marinvert.senckenberg.science/image-browse/

Key identification features
Identification should be made using a combination of features as some elements may vary.
Tritia reticulata
1. Maximum height 30mm.
2. Spire variably slender, flat-sided, sharply pointed cone with almost flat whorls on spire and shallow suture 1Tr 01 Tritia reticulata (body whorl convex). Juveniles are more squat, taper more sharply and may have slightly concave-sided spire 2Tr 02 Tritia reticulata.
3. Smooth protoconch, c.1mm diameter, often persists to form a fine, sharp apex 8Tr 08 Tritia reticulata , even when worn10Tr 10 Tritia reticulata .
4. Costae (axial ribs) intersect with spiral ridges to create reticulate arrangement of squarish bosses 7Tr 07 Tritia reticulata . In Britain, number of costae on body whorl is 15 to 23 (pers. obs. IFS, 2019), [15 to 20 (Jeffreys, 1867)], and, in Ria de Vigo, Spain, 16 to 23 (Rolan and Luque, 1994).
5. The final costa is rarely sufficiently thickened to form even a slight labial varix 4Tr 04 Tritia reticulata .
6. Teeth within the outer (palatal) lip unevenly sized, 1 or 2 near middle often most prominent 12Tr 12 Tritia reticulata. Shell height 27.6mm. Oval aperture pointed adapically. Dorset, England. April 2012. . “inner lip – – is more or less tuberculated” (Jeffreys, 1867) (teeth/small ribs may be absent, especially on young ones).
7. When live and unworn, brown periostracum covers shell except protoconch and white rim of outer (palatal) lip 5Tr 05 Tritia reticulata . When periostracum removed, shell exterior is matt whitish/buff 7Tr 07 Tritia reticulata , unless stained by epizooic growth or other matter16Tr 16 Tritia reticulata. Matt exterior and glossy interior of shell stained greenish by epizooic alga. Llŷn Peninsula, N. Wales. March 2016. . Interior is glossy white 3Tr 03 Tritia reticulata .
8. Semicircular, glossy, opaque, white parietal lip covers large part of body whorl 12Tr 12 Tritia reticulata. Shell height 27.6mm. Oval aperture pointed adapically. Dorset, England. April 2012. ; may be stained by epizooic growth or other matter16Tr 16 Tritia reticulata. Matt exterior and glossy interior of shell stained greenish by epizooic alga. Llŷn Peninsula, N. Wales. March 2016. .
9. White columella and siphonal canal. No dark spot within canal 3Tr 03 Tritia reticulata .
10. Siphonal canal meets palatal lip at slightly-acute or right angle when viewed end-on13Tr 13 Tritia reticulata. Opening of siphonal canal. Shell heights 21.8mm & 24.7mm. West Anglesey, Wales. March 2014. . [Beachworn specimens may have angle worn to obtuse and resemble T. nitida 37Tr 37 Tritia reticulata. Beachworn shell 22.1mm high. Llŷn, North Wales. August, 1968. .]
11. 4 to 5 grooves on columellar neck of siphonal canal 7Tr 07 Tritia reticulata [Often worn away, so use 4 or 5 to confirm T. reticulata; but those with 3, fewer or none may be either T. nitida or worn T. reticulata11Tr 11 Tritia reticulata & 38Tr 38 Tritia reticulata album. Height 27.2mm. Beached shell. Blackwater Estuary, Essex, England. September 2019. Leg. S. Taylor. .]
12. Body flesh light sienna (yellowish) 11Tr 11 Tritia reticulata (juveniles, whitish20Tr 20 Tritia reticulata. Juvenile. Shell height 5.6mm. West Anglesey, Wales. May 2016. ), heavily marked with small blotches of white and brown/black. Uncertain whether grey body only on T. nitida.
13. Egg capsules like a flat, circular brandy bottle that broadens with age 39Tr 39 Tritia reticulata album. Egg capsules. Left: T. reticulata, Anglesey, Wales, May 2016. Right: T. nitida, Oosterschelde, Netherlands, August 2019, © B. van der Sanden. . Mean height 4.07mm, width 3.25mm (Rolan & Luque, 1994).
14. Sandy sediment sublittorally, and LWS on rocky shores with areas of sand, all round Britain and Ireland.

Similar species
Tritia nitida (Jeffreys, 1867)
WoRMS accepts T. nitida as a valid species; supported by chromotology (Collyer, 1961), comparative morphology (Rolan & Luque, 1994), allozymes (Sanjuan et al., 1997) and DNA (Couceiro et al., 2012) ,further detail at flic.kr/s/aHsmHvjqNk . Populations vary geographically, so some features may not match those below, which are marked (J) for Thames, Orwell and Roach estuaries in S.E. England in Jeffreys (1867); (B) for sample of 220 in 2019 from Blackwater estuary in S.E. England; (S) for Ria de Vigo, N.W. Spain in Sanjuan et al. (1997); (R) for Ria de Vigo in Rolan and Luque (1994) and (P) for northern Adriatic Italy and Croatia (J. Prkić, 2019, pers.comm. September 2019). So use a combination of features when making an identification.
1. Maximum height 25mm (J), exceptionally (2% of strandline sample) 26 to 30mm (B) 46Tr 46 Tritia reticulata album. COMPARISON of (on left) Tritia nitida, height 26.3mm, with T. reticulata, height 27.2mm. Beached shells collected together from Blackwater Estuary, Essex, England in September 2019 by S. Taylor. , 30mm in Galicia, Spain (Trigo et al., 2018), 40mm in Italian Adriatic (P) 47Tr 47 Tritia reticulata album. COMPARISON image of large T. nitida from Italian Adriatic. © J. Prkić. .
2. Adult T. nitida spire-whorls convex in Essex 46Tr 46 Tritia reticulata album. COMPARISON of (on left) Tritia nitida, height 26.3mm, with T. reticulata, height 27.2mm. Beached shells collected together from Blackwater Estuary, Essex, England in September 2019 by S. Taylor. & 48Tr 48 Tritia reticulata album. COMPARISON images of T. nitida. Shell heights: 12.9mm, 19.4mm, 21.6mm, 26.3mm. Beached shells. Blackwater Estuary, Essex, England. September 2019. Leg. S. Taylor. but may be less tumid in other parts of Britain and Ireland 49Tr 49 Tritia reticulata album. COMPARISON image of (probable) T. nitida feeding on carrion. Aughrus, Connemara, Ireland. June, 2017. © M. Thomas. . Jeffreys (1867), stated “whorls flattened; – – suture deeper [than on T. reticulata]”. Compared to gastropods generally, the gentle convexity of the whorls on Essex T. nitida could be said to be flattish, but they are more convex than on T. reticulata, resulting in the deeper suture Jeffreys mentions. In the Adriatic, T. nitida whorls vary from convex to nearly flat 50Tr 50 Tritia reticulata album. COMPARISON image of T. nitida. Croatia, Adriatic. © J. Prkić. .
3. Smooth protoconch is frequently worn/broken off to give a blunt apex 48Tr 48 Tritia reticulata album. COMPARISON images of T. nitida. Shell heights: 12.9mm, 19.4mm, 21.6mm, 26.3mm. Beached shells. Blackwater Estuary, Essex, England. September 2019. Leg. S. Taylor. (appears to persist more on Mediterranean T. nitida 50Tr 50 Tritia reticulata album. COMPARISON image of T. nitida. Croatia, Adriatic. © J. Prkić. ).
4. In Britain, number of costae on body whorl is 10 to 14 B, [10 to 12,J]
In southern Europe T. nitida varies more widely, 11 to 19 (R), 9 to 18 (P), and overlaps with T. reticulata.
5. Labial varix on almost all shells over 15mm high (J, B, P) and additional varix on body whorl occasionally in Britain (J) 51Tr 51 Tritia reticulata album. COMPARISON image of beachworn Tritia nitida. Shell heights 1: 19,4mm. 2: 21.6mm. 3: 26.3mm. Blackwater, Essex, England, September 2019, leg. S.Taylor. , and frequently in Adriatic (P) 50Tr 50 Tritia reticulata album. COMPARISON image of T. nitida. Croatia, Adriatic. © J. Prkić. . In Britain the varix is usually less pronounced than on T. incrassata; sometimes little more than slightly thickened costae, and lost or inconspicuous on some beachworn strandline shells 52Tr 52 Tritia reticulata album. COMPARISON image of beachworn Tritia nitida, 12.9mm high. Blackwater, Essex, England, September 2019, leg. S.Taylor. . Adriatic specimens can have very prominent varices 53Tr 53 Tritia reticulata album. Comparison image of T. nitida. Shell height 40.6mm. Zadar, Croatia. © A. Petani. & 54Tr 54 Tritia reticulata album. Comparison image of T. nitida. Croatia, Adriatic. September 2016. © A. Petani. .
6. Teeth within the outer (palatal) lip quite evenly sized 55Tr 55 Tritia reticulata album. Comparison image of T. nitida. Croatia, Adriatic. September 2016. © A. Petani. , sometimes one a bit higher. “inner [columellar/parietal] lip – – – never tuberculated” (J), but some Adriatic T. nitida have tubercles/teeth on the inner lip 55Tr 55 Tritia reticulata album. Comparison image of T. nitida. Croatia, Adriatic. September 2016. © A. Petani. .
7. “epidermis [periostracum] inconspicuous 57Tr 57 Tritia reticulata album. Comparison image of T. nitida. Locmariaquer, Bretagne, France. March 2019. © P. Boissel. , or obscured by an earthy incrustation 58Tr 58 Tritia reticulata album. COMPARISON of T. nitida. Croatia, Adriatic. © P. Ugarković. ” (J). Shell exterior and interior 59Tr 59 Tritia reticulata album. COMPARISON image of T. nitida. Albania, Adriatic. © A. Golemaj. violaceous (R&S), purplish on yellowish white ground, raised sculpture yellowish white, and coloured lines 57Tr 57 Tritia reticulata album. Comparison image of T. nitida. Locmariaquer, Bretagne, France. March 2019. © P. Boissel. brighter purple than on T. reticulata (J) but presence and intensity of purple varies greatly, often absent or, on beachworn shells, faded (B) 60Tr 60 Tritia reticulata album. COMPARISON image of beachworn Tritia nitida ground open to reveal interior of spire. Blackwater, Essex, England, September 2019, leg. S.Taylor. .
8. In Britain, parietal lip translucent showing shell colour beneath (S & R) 48Tr 48 Tritia reticulata album. COMPARISON images of T. nitida. Shell heights: 12.9mm, 19.4mm, 21.6mm, 26.3mm. Beached shells. Blackwater Estuary, Essex, England. September 2019. Leg. S. Taylor. ; not as extensive, white or distinct as on T. reticulata, but strong and opaque on some T. nitida in Adriatic 53Tr 53 Tritia reticulata album. Comparison image of T. nitida. Shell height 40.6mm. Zadar, Croatia. © A. Petani. & 47Tr 47 Tritia reticulata album. COMPARISON image of large T. nitida from Italian Adriatic. © J. Prkić. . Sometimes eroded or stained on beachworn shells 48Tr 48 Tritia reticulata album. COMPARISON images of T. nitida. Shell heights: 12.9mm, 19.4mm, 21.6mm, 26.3mm. Beached shells. Blackwater Estuary, Essex, England. September 2019. Leg. S. Taylor. .
10. Siphonal canal meets palatal lip at obtuse angle when viewed end-on (R) 61Tr 61 Tritia reticulata album. COMPARISON with Tritia nitida of palatal-lip/siphonal-canal angle. 1 to 4: Blackwater, Essex, England, September 2019, leg. S.Taylor. 5: West Anglesey, Wales, March 2014. . [Beachworn T. reticulata may have angle worn to obtuse and resemble T. nitida 52Tr 52 Tritia reticulata album. COMPARISON image of beachworn Tritia nitida, 12.9mm high. Blackwater, Essex, England, September 2019, leg. S.Taylor. .]
11. Three grooves on columellar neck of siphonal canal 62Tr 62 Tritia reticulata album. Left: T. reticulata, Dorset, England, April 2012. Right: T. nitida, Oosterschelde, Netherlands, June 2017, © S. Verheyen. but eroded from most strandline shells (75% B) and some live shells.
12.Jeffreys (1867) described the body of T. nitida as “greyish, with a slight tinge of purple, and closely speckled with flake-white”. This fits the Bretagne specimen at 63Tr 63 Tritia reticulata album. Comparison image of T. nitida. Locmariaquer, Bretagne, France. March 2019. © P. Boissel. , presumably those from Essex where Jeffreys took his specimens, and some from the Adriatic 58Tr 58 Tritia reticulata album. COMPARISON of T. nitida. Croatia, Adriatic. © P. Ugarković. , but some other Adriatic T. nitida have yellowish bodies 64Tr 64 Tritia reticulata album. Comparison image of T. nitida. Croatia. September 2016. © A. Petani. .The respiratory siphon is “almost always blackish” in Ria de Vigo (R) but both blackish and paler siphons occur on Adriatic T. nitida 58Tr 58 Tritia reticulata album. COMPARISON of T. nitida. Croatia, Adriatic. © P. Ugarković. & 64Tr 64 Tritia reticulata album. Comparison image of T. nitida. Croatia. September 2016. © A. Petani. . The value of flesh and siphon colours for distinguishing T. nitida from T. reticulata elsewhere is uncertain.
13. T. nitida egg capsules are ovoid (R&S) with vertical axis longer 39Tr 39 Tritia reticulata album. Egg capsules. Left: T. reticulata, Anglesey, Wales, May 2016. Right: T. nitida, Oosterschelde, Netherlands, August 2019, © B. van der Sanden. & 65Tr 65 Tritia reticulata album. COMPARISON image of T. nitida egg capsules. Killary Fjord, County Galway, Ireland. June 2018. © M. Thomas. . Mean height 2.65mm, width 1.72mm (R).
14. Sublittoral on muddy substrate in sheltered, variable salinity on Atlantic coasts (S & J). Scattered sites Spain to S. Sweden; more continuous distribution in Mediterranean beyond Barcelona and in Black Sea at variable, often high, salinity (S & R).

Tritia incrassata (Strøm, 1768)
1. Maximum height 12mm.
2. Squatter shell than T. reticulata, adult whorls convex 66Tr 66 Tritia reticulata album. Comparison image of T. incrassata. Dorset, England. April 2012. .
3. Strong, smooth protoconch has c.3 whorls, diameter 0.5 to 0.6mm (Fretter & Graham, 1985), distinctly demarcated from teleoconch. Usually intact, or with only minor damage, when live.
4. Shell sculpture of transverse, oblong, rather than squarish, bosses 66Tr 66 Tritia reticulata album. Comparison image of T. incrassata. Dorset, England. April 2012. .
5. Pronounced, broad, labial varix; light brown when covered by periostracum 66Tr 66 Tritia reticulata album. Comparison image of T. incrassata. Dorset, England. April 2012. ; white, often with transverse red-brown bands when periostracum worn away 67Tr 67 Tritia reticulata album. Comparison image of T. incrassata. Dorset, England. April 2012. .
7. Periostracum only retained in grooves of sculpture on live specimens 66Tr 66 Tritia reticulata album. Comparison image of T. incrassata. Dorset, England. April 2012. .
8. Semicircular, glossy, opaque, white parietal lip covers part of body whorl, less extensive than on T. reticulata 66Tr 66 Tritia reticulata album. Comparison image of T. incrassata. Dorset, England. April 2012. .
9. White columella and siphonal canal 66Tr 66 Tritia reticulata album. Comparison image of T. incrassata. Dorset, England. April 2012. , with distinct brown or black spot inside canal 67Tr 67 Tritia reticulata album. Comparison image of T. incrassata. Dorset, England. April 2012. .
13. Egg capsules small, 1.5mm to 2mm high, similar form to that of T. reticulata, but with longer neck, narrow stalk-base and laid in irregular clumps 68Tr 68 Tritia reticulata album. COMPARISON image of T. incrassata egg capsules. Galicia, Spain. July 2018. © C. Fernández-Cid. (image in Lebour, 1931, plymsea.ac.uk/id/eprint/697/ ).
14. Rocky shores all round Britain. Lower shore and sublittoral.

Tritia pygmaea (Lamarck, 1822)
1. Maximum height 14mm.
2. Squatter shell than T. reticulata, adult whorls convex 69Tr flic.kr/p/2hF4WhS .
3. Smooth protoconch has 2.25 whorls , diameter 750 to 950µ (Fretter & Graham, 1985), nearly as large as on the much larger shell of T. reticulata 70Tr 70 Tritia reticulata album. Comparison image of T. varicosa (formerly pygmaea). Shell height 10.5mm. In crab pot. Sussex, England. April 2011. Leg. K. Fraussen. coll. S. Taylor. .
4. Widely-spaced, narrow costae intersect with narrowly-spaced, narrow spiral ridges to form small, rounded bosses 69Tr flic.kr/p/2hF4WhS . All sculpture is well-raised on unweathered shells.
5. Pronounced labial varix on adult shells, and most have one or more additional varix on body-whorl or spire whorls. Varices usually white with transverse brown bands 69Tr flic.kr/p/2hF4WhS .
7. Shell glossy with no obvious periostracum when live.
9. Columellar lip orange-brown. Often orange-brown at entrance of siphonal canal, but no black or blackish brown further within canal 70Tr 70 Tritia reticulata album. Comparison image of T. varicosa (formerly pygmaea). Shell height 10.5mm. In crab pot. Sussex, England. April 2011. Leg. K. Fraussen. coll. S. Taylor. .
10. Viewed end on, rounded siphonal canal meets palatal lip at an acute angle 70Tr 70 Tritia reticulata album. Comparison image of T. varicosa (formerly pygmaea). Shell height 10.5mm. In crab pot. Sussex, England. April 2011. Leg. K. Fraussen. coll. S. Taylor. .
14. South and west coast of Britain to Shetland. Not Irish Sea. Sublittoral, 1m to 200m, sandy substrate; found on bait in crab pots.