142 Lawrence M. Page, Michael E. Retzer, Robert A. Stiles 



between the rock and substrate. One of us (RAS) has seen similar 

 behavior in E. maculatum in the upper Tennessee River system. The 

 clumping of eggs results not from the stacking of eggs on top of one 

 another, but because the eggs are pumped into the interface between the 

 slanted stone and stream substrate. When the stone is lifted from the 

 water, the adhesive clump (or at least part of it) is attached. 



Although most of the E. aquali eggs laid in the aquarium died, six 

 of a clump transferred to an aerated 600 ml glass dish hatched. Hatch- 

 ing time was three to four days at a fluctuating 24 to 28° C. Hatchlings 

 were 6.5 mm TL, had well-developed pectoral fins and jaws, and a 

 mid-dorsal series of bright gold flecks. 



Etheostoma (Nothonotus) microlepidum. — One nest of E. micro- 

 lepidum eggs and an attendant male, 53 mm SL, were found in a mod- 

 erately fast riffle in East Fork Stones River, Rutherford County, Ten- 

 nessee, on 6 May 1981. The riffle averaged 15 cm deep and was 

 composed of large gravel and small rubble; water temperature was 21° C. 

 The nest contained an estimated 346 eggs, averaging 2.0 mm in diame- 

 ter, arranged in a multi-layer clump essentially identical to those of E. 

 maculatum and E. aquali. 



Etheostoma maculatum, E. aquali, and E. microlepidum are closely 

 related, and we predicted that all would be egg-clumpers. Relationships 

 among other species of Nothonotus are less obvious, and it is difficult to 

 predict which clump eggs and which bury eggs. According to Zorach 

 (1972), other relatives of E. maculatum are Etheostoma acuticeps 

 Bailey, Etheostoma moorei Raney and Suttkus, and Etheostoma rubrum 

 Raney and Suttkus; confirmation of egg-clumping (the derived state) in 

 these species would confirm their recent shared ancestry with E. 

 maculatum. 



Although three unrelated subgenera (i.e. nonsister-groups) of dar- 

 ters amass and guard their eggs, the manner in which this is accom- 

 plished in Nothonotus is unlike that in Boleosoma and Catonotus. 

 Among North American freshwater fishes, single-layer clusters are laid 

 by Boleosoma, Catonotus, and the minnow genus Pimephales (McMil- 

 lan and Smith 1974); multi-layer clumps of eggs are laid by Nothonotus, 

 Noturus (madtoms) (Mayden and Burr 1981), and some Cottus (scul- 

 pins) (Smith 1922). The selective factors separating these two types of 

 behavior remain to be determined. 



ACKNOWLEDGMENTS. — We thank B. M. Burr, Southern Illi- 

 nois University at Carbondale, for helping search for nests of Etheos- 

 toma barbouri, and P. W. Smith, Illinois Natural History Survey, D. G. 

 Lindquist, University of North Carolina at Wilmington, and an ano- 

 nymous reviewer, for comments and suggestions on the manuscript. 



