SEVEN SPECIES OF RED SEA ONCAEA 



35 



50 pm 



Fig. 5 Oncaea venusta f. typica, female (Red Sea) Paragnaths, ventral 

 view. 



Syncoxa unarmed, surface ornamented with 2 spinular rows and 2 

 large secretory pores. Allobasis produced distally into slightly 

 curved claw bearing 2 rows of very strong spinules along medial 

 margin; outer margin with strong seta extending almost to tip of 

 allobasal claw, ornamented with few strong spinules distally and a 

 thin hyaline lamella bilaterally, tip of seta with tubular extension; 

 inner margin with slender pinnate seta and strong basally swollen 

 spine with double row of very strong spinules along the medial 

 margin and single row of shorter spinules along outer margin. 



Maxilliped (Fig. 3G) 4-segmented, comprising syncoxa, basis 

 and 2-segmented endopod. Syncoxa ornamented with few spinules 

 on anterior surface, unarmed. Basis robust, inner margin with 2 

 spiniform spinulose elements nearly equal in length; fringe of long 

 setules half the distance between distal seta and articulation with 

 endopod; anterior surface with 2 rows of long spinules along palmar 

 margin, additional longitudinal row of spinules near outer margin as 

 in Fig. 3G. Proximal endopod segment unarmed. Distal endopod 

 segment drawn out into long curved claw, with pinnules along 

 proximal two-thirds of concave margin; accessory armature consist- 

 ing of minute, naked seta on outer proximal margin and unipectinate 

 spine fused basally to inner proximal corner of claw. 



Swimming legs 1^4 biramous (Fig. 4A-D), with 3-segmented 

 rami. Spine and setae formula as for genus. Intercoxal sclerites well 

 developed, ornamented with 3 posterior denticles at distal corners in 

 P1-P3. Coxae and bases of legs 1-4 with surface ornamentation as 

 in Fig. 4A-D. Coxae of P1-P4 with posterior raised secretory pore 

 near outer distal corner (not figured, cf. Fig. 13A-D). Bases with 

 short naked (P1-P3) or plumose (P4) outer seta; with anterior 

 secretory pore near outer proximal corner; inner portion slightly 

 produced medially in P2-P4 (Fig. 4B-D). Inner basal seta on PI 

 spiniform and minutely pinnate. Respective legs without distinct 

 length differences between exopod and endopod (P 1 ) or with endopod 

 slightly longer than exopod (P2-P4). Bases of spines on exopod and 



endopod segments anteriorly surrounded by small spinules. Ante- 

 rior face of all segments ornamented with small scales (not figured), 

 similar to those on caudal ramus (Fig. 2F). 



Exopods. Outer margin of exopod segments with well developed 

 serrated hyaline lamella, interrupted by small gap at about half the 

 distance, longitudinal concavity below serrated lamellar margin 

 (Fig. 9E); inner margin of proximal exopod segments with long 

 setules. Secretory pore present on posterior surface of distal seg- 

 ments. Hyaline lamellae on outer spines well developed; outer and 

 terminal spines of PI with subapical tubular extension (Fig. 9F). 

 Terminal spine shorter than distal exopod segment in all legs. 



Endopods. Outer margin of endopod segments with fringe of long 

 setules. Inner seta of proximal endopod segment slightly swollen at 

 base. Distal endopod segments with several secretory pores on 

 posterior surface; distal margin of P2 and P3 produced into conical 

 projection ornamented with minute spinules anteriorly (Fig. 4B,C). 

 Outer subdistal spine nearly equal in length to (P2-P3) or shorter 

 than (P4) outer distal spine, always shorter than distal spine. Outer 

 distal spine about 3/4 the length of terminal spine in P4. Outer 

 margin of distal segment of PI terminating in a long process 

 obscuring insertion of distalmost inner seta (Fig. 4A). Inner setae of 

 distal endopod segments with spinule comb along proximal inner 

 margin; this comb also present on distal inner seta of middle 

 endopod segment in P3-P4. 



P5 as figured for O. venusta f. venella (cf. Fig. 1 1G), comprising 

 small plumose seta arising from lateral surface of somite, and small 

 free unornamented segment representing exopod. Exopod slightly 

 longer than wide, bearing 2 naked setae nearly equal in length, 

 subapical one spiniform. 



P6 (Fig. 2G) represented by operculum closing off each genital 

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

 8B), only I of which discernible under light microscope (Fig. 2G). 



Egg-sacs paired, oval-shaped; each sac containing appr. 3GM-0 

 eggs (diameter 50-60 urn). 



ADULT MALE (Figs. 6, 7A-C, 8F, 10). 



Body length: 1 1 58 urn [traditional method: 910 urn, range: 880-950 

 um, based on 9 specimens (Bottger-Schnack et cil.. 1989)]. Sexual 

 dimorphism in antennule, antenna, maxilliped, genital segmentation 

 and ornamentation. P1-P3 (endopod). P5-P6, and in caudal ramus. 



Prosome 2.0 times the length of urosome, excluding caudal rami. 

 1.7 times urosome length, including caudal rami. 



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

 10.1 :64.5 : 6.0: 4.4: 5.0: 10.1: proportional lengths (%) of uroso- 

 mites (caudal rami included) 8.6 : 55.0 : 5.1 : 3.7 : 4.3 : 8.6 : 14.7. 

 Length to width ration of genital somite 1.5 : 1. Caudal rami about 

 2.5 times longer than wide, shorter than in female. Caudal setae with 

 proportional lengths as in female, except for seta VI, which is about 

 2/3 the length of seta IV and 2.2 times the length of caudal ramus. 

 Dorsal and ventral surface of caudal ramus covered with minute 

 scales as in female. Surface of genital flaps and ventral surface of 

 anal segment ornamented with several rows of small spinules. 

 Ventral face of anal somite with paired secretory pore near posterior 

 margin (Fig. 6E). 



Antennule (Fig. 6B) 4-segmented; distal segment corresponding 

 to fused segments 4-6 of female; relative lengths (%) of segments 

 measured along posterior non-setiferous margin 8.0 : 27.1 : 43.3 : 

 23.6. Armature formula: l-[3], 2-[8], 3-[4], 4-[ll+2ae+(l+ae)]. 



Antenna (Fig. 6H) with seta on coxobasis naked and shorter than 

 in female. Distal endopod segment with seta III much stouter than in 

 female, seta IV spiniform and curved, both elements shorter than in 

 female (Fig. 8F). 



Maxilliped (Fig. 6C) 3-segmented, comprising syncoxa, basis 



