FLEMINGER: INTEGUMENTAL ORGANS IN GENUS EUCALANUS 



Thn 



Thn 



ThEZ: 

 ThY 



Abd I-I 

 Abdin: 



Abd Ez:-::^ 



rh 2: 



Abd I-n 



^ Abd m 

 ° Abd 12-3: 



Figure ?. — Schematic presentation of all designated sites observed in adult female Eucalanus. Open-ended system for 

 designating individual sites provided by abbreviations of appendages or abdominal segments together with row (a, b. . . .) 

 and in dorsal view number to left or right of midline, or in lateral view number in dorsal to ventral order. 



Cephalosome in Eucalanus contains the cephalon extending from the first antennae (AI) to the second maxillae (Mx2), 

 the maxillipedal somite (Mxp = ThO) and the first pedigerous somite (ThI). Thoracic segments ThII. ThIII, ThIV bearing 

 swimming legs 2, 3, and 4 are separate from one another, but ThV lacking a pair of swimming legs in the female is partially 

 fused to ThIV. In the female abdomen the first two somites are fused (Abd.I-II) during maturation of the genital segment. 

 Abd.III is separate and Abd.IV is separate in the elongatus species group but fused to Abd.V in the other three species 

 groups. The furcal rami are fused to Abd.V in all the species. 



on each side, best seen in lateral view (Figure 

 6). Tergal sites on the cephalosome are pores 

 and peg sensilla; on ThII to ThV, all but two 

 (ThII-mb and Abd.IV-V-m) are hair sensilla; 

 the two exceptions are pores. The pleural sites 

 of the cephalosome appear to include both pores 

 and peg sensilla. Pleural sites on ThII to ThIV 

 are hair sensilla and those of the urosome are 

 pores. 



Within the genus four groupings may be dis- 

 tinguished by virtue of additional perforations 



that appear in common only among the species 

 comprising each group (Figure 8). Additional 

 support for these groupings may be found in 

 other morphological characters of taxonomic 

 value in Eucalanus such as segmentation of the 

 abdomen and the shape of the seminal recep- 

 tacles in females (Figure 1), fifth legs of adult 

 males, and various details in the appearance of 

 the cephalosome. The groupings and their 

 complement of species and geographical forms 

 are listed in Table 1. 



981 



