FLEMINGER: INTEGUMENTAL ORGANS IN GENUS EVCALANUS 



ThIT-a-/4^ -/l- -a-rl- -r4 



-/I -mb -rl -r57 



\ / y • • / 



Th 11-0-/3 -Zr -mb -rl -r3 



ThIT-b-/5 



•/I 



0' 



©• ® •© 



ThnT-b-/2 



-r2 



ThIP-rb-1 



iThUP-ra-l^ ^-ra-2| 

 ThUP-rb-l- -rb-4 



Figure 7. — Scheme for codifying designated sites in Eiicalaiins. Left: dorsal view of posterior portion of cephalosome 

 and thoracic segment 2. Right: hiteral view of same. 



First unit of code for referring to a designated site is reference to the somite, using the appropriate appendage in the 



case of the cephalosome or the body segment (ThII. ThIII Abd.I-II, Abd.III, . . .). Second unit indicates whether 



it is dorsal, i.e., tergal (T), or lateral, i.e.. pleural (P). Tergal sets are grouped in transverse rows. Thus, perforations 

 are designated as being on the right (r) or left (1) of the mid-sagittal plane and are numbered from the medialmost to the 

 lateralmost (1. 2, . . .). Transverse rows are lettered in an anterior-to-posterior sequence (a, b, . . .). Perforations falling 

 on the midsagittal plane are termed medial (m) and lettered in an anterior-to-posterior sequence (a, b. . . .). 



Benh right (r) and left (1) laterial. i.e.. pleural (P), sets are numbered in a dorsal-to-ventral sequence (1, 2. . . .). For 

 convenience anterior-to-posterior division into rows is utilized following the corresponding set of tergal sites and are 

 also lettered in an anterior-to-posterior sequence. 



Various sites in dorsal and lateral views in the figures are codified according to the scheme proposed above. 



the tagma also showing the most extensive 

 geographical variation. Geographical variation 

 in subtenuis distinguishing the Indian, Atlantic, 

 and East Pacific populations is discussed below 

 (p. 999). The other four species fall within a 

 narrow overlapping range ( > 80 to < 95 perfora- 

 tions). Differences in number and arrangement 

 especially in the genital segment characterize 

 crassus and mucro)iatHS, the two species over- 

 lapping geographically in the Indian and West 

 Pacific Oceans. Differences in number and pat- 

 tern also involving the genital segment distin- 

 guish crassus and monachus which co-occur in 

 the Atlantic Ocean. E. craHSUs also differs 

 from Io)igiceps, a temperate species of the 

 Southern Hemisphere, and from sKbtcnuis 

 in the sites on the genital segment. 



The Pileatus Group 



The pileatus group (Figure 8d) consists of 

 three sibling species that are only weakly dif- 

 ferentiated in general appearance from that of 

 the subtenuis group. The pileatus group also 



strongly resembles the subtenuis group in per- 

 foration pattern, the primary differences being 

 in a small increase in the number of middorsal 

 sites on the thoracic segments. One additional 

 pair occurs on the somite of the first maxilla, 

 and single anterior middorsal sites are found 

 on ThIII and ThIV. Three tergal sites may 

 appear on the genital segment, but the posterior 

 two of the three sites are irregular in occurrence 

 in pileatus; therefore, at the species group level, 

 the genital segment is best characterized by a 

 single middorsal site. 



Among the individual species E. pileatus 

 is essentially undifferentiated from the pattern 

 in the species group (Figure 11a). It lacks ter- 

 gal sites on the somite of the second maxilla and 

 on Abd. Ill, although it has three tergal sites 

 across Abd.IV-V. It also lacks posterodorsal 

 pleural sites on ThI. ThII, and ThIII. The geni- 

 tal segment may have one or two posterotergal 

 sites in addition to the regular middorsal site. 



E. (h'litatus and suboxtssus share a number of 

 features that separate them from pileatus, name- 

 ly two tergal pairs of sites on the somite of the 



983 



