70 



R. BOTTGER-SCHNACK 



Table 6 Abundance (individuals beneath 0.25m 2 ) of O. scottodicarloi adults in the Gulf of Aden and different regions of the Red Sea during summer 

 1987. 















Red Sea Main Basin 









Gulf of Aden 



Bab al Mandab 



South, shallow 



South, deep 



Central 



North 



Stn. 



631 



633 



717 



708 



703 



682 



663 



Sampling Time 



N 



D 



D 



D 



D 



D 



D 



Total water depth (m) 



1400 



1300 



250 



190 



970 



1890 



1200 



Depth layer (m) 

















0-100 



2800 



2000 



5000 



380 



300 



770 



850 



100-250 



160 



- 



330 



620* 



81 



220 



380 



250-450 



- 



- 







91 



350 



620 



450-1050 



- 



- 







7** 



28 



130 



Corrected data of Table 8 in Bottger-Schnack (1995) 

 D = Day; N = Night; - = no data; Stn. = Station number 

 * = Depth range 100-175m 

 ** = Depth range 450-950m 



Vertical distribution and vertical migration 

 In the Red Sea, O. scottodicarloi had an epi- and mesopelagic 

 distribution mainly between the surface and 600 m depth in the Red 

 Sea; individual finds occurred down to 1250 m. Females exhibited a 

 bimodal vertical distribution pattern, with maximum abundances in 

 the epipelagic zone (0-1 00m) and in the mesopelagic zone, at 200- 

 400(450) m depth (Bottger-Schnack, 1990a, b and unpubl. data from 

 summer 1987). The depth horizon of the two population centres 

 varied seasonally, with the epipelagic mode shifting to shallower 

 depth during winter, due to absence of a strong thermocline, as well 

 as regionally, with the mesopelagic mode shifting to shallower depth 

 in the South as compared to the central-northern area. In general, 

 however, the bimodal pattern was consistent. Diurnal vertical mi- 

 gration of moderate intensity was observed only for the epipelagic 

 part of the female population during autumn, which migrated up- 

 wards at night. During winter, the vertical migration behaviour of 

 the species was not investigated. 



In contrast to females, males of O. scottodicarloi exhibited a 

 unimodal distribution pattern in the epipelagic zone, with highest 

 densities in the upper 50 m (winter, summer) or in the 50-100 m 

 zone (autumn). Within this depth zone, their diurnal vertical migra- 

 tion was stronger than in the females. 



The mesopelagic population centre of O. scottodicarloi did not 

 show a regional downward shift between the central and northern 

 Red Sea in relation to the regional differences in oxygen profiles, as 

 had been observed for other oncaeids exhibiting bimodal distri- 

 bution patterns in the area, such as O. mediterranea and Lubbockia 

 squillimana (Bottger-Schnack, 1990b). During summer, however, 

 the lower part of the population occurred somewhat shallower in the 

 southern Red Sea (200-300 m) than in the central-northern area 

 (250-400/450 m) (own unpubl. data). This might be related to a 

 corresponding regional shift in the depth of the oxygen minimum 

 (Bottger-Schnack, 1995). However, as the sampling variability 

 within each area was not investigated during the summer, the data 

 are inconclusive. 



In the shallow part of the southern Red Sea (SRS) and in the Strait 

 of Bab al Mandab (BaM), both sexes of O. scottodicarloi were found 

 more or less evenly distributed between 40 m and the near-bottom 

 layer at 175 m (SRS) or occurred in maximum concentrations 

 between 20-60 m depth (BaM) during summer (unpubl. data). In 

 this area, the population occurred at the same depth as O. waldemari, 

 but the two species were vertically separated from O. media, which 

 was concentrated much shallower, at 0-20 m (BaM). 



Seasonal variation in abundance (central red sea) 



O. scottodicarloi exhibited no consistent seasonal variation in 



abundance in the central Red Sea, indicating that the species is not 

 markedly influenced by seasonal inflow of southern Red Sea waters 

 (Bottger-Schnack, 1995, see also above under 'Size variation'). 



Oncaea waldemari Bersano & Boxshall, 1994 



Oncaea waldemari Bersano & Boxshall (1994): 29-^41, Figs. 1-6. 



Oncaea media f. minor Malt (1982b): 130-133, Figs, la-i, 2a-j, 

 3a-z\ 4a-o, 5a-h. 



Type locality. 

 52°20W) . 



Southern Brazilian shelf (3 1 o 40'-33 o 45'S, 5 1 °00'- 





Preliminary note. The type description by Bersano & Boxshall 

 (1994) includes some inconsistencies between text and figures, in 

 particular with regard to P5 exopod, that severely hampers a positive 

 identification of the species. Re-examination of the type material of 

 O. waldemari during the present study gave unequivocal evidence 

 that specimens from the Red Sea are conspecific. The species is 

 redescribed based on Red Sea specimens (figures) and the type 

 material. It includes several morphological details which were not 

 mentioned in the original account (e.g. labrum). Also, body dimen- 

 sions of specimens from the Red Sea, calculated by the different 

 methods used throughout this study, are provided. The urosome 

 segmentation of a typical female Copepodid Stage V, which has 

 been incorrectly described for oncaeid copepods in the literature 

 before, is described and briefly discussed. 



Material examined. 



(1) Southern Red Sea, 13° 40.0'N, 42° 37.4'E: Stn. 708; R/V Meteor 

 leg 5/5: collected 05 August 1987 with MSN 0.05 mm net (Haul 

 47/3); depth 20-40 m; total water depth 190 m. 



(a) 2 99 in alcohol (BMNH 1998.2816-2817). 



(b) 2 99, 1 6 in alcohol (ZMH K-39583). 



(c) 2 99, 3 do* dissected on slides; 2 99, 1 6* in alcohol (RBS). 



(2) Southern Red Sea, 13° 40.0'N, 42° 37.4'E: Stn. 708; R/V Meteor 

 leg 5/5: collected 05 August 1987 with MSN 0.05 mm net (Haul 

 47/2); depth 40-60 m; total water depth 190 m. 



(a) 2 88 in alcohol (BMNH 1998.2818-2819). 

 (b)3 99,3 86 (RBS). 



(3) Southern Brazilian shelf, 31° 40'-33° 45'S, 51° 00'-52° 20'W, 

 collected between 1988-1991 with cylindrical-conical closing 

 net (mesh size 0.15 mm); depth 0-25m: holotype 9 (Stn. 319, 

 BMNH 1994.6213), 2 99paratypes (Stn. 309), 2 8 8 paratypes 

 (Stn. 319) (BMNH 1994.6214-6223). 



(4) Eastern Mediterranean Sea, 34° 25.3'N, 26° 14.8'E, Stn. 35; R/V 

 Meteor leg 5/1 : collected 20 January 1987 with MSN 0.055 mm 





