04 Patella ulyssiponensis. Length 17 mm. North Yorkshire. September 2014.

In profile, anterior and posterior straight.

 

Key id. features BELOW

SPECIES DESCRIPTION part A 2Pu flic.kr/p/BG8mKq

SPECIES DESCRIPTION part B 3Pu flic.kr/p/BRHsiR

OTHER SPECIES ALBUMS

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Key identification features of typical British specimens.

 

Patella ulyssiponensis

1) Basal half of pallial tentacles has opaque pigment which can be white, off-white, cream or, on large specimens, yellowish or orange. The distal half fades to a translucent tip. Opaque basal half is often distinct from translucent mantle-skirt that they arise from, so it is possible to confuse with P. depressa. It is important to use pallial tentacles in combination with foot-colour/shell-length for identification. Examples at 26Pu flic.kr/p/BGqszN .

2) Foot is NOT pitch-brown/black or dark khaki. It can be whitish when young 30Pu flic.kr/p/BGqk4q becoming yellowish 31Pu flic.kr/p/BGrKw1 and, sometimes, orange with age 21Pu flic.kr/p/AUuNww . Juveniles under 12mm length may show a blackish internal shadow through the thin pale translucent foot 30Pu flic.kr/p/BGqk4q as they lack gonads above the foot that mask the dark viscera of adults.

 

 

Similar species

 

Patella vulgata

Extremely variable species; foot colours and nearly all shell-features have overlaps with P. depressa and P. ulyssiponensis.

1. Pigment-less pallial tentacles are slender, translucent and same colour as mantle-skirt they arise from. 40Pu flic.kr/p/BPJ1vQ .

Cautions:

Pallial tentacles of P. vulgata may look white when arise from colourless mantle-skirt in some lighting, but no pigment 41Pu flic.kr/p/AUxuXs .

Translucency and fineness of pallial tentacles of P. vulgata often make discernment difficult, especially when mantle skirt retracted from shell-rim and pallial tentacles viewed against shell 42Pu flic.kr/p/BGtg3y ; often virtually invisible when out of water as may be retracted as well as highly translucent 43Pu flic.kr/p/AUDqUz .

Foot colour of P. vulgata varies greatly, sometimes orange resembling P. ulyssiponensis 53PualbumPvhigh.

Shell interior can be white or tinted orange in P. vulgata 53PualbumPvhigh and 44Pu flic.kr/p/BPKJ6G .

 

Patella depressa

[1 & 2 in combination, not singly, are diagnostic of typical specimens but exclude intermediates.]

1. Pigmented pallial tentacles are opaque chalky-white for more than half of extended-length; may have translucent tip; distinctly whiter than buff mantle-skirt from which they arise 45Pu flic.kr/p/BJLMBx . Even when mantle-skirt retracted, pallial tentacles often clearly visible contrasting with the darker mantle 46Pu flic.kr/p/AUxm6u .

2. Sole of foot pitch-brown 47Pu flic.kr/p/AUDiJH to black 46Pu flic.kr/p/AUxm6u .

3. On shell-interior, whitish projecting points of ribs have short, unglazed, chalky, pure-white central line, but reduced or lacking where projecting points of ribs eroded 48Pu flic.kr/p/BS4e7v . [This feature recently recognised by S. Payne, and applies to all in large sample examined by IFS. Unsure yet if universal on P. depressa and exclusive of P. vulgata and P. ulyssiponensis.]

Caution:

Shell interior can be orange-cream in P. depressa 49Pu flic.kr/p/BixiVz

 

Patella caerulea Linnaeus, 1758.

Does not occur in Britain. In Iberia and Mediterranean, separation from it of some specimens of P. ulyssiponensis could not be achieved with foot colour and shell morphology by Sanna et al. (2011) who relied on the use of DNA sequencing. They did not mention attempting the use of pallial tentacle colour on live specimens; it may be worth investigation. See Sanna et al. for images of P. caerulea.

 

Done