FISHERY BULLETIN: VOL. 72. NO. 1 



10- 







20- 



10- 







>20 



■z. 



UJ 



O 10 



UJ 



0^ 



4oL 



20 

 10 







J L 





platychela 

 x= 2.3100 

 s=.30l8 

 N = 49 



J I 



J I 



morn 



x= 1.4555 



s = .l5ll 



N = 55 



\ \ I 



\ ^ 



I I I I I 



sobrina 



x = l.2827 



s=.0904 



N = 52 



I I I I 



1.0 



14 



P5 



1.8 2.2 



Re 



Ri 



2.6 3.0 



.9 



Figure 29. — Frequency distribution of P5 Re:Ri ratio for 

 females of the four species of Pontellina. 



evidence it ))rovides in support of our judgment 

 that the four siblings are valid species recently 

 derived from the same parent species. The 

 frequencies and vv^idespread geographical 

 occurrence of phenotypes are evidence of simple 

 Mendelian inheritance and indicative of balanced 

 polymorphism. Another pontellid, Labklocera 

 diandra, has also been shown to be polymorphic 

 (Fleminger, 1967b). In both Pontellina and 

 Labidocem the apparent polymorphism affects 

 a sexually modified appendage before the onset 



of maturity, the phenotypes being distinguish- 

 able in copepodite stage V. However, within 

 its species group, only L. diandra displays the 

 polymorphism which is visible in the male sex. 



Male Fifth Legs and Right First Antenna 



Segment lengths of sexually modified appen- 

 dages that we examined tend to vary directly 

 with prosome length. We chose the length of 

 the right furcal ramus (Figure 25) instead of 

 the prosome as our standard body length 

 reference for comparing morphometry of 

 sexual appendages because the furcal ramus 

 length yielded graphic presentations with con- 

 siderably less scatter within each sample. 



.20 



E 



e 



< 



< 

 O 



3 



1- 

 X 



^ .14 



o 



o 



.10 



   



2-* #-2 a 



4 i-s^-z 2-n n-3 



2-* ^^♦f ♦-S 

   



 



D D 



^-2 ''i 



no D 



/2 /2 



n D D 



A 



• • 



 plumata 



• morii 



A sobrina 

 D platychela 



Va 



• -^'^A •' A 



A A^ A-3 



A- 4 



_L 



J 



08 ,10 .12 -14 .16 



LENGTH OF LEFT P5 Re1, mm 



Figure 30. — Length of right furcal ramus (ordinate) plot- 

 ted against length of left P5 Rel (abscissa) for males of the 

 four species of Pontellina. 



Table 7. — Frequencies (%) of phenotypes varying in the number of spines on the 

 endopod of the fifth pair of swimming legs in Pontellina spp. females. 



Species (/V) 



Left leg: 

 Right leg: 



I spine 

 1 spine 



1 spine 

 2 spines 



2 spines 

 1 spine 



2 spines 

 2 spines 



plulychela (100) 

 pluinuia (300) 

 morii (200) 

 sobrina (100) 



98 



