Rhabdalestes

Rhabdalestes Hoedeman, 1956

The species of this genus lack small conical teeth in the inner mandibular tooth row. The inner premaxillary teeth have rather numerous cuspids aligned on the same plane. Depending on species, and on individuals within species, the lateral line may be complete or incomplete. Body form is slender fusiform.

This genera is distinguished from all other Petersiini by the combination of the following characters::

  • two outer-row premaxillary teeth (four teeth total across both upper jaw elements);
  • inner dentary teeth absent;
  • 4½ scales in transverse scales between lateral line and dorsal fin origin.
  •  

    Synonyms

    Petersius Boulenger, 1899 (partim)

    Micralestes Boulenger, 1899 (partim)

    Micralestes (Rhabdalestes) Hoedeman, 1951

    Micralestes (Rhabdalestes) Hoedeman, 1956

    Hemigrammopetersius (Rhabdalestes) Géry, 1977

     

    Type species: Rhabdalestes tangensis

    Petersius tangensis Lönnberg, 1907 by original designation of Hoedeman, 1956.

     

    Currently, eight species are assigned to the genus Rhabdalestes.

     

    Key to species.

    1  35-37 scales along lateral line; 12-14 scales around the caudal peduncle.........................................................................2

        22-29 scales along lateral line; 10 scales around the caudal peduncle.............................................................................4

     

    2  Lateral line incomplete; 16 gill rakers on lower limb (ceratobranchial) of first gill arch............................................R. leleupi

        Lateral line complete; 14-15 gill rakers on lower limb (ceratobranchial) of first gill arch.......................................................3

     

    3  Well-marked band of melanophores present above anal fin; flanks with slignt dark band, more distinct backward................

        ...........................................................................................................................................................R. rhodesiensis

        No band of melanophores present above anal fin; flanks without dark band......................................................R. tangensis

     

    4  Lateral line incomplete..........................................................................................................................R. brevidorsalis

        Lateral line complete...................................................................................................................................................5

     

    5  12 gill rakers on lower limb (ceratobranchial) of first gill arch........................................................................R. maunensis

        13-19 gill rakers on lower limb (ceratobranchial) of first gill arch......................................................................................6

     

    6  17-19 gill rakers on lower limb (ceratobranchial) of first gill arch; 27-28 scales along lateral line.............................R. aeratis

        13-17 gill rakers on lower limb (ceratobranchial) of first gill arch; 24-27 scales along lateral line.........................................7

     

    7  4 (exceptionally 6) outer premaxillary teeth with 3-5 cusps; 13-17 anal fin branched rays; a black spot on the dorsal fin tip...

        .......................................................................................................................................................R. septentrionalis

        5-7 outer premaxillary teeth with 5 cusps; 18-19 (exceptionally 17) anal fin branched rays; no black spot on the dorsal fin tip

        .....................................................................................................................................................................R. yokai

     

    Discussion concerning the species to the genus Rhabdalestes (after Ibala Zamba & Vreven, 2008)

    Poll (1967a) and Paugy (1984) recognised seven Rhabdalestes species: R. eburneensis, R. leleupi, R. loennbergi, R. maunensis, R. rhodesiensis, R. septentrionalis and R. tangensis. According to Paugy (1990b) the character provided by Géry (1977) to diagnose R. loennbergi from R. septentrionalis, i.e. a black versus a hyaline point of the dorsal fin, was not convincing. Therefore, he synonymised R. loennbergi with R. septentrionalis. Rhabdalestes eburneensis was transferred to the genus Micralestes due to the presence of two inner mandibular teeth (Paugy, 1990b). In addition to the absence of two inner mandibular teeth, R. yokai is distinguished from R. eburneensis by having 25-26 pored lateral line scales (vs 27-29) and in missing a black spot at the top of the longest dorsal fin rays (vs spot present).

    Hemigrammopetersius brevidorsalis and Alestopetersius smykalai have been transferred to the genus Rhabdalestes by Paugy (1990b) and have therefore been included in the differential diagnosis of R. yokai. However, unfortunately Paugy (1990b) gave no detailed justification for this transfer. According to Stiassny & Schaefer (2005), the transfer of A. smykalai to the genus Rhabdalestes might have been motivated by the fact that this species is only known from the Niger whereas all other Alestopetersius are endemic to the Congo River basin. However, according to Stiassny & Schaefer (2005) R. smykalai has elongated dorsal and anal (the latter not confirmed by our observations) fins in males, features lacking in Rhabdalestes but typical for many Phenacogrammus, Nannopetersius and Alestopetersius. Therefore, Stiassny & Schaefer (2005) did not further compare their new species, i.e. R. aeratis, with R. smykalai.

    Despite the absence of inner mandibular teeth, Géry (1995) described and placed Micralestes ambiguus within the genus Micralestes, which is characterised by the presence of inner mandibular teeth, based on habitus and morphometric similarities to members of the M. argyrotaenia group. This seemingly natural group of tree species, i.e. M. argyrotaenia, M. congicus and M. lualabae, is characterised by relatively high number of 30-32 lateral line scales and a lateral band (Géry, 1995). The species name ambiguus, means changeable, uncertain, doubtful or of double meaning (Brown, 1956), and as such refers to the difficulty of placing the species in the proper genus (Géry, 1995). Despite the similarities of M. ambiguus with Rhabdalestes, the new species is readily distinguished from M. ambiguus by the fewer gill rakers on the lower limb of the first branchial arch (13-14 vs. 16) and a longer prepelvic distance (52.1-54.5 % SL vs. 46.6-50.6 % SL).

    The monotypic genus Virilia was described by Roberts (1967) based on an important thickening of the segments of the third unbranched anal-fin ray in males of the type species Phenacogrammus pabrensis. Paugy (1990b) however placed the species into Micralestes whereas Géry (1995) placed it into Rhabdalestes. According to Stiassny & Schaefer (2005) the placement of the species remains problematic and must await thorough phylogenetic analysis. Certainly other Rhabdalestes species, such as R. aeratis (see Stiassny & Schaefer, 2005), R. eburneensis (see Zanata & Vari, 2005) and R. septentrionalis (Paugy, 1990b) exhibit a similar modification and expansion of the male anal fin. Indeed, according to Zanata & Vari (2005) not only Rhabalestes (i.e. R. eburneensis, R. loennbergi, R. rhodesiensis and R. septentrionalis) and Virilia (i.e. V. pabrensis) but also the Hemigrammopetersius species examined (i.e. H. barnardi and H. intermedius) all are characterised by an anteroposterior thickened and distinctly curved third unbranched anal-fin ray (Zanata & Vari, 2005: characters 182 and 183). Rhabdalestes yokai is characterised by an elongation of the third unbranched anal-fin ray, i.e. compared to the first and the second one. However, whereas in P. pabrensis, and also for instance in R. aeratis, the first as well as the second unbranched anal-fin rays are small compared to the third one, in R. yokai the second one is of intermediate size between the small first one and the larger third one. Further, R. yokai lacks such an anteroposterior thickening (i.e. compared to the branched fin rays) and distinctly curving of this fin ray as found in P. pabrensis as well as R. aeratis. Regardless, in addition R. yokai can be readily distinguished from P. pabrensis by a higher number of outer premaxillary teeth (5-7 vs 4) and a complete lateral line with 25-26 tubes (vs. an incomplete lateral line with 6-10 tubes).

     

    Bibliography

  • Brown R.W., 1956. Composition of scientific words. Smithonian Institution Press, Washington and London, 882 p.
  • Géry J., 1977. Characoids of the World. Neptune City, NJ, TFH Publications, 672 p.
  • Géry J., 1995. Description of new or poorly known Alestinae (Teleostei, Characiformes, Alestidae) from Africa, with a note on the generic concept in the Alestinae. Aqua, Journal of Ichthyology and Aquatic Biology, 1: 37-64.
  • Hoedeman J.J., 1951. Studies on African characid fishes. I. The tribe Alestidi. Beaufortia, 1, 3: 1-8.
  • Hoedeman J.J., 1956. Aquariumvissen-encyclopoedie. De Bezige Bij, Amsterdam: 557-561.
  • Ibala Zamba A. & Vreven E.J., 2008. Rhabdalestes yokai (Characiformes: Alestidae), a new species from the Léfini and Sangha River basins (Congo River basin), Africa. Ichthyological Exploration of Freshwaters, 19, 4:377-384.
  • Paugy D., 1984. Characidae: 140-183. In Daget J., Gosse J.-P. & Thys van den Audenaerde D.F.E. (eds), Check-list of the freshwater fishes of Africa, Cloffa 1, Orstom Paris & MRAC Tervuren, 410 p.
  • Paugy D., 1990b. Note à propos des Petersiini (Teleostei: Characidae) d’Afrique occidentale. Ichthyological Exploration of Freshwaters, 1: 75-84.
  • Poll M., 1967a. Révision des Characidae nains africains. Annales du Musée royal de l’Afrique centrale, série in-8°, Sciences Zoologiques, 162 p.
  • Roberts T.R., 1967. Virilia, a new genus of sexually dimorphic characid fishes from West Africa, with remarks on characoids having an incomplete lateral line. Stanford Ichthyological Bulletin, 8, 4: 251-256.
  • Stiassny, M.L.J. & Schaefer S.A., 2005. Rhabdalestes aeratis, new species (Characiformes: Alestidae): first occurrence of the genus from the Middle Congo River basin. Ichthyological Exploration of Freshwaters, 16, 3: 271-278.
  • Zanata A.M. & Vari R.P., 2005. The family Alestidae (Ostariophysi, Characiformes); a phylogenetic analysis of a trans-Atlantic clade. Zoological Journal of the Linnean Society, 145: 1-144.
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    Rhabdalestes aeratis Stiassny & Schaefer, 2005

    rhabdalestes_aeratis_picture

    Type and type locality

    Rhabdalestes aeratis Stiassny & Schaefer, 2005: 273-275, fig. 1-3. Type locality: “Democratiec Republic of Congo: main channel outlet from Lake Tumba near Irebu, 0°35.84’S 17°46.96’E”. Holotype: AMNH 235767; paratypes: AMNH 235768.

     

    Common names

    Estonian: Pronksjas tintsalmler

     

    Description

    Diagnosis: body depth 3.7-4.3 and head length 3.88-4,20 in SL. Dental formula: [4/8 (upper jaw), 8/0 (lower jaw)]. Cuspids number: [3/3-5 (upper jaw), 3-5/0 (lower jaw). Dorsal fin: II,8. Anal fin: III,14-15. Gill rakers: 17-19. Scales: 27-28 (longitudinal line); 4½ (above lateral line). Lateral line complete with 27-28 tubes (see table below).

    Rhabdalestes aeratis: morphometric and meristic data.

    morphological_characters_raeratis

    Maximum reported size: 50.8 mm SL.

    Colour: base body coloration brown dorsalIy and laterally with highly reflective golden-bronze iridescence. Dorsum of head and body darkly pigmented, concentration of chromatophores along posterior scale margins. Chest and belly creamy brown. All fins dusky, with pigment concentrated along margins of fin rays and interspaces. Dorsal fin occasionally with pigment concentration at apical tip. Anal fin base with dark band along entire length of fin-ray insertion, becoming diffuse and lighter grey distally. Caudal fin dusky black, without pigment concentration along median fin rays.

    Affinities: distinguished from all putative congeners by having 17-19 gill rakers on the lower limb of the first arch (vs 11-17). Further distinguished from all congeners by the combination of a slender body, its depth contained 3.7-4.2 times in standard length, 14-15 branched anal-fin rays, 26-28 lateral-lines scales, all of which bear lateral-line canals, flanks with golden-bronze reflective coloration overlain by dark brown chromatophores, and dark midlateral pigmentation stripe absent. Rhabdalestes aeratis differs from R. leleupi, R. rhodesiensis, and R. tangensis in having fewer scales in the lateral line (27-28 vs 35-39). It differs from all other Rhabdalestes species, with the exception of R. maunensis, by an extremely slender body form (body depth 24-27% SL vs 28-33). Rhabdalestes aeratis is distinguished from R. maunensis by a greater number of gill rakers (17-19 vs 12) and fewer branched anal fin rays (14-15 vs 17). It differs from R. brevidorsalis, included in Rhabdalestes by Paugy (1990b), in having a complete lateral line with 27-28 pored scales (vs 6-7 pored scales) and a higher number of gill rakers (17-1 9 vs 11-13).

    Remarks: prior to the description of R. aeratis, the only Rhabdalestes species recorded from the Congo River basin was R. rhodesiensis from the Bangweulu-Luapula region of the upper Congo River.

     

    Distribution

    Currently known only from the type locality: Democratic Republic of Congo, main channel outlet from Lake Tumba near Irebu, 0°35.84'S 17°46.96'E. Collections were made during the rainy season (average October rainfall 200-220 mm) and rising water levels had already inundated surrounding swamp grasslands and lowland forest. Specimens were collected using cast nets from pirogues and were taken in the large, black water, main channel outlet of Lake Tumba close to the flooded shoreline near Irebu (see also Faunafri).

     

    IUCN assessment

    Rhabdalestes aeratis is only known from the type locality Lake Tumba at Irebu, Central Congo River basin. The species may be more widespread than is currently known. More information is needed on the species distribution before an assessment can be made.

    Major threats: none known.

     

    FishBase link

     

    Bibliography

  • Paugy D., 1990b. Note à propos des Petersiini (Teleostei: Characidae) d’Afrique occidentale. Ichthyological Exploration of Freshwaters, 1: 75-84.
  • Stiassny, M.L.J. & Schaefer S.A., 2005. Rhabdalestes aeratis, new species (Characiformes: Alestidae): first occurrence of the genus from the Middle Congo River basin. Ichthyological Exploration of Freshwaters, 16, 3: 271-278.
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    Rhabdalestes brevidorsalis (Pellegrin, 1921)

    rhabdalestes_brevidorsalis_picture

    Type and type locality

    Petersius brevidorsalis Pellegrin, 1921: 49-50. Type locality: “Fort-Crampel (Gribingui)”. Syntypes: MNHN 21-10.

     

    Synonyms

    Petersius brevidorsalis Pellegrin, 1921

    Hemigrammopetersius brevidorsalis Poll, 1945

    Rhabdalestes brevidorsalis Paugy, 1990

     

    Common names

    Estonian: Lühiuim-tintsalmler

    Hausa: Kawara (Nigeria)

     

    Description

    Diagnosis: body depth 3-3.2 (2.8-3) and head length 3.3-3.6 (3.3-3.5) in SL. Dental formula: [4/8 (upper jaw), 8/0 (lower jaw)], [type: 4/8 (upper jaw), 8/0 (lower jaw)]. Cuspids number: not indicated. Dorsal fin: II,8 (II,8). Anal fin: III,13-14 (III, 13-14). Gill rakers: 11-13 (11-13). Scales 25-26 + 2 (25) (longitudinal line); 4½ (above lateral line)/3½ (below lateral line) (4½/3½); 10 around caudal peduncle. Lateral line scales: 6-7 (7) tubes.

    Maximum reported size: 33 mm SL.

    Colour: a thin dark longitudinal line more marked at the back. Dorsal-fin tip blackish.

     

    Distribution

    Gribingui at Kaga Bandoro (ex Fort Crampel, Central Africa Republic) and Mayo-Kebbi (Cameroon), Chad basin (see also Faunafri).

     

    IUCN assessment

    The estimated EOO is less than 5,000 km² and AOO is less than 500 km², and it is restricted to two locations. Current information suggests no decline in habitat or distribution. Although the species has a restricted distribution it has no known major widespread threats and is found in very remote areas so is assessed as Least Concern.

    Major threats: remote area with no known major threats.

     

    FishBase link

     

    Bibliography

  • Lévêque C., Paugy D. & Teugels G.G., 1991. Annotated check-list of the freshwater fishes of the Nilo-sudan river basins, in Africa. Revue d'Hydrobiologie Tropicale, 24, 2: 131-154.
  • Paugy D., 1990b. Note à propos des Petersiini (Teleostei: Characidae) d’Afrique occidentale. Ichthyological Exploration of Freshwaters, 1: 75-84.
  • Paugy D., 2003. Alestidae: 236-282. In Paugy D., Lévêque C. & Teugels G.G. (eds). Faune des poissons d’eaux douces et saumâtres de l’Afrique de l’Ouest. IRD Éditions, Paris, MRAC, Tervuren, MNHN, Paris, collection Faune tropicale, 40, volume I, 800 p.
  • Pellegrin J., 1921. Poissons du Gribingui et de la M'poko recueillis par M. Baudon. Description d'un Characinidé nouveau. Bulletin de la Société Zoologique de France, 46: 47-50.
  • Poll M., 1945. Descriptions de Mormyridae et de Characidae nouveaux du Congo belge avec une étude du genre Stomatorhinus et des genres de Characidae nains africains. Revue de Zoologie et de Botanique Africaines, 39, 1: 36-77.
  • Poll M., 1967a. Révision des Characidae nains africains. Annales du Musée royal de l’Afrique centrale, série in-8°, Sciences Zoologiques, 162 p.
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    Rhabdalestes leleupi Poll, 1967

    rhabdalestes_leleupi_picture

    Type and type locality

    Rhabdalestes leleupi Poll, 1967: 130-132, fig. 28. Type locality: “Kenya, lake Jipe, Teita district”.Holotype: MRAC 153759.

     

    Synonyms

    Rhabdalestes leleupi Poll, 1967

    Hemigrammopetersius (Rhabdalestes) leleupi Géry, 1977

     

    Common names

    English: Pangani robber (Kenya)

    Estonian: Leleupi tintsalmler/Tanga tintsalmler

    Finnish: Tanganalesti

    German: Tangasalmler

    Swahili: Dagaa (Tanzania)

     

    Description

    Diagnosis: body depth 4 and head length 3.8 in SL. Dental formula: [4/8 (upper jaw), 11/0 (lower jaw)]. Cuspids number: [3/4-5 (upper jaw), 1-5/0 (lower jaw). Dorsal fin: II,8 located behind pelvic-fin insertion. Anal fin: III,17. Gill rakers: 16. Scales 37 + 2 (longitudinal line); 6½ (above lateral line)/3½-4½ (below lateral line); 12-13 around caudal peduncle. Lateral line scales: 33 tubes.

    Maximum reported size: 56 mm SL.

    Colour: an indistinct mid-lateral blackish band, silvery, a bit clearer at the back. Fins are greyish, the anal fin delicately edged with black.

    Affinities: this species is close to Rhabdalestes tangensis from Eastern Africa (Tanga River) of which it clearly differs for the sharpness of the caudal peduncle which is 1.8 times longer than depth ( versus 1.5), the high number of longitudinal line scales 37 + 2 (vs 35 + 2) and the low number of tubes: 33 (instead of a complete lateral line), the number of teeth of the lower jaw: 11 (vs 8) and the different sizes of the eye and the interorbital width.

    Holotype description

     

    Body depth 4, head length is 3.8 of the standard length. Head width is 2.15 of the head length. Short sub-rounded snout is, 4.15 of the head length, 1.6 of the eye diameter, 1.5 of the postorbital. Eye is 2.6 of the head length. Interorbital is 3.6 of the head length and 1.4 of the eye diameter.

    Sub-terminal mouth, with slightly prominent lower jaw. Four upper external teeth alternating with 8 upper internal teeth. A row of 11 lower teeth (no median internal teeth). A little number of cuspids, 3 for upper external teeth, from 4 to 5 for upper internal teeth, from 1 to 5 for lower teeth. The longest tooth of the upper jaw is the third internal one, in the lower jaw it is the second one.

    Dorsal fin II,8, non-filamentous, behind pelvic-fin insertion. Head length is 1.25 of the longest rays.

    Anal fin III,17, with anterior rays longer and stronger in mature male. Pectoral fin is 1.2 of the head length. Caudal fin is forked with sharp lobes. Caudal peduncle is 1.8 times longer than deep.

    Longitudinal line scales 37+2; transversal line scales 6½/3½-4½; scales around caudal peduncle 12-13. Lateral line shortened at the back, with 33 tubes.

    6 gill rakers on the lower limb of the first gill arch.

    Colour : an indistinct mid-lateral blackish band, silvery, a bit clearer at the back. Fins are greyish, anal fin delicately edged with black.

     

    Distribution

    Pangani River and Tanga region in East Africa (see also Faunafri).

     

    IUCN assessment

    The species has an estimated extent of occurrence <100 km² is restricted to a single location, the Nyumba ya Mungu lake and its outlet, and has suffered a significant population decline due to overfishing and deterioration of habitat. The causes of population decline are still ongoing.

    Major threats: over-fishing accompanied by use of illegal gears and methods. Increased siltation due to deforestation and agricultural practice. Land-based pollution especially from domestic and agricultural activities.

     

    FishBase link

     

    Bibliography

  • Eccles D.H., 1992. FAO species identification sheets for fishery purposes. Field guide to the freshwater fishes of Tanzania. Prepared and published with the support of the United Nations Development Programme (project URT/87/016), FAO, Rome, 145 p.
  • Poll M., 1967a. Révision des Characidae nains africains. Annales du Musée royal de l’Afrique centrale, série in-8°, Sciences Zoologiques, 162 p.
  • Seegers L., De Vos L. & Okeyo D.O., 2003. Annotated checklist of the freshwater fishes of Kenya (excluding the lacustrine haplochromines from Lake Victoria). Journal of East African Natural History, 92: 11-47.
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    Rhabdalestes maunensis (Fowler, 1935)

    rhabdalestes_maunensis_picture

    Type and type locality

    Petersius maunensis Fowler, 1935:259-260, fig. 5. Type locality: “Thamalakane River at Maun”. Holotype: ANSP 15276.

     

    Synonyms

    Petersius maunensis Fowler, 1935

    Alestes lateralis (non Boulenger, 1900) Jubb, 1963

    Rhabdalestes maunensis Poll, 1967

    Hemigrammopetersius (Rhabdalestes) maunensis Géry, 1977

     

    Common names

    Afrikaans: Mbala/Okavango Robber (Namibia), Slanke rower (South Africa)

    English: Okavango robber/Slender robber (global)

    Estonian: Okavango tintsalmler

     

    Description

    Diagnosis: body depth (5) and head length (3.4-3.65) in SL. Dental formula: [type: 8/0 (upper jaw), 8/0 (lower jaw)] (?). Cuspids number not indicated. Dorsal fin: (III,8) behind pelvic-fin insertion. Anal fin: (III,17). Gill rakers: (12). Scales: (28-29 + 2-3) (longitudinal line); 4½ (above lateral line)/3½ (below lateral line); (10) around caudal peduncle. Lateral line scales: 28-29 tubes.

    Maximum reported size: 49 mm SL.

    Colour: a mid-lateral black band, more visible at the back. Anal fin edged with black.

     

    Habitat and Ecology

    R. maunensis is a shoaling species that lives amongst vegetation in shallow water in rivers and flood plains. This species is rarely found in the main channel of the upper Zambezi river, patchily distributed on the floodplain but more common in small streams (Tweddle et al. 2004). It feeds on small aquatic insects and other invertebrates. A partial spawner breeding at high water (Skelton, 2001; Marshall, 2011).

     

    Distribution

    Cunene, Okavango, Upper Zambezi and Kafue River systems. A similar, possibly identical, species (R. rhodesiensis) occurs in the Zambian Congo system (Lakes Bangweulu and Mweru, and Luapula River) (see also Faunafri).

     

    IUCN assessment

    This species has a wide distribution, with no known major widespread threats. It is therefore listed as Least Concern.

    Major threats: none known.

     

    FishBase link

     

    Bibliography

  • Bell-Cross, G. & Minshull J.L., 1988. The fishes of Zimbabwe. National Museums and Monuments of Zimbabwe, Harare, Zimbabwe, 294 p.
  • Bruton M., Merron G. & Skelton P.H., 2018. Fishes of the Okavango Delta & Chobe River, Botswana. Struik Nature, Cape Town, 120 p.
  • Fowler H.W., 1935. Scientific results of the Vernay-Lang Kalahari expedition March to September 1930. The freshwater fishes. The Annals of the Transvaal Museum, 16, 2: 251-293.
  • Marshall B.E., 2011. The fishes of Zimbabwe and their biology. Smithiana Monographs n° 3, 290 p.
  • Poll M., 1967a. Révision des Characidae nains africains. Annales du Musée royal de l’Afrique centrale, série in-8°, Sciences Zoologiques, 162 p.
  • Skelton P., 2001. A Complete Guide to the Freshwater Fishes of Southern Africa. Second Edition. Struik Publishers, Cape Town, 395 p.
  • Tweddle D., Skelton P.H., van der Waal B.C.W., Bills I.R., Chilala A. & Lekoko O.T., 2004. Aquatic biodiversity survey for the “Four Corners” Transboundary Natural Resources Management Area. Final Report - July 2004. Report for African Wildlife Foundation, SAIAB Investigational Report, 71: xviii+202 p.
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    Rhabdalestes rhodesiensis (Ricardo-Bertram, 1943)

    rhabdalestes_rhodesiensis_picture

    Type and type locality

    Petersius rhodesiensis Ricardo-Bertram, 1943: 201. Type locality: “Chambezi River, lake Bangwelo”. Syntypes: BMNH 143.7.27:142-145.

     

    Synonyms

    Petersius rhodesiensis Ricardo-Bertram, 1943

    Micralestes (Rhabdalestes) tangensis rhodesiensis Hoedeman, 1951

    Rhabdalestes rhodesiensis Poll, 1967

    Hemigrammopetersius (Rhabdalestes) rhodesiensis Géry, 1977

     

    Common names

    English: Slender Robber (USA)

    Estonian: Sale tintsalmler

    Lwena: Mungumba (Angola)

     

    Description

    Diagnosis: body depth 3.9-4.6 (4-4.5) and head length 3.8-4.25 (4-4.25) in SL. Dental formula: [4-6/8-10 (upper jaw), 8-10/0 (lower jaw)], [type: 4-6/8 (upper jaw), 6-8/0 (lower jaw)]. Cuspids number: [3/3-5 (upper jaw), 1-5/0 (lower jaw)]. Dorsal fin: II,8 (II,8) behind pelvic-fin insertion. Anal fin: III,17-19 (III,16-17). Gill rakers: 14-15 (16-17). Scales 35-37 + 2 (longitudinal line) (33-36); 5½-6½ (above lateral line)/3½-4½ (below lateral line) (5½/3½); 13-14 around caudal peduncle. Lateral line scales: 35-38 tubes.

    Maximum reported size: 74 mm SL.

    Colour: a mid-lateral black band, more visible at the back. Anal fin bottom edged with black.

    Remark: possibly a synonym of R. maunensis (Skelton, 2001)

     

    Distribution

    Bangweulu-Luapula (Democratic Republic of the Congo and Zambia). Possibly present in the Kafue River system. Presence in southern Africa (upper Zambezi, Lake Kariba and the Kalomo River in Botswana) needs confirmation (see also Faunafri).

     

    IUCN assessment

    Although there are threats known in the region, the species is listed as Least Concern because of its relatively wide distribution and protection by the controlled fishing in the Luapula-Mweru system.

    Major threats: in the Katanga region, mining for cobalt, copper, tin, uranium, dams and the use of toxic plants for fishing and overfishing form threats in this region.

     

    FishBase link

     

    Bibliography

  • Ibala Zamba A. & Vreven E.J., 2008. Rhabdalestes yokai (Characiformes: Alestidae), a new species from the Léfini and Sangha River basins (Congo River basin), Africa. Ichthyological Exploration of Freshwaters, 19, 4:377-384.
  • Kapasa C.K. & Cowx I.G., 1991. Post-impoundment changes in the fish fauna of Lake Itezhi-tezhi, Zambia. Journal of Fish Biology, 39, 6:783-793.
  • Poll M., 1967a. Révision des Characidae nains africains. Annales du Musée royal de l’Afrique centrale, série in-8°, Sciences Zoologiques, 162 p.
  • Ricardo-Bertram C.K., 1943. The fishes of the Bangweulu region. Zoological Journal of the Linnean Society, 41: 183-217.
  • Skelton P., 2001. A Complete Guide to the Freshwater Fishes of Southern Africa. Second Edition. Struik Publishers, Cape Town, 395 p.
  • Stiassny, M.L.J. & Schaefer S.A., 2005. Rhabdalestes aeratis, new species (Characiformes: Alestidae): first occurrence of the genus from the Middle Congo River basin. Ichthyological Exploration of Freshwaters, 16, 3: 271-278.
  • Van Steenberge M., Vreven E. & Snoeks J., 2014. The fishes of the Upper Luapula area (Congo basin): a fauna of mixed origin. Ichthyological Exploration of Freshwater, 24, 4: 329-345.
  •  

     

    Rhabdalestes septentrionalis (Boulenger, 1911)

    rhabdalestes_septentrionalis_picture

    Types and type localities

    Petersius septentrionalis Boulenger, 1911: 373. Type locality: “Geba River at Bafata”. Syntypes: BMNH 1912.4.1:144-149.

    Petersius loennbergi Svenson, 1933: 57-59. Type locality: “Gambia River”. Syntypes: NRMS 10229.

    Petersius intermedius Blache & Miton, 1960: 102. Type locality: “Lac Tchad”. Syntypes: MNHN 59228.

     

    Synonyms

    Petersius septentrionalis Boulenger, 1911

    Hemigrammopetersius septentrionalis Myers, 1929

    Micralestes septentrionalis Hoedeman, 1951

    Micralestes (Micralestes) septentrionalis Hoedeman, 1959

    Rhabdalestes septentrionalis Poll, 1967

    Hemigrammopetersius intermedius Poll, 1967

    Rhabdalestes loennbergi Poll, 1967

    Hemigrammopetersius (Rhabdalestes) septentrionalis Géry, 1977

    Hemigrammopetersius (Rhabdalestes) loennbergi Géry, 1977

    Petersius loennbergi Paugy, 1990

    Petersius intermedius Paugy, 1990

     

    Common names

    Estonian: Kuldjoon-tintsalmler

    Finnish: Kultajuova-alesti

    German: Tschadsalmler

     

    Description

    Diagnosis: body depth 3.5-4.1 (3.5-3.75) and head length 3.3-3.8 (3.5-3.75) in SL. Dental formula: [4-6/8-10 (upper jaw), 8/0 (lower jaw)], [type: 4/8 (upper jaw), 8/0 (lower jaw)]. Cuspids number: [3-5/3-6 (upper jaw), 3-5/0 (lower jaw)]. Dorsal fin: II,8 (II,7) located at vertical through pelvic-fin insertion. Anal fin: III,15-17 (III,13-14). Gill rakers: 14-17 (12). Scales 24-27 + 2 (25-26) (lateral line); 4½ (above lateral line)/3½ (below lateral line) (4½/3½); 10 around caudal peduncle. Lateral line scales: 23-27 tubes.

    Maximum reported size: 54 mm SL.

    Colour: a mid-lateral black band, more visible at the back. Anal fin bottom edged with black.

     

    Distribution

    Occurs throughout most of Wertern African River basins: Chad, Niger, Benue, Mono, Volta, Pra, Comoe, Agnebi, Bandama, Konkoure, Kolente, Kaba, Sewa, Moa, Mano, Senegal, Gambia, Tomine, Geba, and Wouri (see also Faunafri).

     

    IUCN assessment

    This species has a wide distribution, with no known major widespread threats. It is therefore listed as Least Concern. It has also been assessed regionally as Least Concern for western Africa. It is estimated that less than 5 % of the species is found in the central Africa region, and has therefore been categorised as Not Applicable for this region.

    Major threats: oil extraction in Nigeria threatens local populations.

     

    FishBase link

     

    Bibliography

  • Blache J. & Miton F., 1960. Poissons nouveaux du bassin du Tchad et du bassin adjacent du Mayo-Kebbi. 1: Characoidei. Bulletin du Muséum national d’Histoire naturelle, Paris, 2, 32, 1: 100-107.
  • Lévêque C., Paugy D. & Teugels G.G., 1991. Annotated check-list of the freshwater fishes of the Nilo-sudan river basins, in Africa. Revue d'Hydrobiologie Tropicale, 24, 2: 131-154.
  • Lévêque C., Paugy D., Teugels G.G. & Romand R., 1989. Inventaire taxinomique et distribution des poissons d'eau douce des bassins côtiers de Guinée et de Guinée Bissau. Revue d'Hydrobiologie Tropicale, 22, 2: 107-127.
  • Paugy D., 1990b. Note à propos des Petersiini (Teleostei: Characidae) d’Afrique occidentale. Ichthyological Exploration of Freshwaters, 1: 75-84.
  • Paugy D., 2003. Alestidae: 236-282. In Paugy D., Lévêque C. & Teugels G.G. (eds). Faune des poissons d’eaux douces et saumâtres de l’Afrique de l’Ouest. IRD Éditions, Paris, MRAC, Tervuren, MNHN, Paris, collection Faune tropicale, 40, volume I, 800 p.
  • Paugy D. & Schaefer S.A., 2007. Alestidae: 347-411. In Stiassny M.L.J., Teugels G.G. & Hopkins C.D. (eds). The fresh and brackish water fishes of Lower Guinea, West-Central Africa, IRD Paris, MNHN Paris, MRAC Tervuren, Collection Faune et Flore tropicales, 42, volume 1, 800 p.
  • Poll M., 1967a. Révision des Characidae nains africains. Annales du Musée royal de l’Afrique centrale, série in-8°, Sciences Zoologiques, 162 p.
  • Svensson G.S.O., 1933. Freshwater fishes from the Gambia River. Kungliga Svenska Vetenskapsakademiens Handlingar, 12, 3: 102 p.
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    Rhabdalestes tangensis (Lönnberg, 1907)

    rhabdalestes_tangensis_picture

    Type and type locality

    Petersius tangensis Lönnberg, 1907: 2. Type locality: “Tanga”. Syntypes: NRMS 944.

     

    Synonyms

    Petersius tangensis Lönnberg, 1907

    Hemigrammopetersius tangensis Myers, 1929

    Micralestes (Rhabdalestes) tangensis tangensis Hoedeman, 1951

    Rhabdalestes tangensis Poll, 1967

    Hemigrammopetersius (Rhabdalestes) tangensis Géry, 1977

     

    Common names

    English: Pangani robber (Kenya)

    Estonian: Leleupi tintsalmler/Tanga tintsalmler

    Finnish: Tanganalesti

    German: Tangasalmler

    Swahili: Dagaa (Tanzania)

     

    Description

    Diagnosis: body depth 3.7 (3.75-4) and head length 4.1 (4-4.5) in SL. Dental formula: [5/8 (upper jaw), 8/0 (lower jaw)], [type: 4/8 (upper jaw), 8/0 (lower jaw)]. Cuspids number: [3/4-6 (upper jaw), 3-5/0 (lower jaw)]. Dorsal fin: II,8 (II,8) behind pelvic-fin insertion. Anal fin: III, 18 (III,16-17). Gill rakers: 14 (16-17). Scales: 35 + 2 (35-36) (longitudinal line); 6½ (above lateral line)/4½ (below lateral line) (6½/); 14 around caudal peduncle. Lateral line: 36 tubes.

    Maximum reported size: 80 mm SL.

    Colour: yellowish-silvery, a vague mid-lateral black band, more visible at the back.

     

    Distribution

    Pangani River basin and Lake Jipe (Tanzania) (see also Faunafri).

     

    IUCN assessment

    Relatively widespread with no major widespread threats identified.

    Major threats: no information available.

     

    FishBase link

     

    Bibliography

  • Copley H., 1958. Common freshwater fishes of East Africa. H.F. & G. Witherby Ltd , London, 172 p.
  • Eccles D.H., 1992. FAO species identification sheets for fishery purposes. Field guide to the freshwater fishes of Tanzania. Prepared and published with the support of the United Nations Development Programme (project URT/87/016), FAO, Rome, 145 p.
  • Lönnberg A.J.E., 1907. Fishes. In Zoologische Kilimandjaro-Meru Expedition 1905-1906 (by Y. Sjöstedt),. Stockholm, 5, 8 p.
  • Poll M., 1967a. Révision des Characidae nains africains. Annales du Musée royal de l’Afrique centrale, série in-8°, Sciences Zoologiques, 162 p.
  • Seegers L., De Vos L. & Okeyo D.O., 2003. Annotated checklist of the freshwater fishes of Kenya (excluding the lacustrine haplochromines from Lake Victoria). Journal of East African Natural History, 92: 11-47.
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    Rhabdalestes yokai Ibala Zamba & Vreven, 2008

    rhabdalestes_yokai_picture

    Type and type locality

    Rhabdalestes yokai Ibala Zamba & Vreven, 2008: 378-381, fig. 1-4. Type locality: Republic of Congo: Léfini River, acces canal to Lake Itsitso, left bank of Louna River, Lésio-Louna Natural Reserve, 3°03’S 15°49’E. Holotype: MRAC: 2004.046.P.0258; paratypes: AMNH 239654 (former MRAC 2004.046.P.0270-0272), MRAC 2004.046.P.0259-0269.

     

    Common names

    Estonian: Yoka tintsalmler

     

    Description

    Diagnosis: body depth 3.23-3.80 and head length 3.49-3,66 in SL. Dental formula: [5-7/8 (upper jaw), 8/0 (lower jaw)]. Cuspids number: [3-5/5-7 (upper jaw), 3-7/0 (lower jaw). Dorsal fin: II,8. Anal fin: III,17-19. Gill rakers: 13-14. Scales: 25-26 (longitudinal line); 4½ (above lateral line)/3½ (below lateral line); 10 around caudal peduncle. Lateral line complete with 25-26 tubes.

    Rhabdalestes yokai: morphometric and meristic data.

    morphological_characters_ryokai

    Maximum reported size: 52.2 mm SL.

    Colour: coloration of preserved specimens. Body pale brown, darker on dorsal midline and lighter, yellowish, ventrally. A dark brown band along lateral side of body, from posterior border of opercle to caudal-fin base. Snout and upper surface of head blackish. Head yellowish-white below eye. Opercule generally with numerous small, blackish, spots. Anal fin translucent, whitish, with a thin dark band at its base. In addition, another thin blackish band, broader anteriorly and gradually narrowing posteriorly, parallel to anal-fin base is present. Pectoral fins translucent, whitish, with numerous blackish points on upper fin rays giving a blackish appearance to upper part of these fins. Pelvic fin translucent, whitish. Dorsal and caudal fins with a light blackish hue due to a fine blackish pigmentation.

    Affinities: Rhabdalestes yokai can be distinguished from all other Rhabdalestes by the following combination of characters: 25-26 lateral line scales (vs 27-39 in R. aeratis, R. leleupi, R. maunensis, R. rhodesiensis and R. tangensis); a complete lateral line with 25-26 pored scales (vs incomplete with 6-7 pored scales in R. brevidorsalis); 5-7 outer premaxillary teeth with 5 cusps in the upper jaw, iii unbranched and 18-19 [exceptionally 17 (1 specimen)] branched anal-fin rays, and the lack of a black spot on the dorsal-fin tip [vs. 4 (exceptionally 6) outer premaxillary teeth with 3-5 cusps; iii unbranched and 13-17 branched anal-fin rays, and a black spot on the dorsal-fin tip in R. septentrionalis].

    Rhabdalestes yokai is morphologically closest to R. septentrionalis. Poll (1967) mentioned 4-6 outer premaxillary teeth for the species. According to Paugy (1990b), Paugy (2003) and Paugy & Schaefer (2007), R. septentrionalis has 4 outer premaxillary teeth with 3-5 cusps, iii unbranched and 13-17 branched anal-fin rays and a characteristic black spot at the tip of the dorsal fin. Our study confirms the observations of Paugy (1990b), Paugy (2003) and Paugy & Schaefer (2007) except for the outer premaxillary teeth of single specimen originating from Sierra Leone (MRAC 73-10-P-2105) with has 6 instead of the usual 4 outer premaxillary teeth.

     

    Distribution

    Rhabdalestes yokai is known from the type locality, the canal connecting Lake Itsotso with the Louna River, left bank of the Louna River, right bank affluent of the Léfini River, and sub-affluent of the right bank of the Congo River basin (Republic of Congo). In addition, a single sample confirms its presence in the Sangha River basin (Central African Republic). Based on these records, the species seems to be endemic to the Congo River basin (see also Faunafri).

     

    IUCN assessment

    Not evaluated

     

    FishBase link

     

    Bibliography

  • Ibala Zamba A. & Vreven E.J., 2008. Rhabdalestes yokai (Characiformes: Alestidae), a new species from the Léfini and Sangha River basins (Congo River basin), Africa. Ichthyological Exploration of Freshwaters, 19, 4:377-384.
  • Paugy D., 1990b. Note à propos des Petersiini (Teleostei: Characidae) d’Afrique occidentale. Ichthyological Exploration of Freshwaters, 1: 75-84.
  • Paugy D., 2003. Alestidae: 236-282. In Paugy D., Lévêque C. & Teugels G.G. (eds). Faune des poissons d’eaux douces et saumâtres de l’Afrique de l’Ouest. IRD Éditions, Paris, MRAC, Tervuren, MNHN, Paris, collection Faune tropicale, 40, volume I, 800 p.
  • Paugy D. & Schaefer S.A., 2007. Alestidae: 347-411. In Stiassny M.L.J., Teugels G.G. & Hopkins C.D. (eds). The fresh and brackish water fishes of Lower Guinea, West-Central Africa, IRD Paris, MNHN Paris, MRAC Tervuren, Collection Faune et Flore tropicales, 42, volume 1, 800 p.
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