Cystiscus is a taxonomic genus of minute sea snails, marine gastropod mollusks or micromollusks.
This genus was placed in the family Cystiscidae by Coovert and Coovert, 1995. Previously the genus was in the family Marginellidae, where it is still placed by many other malacologists.
Diagnosis Shell minute to small, white, hyaline; spire immersed to low; lip thickened, smooth or weakly denticulate; external varix absent; siphonal notch absent; posterior notch absent; lacking collabral parietal callus ridge; columella multiplicate, with combined usually 2 to 8 plications plus parietal lirae, first plication usually strong and raised. Mantle smooth, at least partially extending over external shell surface.
Shell description Shell minute to small (adult length ). Color white, hyaline; surface smooth, glossy. Shape usually elliptic, obovate, or subtriangular; weakly shouldered. Spire completely immersed to low. Aperture narrow to broad, usually wider anteriorly. Lip slightly to distinctly thickened, flared posteriorly in some species, smooth on inside edge to weakly denticulate, lacking lirae, external varix absent. Shell lacking a siphonal notch and posterior notch. Shell with weak parietal callus wash or weak parietal callus deposits in some species, but lacking collabral parietal callus ridge. Columella multiplicate, with combined total 2 to 8 plications plus parietal lirae, rarely to 17 in which the posteriormost are denticles; one species with only 1 plication. Plications usually occupying less than half the length of the aperture, but most of the aperture in some. Plications excavated just inside aperture in a few species, usually evenly rounded, first plication usually raised and very strong. Shell with cystiscid internal whorls.
Animal anatomy Internal: Unknown External: Animal with eyes at side of head, usually on lateral swelling; mantle smooth, at least partially extending onto external shell surface, in some species nearly covering shell; foot relatively narrow, about as wide as shell length; head and mantle usually uniformly colored, often bright red, orange, or yellow, or brown, or black, internal mantle color pattern often showing through translucent shell. Radula: Uniserial, ribbon long, narrow, composed of 80-209 plates. Rachidian plates overlapping, narrow, moderately to strong arched, with 6-14 sharp cusps on posterior edge, the central cusp usually the strongest. The anterior edge of the rachidian plate is strongly concave, resulting in U- or V-shaped plates.
Habitat Intertidal to .
Fossil record Eocene of France and Alabama, upper Oligogene and Miocene of Western Atlantic, to Recent.
Remarks The two halves of the head are capable of closing together at will, thus appearing unsplit. The long siphon usually distinguishes this group from Gibberula. The shell of Persicula is usually patterned, often has a distinct external varix, and the spire is usually immersed. These conchological features serve to separate the two groups.
Species Cystiscus contains the following accepted species:
Cystiscus angasi (Crosse, 1870) Cystiscus aphanacme (Tomlin, 1918) Cystiscus aurantius Boyer, 2003 Cystiscus beqae Wakefield & McCleery, 2006 Cystiscus boucheti Boyer, 2003 Cystiscus bougei (Bavay, 1917) Cystiscus bucca (Tomlin, 1916) Cystiscus caeruleus Boyer, 2003 Cystiscus camelopardalis Boyer, 2003 Cystiscus carinifer Wakefield & McCleery, 2005 Cystiscus connectans (May, 1911) Cystiscus cooverti Boyer, 2003 Cystiscus cratericula (Tate & May, 1900) Cystiscus cymbalum (Tate, 1878) Cystiscus cystiscus (Redfield, 1870) Cystiscus deeae Wakefield & McCleery, 2006 Cystiscus deltoides Boyer, 2003 Cystiscus flindersi (Pritchard & Gatliff, 1899) Cystiscus freycineti (May, 1915) Cystiscus garretti Wakefield & McCleery, 2006 Cystiscus gorii Boyer, 2018 Cystiscus goubini (Bavay, 1922) Cystiscus halli (Pritchard & Gatliff, 1899) Cystiscus havannensis Wakefield & McCleery, 2006 Cystiscus hernandezi Boyer, 2018 Cystiscus incertus (May, 1920) Cystiscus indiscretus (May, 1911) Cystiscus iota (Hedley, 1899) Cystiscus jucundus (W. Turton, 1932) Cystiscus mainardii Cossignani, 2009 Cystiscus maloloensis Wakefield & McCleery, 2006 Cystiscus manceli (Jousseaume, 1875) Cystiscus marshalli Boyer, 2003 Cystiscus maskelynensis Wakefield & McCleery, 2006 Cystiscus matoensis Wakefield & McCleery, 2006 Cystiscus melwardi (Laseron, 1957) Cystiscus microgonia (Dall, 1927) Cystiscus minor Boyer, 2003 Cystiscus minusculus Lussi & G. Smith, 1998 Cystiscus minutissimus (Tenison Woods, 1876) Cystiscus montrouzieri (Bavay, 1922) Cystiscus mosaica Wakefield & McCleery, 2005 Cystiscus nebulosa Wakefield & McCleery, 2005 Cystiscus obesulus (May, 1920) Cystiscus pardus Boyer, 2003 Cystiscus peelae Lussi & G. Smith, 1998 Cystiscus politus (Carpenter, 1857) Cystiscus problematicus (Gatliff & Gabriel, 1916) Cystiscus pseudoaurantius Boyer, 2003 Cystiscus pseustes (E. A. Smith, 1904) Cystiscus punctatus Boyer, 2003 Cystiscus pusillus Wakefield & McCleery, 2006 Cystiscus rendai Boyer, 2018 Cystiscus robini Boyer, 2018 † Cystiscus rotunda (May, 1922) May, W.L. (1922) New species of fossil shells from Table Cape. Papers and Proceedings of the Royal Society of Tasmania, 1921, 9–12, pl. 4. Cystiscus sandwicensis (Pease, 1860) Cystiscus subauriculatus (May, 1915) Cystiscus thouinensis (May, 1915) Cystiscus tomlinianus (May, 1918) Cystiscus triangularis Cossignani, 2008 Cystiscus tricinctus Boyer, 2003 Cystiscus truncatus (Dall, 1927) Cystiscus vavauensis Wakefield & McCleery, 2006 Cystiscus viaderi Boyer, 2004 Cystiscus vidae (Dell, 1956) Cystiscus viridis Boyer, 2003 Cystiscus vitiensis Wakefield & McCleery, 2006 Cystiscus wakefieldi T. Cossignani, 2001 Cystiscus yasawaensis Wakefield & McCleery, 2006
References
2005. Classification and Nomenclator of Gastropod Families. Malacologia 47(1-2):1-397. Laseron, C. F. (1957). A new classification of the Australian Marginellidae (Mollusca), with a review of species from the Solanderian and Dampierian zoogeographical provinces. Australian Journal of Marine and Freshwater Research. 8(3): 274-311
External links
Stimpson W. 1865. On certain genera and families of zoophagous gasteropods. American Journal of Conchology, 1: 55-64, pl. 8-9 Coovert G.A. & Coovert H.K. (1995) Revision of the supraspecific classification of marginelliform gastropods. The Nautilus 109(2-3): 43-110