Diastylidae
Encyclopedia
Diastylidae is one of the eight most commonly recognised families of crustaceans of the order Cumacea
. They are marine creatures especially common around the 30th parallel north
.
Diastylidae have a medium to large, free telson
, that has not fused with the last pleon segment. The telson usually bears two terminal setae.
Males have generally two pairs of pleopods, though in rare cases they may be rather small or even entirely absent. The flagellum of the second antenna reaches past the pereon.
In females the second antenna is much smaller than the first antenna. In males the third maxilliped and the first four pereiopods almost always have exopods (outer branches). In females they may, in rare cases, be absent from all but the third maxillipeds, and the two first pereiopods.
The interior branch of the uropods are generally made up of two or three segments, but in some rare case may have just one. Members of this family frequently show clear sexual dimorphism
.
Cumacea
Cumacea is an order of small marine crustaceans, occasionally called hooded shrimp. Their unique appearance and uniform body plan makes them easy to distinguish from other crustaceans.-Anatomy:...
. They are marine creatures especially common around the 30th parallel north
30th parallel north
The 30th parallel north is a circle of latitude that is 30 degrees north of the Earth's equatorial plane. It stands one-third of the way between the equator and the North Pole and crosses Africa, Asia, the Pacific Ocean, North America and the Atlantic Ocean....
.
Anatomy
Telson
The telson is the last division of the body of a crustacean. It is not considered a true segment because it does not arise in the embryo from teloblast areas as do real segments. It never carries any appendages, but a forked "tail" called the caudal furca is often present. Together with the...
, that has not fused with the last pleon segment. The telson usually bears two terminal setae.
Males have generally two pairs of pleopods, though in rare cases they may be rather small or even entirely absent. The flagellum of the second antenna reaches past the pereon.
In females the second antenna is much smaller than the first antenna. In males the third maxilliped and the first four pereiopods almost always have exopods (outer branches). In females they may, in rare cases, be absent from all but the third maxillipeds, and the two first pereiopods.
The interior branch of the uropods are generally made up of two or three segments, but in some rare case may have just one. Members of this family frequently show clear sexual dimorphism
Sexual dimorphism
Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...
.
Genera
There are around 285 species, in 24 genera:- Anchicolurus Stebbing, 1912
- Anchistylis Hole, 1945
- Atlantistylis Reyss, 1975
- Brachydiastylis Stebbing, 1912
- Colurostylis Calman, 1911
- Cuma Milne-Edwards, 1828
- DiastylisDiastylisDiastylis is a genus of crustaceans which belong to the family Diastylidae. It includes the following species:*Diastylis abboti Gladfelter, 1975*Diastylis abbreviata G. O...
Say, 1818 - Diastyloides G. O. Sars, 1900
- Diastylopsis Smith, 1880
- Dic Stebbing, 1910
- Dimorphostylis Zimmer, 1921
- Divacuma
- Ekleptostylis Stebbing, 1912
- Ektonodiastylis Gerken, Watling & Klitgaard, 2000
- Geyserius
- Holostylis Stebbing, 1912
- Leptostylis G. O. Sars, 1869
- Leptostyloides
- Makrokylindrus Stebbing, 1912
- Oxyurostylis Calman, 1912
- Pachystylis Hansen, 1895
- Paradiastylis Calman, 1904
- Paraleptostylis Vassilenko, 1990
- Vemakylindrus Bacescu, 1961