Figure 13. Molecular phylogenetic analysis for Petrocephalus catostoma and three allopatric Petro... more Figure 13. Molecular phylogenetic analysis for Petrocephalus catostoma and three allopatric Petrocephalus species by Maximum Likelihood method. The evolutionary history was inferred by using the Maximum Likelihood method based on the Tamura–Nei model (Tamura and Nei 1993). The tree with the highest log likelihood (–1811.6564) is shown. The percentage of trees in which the associated taxa clustered together is shown next to the branches. Initial tree(s) for the heuristic search were obtained automatically as follows. When the number of common sites was <100 or less than one-quarter of the total number of sites, the maximum parsimony method was used; otherwise BIONJ method with the maximum composite likelihood distance matrix was used. The tree is drawn to scale, with branch lengths measured in the number of substitutions per site. The analysis involved 23 nucleotide sequences. Codon positions included were 1st+ 2nd+ 3rd+ Noncoding. There was a total of 477 positions in the final d...
Figure 7(A–E). Principal component analysis on the 13 anatomical characters of Table 3, for six O... more Figure 7(A–E). Principal component analysis on the 13 anatomical characters of Table 3, for six Okavango populations, focusing on the Guma Lagoon sample (Petrocephalus okavangensis sp. nov., red triangles). (A) Guma/Popa Falls (blue squares). (B) Guma/Gadikwe (blue squares). (C) Guma/Xakanixa Channel (blue squares). (D) Guma/Xakanixa River (blue squares). (E) Guma/Boro River (blue squares). (F) Popa Falls (red triangles)/Boro River (blue squares).
Figure 5. Principal component analysis for anatomy of Petrocephalus okavangensis sp. nov. (red tr... more Figure 5. Principal component analysis for anatomy of Petrocephalus okavangensis sp. nov. (red triangles) from (A, B) Guma Lagoon (n = 45) and (C, D) Popa Rapids (n = 36), compared with (A, C) P. longicapitis sp. nov. from Upper Zambezi River (blue squares) and (B, D) P. magnoculis sp. nov. (blue squares). Upper panels, analyses on 13 characters (see Table 3), lower panels, analyses on 17 characters (see Table 1, with HL/Na and LSc/HL excluded). Prin1–Prin3, for Principal Components 1–3.
Figure 4(A–H). Principal component analysis for 13 anatomical characters of Petrocephalus catosto... more Figure 4(A–H). Principal component analysis for 13 anatomical characters of Petrocephalus catostoma from Rovuma System (red triangles; n = 35) compared (one by one) with various allopatric Petrocephalus populations (blue squares): (A) with P. tanensis from Tana River (n = 52); (B) P. longicapitis sp. nov. from Upper Zambezi River (n = 38); (C) P. okavangensis sp. nov. from Guma Lagoon, Okavango (n = 45); (D) P. petersi sp. nov. from Lower Zambezi River (n = 11); (E) P. longianalis sp. nov. from Lufubu River (n = 49); (F) P. wesselsi from Incomati System (n = 44); (G) P. magnoculis sp. nov. from Cunene River (n = 9); (H) P. magnitrunci sp. nov. from Boro River (n = 11). (I) compares P. longicapitis sp. nov. from Upper Zambezi River (n = 38, red triangles) with P. magnoculis sp. nov. from the Cunene River (n = 9, blue squares). Prin1, Prin2, for Principal Components 1 and 2.
Figure 3. Schematic sketch of how measurements were taken on Petrocephalus sp. For abbreviations,... more Figure 3. Schematic sketch of how measurements were taken on Petrocephalus sp. For abbreviations, see Material and methods.
<i>Petrocephalus okavangensis</i> sp. nov. (Figure 2, no. 9; online Figure 10) A brie... more <i>Petrocephalus okavangensis</i> sp. nov. (Figure 2, no. 9; online Figure 10) A brief overview of records of Churchills from the Okavango is given in Skelton et al. (1985: 5), including a review of the discussions about their identity. Based on their own 'preliminary observations', these authors retained the name <i>P. catostoma</i>, 'pending further analysis of the problem'. <i>Type specimens.</i> Holotype: SAIAB 030046 (specimen R22) from Botswana, Okavango, Thoage River, Nguma (Guma) Lagoon. Paratypes: SAIAB 186062 (41 specimens). <i>Type locality.</i> Botswana, Okavango, Thoage River, Nguma (Guma) Lagoon, 18 ◦ 57 ′ 43.2 ′′ S, 22 ◦ 22 ′ 26.1 ′′ E. <i>Diagnosis.</i> Length of anal fin, LA, mean 0.264 (range 0.247 –0.286) of SL; number of anal fin rays, nA, median 30 (range 27–32); head length, HL, mean 0.25 (range 0.232 –0.274) of SL; depth of caudal peduncle, CPD, mean 0.311 (range 0.264 –0.349) of CPL, length of caudal peduncle; preanal length, PAL, mean 0.576 (range 0.538 –0.619) of SL; dorsal fin length, LD, mean 0.17 (range 0.145 –0.195) of SL; number of scales around caudal peduncle, SPc, median 12 (range 12–12); body depth, BD, mean 0.291 (range 0.261 –0.348) of SL; number of scales in lateral line row, SLS, median 37 (range 37–38). EOD characteristics at 25 ◦ C and "2% threshold criterion" (see Material and methods) for <i>n</i> = 2: peak amplitude of P2 phase, P2amp <i>&lt;</i> 0.13 of P1amp, peak amplitude of P1 phase; duration of P1 phase, P1dur, range 161–202 µs; duration of N phase, Ndur, range 65–83 µs; duration of P2 phase, P2dur, range 294–343 µs. <i>Description.</i> Body oval shape (Figure 2, no. 9). Head with distinctly pointed nose in most specimens, with a small ventrally positioned subterminal mouth, situated ventral to the eye; head and body dorsolaterally compressed. Dorsal fin (a) origin situated about two-thirds of standard length from snout, (b) obliquely orientated, anteriorly higher and posteriorly lower, (c) distal margin crescentic with anterior two or three rays longer than poste [...]
<i>Petrocephalus degeni</i> Boulenger, 1906 (resurrected species) (Figure 2, no. 27) ... more <i>Petrocephalus degeni</i> Boulenger, 1906 (resurrected species) (Figure 2, no. 27) <i>Petrocephalus degeni</i> Boulenger, 1906: 434; Whitehead and Greenwood 1959: 284 (synonymy with <i>Petrocephalus catostoma catostoma</i>). <i>Type specimens.</i> Holotype (unique): BMNH 1906.5.30.84 (studied). <i>Type locality.</i> Mouth of Katonga River, Lake Victoria (Uganda). <i>Diagnosis.</i> Preanal length, PAL 0.641 of SL; predorsal length, PDL 0.634 of SL; dorsal fin length, LD 0.155 of SL; anal fin length, LA 0.221 of SL; distance dorsal fin origin to end of caudal peduncle, pD 0.427 of SL; length of caudal peduncle, CPL 0.202 of SL; depth of caudal peduncle, CPD 0.369 of CPL; length of snout to centre of eye, LSc 0.258 of HL; length of snout to posterior orbital rim of eye, LSo 0.411 of HL; head length, HL 0.261 of SL; dorsal fin ray number, nD 19; anal fin ray number, nA 27; number of scales around caudal peduncle, SPc 12. <i>Etymology.</i> See title of Boulenger (1906): "... new Fishes discovered by Mr. E. Degen... ". <i>Remarks.</i> "Easily distinguished from its congeners in the short dorsal fin originating above the first ray of the anal" (Boulenger 1906: 434). Distinguished from all other species by highest PAL <i>/</i> SL and lowest LSc <i>/</i> HL, in combination with low LD <i>/</i> SL, low LA <i>/</i> SL, rather high pD <i>/</i> SL.
<i>Petrocephalus petersi</i> sp. nov. (Figure 2, no. 21) <i>Type specimens.<... more <i>Petrocephalus petersi</i> sp. nov. (Figure 2, no. 21) <i>Type specimens.</i> Holotype: SAIAB 060846 (specimen R1), Mozambique, stream near campsite 1, edge of wet Zambezi River System, Zambezi River. Paratypes: SAIAB 186055 (10 specimens). <i>Type locality.</i> Mozambique, stream near campsite 1, edge of wet Zambezi River System, Zambezi River, 18 ◦ 33 ′ 54 ′′ S, 35 ◦ 39 ′ 46 ′′ E. <i>Diagnosis.</i> Preanal length, PAL, mean 0.616 (range 0.595 –0.637) of SL; predorsal length, PDL, mean 0.642 (range 0.623 –0.658) of SL; length of snout to centre of eye, LSc, mean 0.364 (range 0.345 –0.383) of HL, head length; length of snout to posterior orbital rim of eye, LSo, mean 0.462 (range 0.442 –0.479) of HL, head length; body depth, BD, mean 0.299 (range 0.287 –0.323) of SL; number of scales around caudal peduncle, SPc, median 16 (range 12–16). <i>Description.</i> Body round-oval shape (Figure 2, no. 21). Head broadly rounded with a small ventrally positioned subterminal mouth, situated ventral to the eye; head and body dorsolaterally compressed. Dorsal fin (a) origin situated about two-thirds of standard length from snout, (b) obliquely orientated, anteriorly higher and posteriorly lower, (c) distal margin crescentic with anterior two or three rays longer than posterior rays, and (d) number of rays 18 (<i>n</i> = 2), 19 (<i>n</i> = 2), 20 (<i>n</i> = 7). Anal fin (a) longer than dorsal fin, (b) opposite dorsal fin with slightly more anterior origin, (c) obliquely orientated, anteriorly lower and posteriorly higher, (d) anterior 10 or so rays longer than posterior ones, especially in males where they also appear stronger, (e) margin broadly rounded, (f) rays posterior to first 10 with distal margin straight, (g) number of rays 25 (<i>n</i> = 4), 26 (<i>n</i> = 7). Forked tail fin with rounded lobes. Scales cycloid with reticulate striae, scales extending anteriorly to operculum and pectoral fins (beyond pelvics). Scales on caudal peduncle circumference, 12 (<i>n</i> = 1), 13 (<i>n</i> = 1), 14 (<i>n</i> = 2), 15 (<i>n< [...]
Extinction risk for 101 valid species and 18 unique genetic lineages of native freshwater fishes ... more Extinction risk for 101 valid species and 18 unique genetic lineages of native freshwater fishes of South Africa was assessed in 2016 following the IUCN Red List criteria. An additional five species (three new species that were described and two species that were revalidated subsequent to the 2016 assessments) were assessed in the present study. A synthesis of the outcome of the assessments of the 106 valid species and 18 genetic lineages indicates that 45 (36%) of South Africa's freshwater fish taxa are threatened (7 Critically Endangered, 25 Endangered, 13 Vulnerable). Of the remaining taxa, 17 (14%) are listed as Near Threatened, 57 (46%) are Least Concern and five (4%) are Data Deficient. More than 60% of the endemic taxa are threatened. The Cape Fold Ecoregion has the highest proportion of threatened taxa (67%) due to the existence of a unique assemblage of narrow‐range endemic species. Galaxias and Pseudobarbus have the highest number of highly threatened taxa as most of the species and lineages in these genera are classified as either CR or EN. Major threats to the native freshwater fishes of the country are invasive fish species, deterioration of water quality, impoundments and excessive water abstraction, land use changes and modification of riverine habitats. Immediate conservation efforts should focus on securing remnant populations of highly threatened taxa and preventing deterioration in threat status, because recovery is rare. Accurate delimitation of species boundaries, mapping their distribution ranges, improved knowledge of pressures and long‐term monitoring of population trends need to be prioritised to generate credible data for the 2026 IUCN threat status assessments and designation of important fish areas as part of the National Freshwater Ecosystem Priority Areas (NFEPA) initiative.
The present study describes Serranochromis alvum n. sp., Serranochromis swartzi n. sp., Serranoch... more The present study describes Serranochromis alvum n. sp., Serranochromis swartzi n. sp., Serranochromis cuanza n. sp., and Serranochromis cacuchi n. sp. from Angolan tributaries of the Cuanza and Okavango systems in Angola. The presence of four or five scale rows between the posterior margin of the orbit and the ascending arm of the preoperculum, the presence of widely set unicuspid teeth on the jaws, widely separated gill rakers, and anal fins with egg ocelli place these four species in Serranochromis. The Serranochromis described herein are distinguishable based on a combination of morphological and meristic characters, as well as pigmentation patterns. The interorbital width (14.3–15.9 % HL) of S. alvum is narrower than that of S. swartzi (17.6–19.8), S. cuanza (16.3–18.0), and S. cacuchi (20.0–21.7). Moreover, the interorbital width of S. cacuchi is greater than the other three described species. Serranochromis swartzi has a smaller preorbital depth (16.2–18.9 % HL) and snout length (29.6–31.9 % HL) than Serranochromis cuanza (PD 19.1–22.2, SNL 35.2–39.6 % HL). Serranochromis alvum is known only from the type locality at Cuito-Cuanavale at the junction of the Cuito and Cuanavale rivers, tributary to the Okavango River in Angola. Serranochromis swartzi is known only from the type locality in the Cuanza River, Angola. Serranochromis cuanza is restricted to the Cuanza River, below Capanda Dam, Angola, while S. cacuchi is known only from the Cacuchi River, a tributary of the Cuchi-Cubango River in Angola. The limited distribution of all four species and the absence of many congeners suggest, that in addition to previous studies that invoked a lacustrine speciation model, vicariance through drainage isolation seems to have played an important role in driving speciation in this group. The minimum polygon clusters that are formed when the first principal components of the meristic data are plotted against the second sheared principal components of the morphometric data show separation of the four new species.
The “Lacustricola” hutereaui species complex is herein defined by the possession of banded dorsal... more The “Lacustricola” hutereaui species complex is herein defined by the possession of banded dorsal, anal, and caudal fins in males and also by the pointed premaxilla ascending process, in which the premaxilla medial surface is slightly convex. “Lacustricola” pygmaeus, new species, known from the Okavango, Cuando, and upper Zambezi Rivers, is distinguished from the other species belonging to the “L.” hutereaui species complex by the following exclusive character states: an inconspicuous reticulate pattern on scale margins (vs. conspicuous); banded anal, dorsal, and caudal fin in females (vs. hyaline); faint bands in the middle rays of caudal fin in males (vs. conspicuous bands); rounded caudal fin in males (vs. slender); bright green-blue color in some of the flank scales (vs. absent); quadrate posterior margin with a deep concavity (vs. convex or about straight); and first dorsal-fin ray inserted in a vertical to second and third anal-fin ray (vs. fourth to eighth). Additionally, other morphometric, meristic, and osteological characters in combination proved to be useful in distinguishing the new species. Through the analysis of type material and recently collected specimens, the little known species “L.” chobensis is considered as a valid species and redescribed. It is easily distinguished from the other species belonging to the “L.” hutereaui species complex by a combination of external morphology, osteology, and coloration pattern characters. Comprehensive information on the osteology and external morphology of topotypes of “L.” hutereaui are presented, and description of coloration in life is provided for specimens from the Ubangui River, in the Central African Republic.
Figure 1. Map of southern Africa indicating the origin of samples of the Petrocephalus species st... more Figure 1. Map of southern Africa indicating the origin of samples of the Petrocephalus species studied. (1) Rovuma (Ruvuma) River, type locality for P. catostoma (Günther 1866) [BMNH 1863.10.12.4]; (2) Ruvu (Kingani) River, type locality for P. stuhlmanni Boulenger 1909 [BMNH 1907.12.3.1]; (3) Sabie River, type locality for P. wesselsi Kramer and Van der Bank 2000 [ZSM 28554 to ZSM 28566, SAIAB 054449]; (4) Groot Letaba River, Limpopo System [SAIAB 85920]; (5) Blyde River, Limpopo System [SAIAB 85923]; (6) Pongola River [SAIAB 85919] (7) Upper Zambezi River near Katima Mulilo, type locality for P. longicapitis sp. nov. [SAIAB 85916]; (8) Kwando River [ZSM 38658]; (9) Okavango Delta, Nguma Lagoon, type locality for P. okavangensis sp. nov. [SAIAB 030046]; (10) Tana River, type locality for P. catostoma tanensis Whitehead and Greenwood, 1959, here recognized as P. tanensis (Whitehead and Greenwood, 1959) [SAIAB 85907]; (11) Lake Rukwa [SAIAB 059515]; (12) Lufubu River, Luapula River s...
<i>Petrocephalus wesselsi</i> Kramer and Van der Bank, 2000 (Figure 2, no. 3; online ... more <i>Petrocephalus wesselsi</i> Kramer and Van der Bank, 2000 (Figure 2, no. 3; online Figure 14) <i>Type specimens.</i> Holotype: ZSM 28556 (one specimen) from Sabie River, Kruger National Park, South Africa. Paratypes: ZSM 28554 - ZSM 28565 (12 specimens); SMF 28266 (13 specimens), SAIAB (RUSI) 054449 (13 specimens). Studied. <i>Type locality.</i> Sabie River, Kruger National Park, bridge near Lower Sabie tourist camp, South Africa, 25 ◦ 07 ′ S, 31 ◦ 55 ′ E.
Figure 13. Molecular phylogenetic analysis for Petrocephalus catostoma and three allopatric Petro... more Figure 13. Molecular phylogenetic analysis for Petrocephalus catostoma and three allopatric Petrocephalus species by Maximum Likelihood method. The evolutionary history was inferred by using the Maximum Likelihood method based on the Tamura–Nei model (Tamura and Nei 1993). The tree with the highest log likelihood (–1811.6564) is shown. The percentage of trees in which the associated taxa clustered together is shown next to the branches. Initial tree(s) for the heuristic search were obtained automatically as follows. When the number of common sites was <100 or less than one-quarter of the total number of sites, the maximum parsimony method was used; otherwise BIONJ method with the maximum composite likelihood distance matrix was used. The tree is drawn to scale, with branch lengths measured in the number of substitutions per site. The analysis involved 23 nucleotide sequences. Codon positions included were 1st+ 2nd+ 3rd+ Noncoding. There was a total of 477 positions in the final d...
Figure 7(A–E). Principal component analysis on the 13 anatomical characters of Table 3, for six O... more Figure 7(A–E). Principal component analysis on the 13 anatomical characters of Table 3, for six Okavango populations, focusing on the Guma Lagoon sample (Petrocephalus okavangensis sp. nov., red triangles). (A) Guma/Popa Falls (blue squares). (B) Guma/Gadikwe (blue squares). (C) Guma/Xakanixa Channel (blue squares). (D) Guma/Xakanixa River (blue squares). (E) Guma/Boro River (blue squares). (F) Popa Falls (red triangles)/Boro River (blue squares).
Figure 5. Principal component analysis for anatomy of Petrocephalus okavangensis sp. nov. (red tr... more Figure 5. Principal component analysis for anatomy of Petrocephalus okavangensis sp. nov. (red triangles) from (A, B) Guma Lagoon (n = 45) and (C, D) Popa Rapids (n = 36), compared with (A, C) P. longicapitis sp. nov. from Upper Zambezi River (blue squares) and (B, D) P. magnoculis sp. nov. (blue squares). Upper panels, analyses on 13 characters (see Table 3), lower panels, analyses on 17 characters (see Table 1, with HL/Na and LSc/HL excluded). Prin1–Prin3, for Principal Components 1–3.
Figure 4(A–H). Principal component analysis for 13 anatomical characters of Petrocephalus catosto... more Figure 4(A–H). Principal component analysis for 13 anatomical characters of Petrocephalus catostoma from Rovuma System (red triangles; n = 35) compared (one by one) with various allopatric Petrocephalus populations (blue squares): (A) with P. tanensis from Tana River (n = 52); (B) P. longicapitis sp. nov. from Upper Zambezi River (n = 38); (C) P. okavangensis sp. nov. from Guma Lagoon, Okavango (n = 45); (D) P. petersi sp. nov. from Lower Zambezi River (n = 11); (E) P. longianalis sp. nov. from Lufubu River (n = 49); (F) P. wesselsi from Incomati System (n = 44); (G) P. magnoculis sp. nov. from Cunene River (n = 9); (H) P. magnitrunci sp. nov. from Boro River (n = 11). (I) compares P. longicapitis sp. nov. from Upper Zambezi River (n = 38, red triangles) with P. magnoculis sp. nov. from the Cunene River (n = 9, blue squares). Prin1, Prin2, for Principal Components 1 and 2.
Figure 3. Schematic sketch of how measurements were taken on Petrocephalus sp. For abbreviations,... more Figure 3. Schematic sketch of how measurements were taken on Petrocephalus sp. For abbreviations, see Material and methods.
<i>Petrocephalus okavangensis</i> sp. nov. (Figure 2, no. 9; online Figure 10) A brie... more <i>Petrocephalus okavangensis</i> sp. nov. (Figure 2, no. 9; online Figure 10) A brief overview of records of Churchills from the Okavango is given in Skelton et al. (1985: 5), including a review of the discussions about their identity. Based on their own 'preliminary observations', these authors retained the name <i>P. catostoma</i>, 'pending further analysis of the problem'. <i>Type specimens.</i> Holotype: SAIAB 030046 (specimen R22) from Botswana, Okavango, Thoage River, Nguma (Guma) Lagoon. Paratypes: SAIAB 186062 (41 specimens). <i>Type locality.</i> Botswana, Okavango, Thoage River, Nguma (Guma) Lagoon, 18 ◦ 57 ′ 43.2 ′′ S, 22 ◦ 22 ′ 26.1 ′′ E. <i>Diagnosis.</i> Length of anal fin, LA, mean 0.264 (range 0.247 –0.286) of SL; number of anal fin rays, nA, median 30 (range 27–32); head length, HL, mean 0.25 (range 0.232 –0.274) of SL; depth of caudal peduncle, CPD, mean 0.311 (range 0.264 –0.349) of CPL, length of caudal peduncle; preanal length, PAL, mean 0.576 (range 0.538 –0.619) of SL; dorsal fin length, LD, mean 0.17 (range 0.145 –0.195) of SL; number of scales around caudal peduncle, SPc, median 12 (range 12–12); body depth, BD, mean 0.291 (range 0.261 –0.348) of SL; number of scales in lateral line row, SLS, median 37 (range 37–38). EOD characteristics at 25 ◦ C and "2% threshold criterion" (see Material and methods) for <i>n</i> = 2: peak amplitude of P2 phase, P2amp <i>&lt;</i> 0.13 of P1amp, peak amplitude of P1 phase; duration of P1 phase, P1dur, range 161–202 µs; duration of N phase, Ndur, range 65–83 µs; duration of P2 phase, P2dur, range 294–343 µs. <i>Description.</i> Body oval shape (Figure 2, no. 9). Head with distinctly pointed nose in most specimens, with a small ventrally positioned subterminal mouth, situated ventral to the eye; head and body dorsolaterally compressed. Dorsal fin (a) origin situated about two-thirds of standard length from snout, (b) obliquely orientated, anteriorly higher and posteriorly lower, (c) distal margin crescentic with anterior two or three rays longer than poste [...]
<i>Petrocephalus degeni</i> Boulenger, 1906 (resurrected species) (Figure 2, no. 27) ... more <i>Petrocephalus degeni</i> Boulenger, 1906 (resurrected species) (Figure 2, no. 27) <i>Petrocephalus degeni</i> Boulenger, 1906: 434; Whitehead and Greenwood 1959: 284 (synonymy with <i>Petrocephalus catostoma catostoma</i>). <i>Type specimens.</i> Holotype (unique): BMNH 1906.5.30.84 (studied). <i>Type locality.</i> Mouth of Katonga River, Lake Victoria (Uganda). <i>Diagnosis.</i> Preanal length, PAL 0.641 of SL; predorsal length, PDL 0.634 of SL; dorsal fin length, LD 0.155 of SL; anal fin length, LA 0.221 of SL; distance dorsal fin origin to end of caudal peduncle, pD 0.427 of SL; length of caudal peduncle, CPL 0.202 of SL; depth of caudal peduncle, CPD 0.369 of CPL; length of snout to centre of eye, LSc 0.258 of HL; length of snout to posterior orbital rim of eye, LSo 0.411 of HL; head length, HL 0.261 of SL; dorsal fin ray number, nD 19; anal fin ray number, nA 27; number of scales around caudal peduncle, SPc 12. <i>Etymology.</i> See title of Boulenger (1906): "... new Fishes discovered by Mr. E. Degen... ". <i>Remarks.</i> "Easily distinguished from its congeners in the short dorsal fin originating above the first ray of the anal" (Boulenger 1906: 434). Distinguished from all other species by highest PAL <i>/</i> SL and lowest LSc <i>/</i> HL, in combination with low LD <i>/</i> SL, low LA <i>/</i> SL, rather high pD <i>/</i> SL.
<i>Petrocephalus petersi</i> sp. nov. (Figure 2, no. 21) <i>Type specimens.<... more <i>Petrocephalus petersi</i> sp. nov. (Figure 2, no. 21) <i>Type specimens.</i> Holotype: SAIAB 060846 (specimen R1), Mozambique, stream near campsite 1, edge of wet Zambezi River System, Zambezi River. Paratypes: SAIAB 186055 (10 specimens). <i>Type locality.</i> Mozambique, stream near campsite 1, edge of wet Zambezi River System, Zambezi River, 18 ◦ 33 ′ 54 ′′ S, 35 ◦ 39 ′ 46 ′′ E. <i>Diagnosis.</i> Preanal length, PAL, mean 0.616 (range 0.595 –0.637) of SL; predorsal length, PDL, mean 0.642 (range 0.623 –0.658) of SL; length of snout to centre of eye, LSc, mean 0.364 (range 0.345 –0.383) of HL, head length; length of snout to posterior orbital rim of eye, LSo, mean 0.462 (range 0.442 –0.479) of HL, head length; body depth, BD, mean 0.299 (range 0.287 –0.323) of SL; number of scales around caudal peduncle, SPc, median 16 (range 12–16). <i>Description.</i> Body round-oval shape (Figure 2, no. 21). Head broadly rounded with a small ventrally positioned subterminal mouth, situated ventral to the eye; head and body dorsolaterally compressed. Dorsal fin (a) origin situated about two-thirds of standard length from snout, (b) obliquely orientated, anteriorly higher and posteriorly lower, (c) distal margin crescentic with anterior two or three rays longer than posterior rays, and (d) number of rays 18 (<i>n</i> = 2), 19 (<i>n</i> = 2), 20 (<i>n</i> = 7). Anal fin (a) longer than dorsal fin, (b) opposite dorsal fin with slightly more anterior origin, (c) obliquely orientated, anteriorly lower and posteriorly higher, (d) anterior 10 or so rays longer than posterior ones, especially in males where they also appear stronger, (e) margin broadly rounded, (f) rays posterior to first 10 with distal margin straight, (g) number of rays 25 (<i>n</i> = 4), 26 (<i>n</i> = 7). Forked tail fin with rounded lobes. Scales cycloid with reticulate striae, scales extending anteriorly to operculum and pectoral fins (beyond pelvics). Scales on caudal peduncle circumference, 12 (<i>n</i> = 1), 13 (<i>n</i> = 1), 14 (<i>n</i> = 2), 15 (<i>n< [...]
Extinction risk for 101 valid species and 18 unique genetic lineages of native freshwater fishes ... more Extinction risk for 101 valid species and 18 unique genetic lineages of native freshwater fishes of South Africa was assessed in 2016 following the IUCN Red List criteria. An additional five species (three new species that were described and two species that were revalidated subsequent to the 2016 assessments) were assessed in the present study. A synthesis of the outcome of the assessments of the 106 valid species and 18 genetic lineages indicates that 45 (36%) of South Africa's freshwater fish taxa are threatened (7 Critically Endangered, 25 Endangered, 13 Vulnerable). Of the remaining taxa, 17 (14%) are listed as Near Threatened, 57 (46%) are Least Concern and five (4%) are Data Deficient. More than 60% of the endemic taxa are threatened. The Cape Fold Ecoregion has the highest proportion of threatened taxa (67%) due to the existence of a unique assemblage of narrow‐range endemic species. Galaxias and Pseudobarbus have the highest number of highly threatened taxa as most of the species and lineages in these genera are classified as either CR or EN. Major threats to the native freshwater fishes of the country are invasive fish species, deterioration of water quality, impoundments and excessive water abstraction, land use changes and modification of riverine habitats. Immediate conservation efforts should focus on securing remnant populations of highly threatened taxa and preventing deterioration in threat status, because recovery is rare. Accurate delimitation of species boundaries, mapping their distribution ranges, improved knowledge of pressures and long‐term monitoring of population trends need to be prioritised to generate credible data for the 2026 IUCN threat status assessments and designation of important fish areas as part of the National Freshwater Ecosystem Priority Areas (NFEPA) initiative.
The present study describes Serranochromis alvum n. sp., Serranochromis swartzi n. sp., Serranoch... more The present study describes Serranochromis alvum n. sp., Serranochromis swartzi n. sp., Serranochromis cuanza n. sp., and Serranochromis cacuchi n. sp. from Angolan tributaries of the Cuanza and Okavango systems in Angola. The presence of four or five scale rows between the posterior margin of the orbit and the ascending arm of the preoperculum, the presence of widely set unicuspid teeth on the jaws, widely separated gill rakers, and anal fins with egg ocelli place these four species in Serranochromis. The Serranochromis described herein are distinguishable based on a combination of morphological and meristic characters, as well as pigmentation patterns. The interorbital width (14.3–15.9 % HL) of S. alvum is narrower than that of S. swartzi (17.6–19.8), S. cuanza (16.3–18.0), and S. cacuchi (20.0–21.7). Moreover, the interorbital width of S. cacuchi is greater than the other three described species. Serranochromis swartzi has a smaller preorbital depth (16.2–18.9 % HL) and snout length (29.6–31.9 % HL) than Serranochromis cuanza (PD 19.1–22.2, SNL 35.2–39.6 % HL). Serranochromis alvum is known only from the type locality at Cuito-Cuanavale at the junction of the Cuito and Cuanavale rivers, tributary to the Okavango River in Angola. Serranochromis swartzi is known only from the type locality in the Cuanza River, Angola. Serranochromis cuanza is restricted to the Cuanza River, below Capanda Dam, Angola, while S. cacuchi is known only from the Cacuchi River, a tributary of the Cuchi-Cubango River in Angola. The limited distribution of all four species and the absence of many congeners suggest, that in addition to previous studies that invoked a lacustrine speciation model, vicariance through drainage isolation seems to have played an important role in driving speciation in this group. The minimum polygon clusters that are formed when the first principal components of the meristic data are plotted against the second sheared principal components of the morphometric data show separation of the four new species.
The “Lacustricola” hutereaui species complex is herein defined by the possession of banded dorsal... more The “Lacustricola” hutereaui species complex is herein defined by the possession of banded dorsal, anal, and caudal fins in males and also by the pointed premaxilla ascending process, in which the premaxilla medial surface is slightly convex. “Lacustricola” pygmaeus, new species, known from the Okavango, Cuando, and upper Zambezi Rivers, is distinguished from the other species belonging to the “L.” hutereaui species complex by the following exclusive character states: an inconspicuous reticulate pattern on scale margins (vs. conspicuous); banded anal, dorsal, and caudal fin in females (vs. hyaline); faint bands in the middle rays of caudal fin in males (vs. conspicuous bands); rounded caudal fin in males (vs. slender); bright green-blue color in some of the flank scales (vs. absent); quadrate posterior margin with a deep concavity (vs. convex or about straight); and first dorsal-fin ray inserted in a vertical to second and third anal-fin ray (vs. fourth to eighth). Additionally, other morphometric, meristic, and osteological characters in combination proved to be useful in distinguishing the new species. Through the analysis of type material and recently collected specimens, the little known species “L.” chobensis is considered as a valid species and redescribed. It is easily distinguished from the other species belonging to the “L.” hutereaui species complex by a combination of external morphology, osteology, and coloration pattern characters. Comprehensive information on the osteology and external morphology of topotypes of “L.” hutereaui are presented, and description of coloration in life is provided for specimens from the Ubangui River, in the Central African Republic.
Figure 1. Map of southern Africa indicating the origin of samples of the Petrocephalus species st... more Figure 1. Map of southern Africa indicating the origin of samples of the Petrocephalus species studied. (1) Rovuma (Ruvuma) River, type locality for P. catostoma (Günther 1866) [BMNH 1863.10.12.4]; (2) Ruvu (Kingani) River, type locality for P. stuhlmanni Boulenger 1909 [BMNH 1907.12.3.1]; (3) Sabie River, type locality for P. wesselsi Kramer and Van der Bank 2000 [ZSM 28554 to ZSM 28566, SAIAB 054449]; (4) Groot Letaba River, Limpopo System [SAIAB 85920]; (5) Blyde River, Limpopo System [SAIAB 85923]; (6) Pongola River [SAIAB 85919] (7) Upper Zambezi River near Katima Mulilo, type locality for P. longicapitis sp. nov. [SAIAB 85916]; (8) Kwando River [ZSM 38658]; (9) Okavango Delta, Nguma Lagoon, type locality for P. okavangensis sp. nov. [SAIAB 030046]; (10) Tana River, type locality for P. catostoma tanensis Whitehead and Greenwood, 1959, here recognized as P. tanensis (Whitehead and Greenwood, 1959) [SAIAB 85907]; (11) Lake Rukwa [SAIAB 059515]; (12) Lufubu River, Luapula River s...
<i>Petrocephalus wesselsi</i> Kramer and Van der Bank, 2000 (Figure 2, no. 3; online ... more <i>Petrocephalus wesselsi</i> Kramer and Van der Bank, 2000 (Figure 2, no. 3; online Figure 14) <i>Type specimens.</i> Holotype: ZSM 28556 (one specimen) from Sabie River, Kruger National Park, South Africa. Paratypes: ZSM 28554 - ZSM 28565 (12 specimens); SMF 28266 (13 specimens), SAIAB (RUSI) 054449 (13 specimens). Studied. <i>Type locality.</i> Sabie River, Kruger National Park, bridge near Lower Sabie tourist camp, South Africa, 25 ◦ 07 ′ S, 31 ◦ 55 ′ E.
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