Holohalaelurus punctatus (Gilchrist 1914)
Brett A. Human, 2006, A taxonomic revision of the catshark genus Holohalaelurus Fowler 1934 (Chondrichthyes: Carcharhiniformes: Scyliorhinidae), with descriptions of two new species., Zootaxa 1315, pp. 1-56: 6-18
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|Holohalaelurus punctatus (Gilchrist 1914)|
(Fig. 2, Table 1)
Halaelurus (Holohalaelurus) punctatus : Fowler, 1934: 235; Fowler, 1941: 42.
Halaelurus punctatus : Fowler, 1935: 361.
Scyliorhinus (Halaelurus) punctatus : Norman, 1939: 10.
Holohalaelurus polystigma : Compagno & Human, 2003: 12.
Type Series and Locality. Neotype, designated herein, RUSI 6128 (previously ORI 2529), mature male 298mm TL, from “Red Cliff off Bazaruto” , Mozambique, in 130-140 fms (~237-256m), May 16, 1969, between 03:45 to 07:00hrs, in very good condition.
Diagnosis. A dwarf species of Holohalaelurus ZBK , the following distinguishes H. punctatus from other Holohalaelurus ZBK sharks: denticles on dorsal midline not enlarged, the only Holohalaelurus ZBK shark not to have enlarged denticles on the dorsal midline; denticles on the dorsal surface of the pectoral fin not enlarged in adults; club-shaped papillae not present on the distal tip of the clasper; buccal papillae in mouth large and prominent on upper and lower surfaces; relatively low vertebral count, 112 total vertebrae in the neotype (mean 106.5); relatively low tooth counts, 45 upper teeth in total in the neotype (mean 45.9), 46 lower teeth in total in the neotype (mean 43.3). Covered in small dark spots on a golden yellow background, with scattered white spots; large white spot above pectoral fin insertion; white spot at the origin of each dorsal fin; faint twin V-shaped markings on both dorsal fins of fresh specimens.
Description. Morphometric and meristic data are given in Table 1. Neotype, mature male 298mm TL (mean of all specimens examined in Table 1, including the neotype, see Study material): body slender and elongate; head compressed, head width 2.35 (2.15) times its height at the posterior margin of the orbit, and head width 1.65 (1.73) times its height at the pectoral fin origin; trunk depressed, trunk width 1.74 (1.46) times its height; abdomen slightly depressed, abdomen width 1.06 (1.19) times its height; tail slightly depressed, tail width 1.17 (1.02) times its height; caudal peduncle compressed, caudal peduncle height 1.80 (1.69) times its width; ventral sensory pores conspicuously black; head long, head length 0.23 (0.23) times the precaudal length; snout short, rounded and coming to a point, preoral length 0.20 (0.23) times the snout to first gill slit distance; mouth long and wide, acutely arched, buccal papillae in mouth large and prominent on upper and lower surfaces, mouth width 2.0 (2.29) times its length; eye slit like, eye length 2.25 (1.95) times its height, distance from snout to the anterior origin of the orbit 0.66 (0.63) times the snout to spiracle length; spiracle length 0.11 (0.22) times the eye length; area around gill slits naked, lacking denticles; distance from snout to first dorsal fin origin 0.68 (0.68) times the distance from the snout to the second dorsal fin origin; no enlarged denticles on the dorsal midline; first dorsal fin length 1.95 (2.05) times its height, length of the base of first dorsal fin 0.97 (0.88) times the length of the base of second dorsal fin; second dorsal fin length 2.19 (2.29) times its height; snout to pectoral origin length 0.54 (0.52) times the snout to pelvic fin origin length; pectoral fin large and winglike, no enlarged denticles on the dorsal surface in adults, pectoral fin length 1.47 (1.54) times its height; height of the pectoral fin 2.35 (2.56) times the height of the pelvic fin; distance from pectoral insertion to pelvic origin 1.14 (0.96) times the distance between the insertion of the second dorsal fin and the caudal fin dorsal origin; pelvic fin long and low, pelvic fin length 3.81 (4.0) times its height, pelvic fin free rear tips variably fused, but never completely fused; claspers elongate without papillae on the distal tips, clasper inner margin length 7.29 (8.14) times their base; snout to anal origin length 3.93 (3.29) times the distance between the anal fin insertion and the origin of the ventral caudal fin; anal fin long and low, anal fin length 3.97 (4.45) times its height; length of anal fin base 1.54 (1.63) times the length of the second dorsal fin base; caudal dorsal margin length 1.53 (1.51) times the interdorsal space, caudal ventral lobe weakly developed. Vertebral counts: 27 (26.8) monospondylous, 51 (49.4) precaudal diplospondylous and 34 (30.2) caudal diplospondylous vertebrae. Dental formula: upper jaw (left) 22 (22.5), symphyseal 0 (1.3), (right) 23 (22.2); lower jaw (left) 21 (19.7), (symphyseal) 4 (2.7), (right) 21 (20.8).
Size and Sexual Maturity. Holohalaelurus punctatus is a dwarf species of Holohalaelurus ZBK (Fig. 1 and Table 1) and reaches a maximum length of at least 326mm TL. Males are immature at 176mm TL, adolescent at 235mm TL, and mature at 298mm TL to 326mm TL, which is very similar to that reported by Bass et al. (1975), although they report maximum size as 34cm. Females are immature at 176mm TL to 227mm TL, and adolescent at 236mm TL based on external examinations, however, if sexual dimorphism is as exaggerated as it is in H. regani , then the maturity of these females may be underestimated.
Colouration. A stunningly patterned shark (Fig. 2), H. punctatus has a background dorsal colouration golden yellow brown to dark brown, covered with many dark brown irregularly shaped spots, infrequently solid and more often paler towards the centre of the spot, always distinct and not fused into stripes or blotches; faint saddles sometimes present on body, usually above branchial region and on the area just posterior to the posterior margin of the pectoral fin; white spots much less frequent than dark spots, randomly scattered over dorsal surface, except for a single white spot at the origin of each dorsal fin, and a large white spot on the lateral surface of the body, posterior to the gill slits and above the pectoral base; spots on pectoral and pelvic fins, although not always seen on preserved animals, spots larger on pectoral fin than on body, but not fused or expanded into blotches or stripes, occasionally a broad dark brown band is seen at the base of each dorsal fin, but no other markings seen on preserved animals. Faint twin V-shaped markings reported on both dorsal fins of fresh specimens, apparently fade with preservation. Ventral colouration is off white to grey-brown or pale mustard, no markings on the underside of fins, although fin webs darker, red-brown, sensory pores on underside of head and trunk black, these faded on some preserved specimens.
Comparison with other species. Holohalaelurus punctatus is differentiated from all other Holohalaelurus ZBK sharks in lacking enlarged denticles on the dorsal midline, whereas all other members of the genus have noticeably enlarged dorsal denticles to varying degrees. Adult H. punctatus do not have enlarged denticles on the dorsal surface of the pectoral fins, unlike adult H. favus and H. regani . The buccal papillae are more noticeable in H. punctatus compared to any other Holohalaelurus ZBK . There is no fusion of the spots into bars and reticulations as there is in H. favus , H. melanostigma or H. regani . A white spot present posterior to the gill slits above the pectoral fin bases is also present in H. grennian , and a white spot at the origin of each dorsal fin is unique to H. punctatus . Holohalaelurus punctatus grows to a larger size than H. grennian , but is smaller than all other congeners. Holohalaelurus punctatus is closest to H. grennian in overall morphology and colouration.
Remarks. There are three main issues that contribute to the taxonomic confusion associated with H. punctatus . Firstly, the type locality of the holotype; secondly, the loss of the holotype; and thirdly, the Holohalaelurus ZBK species complex that had been referred to in the literature in the kwaZulu-Natal/ southern Mozambique region.
Gilchrist (1914) gave the type locality as off Cape Point with no further details and it is likely that the holotype actually came from kwaZulu-Natal (possibly Cape St. Lucia). At the time, Gilchrist was conducting marine surveys aboard the S.S. Pickle. Upon inspection of the log of the S.S. Pickle during that period, it is apparent that the vessel was travelling continuously between Cape and Natal waters, which may have led to the error. Furthermore, the holotype was described from a preserved specimen (Gilchrist, 1922), which may support the notion that the locality data accompanying the specimen was erroneous.
Gilchrist (1914) referred to a specimen 245mm TL in his description of S. punctatus ZBK and the accompanying illustration of S. punctatus ZBK would suggest that it was a female. This specimen would classify as the holotype and may have been placed in the South African Museum but not catalogued, as other species described in the same account have SAM catalogue numbers that were not referred to in the text ( Dentex albus ZBK SAM 11701, and Selene gibbiceps ZBK SAM 13725). However, Barnard (1925) refers to the type of H. punctatus , “Type of punctatus ZBK in coll. Gilchrist”. There is no reference to a scyliorhinid shark collected by Gilchrist during that period in the South African Museum catalogue. The last reference in the literature to this specimen was by Norman (1939: 10), who mentions a 245mm TL type specimen, gives limited morphometric proportions, illustrated it (Norman, 1939: Fig. 2B), and may have used it as comparative material for describing H. melanostigma . Eschmeyer (1998) reports no types known for H. punctatus . It seems that types for several taxa were lost (most probably discarded) when Gilchrist left the museum due to conflicts with the administration (Compagno, 1999). For example, the holotypes for Apristurus microps (Gilchrist, 1922) and A. saldanha (Barnard, 1925) seem to have been misplaced during the same period as the loss of the H. punctatus holotype (L.J.V. Compagno, pers. comm.). Therefore, the author considers the holotype of H. punctatus to be lost.
Species reported in the literature from the kwaZulu-Natal/ southern Mozambique region include H. punctatus , H. polystigma , and two forms of H. regani (i.e. the “Cape” and the “Natal” forms). The original descriptions of these species provide only limited details of each, which are insufficient to accurately distinguish between the nominal species. The loss of the H. punctatus holotype, the ambiguity and the juvenile nature of the syntypes of H. regani (see under remarks for H. regani ), the presence of an undescribed taxon (herein described as H. favus sp. nov.), and the putative taxon H. polystigma , obscured the true identity of H. punctatus . The nomenclatural status of H. punctatus could well be confused with either H. polystigma or H. favus .
Due to the taxonomic confusion surrounding Holohalaelurus ZBK sharks, especially for H. punctatus as described above, the designation of a neotype is warranted in accordance with Articles 75.1 and 75.3 of the International Commission for Zoological Nomenclature (ICZN, 1999). The designation of a neotype from Red Cliffs, Bazaruto Island, Mozambique results in the type locality changing to Red Cliffs, Bazaruto Island, Mozambique in accordance with Article 76.3 (ICZN, 1999). The ambiguity of the original type locality, and the (previous) abundance of this species in the region of the current type locality, will serve to stabilise the taxonomy of this species.
The data accompanying the neotype gives the locality of this specimen as Red Cliffs, Mozambique, without any further information. Examination of the original ORI data sheet for this specimen gives the locality as “Red Cliffs off Bazaruto”, presumably meaning Bazaruto Island, Mozambique, although no coordinates were given. The depth given, however, corresponds to the depth of the trawling grounds in that area (R. van der Elst, pers. comm.).
The morphometric and meristic data presented here (Table 1) agrees with that of Bass et al. (1975), except that their average vertebral count was higher than that given here, and is probably due to the inclusion of small specimens here, causing caudal vertebral counts to be underestimated. Bass et al. (1975) describe the dentition of H. punctatus and note that there is strong sexual heterodonty in this species. Bass (1973) showed that H. punctatus displays an enormous amount of ontogenetic allometry and sexual dimorphism across a number of measurements, although H. punctatus is not as extreme in its allometry or dimorphism as H. regani .
Bass et al. (1975) describe and illustrate H. punctatus as having twin V-shaped markings on the dorsal fins. The author has not observed any markings on the dorsal fins of preserved H. punctatus examined in this study, except for a broad band found on the dorsal fin bases on some specimens (Figs. 2-3). However, specimens illustrated in the ORI data sheets for this species, which correspond to specimens examined by the author, confirm that these markings were present and appear to fade once preserved. Comments on the data sheets with regards to these V-shaped markings indicate that they are rarely bold, and are most often described as being indistinct. There is occasionally present a dark brown band on the dorsal fins. This band is relatively broad and occurs very near the base of the dorsal fins. This band differs from that seen in H. grennian sp. nov. in that the band in the latter species occurs approximately half way along the posterior margin of the dorsal fins, is much thinner, appearing as a streak, and is bordered by pale yellow (Figs. 14 and 15), whereas the band in H. punctatus is not bordered by a paler colour.
Compagno (1988) gives the locality of RUSI 6128 (neotype designated herein) from off of Kenya in the body of his text, however this is incorrect. Compagno (1988) referred to this specimen in respect to a recently collected “regani-like” shark from east Africa, however the size reported by Compagno (391mm TL) is clearly not this specimen, which is 298mm TL. It may be that the specimen that Compagno is referring to is actually H. melanostigma RUSI 14114, although this specimen was measured at 384mm TL in the current study, but is the only Holohalaelurus ZBK shark collected from Kenya that fits this description for that time frame. Compagno cites RUSI 6128 twice in his study material, once for the “regani-like” shark, and also, correctly as a specimen of H. punctatus from Red Cliffs, Mozambique (304mm TL).
The only synonym of H. punctatus is H. polystigma (Regan 1921) . Holohalaelurus polystigma was originally described as Scyliorhinus (Halaelurus) polystigma ZBK , and the holotype (BMNH 19220.127.116.11), a mature male recorded as 320mm TL (measured as 316mm TL in the current study), was collected by Mr H.W. Bell Marley and Mr R. Robinson in 120 to 130 fathoms (approx. 220 to 240m) 15 to 22 miles (24 to 35km) off Umvoti River, kwaZulu-Natal, South Africa. Given the water depth and distance from the Umvoti River, the approximate coordinates for this position are 29°30’S 31°45’E. The holotype of this species is in excellent condition (Fig. 3). It seems that Regan did not examine the holotype, or any specimens referable to H. punctatus , lists no comparative material, and only notes that S. polystigma ZBK is related to S. buergeri Mueller & Henle (= Halaelurus buergeri ), in his description of H. polystigma .
Gilchrist (1922) commented that H. punctatus “… does not seem to differ from Regan’s S. polystigma ZBK …” and synonymised H. polystigma with H. punctatus (as Scylliorhinus punctatus ZBK ), although it is not clear if he ever examined the holotype of H. polystigma . Most authors have since considered H. polystigma a synonym of H. punctatus , including Barnard (1925), Fowler (1935, 1941), Smith (1949), Bass et al. (1975), Springer (1979, who only examined the holotype of H. polystigma and featured a photograph of the underside of the head of that specimen), and Compagno (1984b, 1988). The author agrees with synonymising H. polystigma with H. punctatus , as there are no characters that distinguish these two taxa, as determined by this study.
The conservation status of this species is of concern because Bass et al. (1975) and Bass (1986) describe this species as being a common catch in bottom trawls in Natal and southern Mozambique, and yet, to the authors knowledge, not a single specimen has been collected from this area since 1972, despite recent biodiversity trawl surveys in that region as part of the coelacanth ( Latimeria chalumnae ZBK ) project in progress in the region (P. Heemstra, pers. comm.). The ORI data sheets for this species confirm that those specimens were collected between 1964 and 1972, and were apparently abundant, particularly off Mozambique in May 1969, and off Durban in June 1971. The only specimens of this species that have been collected since this date have been those from Madagascar in the late 1980’s and early 1990’s. Holohalaelurus ZBK sharks from the kwaZulu-Natal and southern Mozambique region are still present in commercial fisheries landings, but apparently only rarely (N. Kistnasamy, pers. comm.). It is not known whether the reduced catch is due to fisheries pressure, habitat loss, pollution, or an as yet unidentified threat.
Distribution. Holohalaelurus punctatus occurs in the southern part of its range from off Durban, South Africa, north to at least Bazaruto Island, Mozambique, along continental Africa, and eastwards to Madagascar, where it is found to occur around the entire island (Fig. 4). Holohalaelurus punctatus is the only Holohalaelurus ZBK that is known to occur east of the Mozambique channel and beyond continental Africa.
The type locality for this species was originally “off Cape Point” with the assumption that it was Cape Point, Western Cape, South Africa. Of the specimens identified as being H. punctatus in the current study, all were collected from kwaZulu-Natal, southern Mozambique, or Madagascar. Although Gilchrist (1922) reconfirms the locality “Cape Point”, inferring that it is Western Cape, and notes the rarity of its occurrence there, Gilchrist also gives additional distribution records of H. punctatus from S.S. Pickle stations 104 & 106, both of which are off Durban. It is likely that the original data accompanying the holotype may have been erroneous and the locality may have been off Cape St. Lucia.
If H. punctatus occurs in southern waters, it does so only as a rare visitor, as confirmed by the study of Compagno et al. (1991), which did not collect a single specimen referable to H. punctatus despite intensive demersal trawling and collection of thousands of H. regani . Interestingly, Smith (1949) describes this species as rare, and may be a reference to its occurrence in Cape waters, since it was apparently not uncommon off kwaZulu-Natal at the time, although he lists its distribution as “Cape to Natal”. Therefore, this species can be considered as endemic to the subtropical and tropical waters of the southwestern Indian Ocean.
Séret (1987) was the first to report Holohalaelurus ZBK from Madagascar, and listed H. punctatus as occurring there, however may not have realised that this was a range extension for the species. Although catalogue numbers were not supplied, the specimens referred to by Séret (1987) are the MNHN specimens that the author has examined photographs of (supplied by R. Ksas), and all are readily identifiable as H. punctatus . Holohalaelurus punctatus is the only species of Holohalaelurus ZBK that is known to occur beyond continental Africa.
Bass et al. (1975) have a reference to H. punctatus from Lampe (1914) recording this species from Mauritius. Lampe (1914) does indeed describe a specimen, var. punctata var. nov. from Mauritius, however this is under his account of Scyllium africanum and is apparently a variant of Poroderma pantherinum which he synonymised with P. africanum (Human, 2006), and therefore is not a reference to H. punctatus . Furthermore, Lampes’ specimen was 70cm long, making it highly unlikely to be a Holohalaelurus ZBK shark. Holohalaelurus punctatus has not been verifiably recorded from Mauritius, although it’s presence there is not unlikely, given that its distribution surrounds Madagascar.
Etymology. Gilchrist (1914) did not provide the derivation of the species name in his account, however it is most likely derived from the Latin, punctum, meaning small hole, dot or spot, and is reference to the many small spots covering the dorsal surface of this species.
Common name. Gilchrist did not give a common name for H. punctatus in his description of it (Gilchrist, 1914). It is here given the name white-spotted Izak, in reference to the presence of scattered white spots on the dorsal surface. Also, characteristic of this species are the single white spots present at the origin of each of the dorsal fins. Although white spots are present in other Holohalaelurus ZBK species, they are not as prevalent as they are in H. punctatus .
This shark was given the common name small-spotted Izak for the recent chondrichthyan species checklist for subequatorial Africa (Compagno & Human, 2003), and the common name white-spotted Izak was given to H. polystigma . At that time, the current revision was in progress and it was thought that H. polystigma was a distinct species, however it has since been resolved that H. polystigma is a synonym of H. punctatus .
Other common names previously used for this species include spotted dogfish (Gilchrist, 1922), punctate dogfish (Barnard, 1925), spotted catshark (Bass et al., 1975; Bass 1986), and African spotted catshark (Compagno, 1984b; Compagno, 1988; Compagno et al., 1989; Compagno & Smale, 1989; Compagno et al., 1991, 2005), however there are many African spotted catsharks. White-spotted Izak was chosen as a more descript common name and has since been used by Compagno et al. (2005).
Study material. BMNH 1918.104.22.168, holotype of H. polystigma (Regan 1921) , mature male 316mm TL, 15-20 miles off Umvoti River , kwaZulu-Natal, South Africa, approx. 29°30'S 31°45'EGoogleMaps ; MNHN 1987-1291, male 348mm TL, Tulear , Madagascar, approx. 23°20'S 43°31'EGoogleMaps ; MNHN 1987-1292, male 321mm TL, Tulear , MadagascarGoogleMaps ; MNHN 1987-1293, female 277mm TL, Tulear , MadagascarGoogleMaps ; MNHN 1987-1294, male 335mm TL, Tulear , MadagascarGoogleMaps ; MNHN 1988-0356, male 355mm TL, Tulear , MadagascarGoogleMaps ; MNHN 1991-0410, female 272mm TL, Madagascar , 18°54'S 48°55'EGoogleMaps ; MNHN 1991-0411, female 220mm TL, Madagascar , 25°29'S 46°46'EGoogleMaps ; MNHN 1991-0412, male, 330mm TL, Madagascar , 23°36'S 43°31'EGoogleMaps ; RUSI 6128, designated neotype of H. punctatus (Gilchrist 1914) , see under Type Series and Locality for details; RUSI 6129, previously ORI 2548, adolescent male 235mm TL, Red Cliffs, Bazaruto Island , Mozambique ; RUSI 6131, previously ORI 2581, immature female 181mm TL, Bazaruto Island , Mozambique, 21°40'S 35°30'EGoogleMaps ; RUSI 6132, previously ORI 2577, immature female 227mm TL, Maputo Bay , Mozambique, 25°35'S 33°30'EGoogleMaps ; RUSI 6133, previously ORI 2585, immature female 196mm TL, Bazaruto Island , MozambiqueGoogleMaps ; RUSI 6134, previously ORI 2721, immature male 176mm TL, Durban , kwaZulu-Natal, South Africa, 29°51'S 31°00'EGoogleMaps ; RUSI 6136, previously ORI 2553, adolescent female 236mm TL, Maputo Bay , MozambiqueGoogleMaps ; RUSI 6137, previously ORI 2554, immature female 218mm TL, Maputo Bay , MozambiqueGoogleMaps ; RUSI 40829, 4 specimens, all mature males 303mm TL, 310mm TL, 323mm TL, and 326mm TL .
To the authors knowledge, these specimens are all of the known specimens referrable to this species.
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