02 Tritia reticulata

Adult shell is a fairly tall, sharply pointed cone; width about 45% of height. Juveniles are more squat and taper more sharply; W/H about 55%.

Body-whorl convex. Spire-whorls have almost straight-sided profile on adult (1); slightly concave on juvenile (2).

Height 27.6 mm, Dorset, April 2012 and juvenile (at larger scale) height 5.6 mm, west Anglesey, Wales, May, 2016.

Full SPECIES DESCRIPTION BELOW

PDF available at: www.researchgate.net/publication/378125315_Tritia_reticul...

Sets of OTHER SPECIES:

www.flickr.com/photos/56388191@N08/collections/

 

Tritia reticulata (Linnaeus, 1758)

 

Synonyms: Buccinum reticulatum Linnaeus, 1758; Hinia reticulata (Linnaeus, 1758); Nassarius reticulatus (Linnaeus, 1758); Nassa reticulata (Linnaeus, 1758).

Current taxonomy: World Register of Marine Species (WoRMS)

www.marinespecies.org/aphia.php?p=taxdetails&id=876821

Vernacular: Netted dog whelk (English); Chwalcen rwyllog (Welsh); Gevlochten fuikhoren (Dutch); Netzreusenschnecke (German); Nasse réticulée (French); Dværgkonk (Danish); Κοφίνι (Greek).

 

GLOSSARY below.

 

Shell description.

The shell of T. reticulata grows to a maximum of 30 mm high and 14 mm wide. The shell wall is solid, opaque and matt. The body whorl is convex but the spire whorls are almost flat and the spire profile is almost straight sided 1Tr flic.kr/p/2hF1X7i . Juveniles may have a slightly concave spire profile 2Tr flic.kr/p/2hF31A1 . The sutures are shallow, but are sometimes emphasised by each whorl being raised slightly higher than the preceding whorl 1Tr flic.kr/p/2hF1X7i . The spire is a variably slender, sharply pointed cone with adult width varying from 45% to 55% of height 1Tr flic.kr/p/2hF1X7i . Juvenile spires taper more sharply with width/height about 55%, or more 2Tr flic.kr/p/2hF31A1 . Adult body whorl height is 60% to 70% of shell height 3Tr flic.kr/p/2hF31sa . The shell has a sculpture of broad spiral ridges, narrower spiral grooves, and sigmoid costae about as wide as the intervening gaps. In Britain, the adult body whorl has 15 to 23 costae (pers. obs. IFS, 2019) or 15 to 20 (Jeffreys, 1867). In Ria de Vigo, north-west Spain, 16 to 23 costae were recorded by Rolan and Luque (1994). Juveniles may have more costae. Rarely, the final costa is sufficiently thickened to form a slight labial varix 4Tr flic.kr/p/2hEYddy. The exterior rim of the aperture is usually thin, smooth and white without periostracum 5Tr flic.kr/p/2hEYcRG & 6Tr flic.kr/p/2hEYcJx . The intersection of costae and spiral ridges creates rectangular bosses in a reticulate arrangement 7Tr flic.kr/p/2hEYcFB . There is a deep spiral gutter at the base of the shell. Below the gutter, the neck of the siphonal canal has 4 or 5 grooves on its exterior when not eroded 7Tr flic.kr/p/2hEYcFB . The protoconch has a diameter of about 1 mm and is smooth and white 8Tr flic.kr/p/2hF2ZuP with a little more than 2 whorls (Sanjuan, 1997). In Ria de Vigo, Sanjuan (1997) found this to differentiate it from T. nitida with a little less than two complete whorls, but some in Britain seem to have 1.8 whorls on the protoconch 9Tr flic.kr/p/2hF2Ztr . In the Ria de Vigo, Sanjuan (1997) found the protoconch to persist on most live T. reticulata and to be incomplete on most T. nitida. This applied generally also to British material examined by IFS, the apical whorls being frequently broken off on T. nitida and often persisting to form a fine point, even when worn, on T. reticulata10Tr flic.kr/p/2hEYcvS . When live and uneroded, the exterior of the shell is covered by a brown periostracum apart from the protoconch and the rim of the outer (palatal) lip 5Tr flic.kr/p/2hEYcRG . On worn shells the periostracum persists longest in the shelter of the grooves between the costae and spiral ridges 11Tr flic.kr/p/2hF1VBE .

The height of the oval aperture is about 45% of the shell height 3Tr flic.kr/p/2hF31sa . The palatal (outer) lip meets the parietal (upper, inner) lip at about 90º (not always discernible) but immediately curves strongly abapically so the aperture is pointed adapically12Tr flic.kr/p/2hF2Zpi . Sometimes there is a small anal sinus. At the base of the shell, the distal end of the short, oblique, widely-open siphonal canal meets the palatal lip at a slightly-acute or right angle when viewed end-on13Tr flic.kr/p/2hF1VqY & 14Tr flic.kr/p/2hF2Z9U . The short, straight, white, exposed columella forms one side of the canal. The siphonal canal of earlier stages remains as a deep groove on the columella concealed within the spire for its entire length to the apex of the shell 15Tr flic.kr/p/2hF2Z4P . The substantial, opaque, glossy white, semicircular parietal lip spreads extensively over the body whorl 12Tr flic.kr/p/2hF2Zpi . It may be stained by epizooic growth16Tr flic.kr/p/2hF1V5C . The porcelaneous (when live or recently dead) white aperture interior rapidly thickens away from the thin palatal rim and, on adults, forms a rib with 6 to 10 unevenly sized palatal teeth. The one or two near the middle are often the most prominent 12Tr flic.kr/p/2hF2Zpi . Frequently there are up to six less conspicuous columellar/parietal teeth 17Tr flic.kr/p/2hF2YUR . The external ground colour of the shell is brownish when the periostracum is intact, but opaque, matt whitish/buff when the periostracum is eroded 7Tr flic.kr/p/2hEYcFB . Exposed shell may be stained by epizoic growth 16Tr flic.kr/p/2hF1V5C . Spire whorls may have a brown or purple-brown subsutural line, and the body whorl may have a similar line on its periphery and another above the spiral gutter18Tr flic.kr/p/2hEYbT4 . The small, oval, translucent, horn-coloured operculum19Tr flic.kr/p/2hEYbQP has a distal (outer) surface of conchiolin with concentric growth rings round a peripheral nucleus. The proximal (inner) surface has a matt surface where the opercular disc attaches to it, with concentric lines running transversely to exterior growth lines. The unattached part of the proximal surface is of varnish without growth lines.

Body description

The ground colour of most parts of the body is usually light sienna or yellowish 11Tr flic.kr/p/2hF1VBE or, on juveniles, whitish20Tr flic.kr/p/2hEYbJr , heavily marked with small white and brown/black marks. It is uncertain whether grey bodies are confined to T. nitida, as stated by Jeffreys (1867). The rectangular head is dorsoventrally flattened with a long, slender, tapering cephalic tentacle on each anterior corner 21Tr flic.kr/p/2hF1ULS . There is a small, black eye on the swollen base of each tentacle. There is no external snout between the tentacles, but the ventral surface of the head has a slit opening (pseudo-mouth) 22Tr flic.kr/p/2hF2Yvu of a sac containing the retracted, long, unmottled, pleurembolic 23Tr flic.kr/p/2hF2Yqz proboscis 24Tr flic.kr/p/2hF1Uv1 & 25Tr flic.kr/p/2hF1UkX . The radula, buccal mass and the true mouth are in the distal end of the proboscis. The rachiglossan radula has in each row of colourless, transparent teeth a wide, central, rachidian tooth with many small cusps (points) flanked on either side by a longer marginal tooth 26Tr flic.kr/p/2hF2Y4Y . The yellow mantle lacks mottling at the anterior of the mantle cavity 16Tr flic.kr/p/2hF1V5C , but it has much dark pigment further back 27Tr flic.kr/p/2hF1Ueu . The mantle on the left extends as contractile, densely mottled, respiratory siphon through, and often far beyond, the siphonal canal of the shell 28Tr flic.kr/p/2hEYb29 . The mantle can extend widely onto the body whorl exterior to deposit the wide, glossy white parietal lip 16Tr flic.kr/p/2hF1V5C . Within the mantle cavity, behind the right tentacle, males have a large, curved, buff-white penis with only a few dark marks basally 29Tr flic.kr/p/2hEYaXB & 30Tr flic.kr/p/2hEYaTo . Also in the mantle cavity (dissection required) there are a large, yellow-brown, pinnate ctenidium and a large, pinnate, red-brown osphradium resembling a ctenidium in structure 31Tr flic.kr/p/2hF2XMA .

The large, broad, ovoid foot 32Tr flic.kr/p/2hEYaPF is truncate at the anterior with angulated corners (propodial tentacles) that can be varied from bluntly rounded 33Tr flic.kr/p/2hF1TLq to recurved and sharply pointed 34Tr flic.kr/p/2hEYaAu . The anterior and corners of the foot are deeply bilaminate 35Tr flic.kr/p/2hF1Tv5 with the anterior pedal mucus gland within. In life, the bilaminate groove is often concealed by the upper lamina overhanging it. The posterior of the foot narrows to a blunt point with a pair of small metapodial tentacles dorsally 5Tr flic.kr/p/2hEYcRG . The foot can transform to a variety of shapes, and twist abruptly to different positions 36Tr flic.kr/p/2hF2nse . Dorsally the foot is coloured as most of the body 32Tr flic.kr/p/2hEYaPF but on the sole white marks are usually limited to near the edge 6Tr flic.kr/p/2hEYcJx .

 

The dissected female in images 27Tr flic.kr/p/2hF1Ueu (mantle intact) , 24Tr flic.kr/p/2hF1Uv1 (mantle cut and opened to right, but remaining on part of the mantle cavity) and 25Tr flic.kr/p/2hF1UkX (body wall opened) , shows the following features:

1: sole of foot. 2: dorsum of foot. 3: cephalic tentacle.

4: operculum. 5: mantle edge. 6: unblotched mantle.

7: darkly blotched mantle. 8: respiratory inhalent siphon.

9: osphradium for testing inhalent water. 10: ctenidium (gill).

11: hypobranchial gland, secretes mucus to trap particles from inhalent water.

12: kidney. 13: digestive gland. 14: stomach. 15: ovary.

16: auricle of heart. 17: ventricle of heart.

18: proboscis sheath seen through translucent body wall.

19: proboscis with sheath removed. 20: ova.

 

Key identification features

Identification should be made using a combination of features as some elements may vary.

Tritia reticulata

1) Maximum height 30 mm.

2) Spire variably slender, flat-sided, sharply pointed cone with almost flat whorls on spire and shallow suture 1Tr flic.kr/p/2hF1X7i (Body whorl convex). Juveniles are more squat, taper more sharply and may have a slightly concave-sided spire 2Tr flic.kr/p/2hF31A1.

3) Smooth protoconch, c.1 mm diameter, usually persists to form a fine, sharp apex 8Tr flic.kr/p/2hF2ZuP , even when worn10Tr flic.kr/p/2hEYcvS .

4) Costae (axial ribs) intersect with spiral ridges to create reticulate arrangement of squarish bosses 7Tr flic.kr/p/2hEYcFB . In Britain, number of costae on body whorl is 15 to 23 (pers. obs. IFS), (15 to 20 in Jeffreys, 1867) and, in Ria de Vigo, Spain, 16 to 23 (Rolan and Luque, 1994).

5) Only very rarely, is the final costa sufficiently thickened to form a slight labial varix 4Tr flic.kr/p/2hEYddy .

6) Teeth within the outer (palatal) lip are unevenly sized, one or two near middle often most prominent 12Tr flic.kr/p/2hF2Zpi . The inner (columellar and parietal) lip is “more or less tuberculated” (Jeffreys, 1867), but teeth/small ribs may be absent, especially on young ones.

7) When live and unworn, a brown periostracum covers the shell except the protoconch and white rim of outer (palatal) lip 5Tr flic.kr/p/2hEYcRG . When the periostracum is removed, the shell exterior is matt whitish/buff 7Tr flic.kr/p/2hEYcFB , unless stained by epizooic growth or other matter16Tr flic.kr/p/2hF1V5C . Interior is glossy white 3Tr flic.kr/p/2hF31sa .

8) Semicircular, glossy, opaque, white parietal lip covers large part of body whorl 12Tr flic.kr/p/2hF2Zpi ; may be stained by epizooic growth or other matter16Tr flic.kr/p/2hF1V5C .

9) White columella and siphonal canal. No dark spot within canal 3Tr flic.kr/p/2hF31sa .

10) Siphonal canal meets palatal lip at slightly-acute or right angle when viewed end-on 13Tr flic.kr/p/2hF1VqY . Beachworn specimens may have angle worn to obtuse and resemble T. nitida 37Tr flic.kr/p/2hF69i4 .

11) 4 to 5 grooves on columellar neck of siphonal canal 7Tr flic.kr/p/2hEYcFB [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 flic.kr/p/2hF1VBE & 38Tr flic.kr/p/2hF559d .]

12) Body flesh light sienna/yellowish 11Tr flic.kr/p/2hF1VBE (juveniles, whitish 20Tr flic.kr/p/2hEYbJr ), 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 flic.kr/p/2hF68jk . Mean height 4.07 mm, width 3.25 mm, W/H 80% including neck (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 in Smith (2019). Populations vary geographically, so some features may not match those below. They are marked (J) for Thames, Orwell and Roach estuaries in S.E. England in Jeffreys (1867); (B) for a 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 25 mm (J), exceptionally (2% of strandline sample) 26 to 30 mm (B) 46Tr flic.kr/p/2hF659n , 30 mm in Galicia, Spain (Trigo et al., 2018) and 40 mm in the Italian Adriatic (P) 47Tr flic.kr/p/2hF64Ld .

2) Adult T. nitida spire-whorls convex in Essex 46Tr flic.kr/p/2hF659n & 48Tr flic.kr/p/2hF2hwY . 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 flic.kr/p/2hF63Tw .

3) Smooth protoconch is frequently worn/broken off to give a blunt apex 48Tr flic.kr/p/2hF2hwY but it appears to persist more on Mediterranean T. nitida 50Tr flic.kr/p/2hF63Tw .

4) In Britain, number of costae on body whorl is 10 to 14 B 56Tr flic.kr/p/2puu5Fz , [10 to 12,J]

In southern Europe T. nitida varies more widely, 11 to 19 (R), 9 to 18 (P) 56Tr flic.kr/p/2puu5Fz, and overlaps with T. reticulata when 15 or more costae.

5) Labial varix on almost all shells over 15 mm high (J, B, P) and additional varix on body whorl occasionally in Britain (J) 51Tr flic.kr/p/2hF63vn , and frequently in Adriatic (P) 50Tr flic.kr/p/2hF63Tw . 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 flic.kr/p/2hF62Ww . Adriatic specimens can have very prominent varices 53Tr flic.kr/p/2hF62Mi & 54Tr flic.kr/p/2hF2fMW .

6) Teeth within the outer (palatal) lip quite evenly sized 55Tr flic.kr/p/2hF4XZE , 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 flic.kr/p/2hF4XZE .

7) “epidermis [periostracum] inconspicuous 57Tr flic.kr/p/2hF4XKw , or obscured by an earthy incrustation 58Tr flic.kr/p/2hF4XDK ” (Jeffreys, 1867). Shell exterior and interior 59Tr flic.kr/p/2hF4XvZ violaceous (R&S), purplish on yellowish white ground, raised sculpture yellowish white, and coloured lines 57Tr flic.kr/p/2hF4XKw brighter purple than on T. reticulata (J) but presence and intensity of purple varies greatly, often absent or, on beachworn shells, faded (B) 60Tr flic.kr/p/2hF4Xum .

8) In Britain, parietal lip translucent showing shell colour beneath (S & R) 48Tr flic.kr/p/2hF2hwY ; not as extensive, white or distinct as on T. reticulata, but strong and opaque on some T. nitida in Adriatic 53Tr flic.kr/p/2hF62Mi & 47Tr flic.kr/p/2hF64Ld . Sometimes eroded or stained on beachworn shells 48Tr flic.kr/p/2hF2hwY .

10) Siphonal canal meets palatal lip at obtuse angle when viewed end-on (R) 61Tr flic.kr/p/2hF4Xij . [Beachworn T. reticulata may have angle worn to obtuse and resemble T. nitida 52Tr flic.kr/p/2hF62Ww .]

11) Three grooves on columellar neck of siphonal canal 62Tr flic.kr/p/2hF61Ak 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 flic.kr/p/2hF2ezL , presumably those from Essex where Jeffreys took his specimens, and some from the Adriatic 58Tr flic.kr/p/2hF4XDK , but some other Adriatic T. nitida have yellowish bodies 64Tr flic.kr/p/2hF61oB .The respiratory siphon is “almost always blackish” in Ria de Vigo (R) but both blackish and paler siphons occur on Adriatic T. nitida 58Tr flic.kr/p/2hF4XDK & 64Tr flic.kr/p/2hF61oB . The value of flesh and siphon colours for distinguishing T. nitida from T. reticulata elsewhere is uncertain.

13) T. nitida egg capsules are slenderly ovoid (R&S) with W/H 65% including neck 39Tr flic.kr/p/2hF68jk & 65Tr flic.kr/p/2hF4WFT . Mean height 2.65 mm, width 1.72mm (R) W/H 65%.

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). In Britain and Ireland there are records from East Anglia, Essex, Southampton Water and Galway, and it probably exists in other sheltered waters.

 

Tritia incrassata (Strøm, 1768)

1) Maximum height 12 mm.

2) Squatter shell than T. reticulata, adult whorls convex 66Tr flic.kr/p/2hF61bC .

3) Strong, smooth protoconch has c.3 whorls, diameter 0.5 to 0.6 mm (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 flic.kr/p/2hF61bC .

5) Pronounced, broad, labial varix; light brown when covered by periostracum 66Tr flic.kr/p/2hF61bC ; white, often with transverse red-brown bands when periostracum worn away 67Tr flic.kr/p/2hF4WmV .

7) Periostracum only retained in grooves of sculpture on live specimens 66Tr flic.kr/p/2hF61bC .

8) Semicircular, glossy, opaque, white parietal lip covers part of body whorl, less extensive than on T. reticulata 66Tr flic.kr/p/2hF61bC .

9) White columella and siphonal canal 66Tr flic.kr/p/2hF61bC , with distinct brown or black spot inside canal 67Tr flic.kr/p/2hF4WmV (often hidden in photographs by shadow, the siphon or the tilt of the pose).

13) Egg capsules small, 1.5 mm to 2 mm high, similar form to that of T. reticulata, but with longer neck, narrow stalk-base and laid in irregular clumps 68Tr flic.kr/p/2hF4WjR (image in Lebour, 1931, plymsea.ac.uk/id/eprint/697/ ).

14) Rocky shores all round Britain. Lower shore and sublittoral.

 

Tritia varicosa (W. Turton, 1825)

1) Maximum height 14 mm.

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 flic.kr/p/2hF2djp .

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 varices 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 flic.kr/p/2hF2djp .

10) Viewed end on, rounded siphonal canal meets palatal lip at an acute angle 70Tr flic.kr/p/2hF2djp .

14) South and west coast of Britain to Shetland. Not Irish Sea. Sublittoral, 1 m to 200 m, sandy substrate; found on bait in crab pots.

 

Habits and ecology

T. reticulata lives in full marine salinity at LWS on shores with mixed hard and sandy substrate at spots where organic remains accumulate, and on sandy substrate to about 35 metres sublittorally. Large congregations may occur on carrion 40Tr flic.kr/p/2hF54pY . Reports of it in brackish water >16‰ on muddy substrate may be of unrecognized T. nitida, which also lives at high salinity in the Mediterranean. At low tide on shores, pools and runnels are favoured or shelter is taken under rocks or below wet sediment with the respiratory siphon protruding. The siphon tip may have photoreceptors as it withdraws when shadow falls on it.

Sublittorally, it remains hidden in the surface layer of sediment with its inhalent siphon tip protruding for much of the time, emerging promptly when carrion or faeces are sensed by its large osphradium and gliding rapidly to it on its broad foot lubricated with mucus from the anterior pedal gland. Many assemble like vultures 49Tr flic.kr/p/2hF4Znp and push their proboscises, 150% length of shell at full extension, deep into carrion while holding their long siphons away from it to inhale uncontaminated water 40Tr flic.kr/p/2hF54pY . The sucker-like tip enables the proboscis to retain feeding position while the radula rasps 25Tr flic.kr/p/2hF1UkX . The faeces are oval pellets.

The strong shells of adults resist crab attack, but many beached, thin, juvenile shells have broken lips which may indicate successful crab predation 41Tr flic.kr/p/2hF67jp . Predatory Euspira spp. may bore the shells of juvenile T. reticulata near the apex where thinnest, but below the persistent protoconch 42Tr flic.kr/p/2hF52J3 &15Tr flic.kr/p/2hF2Z4P . When starfish attack, T. reticulata reacts immediately to first touch by vigorously twisting and turning its body and shell in different directions to confuse the attacker 36Tr flic.kr/p/2hF2nse .

It breeds from March to August at Plymouth, and from April to August further east in the English Channel (Fretter & Graham, 1985). The female inspects potential ovipositing sites of rock, shell, Zostera or alga; with the tip of her siphon, and may clean the surface with its radula before laying capsules containing 50 to 350 orange-pink 43Tr flic.kr/p/2hF66ey or white 44Tr flic.kr/p/2hF2jaH ova in each. The capsule passes along a temporary groove in the foot to the female ventral pedal gland 36Tr flic.kr/p/2hF2nse which grips it and forms it into a flattened, brandy-bottle shape with a circular chamber, flat on one face and slightly convex on the other. The small base is secured in position on a large disc of cement. The mean capsule size, including apical neck, is 4.07 mm high and 3.25 mm width W/H 80% (Rolan & Luque, 1994). The capsule and fluid around the ova are transparent colourless. Initially, ova fill less than half of the capsule but by the end of one to two months’ development the capsule has broadened c.20% and ova have grown to fill it 39Tr flic.kr/p/2hF68jk . Capsules are often laid in rows like books on a shelf all leaning at c.50° 43Tr flic.kr/p/2hF66ey . Hatched, free-swimming veligers escape through the now unplugged apical neck of the capsule. Veligers have a transparent, smooth shell of 1.5 whorls, c. 300µ long. The bilobed velum has a marginal brown line, and the sole is red-brown. After two to three 3 months in the plankton (mainly June to September, with a few January to March, at Plymouth), it metamorphoses to a three whorled, c.750µ, shell with siphonal canal (Fretter & Graham, 1985; may include data of T. nitida).

 

Distribution and status

T. reticulata sensu stricto lives along Atlantic coasts from Norway to Morocco and into the Mediterranean only as far east as Oran, Algeria and 23km north-east of Barcelona, being replaced further east and into the Black Sea by T. nitida (Rolan and Luque, 1994). Images of T. reticulata sensu stricto on iNaturalist at www.inaturalist.org/observations/168276172 show that it occurs further east to near Marseille, France. The Norwegian marine gastropod list by Høisæter (2009) omits T. reticulata sensu stricto, but images from Norway by E. Svensen show that it is present 45Tr flic.kr/p/2hF52h1 & 40Tr flic.kr/p/2hF54pY . The GBIF map www.gbif.org/species/5727892 for T. reticulata should be regarded as showing distribution of an aggregate with T. nitida. T. reticulata is common all round Britain and Ireland, except scarce or absent from Fife to Caithness, and there are few records from Suffolk, Lincolnshire and Cumbria. Those in sheltered muddy estuaries need careful examination as T. nitida occurs commonly in Essex, in Southampton Water and Galway, and probably in other sheltered waters. U.K. interactive map NBN (aggregated with T. nitida) records.nbnatlas.org/occurrences/search?q=lsid:NHMSYS0021...

 

Acknowledgements

I am indebted to Philippe Boissel, Carlos Fernández-Cid, Joe FitzGibbon, Aleksander Golemaj, Alen Petani, Bas van der Sanden, Erling Svensen, Mark Thomas, Pero Ugarković, Stefan Verheyen and Neil Ward for use of their informative images, to Miquel Pontes for providing vital literature, and to Julia Nunn, Jakov Prkić and Vollrath Wiese for information and advice. Special thanks are due to my co-author, Simon Taylor, for undertaking shore visits and supplying specimens for this account, and to Jakov Prkić for taking many images specifically for this account.

 

Links and references

 

Chaster, G.W., Knight, G.A.F., Melvill, J.C. and Hoyle, W.E. 1901. List of British marine mollusca and brachiopoda. Manchester, Conchological Society of Great Britain and Ireland. archive.org/details/listofbritishmol00chas/page/n21/mode/2up

 

Collins, K.S., Edie, S.M., Gao, T., Bieler, R. and Jablonski, D. 2019. Spatial filters of function and phylogeny determine morphological disparity with latitude. PLoSONE 14 (8): e0221490. doi.org/10.1371/journal.pone.0221490

 

Collyer, D.M. 1961. Differences revealed by paper partition chromatography between the gastropod Nassarius reticulatus (L.) and specimens believed to be N. nitida (Jeffreys). J. Mar. Biol. Ass. 41(3): 683 to 693.

plymsea.ac.uk/id/eprint/2150/1/Differences_revealed_by_pa...

 

Couceiro, L., López, L., Sotka, E.E., Ruiz, J.M. & Barreiro, R. 2012. Molecular data delineate cryptic Nassarius species and characterize spatial genetic structure of N. nitidus. J. Mar. Biol. Ass. 92(5): 1175 to 1182. www.researchgate.net/publication/230846249_Molecular_data...

 

Diz, P., Jorissen F. J., Reichart, G. J., Poulain, C., Dehairs, F., Leorri E. and Paulet, Y.-M.

Interpretation of benthic foraminiferal stable isotopes in subtidal estuarine environments. Biogeosciences, 6, 2549–2560, 2009 www.biogeosciences.net/6/2549/2009/

 

Forbes, E. & Hanley S. 1849-53. A history of the British mollusca and their shells. vol. 3 (1853), London, van Voorst. (As Nassa reticulata) archive.org/stream/historyofbritish03forbe#page/388/mode/...

 

Fretter, V. and Graham, A. 1985. The prosobranch molluscs of Britain and Denmark. Part 8 – Neogastropoda. Suppl. 15, J. Moll. Stud.

 

Graham, A. 1988. Molluscs: prosobranch and pyramidellid gastropods. Synopses of the British Fauna (New Series) no.2 (Second edition). Leiden, E.J.Brill/Dr. W. Backhuys. 662 pages.

 

Hayward, P.J. & Ryland, J.S. (eds.) 1995. Handbook of the marine fauna of North-West Europe. Oxford University Press.

 

Høisæter, T. (2009). Distribution of marine, benthic, shell bearing gastropods along the Norwegian coast. Fauna Norvegica, 28: 5-106. doi.org/10.5324/fn.v28i0.563

 

Jeffreys, J.G. 1862-69. British conchology. vol. 4 (1867). London, van Voorst. (As Nassa reticulata) p346 in pdf archive.org/stream/britishconcholog04jeffr#page/346/mode/2up .

Original description of T. nitida (as Nassa nitida) on p349 at archive.org/stream/britishconcholog04jeffr#page/348/mode/2up

 

Lebour, M. V. 1931. The larval stages of Nassarius reticulatus and Nassarius incrassatus. J. Mar. Biol. Ass., 17 (3). 797-818. plymsea.ac.uk/id/eprint/697/

 

Linnaeus, C. (1758). Systema Naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Editio decima, reformata [10th revised edition], vol. 1: 824 pp. Laurentius Salvius: Holmiae. www.biodiversitylibrary.org/page/726886#page/762/mode/1up entry 411 p. 740

 

Marshall, J. T. 1895. Alterations in ‘British Conchology’. J. Conch. 8: 24 to 41.

www.biodiversitylibrary.org/item/99811#page/60/mode/1up [p38 as Nassa nitida]

 

McKay, D.W. & Smith, S.M. 1979. Marine Mollusca of East Scotland. Edinburgh, Royal Scottish Museum.

 

McClelland, H. 1926. General index of all families, genera, species and varieties described and noted in the Journal of Conchology vols. I – XVI, 1874 to 1922. Proceedings of the Malacological Society of London vols. I – XV, 1893 to 1923. The Conchologist vols I – II, 1891 to 1893, continued as the Journal of Malacology vols. III – XII, 1894 to 1905. Birmingham, Birbeck and sons.

 

McMillan, N.F. 1968. British shells. London, F.Warn.

 

Rolan, E. and Luque, A.A. 1994. Nassarius reticulatus (Linnaeus, 1758) and Nassarius nitidus (Jeffreys, 1867) (Gastropoda, Nassariidae), dos especies válidas de los mares de

Europa. Iberus, 12 (2): 59-76. www.biodiversitylibrary.org/part/98444

 

Sanjuan, A., Pérez-Losada, M. & Rolan, E. 1997. Allozyme evidence for cryptic speciation in sympatric populations of Nassarius spp. (Mollusca: Gastropoda). J. Mar. Biol. Ass. 77(3): 773 to 784.

 

Smith, I.F. 2019. Differentiation of Tritia reticulata (Jeffreys, 1867) from Tritia reticulata (Linnaeus, 1758). Mollusc World Issue 51. Expanded pdf version at www.researchgate.net/publication/336441072_Recognition_of...

 

Trigo, J.E.; Diaz Agras, G.J.; Garcia Alvarez, O.L.; Guerra, A.; Moreira, J.; Pérez, J.; Rolán, E.; Troncoso, J.S,; Urgorri, V.. 2018. Guia de los Moluscos Marinos de Galicia. Servicio de Publicacións da Universidade de Vigo.

 

Turton, W. 1825. Description of some new British shells. Zoological Journal, 2: 361-367. [Fist description of Tritia varicosa as Tritonia varicosa]. www.biodiversitylibrary.org/page/2255625#page/431/mode/1up

 

Yonge, C.M. and Thompson, T.E. 1976. Living marine molluscs. Collins, London. [Fig. 52G shows Danish egg capsules of T. nitida labelled as Nassarius reticulatus.]

 

 

Glossary

acrembolic = (of proboscis) introversible/eversible like finger of glove.

adapical = towards the apex of the shell.

anal sinus = notch in adapical angle of aperture; route of rectum/anus to exterior of shell.

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

bilaminate = (adj.) formed of two layers.

cephalic = (adj.) of or on the head.

cilia = (pl.) vibrating linear extensions of membrane used in locomotion..

ciliated = (adj.) coated with cilia.

coll. = (or “in coll.”, abbreviation of “in collectionem”) in the collection of (named person or institution; c.f. leg.).

 

columella = axis of gastropod shell spiral, exposed on final whorl by aperture.

columellar = (adj.) of or near central axis of spiral gastropod.

columellar lip = lower (abapical) part of inner lip of aperture.

costa = (pl. costae) axial rib crossing shell whorl at about right-angles to any spiral striae.

costal = (adj.) of, or arranged like, costae.

ctenidium = comb-like molluscan gill; usually an axis with filaments either side.

cusp = raised point or prominence on crown of a tooth.

distal = away from centre of body or from point of attachment.

dorsoventrally flattened = as if pressed flat from above.

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

height = (of gastropod shells) distance from apex of spire to base of aperture.

hypobranchial gland = thickened, sometimes puckered, tissue on roof of mantle cavity of many gastropods. Secretes mucus to trap and consolidate particles from inhalent water. Often other biologically active compounds produced.

 

labial varix = especially strong or broad costa (rib) along edge of outer lip of aperture.

leg. = (abbreviation of legit) collected/ found by (c.f. coll.)

LWS = low water spring tide, two periods of a few days each month when tide falls lowest.

mantle = sheet of tissue that secretes shell and forms a cavity for the gill in most marine molluscs.

metapodial = (adj.) of the hind part of the foot.

odontophore = tongue-like structure of cartilage supporting radula.

opercular = (adj.) of the operculum.

operculum = plate of horny conchiolin, rarely calcareous, used to close shell aperture.

osphradium = organ for testing water for pollutant, prey or predator chemicals and/or for particles.

periphery = ‘equator’ of gastropod body whorl, sometimes with a keel or coloured band.

periostracum = thin horny layer of chitinous material often coating shells.

pers. comm. = personal communication by face-to-face conversation, telephone, letter or email.

plankton = animals and plants that drift in pelagic zone (main body of water).

pleurembolic proboscis = basal part (only) of proboscis inverts to form a sac for rest of proboscis to be retracted into without inversion. (c.f. acrembolic).

 

porcelaneous = resembling vitreous glazed ceramic material.

protoconch = apical whorls produced during embryonic and larval stages; different in form from other whorls forming teleoconch.

 

proximal = towards the centre of the body or point of attachment.

rachidian = (adj.) median/middle tooth in each row of teeth on radula.

rachiglossan = (adj.) of radula with a many-cusped, rachidian tooth, and single marginal tooth at each side.

 

radula = chitinous ribbon of teeth; extended on odontophore to rasp food.

sigmoid = curved in two directions like letter ‘S’ but often with shallower curvature.

subsutural = close below the suture when shell positioned with apex uppermost.

sutural = (adj.) of or close to a suture.

suture = groove or line where whorls of gastropod shell adjoin.

teleoconch = entire gastropod shell, apart from apical protoconch.

varix = (see labial)

veliger = shelled larva of marine mollusc; swims by waving cilia on velum (bilobed flap).

 

Done