SEVEN SPECIES OF RED SEA ONCAEA 



29 



somite in males; sometimes additional sexual dimorphism in shape 

 and length of exopodal setae. Genital apertures of female large; 

 located near midregion of dorsal surface of genital double-somite 

 but usually in proximal half; each operculum with small spine and 2 

 minute spinules or spinous processes. 



Male P6 membranous flaps produced posterolateral^ into spinous 

 process; without armature. 



Caudal ramus about 3-4 times as long as wide or shorter, without 

 conspicuous dorsal expansion surrounding base of seta VII. Seta I 

 absent; setae II and III unipinnate; setae IV and V not resilient, 

 relatively rigid and bipinnate; seta VII plumose and distinctly shorter 

 than V; seta VI spiniform and sparsely pinnate. None of setae 

 displaced. Sexual dimorphism expressed in length to width ratio of 

 CR, being smaller in male, and in proportional lengths of caudal setae. 



TYPE SPECIES. Oncaea venusta Philippi, 1843 (by monotypy) 



Other species 



O. mediterranea (Claus, 1863) 



O. media Giesbrecht, 1891 



O. curta Sars, 1916 [not O. curta sensu Boxshall, 1977b] 



*0. clevei Frifchtl, 1923 



[ O. praeclara Humes, 1988] syn. of O. venusta 



O. waldemari Bersano & Boxshall, 1994 



O. scottodicarloi Heron & Bradford-Grieve, 1995 



*0. paraclevei sp. nov. 



Species inquirendae 



Oncaea sp. 1 Ferrari, 1975 



Oncaea sp. 2 Ferrari, 1975 



O. philippinensis (Kazatchenko & Avdeev, 1977) 

 [Species marked with an asterisk (*) belong to the cle m'-subgroup. 

 remaining species belong to renusta-subgroup.] 



Remarks 



Within the Oncaeidae Oncaea s.str. belongs to a lineage comprising 

 the conifera/similis-gwup (Triconia Bottger-Schnack, 1999), the 

 notopus-group and the brocha-group (including O. brocha Heron 

 and O. olsoni Heron). These four groups correspond with species 

 groups 2, 3+4, 6 and 7 recognized by Bottger-Schnack & Huys 

 (1998) and together are considered to form a monophyletic lineage 

 on account of the structure of the labrum (median concavity with 4 

 posterior dentiform processes) and the male maxilliped (palmar 

 margin with multiple overlapping rows of blunt spinules). Oncaea 

 s.str. is considered here as the sistergroup of Triconia on the basis of 

 the presence of integumental pockets on the anterior surface of the 

 labrum and the formation of the dorsoposterior projection on the 

 second pedigerous somite. The fact that the latter character is not 

 expressed in all members of both genera is interpreted as the result 

 of secondary loss which happended convergently in each genus. 

 Oncaea s.str. differs from Triconia in the sexual dimorphism of the 

 antenna (seta II and IV modified in the male), the presence of paired 

 slit-like pores on the anterior surface of the labrum and the absence 

 of a conical process on the distal endopod segment of P4. A more 

 detailed discussion of the phylogenetic relationships of Oncaea 

 s.str. within the Oncaeidae is beyond the scope of this paper and will 

 be published separately (Huys & Bottger-Schnack, in prep.). 



The revised genus includes two subgroups of species, the venusta- 

 subgroup and the c/evei-subgroup. Females of the cleve /-subgroup 

 are characterized by a dorso-posterior projection on the P2-bearing 

 somite, which is lacking in the venusta-subgroup. The dorsal projec- 

 tion on the prosome ('hump') is a sexually dimorphic character, 

 which is absent in males. Thus males of both subgroups are very 

 hard to distinguish. A further morphological character separating 

 the 2 subgroups is found in the ornamentation of the labrum, the row 



of long setules on the latero-distal margin of the lobes being absent 

 in the c/ev<?/-subgroup. 



Oncaea curta Sars, 1916 (p. 228, Plate IV, as Onccea carta) was 

 originally described from the western Mediterranean, near the 

 Moroccoan coast. The species has also been widely recorded at low 

 latitudes in the Atlantic and Pacific [as compiled by Malt (1983a) 

 and Razouls (1996)]. Recently, Heron & Bradford-Grieve (1995, 

 p.41) recorded the species from the Gulf of Naples, but at the same 

 time noted in their samples several as yet undescribed species close 

 to O. media, O. scottodicarloi and O. curta indicating that a complex 

 of species close to O. curta exists within Oncaea s.str. Thus, a 

 number of different species might have been recorded in the litera- 

 ture under the wrong name curta (e.g. Boxshall 1977b, see remarks 

 below) and the geographical records of O. curta appear to be doubt- 

 ful. Due to the identification problems, the species had erroneously 

 been placed into the £>oviwfl/?/-group in the preliminary cladogram 

 of Bottger-Schnack & Huys (1998). The species could not be re- 

 examined during the present study, since no material was available. 

 Therefore. Sars' description was taken as a basis to compare the 

 morphology of O. curta with the closely related O. media, O. 

 scottodicarloi and O. waldemari (see under O. scottodicarloi. Re- 

 marks). A thorough revision of O. curta is needed to clarify the 

 taxonomic confusion surrounding this species. 



Oncaea curta sensu Boxshall (1977b: p. 141-143, Table 1-2. Fig. 

 21a-k) does not belong to Oncaea s. str. Malt (1983a) has already 

 pointed out the similarity of the species with O. illgi Heron, which 

 belongs to the bowmani-gmup as defined in the phylogenetic study 

 of Bottger-Schnack & Huys ( 1998; their species group 5). Common 

 characteristics of this group are very elongate conical processes on 

 the distal endopod margins in P2-P3 and a very robust maxillipedal 

 basis, armed with 2 relatively short setae. Boxshall (1977b) 

 synonymized O. curta with O. oralis Shmeleva, O. longiseta 

 Shmeleva and O. latimana Gordeyeva. as well as with Oncaea sp. 1 

 and 2 of Ferrari (1975), but his opinion was not followed by Malt 

 ( 1983a) nor in the present account. 



Oncaea sp. 1 and sp. 2 described by Ferrari (1975; Oncaea sp. 1: 

 p. 228, Figs. 6E, F, 7A-D; Oncaea sp.2: p.228. Figs. 6G, H, 7E-H) 

 are placed in Oncaea s.str. on the basis of the swimming leg 

 armature, the lack of a conical process on the distal margin of P4 

 endopod, and the size and position of the maxillipedal setae. Malt 

 (1983a) tentatively assigned Oncaea sp. 1 to 0. media Giesbrecht 

 forma minor and Oncaea sp. 2 to both O. curta Sars and O. venusta 

 Giesbrecht f. venella, reflecting the author's undecisiveness on this 

 matter. Since the original description of both species lacks sufficient 

 detail necessary for unequivocal identification, they are regarded 

 here as species inquirendae in Oncaea s.str. 



Myspictosum philippinensis Kazatchenko & Avdeev, 1977 (p. 

 44-47, Fig. 9a-i, lOa-g) has been synonymized with Oncaea s.l. by 

 Malt (1982a; erroneously spelled Myctospictosum by Malt) and her 

 opinion was followed by Huys & Bottger-Schnack (1996/97). The 

 single male of O. philippinensis was found on the gills of the deep- 

 sea fish Myctophum spinosum collected in the Philippine Trench at 

 7255 m, which is the deepest record of an oncaeid species so far. The 

 unusually deep record has been regarded as accidental rather than 

 real (Huys & Bottger-Schnack, 1996/97). O. philippinensis might 

 well belong to Oncaea s.str., based on the modified seta IV on the 

 antenna, which is hook-like as in most other species of the genus. 

 However, the leg armature in Kazatchenko & Avdeev's description 

 is incomplete in P2 (endopod missing) and very unusual in PI, the 

 endopod showing 4 inner setae and 3 outer and distal spines, with a 

 conical process at the distal margin. This combination of armature 

 elements is not found in any oncaeid species known thus far and the 

 species is regarded here as species inquirenda in Oncaea s.str. 



