64 



R. BOTTGER-SCHNACK 



200 ^m 



Fig. 21 Oncaea clevei (Red Sea) (A) Female and male, mating position, 

 lateral, appendages of female and swimming legs of male omitted. 

 Oncaea clevei, male (Red Sea) (Bl, B2) P2, distal part of endopod, 

 showing variation in spine length. (C) P3, distal part of endopod. 



P6 (Fig. 20E) represented by posterolateral flap closing off 

 genital aperture on either side; covered by pattern of denticles as 

 shown in Fig. 20E. 



Spermatophore oval (Fig. 20E, F), of variable size according to 

 state of maturity. 



Taxonomy 



Friichtl( 1923) gave a first short diagnosis of O. clevei based on a 

 single female collected near the Aru Archipelago, off Wokam, and 

 subsequently described it in more detail (Friichtl,1924). The second 

 account included additional specimens of O. conifera sensu Cleve 

 ( 1 90 1 ) from the Indo-Malayian Archipelago, which had been sent to 

 Friichtlby G.O. Sars (Friichtl, 1924, footnote to p.89 (111)), and 

 which he had synonymized with O. clevei after re-examination. 

 Friichtls figures of the female urosome (1923: Tafel 26, Fig. 19; 

 1924: Fig. 24) show an extremely lateral position of the genital 

 apertures and a sickle-shaped sclerotization between, but slightly 

 posterior to, the genital apertures. This combination of characters 

 enables unequivocal identification of the Red Sea specimens with 

 Friichtls O. clevei. The closely related O. paraclevei sp. nov., which 

 co-occurs with O. clevei in the Red Sea, differs in the location of 

 genital apertures and in the form of sclerotization (see below under 

 'Remarks' of O. paraclevei). Red Sea specimens of O. clevei differ 

 slightly from the original account in the length of the outer distal 

 spine on P4 enp-3, which is about half the length of the distal spine, 

 whereas it is shorter in O. clevei sensu Friichtl. The length of the 

 outer subdistal spine on enp-3 in P2 (shorter in Red Sea specimens) 

 and P3 (longer in Red Sea specimens) is also slightly different 

 between the two descriptions. 



Friichtl (1924) erroneously recorded the armature of PI enp-3 

 with 4 inner setae (his Fig. 66 and p. 91), but in the same account 

 described the 'aberrant* condition of the type specimen from Wokam, 

 which exhibited 5 inner setae (his Fig. 15). The 5th inner seta on PI 

 enp-3 has repeatedly been overlooked in previous descriptions of 

 this and other species of Oncaea s.str. (see above e.g. O. venusta), 

 because the base of the seta is concealed beneath the long anterior 

 spinous outgrowth of the segment (cf. Fig. 19A). 



Males of O. clevei were not recorded by Friichtlor in any reliable 

 subsequent account. Their description here is based on specimens 

 taken from male-female pairs in mating position (Fig. 21 A), which 

 represents the highest probability of encountering a conspecific 

 male of a given species (but see Heron & Bradford-Grieve, 1995 for 

 exceptions). O. clevei males are very similar in size and habitus to 

 those of O. venusta f. venella. However, differences in the ornamen- 

 tation of the labrum (see below) as well as in proportional lengths of 

 caudal setae separate the two species. 



O. clevei is closely related to O. paraclevei sp. nov., from which 

 it can be distinguished mainly by the location of genital apertures, 

 the form of the genital double-somite and by further morphological 

 characters summarized under Remarks. O. paraclevei. Together, the 

 two species form a well-defined group within Oncaea s.str., which is 

 characterized by the presence of a dorso-posterior projection ( 'hump' ) 

 on the P2-bearing somite in the female and by the absence of long 

 setules on the latero-distal margin of the lobes in the labrum. As the 

 hump is a sexually dimorphic character, which is not found in males, 

 males of the two subgroups can only be distinguished by differences 

 in the ornamentation of the labrum, otherwise they are very similar. 



Other records of o. clevei 



Malt (1983a) summarized the published records of O. clevei and 

 found it restricted to surface waters in low latitudes of the western 

 Pacific and Indian Ocean. In view of the existence of a hitherto 

 undescribed species, which is extremely close to O. clevei, it may be 

 assumed that both O. clevei and O. paraclevei may have been 



