Strobilops - Pinecone Snails (Family Strobilopsidae)

a Pinecone Snail

Pinecone snails are very distinctive in shape – domed with a ribbed edge (due to coarse transverse striae) giving it a “pinecone” appearance. The lip is reflected. They are small (less than ~3 mm) with a mostly open umbilicus and lamella (long ridge-like “teeth”) on the body whorl moving into the aperture.

Three primary species have been found scattered in the state: Strobilops aeneus (Bronze Pinecone Snail), Strobilops affinis (Eightfold Pinecone Snail) and Strobilops labyrinthicus (Maze Pinecone Snail). A fourth species, Strobilops hubbardi (Flattened Pinecone), has been collected and identified a few times in the southern end of the state by authorities, but is way out of its range. 

Habitat: woodlands, among leaf litter and woody debris; check crevices.

Status: not known.

The key below does not include the Flattened Pinecone.

a Pinecone Snail with periphery labeled

The arrow points to the periphery of the body whorls - it may be more or less angular. 

a Pinecone Snail with lamellae labeled

1st and 2nd lamellae on body whorl.

Identification modified from Burch (1962) and Dourson (2015) – check Dourson (2015) for better descriptions and images.

1a. spire less elevated, its sides only slightly convex, periphery of body whorl angular – Strobilops aeneus
1b. spire more elevated, periphery of last whorl round or subangular – go to 2

​2a. shell small, 2.5 mm or less; lower shell profile, less angular periphery – Strobilops labyrinthica
2b. shell larger, 2.7 mm or more, higher shell profile, more angular periphery – Strobilops affinis

Identification modified from Oesch et al. (2013) - check that source for better descriptions and images.

1a. Basal lamellae, as seen through the base of the shell, nearly equal in length, arranged in oblique, axial series, with some lamellae above the periphery; tallest of the species occurring in Missouri, shape more conic than S. labyrinthicus - S. affinis
1b. Basal lamellae unequal in length - go to 2

2a. Shell short conic shaped, with periphery somewhat angulate; basal lamellae short, lamella 3 sometimes missing; lamellae not occurring above periphery; color dark brown with a reddish golden luster - S. aeneus
2b. Shell beehive shaped, with periphery rounded; basal lamellae longer, with some lamellae often located above the periphery - S. labyrinthicus

see image here

Bronze Pinecone Snail

Strobilops aeneus Pilsbry, 1926

see image  here

Eightfold Pinecone Snail

Strobilops affinis Pilsbry, 1893

no information found

Flattened Pinecone

Strobilops hubbardi  A.D. Brown, 1861

Maze Pinecone Snail

Strobilops labyrinthicus (Say, 1817)