Pseudobarbus agulhas Zarei, Martin & Chakona, 2025

Zarei, Fatah, Martin, Melissa B., Skelton, Paul H. & Chakona, Albert, 2025, Systematic review of Pseudobarbus burchelli (Teleostei, Cyprinidae), with revalidation of P. vulneratus and description of a new species, Zoosystematics and Evolution 101 (3), pp. 1271-1296 : 1271-1296

Pseudobarbus agulhas Zarei, Martin & Chakona sp. nov.

English name: Agulhas redfin Afrikaans name: Agulhas-rooivlerkie Figs 10 , 11

Type materials.

Holotype. • SAIAB 246287 (tag number H 1), 69.9 mm SL, Grashoek River , Heuningnes River system, South Africa, -34.579194, 19.967305, collected by A. Chakona, N. Mazungula & X. Mathebula, 21 February 2024.

Paratypes (n = 19). • SAIAB 237284 (tag numbers H 2 – H 9), 8 specimens, 46.4–80.4 mm SL, same data as for holotype . • SAIAB 246289 (tag numbers X 72 – X 78), 7 specimens, 59.6–65.7 mm SL, Grashoek River , Heuningnes River system, South Africa, -34.590769, 19.994032, collected by J. Martens, Abraham & S. Thorne, 24 March 1983 . • SAIAB 201020 (tag numbers X 68 – X 71), 4 specimens, 45.6–50.4 mm SL, Grashoek River , Heuningnes River system, South Africa, -34.574, 19.948, collected by A. Chakona & E. Swartz, 18 February 2009 .

Additional material

(n = 15). • SAIAB 246288 (tag numbers X 52 – X 67), 15 specimens, 52.7–88.1 mm SL, Karingmelksriver , Klein River System, South Africa, -34.395137, 19.709277, collected by A. Chakona, A. Anderson, M. Mtshintshi, S. Anele Ngema & N. Khusi, 20 & 21 December 2023 .

Diagnosis.

Pseudobarbus agulhas sp. nov. can be distinguished from all other known species in the genus through the following set of characters: subterminal mouth with two pairs of barbels; 14–16, usually 15 scale rows around the caudal peduncle; 15–18, usually 16–17 predorsal scales; lateral line to dorsal fin scales 6–8, usually 6–7; 19–21, usually 20 precaudal vertebrae; 14–16 pectoral fin rays; interorbital width 32.3–38.7 % HL; anterior barbel length 8.4–24.8 % HL; orbit diameter 18.4–26.4 % HL; absence of linear stripes on the body; presence of dorsal and mid-lateral spots and blotches; tuberculation of head in mature breeding males: large to small conical / blunt tubercles, 3–4 in each snout cluster, single row above each naris with 0–3 tubercles per cluster, and single row above each orbit with 1–2 tubercles in each cluster; and 0–2, usually 1 tooth in the outer pharyngeal tooth row. Additionally, Pseudobarbus agulhas sp. nov. is the sole redfin species found in the Heuningnes and Klein River systems.

Description.

All morphometric values in the text are listed with the holotype first, followed by paratypes and additional materials in parentheses if they differ.

General morphology. Body proportions and meristics are given in Table 3 . Body moderately elongate, fusiform, with dorsal profile generally more convex than ventral profile, maximum body depth 4.0 (3.6–4.5) in SL, body laterally compressed. Caudal peduncle shallow, its depth 0.5 (0.4–0.7) times its length. Head long, length 3.6 (3.2–3.9) in SL, depth at eye 6.7 (5.1–7.5) in SL and 0.6 (0.5–0.8) times maximum body depth. Postorbital profile steep. Snout short, oblique, convex, longer than eye, length 1.7 (1.2–1.9) times eye diameter and 2.8 (2.7–3.3) in head length. Eye diameter 4.7 (3.8–5.4) in head length, and dorsolateral, not extending above dorsal profile. Interorbital wide and flat, 1.8 (1.3–2.0) times orbit diameter. Mouth sub-terminal, sickle-shaped, its corner reaching vertical through middle of nares. Mouth with two pairs of well-developed barbels; anterior barbel length 0.8 (0.4–1.3) times orbit diameter, ranging from significantly short of anterior eye margin to extending to the eye midpoint. Posterior barbel length 1.5 (0.9–2.1) times eye diameter, ending between the pupil and slightly beyond preopercular margin.

Tuberculation. Adult breeding males typically with few conical or blunt tubercles of various sizes on their snouts and the tops of their heads (Fig. 6 ). Bilateral clusters of tubercles, ranging from large to small (3–4, usually 3), are found on the snout. A row of tubercles, varying in size from large to small and resembling those on the snout, extends above each naris (0–3, usually 1–2 per cluster) to the anterodorsal edge of the orbit. A single row of 1–2 tubercles (usually 2, with the anterior one being larger) along the dorsal edge of each orbit. The anterior dorsal area is typically naked but may include a few small or tiny tubercles. The posterior dorsal area is either naked or has a few scattered tiny tubercles. Minute tubercles are present either as a line along the free edges of the scales or scattered across the surface of the body scales located above the lateral line. Lines of minute tubercles are found on the fin rays, though they are less prominent on the caudal fin rays.

Scales. LL 34–39 (holotype: 37; other material: 34: 3, 35: 5, 36: 8, 37: 7, 38: 7, 39: 3), LD 6–8 (holotype: 7; other material: 6: 16, 7: 17, 8: 1), LP 4–6 (holotype: 4; other material: 5: 32, 6: 2), LA 4–6 (holotype: 4; other material: 4: 2, 5: 27, 6: 5), CP 14–16 (holotype: 15; other material: 14: 9, 15: 20, 16: 4), PDS 15–18 (holotype: 15; other material: 15: 4, 16: 15, 17: 11, 18: 3). Predorsal scales and ventral scales between pectoral fin origin and pelvic fin origin embedded and smaller than flank scales. Triangular area between the gill cover and anterior base of pectoral fin naked or scaled.

Fins. Dorsal fin rays iv / 7 – iv / 8 (holotype: iv / 7; other materials: iv / 7: 32, iv / 8: 2); anal fin rays iv / 5 – iv / 6 (holotype: iv / 5; other materials: iv / 5: 33, iv / 6: 1); pectoral fin rays 14–16 (holotype: 14; other materials: 14: 20; 15: 13; 16: 1); pelvic fin rays 8–9 (holotype: 8; other materials: 8: 32, 9: 2); caudal fin branched rays 17–18 (holotype: 17; other materials: 17: 33, 18: 1). The dorsal fin is positioned nearly at the centre of the body (excluding the caudal fin), with its origin slightly behind the vertical line through the pelvic fin’s origin. The distal margin is straight to slightly concave, and in tubercled specimens, the tip of the depressed dorsal fin nearly reaches the vertical line at the posterior base of the anal fin; in other specimens, it falls 0.5–1.5 scales short of that point. The pectoral fin is fan-shaped and varies in length, extending to or beyond the origin of the pelvic fin in tubercled specimens; in other specimens, it falls 0.5 to 2 scales short of the pelvic origin. The origin of the pelvic fin is slightly ahead of the dorsal fin origin, with variable length. The tip of the depressed pelvic fin either reaches or exceeds the anal fin origin or is 0.5 to 3 scales short in both sexes. The distal margin of the anal fin is nearly straight to slightly convex, with its origin located nearer to the origin of the pelvic fin than to the base of the caudal fin. The caudal fin is forked.

Osteology (n = 16). Vertebral column including Weberian apparatus and urostyle: total vertebrae 36–37 (holotype: 37; other materials: 36: 6, 37: 9), predorsal vertebrae 11–12 (holotype: 11; other material: 11: 8, 12: 7), precaudal vertebrae 19–21 (holotype: 19; other material: 19: 3, 20: 11, 21: 1), caudal vertebrae 16–18 (holotype: 18; other material: 16: 5, 17: 9, 18: 1).

Gill rakers (n = 5): 3–4 + 1 + 10 – 12 (epibranchial: 3: 1, 4: 4; angle: 1: 5; ceratobranchial: 10: 2, 11: 2, 12: 1).

Pharyngeal teeth (n = 5). Three rows of pharyngeal teeth, teeth pattern 1–2, 3, 4–5 + 4, 2–3, 0–1. The distribution frequency of pharyngeal teeth is given in Table 4 .

Colour of live specimens.

Refer to Fig. 11 for general live colouration. The dorsal surface of the body, above the lateral line, is olive-brown, becoming darker toward the dorsal region. Below the lateral line, the body is marked with blemished silvery-white, gradually transitioning to white on the ventral surface. The base of the fins is bright scarlet, with the colour becoming less pronounced in the caudal fin. The mid-lateral band is indistinct, while a large triangular mark is located at the base of the caudal fin. The dorsum is adorned with sooty dark brown spots and blotches, and a series of irregular spots may also be visible along the posterior half of the body.

Colour of preserved specimens.

Refer to Fig. 10 for colouration observed in preserved specimens. The flanks exhibit a distinct or usually indistinct dark mid-lateral band that tapers into a triangular shape at the base of the caudal fin. The dorsal head and body are olive brown or dark brown, fading to a lighter colour ventrally. Typically, there are dark spots and blotches along the flanks and on the dorsal half of the body, including a mid-lateral series of irregular spots. However, in some larger specimens and breeding males with tubercles on their heads, these blotches and spots may be absent.

Distribution and ecology.

Pseudobarbus agulhas sp. nov. is characterised by a limited distribution, being found exclusively in the Heuningnes and upper sections of the Klein river system (Fig. 2 ; Swartz et al. 2009, 2014; Chakona et al. 2013). The species is found in pools and streams, with fry and juveniles occurring in large shoals as opposed to the adults collecting in small groups. As omnivores, they feed on algae and small invertebrates. Like P. vulneratus , it breeds during summer, spawning in riffles above pools, coexisting with Cape kurper [ Sandelia capensis (Cuvier, 1829) ] and Cape galaxias [Galaxias zebratus ( Castelnau, 1861)] ( Skelton 2024).

Conservation.

In the latest IUCN Red List Assessment for South African freshwater fish, this lineage was classified as Endangered (EN) ( Chakona et al. 2022). The populations are threatened due to water extractions for domestic and agricultural use, as well as introduced alien fish such as the bluegill ( Lepomis macrochirus Rafinesque 1819 ) and bass ( Micropterus spp. ).

Etymology.

The specific epithet agulhas is derived from Cape Agulhas, the southernmost point of the African continent, where the Atlantic and Indian oceans meet. This name recognises the region’s distinct biogeographic boundary and ecological significance, which supports a rich diversity of both marine and freshwater species. The Heuningnes River, the primary habitat and distribution range of the species, is also located within the Agulhas region. A noun in apposition.

Figures

Figure 2. Distribution map of all double-barbeled Pseudobarbus species / lineages based on genetic data (this study; Bloomer and Impson 2000; Tsigenopoulos et al. 2002; Chakona et al. 2013, 2014; Swartz et al. 2014).

Figure 6. A. Diagrammatic representation of the head tubercle pattern in a mature breeding male redfin: a, cluster on snout; b, row above nares; c, row above orbit; d, anterior dorsal cluster; e, posterior dorsal cluster (modified from Skelton 1988). Tuberculation of head in mature breeding males of B. Pseudobarbus burchelli (SAIAB 126387, neotype, 102 mm SL, Tradouw catchment, Breede River system); C. P. skeltoni (SAIAB 187243, holotype, 158.2 mm SL, Riviersonderend River upstream, Breede River system); D. P. vulneratus (SAIAB 210457, 63.6 mm SL, Duiwenhoks River system), and E. P. agulhas sp. nov. (SAIAB 246288, 66.4 mm SL, Klein River system).

Figure 10. Pseudobarbus agulhas sp. nov., A, B. SAIAB 246287, holotype, 69.9 mm SL, Grashoek, Hueninghes River system; C, D. SAIAB 246288, 88.1 mm SL, Klein River system.

Figure 11. Live specimens of Pseudobarbus agulhas sp. nov. from the Grashoek River, Heuningnes River system. A. SAIAB 246287, holotype, 69.9 mm SL; B. SAIAB 237284 (tag H 7), paratype, 51.0 mm SL; C. SAIAB 237284 (tag H 3), paratype, 77.4 mm SL.