56 



R. BOTTGER-SCHNACK 



100jjm 



Maxilliped as figured by Heron & Bradford-Grieve (their Fig. 

 17f). 



Swimming legs 1^4 with armature and ornamentation as in 

 female; sexual dimorphism expressed in (1) terminal process on PI 

 endopod (obscuring insertion of distalmost seta), being relatively 

 longer than in female (similar to O. scottodicarloi, Fig. 231), (2) 

 terminal conical projections on distal endopod segment of P3 (not on 

 P2) longer than in female, reaching 2/3-3/4 the length of outer distal 

 spine and (3) reduced spine lengths in endopod spines of P2-P4 

 (Table 4). 



Table 4 Sexual dimorphism in spine length (pm) on distal endopod seg- 

 ment of P2-P4 in O. media from the Red Sea. (Data represent single 

 measurements). 



Spine length 

 Female Male 



Male : female (%) 



P2 









Outer subdistal spine 



20.0 



10.0 



50 



Outer distal spine 



18.1 



7.5 



41 



Distal spine 



26.3 



11.3 



43 



P3 





left/right 





Outer subdistal spine 



18.8 



10.6/11.3 



57/60 



Outer distal spine 



19.4 



10.6/13.8 



55/71 



Distal spine 



32.5 



25.6/25.6 



79 



P4 









Outer subdistal spine 



24.3 



16.3 



67 



Outer distal spine 



26.3 



20.6 



78 



Distal spine 



43.8 



31.3 



72 



Fig. 16 Oncaea media, male (Red Sea) (A) Habitus, dorsal; (B) P5. 

 dorsal; (C) P6, aberrant posterolateral corner arrowed. (D) antenna, 

 anterior: (E) mandible, blade C. 



P5 (Fig. 16B) exopod fused to somite, length of segment shorter 

 than in female; proportional lengths of exopodal setae as in female. 



P6 represented by posterolateral flap closing off genital aperture 

 on either side; covered by pattern of denticles as in Fig. 16C; 

 posterolateral corners with single pointed tip, occasionally with 

 bifid tip (arrowed in Fig. 16C). 



Taxonomy 



Giesbrecht ( 1 89 1 : 477) presented a short latin diagnosis of O. media 

 and subsequently described the species in more detail from the 

 Mediterranean, Naples area (Giesbrecht, 1892). Recently, Heron & 

 Bradford-Grieve (1995) redescribed O. media from the Gulf of 

 Naples and in the same account described a closely related species, 

 O. scottodicarloi, which co-occurred with O. media in the Gulf. The 

 authors pointed out an important discrepancy in Giesbrecht's ( 1 892) 

 description of O. media: all of his figures of the species matched O. 

 media as re-examined by Heron & Bradford-Grieve, except for his 

 Plate 47, Fig. 11, dorsal view of female urosome, which resembled 

 that of the newly described O. scottodicarloi. [In this context it 

 should be noted that Heron & Bradford-Grieve (1995) recorded 

 several undescribed species similar to O. media and O. scottodicarloi 

 in their Gulf of Naples samples, indicating that a complex of species 

 close to O. media exists, which is as yet undescribed. One of the 

 species belonging to this complex is undoubtedly O. waldemari, 

 whose taxonomic position will be re-evaluated below.] 



Specimens of O. media from the Red Sea met all important 

 characters described by Heron & Bradford-Grieve, including pat- 

 terns of integumental pores on the prosome of both sexes. Slight 

 differences in Red Sea specimens included ( 1 ) the armature on 6th 

 segment of antennule, the minute sensory element not noted by 

 Heron & Bradford-Grieve, (2) additional surface ornamentation on 

 coxobasis of female antenna and (3) spine lengths on P2-P4 enp-3 in 

 the male. The first two characters are difficult to discern and may 

 have been overlooked in the previous description. The reduction of 

 spine lengths on P2-P4 enp-3 in male O. media was less pronounced 



