FLEMINGER and HULSEMANN: FOUR SIBLING SPECIES OF PONTELLINA 



l-5r 



1.4 



E 13 



E 



o 



IS) 



o 

 tr 



CL 



 p/umafa 



• morii 



A sobrina 

 □ platychela 



.2 



o 



X 



I- 



UJ 



I.I 



1.0 



09 



A ^ 



A 



J L 



12 14 16 18 .20 



LENGTH OF RIGHT FURCAL RAMUS, mm 



Figure 26. — Length of P (ordinate) plotted against length 

 of right furcal ramus (abscissa) for males of the four species 

 of Pontellina. 



may be borne on a weakly produced boss; morii 

 and sobrina bear a small spine resembling that 

 found in the female of the species; platychela 

 has no outgrowth whatsoever. 



WIDTH ---".- .^-......o 



Figure 27. — Length of P (ordinate) plotted against length: 

 width ratio of right furcal ramus (abscissa) for females of 

 the four species of Pontellina. 



o 



CO 



o 

 tr 

 a. 



1.40 



120 



plunnata Pacific - Indian 

 'i plumata Atlantic 



- • morii 

 A sobrina ^ 



- a platyctiela 



O 1.00 



^ 



D 



D 



n 



A 2- 



. AAjg *" • 



-^ 



2 •-a . D 



A ^^^ 





A 



A 



1.60 



180 2.00 



LENGTH 



220 



240 

 RIGHT FURCAL RAMUS 



260 



WIDTH 



Figure 28. — Length of P (ordinate) plotted against length: 

 width ratio of right furcal ramus (abscissa) for males of the 

 four species of Pontellina. 



Female Genital Segment 



The distribution of lateral clusters of spinules 

 provides the basis for distinguishing the different 

 character states. Two species, sobrina and 

 plumata, are similar in having two clusters on 

 each side; morii has one cluster and platychela 

 has none. There is preliminary evidence from 

 examination with the scanning electron micro- 

 scope (SEM), however, that the similarity of 

 plumata with sobrina may in fact be superficial. 

 Cluster size and spinule size differ even under 

 the light microscope, and the SEM indicates 

 the presence of fine sensoriiform filaments in 

 sobrina and morii, but not in plumata or platy- 

 chela. The SEM also revealed a second cluster 

 consisting of minute denticles in morii anterior 

 to the one visible with the aid of a light micro- 

 scope (in preparation). 



Female Fifth Pair of Swimming Legs 



The two characters found in P5 that provide 

 diagnostic information, i.e., the Re:Ri length 

 ratio (Figure 29) and the distribution of spines 

 on the endopod (Table 7) agree in showing 

 strong similarity between morii and sobrina 

 on the one hand and between platychela and 

 plumata (all geographical sectors combined) 

 on the other. It should be noted, however, that 

 the similarity between platychela and plumata 

 is weakened when the comparison is restricted 

 to Atlantic Ocean samples of plumata (in 

 preparation). 



The distribution of the spines on the endopod 

 is also noteworthy by virtue of the compelling 



97 



