New insights into the relationship of the genus Episemion
New insights into the relationship of the genus Episemion
The genus Episemion was described in 1987 based by five specimens found by Peter Wagner and Roland Wendel in 1986 and by Radda & Pürzl in 1987.
Thus far only one species in the Genus has been described, E. callipteron Radda & Pürzl, 1987 from a small range that covers northwestern Gabon and southeastern Equatorial Guinea.
A slightly different form with an aberrant color pattern was found in Edoum in Nordgabun on the border with Gabon in south
Equatorial Guinea.
Radda and Pürzl wrote in their introduction that the referring this species to a specific Genus was problematic.
When comparing the dorsal and anal ray values and the position of the dorsal to the anal with all known subgenera, nothing matched.
Only a few Nothobranchius species have the similar values.
The tail fin shape is striking and only shared with Fundulosoma.
Drawing and coloring pattern correspond rather that of the genus Epiplatys
The diagnostic for deciding referral of the Genus name to either the Aplocheilinae or the Nothobranchiinae per Parenti (1981) are these criteria:
1. Rear vomer area wide at Epiplatys, very narrow in Aphyosemion
2. Epipleural ribs unharmed
Epiplatys (Fig. 1 top right), feared at
Aphyosemion (Fig. 1 bottom right)
3. Upper Hypuralia shared with Epiplatys,
undivided at Aphyosemion
4. Absence (Epiplatys) or presence
(Aphyosemion) of curved processes
on the fourth epibranchialia.
5. High (Epiplatys) or low
Chromosome number (Aphyosemion)
1 - 4 are only for skeletal preparations
determine. Radda & Pürzl had only 5
Animals available as types should be available.
That's why they could meet those criteria
to not confirm. Episemion was provisional by the authors
described as a subgenus of Epiplatys.
In investigations of the relationship
a strange representative of the
Aplocheilidae (Fundulopanchax powelli),
caught in the western Niger Delta
the author has reviewed many features,
around Aphyosemion and Fundulopanchax
to be able to distinguish (Van der
Zee & Wildekamp, 1995).
In these studies are also EpiplatysArten
and Episemion callipteron
Service.
It turned out that Epiplatys and
Episemion have very little in common.
These results were however in the F.
powelli description not published and
are therefore presented here.
skeleton
Rear Vomer area
The vomer (a tiny bone on the
Underside of the skull) is at Episemion
narrow, just like Aphyosemion.
Epipleural ribs
furrowed
Head lower base / mandible
To determine if preserved specimens
belong to Epiplatys or Aphyosemion,
you only need the bottom of the head
to look at. Epiplatys shows a head bottom,
at the transition from the gill cover to the lower jaw between
eyes wide apart (Figure 4).
Aphyosemion and relatives show here
parallel pattern (Fig. 5).
Head top: Frontal system
The neuromasts are found on the top of the head near the mouth.
Other than the E. sexfasciatus species group, all Epiplatys species have the two front neuromasts in a single dimple,
(Fig. b) while all Aphyosemion, Fundulopanchax, and Nothobranchius and closely related fish have two dimples, each with single neuromast. (Fig a). Clausen noted by 1967 that the former "Roloffia" clade (Archaphyosemion, Scriptaphyosemion and Callopanchax), all have a single dimple (Clausen, 1967).
Also other criteria that I examined
showed that "Roloffia" and
Epiplatys shared several characteristics
who have not a single representative of
Aplocheilidae shares with you ("synapomorphies").
The close relationship of Epiplatys
and "Roloffia" was also examined by DNA
proven (Murphy & al.,
1999).
Criteria 4 and 5 are unfortunately with Episemion
not yet examined.
Although Parenti's work is a milestone
in the classification of the tooth carp should, should
not to mention that you are inside
a species group only very little material
has examined. That's why the results
often not very reliable when it
around the lower taxonomic units
is.
