SEVEN SPECIES OF RED SEA ONCAEA 



59 



(c) 1 8 (from mating pair) dissected on 9 slides, 1 9(ovigerous, 

 from mating pair) in alcohol, 1 9, 1 8 (mating position) in 

 alcohol (RBS). 



(4) Northern Arabian Sea, 19° N, 65° E: Stn. 247; R/V Meteor leg 

 32/3: collected 14 May 1995 with MSN 0.05 mm net (coll. L. 

 Postel); depth 0-50m; total water depth ca 3000 m: 1 9dissected 

 on 11 slides, 1 9 in alcohol (RBS). 



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

 347; RN 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: 6 99 in alcohol (RBS). 



(6) Pacific Ocean, Great Barrier Reef; further sampling data not 

 specified; leg G.P. Farran, 1928-1929, cf. Farran (1936); 10 

 specimens in alcohol, labelled Oncaeu clevei (BMNH 

 1949.12.31.516): this vial contains 5 99ofO. clevei, 1 prosome 

 with dorsal hump and 4 damaged prosomes; 2 urosomes ( 1 of O. 

 clevei, 1 possibly of O. paraclevei sp. nov.), and 2 bits of 

 calanoid copepods). 



(7) Pacific Ocean, Great Barrier Reef; further sampling data not 

 specified; leg G.P. Farran, 1928-1929. cf. Farran (1936); more 

 than 10 specimens in alcohol, labelled Oncaeu clevei (BMNH 

 1948.4.28.140): this vial contains 22 99 of O. clevei. 1 8 

 Corycaeidae indet., 1 calanoid copepod. 



Description. Note illustrations are based on (2a-2c) and (4). 



Adult female (Figs. 17-19, 21 A). 



Body length: 810 urn [traditional method: 640 um, range: 620-680 



um, based on 4 specimens]. 



Exoskeleton well chitinized. Prosome 2.4 times length of urosome. 

 excluding caudal rami, 2.1 times urosome length including caudal 

 rami. P2-bearing somite with conspicuous dorso-posterior projec- 

 tion in lateral aspect ( Fig. 1 7B ), not varying in size between specimens 

 examined. Integumental pores on prosome as indicated in Fig. 17A, 

 B. Pleural areas of P4-bearing somite with rounded posterolateral 

 corners. 



Proportional lengths (%) of urosomites 11.4 : 55.3 : 10.1 : 10.1 : 

 13.1. Proportional lengths (%) of urosomites and caudal rami 9.6 : 

 46.5:8.5:8.5 : 11.0: 16.0. 



Genital double-somite almost rectangular in dorsal aspect. 1.4 

 times as long as maximum width (measured in dorsal aspect) and 1 .6 

 times as long as postgenital somites combined (Fig. 17C); largest 

 width measured near anterior margin, lateral margins of genital 

 double-somite rounded at anterior quarter, posterior part tapering 

 slightly. Paired genital apertures located very close to dorsolateral 

 margin at about 2/5 the distance from anterior margin of genital 

 double-somite; armature represented by 1 spine and 2 minute spinous 

 processes (Fig. 17H). Sickle-shaped sclerotization between, but 

 slightly posterior to genital apertures, pore pattern on dorsal surface 

 as indicated in Fig. 17C. 



Anal somite 1.4 times wider than long; slightly shorter than 

 caudal rami (Fig. 17C). Surface ornamentation mainly as in O. 

 venusta. 



Caudal ramus (Fig. 17F) about 2.3 times as long as wide. Seta VI 

 more than 4/5 length of seta IV and 2.5 times longer than caudal 

 ramus; seta VII about half length of seta VI and longer than seta III 

 (Fig. 17C, F). Inner margin of somite with few long setules. 



Antennule (Fig. 17E) with relative lengths (%) of segments 

 measured along posterior non-setiferous margin 6.7 : 26. 1 : 38.3 : 

 11.1: 4.4 : 13.3. Armature as for genus. 



Antenna (Fig. 18A) similar to O. venusta, except for coxobasis 

 with fewer surface ornamentation and seta III on second endopod 

 segment bipinnate. 



Labrum (Fig. 1 8B,C) as in O. venusta, except for long fine setules 

 missing latero-distally on outer margins of lobes. Anterior surface 

 (Fig. 18B) with row of stout denticles on proximal part of each lobe, 

 which are not found in O. venusta. 



Mandible (Fig. 18D) as in O. venusta, except for blade C 

 ornamented with 1 additional dentiform process halfway on dorsal 

 margin. Maxillule (Fig. 18E), maxilla (Fig. 18F), and maxilliped 

 (Fig. 18G) mainly as in O. venusta. 



Swimming legs (Fig. 19A-D) with armature as for genus and 

 surface ornamentation similar to O. venusta. except for less surface 

 ornamention on coxae and bases, most obvious in P4 coxa, lacking 

 patch of long setules on posterior surface. Endopodal and exopodal 

 spine lengths mainly as in O. venusta, except for terminal spines on 

 endopods of PI, P2 and P4 relatively longer, particularly in P4, 

 reaching more than half the length of distal endopod segment. P2 

 with outer subdistal spine reaching insertion of outer distal spine; P4 

 with outer distal spine shorter than in O. venusta, about 1/2 length of 

 distal spine. Inner basal seta on PI naked; outer basal seta on P3 

 plumose. 



P5 (Fig. 17G) comprising small naked seta arising from lateral 

 surface of somite, and free unornamented segment representing 

 exopod. Exopod twice as long as wide, bearing 2 spiniform, naked 

 setae equal in length, which are straight. 



P6 (Fig. 17H) represented by operculum closing off each genital 

 aperture; armed with a spine and 2 small spinous processes. 



Egg-sacs paired, oval-shaped; each sac containing appr. 15-20 

 eggs (diameter 40-^18 urn) (Bottger-Schnack et ai. 1989). 



Adult male (Fig. 20, 21 A-C). 



Body length: 630 um [traditional method: 540 um, range: 490-570 

 urn, based on 4 specimens]. Sexual dimorphism in antennule, 

 antenna, maxilliped, P2-P3 (endopod) and P5-P6, caudal ramus and 

 in genital segmentation. 



Prosome 2.5 times the length of urosome, excluding caudal rami, 

 2.2 times urosome length, including caudal rami. 



Proportional lengths ( c 7c) of urosomites (excluding caudal rami) 

 12.5 : 66.9 : 4.3 : 4.3 : 4.3 : 7.6; proportional lengths (%) of uro- 

 somites (caudal rami included) 1 1 .0 : 58.9 : 3.8 : 3.8 : 3.8 : 6.7 : 1 2.0. 

 Caudal rami about 1.8 times longer than wide, shorter than in 

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

 for seta VI. which is about 3/5 the length of seta IV and 2.2 times 

 length of caudal ramus; seta VII longer than in female, reaching 

 about 2/3 length of seta VI (Fig. 20A). 



Antennule (Fig. 20B) relative lengths (%) of segments measured 

 along posterior non-setiferous margin 10.0 : 24.1 : 38.2 : 27.6. 

 Armature formula as for genus. 



Antenna (Fig. 20H) as in female, except for seta on coxobasis 

 naked and shorter than in female; lateral armature on distal endopod 

 segment differing from female, with element III being much stouter 

 and element IV spiniform and distinctly curved; both elements 

 shorter than in female. 



Maxilliped (Fig. 20C) similar to O. venusta. 



Swimming legs 1^4- with armature and ornamentation as in 

 female; terminal process on PI endopod as in female; P4 with outer 

 distal spine half length of distal spine as in female; sexual dimor- 

 phism expressed in size of terminal conical projections on distal 

 endopod segment of P2-P3, being relatively longer than in female, 

 reaching 2/3 length (P2) or almost same length (P3) of outer distal 

 spine (Fig. 21B1, B2, C). Variation in spine length as shown in Fig. 

 21B1,B2. 



P5 (Fig. 20G) exopod not delimited from somite, general shape 

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

 female. 



