02 Patella ulyssiponensis. Length 18.7 mm. North Yorkshire. September 2014.

Lowest profile (H/L 18%) in sample of eighteen.

It is often asserted that interior shell-layers conceal the outer shell so that, internally, “marginal rays are never conspicuous” (Fretter and Graham, 1994), but this does not apply to many shells below 40 mm length, such as this one from a shore in North Yorkshire where the majority have thin inner layers revealing exterior colour rays.

 

SPECIES DESCRIPTION part A BELOW

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

Key id. features 4Pu flic.kr/p/BG8hhs

OTHER SPECIES ALBUMS www.flickr.com/photos/56388191@N08/collections/

PDF available at www.researchgate.net/profile/Ian_Smith19/research

 

Terms in text used with restricted or specialised meaning are marked with hashtag#; refer to GLOSSARY below.

 

Patella_ulyssiponensis Gmelin, 1791.

 

Current taxonomy: World Register of Marine Species (WoRMS)

www.marinespecies.org/aphia.php?p=taxdetails&id=140684

Synonyms: Patella aspera Lamarck,1819 (widely used by many authors until 1970s but now considered by WoRMS to be separate Macaronesian species P. aspera Röding, 1798); Patella_athletica Bean, 1844; P. depressa auct.

 

Jeffreys (1865) mistakenly took the rudimentary description of P. depressa by Pennant (1777) to be what is currently (2015) called P. ulyssiponensis. Until 1923, most authors followed Jeffreys in applying the name P. depressa Pennant to the wrong species, and in using the name P. intermedia Jeffreys for what is now recognised as P. depressa Pennant. Examination of Pennant's type specimen by Tomlin (1923) exposed the error and authors started to use the name P. athletica Bean, 1844, for what is now called P.ulyssiponensis but, probably to avoid confusion, many retained use of P. intermedia Jeffreys for the true P. depressa Pennant, despite Pennant's priority, until the 1970s (e.g.Yonge & Thompson, 1976).

Vernacular names: China limpet (English); Brenigen dorfelen (Welsh); Ruwe schaalhoren (Dutch);

 

Meaning of name: Patella (Latin) = little pan, ulyssiponensis (Latin) = from Lisbon.

 

Shell Description

Patellid limpets have great geographical variation within and between species; this account refers to British specimens.

Up to 50mm long and 20mm high 1Pu flic.kr/p/BpzHx5 . Strong. Conoid; apex to anterior of centre, base ovoid, widest and sometimes angulated at posterior. Profile usually low (H/L 18-34%, sample of 18) 2Pu flic.kr/p/BG8mKq & 3Pu flic.kr/p/BRHsiR . In profile, anterior and posterior straight 4Pu flic.kr/p/BG8hhs , varying to slightly convex 3Pu flic.kr/p/BRHsiR or slightly concave 5Pu flic.kr/p/AUccwq . When not eroded, often sculpture of single, narrow, pale radiating ribs with varying numbers of intervening weaker ribs 6Pu flic.kr/p/AUicEZ but often obscured by algal growths 7Pu flic.kr/p/AUibCP & 8Pu flic.kr/p/BpznqS . Sometimes ribs project from aperture-rim as points 9Pu flic.kr/p/Bicbta & 10Pu flic.kr/p/BRH5pv , but frequently eroded down 11Pu flic.kr/p/BPsC4f . Dark radiating rays between strong ribs often coalesce into bands 11Pu flic.kr/p/BPsC4f .

Most published descriptions and illustrations are confined to specimens with well-developed, thick, porcellaneous layers on the shell-interior e.g. www.conchsoc.net/spAccount/patella-ulyssiponensis . Some of this form show features defined by differences of orange staining 14 Pu flic.kr/p/BpCkES and/or reflectivity Pu1 flic.kr/p/BpzHx5 resulting from differences in crystal-form of shell-material made by different parts of mantle. Following regions may then be recognised: 1) aperture rim, minute part (or none) of pigmented exterior shell-layer; secreted by mantle-edge, 2) wide peripheral “skirt layer” that reflects light, often iridescing blue, from many short crystalline lines parallel to rim; secreted by mantle-skirt, 3) narrower, matt, opaque, “pallial groove-band”; secreted by mantle roofing groove that contains gills, 4) translucent, horseshoe-shape “pedal-retractor muscle scar”; mark left by muscle attachment, 5) very thin “anterior mantle-attachment scar” connecting ends of pedal-retractor scar; mark left by mantle attachment, 6) central “amphora area” enclosed by scars 4 & 5; secreted by mantle over visceral hump, 7) short mark across pallial groove-band where efferent pallial vessel enters nuchal cavity through gap in pallial gills. On this form, interior layers conceal outer shell so, internally, “marginal rays are never conspicuous” (Fretter and Graham, 1994).

However, on some shores , e.g. in north Yorkshire, majority have thin inner layers revealing exterior colour rays 2Pu flic.kr/p/BG8mKq & 11Pu flic.kr/p/BPsC4f , sometimes across whole shell 16Pu flic.kr/p/BpChy1 (apart from some with length c.40mm and over 12Pu flic.kr/p/AUfeNo ) . On these, the structural features 1-7 described above are usually indiscernible or ill-defined, apart from frequently orange-stained amphora area 13Pu flic.kr/p/BRLd2Z and iridescent lines in skirt-layer 15Pu flic.kr/p/AUm6kt .

Spat, length 1mm, lack ridges on main anteroposterior axis and have broad, prominent, mid-lateral pigment lines running straight (not swept forwards or backwards) from apex to lip.

 

Body description

Translucent white head, with pink internal odontophore showing through 17Pu flic.kr/p/BJtvfi ; has substantial snout , folds in at posterior, with large mouth (transverse when shut) fringed by thick, yellow, outer lips (whitish when small); inner lips darker yellow, open laterally for protrusion of radula 18Pu flic.kr/p/Bif5cB . Cephalic tentacles similar colour to head and/or mantle-skirt 19Pu flic.kr/p/AUeYf9 & 18Pu flic.kr/p/Bif5cB , with small black eye in slight swelling at base. Eye is primitive (or degenerate) cavity, open to seawater and lined with black retina cells 17Pu flic.kr/p/BJtvfi & 18Pu flic.kr/p/Bif5cB . Mantle skirt translucent, usually darker than body colour; buff-white/cream 5Pu flic.kr/p/AUccwq , buff-grey 20Pu flic.kr/p/AUeX8j , or yellow 21Pu flic.kr/p/AUuNww ; colour most saturated when skirt retracted from shell-periphery 22Pu flic.kr/p/BGqz3N . Skirt contains efferent pallial vessel 23Pu flic.kr/p/BGqwhs . Mantle cavity consists of nuchal cavity over head, and pallial groove filled with pallial gills around entire periphery of foot-head 24Pu flic.kr/p/BS1DhR ; no ctenidium. Each gill is tongue-shaped leaflet attached by stalk to distal wall of pallial-groove and has densely ciliated groove on stalk and thickened rim 25Pu flic.kr/p/BGqt5A (Fretter & Graham, 1994). Mantle-edge has many white, off-white , cream or, on large specimens, yellow or orange pallial tentacles 26Pu flic.kr/p/BGqszN ; basal half opaque becoming translucent and less intensely coloured distally; opaque basal parts distinct from translucent mantle-skirt that they arise from. Length of pallial tentacles alternates around perimeter with two or three short ones between each pair of long ones; length varies with extension 27Pu flic.kr/p/AUuCc3 & 28Pu flic.kr/p/BPGWSQ . Visibility of pallial tentacles, and their position relative to shell, vary with degree of extension of mantle skirt 10Pu flic.kr/p/BRH5pv . Pedal-retractor muscle, a U of white muscle bundles 28Pu flic.kr/p/BPGWSQ demarcated by gaps 24Pu flic.kr/p/BS1DhR , attaches body/foot to shell 22Pu flic.kr/p/BGqz3N . Sole of foot approximately circular with flattened anterior 29Pu flic.kr/p/AUAAHD to broadly elliptical 5Pu flic.kr/p/AUccwq . Colour of sole varies: small whitish ones may have shadow of dark viscera if gonads undeveloped 30Pu flic.kr/p/BGqk4q ; adults, pale-yellow/cream, yellow 31Pu flic.kr/p/BGrKw1 or orange 21Pu flic.kr/p/AUuNww ; sometimes slightly-greenish tinted median zone where foot thinnest if greenish female gonads resting on inner surface of foot. White or yellowish-white 32Pu flic.kr/p/BpU3pC sides of foot lack features such as epipodial tentacles. When crawling, usually only extended pallial tentacles and, perhaps, tips of cephalic tentacles protrude beyond shelter of shell. No penis as fertilization external.

 

Further detail visible with simple dissection

Shell removal by severing pedal-retractor muscle shows muscle-bundles clearly 28Pu flic.kr/p/BPGWSQ ; anterior bundle on each side is largest and strongest as must firmly pull down shell further to anterior where bundles are absent. Shell removal exposes entire mantle 33Pu flic.kr/p/BJKhmk subdivided into a) pale translucent mantle-skirt, b) narrow black band over pallial-groove containing gills, c) large black amphora-shaped area, sometimes paler near vertex, over viscera and nuchal cavity containing the head 34Pu flic.kr/p/BGrCQW and d) pale anterior mantle-attachment. Removal of black amphora area of mantle reveals viscera 35Pu flic.kr/p/BivTv4 including heart, digestive gland, intestine and, if in breeding condition, gonads protruding from below. When roof of nuchal cavity removed, translucent white head, usually showing pink of internal odontophore, is visible 35Pu flic.kr/p/BivTv4 , and removal of viscera reveals radula, folded to fit in body 36Pu flic.kr/p/AUvMhW . Removal of head's epithelium reveals odontophore and anterior of radula 37Pu flic.kr/p/BGrzwG . Radula long, relative to shell length, ( R/S 80-140%); shorter on average (but with overlapping range) than those of P. vulgata (113-230%) and P. depressa (140-270%) (Fretter & Graham, 1962, p.172). Fully mineralized, rust-coloured radular teeth, ready for action, clearly visible on hyaline shield at anterior; those further back partly obscured as in white radular sac. At anterior of radula, a white chitinous unarticulated jaw#, and white, cuticularized, triangular licker divided into plate-like ridges by deep transverse grooves 38Pu flic.kr/p/BJKboP . Each row of teeth arranged in docoglossan formula, 3+D+2+R+2+D+3: at centre, two pairs of large, unicuspid, pigmented lateral teeth (with small, unpigmented rachidian/median tooth hidden from easy view at their base), and near each margin of ribbon a single, tricuspid, pigmented, dominant-marginal tooth with, close-by, three inconspicuous, unicuspid, marginal teeth. Before and during summer breeding season, large gonads occur in mature adults between viscera and foot; female ovaries granular and yellow to green; male testes pink/orange with numerous interconnected tubules 39Pu flic.kr/p/BGrxio .When fully developed, gonads spread up around periphery of visceral mass 35Pu flic.kr/p/BivTv4 .

 

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

 

GLOSSARY

 

amphora – (on interior of limpet shell) Roman amphora-shaped area enclosed by scars of pedal-retractor muscle and anterior mantle-attachment.

 

anteroposterior – (of linear feature) aligned from anterior to posterior.

aperture – mouth of gastropod shell; outlet for head and foot.

apex - earliest formed part of a gastropod shell, the summit of the cone. (In this limpet-account restricted to the exterior of the shell, and “vertex” used for the interior.)

 

auct. - (abbreviation of “auctorum” = “of authors”) name, often of another valid species, used in error for this one by other author(s). en.wikipedia.org/wiki/Auctorum

 

cephalic – (adj.) of or on the head.

 

cilia – (pl.) microscopic linear extensions of membrane that move in rhythmic waves to create locomotion, or move particles and liquids e.g. inhalent water currents. (“cilium” singular). (Electron scanning microscope image at flic.kr/p/qQB5zj )

 

ciliary – (adj.) relating to or involving cilia.

coll. – in the collection of (named person or institution) (compare with legit).

conoid – shaped like a cone.

ctenidium – comb-like molluscan gill; usually an axis with a row of filaments either side.

 

ELWS – extreme low water spring tide (usually near March and September equinoxes).

 

epipodial - (adj.) of the epipodium (collar or circlet running round sides of foot of some gastropods).

 

epithelium – membranous covering of internal and external surfaces of animal's body, e.g. skin and lining of tubes and cavities.

 

head scar – term used by many British authors for patch of different shell-material, and often different colour, near vertex of interior of limpet shell; misnomer as the mobile head, free of any attachment to the shell or mantle-roof of the nuchal cavity cannot make a scar. A preferable term is “vertex patch”.

 

height – (of limpet) perpendicular distance from apex to plane of aperture-rim (best measured with callipers).

 

hyaline shield – transparent sheet of chitin at anterior of radula that rests on bolsters of odontophore; attachment point for retractor muscles of radula; helps guide food particles into mouth.

 

jaw - unarticulated chitinous structure that encloses inner lips of Patella spp. at sides and anterior.

legit – (abbreviation; leg.) collected/ found by (compare with coll.)

licker - cuticularized structure with plate-like ridges and deep transverse grooves at tip of radula of Patella spp.; retains and sweeps up food particles.

 

Macaronesia – Madeira, Canary Islands, Cape Verde Islands and Azores.

 

mantle – sheet of tissue covering visceral mass of molluscs. Secretes shell of shelled species, and forms part or all of dorsal body surface (notum) of those without shells. (See mantle skirt.)

 

mantle skirt – extension on gastropods of mantle proper as a flap roofing a cavity containing gills, genital and renal openings, anus etc. On limpets, skirt and cavity extend around periphery of animal.

 

MLWS - mean low water spring tide level (mean level reached by lowest low tides for a few days every fortnight; Laminaria or Coralline zone on rocky coasts).

nuchal – (adj.) of nape of the neck.

nuchal cavity – cavity roofed by mantle skirt that contains head of limpet; part of mantle cavity (remainder consists of pallial groove on each side of body).

 

ovoid – egg-shaped, (as a solid or in outline).

ovate – egg-shaped, (as a solid or in outline).

 

pallial groove band – shell material deposited on interior of shell by strip of black mantle roofing the pallial groove that contains the gills. On British Patella spp. it is often clouded-white.

 

pedal retractor muscle – strong muscle that retracts foot into shell of most gastropods, but on limpets is used to clamp shell to substrate, a.k.a. “foot muscle”.

 

porcellaneous – resembling vitreous glazed ceramic material.

 

retrograde - (of locomotion waves on foot) waves travel from anterior to posterior.

scar – mark on shell made by attachment point of muscle or other body part.

 

skirt shell layer - shell material deposited on interior of shell by mantle skirt. On British Patella spp. colourless when deposited, and clouded white, or transparent showing the colours of the outer layer. Crystalline structure causes short lines of blue iridescence parallel to the aperture rim on all four British species of Patella when the light is right.

 

tricuspid - (of tooth) having three points.

trochophore – spherical or pear-shaped larva that swims with aid of girdle of cilia. Stage preceding veliger, passed within gastropod egg in most spp. but free in plankton for patellid limpets, most Trochidae and Tricolia pullus.

 

unicuspid - (of tooth) having a single point.

veliger – shelled larva of marine gastropod or bivalve mollusc which swims by beating cilia of a velum (bilobed flap).

 

vertex – angle at highest point on interior of limpet-shell. [Synonym of “apex”, chosen (by IFS) to help avoid confusion with the highest point, apex, on the exterior. In classical Latin “vertex” was used for the “pole of the heavens”, obviously only seen from below.]

 

vertex patch –layer of different shell-material, and often different colour, at vertex of interior of limpet shell. (See “head scar”.)

 

Done