Upper labial extension very elongate, straight to weakly curved medially and nearly uniform in width with a bluntly rounded tip. Differs further from all Leptodoras except L. acipenserinus by having an adipose fin extending anteriorly as a low thin ridge to a point midway between the anterior insertion of the adipose fin and the posterior insertion of the dorsal fin. Distinguished from L. acipenserinus by a number of characters including a relatively longer predorsal distance (35.5-38.7% SL), inner flap of gill opening incomplete, lower sum of midlateral plates (74-81), anal-fin shape (tip of longest branched ray falls short of vertical through tip of last branched ray in extended anal fin and is more or less even with vertical through base of last ray; line defined by tips angled anteriorly, forming a 45-90° angle with long axis of body), pectoral-fin spine length 19.9-26.2% of SL and pectoral-fin spine dentation with teeth strongly retrorse along majority of posterior margin, becoming less retrorse distally, size relatively uniform along distal half, last denticulation usually subterminal (Ref. 56896).