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Pyramidellidae
Anisocyclidae
Murchisonellidae
Cimidae
Architectonicidae
Orbitestellidae
Omalogyridae
Xylodisculidae
Rissoellidae
  

Lower Heterobranch Addendum

Some authors group the "lower Heterobranchia", Opisthobranchia and Pulmonata within the clade Heterobranchia. The details of the relationships appear to still be in flux. So, we've decided to include an addendum to the site covering families currently placed in the lower Heterobranchia. This is a heterogeneous group that share some features with the more basal opisthobranchs dealt with elsewhere on the site (the families Ringiculidae, Acteonidae, Bullinidae and Aplustridae are sometimes placed in the lower Heterobranchia rather than in the Opisthobranchia). Lower heterobranch families include the Anisocyclidae, Cimidae, Orbitestellidae, Tjaernoeiidae, Xylodisculidae, Architectonicidae, Glacidorbidae, Mathildidae, Omalogyridae, Pyramidellidae, Amathinidae, Murchisonellidae,  Rissoellidae, Valvatidae, Cornirostridae and Hyalogyrinidae (with some variation depending on source). At least the Pyramidellidae, Anisocyclidae, Murchisonellidae, Cimidae, Architectonicidae, Orbitestellidae, Omalogyridae, Xylodisculidae and Rissoellidae are known from Hawaii.

Unlike for 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. Therefore, we can't guarantee that it includes the latest names and it may not be as comprehensive as the opisthobranch section.

Pyramidellidae
The family Pyramidellidae includes mostly small, elongate snails that live primarily as ectoparasites, usually of other mollusks and annelids. However, a few of the larger ones are free living. They lack a radula, using an elongate proboscis to pierce the skin of their host or prey. They are hermaphroditic. Around 46 species are known from Hawaii in the genera Chrysallida, Cingulina, Cossmannica, Evaletta, Evalia, Evalina, Herviera, Iolaea, Lancea, Miralda, Monotygma, Nesiodostomia, Odostomia, Ondina, Oscilla, Otopleura, Pyramidella, Syrnola and Turbonilla.

Information on this family was initially derived from Pilsbry (1917-1921), Kay (1979), Severns (2011), on-line sources and our own material. Then, it was revised following input from Dr. John van Aartsen (revisions are still ongoing and the identifications of some of the species are tentative).

Chrysallida cossmanii

Cingulina sp #1

Cossmannica japonica

Cossmannica sp. #2





Evalea stearnsiella

Evaletta lacteola

Evalina eclecta

Evalina waikikiensis





Herviera gliriella

Herviera sp. #2

Iolaea sp. #1

Lancea peasei





Miralda paulbartschi

Miralda scopulorum

Monotygma(?) sp. #1

Nesiodostomia montforti





Nesiodostomia quarta

Nesiodostomia quinta

Nesiodostomia sp. #1

Nesiodostomia sp. #2





Nesiodostomia sp. #3

Nesiodostomia(?) sp. #4

Nesiodostomia sp. #7

Odostomella chorea





Odostomella rosa

Odostomia cf. chariclea

Odostomia cf. gulicki

Odostomia cf. oxia





Odostomia rosacea

Odostomia sp. #4

Ondina sp. #1

Oscilla indica





Otopleura mitralis

Pyramidella dolabrata

Pyramidella insularum

Pyramidella sulcata





Syrnola aciculata

Syrnola cf. subcinctella

Syrnola cf. teretiuscula

Turbonilla kahoolawensis





Turbonilla thaanumi

un. sp. #5

un. sp. #8

un. sp. #9





un. sp. #18

un. sp. #19




Anisocyclidae
The Anisocyclidae are minute, white, elongate snails that resemble Pyramidellids. There are perhaps two species known from Hawaii in the genus Anisocycla.

Information on this family was initially derived from Kay (1979),  Severns (2011), on-line sources and our own material. Then, it was revised following input from Dr. John van Aartsen.


Anisocycla hawaiiensis

Anisocycla sp. #1

 

Murchisonellidae
The Murchisonellidae are minute, white, elongate snails that resemble Pyramidellids. There is one species known from Hawaii in the genus Murchisonella.

Information on this family was initially derived from Kay (1979),  Severns (2011), on-line sources and our own material. Then, it was revised following input from Dr. John van Aartsen.



Murchisonella columna


 

Cimidae
The Cimidae are minute, white, elongate snails that resemble pyramidellids. There are at least four species known from Hawaii, probably in the genera Cima and Graphis.

Information on this family was initially derived from Severns (2011), on-line sources and our own material. Then, it was revised following input from Dr. John van Aartsen.

Cima(?) sp. #1

Graphis(?) sp. #1

Graphis sp. #2

Graphis sp. #3
 

Architectonicidae
The Architectonicidae (commonly referred to as sundials) include top-shaped or helical snails, often with a deep umbilicus. They resemble the pyramidellids in having a hyperstrophic protoconch (coiled to the left rather than the right). Some species have terraced, horn-like operculums. Most feed on zooanthineareans although the genera Architectonica and Philippia feed on corals as adults. The sexes are separate. At least 14 species are known from Hawaii in the genera Architectonica, Granosolarium, Heliacus, Pseudomalaxis, Psilaxis and Spirolaxis.

The species Torina solcifera Pease, 1869 appears to be unidentifiable with modern material. (Kay, 1979)

Architectonica gualtierii
no photo
available
Architectonica nomotoi

Architectonica perspectiva
no photo
available
Architectonica trochlearis




no photo
available
Granosolarium excavatum

Heliacus areola

Heliacus implexus

Heliacus mighelsi





Heliacus sterkii

Heliacus trochoides

Psilaxis oxytropis

Psilaxis radiatus




no photo
available
Spirolaxis exornatus

Spirolaxis rotulacatharinae


 

Orbitestellidae
The Orbitestellidae are minute, white, helical snails with a broad umbilicus. There are at least three species known from Hawaii in the genera Boschitestella and Orbitestella.

Boschitestella cf. eloiseae

Orbitestella cf. bermudezi

Orbitestella regina
 

Omalogyridae
The Omalogyriridae are minute, brown, planispiral snails. At least two species are known from Hawaii in the genus Omalogyra.


Omalogyra japonica

Omalogyra sp. #1

 

Xylodisculidae
The Xylodisculidae are minute, smooth, helical snails with a broad umbilicus. At lease one species is known from Hawaii in the genus Xylodiscula.


Xylodiscula
sp. #1

 

Rissoellidae
The Rissoellidae are minute, conical snails with transparent shells. They have both cephalic tentacles and elongate oral lobes. They are hermaphroditic. At lease three species are known from Hawaii in the genus Rissoella.

Rissoella cf. confusa

Rissoella longispira

Rissoella sp. #1
 
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