FLEMINGER: INTEGUMENTAL ORGANS IN GENUS EUCALANUS 



20° 0° 20' 



100° .— --I— 



Figure 17. — Geographical localities of the species in the attenuatus group. All identifications except those of Park 



( 1968) and Bradford (1970) verified by examination of integumental organs. 



Diag)iosis: Adult female with mandibular 

 basis bearing two setae as in atteituatus. Differs 

 from attenuatus in designated sites on ThIII 

 and ThIV, each of which lacks the two pairs of 

 tergal sites enclosed by the outer arc of six 

 tergal sites (Figure 15c). Genital segment lack- 

 ing integumental organs. Abd.IV-V with two 

 transverse tergal rows and lacking pleural 

 sites (Figure 15c). 



Adult male: Tergal sites on ThIII and ThIV 

 as in female. Abd.II lacking dorsal integumental 

 organs (Figure 18i). Mandibular basis with two 

 setae. 



Additional descri'ption: Adult female with 

 forehead more strongly attenuated and longer 

 than that in attenuatus (Figure 15c). apex 

 usually curving weakly ventrad (Figure 18c). 

 In relatively eutrophic regions of the Indo- 

 Pacific attenuatus and seivelli may co-occur and 



resemble one another in size and general mor- 

 phology, but differences in integumental organs 

 persist. In strongly eutrophic tropical regions 

 sewelli may exceed 6 mm in TL and exhibit 

 a more prominent conical forehead with rounded 

 apex (Figure 18d). Male with fifth pair of legs 

 as in attenuatus (Figure 18o, r). 



Total length: Adult female: range 3.89 to 

 6.10 mm. mean = 4.720 mm. .s- - 0.6350. 

 A' = 43 (Figure 16). 



Adult male: range 2.89 to 4.58 mm. mean = 

 3.195 mm, .s- = 0.4680. A' = 14. Specimens 

 selected at random from localities listed in 

 Table 1. 



Geographical distribution: Verified localities 

 (Figure 17) indicate a circumglobal range in 

 eutrophic tropical and subtropical waters ex- 

 tending to the subtropical convergences. 



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