Preliminary Investigations on the Evolution of the
Tribe Electronini (Myctophiformes, Myctophidae)
P. Alexander Rulley
South African Museum, Cape Town, Republic of South Africa
Introduction
Lanternfishes are the most speciose family of oceanic teleosts [1].
Stiassny [2] has provided the most recent generic analysis. More than 35
myctophid species are known to occur in the Southern Ocean [3]. They are
distributed offshore of the continental shelf break and form the dominant
component of mesope1agic fish biomass in the Southern Ocean [4]. A
cladogram for Southern Ocean myctophids is lacking, but there is reason
to suspect that speciation in this region arose through a series of
vicariance events [5-8].
Fossil myctophids, represented mainly by otoliths, are known from the
Eocene [9]. They are apparently absent from the Cretaceous [10]. Fossil
material further suggests that the family may have approached its present
level of generic differentiation by the Late Miocene [10]. Both a coldwater [11] and a warm-water [5,6,12,13] origin for the family have been
postulated. It has been proposed that recent Southern Ocean species of
Protomyctophum, Electrona and Gymnoscopelus represent derivatives of
an Eocene fauna that lived in high latitudes of the Pacific sector; that
vicariance events were responsible for isolating populations of this high
latitude fauna; and that modem Southern Ocean species appeared during
the pronounced cooling periods of the Pliocene and Pleistocene [6].
This paper addresses the hypothesis in greater detail. It attempts to
resolve the evolution of one of the main groups of Southern Ocean
lanternfishes, the tribe Electronini [Krefftichthys, Protomyctophum
(Protomyctophum), Protomyctophum (Hierops), Electrona, Metelectrona].
Material and Methods
Biogeographic data were derived from two sources: (1) Cruise WH-1976:
FFS "Walther Herwig" [14]: 40916 specimens (63 species) from 39
stations between 80 and 2 650 m (MATRIX-I); and (2) Cruise ANT
XIV/2: RS "Polarstern" [4]: 16 290 specimens (11 species) from 17
G. di Prisco, E. Pisano, A. Clarke (Eds)
Fishes of Antarctica. A biological overview
© Springer-Verlag Italia 1998
Tribe Electronini (Myctophiformes, Myctophidae)
P. Alexander Rulley
South African Museum, Cape Town, Republic of South Africa
Introduction
Lanternfishes are the most speciose family of oceanic teleosts [1].
Stiassny [2] has provided the most recent generic analysis. More than 35
myctophid species are known to occur in the Southern Ocean [3]. They are
distributed offshore of the continental shelf break and form the dominant
component of mesope1agic fish biomass in the Southern Ocean [4]. A
cladogram for Southern Ocean myctophids is lacking, but there is reason
to suspect that speciation in this region arose through a series of
vicariance events [5-8].
Fossil myctophids, represented mainly by otoliths, are known from the
Eocene [9]. They are apparently absent from the Cretaceous [10]. Fossil
material further suggests that the family may have approached its present
level of generic differentiation by the Late Miocene [10]. Both a coldwater [11] and a warm-water [5,6,12,13] origin for the family have been
postulated. It has been proposed that recent Southern Ocean species of
Protomyctophum, Electrona and Gymnoscopelus represent derivatives of
an Eocene fauna that lived in high latitudes of the Pacific sector; that
vicariance events were responsible for isolating populations of this high
latitude fauna; and that modem Southern Ocean species appeared during
the pronounced cooling periods of the Pliocene and Pleistocene [6].
This paper addresses the hypothesis in greater detail. It attempts to
resolve the evolution of one of the main groups of Southern Ocean
lanternfishes, the tribe Electronini [Krefftichthys, Protomyctophum
(Protomyctophum), Protomyctophum (Hierops), Electrona, Metelectrona].
Material and Methods
Biogeographic data were derived from two sources: (1) Cruise WH-1976:
FFS "Walther Herwig" [14]: 40916 specimens (63 species) from 39
stations between 80 and 2 650 m (MATRIX-I); and (2) Cruise ANT
XIV/2: RS "Polarstern" [4]: 16 290 specimens (11 species) from 17
G. di Prisco, E. Pisano, A. Clarke (Eds)
Fishes of Antarctica. A biological overview
© Springer-Verlag Italia 1998