Macrobrachium ohione (Smith) 



Figure 45 



Palaemon Ohionis Smith, 1874, p. 640. 



Macrobrachium ohione: Holthuis, 1952, p. 62, pi. 14, fig. 

 b (rev.). 



Recognition characters. — Rostrum high and 

 straight, tip curving somewhat upward and reach- 

 ing to between end of antennular peduncle and 

 end of antennal scale; upper margin with 9 to 13 

 teeth, 3 or 4 teeth behind orbit, first 3 more widely 

 separated than remainder; lower margin with 1 

 to 3 teeth; distal two-fifths of rostrum unarmed. 

 Carapace smooth; antennal spine slightly remote 

 from anterior margin; hepatic spine below an- 

 tennal spine. Antennal scale about 2.5 times 

 longer than broad; outer margin straight or 

 slightly concave. 



First legs with chelae reaching beyond scale; 

 chelae slender; fingers about as long as palm; 

 carpus twice length of chela. Second legs in adult 

 female stronger than in male, with carpus and 

 chela reaching beyond scale; fingers somewhat 

 shorter than palm, cutting edges pubescent and 



with four to eight small denticles of equal size 

 on proximal half, remainder of surface with scat- 

 tered hairs; palm elongate, cylindrical, entirely 

 pubescent, most conspicuous pubescence along 

 lower surface; carpus, merus, and palm of equal 

 length, these articles and fingers with longitudinal 

 rows of small spinules; carpus most pubescent 

 anteroventrally; merus somewhat pubescent an- 

 teroventrally. 



Abdomen smooth ; pleura of fifth segment end- 

 ing in acute point. Telson about 1.5 times length 

 of sixth segment; pairs of dorsal spines at mid- 

 dle and three- fourths of length; posterior margin 

 ending in an acute tip overreached by inner pair 

 of posterior spines. 



Measurements. — Length of body : male, 68 mm. ; 

 female, 102 mm. 



Variations. — Juveniles (10 mm. and larger) 

 have the same number of rostral spines as adults 

 but fewer spines behind the orbit. In such 

 juveniles, the hepatic spine is very close to the 

 anterior margin of the carapace, similar in posi- 

 tion to a branchiostegal spine. 



Figure 45. Macrobrachium ohione (Smith). A, animal in lateral view (after Hedgpeth, 1!M9) ; B. second leg 



of adult male (after Holthuis, 1!>T>2). 



54 



FISH AND WILDLIFE SERVICE 



