Nevada Spider ID (trapdoor??)

[mattrgraham]

Hi all,

Can anyone ID this nice looking spider for me? It was found in Lincoln Co. NV in sagebrush with sandy soil. Any info on this species would be great.

Thanks,

Matt

[problemchildx]

It almost looks like a theraphosid (fangs?)

Anyone else? lol

[Pulk]

mature male?

[P. Novak]

mature male?

It almost looks like a theraphosid (fangs?)

Anyone else? lol

I'd agree with both, but I can't go much further then that. IF you can, I'd say release him where you found him. He probably doesn't have much longer to live.

[lucanidae]

I got this one:

It is a mature male in the family Mecicobothriidae, which I don't believe has a common name. The tibia of the pedipalp is swollen, which is the key characteristic to match a mature male to this family. Also it is one of the few families that fall into your range. The only genus known to fall into your range which has the abdominal pattern right is Hexura, which has only two known species, H. picea, and H. rothi. That's the best I can do....take your pick, 50/50.

[8+)]

I thought Hexura had a tergite. Am I not remembering that right, or is there a tergite in that dark area?

[lucanidae]

You are correct, but in mature males it is small and I believe it is within the dark patch at the front of the abdomen.

[Bastian Drolshagen]

hi,
it´s definetly a Mecicobothriidae (--> Fovea!)
May I ask how large that specimen is?
Check out how many spinnerets it has:
3 pairs of spinnerets --> H. picea
2 pairs of spinnerets --> H. rothi

[Brent H.]

Definitely NOT a mecicobothriid... it's a mature male Antrodiaetus montanus (family Antrodiaetidae).

[lucanidae]

I don't see the 4 pairs of sclerotized anterodorsal patches or the swelling that would be diagnostic of a male of this genus, though I am not intimately familiar with either family so I might not have the eye for the characters yet. Also, Antrodiatetus appear to have a wide space between the chelicera which thin distally, a trait this specimen doesn't seem to share.

What it really seems to come down to is whether or not the posterior lateral spinneret is long or stout. In the first picture it looks longish and tapered to me, which suggests Mecicobotheriidae, but I'm the first to admit that one picture is no substitute for the specimen and a scope.

[Brent H.]

I am intimately familiar with all North American mygalomorph genera (our lab focuses exclusively on them) and I have had a 5+ year relationship with Antrodiaetus in particular (I studied them during my dissertation research).

Antrodiaetus males usually have three darkened spots on the abdomen (sometimes four, depending if they are fused or not), the mating clasper on tibia I is very distinct for this genus (and is obvious in the photos), the spinnerets are relatively short compared to mecicobothriids (they really are much longer in the latter family), and the palpal bulbs are also distinct for this genus (it's hard to describe, but it's definitely an Antrodiaetus palp). I should also mention that the anterodorsal swelling (which is presumably homologous with the cheliceral apophysis in the three species formerly placed in the genus Atypoides) is hard to see, except for some populations of A. pacificus.

There are few records of Antrodiaetus montanus from this area (and no published records), but the coloration, form of the mating clasper, habitat description, and general distribution all match this species. The only other species that is found in similar habitats (sagebrush dominated communities) is A. hageni, but this species is only known from the Pacific Northwest and has a highly modified metatarsus I. Nearly all other species (sans A. pugnax) are found in more mesic forested areas. The genus has one of the most interesting distributions: several species in eastern North America (especially in the Ozarks and Appalachians), several in western North America (coastal ranges, Cascades, etc.), nothing from the Rockies (except for a few sky island populations of A. apachecus in NM and AZ), and a couple species from Japan (that happen to not be very closely related to each other). It was a fun group to work with, but I am starting to focus on tarantulas, especially Aphonopelma.

There may be some populations of Antrodiaetus near Ithaca, I have never spent enough time looking for them that far north.

[lucanidae]

Ahh, I definitely differ to your expertise. Thank you for all of the information. Strange that the endemic Japanese species would not be closely related to each other. Do you think this is because they speciated before the geographical barriers appeared or perhaps most of the sister species in their clade went extinct leaving gaps in the phylogeny? I wonder if the study on those exotic species was genetic or morphological or both?

[Brent H.]

Ahh, I definitely differ to your expertise. Thank you for all of the information. Strange that the endemic Japanese species would not be closely related to each other. Do you think this is because they speciated before the geographical barriers appeared or perhaps most of the sister species in their clade went extinct leaving gaps in the phylogeny? I wonder if the study on those exotic species was genetic or morphological or both?

Presumably, the lineage leading to A. roretzi became isolated from its sister lineage during the Cretaceous (they are that old) and then at some point during the Tertiary, the lineage leading to the other species (A. yesoensis) diverged, but this lineage is more closely related to the North American species than to A. roretzi. The Bering land bridge undoubtedly played an important role in shaping the present-day distribution of this genus, but I think a trans-Atlantic connection may have played a role, too. Fred Coyle used morphological data to show that the two species were not closely related; I have used DNA sequence data (from four different genes) to show that they are not closely related.

Interestingly, the trapdoor spider genus Cyclocosmia (family Ctenizidae) shows a somewhat similar distribution (Asia-North America): two species in the southeastern USA, one species in Mexico, and a handful in China/Thailand. If we are ever able to get our hands on some of the Asian material, we will test all sorts of biogeographical hypotheses with that data. The eastern Asian and eastern North American connection is well-documented in plants, so these spiders have likely shared a similar history.

[Bastian Drolshagen]

hi,
omg, didn´t know Antrodiaetidae also have a longitudinal fovea. That´s a spiderfamily I normally don´t work with.
You´re absolutely right, it IS a Antrodiaetidae - but Raven doesn´t consider the elongated apical segments of the posterior lateral spinnerets to be synapomorphically for the family Mecicobothriidae (Raven, 1985) as it has been mentioned before in this thread.

Synapomorphies for the family Mecicobothriidae are:
Fovea longitudinal; caput low, eye-tubercel distinctly raised; [...]; dorsal abdominal sclerites present.

Synapomorphies for the family Antrodiaetidae:
Fovea small closed pit or longitudinal groove; thorn spines absent from tarsi; [...]; cymbium elongated and encloses the male bulb;

(Shortened the quotations since most of the other synapomorphies mentioned in Raven, 1985 can´t be seen on the pictures above anyway)

Let me summarize what we see:
The spider on the pictures shows a fovea shaped as a longitudinal groove (way broader than at Mecicobothriidae!); a raised caput; no dorsal abdominal sclerites; cymbium not elongated (one can see that the bulb isn´t enclosed by it) and no spines on tarsi (at least what I can see).
So what else shall I say? YOU´RE RIGHT ;)

[Brent H.]

Antrodiaetids do have dorsal abdominal sclerites, they're just really small or hard to distinguish from the surrounding cuticle. They are pretty interesting spiders but have given me more headaches than you can imagine! :D

[problemchildx]

Wow, I have a lot to learn.

I barely understood half of your language, IE had to google fovea, never heard of any of these characteristics, etc.

I even learned a new word!

synapomorphies :clap:
Then again, I would only consider myself an enthusiastic hobbyist, while Brent is obviously a biology wiz, with an arachnid focus?
Makes me want to become a novice entomologist... I scurry away from hard work though. (mentally challenging that is..)

[cacoseraph]

Wow, I have a lot to learn.

I barely understood half of your language, IE had to google fovea, never heard of any of these characteristics, etc.

I even learned a new word!

synapomorphies :clap:
Then again, I would only consider myself an enthusiastic hobbyist, while Brent is obviously a biology wiz, with an arachnid focus?
Makes me want to become a novice entomologist... I scurry away from hard work though. (mentally challenging that is..)

Brent is also trying to put together a DNA based analysis of USA theraphosidae!





this is an awesome awesome thread!

[Brent H.]

Synapomorphy is just a phylogenetics term that means "shared derived character state"; synapomorphies are used to identify a lineage consisting of taxa (species, genera, families, what have you) that are more closely related to each other than they are to other groups. The character state can only be considered "derived", however, with comparison to an outgroup (a group that is presumably not a part of the lineage in question).

For example, mammary glands and hair are synapomorphies for mammals if we use a lizard as an outgroup (lizards do not have mammary glands or hair, and presumably diverged from mammals before the lineages leading to humans and kangaroos diverged from each other). Because humans and kangaroos both have mammary glands and hair, we use this information to say that they are more closely related to each other than either is to the lizard. The idea is that humans and kangaroos have these traits in common because their common ancestor also had these characteristics.

A trait can also be considered a symplesiomorphy (or shared primitive character state). For example, mammals, frogs, and lizards all have teeth, birds do not. The presence of teeth, however, cannot be used to say mammals, frogs, and lizards are more closely related to each other than any of them are to birds because the outgroup (we'll say fishes) also had teeth and is therefore a shared "primitive" trait (and we know birds and lizards are actually more closely related).

[mattrgraham]

First, thank you everyone for all the help with the spider ID. I knew this forum would figure it out.

Brent, you should have left the letters off your name. They don’t even want to argue with you anymore! So are you exclusively a spider guy now, or do you still play with scorps as well. Give a “howdy” to Mike B. for me.

Matt

[froggyman]

cool spider!

[Brent H.]

Hi Matt -

I have always wanted to work on spiders, so they are definitely my preference, but there are still a few scorp projects in the works. I am moving away from scorps in general, though, for numerous reasons.

I will pass on your message to Brewer!

Also, if you're ever in the desert south of Vegas and come across some tarantulas, let me know (I need the two species out there)!

Let me know how the dissertation project is going...

Take care,

Brent

First, thank you everyone for all the help with the spider ID. I knew this forum would figure it out.

Brent, you should have left the letters off your name. They don’t even want to argue with you anymore! So are you exclusively a spider guy now, or do you still play with scorps as well. Give a “howdy” to Mike B. for me.

Matt

[mattrgraham]

No problem Brent. How far south are you thinking? Sonoran?? I was actually down there the other night. And don't worry, I've already been keeping an eye out for T's and pedes for you, Mike, and the rest of the Bond lab. I'm really glad that Mike got into such a great group.

Matt

[Brent H.]

Matt -

Mojave Desert... you should be able to find A. iodius and A. mojave just south of Vegas (in fact, males of both species should be on the move right now). The latter species is pretty small, 2-3" legspan max, so keep me posted.

Brewer fits in well... he's eager to learn new things and has helped a lot. We're determined to get him to drink a beer, though! HA!

No problem Brent. How far south are you thinking? Sonoran?? I was actually down there the other night. And don't worry, I've already been keeping an eye out for T's and pedes for you, Mike, and the rest of the Bond lab. I'm really glad that Mike got into such a great group.

Matt