la. Aperture of shell closed by an operculum (snail must be collected live because the operculum is lost soon after death). Mantle cavity with gill on dorsal surface ------------------------------------------------------------- Subclass PROSOBRANCHIA --- 2.

lb. Aperture non-operculate; mantle cavity modified into a lung ------------------------------------ Subclass PULMONATA --- 59.

2a. Operculum calcareous with two pegs on inner surface (Figs. 1, 2). Aperture relatively large with fine, uneven, serrate denticles along parietal wall (Fig. 3) -------------------------------- NERITIDAE (Olive Nerite) Neritina usnea (Röeding, 1798).

Fig1., 2.

The only freshwater neritid in Florida. Height 15-20 mm; width 14-19 mm. Shell solid, relatively heavy, dark green with numerous, narrow black stripes. Widely distributed in brackish water in the Caribbean and Gulf of Mexico region. invades freshwater zone in lower parts of some rivers. Found in Florida along both coasts. This species generally was listed as Neritina reclivata (Say, 1822) in previous literature. The name is a junior synonym of Neritina usnea.

Fig. 3.

2b. Operculum corneas, without pegs on inner or outer surface. Aperture without serrate denticles on parietal wall ----- 3.

Operculum with concentric growth rings around nucleus (Figs. 4, 5). Shell medium to large (12-75 mm) ---------------------------------------------------------------------------------------------------------------------------------------------- Superfamily VIVIPAROIDEA --- 4.

3b. Operculum spiral, consisting of two or more rapidly increasing whorls (Fig. 6). Shell usually small to medium (2-25 mm)----------------------------------------------------------------------------------------------------------------------------------------------------------14

4a. Umbilicus of shell perforated or broadly open. Spire depressed, much less than height of aperture, occasionally planular (Figs. 7-9). Aperture relatively ample (Figs. 10- 12). In some genera, eggs are deposited above the water in dry clusters on stems, trees, walls, etc. In others they are deposited in the water in gelatinous clusters. Males with penis at anterior right corner of mantle cavity --------------------------------------------------------------------------------- AMPULLARIIDAE --- 5.

4b. Umbilicus of shell closed. Spire usually about equal to or greater than height of aperture (Figs. 17-29). Females with live embryos in brood pouch in mantle; males with right eye stalk modified as a penis. ------------------ VIVIPARIDAE --- 7.

Medium- to large-sized tropical freshwater snails. One species occurs naturally in Florida, and three others have been introduced. The family contains many genera and numerous species in South America, Central America, Mexico, Africa, and Southeast Asia. Frequently the shells of ampulariids and viviparids are very similar. The shell characters given above for separating the families apply only to Florida species. The primary differences between the two families are based on soft anatomy. Ampullariids have been referred to as PILIDAE in earlier editions of this manual. The International Commision on Zoological Nomenclature has ruled that AMPULLARIIDAE is the valid name for this family of snails.

5a. Shell planispiral, adults large, 35-50 mm (Figs. 7-9)---(Goldenhorn Marisa) Marisa cornuaurietus (Linnaeus, 1758).

Introduced from northern South America into South Florida canals, marshes, and ponds. Currently known in Florida from Palm Beach, Broward, Dade, and Monroe counties. The eggs are laid in gelatinous clusters in the water.

5b. Shell oval in shape.------------------------------------------------------------------------------------------------------------- Pomacea --- 6.

6 Genus Pomacea Perry, 1810 ------------------------------------------------------------------------------------------------------------------- 6a.

6a. Whorls of spire pointed and scalariform (steplike with nearly flat shoulders and deep sutures). Apical whorls raised to form a point on top of spire. Adult shells about 40-60 mm high (Fig. 10) ------------------------------------------------------------------------------------------------------------------------------------------------- (Spiketopped Applesnail) Pomacea bridgesi (Reeve, 1856).

A South American species introduced into South Florida in Monroe, Dade, Broward, Palm Beach and Pinellas Counties. Generally the shell is greenish with darker and lighter bands.

6b. Apical whorls pointed and raised, but not scalariform. Shell large, 80-100 mm wide. Suture deeply impressed, forming a channel. Umbilicus wide (Fig. 11). ----------- (Channeled Applesnail) Pomacea canaliculata (Lamark, 1822).

This is another South American species that has been introduced into canals and ditches in southeast Florida (Thompson, 1997).

6c. Whorls of spire strongly arched or rounded. Apical whorls bluntly rounded and not conspicuously elevated. Adult shells about 40 - 70 mm high (Fig. I2) -------------------------------------------- (Florida Applesnail) Pomacea paludosa (Say, 1829).

Widely distributed throughout the Florida peninsula, and occurring sporadically west of the Suwannee River to the Choctawhatchee River. The Florida Applesnail occurs in Cuba. It is found in Georgia in isolated springs along the Flint and Ocmulgee rivers and is introduced in Covington County, Alabama, in a small reservoir artificially heated by industrial wastewater. Otherwise the species is not able to survive the lower winter temperatures that occur along the northern tier of Florida counties and northward. It has been introduced extensively into Pacific islands and southeast Asia, where it is raised for human consumption. The species has existed continuously in the Florida peninsula since the Pliocene. A small, reddish, thick-shelled form with a wider umbilicus, which occurs in Dade and Broward counties, has been named as a distinct species, Pomacea miamiensis (Pilsbry, 1899) (Fig. 13). Its taxonomic status is uncertain.

Medium to large freshwater snails found on all continents except South America. The family attains its greatest diversity in Southeast Asia. Two subfamilies occur in North America. The LIOPLACINAE is endemic and include Campeloma, Lioplax, and Tulotoma. The VIVIPARINAE is widely distributed throughout Europe, Asia and eastern North America. It is represented in North America by Viviparus. Various species of Cipangopaludina also have been introduced from the Orient into North America. One species, C. chinensis malleatus (Reeve, 1863) (Fig. 14), was introduced into a fishpond in St. Petersburg about 1921 and into lakes in Orlando about 1940. The current status of these introductions is not known.

7a. Nucleus of operculum spiral and then surrounded by concentric growth rings (Fig. 5). Outer lip of aperture strongly sinuous in lateral profile (Fig. 15) ------------------------------------------------------------------------------ Lioplax Troschel, 1856 --- 8.

7b. Operculum constructed entirely of concentric rings (Fig. 4). Outer lip of aperture nearly straight in lateral profile (Figs. 16, 17) ----------------------------------------------------------------------------------------------------------------------------------------------------- 9.

A single species consisting of two highly variable subspecies occurs in Florida. Three other species occur farther north.

8a. Shell larger, reaching a maximum diameter of 18 mm. Spiral angulation on whorls sharp and prominent in juveniles, usually becoming convex-rounded or smooth on last whorl in adults. Prominent minor spiral sculpture along periphery. Outer lip strongly sinuous. Newborn young about 4.5 mm in diameter (this can be determined by removing juveniles from brood pouch). Height of shell about 23-26 mm (Figs. 15, 18) --------------------------------------------------------------------------------------------------------------------------------------------------------------------- (Choctaw Lioplax) Lioplax pilsbryi pilsbryi Walker, 1905.

Confined to the Chipola River, and small streams along the west side of the Apalachicola River.

8b. Shell smaller, reaching a maximum diameter of 13 mm. Spiral angulation on last whorl obsolete or bluntly rounded and forming a shallow sulcus below shoulder of last whorl. Minor spiral sculpture weak or absent. Outer lip less sinuous. Newborn young about 3 mm in diameter. Height of shell about 14-16 mm; width, 10-12 mm (Figs. 19-21) -------------------------------------------------------------------------------------- (Choctaw Lioplax) Lioplax pilsbryi choctawhatchensis Vanatta, 1935.

Found in the Escambia, Yellow, Choctawhatchee (Fig. 19), Chattahoochee, Flint, Ochlockonee (Fig. 20), and Suwannee Rivers (Fig. 21) and their tributaries in Florida, Alabama, and Georgia. The populations from the Ochlockonee and Yellow rivers were named as a distinct species (Lioplax talquinensis Vail, 1979b) on the basis that they have a distinct sulcus on the last whorl causing the aperture to be pinched above (Fig. 20). Populations from other rivers lack the sulcus and have a more broadly open aperture (Fig. 19). The examination of large series of specimens from the Choctawhatchee, Yellow, Ochlockonee, and Suwannee rivers and Holmes Creek show that these distinctions are inconsistent.

9a. Shell thick and solid; whorls weakly convex or flattened (Figs. 16, 22-28). Shell unicolor, never banded ----------------------------------------------------------------------------------------------------------------------------------- Campeloma Rafinesque, 1819 ---10.

9b. Shell generally thin but strong; whorls of spire strongly convex with deep suture (Figs. 17, 29-32), shell usually banded in Florida forms. --------------------------------------------------------------------------------------------------Viviparus Montfort, 1810 ---13.

Moderately large, thick-shelled operculate snails. Some species are dioecious with a normal representation of males and females. In others, some or all populations may be parthenogenetic, consisting only of females, or they may have a disproportionately small number of males. In parthenogenetic organisms each population is inbred in the strictest genetic sense, and frequently a population will have minor characteristics that distinguish it from others. There is no consensus in systematic biology about how to treat these forms. The criterion of inbreeding for defining species cannot be applied, and other objective criteria are not yet been established.

10a. Shell obese and ponderous. Spire short and compact, about 0.5-0.7 times height of aperture in mature specimens, proportionally longer in juveniles (Fig. 22) ------------------- (Ovate Campeloma) Campeloma geniculum (Conrad, 1834).

10b. Shell more slender and attenuate; spire more elongate in adults, about 0.7- 1.0 times height of aperture -----------11.

1la. Interior of adult aperture with brownish tinge. Newborn shells brown. Outer lip continuously rounded (Figs. 23, 26) -------------------------------------------------------------------------- (Purple-throated Campeloma) Campeloma floridense Call, 1886.

Height of adult shell about 23-27 mm; width about 15-20 mm. Confined to the St. Johns River system and the upper part of the Santa Fe River in Florida. The brown tinge of the aperture is absent in many specimens.

1lb. Interior of aperture livid white. Newborn shells white. Outer lip partially flattened in adults ----------------------------------12.

12a. Outer lip nearly straight and parallel to axis of shell in adults (Fig. 24, 27) ------------------------------------------------------------------------------------------------------------------------------------------- (Maiden Campeloma) Campeloma parthenum Vail, 1979.

Height of adult shell about 23-27 mm, width about 16-19 mm. Reported from the Ochlockonee River and its tributaries in Florida. Similar specimens are found in the Conecuh and Pea rivers in southern Alabama.

12b. Outer lip straightened just below shoulder; straightened portion lying at an angle to axis of shell (Figs. 16, 25, 28) ----------------------------------------------------------------------------------------- (File Campeloma) Campeloma limum (Anthony, 1860).

Height of adult shell about 25-32 mm; width about 17-19 mm. Populations with these characteristics are found from the upper tributaries of the Escambia, Choctawhatchee, Suwannee, and St. Mary’s river systems in Alabama, Georgia, and northeast Florida, and north along the Atlantic coast to North Carolina and Virginia.

13 Genus Viviparus Montdort, 1810 ---------------------------------------------------------------------------------------------------------- 13a.

Medium- to large-sized, globose, freshwater snails that usually live in silty or mud-bottomed streams, ponds, lakes, and marshes. These snails are more tolerant to pollution and stagnation than are Campeloma and Lioplax, and they thrive in aquatic environments that are too adverse for most other genera. Two species are included in the key. One, V. intertextus, has not been recorded from Florida, but it occurs in immediately adjacent river systems in Alabama and Georgia and may be anticipated in the northern tier of Florida counties. The second species, V. georgianus, is widely distributed and is found in most freshwater habitats in Florida.

13a. Shell ovate in shape, about 1.2-1.5 times as high as wide. Shell relatively thick (Figs. 16, 29). -------------------------------------------------------------------------------------------------------------- (Banded Mysterysnail) Viviparus georgianus (Lea, 1834).

Adult shells about 20-45 mm high and about 18-36 mm wide exist in locally isolated populations and inhabit a wide diversity of aquatic environments. Populations are highly variable in banding patterns and in size of individuals, although each population tends to be uniform in its characteristics. As a consequence, fourteen subspecies names have been proposed for various Florida forms based upon color and shell obesity. Any given population may have individuals with 0-4 spiral bands. No geographic patterns exist that permit recognition of them as subspecies. They are regarded as variations of V. georgianus without taxonomic significance although some populations may differ strikingly from others.

13b. Shell globose with a relatively depressed spire; about 1.0- 1.2 times as high as wide. Suture of whorls more deeply impressed than in previous species. Shell relatively thin. Color uniform olive-green, never banded (Fig. 32) ----------------------------------------------------------------------------------------------------- (Rotund Mysterysnail) Viviparus intertextus (Say, 1829).

Height of adult shell about 20-30 mm; width about 20-25 mm. Distributed from east Texas and throughout the Mississippi River east to the Alabama River with disjunct populations in the Altamaha River system in Georgia and elsewhere into South Carolina. Viviparus intertextus is replaced in this disjunct area by Viviparus georgianus. Viviparus intertextus may occur in west Florida.

14a. Shell elongate-conical; 10-40 mm long in adult specimens; apex of spire usually eroded; shell with 8-12 whorls although eroded specimens may have fewer; shell usually strongly sculptured with spiral and/or vertical ribs and threads (except in Elimia dickinsoni); central tooth of radula without basal or lateral cusps (Fig. 33); males without copulatory structures.---------------------------------------------------------------------------------------------------- Superfamily CERITHIOIDEA ---15.

14b. Shell variable in shape, elongate to globose; usually not more than 5 mm in length; apex of spire seldom eroded (except in Somatogyrus); 4-6 whorls; shell smooth (except in Pyrgophorus and Tryonia); central tooth of radula with basal cusps (Figs. 34, 35) (Pomatiopsis, Fig. 36); males with a copulatory appendage, a penis (Fig. 37), which is important for generic and specific diagnosis. (The penis is normally recurved into the mantle cavity, except during mating.----------------------------------------------------------------------------------------------------------- Superfamily RISSOOIDEA --- 24.

15a. Operculum paleomelanian, with a large sub-centrally located nucleus (Fig. 38). (This character separates only the genera under consideration; genera from other areas of the world do not conform to this distinction.) Females with an egg-laying groove or sinus on right side of foot; eggs deposited on substrate. -------------------- PLEUROCERIDAE --- 18.

15b. Operculum neomelanian, with a small, rapidly expanding nucleus located near the basal margin (Fig. 39). Primarily parthenogenetic; females viviparous with young snails in a brood pouch in nape.---------------------------- THIARIDAE ---16.

Thiarids are found in tropical and subtropical regions of the world. Most inhabit fresh water, but some also occur in brackish water. The greatest diversity of genera and species is in the Indo-Australian region. Endemic New World genera occur in Cuba, Jamaica, and northern South America. Three species in Florida were introduced from Southeast Asia. Two, Melanoides tuberculata and Tarebia granifera, are medically important because they can serve as first intermediate host for the human lung fluke, Paragonimus westermani. Thiarids are ecologically significant because they tend to replace native snails where they are introduced and because of their abundance. In 1976 in the St. Johns River 1 found Melanoides tuberculatus with population densities of 10,000/sq. m.

16a. Shell sculptured with prominent nodes overlapping suture and forming crenulations. Base of last whorl with prominent spiral ridges. Shell unicolor brown, never mottled with reddish spots. Shell about 0.38-0.41 times as wide as high and about 20-27 mm long. Sides of spire concave in outline (Fig. 40). ------------------------------------------------------------------------------------------------------------------------------------------------------- (Quilted Melania) Tarebia granifera (Lamarck, 1822).

Abundant in some springs and small streams in Florida. Some authors identify this species as Tarebia lateritia (Lea, 1850). Considerable variation in obesity and sculpture rugosity exists between different populations, and there is disagreement as to how many species occur in Florida.

16b. Shell sculptured with fine spiral striations, and in some cases curved axial ribs. Suture simple, not crenulated. Shell usually marked with red or rust-colored spots, flames, or bands (most apparent on juvenile specimens). Shell more slender, about 0.30-0.35 times as wide as high. Sides of spire straight-sided in outline.---------------------------------------------------------------------------------------------------------------------------------------------------------------------- Melanoides Oliver, 1904 ---17.

17a. Shell sculptured with vertical, weakly curved ribs and much finer spiral striations. Prominent vertical ribs on middle and upper whorls. Base of shell with dark red spiral band. Shell light brown and frequently mottled with rust-colored spots that may form a spiral row below the suture. Attains a length of about 30-36 mm (Figs. 41-43). ---------------------------------------------------------------------------------------------------------------- (Red-rimmed Melania) Melanoides tuberculata (Müller, 1774).

Widely introduced throughout Florida. Most commonly found in rivers, streams, canals, and springs.

17b. Shell sculptured with fine spiral threads. Fine vertical ribs present on uppermost whorls. Base of shell usually without spiral band. Shell olive-green with vertical reddish flames and spots. Attains a length of 30-40 mm (Fig. 44). --------------------------------------------------------------------------------------------------------------- (Fawn Melania) Melanoides turricula (Lea, 1862).

A Philippine snail that has been introduced into springs and spring-fed streams in Florida and Texas. Melanoides tuberculata and Melanoides turricula may be ecological variations of a single species. In Florida, the two types are ecologically segregated; Melanoides tuberculata is generally found in quieter, eutrophic, turbid habitats; Melanoides turricula is found in cleaner oligotrophic springs and streams.

18a. Last whorl of adult shell smooth or with growth striations, but not with ribs and spiral chords. --------------------------19.

18b. Shell with prominent ribs and spiral chords on all whorls.--------------------------------------------------------------------------- 20.

19a. Earlier whorls of adult shell with vertical ribs and spiral chords. Sides of spire straight in lateral profile. Last few whorls in large adults scalariform. Embryonic shell with fine vertical ribs and a heavy spiral chord on periphery and two basal spiral chords (Fig. 45). Adult large, about 23-27 mm long (Figs. 49, 50). ------------------------------------------------------------------------------------------------------------------------------------------ (Stately Elimia) Elimia dickinsoni (Clench & Turner, 1956).

Confined to small creeks in the upper part of the Choctawhatchee River. Named for Joshua C. Dickinson, Jr. (1916-), former director of the Florida Museum of Natural History.

19b. Earlier whorls of adult shell with heavy vertical ribs crossed by knobby folds or a strong spiral chord; sides of spire straight or weakly convex in lateral profile; embryonic shell with a single spiral chord on periphery and heavy vertical ribs, but without basal spiral chord (Fig. 46). -------------------------------------------------------------------------------------------------------- 20.

20a. Spire of adults with heavy vertical ribs; unicolor dark brown; usually less than 18 mm long (Figs. 51, 52). -------------------------------------------------------------------------------------------------------------- (Graphite Elimia) Elimia doolyensis (Lea, 1962).

Distributed from the lower part of the Apalachicola River system in Georgia and Florida west to the Chipola River system in Florida and Alabama. This snail primarily inhabits smaller streams and tributaries and also occurs in subterranean aquifers in Washington County, Florida.

In earlier editions of the manual this snail was listed as Elimia curvicostata. The name was based on Melania curvicoststa Reeve, 1861,but that name is preoccupied by Melania curvicostata Melleville, 1843, a European Miocene fossil. The next name to be refered to this species in the literature, Melania densicostata Reeve, 1860, is not identifiable with certainty. The only available name that can be applied to this species is Goniobasis doolyensis Lea, 1862.

21a. Shell brightly banded and with large, wide and wavey vertical folds; robust, usually 21-25 mm long (Fig. 53). --------------------------------------------------------------------------- (Choctawhatchee Elimia) Elimia buffyae Mihalcik & Thompson, 2002.

Widely distributed in the Choctawhatchee River system as far south as Washington and Walton Counties, Florida.

21b. Shell with or without bright bands; with low wavy growth wrinkles; large but not robust, 23-28 mm long. (Fig. 54). -----------------------------------------------------------------------------------(Escambia Elimia) Elimia annae Mihalcik & Thompson, 2002.

Found in the Conecuh River and some of it’s larger tributaries in Conecuh, Covington and Escambia Counties, Alabama. It may occur in the Conecuh River in Santa Rosa County, Florida, but it has not yet been found in Florida.

21c. Shell with or without bands; slender; Suture deeply impressed; upper whorls with a strongly carinate periphery (Fig, 55). ----------------------------------------------------------------------------------------------------------------------- (Dented Elimia) Elimia sp..

This and similar species are known from small streams in the Alabama River system in Sumpter, Marengo, Monroe and Wilcox Counties, and from small streams in the Escambia River system in Conecuh and Escambia Escambia Counties, Alabama. This group of species requires further study to resolve the number of species that are involved. The specimen in Fig. 55 is from Escambia Co., Alabama. It has not been found in Florida, but it may occur in small stream in Escambia and Santa Rosa Counties, Florida.

22a. Shell with spiral chords or spirally arranged series of nodes.----------------------------------------------------------------------21.

22b. Shell with strong vertical ribs on spire; spiral chords vestigial, confined to spiral series of knobs on top of vertical ribs; adults small, about 13-16 mm long (Fig. 56).--------------- (Goblin Elimia) Elimia vanhyningiana (Goodrich, 1921).

Confined to springs and smaller streams in the St Johns River system in the Florida Peninsula. Named after O. C. Van Hyning, founder of the Florida State Museum (Florida Museum of Natural History) and an ardent collector of mollusks.

23a. Shell unicolor, with distinct vertical sculpture in addition to strong spiral sculpture. Embryonic shell with a strong peripheral spiral chord that continues onto following whorls (Fig. 47). ----------------------------------------------------------------24.

23b. Shell with darker colored spiral chords that may be smooth or wavy. Vertical sculpture reduced to irregularly spaced and uneven growth striations or low undulating ribs. Embryonic shell smooth, without spiral chords (Fig. 48). Rather stocky, adult about 15-20 mm long (Fig. 57).---------------------- (Black-crested Elimia) Elimia albanyensis (Lea, 1864).

24a. Sculpture above periphery of whorls consisting of nodes arranged in vertical and spiral rows. Shell short and stocky. Adult size small, about 12-16 mm long (Fig. 58).--------------- (Knobby Elimia) Elimia athearni (Clench & Turner, 1956).

Occurs in the Chipola River in Jackson and Calhoun counties and in the Santa Fe River system, Columbia County. Frequently found with E. floridensis. When the two occur together, E. athearni usually inhabits rocks, while E. floridensis inhabits woody objects and the sandy substrata. Named after Herbert D. Athearn (1923 - ) of Cleveland, Tennessee, who has added greatly to our knowledge of the southeastern freshwater mollusks though his collecting efforts.

24b. Sculpture above periphery of whorls consisting of sharp spiral chords and distinct vertical ribs; shell attenuate.-- 25.

25a. Whorls straight-sided, not scalariform; suture hardly distinct; aperture terminating at periphery of last whorl; vertical ribs weaker and closely spaced; adult size about 25-30 mm long (Fig. 59).-------------------------------------------------------------------------------------------------------------------------------------------------------- (Slackwater Elimia) Elimia clenchi (Goodrich, 1924).

Confined to the Choctawhatchee River system in Florida and adjacent Alabama. Frequently found in quiet water on a silty substrate. Named after William J. Clench, a scholar of malacology.

25b. Whorls of spire weakly scalariform, causing the suture to be deeply incised. Aperture terminating below periphery of body whorl. Vertical ribs relatively strong and more widely spaced.-------------------------------------------------------------------- 26.

26a. Vertical ribs smooth along the periphery, strongly developed (Fig. 60) ------------------------------------------------------------------------------------------------------------------------------------------------------------------- (Waccasassa Elimia) Elimia floridensis ssp.

Confined to the Waccasassa River, Levy County

26b. Vertical ribs serrate along the periphery ------------------------------------------------------------------------------------------------- 27.

27a. Vertical ribs strongly developed, crossed by nearly equal sized spiral threads that form low spines where they cross the ribs, adults about 20-25 mm long (Fig. 61). -------------------------------- (Rasp Elimia) Elimia floridensis (Reeve, 1860).

Distributed from the Chipola River east and south to the Manatee River and the St. Johns Rivers systems in central Florida. Some populations are quite distinct in sculpture, and more than one species may be involved. Six forms have been named as different species. The typical form is illustrated.

27b. Vertical ribs reduced in size, but with bold spines at the periphery; spiral threads above periphery relatively weak; adults up to 35 mm long (Fig. 62). ------------------------------------------------------------------------------ (Spring Elimia) Elimia sp.

Confined to Holmes Creek, and headwater springs of the Chipola River, Florida.

28a. Central tooth of radula with long basocones along base (Fig. 36). Amphibious; moves by step-like mode of progression (Fig. 63).------------------------------- POMATIOPSIDAE (Slender Walker) Pomatiopsis lapidaria (Say, 1817).

This family of fresh and brackish water snails is found in Australia, southeast Asia, southern Africa, North America and South America. Pomatiopsis lapidaria is the only freshwater species that occurs in Florida. Shell elongate-conical, consisting of about seven strongly convex whorls, sculptured with fine growth striations; spiral sculpture absent; Peristome complete around aperture; adults about 6-7 mm long. Distributed from the Great Lakes region south to Virginia along the east coast and south through Alabama to Florida. In Florida it is found only in the Apalachicola River system. Amphibious, lives on damp ground and along seepage’s among dead leaves, sticks, and rocks.

Fig. 63

28b. Central tooth of radula with basocones located on fore or lateral wing of tooth (Figs. 34, 35). Aquatic; moves by gliding motion. Shell of various shapes and sculpture.----------------------------------------------------------- HYDROBIIDAE --- 29.

Hydrobiids are small- to medium-sized operculate snails that live primarily in brackish and fresh water. The HYDROBIIDAE include over 200 genera and approximately 1000 species. Most have monotonously simple, conical or depressed-conical shells that are nearly devoid of taxonomically useful characteristics. Essentially identical shells occur repeatedly among unrelated genera and subfamilies. Evolution has proceeded primarily through reproductive and trophic specializations. Important diagnostic characteristics for subfamilies, genera, and species are found in the female reproductive system, the male reproductive organ (the penis), and modifications of the radular teeth. The shell are secondarily useful for identification, but only when supplemented with anatomical information. The number of subfanilies recognized in the Hydrobiida is unsettled. Recent studies treat amnicolids as a separate families.

29a. Shell globose with a short depressed spire; body whorl ample; umbilicus closed.----------------------------------------- 30.

29b. Shell conical or cylindrical-conical in shape; spire elevated; body whorl not disproportionately voluminous; umbilicus closed or open.---------------------------------------------------------------------------------------------------------------------------------------- 32.

30a. Columellar margin of aperture wide, flat-faced; apex of spire usually erroded; apical whorls, when present, with minute spiral striations; central tooth of radula with basocones located on ridged surface of tooth (Fig. 34); penis frlattened, blade-like (Fig. 67). ------------------------------------------------------------------------------------- LITHOGLYPHINAE --- 31.

30b. Columellart margin of aperture not flat-faced; apex of shell usually entire; penis with large terminal lobe on left side and small appendage-like flagellum on right margin (Fig. 68); lobe and flagellum with various patterns of dermal glands; central tooth of radula with basocones located on reflected margin of tooth (Fig. 35).---------------------------------------------------------------------------------------------------------------------------------------------------------------------- NYMPHOPHILINAE (in part) --- 48.

Somatogyrus is distributed from the Mississippi River drainage system east to Atlantic coastal streams, and south to the Gulf coastal drainage systems. Approximately 35 species have been described. Three species are known from rivers entering northwest Florida from Georgia and Alabama.

31a. Adult shell about 4-5 mm high; umbilicus wide; columellar margin of the aperture concave in outline (Fig. 64). ---------------------------------------------------------------------------- (Gulf Coast Pebblesnail) Somatogyrus walkerianus (Aldrich, 1905).

Found in western Florida and southern Alabama from the Choctawhatchee River west to the Escambia River. This species inhabits silt and fine sand in quiet zones along the sides of larger rivers and streams.

31b. Adult shell small, less than 3 mm high; umbilicus narrow but not occluded by the columellar lip; columellar margin of the aperture weakly concave (Fig. 65).----------------------------------- (Choctawhatchee Pebblesnail) Somatogyrus sp.

Found on rock outcrops in the Pea and Choctawhatchee Rivers in Geneva Co. Alabama. Not yet recorded from Florida.

31c. Adult shells small, less than 3 mm high; umbilicus closed by the reflected columellar lip; columellar margin of the aperture nearly straight, barely convex (Fig. 66). ------------------------------------- (Apalachi Pebblesnail) Somatogyrus sp.

Known only from the shoals below Jim Woodruff Dam on the Apalachicola River, where it occurs on the limestone substrata.

32b. Penis with large a terminal lobe on the left side and a smaller appendix-like flagellum on the right side. Lobe and flagellum with various patterns of dermal glands (Fig. 68). -----------------------------------Subfamily NYMPHOPHILINAE---48.

33a. Penis with a single papilla along left margin (Fig. 69). Papilla with a duct that leads to a blind caecum in nape of snail. Vas deferens independent of blind caecum and its duct.-------------------------------------- Family AMNICOLIDAE --- 64.

33b. Penis with papillae along both margins, or right margin only (papillae absent in some Aphaostracon). Vas deferens the only duct present in penis (Fig. 70). -------------------------------------------------------------- Subfamily COCHLIONINAE --- 34.

34 Subfamily COCHLIOPINAE--------------------------------------------------------------------------------------------------------------------34a.

34a. Shell usually with raised spiral threads around periphery, frequently the uppermost thread has conical or triangular spines (Figs. 72-74). Female ovoviviparous with about 50 embryos in uterus; embryos clearly evident through clean shells. Penis with 3-7 papillae along right margin and a projection with 1-4 papillae near end on left side (Figs. 70, 71).-------------------------------------------------------------------------- (Serrated Crownsnail) Pyrgophorus platyrachis Thompson, 1968.

Shell elongate-conical with 5-6 whorls. Spire straight-sided. Suture deeply impressed. Color brown or olivaceous. Peristome complete around aperture. Length of female shell 3-5 mm. Sexually dimorphic in size; males about half as large as females. Found in brackish and freshwater throughout the southern quarter of the Florida peninsula. Abundant on aquatic vegetation.

34b. Shell without conical spines, although spiral threads may be present. Penis with different arrangement of papillae than above. Females ovoviviparous or oviparous.------------------------------------------------------------------------------------------ 35 .

35a. Shell elongate, thin, transparent, grayish. Suture deeply impressed. Female ovoviviparous with about 15 large embryos in uterus. Penis with large papilla on right margin near base and one or two papillae on left margin near distal end (Figs. 75, 76). Shell sexually dimorphic in size, males about one-third as long as females.------------------------------ 36.

35b. Shell variable in shape. Female oviparous, never with embryos in uterus. Penis without a conspicuously enlarged papilla near right base, although other papillae usually are present ------------------------------------------------------------------ 37.

36a. Shell elongate-conical, with about 5-7 whorls. Aperture broadly in contact with preceding whorl. Peristome incomplete around aperture. Umbilicus closed or narrowly perforate. Spiral or costate sculpture usually present. Female shell about 4-6 mm long (Figs. 77-79). Penis with 2 or 3 papillae on left margin (Fig. 75).--------------------------------------------------------------------------------------------------------------------- (Smooth-ribbed Hydrobe) Tryonia aequicostatus (Pilsbry, 1889).

Generally distributed in the central part of the Florida peninsula in rivers, springs, and lakes.

36b. Shell cylindric-conical with 4.5-5.0 whorls. Aperture free from, or only in slight contact with, preceding whorl. Peristome complete around aperture. Umbilicus open. Shell sculpture with incremental striations only. Female shell about 3.5-4.0 mm long (Fig. 80). Penis with one papilla on left margin (Fig. 76).----------------------------------------------------------------------------------------------------------------------------------------------- (Regal Hydrobe) Pseudotryonia brevissimus (Pilsbry, 1890).

Restricted to a small area in the central part of the Florida peninsula where it is found in marshy lakes and rivers.

37a. Shell conical, olivaceous in color. Peristome incomplete around aperture. Whorls flat-sided with suture weakly impressed. Sculptured with fine incremental striations and a few fine spiral striations (difficult to distinguish except with transmitted light). Sexes not conspicuously dimorphic in size. Penis with 7-50 papillae along right margin and 1-4 papillae along distal third of left margin (Figs. 81-83).-------------------------------------------- Littoridinops Pilsbry, 1952 --- 38.

37b. Shell conical or cylindric-conical; light to dark brown. Peristome complete around aperture. Whorls generally arched. Spiral sculpture absent. Sexes strongly dimorphic in size, males about half as long as females. Penis with 0-6 papillae confined to right margin (Figs. 89-91).--------------------------------------------------------- Aphaostracon Thompson, 1968 --- 40.

38a. Penis with 3 - I 0 small papillae around base and 7-15 papillae along right margin in a single row (Fig. 81). Sides of spire slightly convex. Parietal margin of operculum concave (Fig. 85). Shell with a brownish hue. Shell with 5.0-6.5 whorls; about 3-5 mm long (Fig. 84). ------------------------------------ (Henscomb Hydrobe) Littoridinops tenuipes (Couper, 1844).

Found in fresh and brackish water along the Atlantic coast of Florida north to Maryland.

38b. Penis without papillae around base.------------------------------------------------------------------------------------------------------- 39.

39a. Penis with 17-50 papillae along right margin arranged in 3-5 rows (Fig. 82). Parietal margin of operculum slightly convex in outline (Fig. 86). Shell highly variable in shape; freshwater forms olivaceous or brown; adults with about 4.5-6.0 whorls; about 3.5-4.5 mm long (Fig. 87).--------- (Cockscomb Hydrobe) Littoridinops monroensis (Frauenfeld, 1863).

Widely distributed in brackish marshes and streams from Georgia to Mississippi. Enters fresh water in Florida throughout the St. Johns River. An extremely variable species in which most variations occur in brackish habitats. The freshwater form is conservative in its shell characteristics.

39b. Penis with 5-15 papillae along right margin arranged in 1-2 rows (Fig. 83). Parietal margin of operculum convex. Shellolive-colored; spire straight-sided. Shell with 5.6-6.8 whorls; about 3.2-4.5 mm long (Fig. 88).------------------------------------------------------------------------------------------------------ (Bantam Hydrobe) Littoridinops palustris Thompson, 1968.

Confined to brackish marshes from Tampa Bay, Florida,north and west to Mobile Bay, Alabama.

40a. Penis with papillae along right margin (Figs. 89, 90).-------------------------------------------------------------------------------- 41.

40b. Penis simple, elongate-conical, without papillae (Fig. 91).------------------------------------------------------------------------- 42.

41a. Penis with 1-2 papillae.------------------------------------------------------------------------------------------------------------------------ 44.

41b. Penis with 3-5 papillae.------------------------------------------------------------------------------------------------------------------------ 46.

42a. Shell squat, compact, cylindric-conical in shape, thick and opaque. About 4.2-4.6 weakly arched whorls with a weakly impressed suture. Aperture comma-shaped, tightly appressed against preceding whorl. Length of shell about 2.2-2.8 mm long (Fig. 92).-------------------------------------------------- (Dense Hydrobe) Aphaostracon pycnus Thompson, 1968.

Endemic to Alexander Spring Run, Ocala National Forest, Lake County.

42b. Shell conical with strongly arched whorls and a deeply impressed suture.----------------------------------------------------- 43.

43a. Shell translucent. Body whorl inflated. Aperture elliptical and loosely attached to or slightly separated from preceding whorl; 4.5-4.9 whorls. Length of shell 2.6-3.0 mm (Fig. 93).--------------------------------------------------------------------------------------------------------------------------------------------------- (Clifton Spring Hydrobe) Aphaostracon theiocrenetus Thompson, 1968.

Endemic to Clifton Springs on the south shore of Lake Jessup, Seminole County, Florida.

43b. Shell very thin, fragile, transparent. Aperture elliptical and usually attached to preceding whorl; 4.1-4.5 whorls present. Length of shell 2.0-2.4 mm (Fig. 94).------- (Blue Spring Hydrobe) Aphaostracon asthenes Thompson, 1968.

Endemic to Blue Springs, Volusia County, Florida.

44a. Shell narrow, terete or cylindric-conical with a moderately impressed suture. Aperture broadly attached to preceding whorl across parietal wall. Whorls 4.6-5.3. Length of shell 2.4-3.4 mm (Fig. 95).----------------------------------------------------------------------------------------------------------------------------------------- (Slough Hydrobe) Aphaostracon rhadinus Thompson, 1968.

Abundant along the northern third of the St. Johns River system, Florida.

44b. Shell conical to elongate-conical; whorls 4.0-4.5 with a deeply impressed suture. Aperture narrowly in contact or free from preceding whorl. --------------------------------------------------------------------------------------------------------------------------------- 45.

45a. Shell conical to ovate-conical. Aperture broadly elliptical. Operculum with about 3 whorls (Fig. 96). Length of shell 2.0-2.4 mm (Fig. 98).-------------------------------------- (Suwannee Hydrobe) Aphaostracon hypohyalina Thompson, 1968.

Occurs in a small area in north-central Florida from the Suwannee River system west to small streams in Wakulla County.

45b. Shell elongate-conical. Aperture broadly ovate. Operculum with about 6 slowly expanding whorls (Fig. 97). Length of shell 2.2-2.6 mm (Fig. 99). ---------------------------------------------- (Wekiwa Hydrobe) Aphaostracon monas (Pilsbry, 1899).

Endemic to Wekiwa Springs, Orange County, Florida.

46a. Shell cylindric-conical, solid opaque; 4.5-4.9 moderately rounded whorls. Aperture ovate; broadly attached to preceding whorl. Length of shell 2.1-2.8 mm (Fig. 100). --------------------------------------------------------------------------------------------------------------------------------------------------------- (Thick-shelled Hydrobe) Aphaostracon pachynotus Thompson, 1968.

Found along the southeastern half of the Florida peninsula from the St. Johns River south to Dade County.

46b. Shell conical; thin and transparent; 4.0-4.5 strongly arched whorls. Aperture loosely attached to or widely separated from preceding whorl. ------------------------------------------------------------------------------------------------------------------------------- 42.

47a. Aperture loosely attached to or slightly free from preceding whorl. Length of shell 2.0-2.5 mm (Fig. 101). Penis with 3 papillae along right margin (Fig. 90). --------- (Fenney Spring Hydrobe) Aphaostracon xynoelictus Thompson, 1968.

Endemic to Fenney Springs, near Coleman, Sumter County, Florida.

47b. Aperture widely separated from preceding whorl. Length of shell 3.0-4.0 mm (Fig. 102a, 102b). Penis with 4-6 papillae along right margin (Fig. 89). -------------- (Freemouth Hydrobe) Aphaostracon chalarogyrus Thompson, 1968.

Endemic to Magnesia Springs, 3.7 miles west of Hawthorne, Alachua County, Florida.

48a. Shell globose or tear-shaped. Umbilicus closed. ------------------------------------------------------------------------------------- 49.

48b. Shell conical or cylindric-conical. Umbilicus open, although very narrow in some species; occasionally closed.-- 50.

49a. Shell medium-sized or large; 5.4-7.5 mm long; thick and opaque; ovate or globose; apical whorls depressed; sides of spire rounded; body whorl conspicuously enlarged, ample, rapidly descending to aperture along last half whorl. Columellar margin of aperture very thick but not reflected over umbilical area (Fig.103). Outer lip straight in lateral profiles. Penis with a small blade-like flagellum along right margin and a heavy mid-ventral ridge that bears 8-11 narrow transverse dermal glands; other glands present on terminal lobe and flagellum (Figs. 105, 106).------------------------------------------------------------------------------------------------------------------------------ (Alligator Siltsnail) NotogiIlia wetherby (Dall, 1885).

Widely distributed throughout the northern half of the Florida peninsula north to the Suwannee River and also in southern Alabama and western Florida in the Choctawhatchee River system. A second species, Notogillia sathon Thompson, (Satyr Siltsnail) (Fig. 104), occurs in the Ocmulgee River system in Georgia.

49b. Shell medium-sized, 3.0-3.8 mm long; thinner, translucent or transparent in life; tear-shaped; spire raised and nearly straight-sided, pointed; body whorl less conspicuously enlarged, not descending to aperture along last half whorl. Columellar margin of aperture wide, rounded in front like a spindle. Outer lip of aperture arched forward (Figs. 109a, 109b). Penis with a very long slender flagellum that extends beyond terminal lobe. A single glandular crest present on apex of terminal lobe (Figs. 107, 108).------------------------------- (Teardrop Snail) Rhapinema dacryon Thompson, 1969.

Rhapinema is a monotypic genus confined to the Chipola River and Holmes Creek in Jackson, Holmes, and Washington counties, Florida, and tributaries of' the lower Chattahoochee and Flint rivers in southeastern Alabama and southwestern Georgia. Found in quiet water among aquatic plants.

50a. Mantle richly marked with reddish-brown blotches and spots. Terminal lobe of penis slender. Penis with a large, blade-like flagellum with continuous heavy dermal glands along each side (Figs. 110, 111, 68). ------------------------------------------------------------------------------------------------------------------------------------------------- Spilochlamys Thompson, 1968 --- 51.

50b. Mantle spotted with black, shaded or unmarked; terminal lobe of penis with complex crests that cause it to look like an animal's head; flagellum slender, with scattered and discontinuous glands along edge (Figs. 115, 116). ---------------------------------------------------------------------------------------------------------------------- Floridobia Thompson and Hershler, 2002 ---52.

This genus contains three species. Two occur in Florida. One species, Spilochlamys turgida Thompson, 1969, the Pumpkin Siltsnail, (Fig. 112), occurs in the Ocmulgee River system in Georgia. The genus is difficult to diagnose by shell characters because the three species are very dissimilar. Spilochlamys is most similar to the next genus, Cincinnatia, from which its shell usually differs by having a more deeply impressed suture, more strongly shouldered whorls, and a wider umbilical perforation.

51a. Umbilicus narrow, without a strong circum-umbilical ridge, outer lip without a callus on inner surface. Penis as illustrated (Fig. 110). Shell with about 4.5-5.0 whorls; about 3.0-4.8 mm long (Fig. 113).--------------------------------------------------------------------------------------------------------------------------------- (Conical Siltsnail) Spilochlamys conica Thompson, 1968.

Found in springs and spring-fed streams in north-central Florida from the Withlacoochee north and west to the Choctawhatchee River system.

51b. Umbilicus widely perforate, accentuated by a strong circum-umbilical keel. Outer lip of aperture with a thick callus on inner surface. Penis as illustrated (Fig. 111). Shell with 4.4-5.0 whorls; about 3.7-5.2 mm long. (Fig.114). ------------------------------------------------------------------------------------------------------- (Armored Siltsnail) Spilochlamys gravis Thompson, 1968.

Confined to north-central Florida in the St. Johns drainage system from near Palatka south to the Wekiva River.

52a. Penis with a few simple scattered superior tubercles on outer surface; parapical crest on a low ridge; accessory crest and inferior crest absent (Fig. 115a, 115b). -------------------------------------- Floridobia floridana species-group --- 53.

This group contains six species in the Florida peninsula.

52b. Penis with some superior tubercles fused into a U-shaped crest; parapical crest raised on a fleshy pedicel; accessory crest and inferior crest usually present (Fig. 116a, 116b). --------- Floridobia vanhyningi species-group --- 58.

A group of seven species confined to the St. Johns drainage system. Important diagnostic features occur in the arrangement of glands on the penis.

53a. Spire long, 1.3-1.7 times length of aperture, convex in outline; shell relatively large and nearly cylindrical; 4.0-4.9 mm long; whorls 5.0-5.7, strongly rounded with a deeply impressed suture (Fig. 117). ---------------------------------------------------------------------------------------------------------------------------------------- (Crystal Siltsnail) Floridobia helicogyra (Thompson, 1968).

Endemic to springs and a spring-fed lagoon at Crystal River, Citrus County, Florida.

53b. Spire shorter, conical, 0.7-1.3 times length of aperture, nearly straight-sided in outline, suture of whorls weakly or moderately impressed. ----------------------------------------------------------------------------------------------------------------------------- 54.

54a. Shell minute, 2.0-2.3 mm long; thin and transparent; spire 0.7-1.1 times length of aperture; flagellum lacking glandular crests. shell with 3.9-4.2 whorls (Fig. 118).--------- (Ichetucknee Siltsnail) Floridobia mica (Thompson, 1968).

Confined to a small spring along the west bank of the Ichetucknee River, about a mile northeast of US Highway 27, Suwannee County, Florida.

54b. Shell larger, thicker, and opaque; spire 0.9-1.3 times length of aperture; with more than 4.2 whorls; penis flagellum with glandular crests. -------------------------------------------------------------------------------------------------------------------------------- 55.

55a. Shell medium-sized, 2.8 - 3.5 mm long; spire 0.9 - 1.1 times length of aperture; shell with 4.2-4.7 whorls (Fig. 119). ------------------------------------------------------------------------------ (Hyacinth Siltsnail) Floridobia floridana (Frauenfeld, 1863).

Found throughout the northern half of the Florida peninsula from Hillsborough and Orange counties north to the Suwannee River. Replaced along the northern half of the St. Johns River by the vanhyningi species group.

55b. Shell moderately large, 3.7-4.5 mm long; spire 1.00-1.35 times length of aperture; shell with 4.8-5.4 whorls. ------ 56.

56a. Aperture broadly ovate in shape; parietal wall weakly in contact or solute from body whorl; whorls more prominently arched and with a deeper impressed suture. (Fig. I20).------- (Enterprise Siltsnail) Floridobia monroensis (Dall, 1885).

Known only from Benson's Mineral Spring near Enterprise, Volusia County, Florida. Presently thought to be extinct, recent reports to the contrary not withstanding.

56b. Aperture elliptical or trapezoidal in shape. ---------------------------------------------------------------------------------------------- 57.

57a. Aperture elliptical in shape; spire slenderer and slightly convex in outline; suture moderately impressed suture; parapical crest reduced in size. (Fig. 121) ------------------------------------ -------------------------------(Flatwood siltsnail) Floridobia leptospira (Thompson, 2000).

Found in Glen Branch, about 0.5 miles south of the national forest Road 539, Ocala National Forest, Lake County, Florida. The type locality is reached where a hiking trail crosses the slough formed by the creek. The snail lives on dead leave, debris and in silt.

57b. Aperture trapezoidal in shape; spire more robust, straight sided; with a shallower suture; parapical crest large (Fig. 122) -------------------------------------------------------------------- (Alexander Siltsnail) Floridobia alexander (Thompson, 2000).

Occurs in Alexander Spring Run, Ocala National Forest, Lake Co., Florida. The shell is very similar to that of Floridobia petrifons, which is in a different species-group by virtue of the glandular pattern on the verge. In addition, the Alexander Siltsnail has an operculum of the type described in 58b. The operculum of Floridobia petrifons is differentiated in 58a.

58a. Operculum nearly multispiral with four large, slowly expanding whorls (Fig. 123). ----------------------------------------- 59.

58b. Operculum paucispiral, with about three rapidly expanding whorls (Fig. 124).---------------------------------------------- 60.

59a. Shell small, about 3.0-3.5 mm long; adult with 4.4-4.8 whorl; lower corner of aperture tending to be angulate with fluted channel (Fig. 125); accessory crest absent on penis.-------------------------------------------------------------------------------------------------------------------------------------------------------------------- (Seminole Siltsnail) Floridobia vanhyningi (Vanatta, 1934).

Confined to Seminole Springs, 3.4 miles northeast of Sorrento, Lake County, Florida.

59b. Shell large, 3.7-4.5 mm long; adults with 4.6-5.3 whorls; lower corner of aperture slightly extended forward as a weak, tongue-like projection (Fig. 126); accessory crest present on penis.----------------------------------------------------------------------------------------------------------------------------------------- (Rock Springs Siltsnail) Floridobia petrifons (Thompson, 1968).

Emdemic to Rock Springs, 6.5 miles north of Apopka, Orange County, Florida.

60a. Shell minute, 2.4-2.7 mm long; adults with 3.9-4.2 whorls; spire short, 0.8- 1.1 times height of aperture (Fig. 127); superior tubercles on penis arranged in oblique longitudinal series.----------------------------------------------------------------------------------------------------------------------------------------------------------------- (Pygmy Siltsnail) Floridobia parva (Thompson, 1968).

Endemic to Blue Springs, Volusia County, Florida.

Fig. 127

60b. Shell larger, 2.8-4.6 mm long; adults with 4.0-4.9 whorls; spire longer, 0.9-1.3 times height of aperture; superior tubercles not arranged in oblique longitudinal series.-------------------------------------------------------------------------------------- 61.

61a. Shell large, 4.0-4.6 mm long; thick and opaque. Whorls globose, with a deeply impressed suture. Penis with two or more longitudinal crests within U-shaped superior tubercle (Fig. 128).----------------------------------------------------------------------------------------------------------------------------------------------- (Ponderous Siltsnail) Floridobia ponderosa (Thompson, 1968).

Endemic to Sanlando Springs,Seminole County, Florida.

61b. Shell 2.8-3.7 mm long. Thin and translucent or transparent. U-shaped superior crest not enclosing longitudinal crests.----------------------------------------------------------------------------------------------------------------------------------------------------- 62.

62a. Shell conical, spire moderatly high. Suture relatively deep, Whorls of spire rounded. Penis with invaginated cave-like pit within U-shaped superior tubercles.---------------------------------------------------------------------------------------------------------- 63.

62b. Shell elongate conical, spire high. Suture relatively shallow. Whorls of spire less rounded. Penis with superior tubercles forming a vague broken loop; invaginated cave-like pit absent. Parapical crest of verge greatly enlarged. Penis filament white. (Fig. 129).--------------------------------------------------- (Creek Siltsnail) Floridobia fraterna (Thompson, 1968).

Found in small streams along the east side of the St. Johns River from Palatka north and in some streams of Putnam County, Florida.

63a. Penis with a dense pattern of superior tubercles. Inferior crest absent. Accessory crest present. Penis filament white. (Fig. 130).---------------------------------------------------------- (Wekiwa Siltsnail) Floridobia wekiwae (Thompson, 1968).

Endemic to Wekiwa Springs, Seminole County, Florida.

63b. Dorsl surface of penis with a few elongate superior tubercles that form a weakly defined U-shaped pattern. Accessory crest absent. Inferior crest usually present. Penis filament black. (Fig. 131).------------------------------------------------------------------------------------------------------------------------ (Green Cove Springsnail) Floridobia porterae Thompson, 2000).

Endemic to Green Cove Spring Run, in the municipality of Green Cove Springs, Clay County. Florida. The shell is strikingly similar to Floridobia wekiwae. No constant difference between the two species is apparent in the shell. They are separated geographically by a distance of about 75 miles.

64a. Shell small, 2.0-2.8 mm long. Nuclear whorl slightly protruding, 0.29-0.41 mm in diameter transverse to initial suture. Mantle diffusely pigmented or unpigmented. ------------------------------------------------------------------------------------------------- 65.

64b. Shell larger, 2.2-4.8 mm long. Nuclear whorl flattened, 0.41-0.48 mm in diameter transverse to initial suture. Mantle mottled with black spots and blotches. ---------------------------------------------------------------------- Amnicola Gould, 1841--- 66.

65a. Shell smooth. Conical with relatively slender whorls. Widely umbilicate. Basal lip of peristome deeply receded. Nuclear whorl 0.29-0.33 mm in diameter. Mantle diffusely pigmented with melanophores (Fig. 132).--------------------------------------------------------------------------------------------------------- (Indented Duskysnail) Lyogyrus retromargo Thompson, 1968.

Known from a narrow zone across the neck of Florida peninsula. The extent of distribution north and west of there is not yet determined. Commonly found in quiet water among dead leaves and vegetation.

Lyogyrus Gill, 1863 consists of two subgenera, Lyogyrus s. s. with eight species, and Spirogyrus with a single species confined to south-central Georgia. The latter, (Cobble Sprite) Lyogyrus (Spirogyrus) latus Thompson and Hershler, 1991, occurs under flat rocks and wood. It is found in the Ocmulgee River and in the lower Flint River system. It may occur in Florida (Fig. 133).

65b. Shell shaggy with numerous spiral fimbriations that are broken into synchronized tufts. Conical with relatively obese whorls. Narrowly umbilicate. Nuclear whorl 0.41 mm in diameter transverse to initial suture. Transparent white (134). ---------------------------------------------------------------------------- (Shaggy Ghostsnail) Dasyscia franzi Thompson & Hershler, 1991.

A montotypic genus nown only from a subterranean stream at Blue Spring Cave, Washington County. The species is named for Richard Franz, in recognition for his many contributions to the biology of cave systems in Florida and adjacent regions of the Southeast.

Amnicola is a widespread genus in temperate North America. Four species currently are recognized, but the genus has received very little study over most of its range. The specie prefer quite clear water, of lakes and backwaters of streams andsprings.

66a. Shell conical, thick, opaque. Umbilical perforation wide, 1/6 to 1/8 diameter of shell. Whorls 3.8-4.3. Incremental striations intensified near nucleus and umbilicus. Aperture rhomboid; baso-columellar angle extended as slight tonguelike projection; basal lip broadly but shallowly indented (Fig. 135).------------------------------------------------------------------------------------------------------------------------------------ (Squaremouth Amnicola) Amnicola rhombostoma Thompson, 1968.

66b. Shell conical or globose-conical; thin, translucent, occasionally opaque. Umbilical perforation narrow, 1/8 - 1/10 diameter of shell. Whorls 3.0-4.0. Incremental striations uniformly weak. Aperture ovate; baso-columellar angle not extended; basal lip not indented.------------------------------------------------ (Peninsula Amnicola) Amnicola dalli ssp.--- 67.

67a. Operculum tightly coiled with four slowly expanding whorls (Figs. 136, 138).------------------------------------------------------------------------------------------------------------------------------------------------------ Amnicola dalli. dalli (Pilsbry and Beacher, 1892).

67b. Operculum loosely coiled, with 3.75 large whorls, the outer one expanding more rapidly than the others (Figs. 137, 139).------------------------------------------------------------------------------------------------------ Amnicola dalli johnsoni Pilsbry, 1899.

Found throughout the middle third of Florida peninsula. Most commonly found in sand-bottomed lakes and streams.