Notes on the Systematic Status of the Eels Neenchelys and Myroconger 
Gareth J. Nelson 1 
Neenchelys 
Bohlke (I960) suggested that eels of the 
genus Neenchelys possibly have overlapping 
branchiostegal rays and that, if they did, they 
should be assigned to the family Ophichthidae. 
Nelson (1966^) described the osteology of 
Neenchelys buitendijki, confirming the presence 
of overlapping branchiostegal rays, and for this 
and other reasons referred the genus Neenchelys 
to the family Ophichthidae, subfamily Eche- 
linae. The present report, based on an ex- 
amination of the holotype of Neenchelys micro- 
tret us, confirms the presence of overlapping 
branchiostegal rays in the type species of Neen- 
chelys. Like those of N. buitendijki (Nelson, 
1966a, fig. 2 A), those of N. microtretus in- 
clude six rays articulating with the dorsal por- 
tion of the ceratohyal and more than 25 others 
widely overlapping in the midline. 
Myroconger 
This genus and the family it represents ap- 
parently are known only from the holotype of 
Myroconger compressus. The specimen had 
been partly dissected, leaving the gill arches 
exposed, which allowed the following observa- 
tions to be made: third and fourth upper 
pharyngeal tooth plates separate; first and sec- 
ond pharyngobranchials absent, the third sup- 
porting the tooth plates; basibranchials absent; 
independent rodlike hypobranchials in arches 
one-three, those of the third cartilaginous; 
fourth ceratobranchials not extended anteriorly, 
not separating the third arches of either side; 
fifth ceratobranchials apparently absent; ventral 
parts of the arches not meeting in the midline. 
Myroconger has the frontal bones separated 
by a suture and therefore belongs to the anguil- 
loid lineage of Regan (1912), including the 
Heterenchelidae, Anguillidae, Moringuidae, 
1 Department of Paleozoology, Swedish Museum of 
Natural History, Stockholm 50, Sweden. Manuscript 
received January 20, 1967. Present address: Ameri- 
can Museum of Natural History, New York, N.Y. 
Xenocongridae, Dysomminidae, and Muraeni- 
dae (Nelson, 19 66b). In completely lacking 
basibranchials, the arches of Myroconger differ 
from those of Heterenchelys, Anguilla, and 
Moringua, but resemble those of xenocongrids, 
Dysommina, and muraenids. In lacking a second 
pharyngobranchial they are unlike xenocon- 
grids, but resemble Dysommina and muraenids. 
Like that of Dysommina the fourth arch of 
Myroconger is not appreciably enlarged and 
"pharyngeal jaws” like those of muraenids do 
not occur. Thus, the arches of Myroconger are 
most like those of Dysommina. The most nota- 
ble differences include the presence in Myro- 
conger of third hypobranchials (a primitive 
feature) and the apparent absence of fifth 
ceratobranchials (an advanced one). 
What could be learned of the pharyngeal 
musculature also suggests a relationship with 
the more advanced eels of the anguilloid lineage, 
for a subpharyngealis occurs, as it does at least 
in Moringua, Kaupichthys, and muraenids, and 
retractor muscles have a small area of origin on 
the vertebral column, foreshadowing the large 
area of origin in some muraenids (Nelson, 
1967). 
These observations of Myroconger complete 
a review of gill arch structure for the families 
of anguilloid eels (Nelson, 1966b) . Within 
this group, on the basis of gill arch structure 
there seem to be three main lines of specializa- 
tion, each characterized by reduction of the gill 
arch skeleton: one leads toward the Morin- 
guidae, another toward the Muraenidae, the 
other toward the Cyemidae. If the anguilloid 
eels are given the status of a suborder, these 
lines of specialization could be given the status 
of superfamilies. However, on the basis of gill 
arch structure alone it is difficult to distinguish 
between generalized members of these different 
lines, or to decide which if any Recent forms 
can be considered generalized muraenoids. 
Consequently, the following synopsis is offered 
more as a working hypothesis than as a final 
classification: 
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