Lasmigona costata (Rafinesque 1820) Flutedshell (ASUMZ 1982, length 77.7 mm. South Fork Spring River ca. 0.7 river km upstream of Co. Rd. 80 and ca. 1.0 rd km E of Sturkie, Fulton County, Arkansas.) 1 KEY CHARACTERISTICS: Shell shape rayless in old individuals. The nacre is rectangular to rhomboid, elongated, solid, white, with considerable variation in the and somewhat compressed; anterior end amount of cream or salmon present; the area rather sharply rounded, posterior end between the pallial line and margin obliquely truncated. The posterior ridge is iridescent Mature individuals may attain a usually well-developed; rounded plications length of 190–200 mm.. The animal is dark (also referred to as flutes or corrugations) to pale orange. are usually present and directed outward from the posterior ridge toward the posterior DISTRIBUTION: Entire Mississippi River and dorsal shell margins. Some Ouachita basin from western New York and Mountains drainage populations in Arkansas Pennsylvania west to western Iowa, eastern and Oklahoma have greatly reduced or Kansas, and eastern Oklahoma; Wisconsin entirely lack posterior ridge and slope and southern Minnesota south to southern plications. Populations of this morphotype in Arkansas, Alabama, and Mississippi; the upper Chippewa River of Wisconsin also Hudson Bay basin in the Red and Winnipeg lack posterior plications, and Baker (1928) River drainages, and in the Great Lakes-St. erected the (currently unrecognized) Lawrence basin from southern Lake Huron subspecies Lasmigona costata nuda for the and its tributaries to the Ottawa River and form. The shell disc anterior of the posterior Lake Champlain (Clarke 1985, Vidrine ridge sometimes has plications or weak, 1993, Howells et al. 1996, Parmalee and irregular wrinkles. The disc may also have Bogan 1998, Williams et al. 2008, Watters growth rest periods indicated by heavy, et al. 2009). prominent concentric ridges edged with black. Umbo is depressed and flattened; DISRIBUTION MAP: Lasmigona costata umbo sculpture consists of 3–4 strongly developed, heavy bars, parallel with the Records used for the distribution map are hinge line. The first is simply curved, while from: Illinois Natural History Survey the others are more or less double-looped. (IHNS); North Carolina State Museum of The left valve has a single heavy, curved, Natural Sciences (NCSM); Ohio State pyramidal, elevated pseudocardinal tooth University Museum of Biodiversity that is actually two teeth fused into one. The (OSUM); University of Florida Museum of right valve has a heavy, low, somewhat Natural History (UF). elongated pseudocardinal tooth. Lateral teeth in both valves are reduced to SIMILAR SPECIES: Lasmigona costata thickenings of the hinge line that may superficially resembles Ptychobranchus appear as irregular ridges or may be totally subtentus (Fluted Kidneyshell) but P. absent. The interdentum is narrow or absent. subtentus shell sculpture is restricted to the The interdental projection in the left valve is posterior ridge and slope whereas L. costata well-developed and may appear fused with typically has sculpture over the posterior 25- the posterior pseudocardinal tooth, and it fits 50% of the shell (Williams et al. 2008). into a depression in the right valve posterior Lasmigona costata has rudimentary lateral to the pseudocardinal tooth. The umbo teeth, but those of P. subtentus are well- cavity is very shallow. The periostracum is developed. Lasmigona complanata (White yellowish with numerous green rays in Heelsplitter) also has plications on the young shells; mature shells are a darker posterior slope and lacks lateral dentition, yellow or brown, becoming black and but it is much rounder in outline, usually 2 with a distinct posterior wing (Watters, et al. glochidial hosts spanning a broad array of 2009). Lasmigona compressa (Creek freshwater fish families including Amiidae: Heelsplitter) lacks corrugations, has a Bowfin (Amia calva); Anguillidae: tongue-like structure on the left valve hinge American Eel (Anguilla rostrata); interdentum, and has lateral teeth (Watters et Clupeidae: Gizzard Shad (Dorosoma al. 2009). Lasmigona costata populations cepedianum); Cyprinidae: Central with reduced shell sculpturing may resemble Stoneroller (Campostoma anomalum), Alasmidonta marginata (Elktoe), Strophitus Goldfish (Carassius auratus), Common undulatus (Creeper), and Uniomerus Carp (Cyprinus carpio), Whitetail Shiner tetralasmus (Pondhorn). Alasmidonta (Cyprinella galactura), Spotfin Shiner (C. marginata is relatively more inflated and has spiloptera), Steelcolor Shiner (C. whipplei), a more sharply angled posterior ridge with Brassy Minnow (Hybognathus hankinsoni), much finer plications (sculpturing) than L. Common Shiner (Luxilus cornutus), costata. Strophitus undulatus is relatively Hornyhead Chub (Nocomis biguttatus), more inflated, has a centrally positioned and Golden Shiner (Notemigonus crysoleucas), broader umbo, a bluntly pointed posterior Spottail Shiner (Notropis hudsonius), Mimic end, and the lateral and pseudocardinal teeth Shiner (N. volucellus), Southern Redbelly are reduced with a slightly sinuous hinge Dace (Phoxinus erythrogaster), Bluntnose line. Uniomerus tetralasmas has a bluntly Minnow (Pimephales notatus), Longnose pointed posterior end and thin but well- Dace (Rhinichthys cataractae), Creek Chub developed lateral and pseudocardinal teeth. (Semotilus atromaculatus); Catostomidae: White Sucker (Catostomus commersoni), HABITAT: Medium-sized rivers to large Northern Hogsucker (Hypentelium creeks with moderately strong current and nigricans), Bigmouth Buffalo (Ictiobus substrate composed of coarse sand and cyprinellus), River Redhorse (Moxostoma gravel provide the most suitable habitat. In carinatum), Shorthead Redhorse (M. such rivers it is found typically at depths of macrolepidotum); Ictaluridae: Black one meter or less. Lasmigona costata occurs Bullhead (Ameiurus melas), Yellow less commonly in large lakes and rivers (i.e., Bullhead (A. natalis), Brown Bullhead (A. Lake Erie, Mississippi River). nebulosus), Channel Catfish (Ictalurus punctatus); Esocidae: Northern Pike (Esox BIOLOGY: Long term brooder lucius); Fundulidae: Northern Studfish (bradytictic), the reproductive period (Fundulus catenatus), Blackspotted beginning in August with glochidia carried Topminnow (F. olivaceus); Poeciliidae: until May (Baker 1928). Two types of Mosquitofish (Gambusia affinis), Mexican glochidia reported: first triangular and Molly (Poecilia sphenops); Cottidae: strongly hooked; second round, weakly Banded Sculpin (Cottus carolinae); hooked or unhooked with shell grown in Centrarchidae: Rockbass (Ambloplites marsupium (Watters et al. 2009). It is rupestris), Green Sunfish (Lepomis possible that Lasmigona costata may be cyanellus), Green Sunfish/Pumpkinseed facultative parasites able to forego the hybrid (L. cyanellus X L. gibbosus), parasitic stage (Watters et al. 2009), and that Pumpkinseed (L. gibbosus), Orangespotted the second glochidial type reflects direct Sunfish (L. humilis), Bluegill (L. development. Glochidia are held in the outer macrochirus), Longear Sunfish (L. gills and released as a loose mass (Leonard megalotis), Redear Sunfish (L. et al. 2014). A host generalist with reported microlophus), Smallmouth Bass 3 (Micropterus dolomieu), Largemouth Bass (M. salmoides), Black Crappie (Pomoxis nigromaculatus); Percidae: Rainbow Darter (Etheostoma caeruleum), Fantail Darter (E. flabellare), Striped Darter (E. virgatum), Banded Darter (E. zonale), Yellow Perch (Perca flavescens), and Walleye (Sander vitreus); (LeFevre and Curtis 1910 and 1912, Fuller 1978, Luo 1993, Weiss and Layzer 1995, Hove et al. 1994, Watters, et al. 1998, Watters et al. 1998, Watters et al. 2005, Thompson et al. 2013, Leonard et al. 2014.). NORTH AMERICAN CONSERVATION STATUS: Currently Stable (Williams et al. In preparation). ORIGINAL DESCRIPTION: Alasmidonta costata Rafinesque 1820; Rafinesque, 1820: 318, pl. 82, figs. 15, 16. TYPE LOCALITY: Kentucky River. SYSTEMATICS: Placed in the nominal subgenus Lasmigona with L. complanata and L. alabamensis (Clarke 1985). There are currently no broad-scale phylogenetic or phylogeographic analyses for L. costata. Compilers: J.L. Harris, Department of Biological Sciences, Arkansas State University, State University, AR 72467 [email protected], A.E. Bogan, North Carolina State Museum of Natural Sciences, Raleigh, NC 27601, [email protected]. 4 Parmalee, P.W. and A.E. Bogan. 1998. The References: freshwater mussels of Tennessee. The University of Tennessee Press, Knoxville, Baker, F.C. 1928. The freshwater Mollusca of Tennessee. 328 pages. Wisconsin. Part II. Pelecypoda. Bulletin of Rafinesque, C.S. 1820. Monographie des coquilles the Wisconsin Geological and Natural bivalves fluviatiles de la Riviere Ohio, History Survey. University of Wisconsin. contenant douze genres et soixante-huit 70(2):i-vi + 495 pages. especes. Annales Générales des Sciences Clarke, A.H. 1985. The tribe Alasmidontini Physiques 5 (5): 287-322 + plates 80-82. (Unionidae: Anodontinae), Part II: Thomason, J., M. Hove, B. Sietman, M. Berg, S. Lasmigona and Simpsonaias. Smithsonian Anderson, S. Bump, A. Lindeman, N. Ward, Contributions to Zoology, 399. 75 pages. S. Morley, S. Berreth-Doran, and C. Fuller, S.L.H. 1978. Fresh-water mussels (Mollusca: Poeschl. 2013. Laboratory trials show Bivalvia: Unionidae) of the Upper Flutedshell (Lasmigona costata) transform Mississippi River: Observations at selected on several fishes. Ellipsaria 15(2):19-21. sites