Research Article |
Corresponding author: Albert Chakona ( a.chakona@saiab.ac.za ) Academic editor: Maria Elina Bichuette
© 2017 Albert Chakona, Paul H. Skelton.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Chakona A, Skelton PH (2017) A review of the Pseudobarbus afer (Peters, 1864) species complex (Teleostei, Cyprinidae) in the eastern Cape Fold Ecoregion of South Africa. ZooKeys 657: 109-140. https://doi.org/10.3897/zookeys.657.11076
|
The Eastern Cape redfin, Pseudobarbus afer, has long been considered to be a single widespread and variable species occurring in multiple isolated river systems in the Cape Fold Ecoregion (CFE) at the southern tip of Africa. Mitochondrial cytochrome b and control region sequence data of individuals from populations currently assigned to P. afer across the species’ distribution range revealed existence of four deeply divergent taxonomic units: (i) the Mandela lineage confined to the Sundays, Swartkops and Baakens river systems, (ii) the Krom lineage endemic to the Krom River system, (iii) the St Francis lineage occurring in the Gamtoos and adjacent river systems, and (iv) the Forest lineage occurring in several coastal river systems from the Tsitsikamma to the Klein Brak River system. The Forest lineage is closely related to P. phlegethon from the Olifants River system on the west coast of South Africa, suggesting that it does not belong to P. afer s.l. Herein we focus on the three lineages within the P. afer s.l. complex and provide new diagnosis for P. afer s.s (Mandela lineage), revalidate P. senticeps (Krom lineage) as a distinct species, and describe a new species P. swartzi (St Francis lineage). The three species exhibit subtle differences, which explains why they were previously considered to represent a single variable and widespread species. Pseudobarbus senticeps differs from both P. afer and P. swartzi by having fewer (i.e. larger) scales (25–33, mode 29 lateral line scale series; 10–12, mode 11 circumpeduncular scales) and presence of a lateral stripe which terminates in a conspicuous triangular blotch at the base of the caudal fin. Long barbels which reach or surpass the vertical through the posterior edge of the eye further separate P. senticeps from P. afer s.s. which possesses simple short barbels which do not reach the vertical through the posterior margin of the eye. Pseudobarbus afer s.s differs from P. swartzi sp. n. by possession of fewer scale rows along the lateral line (29–35, mode 32 vs 34–37, mode 36 in P. swartzi), fewer scales around the caudal peduncle (12–16, mode 12 vs 13–17, mode 16 in P. swartzi) and a distinct mesh or net-like pigmentation pattern on latero-ventral scales.
Cape Fold Ecoregion, endemic hotspot, single barbeled redfins, Pseudobarbus senticeps , P. swartzi
The cyprinid genus Pseudobarbus currently contains nine valid species endemic to southern Africa. All species of this genus are confined to streams associated with the Cape Fold Ecoregion (CFE) at the southern tip of Africa, with the exception of P. quathlambae which is endemic to the headwater tributaries of the Orange River in the Lesotho Highlands (
Many species of Pseudobarbus have restricted distribution ranges (
The taxonomic integrity of the Eastern Cape redfin, P. afer, however remained unclear as
A molecular study by
Herein we demonstrate that, in addition to their deep genetic divergence, the Krom, St Francis and Mandela lineages can be separated based on scale counts, length of oral barbels and consistent differences in body colour pattern, supporting their status as distinct species. As the specimens that were used for
Morphometric and meristic data used for the present study were generated from both historical collections obtained from the South African Institute for Aquatic Biodiversity (
Fresh topotypic specimens for P. afer s.s. were collected from the Blindekloof River, a tributary of the Swartkops River system between 2010 and 2015. Topotypic specimens for P. senticeps were collected from the Assegaaibos River, a tributary of the Krom River system in 2014. Additional DNA tissue samples were taken from specimens collected from 10 localities in 2015 and 2016 to fill in sampling gaps in the Kouga and Groot sub-catchments of the Gamtoos River system. Methods for obtaining DNA sequence data and their analyses follow
Methods used to obtain meristic and morphometric data (Table
Morphological characters of Pseudobarbus species used in the present study (reproduced from
Character | Description | Acronym |
---|---|---|
Morphometric measurements | ||
Standard length | Tip of the snout to the point of flexure of the caudal fin | SL |
Pre-dorsal length | Tip of the snout to the origin of the dorsal fin | PDL |
Head length | Tip of the snout to the posterior bony margin of the operculum | HL |
Snout length | Tip of the snout to the anterior bony edge of the orbit | S |
Orbit diameter | The greatest bony diameter of the orbit | OD |
Inter-orbit length | Straight line distance between the bony edges of the orbits | IO |
Post-orbit length | Distance between the posterior bony edge of orbit to the posterior bony edge of operculum | PO |
Head depth | Maximum depth measured from the nape | HD |
Body depth | Maximum depth measured from the anterior base of the dorsal fin | BD |
Anterior barbel length | From base to tip of anterior barbel | AB |
Posterior barbel length | From base to tip of posterior barbel | PB |
Dorsal fin base | Distance between anterior and posterior base of dorsal fin | DB |
Dorsal fin height | From anterior base to tip of dorsal fin | DH |
Pectoral fin length | From anterior base to tip of pectoral fin | PtL |
Pelvic fin length | From anterior base to tip of pelvic fin | PvL |
Anal fin base | Distance between anterior and posterior base of anal fin | AfB |
Anal fin height | From anterior base to tip of anal fin | AfH |
Caudal peduncle length | Distance from posterior base of anal fin the point of flexure of the caudal fin | CPL |
Caudal peduncle depth | The least depth of the caudal peduncle | CPD |
Pectoral to pelvic fin length | Distance between the posterior margins of the fin bases | PP |
Pelvic to anal fin length | Distance between the posterior base of the pelvic fin to the anterior base of the anal fin | PA |
Body width | The greatest width just anterior to the origin of the dorsal fin | BW |
Meristic counts | ||
Lateral line scales | Number of scale rows along the lateral line | LL |
Lateral line to dorsal fin scales | Number of scale rows between lateral line scale row and anterior base of the dorsal fin | LD |
Lateral line to pelvic fin scales | Number of scale rows between lateral line scale row and base of pelvic fin | LP |
Lateral line to anal fin scales | Number of scale rows between lateral line scale row and anterior base of the anal fin | LA |
Caudal peduncle scales | Number of scale rows around the caudal peduncle | CP |
Predorsal scales | Number of scale rows from the edge of the nape to the anterior base of the dorsal fin | PDS |
Unbranched dorsal fin rays | Number of unbranched primary dorsal rays | UdR |
Branched dorsal fin rays | Number of branched dorsal rays | BdR |
Total vertebrae | Total number of vertebrae in vertebral column (including four Weberian vertebrae and a single ural centrum) | TV |
Pre-dorsal vertebrae | Total number of vertebrae in advance of the leading dorsal fin pterygiophore (including the four Weberian vertebrae) | PdV |
Pre-caudal vertebrae | Total number of vertebrae in advance of the first caudal vertebrae (i.e. the vertebrae opposite the leading anal pterygiophore) plus the four Weberian vertebrae | PcV |
Pre-anal vertebrae | Total number of vertebrae in advance of the leading anal pterygiophore (including the four Weberian vertebrae) | PaV |
Caudal vertebrae | Total number of vertebrae before the last precaudal vertebrae (including a single ural centrum) | CV |
We included additional raw data from
Principal Component Analysis (PCA) was performed on raw meristic variables and morphometric variables in percentages as well as log transformed morphometric data to explore the separation of the specimens and identify the variables that contribute the most to differences among groups. Fin and barbel erosion was observed in some specimens, particularly those that were collected from polluted waters. Such specimens were excluded from the PCA for morphometric data. Morphometric and meristic data were analysed separately using the statistical program PAST (
Consistent with results from previous studies, Bayesian phylogenetic analysis recovered four major clades within P. afer (Figure
Bayesian phylogenetic tree showing genetic distances between Pseudobarbus afer s. s, P. senticeps and P. swartzi sp. n. and their relationships with the other single barbeled Pseudobarbus species and lineages in the Cape Fold Ecoregion of South Africa. Bayesian posterior probabilities are shown on the branches. The symbols correspond to the distribution map of the three species in Figure
Ranges of model-corrected genetic divergences (%) between species and lineages (in parenthesis) of the soft-rayed redfins of the genus Pseudobarbus.
afer s.s | swartzi | senticeps | asper | tenuis | phlegethon | afer (forest) | quathlambae | skeltoni | burchelli (breede) | burchelli (heuningnes) | burchelli (tradou) | burgi | verloreni | |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
afer s.s | 0.00–1.03 | |||||||||||||
swartzi | 4.76–6.61 | 0.00–0.40 | ||||||||||||
senticeps | 6.75–7.81 | 3.32–4.09 | 0.00–0.20 | |||||||||||
asper | 8.59–10.12 | 8.25–8.89 | 9.87–10.23 | – | ||||||||||
tenuis | 5.94–8.97 | 5.86–7.37 | 6.69–9.23 | 3.04–4.25 | 0.00–1.88 | |||||||||
phlegethon | 5.27–5.84 | 4.34–4.89 | 6.24–6.54 | 9.17 | 7.90–9.56 | – | ||||||||
afer (forest) | 7.65–8.30 | 5.66–6.23 | 7.91–7.58 | 10.75 | 8.76–10.52 | 5.72 | – | |||||||
quathlambae | 19.43–22.06 | 19.28–21.54 | 20.20–22.48 | 21.23–22.91 | 18.71–20.48 | 20.80–21.59 | 19.75–21.59 | 0.00–2.34 | ||||||
skeltoni | 12.84–15.03 | 10.39–11.19 | 13.00–13.02 | 17.22–17.72 | 14.96–17.38 | 13.73–14.16 | 10.98–11.38 | 25.22 –27.79 | 0.00–0.20 | |||||
burchelli (breede) | 6.80–8.48 | 6.00–6.89 | 8.08–8.72 | 9.77–10.10 | 7.86–9.82 | 8.10–8.40 | 8.36–8.68 | 16.79–17.47 | 9.92–10.65 | 0.00–0.19 | ||||
burchelli (heuningnes) | 6.51–7.87 | 5.19–5.76 | 7.80–8.12 | 10.86 | 8.23–9.91 | 7.81 | 8.11 | 19.10–19.85 | 9.98–10.35 | 1.89–2.10 | – | |||
burchelli (tradou) | 6.90–8.29 | 6.70–7.03 | 8.30–8.64 | 10.47 | 8.07–9.65 | 9.61 | 8.28 | 16.05–16.66 | 9.49–9.87 | 4.10–4.35 | 4.39 | – | ||
burgi | 8.95–10.03 | 7.63–7.98 | 9.31–9.67 | 9.74 | 9.86–11.55 | 8.67 | 9.92 | 22.73–23.52 | 13.01–13.43 | 7.19–7.49 | 6.32 | 7.97 | – | |
verloreni | 9.84–11.44 | 8.95–9.62 | 9.22–9.91 | 11.85–12.54 | 8.71–10.97 | 12.47–12.83 | 10.26–0.97 | 19.66–23.78 | 12.40–12.83 | 6.92–8.12 | 7.27–8.19 | 6.44–7.33 | 9.50–10.19 | 0.00–0.60 |
The first PCA performed on five meristics for 162 specimens of P. afer s.l. shows clear separation of P. afer s.s., P. senticeps and P. swartzi sp. n. based on scale counts (Figure
a Scatter plot of PC1 against PC2 for a PCA carried out on five raw meristic characters (scale counts) for 162 specimens of the Pseudobarbus afer complex b Scatter plot of PC1 against PC2 for a PCA carried out on 17 morphometric characters for 154 specimens of the Pseudobarbus afer complex. Syntypes were not included in the analyses as all three specimens are in very poor condition, with very few intact scales, flaccid bodies and damaged fins. The plots indicate that P. senticeps, P. afer s.s. and P. swartzi can be clearly separated based on scale counts, but the three species show considerable overlap in morphological characters.
Factor loadings for the first two principal component (PC) axes of a PCA carried out on five meristic characters from 162 specimens of the Pseudobarbus afer complex. The most important factor loadings are in bold.
PCI | PCII | PCIII | |
---|---|---|---|
Eigenvalue | 12.105 | 1.251 | 0.284 |
% Variance | 87.20 | 9.01 | 2.05 |
Lateral line scale series | 0.857 | -0.494 | 0.131 |
Lateral line to dorsal fin scale rows | 0.143 | 0.143 | -0.727 |
Lateral line to pelvic fin scale rows | 0.134 | 0.034 | -0.491 |
Lateral line to anal fin scale rows | 0.150 | 0.080 | -0.386 |
Circumpeduncular scale rows | 0.453 | 0.853 | 0.254 |
Morphometric and meristic data for Pseudobarbus afer s.s, P. senticeps and P. swartzi sp. n.
P. afer | P. senticeps | P. swartzi sp. n. | ||||
---|---|---|---|---|---|---|
syntypes‡ n = 3 |
other specimens including topotypes n = 68 |
holotype | topotypes n = 29 |
holotype | other specimens including paratypes n = 63 |
|
Standard length (SL) (mm) | 79.1–89.0 | 43.0–82.0 | 67.0 | 45.0–79.3 | 81.1 | 46.5–75.2 |
Head length (HL) (mm) | 22.4–26.7 | 11.7–22.5 | 18.2 | 12.8–21.1 | 22.3 | 12.8–21.2 |
Percentage of SL (%) | ||||||
Head length | 24.1–30.0 | 25.4–28.9 | 27.2 | 26.1–29.6 | 27.5 | 26.6–30.0 |
Predorsal length | 51.2–55.0 | 49.6–55.5 | 50.7 | 49.3–55.0 | 53.8 | 53.3–56.6 |
Dorsal fin base | 11.4–12.4 | 11.0–14.4 | 14.9 | 11.0–14.9 | 12.7 | 10.8–13.4 |
Dorsal fin height | – | 20.4–25.2 | 25.4 | 20.8–25.4 | 24.9 | 23.5–27.8 |
Body depth | 24.3–27.9 | 22.5–31.6 | 28.7 | 22.9–28.7 | 26.1 | 22.6–25.9 |
Body width | 10.8–13.2 | 11.9–20.2 | 13.9 | 13.9–19.3 | 17.8 | 14.6–17.7 |
Caudal peduncle length | 23.4–24.9 | 23.0–27.6 | 26.0 | 22.5–26.2 | 23.4 | 22.2–25.4 |
Percentage of HL (%) | ||||||
Head depth | 61.8–70.7 | 66.5–78.2 | 73.6 | 65.3–74.3 | 72.6 | 63.7–71.6 |
Inter-obit | 27.7–34.8 | 25.2–33.0 | 30.8 | 27.1–33.0 | 34.5 | 25.7–31.2 |
Snout length | 24.0–29.3 | 29.7–39.0 | 34.6 | 29.8–37.9 | 33.6 | 28.9–34.0 |
Post orbit | 40.8–49.7 | 42.2–51.2 | 52.7 | 44.2–52.7 | 50.7 | 44.6–47.7 |
Posterior barbel length | 16.4–23.6 | 12.1–27.2 | 33.0 | 26.0–37.0 | 27.8 | 26.7–39.9 |
Orbit diameter | 21.7–29.5 | 21.7–30.4 | 25.8 | 23.5–29.5 | 25.6 | 23.0–27.7 |
Percentage of caudal peduncle length (%) | ||||||
Caudal peduncle depth | 43.2–50.9 | 40.3–61.5 | 52.3 | 43.0–54.5 | 57.9 | 43.6–54.3 |
Unbranched dorsal fin rays | ii–iii | iv (iii–iv) | iii | iv (iii–iv) | iii | iii |
Branched dorsal fin rays | 7 | 7 (6–7) | 7 | 7 | 7 | 7 |
Unbranched anal fin rays | iii | iii | iii | iii | iii | iii |
Branched anal fin rays | 5 | 5 | 5 | 5 | 5 | 5 |
Pectoral fin rays | 13–14 | 15 (14–17) | 14 | 14 (13–15) | 13 | 14 (12–14) |
Pelvic fin rays | 8 | 8 (8–9) | 8 | 8 (8–9) | 7 | 8 (7–8) |
Lateral line scales | 29–33 | 32 (29–35) | 29 | 29 (25–30) | 36 | 36 (35–37) |
Lateral line to dorsal fin scale rows | 4 | 5 (4–6) | 5 | 5 (4–5) | 6 | 6 (6–7) |
Lateral line to pelvic fin scale rows | – | 4 (3–5) | 4 | 4 (3–4) | 5 | 5 (4–5) |
Lateral line to anal fin scale rows | – | 4 (3–5) | 4 | 3 (3–4) | 5 | 5 |
Caudal peduncle scale rows | 12–14 | 12 (12–16) | 12 | 12 (10–12) | 16 | 16 (15–16) |
Predorsal scale rows | 13–15 | 15 (14–16) | 14 | 15 (12–15) | 16 | 17–18 (16–20) |
Total vertebrae | 37 (36–39) | 37 (35–38) | 37 | 37 (37–38)* | ||
Precaudal vertebrae | 19 (18–20) | 19 (18–19) | 19 | 20 (19–20)* | ||
Caudal vertebrae | 18 (17–19) | 18 (16–18) | 18 | 18 (17–18)* | ||
Predorsal vertebrae | 12 (11–13) | 12 (11–13) | 13 | 13 (12–13)* |
A PCA performed on 17 morphometric characters shows complete overlap between P. afer and P. swartzi, with marginal separation of P. senticeps from these two species (Figure
Factor loadings for the first two principal component (PC) axes of a PCA carried out on morphometric characters from 154 specimens of the Pseudobarbus afer s.l. complex. The most important factor loadings are in bold.
PCI | PCII | PCIII | PCIV | |
Eigenvalue | 38.3 | 19.5 | 11.7 | 5.8 |
% Variance | 38.9 | 19.9 | 11.9 | 5.9 |
Head length | 0.053 | -0.024 | 0.132 | -0.030 |
Predorsal length | 0.009 | -0.156 | 0.261 | 0.154 |
Dorsal fin base | 0.008 | 0.019 | -0.160 | -0.048 |
Dorsal fin height | 0.031 | -0.078 | 0.237 | 0.217 |
Anal fin base | 0.020 | -0.009 | -0.106 | -0.024 |
Body depth | -0.010 | -0.145 | -0.195 | 0.098 |
Body width | 0.069 | -0.075 | -0.041 | -0.001 |
Caudal peduncle length | -0.039 | 0.164 | -0.034 | 0.087 |
Caudal peduncle depth | 0.006 | -0.927 | -0.211 | -0.106 |
Posterior barbel | 0.986 | 0.022 | -0.018 | 0.052 |
Pectoral to pelvic | -0.020 | 0.076 | -0.290 | -0.187 |
Pelvic to anal | 0.000 | 0.007 | -0.073 | -0.088 |
Head depth | -0.050 | 0.049 | -0.590 | 0.712 |
Snout length | 0.039 | 0.201 | -0.517 | -0.496 |
Orbit diameter | -0.046 | 0.085 | -0.019 | 0.253 |
Post orbit | 0.089 | -0.003 | -0.015 | 0.169 |
Inter orbit | 0.052 | -0.002 | -0.175 | -0.073 |
The first three axes of a PCA performed on log transformed data explained 89.4% of the total variation in the data set, but there was no separation of the species along PCI and PCII (results not shown). Pseudobarbus senticeps was completely separated from both P. afer and P. swartzi along PCIII (results not shown), with barbel length loading heavily on this axis (0.012 eigenvalue, 9.3% of total variation, 0.789 factor loading). Specimens of P. senticeps were positively associated with PCIII, describing individuals characterised by relatively long barbels, a pattern which is similar to the one revealed using percentage data described above. In this paper, we have thus only presented PCA scatter plots recovered from analysis of percentage data.
Barbus (Capoeta) afer
Peters, 1864;
Barbus
anoplus
(non Weber, 1897):
Barbus
vulneratus
(non Castelnau, 1861):
Barbus
senticeps
Smith, 1936;
Barbus
asper
non Boulenger, 1911:
Pseudobarbus
afer
:
ZMB 5413, 3 unsexed, 78, 89, 92 mm SL, original locality uncertain, but probably the Swartkops River system (
afer means African (citizen).
Pseudobarbus afer differs from Pseudobarbus burchelli, P. burgi, P. skeltoni and P. verloreni by possession of a single pair of oral barbels. Possession of fewer and larger scales separates P. afer (29–35, mode 32 scale rows along the lateral line) from P. quathlambae (> 60 scale rows along the lateral line) and P. asper (> 35 scales along the lateral line). Lack of a mid-dorsal stripe and a relatively deeper head and body profile separates P. afer (mean head depth: 71.8 % HL (range: 66.5–78.2%); mean body depth: 25.3% SL (range: 22.5–31.6%) from the more slender bodied P. tenuis (average head depth: 65.9 % HL (range: 61.1–71.2%); average body depth: 22.4 %SL (range: 18.8–26.8%)). Lack of prominent black spots and patches on the body distinguishes P. afer from P. phlegethon. Pseudobarbus afer most closely resembles P. senticeps, P. swartzi sp. n., and P. asper. Barbel length and the number of scale rows along the lateral line separates P. afer from these three species. Short barbels which do not reach the vertical through the posterior margin of the eye and a higher number of lateral line scales (29–35, mode 32) distinguishes P. afer from P. senticeps whose barbels reach or surpass the vertical through posterior edge of eye and has fewer and larger scales (lateral line scales 25–30, mode 29; caudal peduncle scales 10–12, mode 11; Figure
Preserved colours of Pseudobarbus afer s.s topotype (
Morphometric and meristic data summarised in Table
Map of the eastern Cape Fold Ecoregion showing confirmed distributions of Pseudobarbus senticeps (turquois diamonds) restricted to the Krom River system), Pseudobarbus swartzi sp. n. (blue squares) (restricted to the Gamtoos River system and the Kabeljous and Seekoei Rivers) and Pseudobarbus afer s.s (red circles)(Baakens, Swartkops and Sundays River systems) based on recent surveys (2000–2016). Additional surveys are required to more accurately map the distribution ranges of these species in the Krom, Gamtoos, Swart, Kabeljous, Baakens and Sundays, and determine the status of populations in the Seekoei and Maitland River systems (open squares).
Body fusiform, more or less laterally compressed, with dorsal profile generally more convex than ventral profile. Body deepest around the anterior bases of the dorsal and pelvic fins. Caudal peduncle length is almost twice its depth. Head length sub-equal to body depth, snout slightly blunt, mouth sub-terminal and sickle shaped, with a single pair of simple short maxillary barbels. Barbel length shorter than orbit diameter, barbels do not surpass the vertical through posterior margin of pupil. Eyes moderately large, located dorsolaterally, closer to tip of snout than to the posterior margin of gill cover, orbit diameter shorter than snout length.
Tuberculation. Mature breeding males develop large conical tubercles on the snout and head dorsum. The bilateral clusters on the snout include 2–4 tubercles. Scattered tubercles on dorsal surface of head smaller than those on the snout. Minute tubercles develop in bands on the dorsal surface of pectoral fin rays and a row along the free edge of latero-dorsal scales.
Scales. 29–34 scale rows along the lateral line to end of hypural plate (point of flexure), 1–2 more scales to base of caudal fin. Of the 68 specimens examined, only 13 had 29–30 scale rows along the lateral line and only five specimens had 35 lateral line scale rows. The rest of the specimens (50) had 31–34 scale rows along the lateral line. Four to six scale rows between lateral line and anterior base of dorsal fin (dorsal fin origin), 3–5 scale rows between lateral line and pelvic fin origin, 3–5 scale rows between lateral line and anal fin origin, 14–16 pre-dorsal scale rows (from posterior edge of head to anterior base of dorsal fin), 12–16 circumpeduncular scales. Triangular naked patch between the gill covers and anterior base of pectoral fins, ventral scales between pectoral fin origin and pelvic fin origin reduced and embedded. Axillary scales of pelvic fin not prominent or elongate. Scales between posterior edge of head and dorsal fin origin embedded and smaller than flank scales.
Fins. Dorsal fin situated almost in the centre of the body (excluding caudal fin), origin slightly behind vertical through origin of pelvic fin, with 3–4 unbranched rays and 6–7 branched rays, distal margin straight to slightly concave, tip of depressed dorsal fin reaches within 1–2 scales to vertical through posterior base of anal fin. Pectoral fins fan-shaped, larger in males than females, with 14–17 rays, often reaches and surpasses base of pelvic fin in males, reaches 2 scales to base of pelvic fin in females. Pelvic fin with 8–9 rays, origin slightly in front of dorsal fin origin, tip of depressed pelvic fin does not reach anterior origin of anal fin, except in mature males. Anal fin with 3 simple rays and 5 (rarely 6) branched rays, distal margin almost straight to slightly convex, origin closer to anterior base of pelvic fin than caudal fin base. Caudal fin is obtusely forked, with a mode of 10+9 principal rays.
Osteology. Total vertebrae including Weberian apparatus 36–39 (mode 37), predorsal vertebrae including Weberian apparatus 11–13 (mode 12), precaudal vertebrae including Weberian apparatus 18–20 (mode 19), caudal vertebrae including Weberian apparatus 17–19 (mode 18).
Colouration (live and fresh specimens). Refer to Figure
Colouration (preserved). The bright red pigmentation on base of fins and silvery colouration fades in preservative (Figure
Pseudobarbus afer s.s. (referred to as the ‘Mandela lineage’ by
Once common and widely distributed throughout the Sundays, Swartkops and Baakens River systems, P. afer suffered severe decline in distribution and abundance, mainly due to invasion by alien predators and competitors, deterioration of water quality and loss of critical habitat. Consequently, this species (referred to as Pseudobarbus afer (Peters, 1864) by
Barbus senticeps Smith, 1936.
Barbus
afer
:
Pseudobarbus
afer
:
‘senticeps’ refers to the thorny or prickly appearance of the head (sentis a thorn, bramble, and ceps, head) of sexually mature males due to the development of distinctly pointed tubercles on the snout, along the inner edges of the nares and orbits and head dorsum (see Figure
Possession of a single pair of oral barbels separates P. senticeps from P. skeltoni, P. verloreni, P. burgi and P. burchelli. Possession of fewer and larger scales separates P. senticeps (25–30, mode 29) from P. quathlambae (> 60 scale rows along the lateral line), P. asper (35–45; mode 37–40), P. swartzi sp. n. (34–37, mode 36) and P. tenuis (32–37, mode 35–36). There is overlap (although uncommon) in lateral line scale series between P. senticeps, P. afer (29–35, mode 32) and P. phlegethon (29–37, mode 35). A lateral stripe which terminates in a triangular blotch at the base of the caudal fin and longer barbels (reaching or surpassing vertical through the posterior edge of the eye) further separate P. senticeps from P. afer (barbels do not surpass vertical through the centre of the eye). Body colour pattern distinguishes P. senticeps from P. phlegethon. Pseudobarbus phlegethon is characterised by prominent black spots and patches on the body, which are lacking in P. senticeps.
Morphometric and meristic data summarised in Table
A moderately laterally compressed, fusiform species. Cross-section of body between pectoral and pelvic fins ellipsoid. Dorsal profile of body, in lateral view, convex from snout tip to dorsal fin origin, straight and descending from dorsal fin origin to caudal fin insertion. Ventral profile, in lateral view, more or less straight or slightly convex from snout tip to anal fin origin, slightly concave and ascending from origin of anal fin to caudal fin insertion. Body deepest around anterior bases of dorsal and pelvic fin origins, progressively becoming narrower from anal fin origin towards the caudal fin. Caudal peduncle length almost twice as its depth, cross-section ellipsoid. Snout blunt or obtusely pointed. Mouth terminal, sickle shaped, its corner not reaching vertical through anterior margin of eye. A single pair of well developed, long and slender maxillary barbels present, barbel length longer than orbit diameter in most specimens. Eyes moderately large (23.5–29.5% HL), dorso-laterally positioned, and located closer to tip of snout than posterior margin of gill cover. Orbit diameter shorter than snout length.
Tuberculation. Mature breeding males develop prominent conical tubercles on the snout, along the nares and dorsal edges of the eyes. Bilateral clusters on snout include 2–4 tubercles in mature ripe males. Smaller, scattered tubercles develop on the head dorsum. A band of fine tubercles along dorsal surface of each of several anterior pectoral fin rays of mature breeding males.
Scales. Lateral line with 25–30 scales to end of hypural plate, 1–2 more scales to base of caudal fin. Four to five scale rows between lateral line and dorsal fin origin, 3–4 rows between lateral and pelvic fin origin, 3–4 scale rows between lateral line and anal fin origin, 12–15 pre-dorsal scale rows, 10–12 circumpeduncular scales. Breast scales reduced and embedded, giving a naked appearance to the region between the isthmus and base of pelvic fins. Elongated or triangular pelvic axillary scales absent. Scales between the nape and dorsal fin origin reduced and embedded.
Fins. Dorsal fin with 3–4 unbranched rays and 7 branched rays, origin slightly posterior to pelvic fin origin. Tip of adpressed dorsal fin reaches within 2–3 scales to vertical through posterior base of anal fin, distal margin straight. Pectoral fin with 13–15 rays, fan shaped, larger in males than females, tip of adpressed pectoral fin reaches and surpasses base of pelvic fin in males, reaches 2 scales to base of pelvic fin in females. Pelvic fin with 8–9 rays, origin slightly in front of dorsal fin origin, outer margin slightly convex, its tip reaching anterior origin of anal fin when depressed in males and reaches 2–3 scales to anal fin origin in females. Anal fin with 3 simple rays and 5 branched rays, distal margin almost straight to slightly convex or straight, origin closer to anterior base of pelvic fin than base of caudal fin. Caudal fin is forked, with 10+9 principal rays.
Osteology. Total vertebrae including Weberian apparatus 35–38 (mode 37), predorsal vertebrae including Weberian apparatus 11–13 (mode 12), precaudal vertebrae including Weberian apparatus 18–19 (mode 19), caudal vertebrae including Weberian apparatus 16–18 (mode 18).
Colouration (live and fresh specimens). Refer to Figure
Colouration (preserved). Dorsal surface of alcohol preserved specimens dark grey or black, sides and belly lighter. Distinct black lateral stripe from posterior margin of operculum terminating into a black triangular blotch of pigment at the base of the caudal peduncle. Red pigmentation at the base of fins disappears in preserved specimens (Figure
Pseudobarbus senticeps (referred to as the ‘Krom lineage’ by
Pseudobarbus senticeps inhabits perennial mountain streams with clear to peat stained water, cobble and pebble substrates.
Pseudobarbus senticeps (referred to as Pseudobarbus sp. “afer Krom” by
Gamtoos redfin.
The species is named after Dr Ernst R. Swartz for his contribution to the biogeography and systematics of Pseudobarbus and the role that he played in mentoring students working on the systematics and biogeography of southern African freshwater fishes.
Possession of a single pair of oral barbels separates P. swartzi sp. n. from P. burchelli, P. burgi, P. skeltoni and P. verloreni all with two pairs. It differs from P. quathlambae by having larger scales and fewer scale rows along the lateral line (P. swartzi: 35–37, mode 35–36 lateral line scales; P. quathlambae: > 65 scales along lateral line). Pseudobarbus swartzi and P. senticeps show some overlap in barbel length (Figure
General appearance and colouration is shown in Figs
Tuberculation. Mature breeding males develop large conical tubercles on the snout and along the dorsal edge of the nares and eyes. Bilateral clusters on snout include 2–4 tubercles in mature ripe males. Smaller, scattered tubercles develop on the head dorsum. Bands of fine tubercles along dorsal surface of pectoral fin rays.
Scales. Scale rows along lateral line 34–37 (mode 36) ending at hypural, with 1–2 more scales to base of caudal fin; 6–7 (mode 6) scale rows between lateral line and dorsal fin origin; 4–5 (mode 5) rows between lateral line and pelvic fin origin, 5 rows between lateral line and anal fin origin, 16–20 (mode 17–18) pre-dorsal scale rows, 13–17 (mode 16) scale rows around caudal peduncle. Triangular naked patch between the gill covers and anterior base of pectoral fins, scales between pectoral fin origin and pelvic fin origin reduced and embedded. Axillary scales of pelvic fin not prominent or elongate. Scales between posterior edge of head and dorsal fin origin embedded and smaller than flank scales.
Fins. Dorsal fin is inserted about mid-body (excluding caudal fin), origin slightly behind vertical through origin of pelvic fin, with 3–4 unbranched rays and 7 branched rays, distal margin straight to slightly, posterior tip of depressed dorsal fin does not reach vertical through posterior base of anal fin. Pectoral fins fan-shaped, larger in males than females, with 14–16 rays, tip of depressed pectoral fin almost overlapping with pelvic fin in large males, reaches 2 scales to base of pelvic fin in females. Pelvic fin with 8 rays, origin slightly in front of dorsal fin origin, tip of depressed pelvic fin not reaching anterior origin of anal fin, except in mature males. Anal fin with 3 simple rays and 5 branched rays, distal margin straight to slightly convex, origin closer to anterior base of pelvic fin than caudal fin base. In mature males, tip of depressed pelvic fin often surpass point of anal fin origin while they only reach up to the anus in females. Caudal fin is forked, with 10+9 principal rays.
Colouration (live and fresh specimens). Refer to Figure
Colouration (preserved). Alcohol preserved specimens are dark greyish above the lateral line, light grey or whitish below the lateral line and ventrally, breast of freshly preserved specimens silvery (Figure
Osteology. Total vertebrae including Weberian apparatus 37–38 (mode 37), predorsal vertebrae including Weberian apparatus 12–13 (mode 13), precaudal vertebrae including Weberian apparatus 19–20 (mode 20), caudal vertebrae including Weberian apparatus 17–18 (mode 18).
Pseudobarbus swartzi sp. n. occurs in the Kougaberg, Baviaanskloofberg and Elandsberg tributaries of the Kouga and Groot sub-catchments of the Gamtoos River system, and the Kabeljous and Swart River systems which discharge into St Francis Bay (Figure
Pseudobarbus swartzi inhabits perennial mountain streams with clear or peat stained water as well as cobble, pebbles and boulders.
Remnant populations of the species are under severe threat from multiple human impacts including habitat degradation, complete water abstraction and potential invasion by alien fish predators and competitors that are now dominant in mainstem sections of the rivers (
Pseudobarbus afer:
Pseudobarbus swartzi: AC16AL01 (
The three species recognised in the present study exhibit subtle morphological differences and show marginal overlap in some meristic (i.e. scale) counts. This explains why these species were previously considered to represent one widespread but variable species (
These morphologically very similar species can be distinguished based on a combination of lateral line scale counts, circumpeduncular scale counts, body colour pattern and length of oral barbels. Pseudobarbus senticeps differs from both P. afer and P. swartzi by having fewer (i.e. larger) scales along the lateral line (mode 29), fewer scales around the caudal peduncle (mode 11) and a distinct lateral stripe that terminates in a triangular blotch at the base of the caudal fin. This colour pattern becomes more pronounced in preserved specimens. Pseudobarbus senticeps further differs from P. afer by having distinctly long barbels that reach or surpass vertical through the posterior edge of the eye. Barbels and other external features such as fins are however susceptible to degradation particularly in habitats affected by waste water discharge. Caution should therefore be exercised, and it is recommended that identification of the species should not be based on barbel length alone, but should be used in combination with scale counts and colour pattern. Pseudobarbus swartzi has smaller scales, i.e. more scales along the lateral line (mode 36) and around the caudal peduncle (mode 16) compared to P. afer. (mode 32 and 12, respectively). Pseudobarbus swartzi and P. afer further differ in scale pigmentation pattern. In P. afer, the melanophores form a semi-circular band around the centre of the scale, while the basal segment of the exposed area and the distal margin are not pigmented. This produces a distinct mesh or net-like pattern which is more pronounced on the latero-ventral scales (see Figure
The close morphological similarity observed among the three allopatric and genetically divergent species reported in the present study has also been reported for other riverine fishes, including the African butterfly fish, Pantodon buchholzi, from the Niger and Congo river systems (Lavoué et al. 2010) and the dwarf loach, Cobitis brevifasciata (previously Kichulchoia brevifasciata), from the Goheung Peninsula in South Korea (
The CFE experienced a complex history that left a perceptible imprint in the distribution and diversity of stream fishes in the region (see
a An illustration of part of the Cape Fold Belt showing the drainage of the Gamtoos River system, sites of drainage capture of adjacent river systems and historical direction of flow of captured rivers (modified from Skelton, 1980) b Part of the eastern Cape Fold Ecoregion showing reconstructed Palaeoriver systems during the Last Glacial Maximum (modified from
Sea-level changes offer another alternative explanation for the observed genetic and distribution patterns of redfins in the eastern CFE. Palaeoriver reconstructions for this region show that the Pliocene marine transgression resulted in fragmentation of the major river systems (the Krom, Gamtoos, Swartkops and Sundays), while smaller coastal systems (e.g. the Swart, Seekoei, Kabeljous, Van Stadens, Maitland, Baakens and Coega) were drowned and were presumably unavailable to freshwater taxa during this period (see
As with many other endemic stream fishes in the CFE, there is need for immediate intervention measures to ensure future survival of P. afer, P. swartzi and P. senticeps. As with elsewhere in the CFE (see
This work was supported by the National Research Foundation (NRF) of South Africa under the Foundational Biodiversity Information Programme: Biodiversity surveys in priority inland areas (IBIP) grants (grant reference no. IBIP-BS13100251309). The authors acknowledge that opinions, findings and conclusions or recommendations expressed in this publication generated by the NRF supported research are that of the authors and that the NRF accepts no liability whatsoever in this regard. We thank Rodger Smith, Roger Bills, Veer Bills, Bosupeng Motshegoa, Wilbert Kadye, and Nkosinathi Mazungula for assistance with field collections, Nkosinathi Mazungula for taking the radiographs and the Department of Economic Development, Environmental Affairs and Tourism (Eastern Cape Province) for issuing a research permit (permit numbers: CRO 88/15CR and 01/31447). Gavin Gouws, Leah Sloman, Seshnee Reddy and Sisanda Sibanga helped with laboratory work.