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Velutinidae
Eratoidae
Triviidae
Marginellidae
Cystiscidae
  

 
Prosobranch Addendum
 
The prosobranch gastropods aren't closely related to the heterobranchia. So, they're technically outside the scope of this site. Most are readily distinguished from the opisthobranchs. However, a few families are often mistaken for them and we've added this addendum to illustrate the Hawaiian species in some of them

The following information is based primarily on Kay, 1979 and whatever we've been able to pick up on-line. Unlike the opisthobranchs, we haven't kept extensive notes on these families--no running log of finds or detailed records of the source of photographed animals. So, we can't guarantee that it includes the latest names and it may not be as comprehensive as the opisthobranch section.

Velutinidae
Velutinids are prosobranch gastropods of the  family Velutinidae (sometimes referred to as the Lamellariidae). They have an internal shell that is covered by the mantle (which is often elaborately colored or ornamented). They are frequently mistaken for dorid nudibranchs or pleurobranchids but  may be distinguished from both groups by their unrolled cephalic tentacles that emerge from beneath the mantle and have bulbous eye spots at their bases. In contrast, dorids have rhinophores emerging from the top of the mantle and pleurobranchids have rolled rhinophores that emerge from beneath the mantle. They feed on colonial tunicates and are often very cryptic when seen on their hosts. Many velutinids are also highly variable in color and/or texture making identification difficult. There are probably about 13 species known from Hawaii in, perhaps, three genera: Coriocella, Lamellaria and Marseniopsis.

Coriocella nigra

Lamellaria sp. #1

Lamellaria sp. #2

Lamellaria sp. #3





Lamellaria(?) sp. #4

Lamellaria sp. #5

Lamellaria sp. #6

Lamellaria sp. #7





Lamellaria(?) sp. #10

Lamellaria sp. #11

Marseniopsis sp. #1
no photo
available
Marseniopsis sp. #2





un. sp. #7





In addition to the Velutinidae, there are four other families that are included in the superfamily Cypraeoidea: Cypreidae, Ovulidae, Eratoidae and Triviidae. Although they have external shells, they share the characteristic of being able to cover their entire shell with their mantle. The best known are the Cypreidae or cowries. They are extensively covered, elsewhere, so we're not including them at this time. The Hawaiian Ovulidae are generally confined to water deeper than 50 m (in association with Gorgonians) and are unlikely to be seen by recreational divers. However, Hawaiian Eratoidae and Triviidae have seldom been illustrated and are found in shallow water.
 
Eratoidae 
The Eratoidae are small snails with visible apexes when adult. They feed on compound ascidians.. Only one species is known from Hawaii in the genus Eratoena. The family was previously included in the Triviidae.


Eratoena sandwichensis

 
Triviidae
The Triviidae include small cowrie-like species found in both rocky habitats and Halimeda kanaloana beds. Like cowries, they start out as "typically-shaped" snails, then transform into an adult form in which the aperture is restricted to a narrow slit and the apex is obscured. The size at maturity is variable and the number of ribs, depth of the dorsal sulcus and development of the lateral callous vary with age. They feed on compound ascidians. There are at least four species in Hawaii in the genera Cleotrivia, Purpurcapsula and Trivirostra.

Due to uncertainty in the nomenclature, we are adopting the genera used in Severns, 2011 but retaining the combinations used in Kay, 1979 (pending further clarification).

Cleotrivia globosa

Purpurcapsula exigua

Trivirostra edgari

Trivirostra hordacea


The following two families are not closely related to the velutinids. But, due to their transparent shells and small size they are occasionally mistaken for cephelaspideans.

Marginellidae
The family Marginellidae includes small transparent to translucent snails with well-defined columellar folds. There are three species known from Hawaii in the genera Dentimargo, Granulina and Volvarina.

Dentimargo pumilus

Granulina vitrea

Volvarina unilineata
 
Cystiscidae
The family Cystiscidae includes small transparent to translucent snails with well-defined columellar folds. The body of the animal showing through the shell is often strikingly patterned. There are at least four species known from Hawaii including the genera Crithe and Cysticus. Until recently these species were placed in the Marginellidae.

Crithe huna

Crithe sp. #1

Cystiscus sandwicensis

un. sp. #1

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