PHYLOGENY OF ARIETELLID COPEPODS 



123 



II each with 1 seta; segment XIII with seta and process; 

 segment XXI fused with XXII; compound segment 

 XXIV-XXV with large cuticular process; compound segment 

 XXVI-XXVIII with 8 setae and aesthetasc. Antenna: first 

 endopod segment without inner seta, second segment with 2 

 inner setae at midlength and 5 setae and 1 setule terminally; 

 exopod indistinctly 8-segmented, setal formula 

 0,1,1,1,1,1,0,3. Mandibular palp: endopod rudimentary, 

 1-segmented, with 2 setae; seta on first exopod segment not 

 reduced; outer seta on fifth exopod segment relatively long. 



Maxillule: praecoxal arthrite with 5 spines and 1 process; 

 coxal endite carrying long seta; coxal epipodite bearing 8 

 setae; no basal seta; endopod 1-segmented, bearing 2 setae. 

 Maxilla: first praecoxal endite with 2 setae and 1 vestigial 

 element; second praecoxal endite with 2 setae; basal spine 

 with 2 rows of spinules. Maxilliped: endopodal setal formula 

 1,4,4,3,3,4; innermost seta on fourth and fifth endopod 

 segments not vestigial; seta a on sixth endopod segment 

 reduced, seta b relatively long. 



Leg 1 with 2 outer spines on third exopod segment. Leg 4 

 with vestigial element on inner distal corner of coxa. Leg 5: 

 coxae fused with intercoxal sclerite; basis and coxa separate 

 in left leg and incompletely fused in right. Right leg: endopod 

 1-segmented, rudimentary, unarmed; second exopod seg- 

 ment expanded inwards, almost completely separate from 

 third segment, third segment triangular, tapering distally, 

 with 1 minute outer and 1 terminal setules. Left leg: endopod 

 2-segmented, unarmed; exopod 3-segmented, distal 2 seg- 

 ments completely separate, second segment expanded 

 inwards, third segment with 2 long stout processes directed 

 laterally. 



Type species. Paraugaptilus tnagnus Bradford, 1974 (mono- 

 typic). 



Remarks. Bradford (1974) assigned a male collected from a 

 depth of 1697 m off the north-east coast of North Island, New 

 Zealand, to the genus Paraugaptilus, although she mentioned 

 seven distinct characters of the species that would possibly 

 necessitate its removal to a new genus. Morphological discon- 

 tinuities can be found between P. tnagnus and other species 

 of Paraugaptilus as follows: (1) left antennulary compound 

 segment XXVI-XXVIII with 8 setae and aesthetasc; (2) 

 antennary exopod indistinctly 8-segmented, with setal for- 

 mula 0,1,1,1,1,1,0,3; (3) mandibular endopod almost fused 

 with basis, but represented by a rudimentary segment with 2 

 setae; (4) maxillule with long seta on coxal endite, 1 basal 

 seta and 2 setae on 1-segmented endopod; (5) maxilla with 2 

 setae and 1 vestigial element on first praecoxal endite and 2 

 setae on second; (6) setae on maxillary endopod ornamented 

 with row of simple spinules along inner margin but lacking 

 triangular-shaped ornamentation found in other species of 

 Paraugaptilus; (7) seta b on sixth endopod segment of maxil- 

 liped not reduced; (8) second and third exopod segments of 

 right leg 5 almost completely separate; (9) leg 5 with 

 2-segmented left endopod. 



In genera accommodating several species, such as Parami- 

 sophria, Arietellus and Metacalanus, the praecoxal arthrite, 

 coxal endite and endopod of maxillule, first praecoxal endite 

 of maxilla, and leg 5 exhibit wide interspecific variation in 

 armature. However, the armature of the antennary exopod, 

 mandibular palp, second praecoxal endite of maxilla, endo- 

 pods of male leg 5 are relatively consistent within each genus. 

 In particular, the significant differences found in the anten- 



nary exopod, the mandibular endopod and the second prae- 

 coxal endite of the maxilla support the proposal to assign P. 

 magnus to a new genus, Paraugaptiloides. 



The new genus is similar to Arietellus and Paramisophria in 

 the segmentation and setation of appendages, but can be 

 distinguished from these genera by: (1) the presence of a 

 large cuticular process on left antennulary segments 

 XXIV-XXV (shared with Paraugaptilus); (2) the lack of a 

 seta on the first endopod segment of antenna, also absent in 

 Arietellus but present in Paramisophria; (3) the 2 inner 

 medial setae on the second endopodal segment of antenna in 

 Paraugaptiloides and Arietellus, compared to 3 in Parami- 

 sophria; (4) outer seta on fifth exopodal segment of mandible 

 relatively long in Paraugaptiloides and Paramisophria, but 

 vestigial in Arietellus; (5) mandibular endopod 1-segmented 

 with 2 setae in Paraugaptiloides and Paramisophria, but 

 absent in Arietellus; (6) maxillule with 1 basal and 2 endopo- 

 dal setae in Paraugaptiloides and Paramisophria, but no basal 

 and, at most, single endopodal seta in Arietellus; (7) maxil- 

 lary basal spine ornamented with spinules in Paraugaptiloides 

 and Arietellus, but no ornamentation in Paramisophria; (8) 

 innermost seta on fourth and fifth endopodal segments of 

 maxilliped vestigial in Arietellus, but not in Paraugaptiloides 

 and Paramisophria; (9) seta a on the sixth endopodal segment 

 of maxilliped reduced only in Paraugaptiloides and Arietellus; 

 (10) the presence of vestigial element on inner distal angle of 

 coxa of leg 4 (shared with Paraugaptilus); (11) left leg 5 

 endopod 2-segmented in Paraugaptiloides and Arietellus, but 

 1-segmented in Paramisophria; (12) right endopod of leg 5 

 present in Paraugaptiloides and Arietellus, but absent in 

 Paramisophria. 



Etymology. The name refers to the close relationship of 

 the new genus to Paraugaptilus. 



Ecological note. The male of P. magnus was first col- 

 lected from 1697 m depth off New Zealand (Bradford, 1974), 

 and has been reported recently from the near-bottom 

 (1060-1070 m depths) in the southwestern Indian Ocean 

 (Heinrich, 1993). It is likely that P. magnus is widely distrib- 

 uted in deep waters of the Indo-Pacific region. Although the 

 species was collected from the near-bottom in the Indian 

 Ocean (Heinrich, 1993), the well-developed antennules sug- 

 gest a relatively loose association with the bottom (Cam- 

 paner, 1984). 



Paraugaptiloides magnus, new combination (Figs 

 11-12) 



Material examined, cf , holotype, New Zealand Oceano- 

 graphic Institute H-199. 



Body length. 4.85 mm (after Bradford, 1974). 



Description. Cephalosome separate from first pedigerous 

 somite. Caudal ramus with setae II- VI well developed. 



Left antennule (Fig. 11A,B) 19-segmented, the fusion 

 pattern and armature elements almost same as in Paraugapti- 

 lus, except for those of segments XXIV to XXVIII: segment 

 XXIV-XXV with large anterior process reaching well beyond 

 antennulary tip (Fig. 11B). Right antennule: segments I to X 

 fringed with long setules along posterior margin; segments X 

 and XI, and XIV and XV only partly fused; segment XXIII 

 and XXIV almost separate; segments XXV and XXVI almost 

 fused with suture visible; fusion pattern and armature ele- 

 ments as follows: I— III— 7 + 3 aesthetascs, IV-2 (element 



