PHYLOGENY OF ARIETELLID COPEPODS 



147 



Fig. 28. Paraugaptilus similis, female. SEM micrographs of genital double-somite. A, Genital double-somite, ventral view, copulatory pores 

 indicated by arrows, scale bar = 100 \xm\ B, Left gonopore, scale bar = 20 jj.m. 



and endopod fused to form flattened plate; basal setae of 

 almost equal length; endopod represented by plumose seta; 

 exopod completely absent. 



Male. Left antennule (Fig. 30C-E) 19-segmented; segments 

 IX to XV only partly fused near posterior margin; segments 

 XXI and XXII almost fused, but suture visible near anterior 

 margin; segments XXIV-XXV and XXVI-XXVIII incom- 

 pletely fused; fusion pattern and armature as follows: I-IV-7 

 + 4 aesthetascs (1-3 + aesthetasc, II — 1 + aesthetasc, III — 1 + 

 aesthetasc, IV-2 + aesthetasc), V-2 + aesthetasc, VI-2 + 

 aesthetasc, VII-2 + aesthetasc, VIII— 2 + aesthetasc, IX-2 + 

 aesthetasc, X-l + aesthetasc + process, XI-2 + aesthetasc, 

 XII-1 + aesthetasc + process, XIII— 1 + aesthetasc + pro- 

 cess, XIV-1 + aesthetasc + process, XV-1 + aesthetasc + 

 process, XVI-2 + aesthetasc, XVII-2 + aesthetasc, XVIII-2 

 + aesthetasc, XIX-1 + aesthetasc + 2 processes, XX-1 + 

 aesthetasc + process, XXI-XXIII-1 + aesthetasc + 3 pro- 

 cesses (XXI-aesthetasc + 2 processes, XXII-process, 

 XXIII-1), XXIV-XXVIII-11 + 2 aesthetascs + process (1 

 seta missing in Fig. 30E) (XXIV-1 + 1 + process, XXV-1 + 

 1 + aesthetasc, XXVI-XXVIII-7 + aesthetasc). Only first 

 segment fringed by short setules along posterior margin. 



Antenna: second endopod segment (Fig. 29G) approxi- 

 mately 1.3 times as long as first segment, with 1 long and 1 

 short seta medially; exopod (Fig. 29E,F) indistinctly 

 7-segmented, terminal compound segment bulbous (IX-X), 

 sixth (VIII) carrying long seta, seventh (IX-X) unarmed. 

 Mandibular palp (Fig. 29H): first exopod segment with long 

 seta. 



Leg 5 (Fig. 30F): coxae and intercoxal sclerite almost 

 completely fused; coxa and basis incompletely fused in right 

 leg, but separate in left; right and left endopods consisting of 



1 segment. Right exopod 2-segmented, ancestral second and 

 third segments almost completely fused, proximal segment 

 triangular, with short seta at outer angle, distal compound 

 segment lamellar, expanded proximally, tapering distally, 

 carrying short outer seta near base, triangular inner process 

 and 2 patches of setules medially. Left exopod indistinctly 

 3-segmented, first segment with short seta at outer angle, 

 second swollen inwards, bearing minute setule subterminally, 

 third segment incompletely fused with second segment, hav- 

 ing 2 processes, outer bifid at tip, and minute subterminal 

 outer setule. 



Remarks. The large process on segment XXIV of the left 

 antennule probably represents an extension of the cuticular 

 surface rather than a modified setation element. The anterior 

 subterminal process on the counterpart of the male left 

 antennule of Paraugaptiloides magnus is possibly homologous 

 to that of Paraugaptilus. The presence of 2 aesthetascs 

 located immediately adjacent to each other on the extreme 

 tip of the left antennule is interpreted here as an abnormality. 



Paraugaptilus buchani Wolfenden, 1904 (Figs 31,32) 



Material examined. $ and cf ■ 



Body length. $ 3.14 mm; cf 3.25 mm. 



Description. Female. Cephalosome separate from first 

 pedigerous somite. Genital double-somite (Fig. 31A) similar 

 to that of P. similis, but relatively shorter, left copulatory 

 pore located near posterior margin. Female left antennule 

 (Fig. 32A) with same fusion pattern and armature as in 

 female P. similis except for following: segment XXIII incom- 



