''Gurmatia'' is an extinct small

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of pyramidellid

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

s or

micromollusk A micromollusc is a shelled mollusc which is extremely small, even at full adult size. The word is usually, but not exclusively, applied to marine molluscs, although in addition, numerous species of land snails and freshwater molluscs also ...

s in the family

Pyramidellidae Pyramidellidae, common name the pyram family, or pyramid shells, is a voluminous taxonomic family of mostly small and minute ectoparasitic sea snails, marine heterobranch gastropod molluscs. The great majority of species of pyrams are micromol ...

. The genus is known only from

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

s (

Holocene The Holocene () is the current geologic time scale, geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene to ...

Shell description

The shell in this genus is small, ovate-conic, thin and translucent. 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 heterostrophic and smooth, and it is obliquely immersed in the first adult whorl. The adult shell has a sculpture of spiral cords which are separated by deep grooves. The spiral cords have numerous transverse threads in their intervals. The straight, vertical

aperture In optics, the aperture of an optical system (including a system consisting of a single lens) is the hole or opening that primarily limits light propagated through the system. More specifically, the entrance pupil as the front side image o ...

lacks the fold that most members of

Odostomiinae Odostomiinae, ''Odostomia'' snails and their allies, is a taxonomic subfamily of minute parasitic sea snails. These are marine heterobranch gastropod mollusks, or micromollusks, in the family Pyramidellidae. Taxonomy The subfamily Odostomiinae ...

have. The shell opening (

) is truncate-subovate. Compared to '' Euparthenia'' Thiele, 1929, ''Gurmatia'' lacks a columellar fold and has no axial ribs. Compared to '' Monotygma'' J. E. Gray, 1847 (=''Actaeopyramis'' Fisher, 1885) it is considerably smaller, and is more strongly shouldered. The type species is ''Gurmatia wilkinsi'' Dance & Eames, 1966. This is a small shell. It is ovate-conic in outline, thin and translucent. The protoconch is smooth, heterostrophic and obliquely immersed in the succeeding whorl. The post-nuclear whorls with spiral cords are separated by deep grooves. The spiral cords are with numerous, transverse threads in their intervals. The columella is without folds (teeth) and straight and vertical. The aperture is truncate to subovate and imperforate. Compared to '' Euparthenia'' - ''Gurmatia'' has lacks axial ribs and columellar folds. Compared to '' Actaeopyramis'', it is much smallerand with fewer whorl that are more strongly shouldered. It is less turreted, lacking spiral rows of punctae in the intervals between the spiral cordons. The spiral cordons themselves are relatively stronger. If compared to ''

Leucotina ''Leucotina'' is a genus of small sea snails, marine heterobranch gastropod molluscs or micromolluscs in the family Amathinidae.MolluscaBase eds. (2021). MolluscaBase. Leucotina A. Adams, 1860. Accessed through: World Register of Marine Specie ...

'', it is less ovate and has a higher spire with more shouldered whorls. The last whorl is also less prominently convex. It is lacking the spiral rows of punctae between the spiral cordons, and shows no trace of a columellar fold." The shell of the type species is small and thin, ovate-conic, white to semi-translucid. The protoconch is smooth, consisting of one and half whorls obliquely immersed in the succeeding whorl. Three post-nuclear whorls that are moderately convex and gently shouldered, with a deep linear suture. The spire occupies about 2/3 of the total height of the shell. The sculpture consists of 5-7 rounded, equidistant, spiral cords separated by deep spiral grooves of about equal width. The spiral cords has numerous, regularly spaced, procurrent transverse threads (about 1/2 to 1/3 the width of their intervals) between them. The base of the last whorl has six to seven additional spiral cords which become weaker abapically. The aperture is truncate to subovate. The outer lip is thin and semi-transparent, practically straight and gently procurrent. It is smooth internally. The columella is perpendicular and without folds. It is Imperforate. The measurements of the holotype are: Height 26 mm. Width 1–2 mm, and of the paratype: Height 3–1 mm. Width 1–0 mm. Type locality:. Gurmat Ali, right bank, 56 ft below surface of Alluvium holotype; Recent, Madras, M. D. Crichton leg., one paratype.

Life habits

Little is known about the biology of the members of this genus. As is true of most members of the

sensu lato ''Sensu'' is a Latin word meaning "in the sense of". It is used in a number of fields including biology, geology, linguistics, semiotics, and law. Commonly it refers to how strictly or loosely an expression is used in describing any particular co ...

'', they are most likely

ectoparasite Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted str ...

Species

Species within the genus ''Gurmatia'' include: * † '' Gurmatia wilkinsi'' Dance & Eames, 1966 - type species, deposited at The

Natural History Museum A natural history museum or museum of natural history is a scientific institution with natural history scientific collection, collections that include current and historical records of animals, plants, Fungus, fungi, ecosystems, geology, paleo ...

, London with access number B.M.N.H. 196528. * † '' Gurmatia pulchrior'' (Melvill, 1904)

References

{{Taxonbar, from=Q5620165 Pyramidellidae