BARGMANNIA REVISION 



63 



gonophore contains two eggs. This is a highly unusual situation as, 

 according to Carre and Carre (1995) all other physonect siphono- 

 phores have only one egg in each gonophore. However, Totton 

 (1965) states that the gonophores of Pyrostephos vanhoeffeni con- 

 tain from three to five eggs. 



Distribution. Much of Totton's (1954, 1965) Bargmannia 

 material, from early Discovery collections, is so poorly preserved 

 that it is difficult to be certain to which species it belongs. However, 

 as noted earlier, the nectophores from Discovery Sts. 699 and 681, 

 from the South and North Atlantic Ocean respectively, belong to B. 

 elongata; as does that from Discovery St. 107 from south of South 

 Africa. Several other of his nectophores probably belong to B. 

 amoena, but this has not been established with certainty. 



The great majority of the 8500+ nectophores of Bargmannia spp. 

 that have been identified from over 300 recent Discovery samples, 

 mainly from the North east Atlantic Ocean, belong to either B. 

 elongata or B. amoena. However, these identifications were made 

 before it was realised that two similar species were present. A re- 

 examination of some of the material, however, typically showed that 

 the material was too poorly preserved for specific identification. 

 However, it was clear that B. amoena, not B. elongata, was the 

 predominant species of the genus at c. 44°N, 13°W, where an 

 extensive series of collections was made(Pugh, 1984). Collectively, 

 both species have a widespread distribution in the North-east Atlan- 

 tic Ocean; from the equator to 60°N, with possibly/?, elongata being 

 more common at lower latitudes and B. amoena at higher ones. 

 Nectophores have been collected at all depths from the surface to 

 4520 m, but the vast majority were found in samples from between 

 200 and 600 m. 



Most of the 67 specimens of B. amoena collected by the sub- 

 mersibles./SL I and II came from a relatively small area in the region 

 of The Bahamas, from 25°03' to 26°36'N and 77°23' to 78°44'W. 

 Five others were collected near the Dry Tortugas, between Florida 

 and Cuba, at c. 24°30'N, 83°45'W. All were collected over a wide 

 depth range, from 435 to 910 m, with a mean depth of 625 ± 130 m. 

 This mean depth is slightly deeper than the depth range for both B. 

 elongata and B. amoena found in Discovery net collections. How- 

 ever, both figures probably are biased because, in the case of the 

 submersible, most observations and collections were made within 

 the 600-900 m depth range, while at 44°N, 1 3°W for instance, most 

 of the net sampling was concentrated in the top 600 m of the water 

 column. 



Remarks concerning the identification of Bargmannia 

 AMOENA. Complete and well-preserved specimens of B. amoena 

 easily can be distinguished from the other Bargmannia spp. as they 

 have very distinctive bracts. However, if only poorly preserved 

 nectophores are present, then there may be some difficulty in 

 separating this species from B. elongata. They cannot be confused 

 with B. gigas, because of the relatively enormous size of the latter's 

 nectophores; and should not be confused with B. lata. The much 

 narrower nectosac of the latter species, together with the greater 

 depth of the furrow between its deep lateral wings, should easily 

 distinguish it. 



As noted above, the best feature distinguishing B. elongata and/?. 

 amoena is the arrangement of the apico-lateral ridges. InB. elongata 

 these have a pair of side branches, running down toward the mid- 

 line, while in B. amoena such side branches are absent. In addition, 

 in B. elongata, at the point where these side branches arise, the 

 apico-laterals bend sharply outwards, through 90°, while in B. 

 amoena the apico-laterals only curve gently away from the mid-line. 

 Unfortunately, it is this region of the nectophore that most often 

 becomes distorted in poorly preserved specimens and these distin- 



guishing features can be masked. This can result in the distinct, 

 right-angle bend in the apico-lateral ridges of B. elongata coming to 

 resemble the much smoother curve in B. amoena or, conversely, 

 those of the latter species becoming distorted to form distinct bends 

 resembling those of the former. The side branches to the apico- 

 laterals in B. elongata often are difficult to discern, but usually show 

 up after staining. 



Another obvious difference, despite its subjectiveness, is the 

 density of the musculature on the nectosac. Nectophores with almost 

 opaque nectosacs appear to belong to B. elongata, while those with 

 translucent nectosacs belong to B. amoena. In addition, the ratio of 

 the total length of the nectophore to that of the nectosac may be of 

 use. In B. elongata this ratio, in well-preserved specimens, averages 

 1.31, while in B. amoena it averages 1.42. However, with poorly 

 preserved material, particularly when the basal half of nectophore is 

 damaged, both measurements could be underestimated, which would 

 lead to a corresponding increase in the ratio. 



Other features of the nectophore that might be considered include 

 the fact that in B. amoena the outer branch of the apico-lateral ridges 

 peters out higher above the ostium than in B. elongata. Also, the 

 lateral processes to the ostium are much larger in B. elongata. In 

 addition, the angle at which the ostium opens is very characteristic 

 in well-preserved material. In B. elongata the ostium is directed 

 dorso-basally while in B. amoena it opens basally. However, all 

 these features might be difficult to discern in poorly preserved 

 nectophores The structure of the mouth-plate may be important but, 

 as has been shown forfi. amoena, this may vary according to the size 

 of the specimens. More well preserved specimens of B. elongata are 

 needed in order to assess this. Similarly, this applies to the arrange- 

 ment of the meso-lateral ridges and their basal extensions; and to the 

 profile of the ventral margins of the ventro-lateral wings. 



Etymology. Amoena is Latin for 'pleasing, delightful'. 



Bargmannia lata Mapstone 1998 



Bargmannia elongata Totton 1954 (partim) (text-Figure 28, E-F 



only), 1965 (partim) (Figure 45 E-F only). 

 Bargmannia lata Mapstone 1998; 141-146, figs 1-3. 



HOLOTYPE. In the collections of the British Columbia Provincial 

 Museum, BCPM 996-203- 1 ; one nectophore and one bract collected 

 at St. LC10 (48°22.4'N 126°20.2'W; 24-iv-1987; 700-0m) off 

 British Columbia, Canada; 



Paratypes. As designated by Mapstone; 1. 7 nectophores and 7 

 bracts (BCPM 996-204- 1#1), and 2. 6 nectophores and 6 bracts 

 (BCPM 996-205- 1#2) from the same sample as the holotype; 3. 1 1 

 nectophores (BCPM 996-206- 1#3), and 6. 1 bract (BMNH 

 1996.1 239- 1240#6) from St.A4 (48°15'N 126°40'W; 21.iii.87; 500 

 m); 4. 8 nectophores (0-700m; BCPM 996-207- 1#4), and 5. 14 

 nectophores and 2 bracts (BMNH 1996.1234-1238#5) from St. 

 LB17 (47°56.5'N 126°26.1'W; 21.iii.87; 700m). 



Material examined. One specimen collected during Alvin Dive 

 966 off San Diego, California, U.S.A.; 33°04'N 118°16'W; 8-ix- 

 1979; water depth 747m. The depth of collection of the specimen 

 was not recorded. 



Two nectophores collected at Discovery St. 1 769, and figured by 

 Totton (1954, Text-Figure 28, E, F; 1965, Figure 45, E, F) as 

 B. elongata; 33°43.3'S 8°38.5'E; 20-V-1936; 1000-750 m; NHML 

 1957.5.15.110. 



In addition, the specimens that Totton included under the name 

 B. elongata have been re-examined. Although not all are in good 

 condition, the following appear to belong to B. lata:- 



