Cavolinia inflexa (Lesueur, 1813) forma imitans (Pfeffer, 1880b)
This is a large shelled thecosomatous pteropod, 0.8 cm long, living in the upper water layers. It has a flat dorsal and ventral side. The caudal spine is long and straight. The lateral spines are well developed at the middle of the shell. Shell sculpture consists of faint growth lines (Cavolinia i. imitans line drawing). Micro-zooplankton and phytoplankton are its food and it is a mucus feeder. It lives in mainly in the Atlantic and Indian Oceans and Mediterranean Sea.
The shell is transparent. The caudal portion of the shell under the lateral spines is smaller than in the form inflexa (Cavolinia i. imitans), and this part is more strongly curved dorsally. The sharply pointed upper aperture lip is rather large. Most characteristic is the incision separating the upper lip. The lateral spines, more developed than in the forma inflexa, are not bent as far caudally as in the forma labiata. Otherwise the shell resembles inflexa. Besides the lateral spines this forma differs from labiata by the relatively larger caudal shell portion.
The shell measures up to 8 mm in length.
A special description of this forma is not available, but see Cavolinia i. forma inflexa. for the description of juveniles.
This species is a protandric hermaphrodite.
This species is phytophagous and epipelagic.
Because of the problems of synonymy few reliable data are available on distribution and the Cavolinia i. imitans map is only a first attempt of mapping, see also the remarks made with the forma inflexa.
Hyalea imitans Pfeffer, 1880: 90, fig. 9a
Lectotype: HMNH (alcohol collection): HMNH 10 spec., 14 spec. (alcohol collection).
Type locality: Atlantic Ocean and Zanzibar, Coll.: Erikson, Schm?,