Left: Yellow form of Acanthodoris pilosa. Durham coast, 2014. © P. Lightfoot.
Right: Soft, tall, thin, conical tubercles on mantle. Menai Strait, North Wales. March 2015.
FULL 9 POINT COMPARISON with J. tomentosa:
Acanthodoris pilosa (Abildgaard in Müller, 1789)
1: Usual maximum length 40 mm.
2: Dorsally white or brown 30 Jorunna tomentosa album, comparison images of Acanthodoris pilosa. , occasionally, black or yellow 31 Jorunna tomentosa album, comparison image of Acanthodoris pilosa. . Pale colours may be evenly freckled darker, but not with large patches of pigment.
3: Soft, tall, thin, conical tubercles on mantle 31 Jorunna tomentosa album, comparison image of Acanthodoris pilosa., but sometimes contracted or poorly developed and not so distinctive 32 Jorunna tomentosa album, comparison images of Acanthodoris pilosa.. Body soft and yielding.
4: Voluminous tripinnate gills can contract but not retract into pocket; usually, opaque white along each side of translucent midribs forms a star when gills expanded 32 Jorunna tomentosa album, comparison images of Acanthodoris pilosa. . Anal papilla not brown, except possibly on brown specimens.
5: Base of gills not surrounded by collar-like sheath.
6: Narrow oral veil extended laterally into broad, flat oral tentacles. Anterior of veil has two protrusions centrally 33 Jorunna tomentosa album, comparison image of Acanthodoris pilosa. .
7 Convex body with raised profile 30 Jorunna tomentosa album, comparison images of Acanthodoris pilosa. .
8: Long rhinophores bent rearwards; concolorous with body and no dark dots on pale colour forms. Up to 24 lamellae on large specimens.
9: Posterior of foot protrudes a little when in motion.
Jorunna tomentosa
1: Length up to 30 mm (Neuhaus et al, 2021), 55 mm (Thompson and Brown, 1984), often a similar size to Doris pseudoargus.
2: Dorsally, sandy-brown 01 Jorunna tomentosa. Length 60 mm. Intertidal. Orkney. April 1975. , reddish brown, grey-white, grey-cream, yellow 02 Jorunna tomentosa. , yellow cream 03 Jorunna tomentosa. Length 55mm. Menai Strait, Wales. June 2013. , buff-orange, or white 04 Jorunna tomentosa. West Anglesey, Wales. March 2014.. Small opaque white glandular structures near periphery of mantle 03 Jorunna tomentosa. Length 55mm. Menai Strait, Wales. June 2013. but sometimes not discernible 01 Jorunna tomentosa. Length 60 mm. Intertidal. Orkney. April 1975. . Usually, scattered small dark spots and a few dark blotches in a longitudinal row on each side 05 Jorunna tomentosa. Split, Croatia. November 2012. © J. Prkić . ; sometimes blotches absent, or few and small 11 Jorunna tomentosa. 55mm long. Menai Strait, Wales. June, 2013. and occasionally the small spots are absent.
3: Mantle has crowded, small, match-like, retractile tubercles (caryophyllidia) 08 Jorunna tomentosa. Rhinophores from 34 mm and 55 mm long animals. Menai Strait, Wales. with a ring of sharp projecting spicules surrounding the rounded apex. Body has velvety appearance and soft feel.
4: Large yellow-cream to grey gills around brown anal papilla 02 Jorunna tomentosa. & 04 Jorunna tomentosa. West Anglesey, Wales. March 2014. . Gills are often paler than the mantle and sometimes have dark dots.
5: Base of extended gills surrounded by distinct collar-like sheath 09 Jorunna tomentosa, gills and gill sheath. Lengths of animals 55mm and 43mm. Anglesey, Wales. which closes over the gills when they are retracted into a pit 12 Jorunna tomentosa. Length of animal 43mm. Menai Strait, Wales. February 2014. .
6: Slender tapered oral tentacles 15 Jorunna tomentosa. Animal 55mm long. Menai Strait, Wales. June, 2013. .
7: Convex body with raised profile 07 Jorunna tomentosa. West Anglesey, Wales. March 2014. .
8: Short, stout rhinophores have a translucent whitish, or slightly tinted, basal stem and a conical, lamellated, yellow-cream to grey, distal part bearing red to brown pigment dots/marks 08 Jorunna tomentosa. Rhinophores from 34 mm and 55 mm long animals. Menai Strait, Wales. .
9: Posterior of foot protrudes when in motion 19 Jorunna tomentosa. Length 43mm. Menai Strait, Wales. February 2014. .