SEVEN SPECIES OF RED SEA ONCAEA 



71 



net (Haul 24/5); depth 0-50 m; total water depth 3400 m: 1 ?in 

 alcohol (RBS). 



(5) Northern Arabian Sea, near Oman, 20° 44.3'N, 59° 40.5'E: Stn. 

 347; R/V Meteor leg 5/3a: collected 05 April 1987 with MSN 

 0.05 mm net (Haul 8/1 ); depth 0-50 m; total water depth ca 2500 

 m: 5 99, 2 o*6* for length measurements (RBS). 



(6) Plymouth Sound, BMNH 1981.229, labelled Oncaea media 

 (sensu Malt, 1982): 3 99, 2 66 in alcohol. 



(7) Adriatic Sea, 42° 38.5'N, 18° 02.0'E: Stn. -Lokrum 100'; col- 

 lected 26 September 1 996 with 0.053mm Nansen type net; depth 

 0-25 m, vertical haul (leg. F. Krsinic): 2 99(1 ovigerous), 1CV 

 9, 1 6* in alcohol (RBS). 



(8) Eastern Indian Ocean, NW Cape Australia, 21° 49.86'S, 114° 

 30.3, E: Stn. B; NWC 005/2; RV 'Lady Basten' leg 1630; col- 

 lected 26 October 1997 with 0.5 m WP-2 net with 0.073 mm 

 mesh, vertical haul; depth 0-20 m (leg. D. McKinnon): 2 99 in 

 alcohol (RBS). 



(9) Western Subtropical Pacific, off Sagami Bay (Japan), 34° 15.0'N. 

 139° 45.0^: Stn. \\R/VTansei-Maru leg KT-00-5; collected 09 

 May 2000 with Norpac net with 0.1 mm mesh; depth 0-200 m, 

 vertical haul (leg. S. Nishida; H. Itoh): > 30 99 in alcohol for 

 molecular analysis (RBS) 



Redescription. 



(CV9). 



Note illustrations are based on 1 (c) and (7) 



Adult female (Figs. 24-26). 



Body length: 637 um [Traditional method: 420-500 um, based on 



21 specimens]. 



Exoskeleton well chitinized. Prosome 2.7 times length of urosome, 

 excluding caudal rami, 2.3 times urosome length including caudal 

 rami. P2-bearing somite without conspicuous dorso-posterior pro- 

 jection in lateral aspect (Fig. 24B). Integumental pores on prosome 

 as in Fig. 24A, B. 



Proportional lengths (%) of urosomites 10.3 : 56.6 : 10.7 : 8.7 : 

 12.6. Proportional lengths (%) of urosomites and caudal rami 8.8 : 

 48.1 :9.1 :7.4: 11.6: 15.1. 



Genital double-somite (GDS) of Red Sea specimens 1.7 times as 

 long as maximum width (measured in dorsal aspect) and 1 .7 times as 

 long as postgenital somites combined (Fig. 24C); GDS length to 

 width ratio of three female paratypes from Brazilian waters ranging 

 between 1.6-1.7 : 1, larger than reported by Bersano & Boxshall 

 (1.4:1). Armature of genital apertures represented by 1 spine and 2 

 small spinous processes, as figured by SEM-micrograph by Bersano 

 & Boxshall (their Fig. 5D), the second minute one hardly discernible 

 with light microscope in Red Sea specimens (Fig. 24H). 



Anal somite shorter than caudal rami (Fig. 24C), 3/4 the length of 

 caudal rami in Red Sea specimens; variable in paratype specimens 

 due to differences in length of caudal rami (see below). 



Caudal ramus (Fig. 24F) about 2.3 times as long as wide in Red 

 Sea specimens, longer in paratypes, varying between 2.4-2.8 : 1. 

 Seta VI longer than dorsal seta VII and less than twice the length of 

 caudal ramus; seta VII distinctly longer than seta III. 



Antennule (Fig. 24E) with armature formula as for genus, some 

 elements missing in original account of Bersano & Boxshall (their 

 Fig. 2A); pore pattern as figured (Fig. 24E). 



Antenna 3-segmented (Fig. 25A). Coxobasis with row of long, 

 fine spinules or setules near outer margin and with few additional 

 denticles on proximal part of outer (exopodal) margin, not figured in 

 the original account of Bersano & Boxshall. 



Labrum (Fig. 25B, C) as for O. venusta, except for additional 

 surface ornamentation (paired row of denticles) on anterior face, and 

 integumental pockets either side of median swelling more pro- 

 nounced (Fig. 25B). 



Paragnaths (not figured) as in O. venusta. 



Mandible (Fig. 25D) with surface of coxa unornamented; arma- 

 ture elements as for O. venusta, but dorsal blade with 2 additional 

 dentiform processes along dorsal margin (not only one as figured by 

 Bersano & Boxshall). 



Maxillule (Fig. 25E) as for O. venusta, with the 3 innermost 

 elements on outer lobe similar in length, not innermost one shortest, 

 as erroneously figured by Bersano & Boxshall (their Fig. 3C). 



Maxilla (Fig. 25F) and maxilliped (Fig. 25G) similar to O. 

 venusta. Proximal basal seta of maxilliped slightly longer than distal 

 one (Fig. 25G), not shorter, as erroneously figured by Bersano & 

 Boxshall (their Fig. 3E). 



Swimming legs 1—4 with armature as for genus, surface ornamen- 

 tation as shown in Fig. 26A-D. Exopods and endopods with 

 ornamentation and spine lengths similar to O. venusta, except for 

 terminal spine on P4 endopod relatively longer and hyaline lamella 

 more narrow (Fig. 26D). 



P5 with small exopodal segment clearly delimited from somite 

 (Fig. 24G), not fused as stated by Bersano & Boxshall (p. 35). 

 Exopod slightly longer than wide, ornamented with minute subapi- 

 cal pore and bearing 2 naked setae nearly equal in length, inner one 

 spiniform. Small naked seta arising from lateral surface of somite. 



P6 (Fig. 24H) represented by operculum closing off each genital 

 aperture; armed with a spine and 2 small spinous processes, smaller 

 one hardly discernible in Red Sea specimens. 



Egg-sacs paired, oval-shaped; each sac containing appr. 10-12 

 eggs (diameter ca 50 um). 



Adult male (Fig. 27). 



Body length: 454 um [Traditional method: 340-360 um, based on 6 

 specimens]. Sexual dimorphism in antennule, antenna, maxilliped, 

 PI and P3 (endopod), P5-P6. caudal ramus and in genital segmen- 

 tation. 



Proportional lengths (%) of urosomites (excluding caudal rami) 

 9.3 : 66.8 : 3.3 : 4.7 : 4.2 : 11.5; proportional lengths (%) of uro- 

 somites (caudal rami included) 8.3 : 59.6 : 3.3 : 4.2 : 3.8 : 10.0 : 10.8. 

 Caudal rami about 1.4 times longer than wide, shorter than in 

 female. Caudal setae with proportional lengths as in female, except 

 for seta VI shorter than in female, about same length as seta VII and 

 2.0 times length of caudal ramus. The extreme shortness of seta VI 

 recorded by Bersano and Boxshall (about half the length of seta VII, 

 according to their Fig. 1 D) could not be confirmed upon re-exam- 

 ination of male paratypes. Surface of genital flaps ornamented with 

 several rows of small spinules and area of minute pits as in Fig. 27E. 



Antennule (Fig. 27B) with armature as for genus, pore pattern as 

 figured [distalmost element on segment 2 erroneously figured as 

 belonging to segment 3 in original account. Fig. 2B of Bersano & 

 Boxshall]. 



Antenna as in female, except for third spiniform element on 

 lateral armature being somewhat stouter than in female and fourth 

 element curved and ornamented with vestigial dentiform processes 

 along distal margin (arrowed in Fig. 27H). Seta on coxobasis long 

 and plumose as in female. 



Maxilliped (Fig. 27C) similar to O. venusta. 



Swimming legs 1^1 with armature and ornamentation as in 

 female; sexual dimorphism expressed in terminal process on P 1 enp- 

 3, being relatively longer than in female (Fig. 27J), and in longer 

 terminal conical projection on P3 enp-3, reaching 2/3 the length of 

 outer distal spine (Fig. 27K). 



P5 (Fig. 27G) exopod not delimited from somite, general shape 

 and armature as in female, except for setae slightly shorter than in 

 female; small naked seta arising from lateral surface of somite as in 

 female. 



