REVIEW APHYOSEMION OGOENSE

 

The superspecies Aphyosemion ogoense, a systematic review, together with the description of hypothetical patterns of speciation.

 

Jean H. Huber*

 

* Ichtyologie, Muséum national d'Histoire naturelle, 43 rue Cuvier, 75231 Paris Cedex 05, France.

 

 

I. The southern forest area of the Du-Chaillu uplands in the Congo; the history of fish collecting trips there.

 

The theoretical study of the biogeography of the southern area of the Du-Chaillu Massif in the Congo immediately points to the area's important part in the processes of speciation. The presence together of primary rain-forest and hill formations indicates the possibility of considerable separation of species in the genus Aphyosemion. The fork, which is formed by the coastal plain in the west and the Congo basin in the east, and held together by the River Niari, forms an additional element to the pressure of competition and thus to possible speciation. This is confirmed by the actual facts, because the region of the southern Du-Chaillu is inhabited by the largest number of Cyprinodonts known within the whole distribution area: 13 taxa of Aphyosemion, 1 still unsatisfactorily defined Epiplatys species from the E.multifasciatus group, and 3 Procatopodins: "Hypsopanchax" zebra and "H." catenatus together with P. terveri Huber 1981. on the northern border with Gabon.

From a historical point of view, the interest in this region became apparent through the collecting of killies in three stages:

1) The fish collected by the French colonial administrator A. Baudon at the end of the 1920s. These fish were examined by Pellegrin and led to the discovery of a large number of species. Some of these are now considered to be separate species, but at that time they were grouped together. For example, A. ogoense (1930) and A. louessense (1931) were described as varieties of A. lujae.

2) During the 1960s, the first aquarium populations were imported, thanks to the efforts of BRICHARD and LAMBERT; The first systemic problems appeared in connection with the identification of a fish found about 200 km north of Brazzaville. This fish was at one time called "striatum", and at another time "lujae". Then there was another fish, caught near Mindouli, which was named "louessense". The correct name of the first fish is Aphyosemion ogoense, as WILDEKAMP (1976), LAMBERT (1976) and RADDA & HUBER (1977) have shown. As for the second fish, I have been able to demonstrate that it is a separate and new species: A. zygaima HUBER (1981) loc. J.H. 175.

3) Lastly, in 1978, 79 and 80, there have occurred 5 expeditions by BUYTAERT, WACHTERS, PÜRZL and HOFFMAN, and the author, who was allowed to bring back numerous living populations and to discover new species. For this reason it seems to me necessary, to put together all the information we now have, and to examine again the latest fish alongside the fish collected by BAUDON.

 

II. Definition of the Aphyosemion ogoense superspecies, limits of the study.

 

The concept of "superspecies" is here understood strictly in the sense of 'fish whose evolution goes back to one recent ancestry. The superspecies Aphyosemion ogoense consists of fish, which inhabit the southern area of the Du-Chaillu Massif. They are species of medium size and have average meristic characters (Dm= 12; Am = 16; D/A = +6 to +7). In the caudal fin there is often an asymmetrical colour pattern, i.e. a red band which is marginal above and submarginal below, and a yellow or blue band which is conversely submarginal above and marginal below. The fish have a karyotype with a large number of chromosomes, which are metacentric and of average size.

The following species belong to the superspecies Aphyosemion ogoense: Aphyosemion ogoense, louessense, thysi, schluppi, wachtersi, buytaerti, pyrophore, caudofasciatum, ottogartneri and mikeae, this being the order in which they have been described.

 

The superspecies Aphyosemion ogoense in Gabon and central Congo does not include:

1. Species of the same group which inhabit the coastal plain: Aphyosemion striatum, microphtalmum and related species; these have a rather more slender body, and their chromosome and D, A and D/A numbers are rather smaller.

2. Species from the Cameroons and Gabon, which probably belong to the same group or come between it and the A. elegans group: A.wildekampi and the closely related A.punctatum.

3. Species from different groups, of similar shape, but which differ in karyotype and in having a symmetrical caudal pattern: A. coeleste, ocellatum in the north and west, A. zygaima, labarrei in the south.

4. Species from groups with different morphology, but which inhabit the Congo uplands: the various components of the A. elegans group.

 

Map of the Batéké uplands, also known as the southern Du-Chaillu Massif

in the People's Republic of Congo (Congo Brazzaville).

Locations and the distribution areas of the fish and groups of fish dealt with in this article are shown.

 

 

III. The components of the superspecies Aphyosemion ogoense.

 

To make it easier to understand the text, the reader should refer to the map which shows the locations of the following collecting trips:

- W.WACHTERS and J.BUYTAERT 1978 (locations RPC 1 to 33)

- J.H.HUBER, 1978 (locations JH 158 to 175)

- J.BUYTAERT, 1979 (locations RPC 201 to 207)

- J.H.HUBER, 1979 (locations JH 212 to 215)

- E.PÜRZL and O.HOFMANN, 1980 (Locations GHP 301 to 329)

 

Atlas of the French Colonies, Congo (South) Map 1899, scale 1: 3,000,000

French Colonial Atlas, French Equatorial Africa, Map 1929, 1: 6,500,000

 

The two maps available to PELLEGRIN in 1929 and 1930. Note on the left map the false position and the inexact lengthening of the Ogowe and on the right the footpaths used by M.BAUDON on safari.

 

 

1. Aphyosemion ogoense (PELLEGRIN, 1930)

 

PELLEGRIN described Haplochilus lujae var. ogoense from two groups of syntypes, which came from the Léconi or Lécéni River (M.N.H.N. No. 29-240) and from the La Passa (M.N.H.N. No. 25-241), both situated in the Upper Ogooué Province. If we examine the maps which were available to Pellegrin in 1930, and which are reproduced below, we will see considerable inaccuracies regarding the length of the River Ogowe, the source of the Léconi or Lécéni, the position of the River La Passa or M'Passa, and a shift in the position of the town Sibiti.

[As I reported in 1978, after I had seen the types again, A. lujae probably belongs to the elegans group. Although there are similarities of colour pattern with ogoense, the species seems to me completely different.]

It can therefore be stated that the syntypes from the River Lécéni (No.240) come from a locality further south and are in fact BRICHARD and LAMBERT's fish whereas the syntypes (No.241) from M'Passa, which came from a point near the Congo-Gabon border, are similar to Buytaert's fish (RPC 206-207). Examination of the well preserved types confirmed that the syntypes from the M'Passa are the same as Buytaert's fish with regard to morphology and colour pattern (slanting inner band).

After these lengthy investigations and the collecting of the specimens which correspond to types No. 240 from Vinza to Kindamba (JH 170 to 174), I decided to settle the nomenclature situation by keeping the name ogoense for Brichard's fish, which had had this name since the 60's, and to give a new name to the second group with the collection number 241.

Unfortunately RADDA took the opposite point of view. Working from PÜRZL's and HOFMANN's fish, collected in July 1980, which correspond to Buytaert's fish, he published shortly the following proposals (RADDA, October 1980):

1) The subspecies Aphyosemion ogoense ogoense which corresponds to No. 241, from the vicinity of Franceville (GHP 324, 325, 327, 328 and probably 323) as far as Bambama (RPC 206 to 207). A specimen from location 207, 16km south of Bambama, was given to the Paris Museum (M.N.H.N.) under the number 1980-1645, and another from location 206, close to Bambama, under the number 1980-1646.

2) The subspecies Aphyosemion ogoense ottogartneri, which corresponds to BRICHARD's fish, No.240, from Vinza to Kindamba (JH 170 to 174), and No.30-161 (M.N.H.N., from the River Lébagny, collector BAUDON)

 

Since we are dealing with two equivalent groups of syntypes, these proposals are valid; nevertheless, following the rules of zoological nomenclature (Article 74), a lectotype and paralectotypes should have been named.

I am therefore rectifying this omission by naming as lectotype of Aphyosemion ogoense sensu stricto the specimen in the Museum National d'Histoire de Paris attached to the label No. 29-241. The other specimens in this group are the paralectotypes. At the same time, I should like to apologise to the reader and to scientists for having published the new name plagitaenium (HUBER, 1980: 41, nomen nudum). I should not have done this, but my good faith cannot be questioned, and every interested person had been informed of my intentions beforehand. The true ogoense has the following karyotype: n = 17; A = 28. Karyotype of A. ottogartneri is: n = 20; A = 38 (SCHEEL, 1981).

Although the nomenclature is now clear, the systematics are still far from being sorted out, and we shall have to study the relationship between ottogartneri and the provisional "louessense" (RPC 31, 32, 33; JH 168, M.N.H.N. 30-146 from the River Loyo). We shall also have to look at the development in the colour pattern of aquarium specimens in the F1 and F2 generations [Wild fish from location JH 169 have a red longitudinal band and a few scattered spots. In the F1 generation progeny this had changed: now there were 4 red horizontal lines, as in ottogartneri] and at the special case of the western population JH 212, using our knowledge of species on the edge of the group's distribution area and on the chain of morphs in the historical development of the genus Aphyosemion (see Section IV) .

The distribution of ogoense and ottogartneri appears to be north-east within the superspecies; specimens in the museum of Tervuren (Belgium) were reported from the Congo, 200km north of Brazzaville, and this was confirmed by LAMBERT (see above). However, I am doubtful whether these fish come from that area, because the area around the banks of the Congo near the Batéké uplands is very dry terrain, where only members of the A. elegans group are to be found.

 

2. Aphyosemion louessense (PELLEGRIN, 1931)

 

Pellegrin also described louessense as a variety of lujae, again from fish from several collecting trips. Unfortunately, he named as holotype No 31-126 from the River Louessé, a single female, which is badly preserved and shows no colouration. He most probably described the colouration of the species from fish collected on a different occasion (No 31-145), paratypes, which come from the River Lali near Sibiti: a rather long orange longitudinal band on the rear part of the body. This characteristic colouring can be found again in the populations JH 166, 167 and RPC 24, 25. This persuaded RADDA and HUBER (1978) to propose the name A.louessense for these populations. Two factors, however, should make us quite cautious.

First there are transitional forms between ogoense/ottogartneri (3 to 4 longitudinal lines) and "louessense" (one longitudinal band), as has been described above. Many fish from one population have only a few scattered spots. Moreover, among the paratypes of louessense (No 31-145), there are specimens in which the longitudinal band is interrupted by lines of spots. The same is true of the specimens No 130-146 from the River Loyo).

And then PELLEGRIN found ogoense and "louessense" together, when he was studying collected fish from the River Lali, a tributary of the Louessé.

All these suggest that ogoense/ottogartneri and louessense (as in the paratypes) represent a single species with a variable colour pattern.

The second uncertainty comes from the holotype of louessense, whose colour pattern is still unknown. There are reasons for thinking that the holotype differs from the paratypes of louessense: more than once PELLEGRIN points out that louessense occurs sympatrically with ogoense in its western locations. But that "ogoense" is nothing but pyrophore, which is characterised by longitudinal stripes and vertical bars behind. The information on the location reads: "No 31- 72, Upper Louessé, Kouilou". The fish occurs there sympatrically with coeleste (then called cameronense; this is the first report of that species), with Epiplatys aff. multifasciatus (called sexfasciatus) and also with "No 31-124 and 125, Louessé. Now, in the north-western distribution areas, pyrophore and "louessense" (as in the paratypes) cannot live sympatrically. They are only colour variants, the forms are too closely related, they would interbreed. On the other hand, there is in the same area another form with a slightly different morphology but with a very different karyotype, which allows them to live together. This fish is schluppi, which has a few fairly large spots along the side of the body; this may have been the original cause of the confusion.

But we cannot ignore the hypothesis, that the fish, which were supposed to have been caught in the upper Louessé, and which correspond to the holotype, could have the same colour pattern as the fish from Sibiti and correspond to the paratypes; or also that they have a colour pattern, which is between this fish and that of the fish from Malinga (spec. JH 212). Then PELLEGRIN would be responsible for the original confusion. We are therefore left with two possible alternatives:

1. The provisional "louessense" of the present day is different from the true louessense, based on the holotype. The former fish will then be a variant of ogoense/ottogartneri, whereas the latter fish, coming from the River Louessé to the north-west of Sibiti, will be the fish which has the junior synonym of schluppi.

2. The holotype and the paratypes are identical. Then ottogartneri would be a junior synonym of louessense and schluppi would be valid.

 

For the time being, I would prefer to keep to the names used at present, until this region has been investigated. Unfortunately this area at the confluence of the upper Louessé is not provided with proper roads.

Finally I would like to point out that the provisional louessense has been observed in two morphs. The first (specimens from location RPC 33) is a sturdy. fish, and this makes it similar to ogoense. The fins are rounded, too. The second morph is attenuated (specimens from location RPC 24), more slender and could be closer to the type of thysi and schluppi. In this form the fins are more extended.

 

3. Aphyosemion pyrophore HUBER & RADDA, 1979

 

The third member of this group, Aphyosemion pyrophore, differs from A. ogoense not in its morphology, but in its colour pattern and karyotype (n = 19; A = 32 (SCHEEL, 1981)). The colour pattern consists of three elements: the front half of the body has four longitudinal stripes, the rear half of the body has vertical red bands, and the caudal fin has a flame pattern, with the bands on the edges being placed asymmetrically.

In 1978, A. pyrophore was discovered near Komono (locations JH 164, 165; RPC 18, 19, 20, 21, 22, 23), and thanks to A. BAUDON's collecting trips mentioned above, its distribution area can be extended considerably further to the north-west.

BAUDON's fish were identified by PELLEGRIN as ogoense. We should also include at this point fish No 31-144 from the River Lali, a tributary of the Louessé, and also PÜRZL and HOFMANN's fish (GHP 301, 323, 329).

A. pyrophore is the only component of the ogoense superspecies which exists in both colour phases, blue and yellow, as often happens with A.gardneri and A. cameronense. Moreover both can be found living sympatrically.

RADDA (1980) states, without giving reasons for his claim, that pyrophore is only a sub-species of ogoense. This possibility cannot be dismissed out of hand, and will have to be examined more closely, if crossing experiments are undertaken and produce fertile progeny to at least the F3 generation.

 

4. Aphyosemion caudofasciatum HUBER & RADDA, 1979

 

The fourth member of the ogoense group is very closely related to the previous species. It differs from it in its karyotype (n = 19; A = 38 (SCHEEL,1981)) and in the colour pattern of the caudal fin, which is unique among Aphyosemion species: a vertical black stripe on an ochre background in the centre of the fin. The species was originally discovered by WACHTERS and BUYTAERT near Zanaga in 1978 (RPC 27, 28, 29). In 1979 BUYTAERT collected more specimens further north (RPC 202, 205b), and this extended the known distribution area.

RADDA (1980) states, without giving any reason, that caudofasciatum is only a subspecies of ogoense. Even if their karyotypes are very similar, A.caudofasciatum is still the only member of the group with a completely different caudal pattern and a much shorter dorsal fin. Here too crossing experiments would be very desirable.

 

5. Aphyosemion spec. "Malinga"

 

This fish was collected a few kilometers north-west of Malinga, a Gabonese town near the Congo border. This is the most westerly location for the whole superspecies, and the fish is difficult to identify. Its morphology places it clearly alongside ogoense and the other species mentioned above. However, the colour pattern of wild fish is different. On its body the male has red transverse lines which run together and are more irregular than with thysi.

The female has a heavily spotted body, and there is a marked yellow colouration in the anal fin. Surprisingly however, the colour pattern of the males in the F1 generation is identical to that of "ottogartneri". The karyotype: n = 20; A = 38 (this must still be confirmed, as the number of usable preparations has not been sufficient). Its position is discussed in Section IV.

 

6. Aphyosemion thysi RADDA & HUBER, 1978

 

Compared with A. ogoense and its related fish discussed above, A. thysi and the following species, A. schluppi, are the first to show important differences: the body shape is more slender, dorsal and anal fins are shorter, and, most importantly, the number of chromosomes is much smaller (n = 14). These differences allow them to live sympatrically with the species mentioned above and also with A. wachtersi and A. buytaerti. In 1978, A. thysi was discovered in the neighbourhood of Mossendjo to the west of the Louessé (JH 158, 162 and RPC 6, 7, 9, 20, 22 (?)). It is characterised by a blue colour phase, in which the body has narrow red transversal bands, which are placed at irregular distances from each other. In addition there are considerable colour variations between the various populations. Within the superspecies its distribution area lies to the west.

 

7. Aphyosemion schluppi. RADDA & HUBER, 1978

 

A. schluppi was found near Zanaga and in other locations east of the Louessé.

It is very close to A. thysi in morphology and karyotype. In my opinion it represents the geographical eastern counterpart of thysi and the yellow colour phase (JH 163, RPC 29 (ho10type), RPC 28,27 and 18).

The colouring of the male is characterised by an ochre body. An interrupted line of large rust-coloured dots produces spots as far as the rear half of the body. Earlier in this paper I pointed out the danger of confusing this fish with the true A. louessense. Although it is not very colourful, A. schluppi is none the less interesting because of its orange fins and the great similarity between the males and females.

 

8. Aphyosemion wachtersi RADDA & HUBER, 1979

 

With A. wachtersi and the following fish A. buytaerti, the differences from A. ogoense are even clearer in their evolutionary developments. Dorsal and anal fins are even shorter, and, most importantly, the colour patterns differ considerably: an almost symmetrical colour pattern in the caudal fin, the presence of blue spots on the body, a rare characteristic in Aphyosemion, and a spotted rather than a flame-coloured caudal fin. Karyotype: n = 17; A = 34 (SCHEEL,1981).

A. wachtersi was discovered near Zanaga in 1978 (RPC 30). It also occurs further to the west near Komono (RPC 19). The species is characterised by a yellow colour phase with a blue-yellow iridescent body, which has an interrupted red line just below the centre lateral line. The two populations first discovered are distinguished by a slight colour variation in the anal fin: in RPC 30 the red band is near the body, whereas in RPC 19 it is submarginal. Finally, Buytaert caught fish from a population near Zanaga (RPC 202, 1979). It appears to be a very intermediate form. RADOA (1980) described the form RPC 19 as a subspecies, A. w. mikeae. I have discussed this problem with A.cameronense and A. mimbon.

 

9. Aphyosemion buytaerti RADDA & HUBER, 1978

 

To the north and east of Zanaga, A. wachtersi is probably replaced by the related A. buytaerti. The morphology is similar, the colour phase blue, the spots are blue, but the karyotype is different in the number of chromosome arms (n = 19; A = 29 (SCHEEL, 1981)). The colouration is more variable and in a few respects reminiscent of A. exigoideum. Unfortunately, in spite of intensive efforts by BUYTAERT and WACHTERS to find the fish in other places, A. buytaerti is known from only one location (RPC 28, 1978 and RPC 205a, 1979).

 

IV. The description of hypothetical patterns of speciation.

 

1. General phenomena

 

The genus Aphyosemion is characterised on the one hand by considerable uniformity of morphology and on the other hand by a variability in colour pattern and karyotype.

Many species live sympatrically and have selected very specialised ecological niches or roles - e.g. annualism or nocturnal habits. However. despite the variation in climate. seen in the differing vegetation. it is remarkable how slight the morphological variation is from geryi in the north to ferranti in the south, compared with the extent of the variation in karyotype. which limits the possibility of individual populations interbreeding. By the way. this is not generally the case. as the complete reverse is true with the North American Cyprinodontidae and African barbs.

The key to the evolution of the genus Aphyosemion is the sympatric presence of fish, which belong to different evolutionary lines. e.g. coeleste and thysi and also the presence together of relict species in a very limited distribution area together with a more recently evolved species. An example of this is schluppi or buytaerti living alongside caudofasciatum. Another factor is the allopatric (= mutually exclusive) presence of members of the same superspecies. They often follow each other from north to south, examples being coeleste-ocellatum-citrineipinnis or rectogoense-lamberti.

 

There is thus a fundamental two-sided phenomenon: sympatric presence and difference in form on the one hand, and allopatric presence and similarity in form on the other hand, as is found in the separation of the fauna zones between the coastal plain and the interior plateau. The same can be said of all western Africa (HUBER, 1978). In the area under discussion there is a further factor, namely the existence of the Congo basin in the east, which corresponds to the coastal plain in the west. The fauna zones which occupy these lowlands exert a double fork-shaped pressure on the fauna of the plateau. This results in a vertical division in the uplands as well, as is shown in the diagram on map.

 

2. Local phenomena

 

A thorough analysis of the distribution of Aphyosemion shows that:

 

a) In the coastal plain several very distinct superspecies live sympatrically, because a corridor arose along it, which formed a blind alley for the species which ventured into it.

b) In contrast to this, only a few superspecies live sympatrically on the inner plateau, and their distribution extends over a large area. Examples are gardneri, cameronense and exiguum. Their evolution appears to follow the basic principles of biology, in that they form a sufficiently variable gene pool to be able to adapt better to the differing conditions of environment or competition. As a result, the general phenotype is remarkably variable and occupies the greatest range of the limited area, where competition is at its greatest. Phenotypes (morphs, species) occur here which I have described as frontier phenotypes (HUBER, 1980).

A frontier species has a manifestly identical morphology and a karyotype which is similar to the species from which it is derived. But genetic changes have resulted in a variation in the colour pattern, sometimes accompanied by reproductive isolating mechanisms. The frontier species meets a competing superspecies, which in its turn has a corresponding frontier form.

At this point it should be stressed that this important development of the evolutionary line is a basic factor in the evolution of the Aphyosemion superspecies.

 

If we give a few examples, the reader will easily be able to make similar comparisons with any superspecies. Here, then, are some examples: mirabile, frontier species of the gardneri superspecies, with marmoratum (superspecies scheeli), celiae (calliurum) with cinnamomeum (gardneri), "etzeli" (liberiense) with geryi (geryi). It is even possible to have frontier phenotypes within the same group gabunense (striatum) with exigoideum (primigenium) (HUBER, 1981).

This concept can be generalised to other groups of Cyprinodontids. In the region under review ogoense and rectogoense are probably frontier species, and "Hypsopanchax" catenatus (RADDA, 1981) could have the same relationship to "H." zebra with Procatopus sp. (HUBER, 1981).

Moreover, in contrast to the coastal plain, the interior uplands point to centres of evolution, in which speciation is particularly intensive. We know of four at the present time:

a) the Guinea mountains and their spurs,

b) the Cameroon mountains,

c) the Ivindo basin in Gabon,

d) the south of the Du-Chaillu Massif, probably the most interesting area.

 

Seventeen Cyprinodont taxa have been described from this region, which on the whole is not very large, between Mossendjo in the west, Vinza .in the east, Franceville in the north, and Sibiti in the south. But when one examines the distribution frontiers, the following seems clear in relation to the ogoense superspecies:

a) the northern border is determined by the competition of species from other groups. The exact position of the border cannot be given.

b) Three other lowland frontiers have been formed. These are rather dry areas, in which these Aphyosemion are not to be found (the "fork" as described above).

From a systematic point of view, we can state that a chain of variable forms developed in an area the shape of three-quarters of a circle. This area has a "hard" northern nucleus, where speciation was intensive. Ample proof of this are the relict species there. The fish forming this chain are ogoense in the north, ottogartneri in the east, louessense in the south-west and spec. JH 212 in the north-west. This chain is continuous and no barrier separates from each other the various phenotypes which have been used in the description of the taxa given above. It has been shown too that around Kindamba there lives a population (ottogartneri sensu RADDA), which has only a few spots. Also, there are variations in the colour pattern of wild fish and the F1 progeny (JH spec. 212, JH 169). Then there are differences in colouration within one population (paratypes and comparable specimens of louessense). There are also whole populations of intermediate form (RPC 31,32, 33, JH 168). We can therefore advance the hypothesis, that this variable phenotype corresponds generally to the distribution and adaptation pattern of a single species.

 

Summary.

 

This first review of the ogoense superspecies has enabled us to state that:

a) 13 taxa of the genus Aphyosemion inhabit the southern area of the Du-Chaillu Massif in the Congo. 11 of these belong to the ogoense superspecles.

b) The superspecies shows a peculiar variability in colouration, but the fish can be grouped into three morphological types: the stockier forms: ogoense, "louessense" (as per the paratypes), pyrophore, caudofasciatum, ottogartneri, spec. "Malinga", 212, then the more slender forms: thysi and schluppi, and finally the small forms with blue spots: wachtersi and buytaerti.

c) Our knowledge of the area is reasonably satisfactory, with the exception of the Louessé river. Investigation of this valley would make it possible for us to clarify the problem of the true louessense and schluppi. It would also enable us to find out the relationship between spec. 212 and the eastern populations. We would then have the missing link in the chain.

d) The general pattern of the distribution and development of the genus Aphyosemion (HUBER, 1978) has a special application here because of the existence of a savannah belt of no great altitude, which surrounds three-quarters of this region.

e) Our knowledge of the genetics of this group is adequate. The basic number is 20 metacentric chromosomes, which makes these fish close to two other superspecies: striatum and probably wildekampi as well. The range of variation within this basic number is remarkable: n = 14 to 20.

f) Lastly and most importantly, we have a lot of work to do in the field of crossing experiments. You will see what I mean if we look back to the period 1973 - 1976. At that time European aquaria contained very interesting populations of the gardneri superspecies. Then other new species arrived, and gardneri was unfortunately scarcely studied any more, and the material which had been available disappeared.

Today the time has perhaps come, when the era of discovering new Aphyosemion species is so to speak almost over. Bearing this in mind, should we not work at extending our knowledge by means of crossing experiments within the ogoense group, of which we have so much material at the present time? I am convinced that this is an opportunity and a challenge to killifish enthusiasts. In this way we will be helped in our modest search for truth.

 

Paris, October 1980 and March 1981.

 

First published in French in Killi-Revue (KCF) in 1981

Translation into English by Peter Watkins for Killi-News (BKA), N° 204 (August 1982)

Also published in German in DKG Journal.

---

Addendum (2004): in order to clean up the damages originated with the herein mentioned nomen nudum Aphyosemion plagitaenium, it was decided to use the name plagitaenium for the description of a new species and a very different fish in another group.

Ref : Huber, J.H. 2004a. Description of a new Aphyosemion species from Congo, A. plagitaenium n.sp., exhibiting a probable intra-generic color convergence with oblique bars. Freshwater & Marine Aquarium (FAMA), 27 (12), (November 15): 70-74, 5 figs., 1 tab.

 

 

Additional reading of this author's publications ? Select any ONLINE article.