An email exchange providing information about L. nebulosa and L. angulifera:

2/17/14 After collecting some questionable specimens from Dauphin, Alabama, Steve Rosenthal wrote in personal correspondence to David Reid, Harry Lee, Marlo, and others:

"I looked closely at the 13mm specimen from Dauphin Alabama last week, compared it against my smallest L. nebulosa (17mm) and the excellent pictorial treatment on Marlo's website Lets Talk Seashells for nebulosa- and his nebulosa vs angulifera slides. Although it has some traits of both species, I am fairly sure mine best matches up to the immature nebulosa pictured on Marlos site, eg some of Andy Borgia's small ones from Fl Keys at 8mm on up look very similar. The pattern and columellar ridge are fairly close, though my specimen appears semi adult and not fully developed, but the ridge still reaches fairly close to the top of the aperture.

I wonder if the record you cited for Grand Isle Louisiana (which is just a bit south of Dauphin Is Alabama) and the L angulifera cited on Doug Shelton's Alabama faunal list might in fact be misidentified specimens of nebulosa. Although all the references I checked (The Texas Encyclopedia, Abbott 1974, and Jean Andrews books) include Texas in the range of angulifera they don't give any specifics. I don't know if angulifera HAS to have mangroves, but in TX I think the mangroves don't start until right near the border with Mexico (S. Padre Island), which is at least 200 miles south of Alabama and Louisiana, and I am pretty sure there aren't any mangroves in Alabama or Lousiana. Marlo's website does give records for nebulosa that include the Florida panhandle (same distance from Equator as AL and LA )....so I wonder if angulifera really does occur that far north. Malacolog database didn't seem to cite "Alabama" or "Lousiana" for either species, not that that means anything yay or nay.

Have any of you seen angulifera that far north? or know more about the mangrove distribution and related habitat needs of angulifera?"

2/17 Marlo wrote:

"No Littoraria on the Louisiana checklist http://www.jaxshells.org/efg1030.htm

Doug has it on his Alabama list http://fly.hiwaay.net/~dwills/marine/alamarsp.html#gast

Harry has it on the Florida panhandle list http://www.jaxshells.org/nwfla.htm (my basis)

I have found living L. angulifora on seawalls, concrete bridge pillars, rocks, and wood pilings, and as far north as St. Augustine."

2/17 David Reid [Reid, David. 2009. The genus Echinolittorina habe, 1956 (Gastropoda: Littorinidae) in the western Atlantic ocean. Zootaxa 2184: 1-103.] contributed:

"Littoraria nebulosa and L angulifera can be tricky to separate. The best shell characters are the wide columella and fewer grooves on the last whorl of nebulosa. Here are the diagnoses from my 2009 key to W Atlantic littorinidae (in paper on Echinolittorina):

To 24 mm; 30­45 grooves on last whorl; cream with or without brown lines and dashes; columella wide, flat, white to lilac and stained brown; penis bifurcate, small filament (Reid 1986: fig. 4f). Gulf of Mexico, Florida, Caribbean, to French Guyana. Driftwood, mangroves, sheltered rocks ŠŠ Littoraria nebulosa (Lamarck, 1822) (Bequaert 1943: pl. 4, figs 1­4)

To 40 mm; 48­75 grooves on last whorl; thin-shelled; colour polymorphic; columella narrow, excavated, brown to purple; penis bifurcate, large filament (Reid 1986: fig. 4o); ovoviviparous (embryos in mantle cavity). Bermuda, Florida, Gulf of Mexico, Bahamas, Caribbean, to Brazil. Mangroves, sheltered rocks ŠŠ Littoraria angulifera (Lamarck, 1822) (Reid 1986: fig. 99d­f)

(note that shell lengths of these two were incorrect in the original).

My locality records:

L nebulosa
Many records in Texas; E Summerland Key, Florida; Panama City, Florida; Dauphin I., Alabama.

L angulifera
Many records in Florida (Sanibel I.; Sarasota Bay; Tampa Bay; Nassau Co and Levy Co - both from Harry Lee; Chokoloskee I.; Miami; Lemon City; Clearwater Bay; Pinellas Co.; Cape Romano; Lake Worth; Key Marco; Charlotte Harbour); Port Isabelle, Padre I., Texas (ANSP 284775); Grand Isle, Louisiana (MCZ 160776). The ANSP sample was examined by me in 1981, and I expect Paul Callomon at the Academy would check it if asked. I made a note of the MCZ sample at the same time, recording "very young" - it is not clear from my notes whether I saw the sample or just copied a register, so this lot is suspect.

What is certain is that L angulifera does not absolutely require mangroves; adults can live on sheltered rocks and wood pilings, driftwood etc. Back in the 1970s Susan Gallagher studied a population on a sea wall in Florida, and this seemed to be self-sustaining with recruitment of juveniles.

I'd look at images of doubtful shells if you like."

2/18 Harry Lee reported:

"I find L. nebulosa abundantly on the rocks along Bob Sikes Cut at the W end of St. George Is., near Appalachicola, FL, and the Brunners get L. angulifera in Panama City, ~ 50 mi W of there in the FL Panhandle.

I know that the late Jim Keeler collected repeatedly on St. George Is., but he didn't report L. nebulosa from the region (Keeler and Robertson, 1994). It's possible that its presence is intermittent.

[Keeler, J. and J. Robertson], 1994. Shells of the Appalachicola National Marine Estuarine Research Reserve (and adjacent areas). Florida Dept. Environmental Protection, Tallahassee. Pp. [i] + 1-17. Oct. [Reprinted without editing Sept., 2003]"