I could not figure out how to identify Pagurus hirsutiusculus and Pagurus venturensis, so I scrutinized all 50,000 iNat hermit crab data and found a way to identify them both. Please refer to this page.

Basic characteristics of "Pagurus hirsutiusculus".

1. The second antennae (longer) are brown with white stripes.
2. cornea (eye) is black and white.

3. ocular peduncle (eye axis) thick and short, with black vertical lines.
   The juvenile ocular peduncle is entirely red with a white longitudinal line.

4. shield (back) is dark.
5. a blue spot may appear proximal (knee) to the propodus (tibia) of the walking leg.
6. distal portion (ankle) of propodus (tibia) of walking leg white, vertical line of propodus inconspicuous, entire propodus appears as a black band.
7. The carpus (thigh) of the pedipalps is white as a juvenile, and the black band appears at maturity.
8. prefer small shells that hide only the abdomen.
9. The dactyl (finger) junction of the right cheliped is darkened and bordered prominently.

Basic characteristics of "Pagurus venturensis".

1. The second antennae (longer) are brown with white stripes.
2. cornea (eyes) light pink.

3. ocular peduncle (eye axis) elongate, brown or red.
   Juvenile ocular peduncle may be entirely red with a pale white line.

4. shield (back) is a bright color.
5. distal portion (ankle) of propodus (tibia) of walking leg white with prominent vertical line on black band of propodus.
6. The black bands on the carpus (thighs) of the gait legs are conspicuous even in juvenile stages.
7. prefer shells with a wide horizontal shell opening.
8. The dactyl (finger) junction of the right cheliped is white with an inconspicuous border.

Please point out any errors.

P.S.: Representative photos of Pagurus hirsutiusculus and Pagurus venturensis have been reorganized and replaced with photos that are easier to identify.

Pagurus hirsutiusculus
https://www.inaturalist.org/taxa/63219-Pagurus-hirsutiusculus

Pagurus venturensis
https://www.inaturalist.org/taxa/635130-Pagurus-venturensis

Posted on June 5, 2023 09:39 PM by eijimyorin