae: Lycosidae). Journal of Arachnology, 40 (2):182-208.

Kaston, B. J. 1948. Spiders of Connecticut. Bulletin of the Connecticut State Geological and Natural History Survey 70: 1-874.

Wolf spiders in the genus Geolycosa are commonly known as Burrowing Wolf Spiders. As their name implies, they spend much of their life in burrows, rarely leaving them. The relatively vertical burrows can be pretty long (170cm!) and the upper parts of the burrow are often reinforced with silk so the tunnel does not crumble inwards. Some species even have a turret that extends upward from the burrow entrance (see https://www.inaturalist.org/observations/119596857). These spiders are ambush hunters; they sit and wait near the entrance of their burrow for prey to stumble by and then rush out to grab their dinner. They mature in late summer, overwinter as adults and eggs are laid in the spring. Most species take two years to reach sexual maturity (Wallace, 1942).

Minnesota is blessed with three species of Geolycosa and since they rarely leave their burrows, very little is known about their distribution in the state.

G. missouriensis is known from 5 Minnesota counties from Kandiyohi and Hennepin north to Cass and Mille Lacs. This species prefers sandy soils with sparse vegetation, the debris of which is often incorporated into the shallow turret structure at the mouth of its burrow (Dondale & Redner, 1990). https://www.inaturalist.org/observations/135942978

G. turricola is only known from Ramsey County. It has a more easterly distribution and reaches the westernmost part of its range in Minnesota. As its name suggests, this species also has an elevated turret composed of sand, silk and vegetation at the mouth of its burrow. It also prefers sandy soils but has been found less sandy soils too. https://www.inaturalist.org/observations/142013793

G. wrighti is known from 6 Minnesota counties, primarily from Wabasha north into the Twin Cities but also from Lake of the Woods County. This species prefers bare, sandy areas and their burrows are heavily lined with silk but lack a turret (Dondale & Redner, 1990). It may be a species to look for when visiting a beach. https://www.inaturalist.org/observations/146937931

Much of the natural history information in this post was acquired from Dondale & Redner, 1990 except where noted otherwise.

•Dondale, C. D. & J. H. Redner. 1990. 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. Research Branch, Agriculture Canada, Publ. 1856: 1-383.

•Wallace, H. K. 1942. A revision of the burrowing spiders of the genus Geolycosa (Araneae: Lycosidae). American Midland Naturalist, 27: 1-62.