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Photo#1776731
Pretty green, red, and yellow spider - Diaea livens

Pretty green, red, and yellow spider - Diaea livens
Pipeline Road, Henry Cowell State Park, Santa Cruz County, California, USA
February 4, 2020
Beautiful spider found (by Kathryn) on stem of a tall, lanky, airy coyote brush (Baccharis pilularis). Habitat was a sunny opening in mixed redwood/oak/madrone coastal forest.

At this point I'm too much of a novice with spider taxonomy to have any ideas on the family/genus ID for this beauty...but I trust BugGuide brethren and/or others will be able to provide guidance ;-)

[For full-resolution image, click this link, then click the image on the screen once more.]

Images of this individual: tag all
Pretty green, red, and yellow spider - Diaea livens Pretty green, red, and yellow spider - Diaea livens Pretty green, red, and yellow spider - Diaea livens Pretty green, red, and yellow spider - Diaea livens

Moved upon agreement
Moved from Spiders.

How about

Lovely!

 
Yes...I think that's it :-)
Thanks J & J for (yet again) pointing me in the right direction!

D. livens appears in two posts by Scott Peden from Big Basin State Park, not far from where my photos were taken and with similar habitat:

   

...and the species also appears in three posts by Ken Schneider from a bit further north (but still in the Santa Cruz Mountains area):

     

Happily, Ken's specimen IDs were verified by both arachnologist Darrell Ubick at the Cal. Acad. of Sciences and R. J. Adams, author of a book on spiders of the Pacific states.

And it's always a treat to find that Alice has posted fine-detail photos of a taxon one's trying to learn about:

   

Alice and others also have additional photos of D. livens at this Flickr search link (though some images there are not claimed to be D. livens, and lack expert-verified IDs).

Taken together, all those photos suggest substantial variation in color-patterning for D. livens...particularly on the dorsum of the abdomen. It seems some of the variation may be associated with different developmental stages as well as sexual dimorphism. And crab spiders are said to be able to slowly change their color to adapt to different backgrounds, so perhaps that may also contribute to perceived variation? At any rate, in all the photos cited the cephalothorax and legs are (at least mostly) pale-green...and critical characters of the 8 eyes agree in terms of their positions, sizes, and the pale white-to-yellow color of their raised ocellar tubercles. These characters are in accord with the descriptions and other info on D. livens and its synonyms that I've been able to find. [Note: I've added synonyms, references, links, and commentary to the info page.]

Note that presently D. livens is one of only two species of Diaea recorded in United States (text search using "USA" on the World Spider Catalog Diaea listings page here). The other species, D. seminole is recorded from Florida only, while D. livens is recorded from California only (see 4th entry here). California members of the species were initially described in 1896 under the name D. pictilis, and though another CA species was described in 1908 by Coolidge, that was eventually synonymized within a slightly more variable notion of D. pictilis. But subsequent discoveries and study of european specimens in the 1980's & 90's suggested D. pictilis should be considered a synonym within a yet slightly more variable species conception of D. livens...which was originally described by Simon in 1876 based on material from southeastern France. In recent decades D. livens has been found in many scattered localities throughout 20 countries in southern & central Europe, from Spain east to Iran...but is nevertheless characterized as "very rarely found" throughout the region (see here). Based, presumably, on its widespread presence in Europe, the World Spider Catalog considers the California populations as introduced here from Europe.

In addition to the visual match of the pale-green legs & cephalothorax, and the eye characters...running my photos through the key to genera of Thomasidae on pg. 36 of Schick(1965) also leads to Diaea. There are only 3 keying steps:

1) At couplet 1, the front legs are more than twice as long as the 3rd & 4th pairs of legs (which initially didn't appear to be the case to my eyes, but I verified by measuring in Photoshop! ;-)
2) Next, at couplet 10, note that the foreleg has two "proapical spiniforms" (cf. Fig. 5 on pg 16) at the tip of the basitarsus (= "metatarsus", see figure here). This is best seen in the full-size 2nd photo and 3rd photo of my series.
3) Finally, the most technical and difficult to discern key character is at couplet 11...namely: of the two setae "A1" and A2" lying laterad to the outer posterior eye, the inner seta ("A1") is shorter than the outer seta ("A2"). This can (barely) be seen in the full-size 2nd photo to the right of the spider's right eye (which is on the left in the upside-down oriented photo ;-).

Incidently, in accord with the additional characters mentioned in Schick's couplet 11 for Diaea, I think (but am not completely convinced) that my photos suggest the absence of setae labelled "X" in Fig. 2 on pg. 9 (which are a medial pair of rearward pointing seta at the widest point of the carapace)...and also the prominence of the seta "T5". But those characters will typically be very difficult-to-impossible to make out in most (non focus-stacked) field photos!

Thus, since there's only one CA species, we arrive at D. livens.