Cyrenoida floridana (Dall, 1896)

Valentas-Romera, Barbara L., Simone, Luiz R. L., Mikkelsen, Paula M. & Bieler, Ruediger, 2019, Anatomical redescription of Cyrenoida floridana (Bivalvia, Cyrenoididae) from the Western Atlantic and its position in the Cyrenoidea, Zoosystematics and Evolution 95 (2), pp. 517-534 : 517

Cyrenoida floridana (Dall, 1896) Figs 1-10 , 11-24 , 25-34 , 35-41

Cyrenoidea floridana Dall 1896: 52; Simpson 1887-1889: 66 [nomen nudum]; Dall 1889: 50, 208 [nomen nudum]; Rhoads 1899: 48; Heard 1975: 22; 1982a: 23, fig. 24; 1982b: 131.

Cyrenoida floridana - Dall 1901: 817, pl. 42, fig. 7; Lamy 1920: 388; Pilsbry and Zetek 1931: 69; Smith 1951: 45 (pl. 16, fig. 11, pl. 18, fig. 8); Pulley 1952: 114-115, pl. 9, fig. 15; Morrison 1954: 9-10; van Regteren Altena 1968: 157, 176; 1971: 5, 41, fig. 14; Wass 1972: 123; Abbott 1974: 466 (fig. 5383); Leathem et al. 1976: 93, figs 1-3; Kat 1978: 1-168, figs 1-91, tables 1-7; A1-A6; Neck and Herber 1981: 35-39; Kat 1982: 47, figs 1-3 (oocytes); Heard 1982a: 25, fig. 28j; Vokes and Vokes 1983: 39, 62, pl. 39, fig. 7; Neck 1985: 5; Bishop and Hackney 1987: 141, fig. 6; Turgeon et al. 1988: 36; 1998: 39; Camp et al. 1998: 11; Abbott and Morris 1995: 53, pl. 24, fig. 12; Redfern 2001: 219, pl. 92, fig. 898; Reece et al. 2004: 1116; Mikkelsen and Bieler 2000: 373; 2004a: 513; 2004b: 596; Lee 2009: 28, fig.; Turgeon et al. 2009: 728; Taylor et al. 2009: 10 (figs 4-8); Tunnell et al. 2010: 345; Redfern 2013: 400, fig. 1067; Bieler et al. 2014: 45 (fig. 3N); Arzul and Carnegie 2015: 33; González et al. 2015: 4, figs 1, 2; Combosch et al. 2017: table 1, figs 1, 2; Lemer et al. 2019: figs 1, 2.

Cyrenella floridana - Walker 1918: 88, fig. 232.

Cyrenoidea guatemalensis Pilsbry 1920: 221 (pl. 11, fig. 9); Clench and Turner 1962: 60.

Cyrenoida guatemalensis - Pilsbry and Zetek 1931: 69; Morrison 1946: 45.

Description.

Shell ( Figs 11-23 ): External features: Outline rounded, subcircular with ventral margin slightly posteriorly carinated ( Figs 11 , 12 ); equivalve, equilateral, ~6% longer than high, reaching maximum length of ~15 mm. Laterally inflated, width ~59% of total shell length ( Figs 13-15 ). Externally white, adorned only with growth lines, showing ~3 thicker commarginal growth increments. Periostracum thin, slightly wrinkled, light brown. Walls thin, fragile. Umbones prosogyrous, low, ~5% of total shell height, large, length ~25% of total shell length, located at midpoint of shell length. Ligament parivincular, opisthodetic, long, ~39% of total shell length ( Figs 15-17 ). Nymph long, ~20 times longer than wide, rectangular. Lunule and escutcheon absent. Internal features: Internal surface opaque white ( Figs 16 , 17 ). Adductor muscle scars and pallial line weak, very faintly impressed (outlined in Fig. 16 ). Anterior adductor muscle scar reniform, occupying ~1.5% of total internal surface; ventral portion ~2 times wider than dorsal portion; positioned at median third of valve height. Posterior adductor muscle scar oval, slightly pointed dorsally, occupying ~1.6% of total internal surface; located slightly more ventral than anterior muscle scar. Pallial line weak, formed by row of small pallial muscle scars, connected to middle portion of ventral surface of anterior adductor muscle to middle portion of ventral surface of posterior adductor muscle, inset from ventral shell margin by ~19.5% of total shell height, without pallial sinus. Microtubules of elongated conical shape, beginning with circular opening in interior shell wall, tapering toward but not reaching external surface ( Figs 20-22 ). Internal surface of shell usually with aragonitic nodules of various sizes and quantities ( Figs 16 , 17 , 23 ).

Hinge ( Figs 16-19 ): Hinge restricted to central and anterior portion of dorsal margin, composed of lateral and cardinal teeth. Right hinge ( Figs 17 , 19 ): Dental shelf short and wide, triangular, running along entire length of anterior portion of dorsal margin, height equivalent to ~10 times dorsal margin width; composed of two laterals and two cardinals. Each cardinal tooth joining posteriorly with a lateral tooth, forming two inverted-V-shaped teeth, one large ( Fig. 19 : lv), one small ( Fig. 19 : sv). Large V-shaped tooth located near dorsal shell margin, formed by long and laminar lateral tooth ( Fig. 19 : t1) and short cardinal one ( Fig. 19 : t2). Lateral tooth length equivalent to ~56% of total dental shelf length, cardinal tooth length equivalent to ~22% of lateral tooth length; small V-shaped tooth located ventral to large V-shaped tooth (lv). Small lateral tooth ( Fig. 19 : t3) length ~30% shorter than large lateral tooth, whereas small cardinal tooth ( Fig. 19 : t4) ~40% shorter than dorsally located cardinal tooth ( Fig. 19 : t2). Left hinge ( Figs 16 , 18 ): Dental shelf narrow, fusiform, running along 30% of anterior portion of dorsal margin, height equivalent to ~3 times dorsal margin width; composed of three cardinal teeth, two cardinal and one lateral, forming horizontal reversed F-shaped tooth ( Fig. 18 : fs). Both cardinal teeth originating parallel and close to each other, ( Fig. 18 : t6, t7). Lateral tooth laminar ( Fig. 18 : t5), joining anterior cardinal tooth ( Fig. 18 : t7), length equivalent to 50% of total length of dorsal shelf. Both cardinal teeth equivalent to 20% of lateral tooth length. When articulated, left valve tooth complex (t5-t7) fits within groove between right valve t3-t4 and t1-t2.

Muscular system ( Figs 25-27 , 31 , 34 , 33 ): Anterior adductor muscle (aa) reniform in cross section, ~3 times taller than wide; ventral portion ~2 times wider than dorsal portion; occupying ~3% of total shell internal volume; located at middle third of shell height; clearly divided into quick and slow components ( Figs 25 , 26 , 35 ), quick component occupying ~39% of anterior portion of muscle, dark grey in color, slow component occupying ~61% of posterior portion of muscle, light cream in color. Posterior adductor muscle (pa) elliptical in cross section, ~1.5 times wider than tall, ~20% shorter and ~2 times wider than anterior adductor muscle, occupying ~3% of total shell internal volume; located slightly ventral to anterior adductor muscle; clearly divided into quick and slow components ( Figs 25-27 , 34 , 35 ), quick component occupying ~52% of posterior portion of muscle, dark grey in color, slow component occupying ~48% of anterior portion of muscle, light cream in color. Paired anterior pedal retractor muscles (ar) oval in section, thin, attached on shell at posterodorsal side of anterior adductor muscle insertion, area ~3% of that of adductor, length ~20% of shell length, left and right branches fused at mid-length. Paired posterior pedal retractor muscles (pr) oval in cross section, slightly laterally compressed, thin, ~40% longer than anterior pedal retractors; inserting on shell dorsally posterior adductor muscle, in area ~3% of that adductor, left and right branches fusing at dorsal ~20% of total muscle length. Pedal protractor muscles absent. Two pairs of siphonal retractor muscles ( Figs 27 , 31 , 33 ); dorsal siphonal retractors (dm) ~3 times longer than wide; insertion at mantle bifid for half of total muscle length, 2 times as long as excurrent opening, originating laterally at half of siphonal base height; ventral siphonal retractors (vm) thin and translucent, ~3 times longer than wide, length ~50% of total length of dorsal siphonal muscle, originating at ventral end of incurrent siphon base.

Foot ( Figs 25 , 26 , 33 ): Foot short, wedged-shaped, length equivalent to ~35% of total shell length, contracted height equivalent to ~27% of total shell height, laterally compressed, with small heel of length equivalent to ~23% of total foot length. Distal end acuminate. Byssal groove and byssus absent in adults.

Mantle ( Figs 25-29 ): Mantle lobes symmetrical, thin, translucent white. Pallial muscles long, triangular, inserting from inner mantle fold region to ~16% of total mantle lobe height, arranged sparsely at ventral margin of mantle lobe; separated from each other by ~4 times pallial muscle basal width ( Fig. 25 : pm). Mantle border with three folds ( Fig. 29 ); outer fold (of) thin, width ~5% of shell thickness, 5 times higher than wide; middle fold (mf) similar to outer fold, ~30% shorter; inner fold (if) short, ~3 times taller than wide. Middle fold with 30 small and short papillae, bordering entire pedal gape portion ( Fig. 26 : pp); each papilla taller than wide, with rounded tip, separated from adjacent papillae by width equivalent to 4 times papillar width. Periostracum between outer and middle folds. Mantle lobes totally free except for siphonal area. Anterior mantle fusion occurring at ~42% of anterior adductor muscle height; posterior mantle fusion occurring at ~70% of posterior adductor muscle height ( Fig. 26 ). Siphonal area corresponding to ~30% of total mantle lobe length ( Fig. 26 ). Incurrent and excurrent siphons originating from inner mantle fold; siphonal area equivalent to ~35% of total animal height and ~7% of length ( Figs 26 , 27 ); siphons externally fused, covered by small brown spots, internally separated by thick, smooth muscular wall ( Figs 27 , 28 , 31 ); siphonal internal openings free, opening directly into pallial cavity; incurrent and excurrent siphons similar in size; ~5 times longer than wide; incurrent siphonal external tip bordered by one row of short papillae, papillae length equivalent to ~10% of total siphon length ( Fig. 28 : pp); excurrent siphonal tip with siphonal membrane ( Fig. 28 : sm).

Pallial cavity ( Figs 25 , 26 , 30 , 32 , 33 ): Occupying ~50% of total internal shell volume ( Fig. 25 ). Labial palps small, ~2% of total internal shell volume, triangular ( Figs 26 , 32 ), external surface smooth; outer (op) and inner hemipalps (ip) of similar size, ~60% narrower and 55% shorter than anterior adductor muscle insertion; outer hemipalp connected to mantle lobe by dorsal edge, at ~30% of palp length; inner hemipalp connected to visceral mass by dorsal edge, at ~20% of palp length; internal surface of each palp with ~10 tall, rounded transverse folds covering ~90% of inner palp surface, leaving thin smooth area at palp edges, corresponding to ~10% of total inner palp area. Folds decreasing in length toward mouth, forming shallow channels directed to anterior and posterior portions of mouth ( Fig. 32 ). Gill wide, ~60% times wider than outer hemipalp, equivalent to ~30% of total valve area ( Fig. 25 ). Ctenidia eulamellibranch with two demibranchs ( Fig. 30 ). Outer demibranch, fusiform, twice as long as wide; folded upon ~30% of its own area; covering pericardial and renal areas; connected to mantle lobe by tissue for ~15% of posterodorsal border length ( Fig. 25 ); inner demibranch triangular, ~1.5 times longer than wide; folded upon 50% of its own area; covered by outer demibranch in area equivalent to ~20% of its own area; food groove along ventral surface of inner demibranch ( Figs 30 , 33 : fg); demibranchs connected to each other at posterior end by tissue (gf), fusion length equivalent to 25% of total gill length ( Figs 25 , 33 ); each demibranch thin, fragile, without signs of chemosymbiotic bacteria ( Figs 24 , 30 ). Suprabranchial chamber ~1/3 of infrabranchial chamber volume ( Fig. 26 ).

Visceral mass ( Fig. 26 ): Triangular, occupying half of total internal shell volume, laterally flattened, 2 times as wide as muscular base; ~40% of anterodorsal portion filled by brown digestive gland (dg); remaining area filled by cream-colored gonad (go). Stomach and style sac located vertically in central portion of visceral sac.

Circulatory and excretory systems ( Figs 26 , 34 ): Pericardium located in posterodorsal region of visceral sac, between posterior region of umbonal cavity and dorsal surface of kidney ( Fig. 34 ), ~2 times as long as wide; occupying ~25% of total visceral mass volume. Paired auricles (au) anteroposteriorly elongated, connecting to main axis of gills along ~1/3 of gill length; walls thin, translucent. Ventricle (ve) elongated, thick, located at central pericardial region, surrounding ~45% of intestine crossing pericardial area, connected to auricles at median portion of lateral walls. Kidney light brown, triangular, located posteroventral to visceral mass, between ventral wall of pericardium and dorsal surface of posterior pedal retractor muscles, occupying ~25% of total visceral mass volume. Nephropores ( Fig. 26 : np) small, located at anterior third of kidney length, near genital pore ( Fig. 26 : gp).

Digestive system ( Figs 35-37 ): Palps and digestive gland as described above. Mouth small, located centrally between pairs of inner and outer labial palps. Esophagus (es) long, narrow, length ~30% and height ~10% of visceral sac length and height ( Fig. 35 ), cylindrical, running separate from anterior adductor muscle between and parallel to anterior portion of paired anterior pedal retractor muscles; internal surface covered by longitudinal folds, forming esophageal rim at stomach entrance ( Fig. 37 , er) in anteroventral region. Stomach (st) wide, occupying ~30% of visceral sac volume, conical, funnel-like, located anterior to umbo ( Fig. 35 ); length ~60% of total visceral sac length, ~30% of its height; posterior portion ~60% taller than anterior portion. Paired apertures to digestive caeca located ventrolaterally, turned toward ventral portion of visceral sac, located side by side at anterior portion of stomach. Dorsal hood (dh) long, thin, length ~40% of total stomach length, anteriorly bluntly pointed. Left pouch (lp) located below anterior portion of dorsal hood, shallow, wide, occupying ~20% of external area of left stomach wall, with ducts to digestive gland connecting at its central region ( Fig. 36 : dd). Stomach internal surface mostly smooth, with three well-developed sorting areas ( Fig. 37 ); first sorting area starting at left side of esophageal rim, running along dorsal wall of anterior stomach chamber, penetrating dorsal hood, narrow, comprised of small transverse folds (sa 1). Second sorting area originating ventral to first sorting area, at left side of esophageal rim, running along left wall of anterior stomach chamber, entering left pouch and dorsal hood, both on their ventral surfaces, broad, formed by thickening of stomach wall (sa 2).Third sorting area starting inside dorsal wall of dorsal hood, running along dorsal and right walls of posterior stomach chamber, until diffusing on ventral portion of right wall (sa 3). Gastric shield (gs) located at central dorsal wall, occupying ~40% of total gastric area, with two anterior projections, one dorsal at left border, penetrating dorsal hood, and one left ventral, penetrating left pouch. Two narrow, tall gastric ridges running along ventral stomach chamber, forming major and minor typhlosoles at style sac entrance ( Fig. 37 ). Longer ridge originating posterior to left caecum, penetrating caecum and exiting its anterior end, running toward anterior portion of stomach, performing curve, penetrating anterior end of right caecum, exiting that caecum at its posterior end, penetrating style sac at its right side, forming major typhlosole (mt). Shorter fold originating at style sac entrance, at region of major typhlosole penetration into style sac, forming rim bordering style sac entrance and ultimately minor typhlosole (nt). Style sac (ss) connecting stomach ventrally ( Fig. 35 ), tapering ventrally, ~3.3 times longer than wide, occupying ~12% of visceral sac total volume; style sac height equivalent to 50% of visceral sac length, and ~10% of its width. Intestine (in) thin, long, originating between typhlosoles, merging with style sac initially, narrowing after ventral end of style sac, passing ventrally below central stomach, penetrating pedal musculature at ~5% of foot height, contacting dorsal surface of posterior pedal retractor muscles, curving toward right, following posterodorsal portion of visceral sac, parallel to style sac; intestine total length ~7 times longer than style sac. Anus simple, sessile, on ventral surface of posterior adductor muscle ( Fig. 31 , 35 : an).

Reproductive system ( Fig. 26 ): Gonads with branched aspect, opaque, cream-colored. Paired gonoducts connected to gonadal acini branches along posterodorsal portion of visceral sac. Genital pores simple (gp), located at posterior portion of visceral mass, at ~20% of visceral mass height, near nephropore (np).

Central nervous system ( Figs 38-41 ): Paired cerebral ganglia ( Figs 38 , 41 : cg) surrounding dorsal surface of anterior esophagus, dorsal to external surface of outer labial palp, triangular, longer than wide ( Fig. 38 ), length 50% of esophageal length. Each cerebral ganglion ~50% width of transverse section of esophagus. Cerebral commissure ~50% longer than ganglia length; anterior adductor muscle nerve (na) originating at anterior end of cerebral ganglion, contacting posterior surface of anterior adductor muscle, bifurcating into two main branches; internal branch penetrating posterodorsal third of muscle, diffusing into muscle; outer branch bordering posterior surface of anterior muscle until contacting pallial region and diffusing into muscle. Two additional pairs of nerves originating dorsally on cerebral ganglia, anterior to cerebrovisceral connective (cv) crossing visceral mass, contacting gonopore dorsally, bordering anterior portion of kidney and connecting dorsally with visceral ganglia, connecting cerebropedal connective (cp) running immersed in pedal muscles, connecting to anterior region of paired pedal ganglia ( Figs 40 , 41 : pg). Paired visceral ganglia ( Figs 39 , 41 : vg) fusiform, of similar length and height, length ~60% of cerebral ganglia length, partially fused medially, with subcentral groove; located ventral to paired posterior pedal retractor muscle, parallel with posterior adductor muscle, at dorsal tip connecting to cerebrovisceral connective (cv, as described above) and renal nerve (rn), penetrating kidney area; laterally originating ctenidial nerves (cn) running through central axis of posterior portion of gills; dorsally originating posterior adductor muscle nerve, penetrating mid-region of anterior surface of posterior adductor muscle; at ventral tip originating pallial nerve (pn), contacting anterior surface of ventral portion of posterior adductor muscle, running toward incurrent and excurrent siphonal muscles, reaching excurrent opening, originating single, short nerve (sn) that runs parallel to ~25% of dorsal siphonal muscle length, continuing parallel to mantle border, diffusing into mantle lobe edge. Paired pedal ganglia totally fused ( Figs 40 , 41 : pg), oval, longer than wide, ~20% wider than visceral ganglia; located internal to posterior pedal retractor muscles, dorsal to foot insertion, at anterior tip connecting with cerebropedal connectives from cerebral ganglia; at posterior tip connecting two pairs of nerves, with dorsal pair running toward posterior region, inside posterior pedal retractor muscles; posteroventral pair curving ventrally, running into foot.

Habitat.

Infaunal, in muddy sand; usually positioned vertically in about 2 cm depth ( Kat 1978), in mangrove areas and brackish waters.

Measurements.

(length by height by width, in mm): FMNH 328260 (specimen #1 of 4): 14.2 × 13.4 by 8.5; UF 122840 #1: 12.5 × 11.4 × 8; UF 264025 #1: 10.8 × 10.3 × 5.6; #2: 14.18 × 13.55 × 8.55.

Distribution.

USA: eastern coast from Delaware to the Florida Keys, and Gulf of Mexico coast from western Florida to Texas; Bahamas; Mexico: Yucatan, Quintana Roo; Guatemala; Bonaire ( Lee 2009); Suriname.

Type material.

Syntypes: Cyrenoidea floridana : United Stated Of America • Florida, Fort Myers, Everglades; 2 specimens; USNM 87735. Marco Island; 3 specimens; USNM 60974. 3 specimens, USNM 60975; Boca Ciega Bay; 3 specimens; USNM 60973. St Johns River mouth; 10 specimens; USNM 46846 ( Figs 1-4 ). Georgia, Brunswick Island; 30 specimens; USNM 129197. Cyrenoidea guatemalensis : Lectotype: Guatemala • Livingstone; ANSP 107532 ( Figs 5-10 ). Note: Pilsbry’s (1920) description of C. guatemalensis can be read as having been based on a single specimen and van Regteren Altena (1971: 41) interpreted the specimen of ANSP 107532 as a holotype. However, Pilsbry is known for imprecisely indicating the type material at hand (P. Callomon, G. Rosenberg pers. comm.) and the existence of more than one original type specimen cannot be excluded. We accept van Regteren Altena’s (1971) action as a fixation of lectotype by inference of holotype under ICZN (1999) Article 74.6.

Examined material.

United Stated Of America • 10 valves; Delaware, Kent County, Bombay Hook; 01 Aug. 1954; Morrison and Rosso leg.; USNM 777892. • 10 valves; New Jersey, Delaware Bay, Cumberland County, Fortescue; 15 Jul. 1957; J.P.E. Morrison leg.; USNM 777894. • 6 valves; Delaware Bay, Cumberland County, Dividing Creek; J.P.E. Morrison leg.; 15 Jul. 1957; USNM 777895. • 20 valves; Maryland, Dorchester County; J.P.E. Morrison leg.; 11 Jul. 1954; USNM 777893. • 10 valves; Dorchester County, near Elliot, gullet of black duck; F.M. Uhler leg.; USNM 592260. • 8 valves; Queen Anne’s County; 11 Jul. 1954; J.P.E. Morrison leg.; USNM 777890. • 12 valves; Arundel County, Deale, marshy, head of small inlet; 11 Jul. 1953; J.P.E. Morrison leg.; USNM 777887. • 6 valves; Arundel County; 15 Jul. 1953; J.P.E. Morrison leg.; USNM 777889. • 4 valves; Arundel County, Deale; 13 Jun. 1954; J.P.E. Morrison leg.; USNM 777888. • 6 valves; North Carolina, Beaufort, under algal mats; R.W. Heard leg.; USNM 678947. • 1 specimen; South Carolina, Horry/Georgetown counties, Murrell’s Inlet, in black muddy sand under log near high tide line, S. edge of inlet along road; 03 Dec.1955; J.P.E. Morrison leg.; USNM 1437782. • 6 valves; Georgia, McIntosh County, Fort King George Historic Site, Darien, exposed under drift logs and boards; 15 Dec. 1954; Cmdr. Miller leg.; USNM 707264. • 4 valves; Glynn County, Saint Simons Island; Oct.1938; H.A. Rehder leg.; USNM 535386. • 1 valve; Mississippi, Jackson County, Halstead Bayou; Gulf Coastal Marine Laboratory leg.; UF 246126. • 15 valves; Florida, Wakulla County, St. Marks; 17 Jun. 1958; United States Fish and Wildlife Service leg.; USNM 612256. • 5 valves; Saint Johns County, Saint Augustine; F.E. Spinner leg.; ANSP 54330. • 6 valves; Saint Johns County, Halifax River; USNM 253659. • 12 valves; Volusia County, Daytona [Beach]; C.W. Johnson leg.; USNM 336943. • 2 valves; Marion County, creek SE of Ocala; 15 May. 1928; T. Van Hyning leg.; ANSP 152656. • 8 valves; Citrus County, Homosassa; E. Roper leg.; USNM 131462. • 4 specimens; Hernando County; G. Prime leg.; ANSP 68457. • 25 specimens; Hernando County, Aripeka; G. Prime leg.; ANSP 73905. • 20 valves; Pasco/Hernando counties, Aripeka; L. Pine leg.; USNM 149932. • 10 valves; Hernando County, Little Blind Creek; 04 Dec. 1927; T. Van Hyning leg.; ANSP 149568. • 1 valve; Pasco/Hillsborough counties, Hillsborough River; E.J. Post leg.; USNM 591792. • 6 valves; Charlotte County, Punta Gorda; 1928; J.L. Madden leg.; USNM 592290. • 1 specimen; Glades County, Caloosahatchee River; C.W. Johnson leg.; ANSP 62888. • 5 valves; W Florida; C.W. Johnson leg.; ANSP 59610. • 30 valves; Collier County, Carnestown; 12 Apr. 1928; T. Van Hyning leg.; ANSP 152655. • 4 valves; Dade County, Miami; Olsen leg.; USNM 153404. • 10 valves; Dade County, Miami; 07 Apr. 01; Benedict leg.; USNM 330959. • 10 specimens; Dade County, Miami; S. N. Rhoads leg.; ANSP 77046. • 8 valves; Dade County, Miami; S. N. Rhoads leg.; ANSP 189416. • 16 valves; Lee County, Fort Myers; Hend. leg.; USNM 455820. • 16 valves; Lee County, Fort Myers; Henderson leg.; UNSM 425820. • 2 valves; Lee County, Fort Myers, Everglades; 1896; C.W. Johnson leg.; USNM 87735; syntype. • 20 valves; Monroe County, Big Pine Key; C. Margaret leg.; UF 122840. • 14 valves; Florida Keys, Monroe County, Big Pine Key; 27-28 Dec. 1956; C. Phillips, F. Philips leg.; FMNH 63059. • 31 valves; Florida Keys, Monroe County, pond on Big Pine Key; 1968; M. Teskey leg.; FMNH 293174. • 4 specimens + 15 valves; Florida Keys, Monroe County, Blue Hole quarry on Big Pine Key, Florida Keys; 024°42'21"N, 081°22'49"W; shoreline sediment at base of vegetation, salinity measured at 3 ppt; sta. FK-727; 03 May. 2004; R. Bieler, P.M. Mikkelsen leg.; FMNH 328260. • 67 valves; Florida Keys, Monroe County, Blue Hole quarry on Big Pine Key; 024°42'24"N, 081°22'48"W; sta. FK-794; 18 Nov. 2007; R. Bieler, P. Sierwald, E.A. Glover, J.D. Taylor leg.; same locality as in study by Taylor et al., 2009; FMNH 333534. • 5 valves; Florida Keys, Monroe County, off mangrove island SE of Cudjoe Key; 024°38'12"N, 081°18'12"W; 1 m; sta. FK-745; 15 May. 2005; R. Bieler, P. Mikkelsen leg.; FMNH 333533. • 11 valves; Florida Keys, Monroe County, quarry on Big Pine Key, in sediment on shoreline rock; 024°41'56"N, 081°23'03"W; sta. FK-728; 03 May. 2005; R. Bieler, P. Mikkelsen leg.; FMNH 333535. • 3 valves; Florida Keys, Monroe County, mosquito ditch on Big Pine Key; 024°42'30"N, 081°23'02"W; sta. FK-939; 25 Apr. 2010; R. Bieler, P. Mikkelsen leg.; FMNH 333532. • 3 valves; Florida Keys, Monroe County, Spanish Harbor Key; sta. JG-708-0; 08 Jun.2000; J. Gerber leg.; FMNH 308431. • 1 valve; Florida Keys, Monroe County, Ohio Key, land-locked pond adjacent to Ohio–Missouri Key bridge; 024°40'20"N, 081°14'36"W; sta. FK-723; 29 Apr. 2004; R. Bieler, P. Mikkelsen leg.; FMNH 314324. • 4 valves; Monroe County, Boca Chica Key; H. Hemphill leg.; ANSP 7983. Bahamas • 14 valves; Grand Bahama Island; 26°31'00"N, 78°46'30"W; J.N. Worsfold leg.; ANSP 374956. • 1 valve; Dover Sound, 26°35'05"N, 78°13'20"W, May.1983; J. N. Worsfold leg.; ANSP 374350. • 2 valves; 26°31'00"N, 78°46'30"W; J.N. Worsfold leg.; ANSP 374957. • 6 valves; Abaco; C.W. Johnson leg.; USNM 425821. • 2 valves; S side of Abaco; O. Bryant leg.; USNM 180503. Mexico • 10 valves (1 figured specimen); Quintana Roo, Boca de Paila; Tulane University leg.; UF 264025. • 20 valves; Tulane University; Emily & Harold Vokes leg.; UF 264026. GUATEMALA • 2 valves; Livingstone; 1913; A. A. Hinkley leg.; syntype; ANSP 107532.

Figures

Figures 1 - 10. Syntypes of Cyrenoida floridana and lectotype of C. guatemalensis. 1 - 4. Cyrenoida floridana (USNM 46846, length 12 mm, height 13 mm). 1. Left valve, external view; 2. Right valve, external view; 3. Left valve, internal view; 4. Right valve, internal view; 5 - 10. Cyrenoida guatemalensis (ANSP 107532; length 8.6 mm, height 8.9 mm). 5. Left valve, external view; 6. Right valve, external view; 7. Left valve, internal view; 8. Right valve, internal view; 9. Detail of left hinge; 10. Detail of right hinge. Scale bar: 2 mm.

Figures 11 - 24. Cyrenoida floridana, shell and gills details. 11 - 22, 23. UF 246126; 24. FMNH 328260. 11. Left valve, external view; 12. Right valve, external view; 13. Dorsal view of shell; 14. Anterior view of shell; 15. Posterior view of shell; 16. Left valve, internal view, muscle scars and pallial line outlined; 17. Right valve, internal view; 18. Left hinge, SEM; 19. Right hinge, SEM; 20. Internal surface of shell, SEM, showing microtubule orifices; 21. Detail of microtubule patch; 22. Fractured shell showing microtubules partially through shell thickness; 23. Detail of nodules at shell internal surface; 24. Gill fragment, transverse section, SEM. Scale bars: 1 mm (11 - 17, 23); 200 µm (18, 19); 20 µm (20 - 22), 0.5 mm (23); 10 µm (24).

Figures 25 - 34. Anatomy of Cyrenoida floridana (FMNH 328260). 25. Right view valve removed, some structures seen by transparency of mantle lobe; 26. Same, with mantle and gill removed; 27. Incurrent and excurrent siphons, posterolateral view, right mantle lobe partially removed, some adjacent structures shown; 28. Siphonal tips; right view, both partially sectioned longitudinally; 29. Mantle border, section in its ventromedial portion; 30. Gill, transverse section in its central portion; 31. Incurrent and excurrent siphons, interior view, with details of their base and siphonal muscles; 32. Labial palps, ventral view, outer hemipalps deflected dorsally; 33. Posteroventral visceral region, ventral view, showing fusion of inner demibranchs in siphonal base; 34. Pericardial region, posterodorsal view, dorsal mantle wall partially removed. Scale bars: 2 mm (25 - 28, 31, 33 - 34); 1 mm (29, 30, 32).

Figures 35 - 41. Anatomy of Cyrenoida floridana (FMNH 328260). 35. Digestive tubes as in situ; right lateral view; 36. Stomach, left lateral view; 37. Stomach, right lateral view, right wall opened and deflected to show inner gastric surface; 38. Cerebral ganglia, ventral view; 39. Visceral ganglia, ventral view; 40. Pedal ganglia; right figure in lateral right view, left figure in dorsal view; 41. Nervous system topology, right lateral view. Scale bars: 2 mm (35 - 41, 40); 0.5 mm (38 - 40).