FLEMINGER: INTEGUMENTAL ORGANS IN GENUS EUCALANUS 



A 



tI mm 



B 



mm 



a 



Figure 11. — Species of the pilealus group of Encalanus: 

 a. pilealus, b. dcnuiius, c. \uhcni.\Mis. Dots represent 

 sites occurring at a frequency of lOO'yf in the pooled sam- 

 ple of the species; open circles are sites appearing in 80 to 

 99% of the pooled sample; crosses are sites occupied in 

 from 10 to 19'7c of the pooled sample. Open triangles are 

 sites also visible in lateral view but assigned to tergal sets. 

 Dorsal view above, lateral view below. All figures of adult 

 females made with the aid of a camera lucida. 



The Elongatus Group 



Species of the elongatus group are charac- 

 terized by 1 i)leural and 23 tergal sites in addi- 

 tion to the 37 and 9, respectively, present in the 

 genus (Figure 8a). The increase represents the 

 sum of one pair in the forehead (A2T-a-/l and 

 rl). two pairs on the maxillipedal somite (MxpT- 

 /3, /4 and r3, r4), two pairs on the first free thor- 

 acic segment (ThIT-/l, 12 and rl, r2). one medial 

 site each on ThIII, ThIV, and ThV, two dorsal 

 sites on the genital segment, and one additional 

 pleural site on each side of ThIV. 



E. inermia (Figure 13a) is distinguished in 

 dorsal view by the following tergal sites: a set 

 of eight on the Al somite, five on ThIV, three on 

 ThV, two on the genital segment, none on Abd.- 

 III and Abd.IV, and three on Abd.V. In lateral 

 view diagnostic pleural sites on either side in- 

 clude one on the genital segment and none on 

 Abd.IV. 



E. elongatus (Figure 13b) differs from each 

 of the other species in the group in a number of 

 details but only the two anterior tergal sites 

 on the second antennal somite (A2T-a-/l and 

 rl and the tendency for more than two sites on 

 Abd.III and Abd.IV are uniformly diagnostic 

 within the group. 



E. IiyaU)ius (Figure 13c). Single tergal sites 

 on ThI (ThIT-a-/l and rl) and the three tergal 

 sites on the genital segment distinguish Iiyaliuns 

 from the other species of the grouj). 



E. californicus (Figure 13d). Sites that dis- 

 tinguish caUfomicus from the preceding species 

 are the pair middorsal on the somite of the 

 second maxilla, the pair on the first free thora- 

 cic segment (ThIIT-a-/l, 12 and rl, r2), the 

 pair flanking the median site on Thll (ThllT- 

 b-/l, 12 and rl, r2), and in lateral view the three 

 pleural sites on either side of ThIV. No consis- 

 tent difference in number or in arrangement of 

 perforation sites was found that distinguishes 

 caUforiiicus from buugii. Both species are mor- 

 phologically distinctive in other respects (e.g., 

 setation of the mandibular basis) and share a 

 common boundary across the North Pacific, 

 calif ornicus occupying the temperate zone and 

 bungii occurring to the north, without any 

 apparent evidence of intergradation or hybrid- 

 ization. 



987 



