MARKLE: TAXONOMY AND DISTRIBUTION OF ROULEINA 



motionless by the observation port, one head 

 down, the other more or less on its side. Alepo- 

 cephalus agassizii was observed in similar motion- 

 less positions and were seen to move when 

 disturbed, so that the motionless positions are 

 probably not a sign of death. The observation of 

 mucus is, as yet, uncorroborated by others. How- 

 ever, Koehler (1896:518) described the fresh con- 

 dition of the holotype of B. mollis as being flaccid 

 as a holothurian and retrieved from the trawl in a 

 thick mucus. The split skin along the dorsal and 

 ventral midline commonly observed in preserved 

 specimens of Rouleina may be related to fat and 

 mucus concentrations in these regions of the body. 

 The function of these concentrations and the 

 mucus sheets is unknown. 



All of the R. attrita and most of the i?. maderen- 

 sis were from bottom trawls, but two of the smaller 

 R. maderensis, 86.7 and 177 mm SL, were from 

 nonclosing midwater trawls. It is possible that the 

 rather amorphous and almost degenerate photo- 

 phores (based on microsections from a 236-mm SL 

 specimen) of demersal adult R. maderensis repre- 

 sent organs which are functional only in meso- 

 pelagic juveniles. 



DISTRIBUTION 



Both species are known from the southeastern 

 Pacific and North Atlantic, while i?. attrita is also 

 known from the South Atlantic and southwestern 

 Indian Ocean (Figure 4). The two species have 

 been caught in the same net once in the western 

 Atlantic and once in the southeast Pacific. Al- 

 though the geographic distributions are similar, 

 R. attrita andi?. maderensis segregate sharply by 

 depth. Thirty of 33 specimens (91%) of/?, mad- 

 erensis were from bottom trawls fished between 

 595 and 1,200 m. In contrast, 66 of 75 specimens 

 (88% ) ofi?. attrita were from bottom trawls fished 

 between 1,400 and 2,100 m. 



Off the east coast of the United States, the most 

 consistent physical characteristic between 1,200 

 and 1,400 m is the 4°C isotherm (VIMS unpubl. 

 data, Churgin and Halminski 1974a). However, in 

 the Gulf of Mexico (Churgin and Halminski 

 1974b) and eastern North Atlantic (Lenz 1975), 

 the 4°C isotherm is considerably deeper. A charac- 

 teristic feature of the demersal ichthyofauna on 

 the continental slope off Virginia is a sharp in- 

 crease in mean weight of individual fish around 

 1,500 m (Markle 1976; C. A. Wenner and J. A. 

 Musick pers. commun.). Consistent with this 



phenomenon is the observation of generally larger 

 body size in the deeper dwelling R. attrita com- 

 pared with its shoaler dwelling congener, R. 

 maderensis. Although this suggests a possible bio- 

 logical factor in their distribution, a lack of ap- 

 propriate ecological data for most of the available 

 collections precludes such a statement. Without 

 comprehensive ecological information for all col- 

 lections, the mechanism of bathymetric segrega- 

 tion in the two Atlantic species of Rouleina re- 

 mains unknown. 



ACKNOWLEDGMENTS 



I am grateful to the following individuals and 

 institutions for loan of material: D. M. Cohen, 

 National Marine Fisheries Service, Systematics 

 Laboratory; R. H. Gibbs, Jr., S. H. Weitzman, and 

 S. Karnella, USNM; M. L. Bauchot, MNHN; A. 

 Wheeler, BMNH; G. Krefft, ISH; R. K. Johnson, 

 FMNH; C. R. Robins, UMML; K. Liem and R. 

 Schoknecht, MCZ; N. R. Merrett, lOS; T. Abe, 

 UMT; J. Nielsen and E. Bertelsen, ZMUC; G. E. 

 Maul, MMF; J. A. Musick, VIMS; and C. Karrer, 

 ZMB. Travel expenses were partly defrayed by the 

 1976 Raney Award from the American Society of 

 Ichthyologists and Herpetologists and a Grant- 

 in-Aid of Research from Sigma Xi. This work was 

 supported in part by NSF grant No. GA-37561 and 

 OCE 73-06539, J. A. Musick principal inves- 

 tigator. 



LITERATURE CITED 



ANONYMOUS. 



1974. Deep water trawl fish tested for food market. Fish. 

 News Int. 13(l):47-49. 



Bauchot, M.-L., T. Iwamoto, p. Geistdoerfer, and M. 

 Rannou. 



1971. Etude critique des resultats des expeditions scien- 

 tifiques du "Travailleur" et du "Talisman". Nouvel exa- 

 men des Macrouridae (Teleosteens Gadiformes). Bull. 

 Mus. Natl. Hist. Nat., Paris, 3e Ser., Zool. 14:653-666. 

 BEEBE, W. 



1933. Deep-sea isospondylous fishes, two new genera and 

 four new species. Zoologica (N.Y.) 13:159-167. 

 BEST, A. C. G., AND Q. Bone. 



1976. On the integument and photophores of the alepo- 

 cephalid fishes Xenodermichthys and Photostylus. J. 

 Mar. Biol. Assoc. U.K. 56:227-236. 



Churgin, J., and S. J. Halminski. 



1974a. Temperature, salinity, oxygen, and phosphate in 

 waters off United States. Vol. 1. Western North Atlan- 

 tic. U.S. Dep. Commer., Natl. Ocean. Atmos. Admin., 

 Environ. Data Serv., Key Oceanogr. Rec. Doc. 2, 166 p. 



1974b. Temperature, salinity, oxygen, and phosphate in 

 waters oflF United States. Vol. 2. Gulf of Mexico. U.S. 



85 



