Gurmatia
Encyclopedia
Gurmatia is an extinct small genus
of pyramidellid
gastropod mollusks or micromollusk
s in the family Pyramidellidae
.
The genus is known only from fossil
s (Holocene
).
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
lacks the fold that most members of Odostomiinae
have. The shell opening (aperture
) 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, 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.
sensu lato, they are most likely ectoparasites.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of pyramidellid
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 or micromolluscs....
gastropod mollusks or micromollusk
Micromollusk
A micromollusk is a descriptive term for a shelled mollusk which is extremely small, even at full adult size. The word is usually, but not exclusively, applied to marine mollusks, although in addition, numerous species of land snails and freshwater mollusks also reach adult size at very small...
s in the family Pyramidellidae
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 or micromolluscs....
.
The genus is known only from fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s (Holocene
Holocene
The Holocene is a geological epoch which began at the end of the Pleistocene and continues to the present. The Holocene is part of the Quaternary period. Its name comes from the Greek words and , meaning "entirely recent"...
).
Shell description
The shell in this genus is small, ovate-conic, thin and translucent. The protoconchProtoconch
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 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
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....
lacks the fold that most members of Odostomiinae
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:...
have. The shell opening (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 truncate-subovate.
Compared to Euparthenia
Euparthenia
Euparthenia is a subgenus of very small sea snails, pyramidellid gastropod mollusks, or micromollusks in the subfamily Turbonillinae.The name Euparthenia is a replacement name for Parthenia Lowe, 1841 not Robineau-Desvoidy, 1830....
Thiele, 1929, Gurmatia lacks a columellar fold and has no axial ribs. Compared to Monotygma
Monotygma
Monotygma is a genus of very small sea snails, pyramidellid gastropod mollusks, or micromollusks. This genus is currently placed in the subfamily Chrysallidinae of the family Odostomiidae. The status of this genus was for a long time confused, but the situation was clarified in a review by van...
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
Euparthenia
Euparthenia is a subgenus of very small sea snails, pyramidellid gastropod mollusks, or micromollusks in the subfamily Turbonillinae.The name Euparthenia is a replacement name for Parthenia Lowe, 1841 not Robineau-Desvoidy, 1830....
- Gurmatia has lacks axial ribs and columellar folds. Compared to Actaeopyramis
Actaeopyramis
Actaeopyramis is a genus of sea snails, marine gastropod mollusks in the family Pyramidellidae, the pyrams and their allies.-Species:The following species were brought into synonymy:...
, 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, 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 PyramidellidaePyramidellidae
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 or micromolluscs....
sensu lato, they are most likely ectoparasites.
Species
Species within the genus Gurmatia include:- † Gurmatia wilkinsi Dance & Eames, 1966 - type species, deposited at The Natural History MuseumNatural History MuseumThe Natural History Museum is one of three large museums on Exhibition Road, South Kensington, London, England . Its main frontage is on Cromwell Road...
, London with access number B.M.N.H. 196528. - † Gurmatia pulchrior (Melvill, 1904)