''Xanthodaphne membranacea'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

sea snail Sea snail is a common name for slow-moving marine gastropod molluscs, usually with visible external shells, such as whelk or abalone. They share the taxonomic class Gastropoda with slugs, which are distinguished from snails primarily by the ...

, a marine

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...

in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Raphitomidae Raphitomidae is a family of small to medium-sized sea snails, marine gastropod mollusks in the superfamily Conoidea.Bouchet P. & Rocroi J.-P. (Ed.) (2005). "Classification and nomenclator of gastropod families". ''Malacologia'' 47(1-2). . 39 ...

Description

The length of the shell attains 22 mm, its diameter 13 mm. (Original description) The shell is broad, short, tumid, and membranaceously thin. It has a short

spire A spire is a tall, slender, pointed structure on top of a roof of a building or tower, especially at the summit of church steeples. A spire may have a square, circular, or polygonal plan, with a roughly conical or pyramidal shape. Spires are ...

of few somewhat tumid

whorl A whorl ( or ) is an individual circle, oval, volution or equivalent in a whorled pattern, which consists of a spiral or multiple concentric objects (including circles, ovals and arcs). Whorls in nature File:Photograph and axial plane floral ...

s, which are parted by a slight horizontal suture. The surface is smooth and feebly spiralled. The colour of the shell is white, under a thin brownish-yellow smooth persistent membranaceous epidermis. The base is long and gradually contracted,. The snout is broad and lop-sided. The sinus lies close up to the suture.

Sculpture Sculpture is the branch of the visual arts that operates in three dimensions. Sculpture is the three-dimensional art work which is physically presented in the dimensions of height, width and depth. It is one of the plastic arts. Durable sc ...

: Longitudinals—there are fine irregular unequal hair-like lines of growth, which are finely puckered below the suture. Spirals—the whole surface is scored by very slight remote impressed lines, and flat feeble threadlets, which are very irregular, and are interrupted at every biggish line of growth. Just below the suture these are a little feebler, broader, and more regular than elsewhere. The colour is white, under a brownish-yellow, smooth, glossy, thin, membranaceous epidermis. It is entirely translucent from the excessive thinness of the shell. The conical spire is short-pointed. The

protoconch A protoconch (meaning first or earliest or original shell) is an embryonic or larval shell which occurs in some classes of molluscs, e.g., the initial chamber of an ammonite or the larval shell of a gastropod. In older texts it is also called ...

is eroded but evidently small. There are five remaining whorls. They are short, broadish, and a little tumid, convex, rounded, not keeled, not at all contracted below. The body whorl is large, tumid, and elongated, being drawn out on the base, which is long and rounded. The aperture is broad, but is somewhat broken. The suture is linear and slight, but distinct in consequence of the junction of the whorls. The aperture is semi-lunar, sharply angulated above and below. The outer

lip The lips are the visible body part at the mouth of many animals, including humans. Lips are soft, movable, and serve as the opening for food intake and in the articulation of sound and speech. Human lips are a tactile sensory organ, and can be ...

is very thin, regularly curved, with a deep wide sinus close up to the suture, whence the front edge of the shell makes a prodigious forward and downward sweep, and then retreats again to the point of the

columella Lucius Junius Moderatus Columella (; Arabic: , 4 – ) was a prominent writer on agriculture in the Roman Empire. His ' in twelve volumes has been completely preserved and forms an important source on Roman agriculture, together with the wo ...

. The inner lip does not seem to have even a glaze on the body. There above, the line is convex, but down the very slightly swollen columella it runs direct but very obliquely to the left. The point of the columella is not truncate, but the sharp edge runs out with a twist, and forms a sharp point at the end of the columella. The broad open

siphonal canal The siphonal canal is an anatomical feature of the shells of certain groups of sea snails within the clade Neogastropoda. Some sea marine gastropods have a soft tubular anterior extension of the mantle called a siphon through which water is ...

in front seems not to have been in the slightest degree emarginate.Watson R.B. (1886). Report on the Scaphopoda and Gasteropoda collected by H.M.S. Challenger during the years 1873–76. Report on the Scientific Results of the Voyage of H.M.S. Challenger during the years 1873–76. Zoology. 15 (part 42): 1–756, pls 1–50 - page 333
/ref>

Distribution

This marine species is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to New Zealand and occurs off

North Island The North Island, also officially named Te Ika-a-Māui, is one of the two main islands of New Zealand, separated from the larger but much less populous South Island by the Cook Strait. The island's area is , making it the world's 14th-largest ...

References

* Powell, A.W.B. 1979 ''New Zealand Mollusca: Marine, Land and Freshwater Shells'', Collins, Auckland * Spencer, H.G., Marshall, B.A. & Willan, R.C. (2009). Checklist of New Zealand living Mollusca. Pp 196–219. in: Gordon, D.P. (ed.) New Zealand inventory of biodiversity. Volume one. Kingdom Animalia: Radiata, Lophotrochozoa, Deuterostomia. Canterbury University Press, Christchurch.

External links

*
Spencer H.G., Willan R.C., Marshall B.A. & Murray T.J. (2011). Checklist of the Recent Mollusca Recorded from the New Zealand Exclusive Economic Zone
{{DEFAULTSORT:Xanthodaphne Membranacea membranacea Gastropods described in 1886 Gastropods of New Zealand