Omphalorissa purchasi is a species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of small land snail

Land snail

A land snail is any of the many species of snail that live on land, as opposed to those that live in salt water and fresh water. Land snails are terrestrial gastropod mollusks that have shells, It is not always an easy matter to say which species are terrestrial, because some are more or less...

, a terrestrial

Terrestrial animal

Terrestrial animals are animals that live predominantly or entirely on land , as compared with aquatic animals, which live predominantly or entirely in the water , or amphibians, which rely on a combination of aquatic and terrestrial habitats...

 gastropod mollusc in the family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Hydrocenidae

Hydrocenidae

Hydrocenidae is a poorly-known taxonomic family of minute land snails or cave snails with an operculum, terrestrial gastropod mollusks or micromollusks in the clade Cycloneritimorpha....

.

The type specimen is stored in the Imperial Natural History Museum

Imperial Natural History Museum

The Imperial Natural History Museum or Imperial Royal Natural History Court Museum of Austria-Hungary was created by Emperor Franz Joseph I during an extensive reorganization of the museum collections, from 1851–1876, and opened to the public on August 10, 1889.Located in Vienna, the Museum was...

, Vienna.

Description

The shell

Gastropod shell

The gastropod shell is a shell which is part of the body of a gastropod or snail, one kind of mollusc. The gastropod shell is an external skeleton or exoskeleton, which serves not only for muscle attachment, but also for protection from predators and from mechanical damage...

 is minute, globosely conical, translucid, imperforate. The sculpture

Sculpture (mollusc)

The sculpture of a mollusc shell is the three-dimensional ornamentation on the outer surface, as distinct from the basic shape of the shell itself or colouration. Sculpture may be concave as well as convex. Sometimes it has microscopic detail. Sculpture refers to the calcareous outer layer, not the...

 consists of very fine growth-striae only. The colour is horny-fuscous. The epidermis thin, shining. The spire

Spire (mollusc)

A spire is a descriptive term for part of the coiled shell of mollusks. The word is a convenient aid in describing shells, but it does not refer to a very precise part of shell anatomy: the spire consists of all of the whorls except for the body whorl...

 is conical, rather obtuse. The protoconch

Protoconch

A protoconch is an embryonic or larval shell of some classes of molluscs, e.g., the initial chamber of an ammonite or the larval shell of a gastropod...

 is minute, strongly convex, smooth. The shell has 4-5 convex whorls

Whorl (mollusc)

A whorl is a single, complete 360° revolution or turn in the spiral growth of a mollusc shell. A spiral configuration of the shell is found in of numerous gastropods, but it is also found in shelled cephalopods including Nautilus, Spirula and the large extinct subclass of cephalopods known as the...

. The last whorl is slightly exceeding one-third of the height of the shell. The base is convex. The suture is impressed. The aperture

Aperture (mollusc)

The aperture is an opening in certain kinds of mollusc shells: it is the main opening of the shell, where part of the body of the animal emerges for locomotion, feeding, etc....

 is a little oblique, subcircular. The peristome is simple, straight. The columella is slightly concave, white. The inner lip is spreading over the umbilicus, sealing it up more or less completely. The callus on the penultimate whorl unites the margins, and is conspicuous.

The width of the shell is 1 mm. The height of the shell is 2 mm.

The has been radula is described by Suter.

Distribution

Omphalorissa purchasi is found on the New Zealand.

• North Island: Bay of Islands
  Bay of Islands
  The Bay of Islands is an area in the Northland Region of the North Island of New Zealand. Located 60 km north-west of Whangarei, it is close to the northern tip of the country....
  
   (Purchas, Hochstetter); Waro
  WARO
  WARO is a commercial radio station located in Fort Myers, Florida, broadcasting to the southwest Florida area on 94.5 FM. WARO airs a classic rock music format branded as "94.5 The Arrow".-External links:*...
  
  ; Whangarei
  Whangarei
  Whangarei, pronounced , is the northernmost city in New Zealand and the regional capital of Northland Region. Although commonly classified as a city, it is officially part of the Whangarei District, administered by the Whangarei District Council a local body created in 1989 to administer both the...
  
  ; vicinity of Auckland
  Auckland
  The Auckland metropolitan area , in the North Island of New Zealand, is the largest and most populous urban area in the country with residents, percent of the country's population. Auckland also has the largest Polynesian population of any city in the world...
  
  ; Wairangi, Waikato Hunua Range; Mount Pirongia
  Mount Pirongia
  Mount Pirongia is an extinct volcano located in the Waikato region of New Zealand's North Island. It rises to 959 metres and is the highest peak in the Waikato region. It was active in the late Pliocene and early Pleistocene times...
  
  ; Forty-mile Bush.
• South Island: Kenepuru Sound
  Kenepuru Sound
  Kenepuru Sound is one of the larger of the Marlborough Sounds in the South Island of New Zealand. The drowned valley is an arm of Pelorus Sound, it runs for 25 kilometres from the northeast to southwest, joining Pelorus Sound a quarter of the way down the latter's path to the Cook Strait.Queen...
  
  ; Nelson; Wairoa Gorge; Greymouth; Riccarton Bush, near Christchurch.

Habitat

It is found in native bush in very moist situations, near creeks or swamps, under stones, rotten wood, etc.

Further reading

• Powell A. W. B.
  Arthur William Baden Powell
  Dr Arthur William Baden Powell CBE was a New Zealand malacologist, naturalist and palaeontologist, a major influence in the study and classification of New Zealand molluscs through much of the twentieth century. He was known to his friends and family by his third name, "Baden".Powell was born at...
  
  , New Zealand Mollusca, William Collins Publishers Ltd, Auckland, New Zealand 1979 ISBN 0-00-216906-1