FISHERY BULLETIN: VOL. 71, NO. 4 



8.0 



70 



6.0- 



50 



O bungii 

 9 californicus 

 © inermis 

 O hyalinus 

 © elongatus 



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90 100 no 120 



PERFORATION NUMBER 



130 



140 



Figure 14. — The elongatus group of Eucalanus. Perfora- 

 tion number plotted against total length (XL) in adult 

 .females comprising the pooled samples. 



phologically distinguished primarily by the 

 number and arrangement of integumental 

 organs and biogeographically by inferred dis- 

 tributions derived from the very different sets of 

 geographical localities available for each form. 

 In this regard it is important to stress that the 

 sampling localities were chosen to represent 

 the geographical extent of each population from 

 hundreds of localities of atte)n<atus s.l. obtained 

 during the course of global studies on several 

 calanoid genera. In the case of the two unusually 

 large species, parki and langae, the geographi- 

 cal records represent all that are on hand. A 

 major factor favoring separation of this complex 

 into four distinct species is the pattern seen in 

 the preceding three species groups and repeated 

 in the attenuatus group. That is, the species 

 with the broadest geographical range also shows 

 the most distinctive number or arrangement of 

 sites, especially on the genital segment, and 

 that related allopatric species may show little 

 or no difference in these features. 



In each instance the diagnosis is based on the 

 adult female and stresses those designated sites 

 characterizing the species within the group. 

 Thus despite the more formal presentation and 

 the addition of nonperforation data essential 

 to describe each species the information on num- 



990 



ber and arrangement of designated sites is 

 readily available within the diagnosis for each 

 species. 



Eucalanus attenuatus (Dana, 1849), 



sensu stricto 



(Figures Iq, 15d, 18a, g, j, k, n, q) 



E. attenuatus Dana, 1849, p. 18; 1853, p. 1080, 

 PI. 75, Figs. 2a-d; Vervoort, 1946, p. 95-103 

 (pars). Figs. 7a-c. 



E. pseudattenuatus Sewell, 1947, p. 39, Test fig. 

 7A. NEW SYNONYMY. 



Diagnosis: Adult female: Characterized by 

 having the largest number of designated sites 

 among the species of the attenuatus group (Fi- 

 gures 15d, 16; Tables 3, 4). Sites in addition 

 to those of the species group include two pairs of 

 tergal sites on ThIII (ThIIIT-b-/l, 12 and rl, 

 r2), two similar tergal pairs on ThIV, two ter- 

 gal sites on the genital segment, a single trans- 

 verse row of three tergal sites on Abd.IV-V 

 and, laterally, three pleural sites on either side 

 of Abd.IV-V (Figure 15d). Length of triangular 

 forehead extending beyond the lateral lobes 

 overlying the first antennae usually shorter] 

 than width at origin, apex acute in lateral view 

 and not curving ventrad (Figure 15d). Mandi- 

 bular basis with two setae. 



Adult male: Thoracic tergal sites as in female. 

 Abd.II with two tergal sites (Figure 18j). 

 Mandibular basis with two setae. Forehead 

 weakly produced beyond base of rostrum, apex 

 broadly rounded in dorsal and lateral views 

 (Figure 18g, k). 



Additional description: Female lacking fifth 

 pair of legs, abdomen with three separate seg- 

 ments (Figure 15d). Male left fifth legs with 

 four segments, right leg about half as long and^ 

 trimerous (Figure 18q). 



Total length: Adult female: range 3.63 to 

 4.65 mm, mean = 4.10 mm, s = 0.2900, A' = 2^ 

 (Figure 16). 



Adult male: range 2.93 to 3.50 mm, mean = 

 3.135 mm, s ^ 0.1775, N = 7. Specimens select- 

 ed at random from localities listed in Table 1. 



