Pseudobarbus verloreni, Chakona, Albert, Swartz, Ernst R. & Skelton, Paul H., 2014

Chakona, Albert, Swartz, Ernst R. & Skelton, Paul H., 2014, A new species of redfin (Teleostei, Cyprinidae, Pseudobarbus) from the Verlorenvlei River system, South Africa, ZooKeys 453, pp. 121-137 : 126-130

Taxon classification Animalia Cypriniformes Cyprinidae

Pseudobarbus verloreni sp. n. Figure 3, Table 4

Proposed common names.

Verlorenvlei redfin (English), Verlorenvlei rooivlerkie (Afrikaans).

Holotype.

South Africa: Western Cape Province: SAIAB186092, mature male, 70.8 mm standard length (SL), collected from the Verlorenvlei River, 20 m upstream from railway at the Het Kruis bridge on R365 (32.60179000 S, 18.75039000 E) on 13 March 2012 by E. Swartz and W. Bronaugh, using a seine net. Hologenetype: GenBank number KM366106.

Paratypes

(n =46). South Africa: Western Cape Province: SAIAB192542 (n=3, 53.3-70.8 mm SL), same data as for holotype; SAIAB59808 (n=10, 40.1-46.9 mm SL), collected from the Verlorenvlei River (32.74560165 S, 18.81780052 E) on 22 January 1999 by R. Bills and D. Naran using a seine net and D-net; BMNH2014.2.26.1-2 (n=2, 52.8-58.2 mm SL), USNM427302 (n=2, 53.4-56.8 mm SL), MRAC-B4-03-P-1-2 (n=2, 53.0-54.5 mm SL), same data and collectors as SAIAB59808, SAIAB121038 (n=10, 34.0-68.0 mm SL) collected from the Verlorenvlei River in 1973 by P. Skelton, C. Gaigher and D. Heard; SAIAB121039 (n=17, 41-57 mm SL) collected from the Kruis River, Verlorenvlei, in 1973 by P. Skelton, C. Gaigher and D. Heard. Paragenetype: SAIAB192542, GenBank number: KM366107.

Diagnosis.

The new species can be distinguished from its congeners by distinct linear speckles above and below the lateral line, anterior barbels minute and much smaller than eye diameter, lips unretracted, and a cartilaginous fig absent.

Description.

Proportional measurements and meristic characters are presented in Table 4. The body is fusiform, more or less laterally compressed, with a conspicuous lateral stripe from the posterior edge of the head terminating in a dark spot at the base of the caudal peduncle. The lateral band is more pronounced in juveniles and sub-adults, but is less conspicuous in adults. Distinct linear speckles are present on the abdomen. The head is relatively small and slightly depressed; head length is almost equal to body depth. Two pairs of barbels, rostral (anterior) barbels minute and much smaller than eye diameter; maxillary barbels are rooted at the corner of the mouth are longer than rostral barbels and are equal or smaller than eye diameter. Eyes are relatively large, located dorsolaterally, closer to the tip of the snout than the caudal margin of the operculum, interorbital space is flat. Mouth is sub-terminal, lower lip is unretracted and lacks a cartilaginous fig. Snout is relatively short, only few nuptial tubercles present (observed in only one individual; Figure 4) or tubercles are completely lacking.

Counts for the holotype are given in a separate column in Table 4. Dorsal fin of the new species has 3 unbranched and 7 or 8 branched rays, distal margin almost straight, anterior base of dorsal fin inserted directly above or slightly in front of the origin of pelvic fins. Origin of dorsal fin inserted almost midway between tip of snout and base of caudal fin. Pectoral fins with 13 to 16 rays, shorter than head length, reaching beyond halfway to pelvic fin origin. Pelvic fin with 7 to 9 rays, shorter than head, posterior edge gently rounded, reaching the anus in males and within one or two scale rows to the anus in females. Anal fin with 3 or 4 unbranched and 5 branched rays, distal margin almost straight or gently rounded, origin inserted closer to origin of pelvic fin than base of caudal fin. Caudal fin forked, shorter than head length. Genital opening situated adjacent to anterior base of anal fin.

Scales moderately large; lateral line complete, majority of specimens have 32 scales along lateral line (range 29-36); 5-6 (mode 6) scale rows between dorsal fin origin and lateral line; 4-5 (mode 5) scale rows between pelvic fin origin and lateral line; 4-5 (mode 4) scale rows between lateral line and anal fin origin; 12-16 (mode 12) circumpeduncular scale rows. Predorsal scale rows 13-18 (mode 16), embedded in skin, smaller than flank scales. Patch between head and posterior base of pectoral fins naked; scales between posterior base of pectoral fins and anterior base of pelvic fins smaller than flank scales and embedded. Pelvic fins lack prominent or elongate axillary scales. Scales radiately striated.

Nuptial tubercles have only been observed in one individual of Pseudobarbus verloreni (Figure 4). The bilateral placement of tubercles on the snout is typical for Pseudobarbus , but the low number (only 4 tubercles in total) of the Pseudobarbus verloreni individual in Figure 4 is unusual. The other members of the double barbeled redfin group develop multiple prominent conical tubercles on the snout and head dorsum during the breeding season (see Chakona and Swartz 2013). Additional sampling during the breeding season is required to determine whether this is a consistent development pattern for Pseudobarbus verloreni .

Colouration.

Live colouration is golden-tan dorsally and laterally, becoming lighter and more silver ventrally (Figure 3c). In adults (above 40 mm SL), base of fins is pale red or yellowish-orange in some specimens. Alcohol preserved specimens have conspicuous linear speckles above and below the lateral line.

Osteology.

Radiographs of the holotype (SAIAB 186092) and paratypes show that the species has osteology typical of all Pseudobarbus species. Compared to other cyprinids, particularly those within the genus Barbus , supraneural bones are less developed or extremely vestigial in all members of the genus Pseudobarbus (Skelton, 1988). Skelton (1988) did not record any supraneural bones in Pseudobarbus specimens (n=53) from the Verlorenvlei River system (herein described as Pseudobarbus verloreni sp. n.). Vertebrae counts for the holotype are given in a separate column in Table 4. Total number of vertebrae in 47- specimens investigated in the present study ranged from 34-37: 34 (n=1), 35 (n=3), 36 (n=31) or 37 (n=12) comprising 18-21 (mode 19) precaudal, 19-22 (mode 20) pre-anal, 10-13 (mode 11) predorsal and 16-19 (mode 17) caudal vertebrae (Table 4).

Additional information.

SAIAB59813, juveniles (n=68, 13.5-28.4 mm SL) and adults (n=3, 59.3-64.6 mm SL), collected from the Verlorenvlei River, near Grootfontein farm (32.39830017 S, 18.47419930 E) on 23 January 1999 by R. Bills and D. Naran using a seine net and D-net. Juveniles and sub-adults of Pseudobarbus verloreni have a conspicuous lateral band, while the lateral band is either less prominent or interrupted by linear spots in juveniles and sub-adults of the other double barbeled Pseudobarbus species. The new species has three rows of pharyngeal teeth, teeth pattern 2.3.5-5.3.2 (observed in 3 adults; SAIAB59813); teeth with asymmetrical crowns and hooked at their tips. Pseudobarbus verloreni sp. n. has the longest intestine relative to standard length compared to all the Pseudobarbus species ( Skelton 1988: Figure 25Bc).

Comparisons.

Pseudobarbus verloreni sp. n. is distinguished from all other species of Pseudobarbus (except Pseudobarbus skeltoni , Pseudobarbus burchelli and Pseudobarbus burgi ) by the presence of two pairs of oral barbels. The new species is distinguished from Pseudobarbus skeltoni , Pseudobarbus burchelli and Pseudobarbus burgi by having a deeper body relative to standard length, smaller anterior barbels and shorter snout relative to head length (Table 4). The new species is distinguished from Pseudobarbus skeltoni by having a sub-terminal mouth (versus terminal in adults of the latter species) and a smaller head relative to standard length (Table 4). Pseudobarbus verloreni is distinguished from Pseudobarbus burchelli and Pseudobarbus skeltoni by a deeper head, wider distance between the eyes (inter-orbit), larger eye relative to head length, shorter posterior barbel relative to head length, wider post-orbit distance, shallower caudal peduncle and generally fewer scales along the lateral line. Pseudobarbus verloreni is distinguished from Pseudobarbus burchelli and Pseudobarbus burgi by lack of cartilaginous fig on lower lip and having unretracted lips. The new species is distinguished from Pseudobarbus burgi by its longer head, longer pre-dorsal length, shorter caudal peduncle and larger eye (Table 4).

Reproduction.

Unknown, but spawning possibly occurs around October-December, based on the general patterns of congeners.

Distribution and habitat.

Pseudobarbus verloreni is a lowland species that is restricted to the Verlorenvlei River system on the west coast of South Africa (Figure 5). The morphological features of two juvenile specimens of Pseudobarbus collected from the Langvlei River by Thorne and Cambray in 1986 (SAIAB 130464) are consistent with juveniles of the new species, and are thus assigned to Pseudobarbus verloreni . The Langvlei River population is likely to have been extirpated, as no specimens of Pseudobarbus have been collected during more recent surveys (2001-2012). The major impact on this river is excessive water extraction that causes the river to dry up completely during the dry season. The Verlorenvlei River system has a gentle gradient and slow to moderate flow for much of the year. The water is highly turbid during the rain season (winter months) when water volume and flow velocity is high, but it becomes less turbid during low flow periods. Most sections of the river system recede into a series of isolated pools during the dry season, especially during late summer and autumn. The bottom substratum is predominantly sand, silt and mud. This is in contrast with the majority of the streams in the CFR that are associated with the Cape Fold Mountains with steeper gradients, clear water, moderate to fast flow throughout the year and rocky substratum. The species was possibly widespread throughout the Verlorenvlei and Langvlei River systems in the past, but numbers likely declined during the last century due to predation and competition from introduced fish species and habitat degradation (see below).

Etymology.

The species is named after the Verlorenvlei River system to which it is now confined.

Conservation.

The Verlorenvlei redfin was listed as Endangered during the most recent IUCN assessment by Tweddle et al. (2009). The presence of non-native predatory black bass Micropterus spp and potential competitors, banded tilapia Tilapia sparrmanii , Mozambique tilapia Oreochromis mossambicus and common carp Cyprinus carpio , habitat degradation and excessive water withdrawal for agricultural purposes pose the greatest threat to the survival of this species. Protection of critical habitats and establishment of sanctuaries are some of the most immediate conservation measures required to prevent further decline. The effectiveness of current protected areas in conserving Pseudobarbus verloreni is limited because they largely encompass upland areas where this species does not occur. Long-term measures to protect and prevent extinction of this species may have to include eradication of alien fishes and the construction of barriers to prevent re-invasion where feasible and restoration of existing habitats to facilitate recovery.