THE LIFE HISTORY OF THE SLOUGH DARTER, 

 ETHEOSTOMA GRACILE (PISCES, PERCIDAE) 



Marvin E. Braasch and Philip W. Smith 



SEVERAL STUDIES HAVE BEEN PUBLISHED 



on ieproducti\e habits of darters (for a summary, see 

 Winn 1958). However, a detailed life-history study 

 is not available for any of the eight species and sub- 

 species of the subgenus Hololcpis. The subgenus is an 

 ecologically distinctive group of which all members typi- 

 cally inhabit swamps, sloughs, and low-gradient streams 

 in the Coastal Plain and Mississippi River valley. 



A surprising amount of ecological information has, 

 nevertheless, been assembled by Hubbs & Cannon (1935) 

 and especially by Collette (1962) through remarkably 

 thorough reviews of others" published obser\ations and 

 through inferences drawn from morphology. This paper 

 on the slough darter, Etheostoma gracile (Girard), the 

 westernmost member of the subgenus, substantiates many 

 of CoUette's (1962) inferences and sup]3lies some miss- 

 ing details. 



Etheostoma gracile (cover illustration) is a rather 

 small darter; the adult normally ranges from 35 to 50 

 mm ( 1 ^2 - 2 inches) in total length. It shares with 

 other members of its subgenus a highly arched lateral 

 line. The species is unique throughout most of its range 

 in that the lateral line, consisting of 13-27 pored scales, 

 is within three to five scale rows of the base of the 

 spinous dorsal fin. 



Females, nonbreeding males, and large young ha\e 

 fine reticulations of brown on the back and sides, over- 

 laying a light yellow or tan. .\11 adult males and most 

 females and large young have green blotches or vertical 

 bands on the sides. In females, nonbreeding males, 

 and large juveniles the spinous dorsal fin is clear, ex- 

 cept for a subdistal red-orange stripe or row of red 

 dots; in breeding males the clear area becomes blue 

 black. The soft dorsal and caudal fins are barred with 

 brown; the paired fins and the anal fin are usually ])at- 

 ternless. 



During the breeding season the male differs from the 

 female in having brighter colors and dark ]iigment in 

 the basal portion of the s]jinous dorsal fin. Durintj all 

 seasons the male's genital ])ore is smaller tliati its anal 



]K)re, but in the female the genital pore is distinctly 

 larger than the anal pore. 



The small young of the species can be readily dis- 

 tinguished from juveniles of other darters occurring 

 with them by the distinctly reddish eye, three small 

 caudal spots, and pronounced upward flexure of the 

 groove for the lateral line. 



The species was described by Girard (1859:103) as 

 Boleosoma gracile (type-locality Rio Seco, Fort Inge, 

 Uvalde County, Texas) and, until Bailey (1951) re- 

 duced many nominal genera to subgeneric rank, was 

 variously placed in the genera Boleosoma, Bolcichthys, 

 Poccilichthys. and Hololepis. Poeciliclitliys butlerianus 

 Hay, 1882 (type-locality Big Black River, Yazoo County. 

 Mississippi) (1882:61) and Poeciliclitliys palustris G'il- 

 bert, 1884 (type-locality Switz City swamp. Greene 

 County, Indiana) (1884:209) are junior synonyms. 



However, most of the confusion in the literature 

 concerning Etheostoma gracile is the result of misidenti- 

 fication of specimens of the superficially similar and 

 allopatric E. e\ile (Girard) and of the closely related 

 and parapatric E. fusiformc (Girard) . A synomiTiy. 

 excellent descriptions, and analyses of individual and 

 geographic variation are gi\en by Collette (1962). 



The slou£;h darter occurs from the southern portion 

 of Illinois southward in the tributaries of the Wabash 

 and Mississippi rivers through western Kentucky and 

 Tennessee, the bootheel of Missouri, and the state of 

 Mississippi to the Gulf Coast: thence westward through 

 Louisiana and ."Arkansas ap])roximately to central Texas: 

 and north through eastern Oklahoma to southeastern 

 Kansas (Fig. 1). It is generally distributed and abun- 

 dant in the southern half of Illinois. 



A\'e arc indebted to Mark R. \Veher, Toshio Yama- 

 moto, l)a\id L. Thomas, .\rnold Gnilka, Dr. Max Hens- 

 lev, and Mrs. Dorothy M. Smith for aid in field work; 

 Dr. Hugh B. Cunningham, formerly of the Illinois Natu- 

 ral History Survey, for identification of insect fragments 

 during analyses of stomach contents; and Dr. Francis 

 j. Kruidenier. Uni\ersity of Illinois Department of 

 Zoology, for identification of a fluke parasite. We are 

 also grateful to Mrs. Alice Ann Prickett. formerly of 

 the Illinois Natural History Survey, for executing the 

 drawings and to Wilmer D. Zehr, Sur\-ev photographer, 

 for taking photographs of specimens and habitats. The 

 Illinois Natin-al Histoiy Sur\-ey provided laboratory fa- 

 cilities and subsidi7ed field work. The manuscript was 



COVER ILLUSTRATION: Adult male Efheosfomo gracile collected in late November In Johnson County, 

 Inols. From a watercolor by Mrs. Alice Ann Prickett. 



This paper is pulilisheti by authority of the State of Illinois. 

 IRS Ch. 127, Par. .')8.12, and is a contribution from the Section 

 of Fautii.stic Surveys and Insect Identification of tlie Illinois 

 Natural History Survey. It was submitted in its ori>?inal form 

 !)y Marvin K. Braasch in partial fulfillment of the retiuireinents 

 for the decree of Master of Science in the CSraduate College of 

 the ITniversity of Illinois. Mr. Braasch. a former technical 

 assistant at the Illinois Natural History Survey, is pi-esently at 

 the Museum of Natural Hi.story, University of Kansas. Lawrence. 

 Dr. Philip W. Smith is a taxonomist in the Section of Faunistic 

 Svu'veys and Insect T<lcntifica( ion. 



