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Key identification features
Features 1 to 4, below, accord with Forbes & Hanley (1853) and Gittenberger (2004). The former aggregated M. myosotis with M. denticulata but “scrupulously kept apart their description.” Many currently used identification guides aggregate them and their features under M. myosotis and DNA sequencing by National Museum Wales shows they are indeed the same species. Distribution maps on GBIF and NBN include M. denticulata occurrences under “M. myosotis”..
To observe aperture sculpture the animal must be well withdrawn, and the shell tilted at different angles. Sometimes the outer (palatal) lip sculpture of an earlier growth stage is visible deep into the aperture and should be used if the sculpture on new growth has not yet developed. It is advisable to examine several specimens of different sizes from a site; sometimes both are present.
2. Inner (columellar/parietal) lip has only 2 or 3 apertural protrusions 3Mm flic.kr/p/23Wmsve .
3. Outer (palatal) lip has a single apertural denticle or none 3Mm flic.kr/p/23Wmsve . Some have a pale apertural ridge running close to the lip.
4. Flesh colour of normally extended dorsal body is grey 1Mm flic.kr/p/2drL1Pw . Shade and intensity varies with age, extension and whether in air or water, but not pure white when adult.
5. Habitat: among vegetation, often under driftwood, on low salinity estuarine saltings 38Mm flic.kr/p/2exLH2t and Saltmarsh-grass sward by tidal rivers 39Mm flic.kr/p/2da1TMi a little above and below EHWS. Locally abundant. (May occur with M. denticulata under stones on/near saltings 40Mm flic.kr/p/2exLGc2 .)
Myosotella denticulata DNA sequencing by National Museum Wales has shown this to be the same species as M. myosotis
1. Live shell brown (beachworn shells may be dull whitish). Usual adult height 3.5 mm to 7.5 mm, exceptionally 10 mm 45Mm flic.kr/p/QMuTi8 .
2. Inner (columellar/parietal) lip has 2 to 5 apertural protrusions 45Mm flic.kr/p/QMuTi8 .
3.Outer (palatal) lip has 2 to 7 (or more) apertural protrusions 45Mm flic.kr/p/QMuTi8 , sometimes set into a pale ridge which occasionally submerges them. [If no protrusions, check further back in aperture for protrusions on earlier lip position; may be visible from exterior through translucent shell , with or without connecting streaks.]
4. In its typical non-salting habitat, the flesh colour of normally extended dorsal body is white or very pale whitish grey, with darker grey tentacles 46Mm flic.kr/p/2da1NUc . But when it occurs in muddier conditions, it may be as dark as M. myosotis 47Mm flic.kr/p/QMuSYv .
5. Habitat: typically under slightly embedded stones at Extreme High Water Spring level and above (supralittoral) on sheltered coast without salting vegetation at fully marine salinity. Occasionally under stones on landward edge of Saltmarsh-grass sward by tidal rivers with low salinity 40Mm flic.kr/p/2exLGc2 .
Leucophytia bidentata (Montagu, 1808).
Features 1 to 4 conform with Montagu's original description and image.
1. Live shell slightly-translucent ivory-white; yellow viscera may show through spire 48Mm flic.kr/p/2da1NEe . Usual adult height to 5 mm, occasionally to 7 mm. Sutures shallower and whorls less rounded than on M. myosotis 49Mm flic.kr/p/2da21sH .
2. Inner (columellar/parietal) lip has 2 protrusions within the aperture; not more 49Mm flic.kr/p/2da21sH .
3. Outer (palatal) lip has no protrusions or rib (sometimes in a photo, a strong growth line might be mistaken for a rib 49Mm flic.kr/p/2da21sH ).
4. Flesh colour of normally extended dorsal body is amost pure white 48Mm flic.kr/p/2da1NEe , but when contracted into body-whorl colour saturation gives it a cream appearance.
5. Lives in deep, silty, rock crevices between High Water Neap level and Low Water Spring level. Also under stones embedded into soil-like substrate at Extreme High Water Spring level and a little above on sheltered coast where it is often with M. denticulata.