Ichthyomyzon gagei Hubbs & Trautman, 1937
Southern brook lamprey
photo by The Native Fish Conservancy

Family:  Petromyzontidae (Northern lampreys), subfamily: Petromyzontinae
Max. size:  17 cm TL (male/unsexed)
Environment:  demersal; freshwater
Distribution:  North America: Mississippi River basins, Tennessee River drainage and Gulf of Mexico Coast drainages from Ochlockonee River in Florida to Galveston Bay in Texas, USA.
Diagnosis:  Distinguished by the following characters: Oral disc narrower than head; teeth blunt and poorly developed; usually 52-56 trunk myomeres; black on lateral-line pores; one slightly notch dorsal fin (Ref. 86798). Other adult diagnostic features: 8.6-12.9 cm TL. Body proportions, as percentage of TL (based on 35 specimens measuring 8.6-12.9 cm TL): prebranchial length, 8.3-11.2; branchial length, 8.3-11.1; trunk length, 47.0-56.0; tail length, 25.6-33.3; eye length, 1.1-2.1; disc length, 3.8-6.5. Urogenital papilla length, as a percentage of branchial length, in 6 spawning males measuring 9.2-11.1 cm TL, 22.7-33.3. Trunk myomeres, 50-56, with a strong mode at 53. Dentition: supraoral lamina, 2-4 teeth, usually 2; infraoral lamina, 5-10 unicuspid teeth, usually 8-9; 4-5 endolaterals on each side; 0-8 bicuspid endolaterals in total, the other endolaterals, unicuspid; 3-4 rows of anterials; first row of anterials, 3 unicuspid teeth; 3-4 rows of exolaterals on each side; 2 rows of posterials; first row of posterials, 9 unicuspid teeth; crest of transverse lingual lamina linear to weakly w-shaped, with no apparent cusps; longitudinal lingual laminae each with undetermined number of unicuspid teeth. Velar tentacle number unrecorded. Body coloration (preserved) distinctly bicolored, with the dorsal aspect dark and the ventral aspect light. Lateral line neuromasts darkly pigmented. Caudal fin pigmentation unrecorded. Caudal fin shape, rounded. Oral fimbriae number unrecorded. Oral papillae number unrecorded (Ref. 89241).
Biology:  Freshwater (Ref. 89241). Inhabits gravel and sand riffles, and runs of creeks and small rivers. Ammocoete larvae occur in flowing water near sand bars and debris. Non-parasitic (Ref. 5723). Average fecundities varied from 713-2,448 eggs/female among 19 localities across the distributional range (Ref. 89241).
IUCN Red List Status: Least Concern (LC); Date assessed: 17 February 2012 Ref. (130435)
Threat to humans:  harmless


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