For example, the lack of mouthparts and antennule
structure and function in non-feeding adults are shared with members of the cyclopoid family Thaumatopsyllidae.
Halicyclops hurlberti belongs to the group of species "B" of Halicyclops with a 3443 spine formula but Rocha (1991) recognized a subgroup of species sharing the following characteristics: 1) caudal setae bearing only heteronomously distributed setules, 2) fourth segment of female antennule
less than twice as long as wide, 3) inner spine of the second basipodite of P1 reaching at least midlength of P1ENP3.
use and agonistic success in the crayfish Orconectes rusticus (Girard, 1852) (Decapoda, Cambaridae)," Crustaceana, vol.
dubia par certains elements lies a la longueur de l'antennule
par rapport a la longueur corporelle, mais surtout par la forme et la taille relative du double somite genital et d'autres segments de l'urosomite.
: Elongated, narrowing distally; end reaching tip of rostrum with aesthetascs surpassing the length of it.
These accumulated chemical compounds might cue the shrimp antennule
flicking, affecting their aesthetascs sensorial capability (Koehl 2006, 2011) and thus the detection of food attractants (de la Haye et al.
proximal article more than 3x as long as wide, article 2 not longer than article 3.
In the western Atlantic Ocean, Perez-Farfante (1969, 1970, 1971a) described diagnostic characters of the genus Farfantepenaeus that allowed identification of individuals in the range of 8-20 mm CL (carapace length) on the basis of the following morphological features: 1) changes in the structure of the petasma and thelycum; 2) absence or presence of distomarginal spines in the ventral costa of the petasma; 3) the ratio between the keel height and the sulcus width of the sixth abdominal somite; 4) the shape and position of the rostrum with respect to the segments and flagellum of the antennule
; and 5) the ratio between rostrum length (RL) and carapace length (RL/CL).
Morphometrics.--Eight characters (body length, body width, eye diameter, rostrum width, length of flagellum on antennule
, length of flagellum on antenna, length of last peduncular article on antenna, length of uropodal exopod) were measured on an approximately equal number of males and females.
This introduces the question of whether structural diversity of the cypris antennule
is correlated with the diversity of habitats and substrata used in settlement by cirripede species.