Photos / Sounds

What

Ground Crab Spiders Genus Xysticus

Observer

arnel

Date

January 12, 2020 10:17 AM PST

Description

I discovered this Crab Spider (Xysticus sp.), in a cluster of unopened flowers on a California Bay Laurel (Umbellularia californica) at Alum Rock Park in San Jose, CA. This California Bay Laurel was located along the banks of Penitencia Creek, which runs through the center of Alum Rock Park. I took 5 shots from as many different angles as the spider would allow, to help facilitate with its identification. I shall refer to these shots in series order below, with the first shot of the series being Shot 1, the second shot of the series being Shot 2, etc.

I could tell that the spider in my photograph was a crab spider because of its stocky build and laterigrade forelegs (see especially Shots 2 and 5). The laterigrade forelegs allow it to spread its forelegs at a 90 degree angle with respect to the main axis of its body. In northern California, there are three main categories of crab spiders: the giant crab spiders of the family Sparassidae, the running crab spiders of the family Philodromidae, and the regular crab spiders of the family Thomisidae.

Giant Crab Spiders are dorsoventrally flattened, which is not the case for my spider. Their legs are also quite long and spindly, much longer than those of my spider Therefore the Giant Crab Spiders in Sparassidae can be eliminated from consideration.

Running Crab Spiders are characterized by having a pair of forelegs that are shorter than the pair of legs immediately behind them. From Shot 2, it is clear that, for my spider, this is not the case (i.e., its forelegs are longer than the pair of legs behind them). Therefore the Running Crab Spiders in Philodromidae can also be eliminated from consideration.

This leaves us with the regular Crab Spiders in the family Thomisidae. There are two major categories for the Thomisidae-type Crab Spiders: those that are brightly colored, and those that are not. My spider is not brightly colored at all, so about half of the genera in Thomisidae can be eliminated. This leaves us with the genera Xysticus, Ozyptila, Tmarus, and Coriarachnae.

Tmarus can be eliminated because spiders in this genus have an elongated body shape that makes them resemble leaf buds. Coriarachne can also be eliminated because the carapace of these spiders is highly flattened. This leaves us with the two remaining genera, Xysticus and Ozyptila. These two genera can be differentiated by looking at the dimensions of their femurs. Xysticus-type spiders have long femurs (length about 4 times their thickness), whereas Ozyptila-type spiders have shorter, thicker femurs (length about 2 times their thickness). After examining the femurs of this spider’s legs, their lengths appear to be 4 times their thickness, so this is a Xysticus-type spider.

Not being an arachnologist, it is entirely possible that my analysis is off, so I consider this identification to be tentative. Suggestions and corrections are welcome!

Overall Dimensions:
Spider was approximately 7mm long by 3mm wide.

References:
1) Adams, R.J. (2014). Field Guide to the Spiders of California and the Pacific Coast States. Befekeley, CA: University of California Press. See especially the descriptions of the Sparassidade, Phildromidae, and Thomisidae families on pp. 180-195.

Ground Crab Spiders - Photo (c) Valter Jacinto, all rights reserved
mokennon's ID: Ground Crab Spiders (Genus Xysticus)
Added on January 21, 2020.
Supporting
Isotoma delta - Photo (c) PerkPenn, some rights reserved (CC BY-NC-ND)
mokennon's ID: Isotoma delta, a member of Elongate-bodied Springtails (Order Entomobryomorpha)
Added on January 13, 2020.
Supporting

Photos / Sounds

What

Downy Yellowjacket Vespula flavopilosa

Observer

ceiseman

Date

August 30, 2019 12:32 PM EDT

Description

Feeding on a carcass of what I'm told is probably Paonias excaecata.

Downy Yellowjacket - Photo (c) Don Magnusson, all rights reserved
mokennon's ID: Downy Yellowjacket (Vespula flavopilosa)
Added on January 13, 2020.
Supporting

Photos / Sounds

What

Broad-headed Sharpshooter Oncometopia orbona

Observer

wildcarrot

Date

January 11, 2020 04:31 PM CST
Broad-headed Sharpshooter - Photo (c) Katja Schulz, some rights reserved (CC BY)
mokennon's ID: Broad-headed Sharpshooter (Oncometopia orbona)
Added on January 13, 2020.
Supporting

Photos / Sounds

What

Green Long-jawed Spider Tetragnatha viridis

Observer

bennet

Date

September 17, 2016 11:18 AM EDT
Green Long-jawed Spider - Photo (c) Eric Knopf, some rights reserved (CC BY-NC)
mokennon's ID: Green Long-jawed Spider (Tetragnatha viridis)
Added on December 30, 2019.
Supporting

Photos / Sounds

Square

What

Green Long-jawed Spider Tetragnatha viridis

Observer

paullewis

Date

October 15, 2019 04:15 PM EDT
Green Long-jawed Spider - Photo (c) Eric Knopf, some rights reserved (CC BY-NC)
mokennon's ID: Green Long-jawed Spider (Tetragnatha viridis)
Added on December 30, 2019.
Supporting

Photos / Sounds

What

Green Long-jawed Spider Tetragnatha viridis

Observer

glmory

Date

May 7, 2017 03:55 PM PDT
Green Long-jawed Spider - Photo (c) Eric Knopf, some rights reserved (CC BY-NC)
mokennon's ID: Green Long-jawed Spider (Tetragnatha viridis)
Added on December 30, 2019.
Supporting

Photos / Sounds

What

Green Long-jawed Spider Tetragnatha viridis

Observer

pennyflip

Date

November 29, 2016 09:42 AM HST
Green Long-jawed Spider - Photo (c) Eric Knopf, some rights reserved (CC BY-NC)
mokennon's ID: Green Long-jawed Spider (Tetragnatha viridis)
Added on December 30, 2019.
Supporting

Photos / Sounds

Square

What

Green Long-jawed Spider Tetragnatha viridis

Observer

skitterbug

Date

March 20, 2017
Green Long-jawed Spider - Photo (c) Eric Knopf, some rights reserved (CC BY-NC)
mokennon's ID: Green Long-jawed Spider (Tetragnatha viridis)
Added on December 30, 2019.
Supporting

Photos / Sounds

What

Green Long-jawed Spider Tetragnatha viridis

Observer

ferox_formicae

Date

November 28, 2019 06:35 PM EST
Green Long-jawed Spider - Photo (c) Eric Knopf, some rights reserved (CC BY-NC)
mokennon's ID: Green Long-jawed Spider (Tetragnatha viridis)
Added on December 30, 2019.
Supporting

Photos / Sounds

What

Green Long-jawed Spider Tetragnatha viridis

Observer

kkeivit

Date

July 20, 2018 04:04 PM EDT

Description

Not sure if ID.

Green Long-jawed Spider - Photo (c) Eric Knopf, some rights reserved (CC BY-NC)
mokennon's ID: Green Long-jawed Spider (Tetragnatha viridis)
Added on December 30, 2019.
Supporting

Photos / Sounds

What

Green Long-jawed Spider Tetragnatha viridis

Observer

zoology123

Date

November 4, 2018 07:27 PM EST
Green Long-jawed Spider - Photo (c) Eric Knopf, some rights reserved (CC BY-NC)
mokennon's ID: Green Long-jawed Spider (Tetragnatha viridis)
Added on December 30, 2019.
Supporting

Photos / Sounds

What

Green Long-jawed Spider Tetragnatha viridis

Observer

srickey

Date

April 4, 2019 01:37 PM EDT
Green Long-jawed Spider - Photo (c) Eric Knopf, some rights reserved (CC BY-NC)
mokennon's ID: Green Long-jawed Spider (Tetragnatha viridis)
Added on December 30, 2019.
Supporting

Photos / Sounds

Square

What

Green Long-jawed Spider Tetragnatha viridis

Observer

maxcavitch

Date

August 31, 2019 01:21 PM EDT
Green Long-jawed Spider - Photo (c) Eric Knopf, some rights reserved (CC BY-NC)
mokennon's ID: Green Long-jawed Spider (Tetragnatha viridis)
Added on December 30, 2019.
Supporting

Photos / Sounds

What

Globular Springtails Order Symphypleona

Observer

wildcarrot

Date

December 29, 2019 10:33 AM EST
Globular Springtails - Photo (c) F. Marquard, some rights reserved (CC BY-NC-SA)
mokennon's ID: Globular Springtails (Order Symphypleona)
Added on December 29, 2019.
Supporting

Photos / Sounds

Date

July 6, 2016 09:49 PM EDT
Metylophorus novaescotiae - Photo (c) Bill Keim, all rights reserved
mokennon's ID: Metylophorus novaescotiae, a member of Common Barklice (Family Psocidae)
Added on December 23, 2019.
Supporting

Photos / Sounds

Square

What

F-Winged Barklouse Graphopsocus cruciatus

Observer

janet31

Date

October 31, 2018 03:45 PM EDT
F-Winged Barklouse - Photo (c) Alice Abela, all rights reserved
mokennon's ID: F-Winged Barklouse (Graphopsocus cruciatus)
Added on December 23, 2019.
Supporting

Photos / Sounds

Observer

mobbini

Date

November 24, 2019 03:04 PM CET
Issus - Photo (c) Roland Gromes, some rights reserved (CC BY-SA)
mokennon's ID: Genus Issus, a member of Issid Planthoppers (Family Issidae)
Added on December 21, 2019.
Supporting

Photos / Sounds

Square

Observer

kimberlietx

Date

May 24, 2019 01:52 PM CDT

Description

On Callery Pear

Diplocarpon - Photo (c) Scot Nelson, some rights reserved (CC BY-NC-SA)
mokennon's ID: Genus Diplocarpon, a member of Sac Fungi (Phylum Ascomycota)
Added on December 18, 2019.
Supporting
Added as part of a taxon swap

Photos / Sounds

Square

Observer

xpda

Date

July 11, 2012 05:20 AM UTC
Erasmoneura vulnerata - Photo (c) Marcello Consolo, all rights reserved
mokennon's ID: Erasmoneura vulnerata, a member of Typical Leafhoppers (Family Cicadellidae)
Added on December 14, 2019.
Supporting

Photos / Sounds

Observer

treichard

Date

August 10, 2018 09:55 PM EDT
Prescottia lobata - Photo (c) Martha O'Kennon, some rights reserved (CC BY-NC)
mokennon's ID: Prescottia lobata, a member of Typical Leafhoppers (Family Cicadellidae)
Added on December 13, 2019.
Supporting

Photos / Sounds

Square

Observer

ehjalmarson

Date

September 18, 2019 10:34 PM CDT
Prescottia lobata - Photo (c) Martha O'Kennon, some rights reserved (CC BY-NC)
mokennon's ID: Prescottia lobata, a member of Typical Leafhoppers (Family Cicadellidae)
Added on December 13, 2019.
Supporting
Prescottia lobata - Photo (c) Martha O'Kennon, some rights reserved (CC BY-NC)
mokennon's ID: Prescottia lobata, a member of Typical Leafhoppers (Family Cicadellidae)
Added on December 13, 2019.
Supporting

Photos / Sounds

Square

Observer

allenwoodliffe

Date

September 14, 2019 08:59 PM EDT
Prescottia lobata - Photo (c) Martha O'Kennon, some rights reserved (CC BY-NC)
mokennon's ID: Prescottia lobata, a member of Typical Leafhoppers (Family Cicadellidae)
Added on December 13, 2019.
Supporting

Photos / Sounds

Square

Observer

suegregoire

Date

October 8, 2018 09:26 PM EDT

Description

Scaphoideus Leafhopper 8 Oct 2018

Prescottia lobata - Photo (c) Martha O'Kennon, some rights reserved (CC BY-NC)
mokennon's ID: Prescottia lobata, a member of Typical Leafhoppers (Family Cicadellidae)
Added on December 13, 2019.
Improving

Photos / Sounds

Square

Observer

suegregoire

Date

October 1, 2019 09:06 PM EDT

Description

Scaphoideus Leafhopper hundreds of these at the moth lights 1 Oct 2019

Prescottia lobata - Photo (c) Martha O'Kennon, some rights reserved (CC BY-NC)
mokennon's ID: Prescottia lobata, a member of Typical Leafhoppers (Family Cicadellidae)
Added on December 13, 2019.
Improving

Photos / Sounds

Square

Date

August 15, 2019 10:48 PM EDT
Prescottia lobata - Photo (c) Martha O'Kennon, some rights reserved (CC BY-NC)
mokennon's ID: Prescottia lobata, a member of Typical Leafhoppers (Family Cicadellidae)
Added on December 13, 2019.
Leading

Photos / Sounds

Observer

tomegatherion

Date

September 14, 2019 12:31 PM MSK
Longitarsus - Photo (c) Jason Michael Crockwell, some rights reserved (CC BY-NC-ND)
mokennon's ID: Genus Longitarsus, a member of Flea Beetles (Tribe Alticini)
Added on December 11, 2019.
Supporting

Photos / Sounds

Square

Observer

kimberlietx

Date

April 29, 2017 01:02 AM CDT

Description

I'm just uploading these photos and not trying to ID yet, or look for duplicates. I'm determined to get all of these Costa Rica pics uploaded before the end of the year!

Atteva pustulella - Photo (c) Gustavo Masuzzo, all rights reserved
mokennon's ID: Atteva pustulella, a member of Tropical Ermine Moths (Family Attevidae)
Added on December 11, 2019.
Supporting

Photos / Sounds

Square

Observer

claggy

Date

December 5, 2019 02:38 PM CST

Place

Texas, US (Google, OSM)

Description

First Leucauge I've seen in Texas so far! This was the only one I came across.

1-1.5mm

Leucauge - Photo no rights reserved
mokennon's ID: Genus Leucauge, a member of Long-jawed Orbweavers (Family Tetragnathidae)
Added on December 10, 2019.
Supporting

Stats

  • 191