Poroderma africanum

Poroderma africanum (Gmelin, 1789)

(Fig. 1, Table 1)

Squalus africanus Gmelin, 1789: 1494.

Squalus vittatus Shaw and Nodder, 1798: 346 (in Garman 1913: 70, and Compagno 1984b: 347), although attributed to Walbaum 1792: 516, by Fowler 1941: 40.

Scyllium africanum: Cuvier 1816: 359; Müller and Henle 1838 -1841: xxi, 12; Smith 1849: 9; Duméril 1853: 82; Günther 1870: 405; Bleeker 1878: 1, 8; Sauvage 1891: 6, 511; Gilchrist 1902: 103; Gilchrist 1914: 111; Lampe 1914: 209.

Squalus striatus Forster in Lichtenstein, 1844: 407 (in Garman 1913: 70, Fowler 1941: 40, and Compagno 1984b: 347).

Scyliorhinus africanus: Regan 1908: 456; Bigelow and Schroeder 1948: 197.

Scylliorhinus africanus: Thompson 1914: 136; Gilchrist and Thompson 1916: 270; Gilchrist 1922: 4; Barnard 1925: 39; Barnard 1927: 1013; Barnard 1948: 342.

Poroderma africana: Wallace et al. 1984: 159; Buxton et al. 1984: 186.

Type Series and Locality. No types exist for P. africanum. “Habitat in mari africano” (from African seas).

Diagnosis. P. africanum is characterised, and distinguished from its congener, by the presence of bold, thick black stripes (Fig. 1). The snout of P. africanum is wider, shorter and more broadly pointed than in P. pantherinum; head width 13.5% TL. The upper labial furrow is shorter and thicker than in P. pantherinum; upper labial furrow length 0.6 times its width. The nasal barbels of P. africanum are stouter than P. pantherinum, rarely reach the upper lip and do not overhang the mouth; nasal barbel length 0.5 times nostril width.

Description. Morphometric and meristic data are given in Table 1. Since no type material is available for P. africanum, the following is based on specimens examined by the author (see Study material). P. africanum is a robust shark and the larger of the Poroderma sharks. Precaudal length 1.25 times the preanal length; snout wide and broadly pointed; distance from snout to 2nd dorsal fin origin 1.3 times the distance from snout to 1st dorsal fin origin; mouth width 2.1 times the preoral length; prenarial length 0.85 times the mouth length; nasal barbels elongated, but not extending over the upper lip and usually not reaching the upper lip; 2nd dorsal base length 0.9 times dorsal caudal space; distance from snout to pectoral fin origin about equal to the caudal dorsal margin length; pelvic fin base length about equal to pectoral fin base length; height of pectoral fin 1.9 times that of the pelvic fin; distance between the pelvic and anal fins 1.2 times the length of the anal fin base. Vertebral counts: 42-45 monospondylous, 30-52 precaudal diplospondylous, 30-50 caudal diplospondylous vertebrae. Dental formula: upper jaw (left) 20-24, (right) 18-25; lower jaw (left) 16-24, (right) 14-24. Spiral valve turns: 9-12.

Size and Sexual Maturity. P. africanum is a robust scyliorhinid and one of the larger species belonging to this family. From the current study, it was determined that this shark grows to at least 109 cm TL and weigh at least seven kilograms. The SA angling record for this species is 7.9 kg (Wright et al. 2000). Males are embryonic at 149 mm TL, juvenile at 163 mm TL to 550 mm TL, and mature at 725 mm TL to 972 mm TL. Females are embryonic at 110 mm TL to 169 mm TL, juvenile at 251 mm TL to 447 mm TL, adolescent at 667 mm TL to 865 mm TL, and mature at 785 mm TL to 969 mm TL. There appears to be little sexual dimorphism in this species, with both sexes growing to approximately one metre, although the males mature at a smaller size than the females.

Colouration. Dorsal background colouration is usually pale to moderate grey, and occasionally dark grey. Prominent black stripes originating on the snout, running parallel to the body axis on the dorsal surface, and terminating at the caudal peduncle; one stripe on dorsal midline and at least two stripes laterally, with a third stripe occasionally present; the third lateral stripe variably extends from under the snout, continuing under the eye, under, over, or above the branchial region, terminating at the pectoral origin, or continuing over the pectoral base, and variably continuing from the pectoral insertion to the pelvic origin; and is often much paler than the other stripes; not infrequently, one or both of the main lateral stripes bifurcate on the head, typically just behind the eye; specimens have also been examined that have the centres of the main stripes pale, giving the impression of two stripes, an excellent example of this is illustrated in Branch et al. (1999); some individuals, possess one or two (rarely more) large black spots randomly scattered on the dorsal surface. Ventral colouration is pale grey to white, and there is usually an abrupt margin between grey and white, when white is present. When the ventral surface is white, occasionally pale grey spots are present. All fins lack markings. The colour pattern of the embryo is generally the same as that of the adult. Some individuals may be considerably paler than that of adults, and in some, the stripes may be a very dark brown (Fig. 1C).

Although not observed by the author, albinism has been reported to occur in this species. Barnard (1948) reported a moderately sized albino P. africanum caught in Kalk Bay (False Bay, Western Cape). This specimen was preserved by Barnard, but could not be located for this study.

Comparison with other species. P. africanum is stockier than P. pantherinum at all maturity stages for both sexes, and grows to a greater total length. This species has bold thick dark stripes running anteroposteriorly, with occasional spotting, but the latter is never to the extent of P. pantherinum. There are never any rosettes, and the background dorsal colouration is never darker than dark grey.

Remarks. There are no types known for P. africanum (Eschmeyer 1998), although Gmelin (1789: 1494) did refer to an individual “2½ pedes longus”. According to the International Code of Zoological Nomenclature (ICZN), a neotype should be designated only in circumstances where it is necessary to stabilise nomenclature, and a neotype may not be designated as a matter of curatorial routine (Articles 75.1 and 75.2 of the ICZN 1999). P. africanum is a readily identifiable shark and is unlikely to be confused with any other species. The author has not come across any evidence of taxonomic confusion relating to the identification or nomenclatural stability of this species, therefore a neotype should not be designated for this species.

It should be noted that Gmelin’s 13th edition of Systema Naturae was published in a series of parts beginning in 1788, and the entire work is occasionally credited with that date. However, the different parts were published over several years through to 1793, and the section containing the description of S. africanus was published in 1789 (Hopkinson 1907).

The proportional dimensions and vertebral counts given here (Table 1) are closely matched by those given by Bass et al. (1975). Vertebral counts given by Springer (1979) and Compagno (1988), also agree with the current study. Bass (1973) described the allometry in a number of morphometric measurements for P. africanum, and indicates that some of the head measurements, in particular, are subject to allometric growth. P. africanum exhibits both ontogenetic heterodonty, between adolescent and mature specimens of both sexes, and sexual heterodonty (M. Marks pers. comm.). The teeth of this species are illustrated by Bass et al. (1975), who also found slight ontogenetic and sexual heterodonty. Compagno (1988) described strong gradient heterodonty for all species of Poroderma, and also noted weak sexual heterodonty. Tooth counts provided here agree with those given by Fowler (1925), Compagno (1988) and Marks (pers. comm.); however, both Compagno and Marks reported greater maximal tooth counts in both jaws compared to those found here. The denticles of P. africanum have been described by Bass et al. (1975) and Compagno (1988), and illustrated by Bass et al. (1975). Embryos and hatchlings have two enlarged rows of denticles on the dorsal surface, probably to aid in release from the egg case during hatching, and are visible on small free-swimming individuals even when the yolk sac scar is not. The spiral valve count given for P. africanum by Compagno (1988) was 13, which is slightly higher than that reported here.

Distribution. P. africanum is a mostly inshore shark of temperate waters endemic to the south coast of South Africa, with a preference for rocky reefs, and was verified in the current study as ranging from Granger Bay, Table Bay, Western Cape to just north of East London, Eastern Cape (Fig. 2). Gilchrist (1922) described this species as uncommon in Table Bay, although it was recorded from there in this study.

It is commonly found in shallow water (less than 5 m deep) and the deepest record verified here for this shark was 108 m in St Francis Bay (immediately west of Algoa Bay). The southern most record of this species verified in this study, was caught at a depth of 107 m. Wallace et al. (1984) recorded this animal from 73 m in Algoa Bay.

Clark (1997) reports P. africanum as far north on the west coast as Saldanha Bay (approx 32°58.5’S 17°58’E) and it is possible that this shark may range further northwards along the west coast of South Africa, but probably not into Namibian waters. This shark apparently prefers temperate waters and only one specimen of P. africanum examined in this study occurred north of East London. Gilchrist and Thompson (1916) list P. africanum from Natal waters, however, no precise locality was given. If P. africanum does indeed range this far north, it most likely does so as a rare visitor. Bass et al. (1975) found that P. africanum decreases in abundance moving east through its range, and give the easterly limit of its range as south of Natal. Bass (1986) states that P. africanum is far less abundant in Algoa Bay compared to the Western Cape, and is rarely caught from the shore, but occurs in waters 50 m to 100 m.

Bleeker (1878) listed specimen(s?), by name only, referable to P. africanum collected from “de L’ île Maurice” (Mauritius) in the “Museum de Hambourg”. This museum is no longer in existence and the author could not trace the specimens referred to by Bleeker. However, in the Zoological Museum, Hamburg, a specimen ZMH 10169 with the name Poroderma marleyi exists, with a Mauritius locality, determined by G. Dingerkus (I. Eidus and H. Wilkens, pers. comm.). This specimen was not examined by the author. It is very unlikely that shallow water, predominantly temperate, demersal sharks with habits such as Poroderma would range into tropical waters. Furthermore, such a distribution would necessitate crossing the Mozambique Channel. These records from Mauritius are dubious at best, and it is most likely that these records are erroneous.

Sauvage (1891) describes a 45.7 cm specimen of P. africanum from Madagascar. Again, the occurrence of this animal east of the Mozambique Channel in tropical waters is dubious, and it is likely that the locality recorded for this specimen was erroneous. Compagno (1988) examined a specimen of P. africanum (AMNH 43134) that was recorded from Zaire. Compagno could not confirm this record, which is almost certainly erroneous.

Etymology. The species name refers to the type locality for the species.

Common name. This catshark is most commonly called a pyjama shark, although it is also sometimes called a striped catshark or dogfish. In Afrikaans, this shark is called a luihaai(lazy shark) in reference to its diurnal behaviour due to its nocturnal habit. Other Afrikaans names include bank-haai (reef shark) and streep-kathaai (striped catshark).

Study material. BAH 20010000.1, mature female 880 mm TL, De Monde, Struis Bay, Western Cape, approx. 34"42.8'S 20"07.3'E; BAH 20010000.2, mature male 955 mm TL, De Monde, Struis Bay, Western Cape; BAH 20010000.3, mature male 887 mm TL, De Monde, Struis Bay, Western Cape; BAH 20010000.4, mature female 969 mm TL, De Monde, Struis Bay, Western Cape; BAH 20010000.5, mature male 921 mm TL, De Monde, Struis Bay, Western Cape; BAH 20010000.6, adolescent female 786 mm TL, De Monde, Struis Bay, Western Cape; BAH 20010000.10, mature male 866 mm TL, De Monde, Struis Bay, Western Cape; BAH 20010000.11, mature male 801 mm TL, De Monde, Struis Bay, Western Cape; BAH 20010000.12, mature male 897 mm TL, De Monde, Struis Bay, Western Cape; BAH 20010000.13, adolescent female 802 mm TL, De Monde, Struis Bay, Western Cape; BAH 20010000.24, mature female 910 mm TL, Millers Point, False Bay, Western Cape, approx. 34"14'S 18"28.6'E; BAH 20010000.25, adolescent female 667 mm TL, Millers Point, False Bay, Western Cape; BAH 20010000.26, mature female 785 mm TL, Millers Point, False Bay, Western Cape; BAH 20010000.27, mature female 880 mm TL, Millers Point, False Bay, Western Cape; BAH 20010000.28, adolescent female 756 mm TL, Millers Point, False Bay, Western Cape; BAH 20011119.11, mature male 972 mm TL, Millers Point, False Bay, Western Cape; BAH 20011119.18, juvenile male 337 mm TL, Long Beach, Simonstown, False Bay, Western Cape, approx. 34"11.15'S 18"25.6'E; BAH 20011119.19, juvenile female 447 mm TL, Long Beach, Simonstown, False Bay, Western Cape; BAH 20011120.1, mature male 850 mm TL, False Bay, Western Cape; BAH 20011120.2, mature male 952 mm TL, False Bay, Western Cape; BAH 20011120.3, mature male 862 mm TL, False Bay, Western Cape; BAH 20030107.1, juvenile female 403 mm TL, Jeffreys Bay, Eastern Cape, approx. 34"03.3'S 24"55.5'E; BAH 20030107.2, adolescent female 715 mm TL, Jeffreys Bay, Eastern Cape; LJVC 820927, mature male 725 mm TL, Bushmans River, Kenton on Sea, Eastern Cape, approx. 33"41.7'S 26"39.7'E; LJVC 940927, 3 juvenile males 266 mm, 276 mm, and 298 mm TL, R.V. Africana Cruise 125, A16575 2146-030, 34"26'S 21"31'E; MJS uncat., 2 specimens, juvenile male 416 mm TL, mature female 920 mm TL, Algoa Bay, Eastern Cape, approx. 33"45'S 25"54'E; MJS 860701, juvenile male 550 mm TL, Bird Island, Algoa Bay, Eastern Cape, 33"50.4'S 26"17.2'E; MJS 880626, adolescent female 865 mm TL, Noordhoek, Eastern Cape, approx. 34°02'30"S 25°38'30"E; RUSI 6278, embryonic male 149 mm TL, Buffels Bay, Western Cape, 34"05'S 23"00'E; RUSI 17034, embryonic female 116 mm TL, Cannon Rocks, Eastern Cape, 33"45'S 26"32'E; RUSI 26481, juvenile female 372 mm TL, Algoa Bay, Eastern Cape, 34"01'S 25"47'E; RUSI 26885, juvenile male 251 mm TL, R.V. Africana Cruise 048, A4752 1039-030, 34"15'S 22"04'E; RUSI 41531, juvenile female 348 mm TL, R.V. Africana Cruise 106, A13982, 34"08'S 25"05'E; RUSI 48498, juvenile male 163 mm TL, Plettenberg Bay, Western Cape, 34"04'S 23"25'E; RUSI 55004, embryonic female 169 mm TL, Mossel Bay, Western Cape, 34"22'S 21"52'E; RUSI 55512, embryonic female 110 mm TL, Cefane Beach, Eastern Cape, 32"45'S 28"12'E; SAM 28624, 3 specimens; SAM 28633, juvenile male 516 mm TL, False Bay, Western Cape; SAM 29304, 19 specimens; SAM 32571, 1 specimen.