355'. Nomeus albula: Smith, SFSA No. 855*; 1949: 849; Smith & Smith,
1966: 132'; Parin& Fedoryako, 1981'.
D IX-XIIII,24-28; A I-II,24-29; P 19-24; GR about 8+(15-19); vertebrae 41. Depth 2.6-4.8; head 2.6-4.0. Small conical teeth similar in both
jaws. V greatly expanded in juveniles. Fin spines weak.
Juveniles with striking dark blue mottlings over a whitish
or silvery base; V black. Juveniles associate with the pelagic
siphonophore Physalia and have been observed to feed on
the stinging tentacles, but they also eat chaetognaths and
other pelagic invertebrates (crustaceans, molluscs and
polychaets). Jenkins (1982) states that Nomeus is able to tolerate 10 times the quantity of venom that kills other fishes.
Attains 39 cm. Adults appear to be demersal and are coloured a uniform dark brown . Circumglobal in warm waters.
255.7 Nomeus gronovii: 5 em (Transkei).
Genus Psenes Valenciennes, 1833
About 6 species; 5 in our area. Consideration of species
by Ahlstrom, Butler & Sumida, 1976. The appearance of
members of this genus changes considerably with growth;
the young are usually deep-bodied with marked colour patterns whereas the adults are slender and uniformly dark. All
allometric characters should be viewed with caution. The
genus is much in need of continued work.
KEY TO SPECIES
la Lower jaw teeth pointed or only slightly flattened,
similar to those in upper jaw; vertebrae 31-32 ... .. ..... ........... .. ... 2
Ib Lower jaw teeth long, compressed, contiguous,
very different from those in upper jaw; vertebrae 31-42 ..... ....... . 3
2a D IX-XI/I,23-28; A III,23-28; fine horizontal
lines along sides ... ..... .. .... ... ..... ...... ... ....... ....... .. P. cyanophrys
2b D X-XIIII ,17-21; A II-III,17-20; colour pattern
uniform brown ... .. .... ...... .. .............. .... ... .. .. .. .... .. P. whitelegg;;
3a D IX-XIIII-II,27-31; A III,26-31; body very soft;
bases of median fins translucent; vertebrae 40-42 .. .... P. pellucidus
3b D IX-XI/I-II,18-24; A III,21-23 ; body not
particularly soft; bases of median fins not
translucent; vertebrae 31-36 ............. .... .. ................ .. ... ..... ... 4
4a LL 55-62; body depth 1.4-2.4 in SL; vertebrae 31 .. .. . P. arafurensis
4b LL 70-85; body depth 2.4-3.4 in SL; vertebrae 34-38 .. P. maculatus
255: NOMEIDAE (DRIFTFISHES)
255.8 Psenes arafurensis
Gunther, 1889
Banded driftfish
Balk-dryfvis
Psenes arafurensis Gunther, 1889: 13, PI. 2, Fig. G (Arafura Sea);
Haedrich, 1967: 88; 1972: 81' ; Ahlstrom et aI. , 1976: 365'. Psenesrotundus Smith, SFSA No. 854a* (200 fms off Dassen Id.). Parapsenes rotundus: Smith, 1949: 847. Psenes benardi: Rossignol & Blache, 1961: 384'
(Gulf of Guinea).
D X-XIII-II,18-22; A III ,21-23; P 18-20; LL 55-62; GR about
8+(16-18); vertebrae 31. Depth 1.4-2.4, head 2.2-3 .1. Body firm and compressed. P equals length of head. Teeth in lower jaw twice length of those
in upper.
Mottled or banded colour pattern in small fish; adults
uniform, almost black. Attains 23 cm . Atlantic, Pacific and
Indian oceans.
255_8 Psenes arafurensis: top: 23 em holotype of P. rotundus (off Dassen Id.);
bottom: 3 em early juvenile (after Ahlstrom et al., 1976).
255.9 Psenes cyanophrys
Valenciennes, 1833
Freckled driftfish
Gevlekte dryfvis
Psenes cyanophrys Valenciennes, in Cuv. & Val., 1833: 260, PI. 265
(New Ireland); Smith, SFSA No. 854; 1949: 847; Haedrich, 1967: 87; 1972:
82; Ahlstrom et aI., 1976: 371'. Psenes fuscus Guichenot, 1866: 138
(Madagascar).
D IX-XIII,23-28; A III,23-28; P 17-20; LL 60-70; GR about 8+(18-21);
vertebrae 31. Depth 1.8-2.4, head 2.4-3.5. Body firm, deep and compressed; eye small, usually less than snout. P equal to or less than head . Teeth
in both jaws small and pointed, not laterally flattened .
Numerous dark horizontal lines on sides. Attains 20 cm,
but only immature specimens known. Atlantic, Pacific and
Indian oceans.
849
1966: 132'; Parin& Fedoryako, 1981'.
D IX-XIIII,24-28; A I-II,24-29; P 19-24; GR about 8+(15-19); vertebrae 41. Depth 2.6-4.8; head 2.6-4.0. Small conical teeth similar in both
jaws. V greatly expanded in juveniles. Fin spines weak.
Juveniles with striking dark blue mottlings over a whitish
or silvery base; V black. Juveniles associate with the pelagic
siphonophore Physalia and have been observed to feed on
the stinging tentacles, but they also eat chaetognaths and
other pelagic invertebrates (crustaceans, molluscs and
polychaets). Jenkins (1982) states that Nomeus is able to tolerate 10 times the quantity of venom that kills other fishes.
Attains 39 cm. Adults appear to be demersal and are coloured a uniform dark brown . Circumglobal in warm waters.
255.7 Nomeus gronovii: 5 em (Transkei).
Genus Psenes Valenciennes, 1833
About 6 species; 5 in our area. Consideration of species
by Ahlstrom, Butler & Sumida, 1976. The appearance of
members of this genus changes considerably with growth;
the young are usually deep-bodied with marked colour patterns whereas the adults are slender and uniformly dark. All
allometric characters should be viewed with caution. The
genus is much in need of continued work.
KEY TO SPECIES
la Lower jaw teeth pointed or only slightly flattened,
similar to those in upper jaw; vertebrae 31-32 ... .. ..... ........... .. ... 2
Ib Lower jaw teeth long, compressed, contiguous,
very different from those in upper jaw; vertebrae 31-42 ..... ....... . 3
2a D IX-XI/I,23-28; A III,23-28; fine horizontal
lines along sides ... ..... .. .... ... ..... ...... ... ....... ....... .. P. cyanophrys
2b D X-XIIII ,17-21; A II-III,17-20; colour pattern
uniform brown ... .. .... ...... .. .............. .... ... .. .. .. .... .. P. whitelegg;;
3a D IX-XIIII-II,27-31; A III,26-31; body very soft;
bases of median fins translucent; vertebrae 40-42 .. .... P. pellucidus
3b D IX-XI/I-II,18-24; A III,21-23 ; body not
particularly soft; bases of median fins not
translucent; vertebrae 31-36 ............. .... .. ................ .. ... ..... ... 4
4a LL 55-62; body depth 1.4-2.4 in SL; vertebrae 31 .. .. . P. arafurensis
4b LL 70-85; body depth 2.4-3.4 in SL; vertebrae 34-38 .. P. maculatus
255: NOMEIDAE (DRIFTFISHES)
255.8 Psenes arafurensis
Gunther, 1889
Banded driftfish
Balk-dryfvis
Psenes arafurensis Gunther, 1889: 13, PI. 2, Fig. G (Arafura Sea);
Haedrich, 1967: 88; 1972: 81' ; Ahlstrom et aI. , 1976: 365'. Psenesrotundus Smith, SFSA No. 854a* (200 fms off Dassen Id.). Parapsenes rotundus: Smith, 1949: 847. Psenes benardi: Rossignol & Blache, 1961: 384'
(Gulf of Guinea).
D X-XIII-II,18-22; A III ,21-23; P 18-20; LL 55-62; GR about
8+(16-18); vertebrae 31. Depth 1.4-2.4, head 2.2-3 .1. Body firm and compressed. P equals length of head. Teeth in lower jaw twice length of those
in upper.
Mottled or banded colour pattern in small fish; adults
uniform, almost black. Attains 23 cm . Atlantic, Pacific and
Indian oceans.
255_8 Psenes arafurensis: top: 23 em holotype of P. rotundus (off Dassen Id.);
bottom: 3 em early juvenile (after Ahlstrom et al., 1976).
255.9 Psenes cyanophrys
Valenciennes, 1833
Freckled driftfish
Gevlekte dryfvis
Psenes cyanophrys Valenciennes, in Cuv. & Val., 1833: 260, PI. 265
(New Ireland); Smith, SFSA No. 854; 1949: 847; Haedrich, 1967: 87; 1972:
82; Ahlstrom et aI., 1976: 371'. Psenes fuscus Guichenot, 1866: 138
(Madagascar).
D IX-XIII,23-28; A III,23-28; P 17-20; LL 60-70; GR about 8+(18-21);
vertebrae 31. Depth 1.8-2.4, head 2.4-3.5. Body firm, deep and compressed; eye small, usually less than snout. P equal to or less than head . Teeth
in both jaws small and pointed, not laterally flattened .
Numerous dark horizontal lines on sides. Attains 20 cm,
but only immature specimens known. Atlantic, Pacific and
Indian oceans.
849