Redescription of Squalus acutipinnis Regan, 1908, a Valid Species of Spiny Dogfish from Southern Africa (Chondrichthyes: Squaliformes: Squalidae)
Author
Sarah T. de F. Viana
Author
Marcelo R. de Carvalho
text
Copeia
2016
104
2
539
553
journal article
10.1643/Ci-14-217
99f7484f-0164-421a-998f-bd11e5f517ce
269591
Squalus acutipinnis
Regan,
1908
Stompneus-penhaai (Afrikaans); Bluntnose spiny dogfish (English) Figures
1–9
;
Tables
1–2
Squalus acutipinnis
Regan
1908
a
:
241, 248
, pl. XXXVII (original description, illustrated;
type
locality: Kwazulu-Natal,
South Africa
[not NE of Bird Island as stated on p.
241
];
40
ftm/
73.152 m
;
lectotype
:
BMNH
1905.6
.
8.8
[see below]).–
Regan,
1908
b
:45
, 47 (cited;
South Africa
,
Mauritius
).–
Regan,
1921
:
412
(listed; Kwazulu-Natal,
South Africa
).–
Krefft,
1968
(in part):34, 51–
54
, pl. III A (cited, description, designation of
lectotype
;
South Africa
).–
Merrett,
1973
:
94, 104, 108, 109
(cited;
South Africa
).–
Kondyurin and Myagkov,
1979
(revision,
South Africa
[not seen, cited in
Myagkov and Kondyurin,
1986
]).–
Cadenat and Blache,
1981
:47
, 51,
52
, fig.
31
f–g (cited;
South Africa
).–
Myagkov and Kondyurin,
1986
:
8
–10, 15 (description; Southern Africa).–
Last et al.,
2007
:
11
(cited; Southwest Indian Ocean).–
Ebert et al.,
2010
:22
, 23 (cited; Southern Africa).–
Ebert and Stehmann,
2013
(in part):
66
(cited as possibly valid; Southern Africa).
Squalus fernandinus
not Molina,
1782
.—
Garman
,
1913
:
195– 196
(synonymy, description).–
Bigelow and Schroeder,
1948
:
480
(cited,
South Africa
).–
Bigelow and Schroeder,
1957
:32
, 35 (cited,
South Africa
).–
Smith,
1961
:59
, 61 (brief account,
South Africa
).
Squalus megalops
(not MacLeay,
1881
).—
Bass et al.,
1976
(in part):11, 9–13, 16–18, 60; fig.
11
; pl.
3
(description, illustrated; Southern Africa).–
Compagno,
1984
(in part):
118, 119
(description, illustrated;
South Africa
).–
Bass et al.,
1986
(in part):61, 62, fig.
5.26
(description; Southern Africa).–
Parin,
1988
:
49
(cited; Southeastern Atlantic Ocean).–
Muñoz-Chápuli and Ramos,
1989
:6, 11, 18, 19 (diagnosis, illustrated, Eastern Atlantic).–
Compagno et al.,
1989
(in part):
22
(account, illustrated).–
Compagno and Niem,
1999
(in part):
1230
(cited;
South Africa
to
Mozambique
).–
Ebert et al.,
2013
(in part):
91
(general account on
S. megalops
).
Squalus
cf.
megalops
.—
Naylor et al.,
2012
a
(in part):
58, 148
, fig.
42
(cited, molecular systematic analysis;
South Africa
, Indian Ocean).–
Naylor et al.,
2012
b
(in part):fig.
2.7
(molecular systematic analysis;
South Africa
).
Lectotype
.—
BMNH
1905.6
.
8.8
,
juvenile
female
,
578 mm
TL,
Western Indian Ocean
,
South Africa
,
Kwazulu-Natal
, donated by Dr. E. Warren. Designated by
Krefft (
1968
)
.
Paralectotypes
.—
(
3
specimens
)
BMNH
1859.5
.
7.68
(not
Squalus acutipinnis
), neonate female,
190 mm
TL, Southeastern Atlantic Ocean,
South Africa
, Cape of Good Hope, donated by Sir Andrew Smith;
BMNH
1881.3
.
11.2
, adult female,
852 mm
TL, stuffed specimen, Western Indian Ocean,
Mauritius
, donated by M.
De
Robillard;
BMNH
1900.
11.
6.14
(not
Squalus acutipinnis
), adult female,
565 mm
TL, Southeastern Atlantic Ocean,
South Africa
, Table Bay, donated by Dr. J. D. F. Gilchrist.
Fig. 1. Lectotype of
Squalus acutipinnis
, BMNH 1905.6.8.8, adult female, 578 mm TL from Kwazulu-Natal, South Africa: (A) lateral view; (B) ventral view; (C) first dorsal fin; (D) second dorsal fin.
Non-type material.—
(
29
specimens
)
SAIAB
7829
, adult female,
575 mm
TL,
South Africa
, Port Elizabeth,
33.96
°S
,
25.60
°E
;
SAIAB
10443, 3 neonate females,
200 mm
TL each, neonate male,
200 mm
TL, adult male,
410 mm
TL,
South Africa
, Cape Town,
33.91
°S
,
18.41
°E
;
SAIAB
19863
, adult female,
570 mm
TL,
South Africa
, Port Alfred,
34.26
°S
,
27.58
°E
;
SAIAB
21933
, juvenile female,
252 mm
TL,
South Africa
, off Gansbaai,
35.03
°S
,
19.43
°E
;
SAIAB
25360
, adult female,
530 mm
TL,
South Africa
, Algoa Bay,
34
.0
3
°S,
25.70
°E
;
SAIAB
25361
, juvenile female,
460 mm
TL,
South Africa
, Algoa Bay,
34.03
°S
,
25.70
°E
;
SAIAB
25369
, juvenile female,
375 mm
TL, adult female,
450 mm
TL,
South Africa
, Algoa Bay,
34.03
°S
,
25.70
°E
;
SAIAB
25390
, juvenile female,
460 mm
TL,
South Africa
, Algoa Bay,
34.03
°S
,
25.70
°E
;
SAIAB
25394
, adult female,
525 mm
TL,
South Africa
, Algoa Bay,
34.03
°S
,
25.70
°E
;
SAIAB
26639
, adult female,
485 mm
TL, unknown locality;
SAIAB
34576
, adult female,
550 mm
TL,
South Africa
, Bushmans River Mouth,
33.68
°S
,
26.66
°E
;
SAM
12986
, neonate female,
185 mm
TL,
South Africa
, unknown precise locality;
SAM
12996
, neonate male,
205 mm
TL,
2
neonate females,
202, 205 mm
TL,
South Africa
, St. Francis Bay,
34.06
°S
,
25.13
°E
;
SAM
28638
,
2 juvenile
females,
365, 375 mm
TL,
South Africa
, False Bay,
34.18
°S
,
18.61
°E
;
SAM
32550
, adult female,
695 mm
TL, unspecified locality,
South Africa
, Eastern Cape,
34.44
°S
,
26.01
°E
;
SAM
32894
, neonate female,
273 mm
TL,
3
juvenile
males,
240, 310, 318 mm
TL,
South Africa
, off Mossel Bay,
34.56
°S
,
22.53
°E
;
SAM
34217
, juvenile male,
395 mm
TL,
South Africa
, Eastern Cape, unspecified locality,
34.13
°S
,
26.36
°E
;
ZMB
19151
, adult female,
675 mm
TL,
South Africa
, Simonstown.
Diagnosis.—
A species of
Squalus
mostly from the Western Indian Ocean diagnosed by the following combination of characters: snout rounded and short (preorbital snout length
6.3
% for
lectotype
,
6.5–7.1
% TL for non-type material), prenarial snout length
0.8
(
0.9
–1.0) times inner nostril-labial furrow space; first dorsal fin upright, triangular in shape and low (
8.2
%, 8.0–
9.3
% TL); pectoral fins markedly broad with posterior margin conspicuously greater than trunk height when adpressed on body; and caudal fin with narrow dorsal lobe and continuous caudal fork between lobes.
Squalus acutipinnis
can be distinguished from all species of the
S. megalops-cubensis
group (except from
S. megalops
,
S. brevirostris
,
and
S. crassispinus
) by fewer total (
108, 107
–
111
[mode
109
,
n
¼
10
] vs.
113–125
), precaudal (81, 81–
83
[mode
82
,
n
¼
10
] vs.
84–96
), and monospondylous vertebrae (41, 37–
42
[mode
40–41
,
n
¼
10
] vs.
41–49
).
Squalus acutipinnis
differs from
S. megalops
from Southern
Australia
by having a rounded snout (vs. pointed snout), L-shaped free rear tips of pectoral fins and pectoral fins not lobe-like (vs. evidently rounded and lobe-like pectoral fins), triangular first dorsal fin (vs. rounded first dorsal fin at tip), pectoral fins transcending trunk height when adpressed on body (vs. pectoral fins, never reaching trunk height), shorter prespiracular length (
11.6
%,
7.7–12.1
% TL vs.
13.5
%,
11.6–13.4
% TL), more elongated first dorsal spine (
3.5–4.3
% TL vs.
1.8–3.6
% TL), dermal denticles broad at crown with length equal to width (vs. dermal denticles slender at crown with length much greater than width), and margins of pectoral and caudal fins white but not uniform (vs. evident uniform white margins).
Squalus acutipinnis
further differs from
S. brevirostris
from
Japan
by having pectoral fins with L-shaped free rear tips and not lobe-like, and with straight posterior margin (vs. pectoral fins triangular and with pointed free rear tips, lobe-like and with strongly concave posterior margin), length of pectoralfin anterior margin
1.8
(
1.5–1.9
) times greater than length of its inner margin (vs. length of pectoral-fin anterior margin
1.4
,
1.2–1.5
times greater than its inner margin length), and length of first dorsal-fin posterior margin relatively greater
9.6
%,
8.8–10.3
% TL (vs.
7.7
%,
8.3–8.8
% TL). The Southern African species is also clearly distinct from
S. crassispinus
by narrower first and second dorsal spines (first dorsal spine base width
0.6
%,
0.6–0.9
% of TL vs.
1.3
%,
1.2–1.3
% of TL; second dorsal spine base width
0.6
%,
0.7
–1.0% of TL vs.
1.5
%,
1.3– 1.4
% of TL).
Description.—
Measurements and meristic data are summarized in
Tables
1
and
2
. Single values are for
lectotype
, while ranges represent all non-type specimens from which data were taken.
External morphology.—
Body fusiform (
Fig.
1
), arched from posterior margin of eye to vertical through pelvic-fin origin, and very deep at trunk with height 12.0% TL in
lectotype
(
9.2–12.7
% TL for non-type specimens). Head very small, its length
23.1
% (
21.4–24.3
%) TL, depressed anteriorly; head width
1.2
(
1.1–1.4
) times trunk width, and
1.7
(
1.4–1.7
) times abdomen width. Snout short 4.0% (
3.9–4.4
%) TL, obtuse, and rounded at tip; nasal apertures oblique and located laterally with strongly bilobed anterior margin of nostrils; prenarial length
0.8
(
0.9
–1.0) times eye length and one-half preoral length; prenarial length
0.8
(
0.9
–1.0) times distance between nostril and upper labial furrow. Eyes large (
5.1
%,
4.3–5.1
% TL) and horizontally oval, with concave anterior margin and acute posterior margin; eye length
3.5
(2.0–
2.8
) times its height, positioned nearer to snout tip than to first gill slit. Prespiracular length about one-half prepectoral length; spiracles half-moon shaped, small (
1.5
%,
1.2– 2.2
% TL), located above and posterior to posterior eye margin. Fifth gill slit height
1.5
(1.0–
1.4
) times first gill slit height.
Mouth highly arched and broad, its width
8.5
% (
7.7
–9.0%) TL and
2.2
(
1.9–2.2
) times distance between nostrils; upper labial furrow elongated
2.8
% (
2.5–2.9
%) TL and slim. Unicuspid teeth similar in both jaws, labial-lingually flattened and alternate, broad at crown; teeth broader in lower jaw than in upper jaw; cusp robust and slightly elongated, diagonal and upwardly directed; mesial cutting edge concave; distal heel markedly rounded; slender mesial heel; apron short in upper teeth and more elongated in lower teeth;
lectotype
with three series of functional teeth in upper jaw and two series in lower jaw; tooth row formula
13
/
11
(
Fig.
2
;
Table
2
).
Pre-first dorsal length
1.4
(
1.3–1.5
) times prepectoral length. Triangular first dorsal fin with convex anterior margin, straight posterior margin, slightly slender at apex, very low with height
8.2
% (8.0–
9.3
%) TL, corresponding to
1.5
(
1.4–1.5
) times its inner margin length; wide at its base with base length
8.3
% (
7.5–8.5
%) TL; first dorsal fin length
1.2
(
1.1–1.3
) times second dorsal fin length. First dorsal spine short (
1.9
%,
3.5–4.3
% TL), not reaching fin apex. Interdorsal space 1.0 (1.0–
1.3
) times prepectoral length, and
1.9
(
1.7–2.4
) times dorsal-caudal distance. Second dorsal fin also low, its height
6.1
% (
5.1–6.7
%) TL, corresponding to
1.2
(1.0–
1.4
) times its inner margin length; wide at its base (
6.5
%,
5.7– 7.8
% TL base length); second dorsal fin with convex anterior margin and concave posterior margin, fairly falcate. Second dorsal spine slender and elongate (
3.8
%,
4.5–6.3
% TL), not reaching fin apex; second dorsal spine length 2.0 (
1.1–1.6
) times first dorsal spine length.
Pectoral fins conspicuously broad with convex anterior margin, forming an acute angle with its posterior margin; inner margin convex; posterior margin somewhat straight; both apex and free rear tip rounded, although the latter Lshaped and not lobe-like; pectoral fin apex slightly transcending its free rear tip; length of pectoral-fin anterior margin
1.8
(
1.5–1.9
) times greater than its inner margin length; length of pectoral-fin posterior margin conspicuously transcending trunk height when adpressed on body; length of pectoral-fin posterior margin
1.1
(1.0–
1.4
) times trunk height. Pectoral-pelvic distance
0.7
(
0.7–0.9
) times pelviccaudal distance; pre-pelvic length
1.5
(
1.3–1.6
) times distance between dorsal fins; pelvic fin located at mid-distance between first and second dorsal fins in
lectotype
, but in non-type specimens pelvic fin slightly nearer to second dorsal fin than to first dorsal.
Pelvic fins pentagonal with slightly convex anterior and posterior margins, and free rear tips pointed and triangular; pelvic fin length
10.8
% (
9.8–11.6
%) TL; pelvic inner margin length
5.1
% (
4.2–6.4
%) TL. Clasper in adult males slightly transcending pelvic fin free rear tips, with clasper outer length
1.8
% TL; siphon prominent, short, and located ventrally from the posterior half of the basipterygium to intermediate cartilages of pelvic fins; clasper groove longitudinal, positioned dorsally; apopyle with broad aperture, anteriorly situated in clasper groove; hypopyle with narrow aperture, posteriorly in clasper groove and anterior to rhipidion; rhipidion large, flap-like with its free edge laterally positioned, internally supported by dorsal terminal
2
cartilage, and located at posterior end of clasper (
Fig.
3
).
Caudal peduncle with evident lateral keels, originating behind insertion of second dorsal fin; upper and lower precaudal furrows well developed; caudal fin somewhat rectangular with elongated upper caudal lobe (
20.7
%,
19.7– 22.8
% TL), slightly slender at tip dorsal to vertebral column; upper caudal lobe length
0.9
(
0.8–1.1
) times head length, and 2.0 (
1.8
–2.0) times lower caudal lobe length; short lower caudal lobe (
10.5
%,
10.3
–12.0% TL) with straight preventral margin; very discrete caudal fork between lobes, its width
7.2
% (
6.9–7.5
%) TL.
Fig. 3. External morphology of clasper of
Squalus acutipinnis
(SAIAB 10443, adult male, 410 mm TL from Cape Town, South Africa) in dorsal view. Abbreviations: accessory terminal cartilage (T3); apopyle (AP); clasper groove (CG); hypopyle (HP); pelvic fin (P2); rhipidion (RH).
Dermal denticles.—
Denticles lanceolate and unicuspid (
Fig.
4
), somewhat broad at crown; denticles close together but not imbricated; denticle length slightly greater than width; median ridge elongated, extending far anteriorly from crown base; lateral ridges shorter than median ridge, asymmetrical with irregular lengths; both median and lateral ridges bifurcate distally. Juveniles differ from adults by having somewhat more slender denticles, very sparsely grouped, relatively far from each other; median ridge prominent, not bifurcated; lateral expansions inconspicuous.
Coloration.—
Body brownish dorsally (
Figs. 8
,
9
) and pale laterally from dorsal to pelvic fins to just anterior to upper caudal furrow, and extending ventrally. Dorsal fins brown, whitish at fin base, with posterior margin discretely white although not extending to apex on first dorsal fin; dorsal-fin spines light brown and whitish at tips. Pectoral fins brown, pale at base, with posterior margins white but not uniform. Pelvic fins light gray, pale dorsally and ventrally at base, and whitish on inner and posterior margins. Caudal fin predominantly dark brown with post-ventral margins not uniformly white, and slightly broad white apex on ventral lobe.
Clasper skeletal morphology.—
Intermediate segment single (
Fig.
5
), barrel-shaped and small, connecting pelvic fin basipterygium to axial cartilage of clasper; beta cartilage single, cylindrical and slender, located dorsal to intermediate segment; short and sinuous axial cartilage; end-style slender with constricted distal extremity; dorsal marginal cartilage elongated, sinuous laterally, dorsal to axial cartilage; ventral marginal cartilage broad distally, concave on inner side, forming a folded plate at contact with accessory terminal cartilage (or spur); accessory terminal cartilage exposed externally, slender, thorn-like, somewhat elongated, with evident lateral furrows on each side, and partially attached to ventral terminal cartilage; dorsal terminal cartilage short and hook-like, slightly concave at tip, located distally to dorsal marginal cartilage; dorsal terminal
2
cartilage leaf-like, sharp on lateral edge, attached medially to dorsal terminal cartilage and anteriorly to dorsal marginal cartilage; ventral terminal cartilage somewhat spoon-like with rounded posterior tip.
South Africa; (B) BMNH 1900.11.6.14 (paralectotype), female, 565 mm TL from Table Bay, South Africa; (C)
Squalus megalops
, AMS I 16255- 0 0 1 (holotype), female, 550 mm TL from Port Jackson, Australia; (D)
Squalus brevirostris
, KAUM-I 377, male, 377 mm TL from Kagoshima, Japan.
Fig. 2. Detail of the upper and lower teeth. (A)
Squalus acutipinnis
, BMNH 1905.6.8.8 (lectotype), female, 578 mm TL from Kwazulu-Natal,
Fig. 4. Dermal denticles of
Squalus acutipinnis
. (A) BMNH 1905.6.8.8, female, 578 mm TL (photograph of lectotype). Scanning electron microscopy (SEM): (B) SAIAB 34576, female, 550 mm TL from Kwazulu- Natal, South Africa; (C) SAM 28638, female, 365 mm TL from False Bay, South Africa; (D) SAM 32894, male, 310 mm TL from Mossel Bay, South Africa. Scale bars: 100 lm. See Last et al. (2007) for comparisons with congeners.
Fig. 5. Radiograph showing internal components of clasper.
Squalus acutipinnis
, SAIAB 10443, male, 410 mm TL. Abbreviations: accessory terminal cartilage (T3); axial cartilage (AX); beta cartilage (b); dorsal marginal cartilage (RD); dorsal terminal cartilage (TD); intermediate segment (b1); ventral marginal cartilage (RV); ventral terminal cartilage (TV).
Vertebral counts.—
Precaudal vertebrae
81
for
lectotype
(
81–83
[mode
82
] for non-type specimens;
Table
2
); caudal vertebrae
27
(
25–29
[mode
27–28
]); total vertebrae
108
(
107–111
[mode
109
]); monospondylous vertebrae
41
(
37–42
[mode
40–41
]); diplospondylous vertebrae
67
(
66–71
[mode
68–71
]).
Geographic distribution.—
Squalus acutipinnis
is originally described from Kwazulu-Natal,
South Africa
, and
Mauritius
(
Fig.
6
). It is more common in the Western Indian Ocean, frequently occurring from Kwazulu-Natal to Algoa Bay in the Eastern Cape (
South Africa
). There are few records from the Atlantic side of
South Africa
but without occurrences to the north-northwest of Cape Town.
⊣
Fig. 6. Map of Southern Africa, showing the distribution of
Squalus acutipinnis
. Lectotype (yellow star), paralectotypes (yellow triangle), non-type specimens (yellow dots).
Fig. 7. Paralectotype of
Squalus acutipinnis
, BMNH 1900.11.6.14, adult female, 565 mm TL from Table Bay, South Africa: (A) lateral view; (B) ventral view; (C) first dorsal fin; (D) second dorsal fin.
Etymology.—
The epithet
acutipinnis
is from
acutus
(¼acute) and
pinna
(¼fin) in Latin, and probably concerns to the acute angle between anterior and posterior margins of the pectoral fin, which was used to characterize this species (etymology not provided in original description).
Remarks.—
Squalus acutipinnis
was first described by
Regan (
1908
a)
based on four specimens from different localities in the Eastern Atlantic and Western Indian Oceans surrounding
South Africa
. All specimens were mentioned in the original description and again in
Regan (
1908
b)
, in which he formally stated that the
syntypes
were deposited in the Natural History Museum in London. Later,
Krefft (
1968
)
designated a
lectotype
for
S. acutipinnis
that corresponds to the specimen figured in the original description and to specific information provided by
Regan (
1908
a)
.
Many morphological characters provided by
Regan (
1908
a)
are congruent with our observations; for example, the short snout, large pectoral fins, and caudal fin with continuous caudal fork between upper and lower postventral margins, as well as some proportional dimensions (e.g., pectoral fin length and its distance to the fifth gill slit). However, some supposedly diagnostic characters of the species, such as prenarial length, inner nostril to labial furrow space, and length and height of first dorsal fin, are not congruent among all
type
specimens of
S. acutipinnis
. This discrepancy is explained by the heterogeneous nature of the
type
series of
S. acutipinnis
(see discussion below). The present redescription is based on the
lectotype
and new (non-type) material from
South Africa
.
Fig. 8. Lateral view of (A)
Squalus acutipinnis
, SAIAB 19863, female, 570 mm TL from Port Alfred, South Africa; (B)
Squalus megalops
, AMS I 45658- 0 0 1, female, 625 mm TL from New South Wales, Australia; and (C)
Squalus brevirostris
,
KAUM-I 185, female, 500 mm TL from Kagoshima, Japan.
Doubts also exist concerning the precise
type
locality of
S. acutipinnis
as
Regan (
1908
a:
241
)
cited two different localities, one as Bird Island near Algoa Bay in
South Africa
and the second as Kwazulu-Natal,
South Africa
. Both localities are written on the label of the
type
specimens. Some previous authors have mentioned the
type
locality as being either Algoa Bay, Bird Island or Kwazulu-Natal, such as
Merrett (
1973
)
who considered the former locality as being that of the
lectotype
. Kwazulu-Natal is clearly the
type
locality of
S. acutipinnis
as indicated in the original description as well as being the locality of the
lectotype
later designated by
Krefft (
1968
)
, whereas Bird Island should probably be considered an error.
DISCUSSION
Analysis of the
type
series of
S. acutipinnis
revealed relevant morphological variation between the
lectotype
and
paralectotypes
(
Figs. 1
,
7
): the proportional distance between first dorsal-fin origin and pectoral-fin origin
1.4
times preorbital length in the
lectotype
vs.
0.7–1.1
times in the
paralectotypes
; first dorsal-fin base length
1.3
times preorbital length vs.
0.9–1.2
times; fifth gill slit
1.5
times longer than first gill slit vs.
1.1–1.2
times; dermal denticles more slender at crown base, their length somewhat equal to width, and with asymmetrical lateral expansions in the
lectotype
vs. denticles broader at crown base with their length greater than width, and symmetrical lateral expansions; and continuous caudal fork between lobes vs. evident discontinuous caudal fork. The
types
are also very distinct in dentition: upper teeth wide in
lectotype
vs. more slender in
paralectotypes
; lower teeth with thick and slightly elongated cusp, directed upwardly vs. lower teeth wider and depressed, with cusp very short and somewhat oblique; concave mesial cutting edge vs. straight mesial cutting edge; pointed mesial heel vs. rounded mesial heel; apron shorter in upper teeth than in lower teeth vs. very short apron in both jaws (
Fig.
2
). Vertebral counts also show variation in the
types
of
S. acutipinnis
, with greater disparity in the precaudal vertebrae (
81 in
lectotype
vs.
84
) and caudal vertebrae (
27
vs.
25
;
Table
2
).
Fig. 9. Shape of pectoral fin (A, D, G), first dorsal fin (B, E, H), and second dorsal fin (C, F, I): (A, B, C)
Squalus acutipinnis
, SAIAB 34576, female, 578 mm TL from Kwazulu-Natal, South Africa; (D, E, F)
Squalus brevirostris
, HUMZ 189762, male, 403 mm TL from East China Sea; (G, H, I)
Squalus megalops
, AMS I 45658-001, female, 625 mm TL from New South Wales, Australia.
Our analysis of the
type
specimens of
S. acutipinnis
, therefore, clearly indicates that
Regan (
1908
a)
based the original description on a combination of two different species that are not sympatric and clearly separable from each other by external morphology and measurements. Morphological variation in the
type
series of
S. acutipinnis
has not been previously reported and has doubtlessly contributed to the taxonomic confusion concerning the identity and validity of this species. One of the species of the
type
series is illustrated in the original description as the representative of
S. acutipinnis
, which refers to the
lectotype
(
BMNH
1905.6
.
8.8
, female,
578 mm
TL) from Kwazulu-Natal (
South Africa
) as well as to a stuffed
paralectotype
(
BMNH
1881
.
3.11
.
2
, female,
852 mm
TL) from
Mauritius
(previously considered missing by
Krefft,
1968
). The other two remaining
paralectotypes
of
S. acutipinnis
(
Fig.
7
) represent an undescribed species of
Squalus
that is under investigation as part of a taxonomic revision of all species of
Squalus
(Viana and Carvalho, unpubl.).
Another factor that may have contributed to the confusion concerning the validity of
S. acutipinnis
is the attempt by some authors to recognize only species groups of
Squalus
in the region (e.g.,
Bass et al.,
1976
;
Compagno,
1984
) rather than attempt to better define morphologically the species present off
South Africa
. This may have, unintentionally, obscured relevant diagnostic characters of
S. acutipinnis
, contributing to its status as a synonym of other nominal species that have wide geographical distribution such as
S. megalops
and
S. mitsukurii
(e.g.,
Chen et al.,
1979
;
Compagno,
1984
).
Regan (
1908
b)
emphasized that
S. acutipinnis
was clearly separable from
S. megalops
(
type
locality: Port Jackson, New South
Wales
,
Australia
) from Southern
Australia
and Tasmania by not having acutely pointed pectoral fin free rear tips and straight pectoral posterior margin, which reaches the level of the first dorsal fin insertion, features corroborated as diagnostic in our study. These species clearly differ from each other by pectoral fin shape, which is also consistently narrower in
S. megalops
than in
S. acutipinnis
(
Figs. 8
,
9
). The former has conspicuously rounded and lobe-like free rear tips, pectoral fin apex transcending its free rear tip, and pectoral-fin posterior margin never transcending trunk height when adpressed on body, confirming the observation by previous authors that
S. acutipinnis
has longer pectoral fins than
S. megalops
(e.g.,
Krefft,
1968
).
Squalus acutipinnis
is also very distinct from the
holotype
of
S. megalops
by having an arched mouth (vs. relatively straight mouth), continuous caudal fork between lobes (vs. discontinuous caudal fork), and pelvic fins with pointed and triangular free rear tips (vs. pelvic fins with very rounded and lobe-like free rear tips).
Table 1. External measurements expressed as percentage of the total length (% TL) for the type specimens of
Squalus acutipinnis
,
Squalus megalops
,
and
Squalus brevirostris
. Ranges for other specimens are also provided. Total length is expressed in millimeters. A: BMNH 1881.3.11.2; B: BMNH 1859.5.7.68; C: BMNH 1900.11.6.14; L: lectotype; H: holotype;
n
: number of specimens; x: mean; SD: standard deviation.
|
Squalus acutipinnis
|
Squalus megalops
|
Squalus brevirostris
|
|
Character
|
L
|
A
|
B C
n
Range
|
x
|
SD
|
H
|
n Range x
|
SD
|
H
|
n Range x
|
SD
|
| TL (mm) |
578 |
852 |
190 565 8 310-695 |
525.6 |
110.8 |
550 |
10 220–625 442.2 |
139.3 |
426 |
8 275–578 431 |
90.3 |
| PCL |
79.9 |
81.2 |
76.8 80.2 8 75.8–80 |
78.6 |
1.3 |
90.4 |
10 75–80.3 78.5 |
1.4 |
79.8 |
8 78.9–81.3 79.5 |
0.8 |
| PD2 |
61.1 |
64.9 |
55.4 61.1 8 58.1–63.5 |
61.4 |
1.7 |
71.6 |
10 58.9–62.7 61.3 |
1.5 |
61.7 |
8 60.6–63.8 62.1 |
1.1 |
| PD1 |
31.3 |
27.9 |
29.6 28 8 28.6–31.3 |
29.9 |
1 |
34.5 |
10 28.7–31.4 29.9 |
0.9 |
29.6 |
8 28.5–31 29.5 |
0.8 |
| SVL |
49.8 |
53.4 |
46.1 48.1 8 45.8–50.4 |
48.5 |
1.7 |
57.8 |
10 44–51.8 47.9 |
2.3 |
47.7 |
8 45.4–49.5 46.8 |
1.5 |
| PP2 |
45.8 |
49.6 |
43.8 45.3 8 42.6–48.7 |
46.1 |
2.3 |
54.9 |
10 43.2–50.1 45.9 |
2.2 |
43.7 |
8 42.4–46.9 44.2 |
1.5 |
| PP1 |
22.5 |
19.4 |
22.1 22.7 8 19.4–23.6 |
21.6 |
1.4 |
23.7 |
10 20.2–24 21.8 |
1.2 |
21.7 |
8 19–22.9 21.1 |
1.2 |
| HDL |
23.1 |
20.2 |
24.3 23 8 21.4–24.3 |
23.1 |
0.9 |
24.7 |
10 21–24.8 22.5 |
1.4 |
21.9 |
8 20–23.5 22 |
1.1 |
| PG1 |
18.8 |
16.2 |
19.1 19.1 8 17.7–19.3 |
18.7 |
0.6 |
22.3 |
10 17.4–20.3 18.9 |
1 |
17.9 |
8 16.8–19.1 18.1 |
0.7 |
| PSP |
11.6 |
11.2 |
13.1 11.9 8 7.7–12.1 |
11.2 |
1.5 |
13.5 |
10 11.6–13.4 12.6 |
0.7 |
12.1 |
8 11.3–12.9 12.2 |
0.5 |
| POB |
6.3 |
7.1 |
6.9 7.1 8 6.5–7.1 |
6.8 |
0.2 |
7.5 |
10 6.6–7.7 7.1 |
0.4 |
6.7 |
8 6.6–7.5 7.2 |
0.2 |
| PRN |
4 |
4.4 |
3.5 4.7 8 3.9–4.4 |
4.2 |
0.2 |
4.2 |
10 3.9–5.4 4.5 |
0.4 |
4 |
8 3.8–4.4 4.2 |
0.2 |
| POR |
8.9 |
8.4 |
10.1 9.5 8 8.4–9.2 |
8.9 |
0.3 |
9.7 |
10 8.8–10.7 9.5 |
0.7 |
9.1 |
8 8.4–10 9.1 |
0.5 |
| INLF |
4.7 |
3.7 |
4.8 4.9 8 4.3–4.9 |
4.5 |
0.2 |
5.3 |
10 4.6–5.3 5.1 |
0.3 |
5 |
8 4.7–5.5 5 |
0.3 |
| MOW |
8.5 |
6.8 |
7.5 8.5 8 7.7–9 |
8.3 |
0.4 |
9.6 |
10 7.8–9.4 8.5 |
0.5 |
8.1 |
8 7.5–8.1 7.8 |
0.2 |
| ULA |
2.8 |
1.8 |
2.4 2.4 8 2.5–2.9 |
2.6 |
0.2 |
2.7 |
10 2.2–2.8 2.5 |
0.2 |
2.6 |
8 2–2.7 2.3 |
0.3 |
| INW |
3.8 |
4.5 |
3.7 3.8 8 3.6–4.3 |
4 |
0.2 |
4.5 |
10 3.9–4.8 4.3 |
0.3 |
3.6 |
8 3.4–3.9 3.6 |
0.2 |
| INO |
7.8 |
8.4 |
9.9 8.4 8 7.4–8.6 |
8.2 |
0.4 |
8.7 |
10 8.3–10 8.9 |
0.4 |
8.6 |
8 8–9 8.3 |
0.3 |
| EYL |
5.1 |
3.8 |
5.9 4 8 4.3–5.1 |
4.6 |
0.3 |
5.2 |
10 4.2–6.5 5 |
0.7 |
5 |
8 4.2–5.1 4.6 |
0.3 |
| EYH |
1.5 |
2.5 |
1.7 2 8 1.6–2.4 |
2 |
0.2 |
2.3 |
10 1.9–2.6 2.3 |
0.2 |
2.2 |
8 2–2.6 2.2 |
0.2 |
| SPL |
1.5 |
1.3 |
1.5 1.4 8 1.2–2.2 |
1.6 |
0.3 |
1.1 |
10 1.3–2 1.6 |
0.2 |
1.7 |
8 1.4–1.8 1.6 |
0.2 |
| GS1 |
1.8 |
1.1 |
2.4 2.3 8 1.7–2.4 |
2 |
0.2 |
2 |
10 1.2–2.5 2 |
0.3 |
2.1 |
8 1.5–2.6 2.1 |
0.4 |
| GS5 |
2.7 |
2 |
2.7 2.6 8 2.1–2.6 |
2.3 |
0.2 |
3 |
10 2–2.6 2.4 |
0.2 |
2.3 |
8 2.1–2.6 2.3 |
0.2 |
| IDS |
22.1 |
28.9 |
21.2 25.3 8 20.1–25.4 |
24 |
1.9 |
27.3 |
10 21.3–27.2 24.5 |
1.9 |
24.9 |
8 23.3–27.2 25 |
1.3 |
| DCS |
11.5 |
10.8 |
11.3 11.9 8 10.3–12.3 |
11.1 |
0.7 |
11 |
10 9.6–11.7 10.6 |
0.8 |
10.5 |
8 10–10.6 10.4 |
0.2 |
| PPS |
18 |
23.5 |
18.7 22.3 8 17.8–22.6 |
20.7 |
1.9 |
26.9 |
10 16.8–24.2 20.9 |
2.4 |
21.4 |
8 17.2–22.8 20.3 |
2 |
| PCA |
25.3 |
27.6 |
24.1 25.3 8 24.8–27.2 |
25.7 |
0.7 |
26.4 |
10 22.9–28.1 26.1 |
1.9 |
28.1 |
8 24.6–29.4 27.8 |
1.5 |
| D1L |
13.9 |
13.7 |
12.2 13.3 8 13.4–14.2 |
13.8 |
0.3 |
15.1 |
10 10.9–15.1 13.6 |
1.2 |
13 |
8 13.3–14.7 13.9 |
0.4 |
| D1A |
11.1 |
9.9 |
12.9 10.1 8 11.1–11.8 |
11.4 |
0.3 |
8.9 |
10 10.3–13.3 11.8 |
1 |
10.3 |
8 7.9–12 10.8 |
1.3 |
| D1B |
8.3 |
8.2 |
6.4 8.6 8 7.5–8.5 |
7.9 |
0.4 |
8.5 |
10 7.3–8.8 8.1 |
0.5 |
7.3 |
8 7.4–9.2 8 |
0.6 |
| D1H |
8.2 |
7.1 |
10.2 8 8 8–9.3 |
8.7 |
0.4 |
5.3 |
10 8.1–10.4 8.7 |
0.7 |
7.6 |
8 7.3–8.6 8 |
0.4 |
| D1I |
5.6 |
5.2 |
6.9 4.8 8 5.5–6.5 |
6 |
0.3 |
6.9 |
10 3.6–6.4 5.9 |
0.8 |
5.8 |
8 5.4–6.8 6.1 |
0.5 |
| D1P |
9.6 |
9.2 |
8.5 8.8 8 8.8–10.3 |
9.4 |
0.5 |
8.9 |
10 7.5–9.9 8.8 |
0.7 |
7.7 |
8 8.3–8.8 8.6 |
0.2 |
| D1ES |
1.9 |
4.9 |
2.2 2.4 8 3.5–4.3 |
3.8 |
0.3 |
— |
10 1.8–3.6 2.8 |
0.6 |
— |
7 2.6–4.2 3.5 |
0.5 |
| D1BS |
0.6 |
0.9 |
0.6 0.7 8 0.6–0.9 |
0.7 |
0.1 |
0.8 |
10 0.5–0.8 0.7 |
0.1 |
0.7 |
8 0.5–0.7 0.6 |
0.1 |
| D2L |
11.6 |
10 |
13.1 11.2 8 10.5–13 |
11.6 |
1 |
10.9 |
10 10.4–13.2 12 |
0.9 |
11.6 |
8 11.2–13.2 12.2 |
0.6 |
| D2A |
9.5 |
7.8 |
10.6 9.6 8 8.9–11.3 |
9.6 |
0.8 |
9.5 |
10 8.8–11.5 10.3 |
0.8 |
9.8 |
8 10.3–11.6 10.7 |
0.4 |
| D2B |
6.5 |
6 |
7.1 7.1 8 5.7–7.8 |
6.6 |
0.7 |
7 |
10 5.6–7.9 6.8 |
0.7 |
6.6 |
8 6.1–7.9 7 |
0.5 |
| D2H |
6.1 |
4.6 |
9.1 4.6 8 5.1–6.7 |
5.8 |
0.5 |
5.7 |
10 5.3–7.6 6.2 |
0.6 |
6 |
8 5.7–7 6.2 |
0.5 |
| D2I |
5.1 |
3.9 |
6 4.2 8 4.1–5.7 |
5 |
0.6 |
4.3 |
10 4.3–5.9 5.3 |
0.5 |
5 |
8 4.8–5.6 5.2 |
0.3 |
| D2P |
5.9 |
4.4 |
4.9 4.7 8 4.5–6.2 |
5.4 |
0.6 |
3.9 |
10 4.1–6 5 |
0.6 |
4.3 |
8 4.3–5.3 4.9 |
0.3 |
Table 1. Continued.
|
Squalus acutipinnis
|
Squalus megalops
|
Squalus brevirostris
|
|
Character
|
L
|
A
|
B C
n
Range
|
x
|
SD
|
H
|
n Range x
|
SD
|
H
|
n Range x
|
SD
|
| D2ES |
3.8 |
4.8 |
4.2 5.1 7 4.5–6.3 |
5.2 |
0.6 |
2.5 |
10 3.8–5.2 4.6 |
0.5 |
4.6 |
8 4.8–6.6 5.7 |
0.7 |
| D2BS |
0.6 |
0.6 |
1.2 1.2 8 0.7–1 |
0.8 |
0.1 |
0.9 |
10 0.6–0.9 0.7 |
0.1 |
0.8 |
8 0.7–0.9 0.8 |
0.1 |
| P1A |
17.7 |
13.1 |
16 17.7 8 15.1–18.1 |
16.9 |
1 |
17 |
10 12.7–17 15 |
1.3 |
14.7 |
8 13.2–15.7 14.5 |
0.9 |
| P1I |
9.8 |
6 |
11.2 9.5 8 9.5–11.8 |
10.2 |
0.8 |
10.9 |
10 9.4–10.7 10 |
0.5 |
10.3 |
8 9.9–11.3 10.6 |
0.5 |
| P1B |
4.2 |
6.2 |
4.1 4.8 8 4.6–5.9 |
5.2 |
0.5 |
5.2 |
10 4.3–6 5 |
0.5 |
4.7 |
8 3.8–5.3 4.8 |
0.5 |
| P1P |
13.7 |
11.1 |
10.1 14.2 8 9.9–14.5 |
13.5 |
1.5 |
12.2 |
10 9.8–14.6 12.1 |
1.6 |
10.4 |
8 10.1–11.5 10.7 |
0.5 |
| P2L |
10.7 |
8.7 |
10.6 11.2 8 9.8–12 |
11.1 |
0.7 |
10.9 |
10 6.1–12.7 10.7 |
1.7 |
11.7 |
8 10.3–12.1 11.4 |
0.6 |
| P2I |
5.1 |
5.7 |
5.4 4.9 8 4.2–6.4 |
5.4 |
0.7 |
5.4 |
10 4.9–7 6.1 |
0.7 |
6.1 |
8 4.8–6.6 6 |
0.6 |
|
CDM
|
20.7
|
20.4
|
23.3 20.3 8 19.7–22.8
|
21.3
|
1.1
|
—
|
10 19.5–23 21.4
|
1
|
20.5
|
8 20.2–21.5 20.7
|
0.4
|
|
CPV
|
10.5
|
9.6
|
12.8 10.8 8 10.3–12
|
11.1
|
0.7
|
8.9
|
10 6–12.7 10.9
|
1.8
|
10.1
|
8 10.1–11.5 10.8
|
0.5
|
|
CFW
|
7.2
|
6.2
|
8 6.9 8 6.9–7.5
|
7.2
|
0.2
|
6
|
10 6.8–8.1 7.3
|
0.4
|
6.6
|
8 6.6–7.3 7
|
0.3
|
|
HANW
|
6.4
|
7.1
|
7.5 6.8 8 6.9–8.5
|
7.4
|
0.5
|
7.6
|
10 6.9–8.7 7.4
|
0.5
|
7.7
|
8 6.2–7.5 6.8
|
0.5
|
|
HAMW
|
12.3
|
10.2
|
12.2 12.1 8 10.7–12
|
11.4
|
0.4
|
12.5
|
10 11–13.6 12.2
|
0.6
|
12.1
|
8 10.9–12.7 11.6
|
0.5
|
|
HDW
|
13.1
|
10.7
|
10.9 13.3 8 11.5–13.5
|
12.7
|
0.6
|
14.6
|
10 12.2–15.1 13.7
|
0.9
|
12.1
|
8 11.6–14.1 13
|
0.7
|
|
TRW
|
10.6
|
10.3
|
10.1 10.3 8 9–11.5
|
10.1
|
0.9
|
11.4
|
10 8.7–13.2 11.4
|
1.4
|
8.9
|
8 8.8–12.9 10.7
|
1.7
|
|
ABW
|
7.6
|
8.6
|
9.1 9.6 8 7–9.7
|
8.3
|
1
|
7.2
|
10 7.2–11.1 9.3
|
1.2
|
11.2
|
8 8.1–12.4 9.7
|
1.7
|
|
HDH
|
10.7
|
10.2
|
10.4 10.8 8 9.1–11.2
|
10.1
|
0.7
|
11.4
|
10 9.5–11.5 10.7
|
0.7
|
9.9
|
8 9.3–11.9 10.1
|
0.8
|
|
TRH
|
12
|
10.1
|
9.6 12.2 8 9.2–12.7
|
10.5
|
1.1
|
11.5
|
10 10–12.8 11.5
|
1
|
10.7
|
8 9.4–13.1 10.6
|
1.4
|
|
ABH
|
11.9
|
9.5
|
7.3 11.4 8 8.4–12.4
|
9.9
|
1.2
|
11.6
|
10 9–13.8 11.1
|
1.5
|
10.1
|
8 8.9–13 10.5
|
1.7
|
|
CLO
|
—
|
—
|
— — 1 —
|
1.8
|
—
|
—
|
4 1.3–4.9 3.9
|
1.7
|
3.9
|
4 1.4–5.1 3.9
|
1.7
|
|
CLI
|
— |
— |
— — 1 — |
4.3 |
— |
— |
4 3–7.5 6.2 |
2.2 |
7.1 |
4 3–8.1 6.4 |
2.3 |
Table 2. Meristic data for
Squalus acutipinnis
,
S. megalops
, and S.
brevirostris
. Summarized values for other nominal species of
Squalus
are also provided. A: BMNH 1881.3.11.2; B: BMNH 1900.11.6.14;
n
: number of specimens; SD: standard deviation.
|
Squalus acutipinnis
|
Squalus megalops
|
Squalus brevirostris
|
|
Paralectotypes
|
|
Character
|
Lectotype
|
A B
n
Range Mean SD
|
Holotype
|
n Range Mean SD
|
Holotype
|
n Range Mean SD
|
| Precaudal |
| vertebrae |
81 |
— 84 10 81–83 82 0 |
86 |
8 79–83 81 1 |
— |
3 80–83 82 2 |
| Caudal |
| vertebrae |
27 |
— 25 10 25–29 27 1 |
— |
8 26–30 28 1 |
— |
3 26–30 28 2 |
| Total |
| vertebrae |
108 |
— 109 10 107–111 109 1 |
— |
8 107–111 109 2 |
— |
3 106–112 109 3 |
| Monospondylous |
| vertebrae |
41 |
— 42 10 37–42 40 1 |
40 |
8 39–41 40 1 |
— |
3 39–40 40 1 |
| Diplospondylous |
| vertebrae |
67 |
— 67 10 66–71 69 2 |
— |
8 66–72 68 2 |
— |
3 66–72 70 3 |
| Upper tooth |
| rows (right) |
13 |
13 13 4 12–14 13 1 |
13 |
6 13–14 13 0 |
12 |
3 12–14 13 1 |
| Upper tooth |
| rows (left) |
13 |
12 13 4 11–14 13 1 |
13 |
6 12–13 13 1 |
13 |
3 12–13 12 1 |
| Lower tooth |
| rows (right) |
11 |
— 11 4 10–12 11 1 |
12 |
6 11–12 12 1 |
10 |
3 10–10 10 0 |
| Lower tooth |
| rows (left) |
11 |
— 11 4 10–13 11 1 |
12 |
6 10–12 12 1 |
10 |
3 10–11 11 1 |
| Upper tooth |
| series |
3 |
2 2 4 2–2 2 0 |
2 |
8 2–2 2 0 |
3 |
3 2–2 2 0 |
| Lower tooth |
| series |
2 |
2 2 4 2–3 2 1 |
2 |
8 2–2 2 0 |
2 |
3 1–2 2 1 |
| Source |
present study |
present study |
present study |
Specimens of
S. acutipinnis
further differ from
S. megalops
from Southern
Australia
by external measurements (
Table
1
[single value for
S. megalops
is from
holotype
]): smaller prespiracular length (
11.6
%,
7.7–12.1
% TL vs.
13.5
%,
11.6– 13.4
% TL, respectively); smaller distance between inner margin of nostril and upper labial furrow (
4.7
%,
4.3–4.9
% TL vs.
5.3
%,
4.6–5.3
% TL); smaller interorbital space (
7.8
%,
7.4–8.6
% TL vs.
8.7
%,
8.3
–10.0% TL); greater length of first dorsal spine (
3.5–4.3
% TL vs.
1.8–3.6
% TL) corresponding to at least half of first dorsal fin height (vs. less than half of first dorsal fin height); and second dorsal spine length
0.6
(
0.8
– 1.0) times second dorsal fin height (vs.
0.4
,
0.5–0.8 in
S. megalops
). Despite slightly overlapping, morphometric characters have recently proven useful for distinguishing closely related species of
Squalus
(
Last et al.,
2007
)
.
Last et al. (
2007
)
reported intraspecific variation in
S. megalops
from different regions of
Australia
based mainly on external measurements.
Squalus acutipinnis
differs significantly from the
S. megalops
of these authors by the following characters: greater labial furrow length (
2.8
%,
2.5–2.9
% TL for
S. acutipinnis
vs.
2.1–2.4
% TL and
2.3–2.5
% TL for
S. megalops
from Southeastern
Australia
and Queensland, respectively); smaller internarial space (
3.8
%,
3.6–4.3
% TL vs.
4.3–4.7
% TL and
4.6–4.9
% TL for
S. megalops
from Southeastern
Australia
and Queensland, respectively); higher first dorsal fin (
8.2
%, 8.0–
9.3
% TL for
S. acutipinnis
vs.
6.1– 7.4
% TL,
6.2–6.6
% TL and 7.0–
7.5
% TL for
S. megalops
from Southeastern
Australia
, Queensland, and Western
Australia
, respectively); greater posterior margin of first dorsal fin (
9.6
%,
8.8–10.3
% TL for
S. acutipinnis
vs.
7.6–8.1
% TL and
7.5–8.1
% TL for
S. megalops
from Queensland and Western
Australia
, respectively); higher second dorsal fin (
6.1
%,
5.1– 6.7
% TL for
S. acutipinnis
vs.
3.6–4.6
% TL,
3.2
–4.0% TL, and
3.7–4.3
% TL for
S. megalops
from Southeastern
Australia
, Queensland, and Western
Australia
, respectively); greater length of pectoral anterior margin (
17.7
%,
15.1–18.1
% TL for
S. acutipinnis
vs.
13.6–14.9
% TL,
12.3–12.6
% TL, and
13.7– 15.1
% TL for
S. megalops
from Southeastern
Australia
, Queensland, and Western
Australia
, respectively), and greater length of pectoral inner margin (
9.8
%,
9.5–11.8
% TL for
S. acutipinnis
vs.
7.4–9.2
% TL and
7.7–8.8
% TL for
S. megalops
from Southeastern
Australia
and Queensland, respectively).
Measurements of the
lectotype
of
S. acutipinnis
are clearly distinct from those provided by
Garrick (
1960
)
for
S. megalops
from Southeastern
Australia
, with the exception of preoral distance (
8.9
% TL vs.
8.5–9.2
% TL), dorsal caudal margin length (
20.7
% TL vs.
19.6–22.1
% TL), and precaudal distance (
79.9
% TL vs.
79
.
0–82
.0% TL). These observations are congruent with the results given for
S. megalops
by
Bass et al. (
1976
)
from
South Africa
, indicating its conspecificity with
S. acutipinnis
. These authors probably took into account their definition of the
S. megalops
group for evaluating the taxonomic status of the South African species, rather than the strong differences in measurements apparent between these two species. The synonymy of these two species proposed by
Bass et al. (
1976
)
is unwarranted according to our results that support the validity of
S. acutipinnis
.
The Southern African species is also easily distinct from its regional congeners
S. acanthias
,
S. blainvillei (
sensu
Bass et al.,
1976
)
, and
S. mitsukurii
(
sensu
Compagno,
1984
)
by: short and rounded snout (vs. elongate and pointed snout); broad pectoral fins (vs. narrow pectoral fins); lanceolate dermal denticles (vs. non-lanceolate unicuspid in
S. acanthias
, and tricuspid in specimens identified as
S. blainvillei
and
S.
Table 2
.
Extended.
|
Squalus bucephalus
|
Squalus raoulensis
|
Squalus albifrons
|
Squalus altipinnis
|
Squalus notocaudatus
|
| Holotype Paratypes |
Holotype Paratypes |
Holotype Paratypes |
Holotype Paratypes |
Holotype Paratypes |
| 88 86–89 |
84 85–85 |
89 90–93 |
92 98–98 |
97 94–96 |
| 30 27–28 |
28 27–28 |
30 26–31 |
28 26–26 |
30 29–29 |
| 118 113–117 |
112 112–113 |
119 116–122 |
120 114–114 |
127 123–125 |
| 45 45–45 |
41 41–43 |
45 44–46 |
44 42–42 |
49 47–49 |
| — — |
— — |
— — |
— — |
— — |
| — — |
— — |
— — |
— — |
— — |
| — — |
— — |
— — |
— — |
— — |
| — — |
— — |
— — |
— — |
— — |
| — — |
— — |
— — |
— — |
— — |
| 1 1–2 |
2 — |
2 — |
2 — |
2 — |
| 1 1–2 Last et al. (2007) |
2 — Last et al. (2007) |
2 — Last et al. (2007) |
2 — Last et al. (2007) |
2 — Last et al. (2007) |
mitsukurii
from
South Africa
). Additionally,
S. acutipinnis
differs from
S. acanthias
by lacking white spots dorsally on the body (vs. presence of conspicuous white spots) and having a greater number of precaudal vertebrae (81, 81–
83
vs.
74–81
, respectively). It is also distinct from
S. acanthias
by having anterior margin of nostrils bilobate (vs. anterior margin of nostrils unilobate), first dorsal-fin origin anterior to pectoral free rear tips (vs. first dorsal-fin origin posterior to pectoral free rear tips).
More recently,
Naylor et al. (
2012
a
,
2012
b
), based on mitochondrial genes, indicated that a possible new species might occur in
South Africa
that is distinct from
S. megalops
from
Australia
and more closely related to
S. brevirostris
from
Japan
. Our current study shows that
S
. acutipinnis
is clearly distinct from the Japanese species by (
Figs. 8
,
9
): pectoral fin with rounded free rear tips, not lobe-like, and straight posterior margin (vs. triangular and pointed free rear tips, lobe-like, and strongly concave posterior margin); length of pectoral anterior margin
1.8
,
1.5–1.9
times length of pectoral fin inner margin (vs. length of pectoral anterior margin
1.4
,
1.2–1.5
times length of pectoral inner margin); pre-first branchial length
1.6
,
1.5–2.5
times prespiracular length (vs. pre-first branchial length
1.5
,
1.4–1.5
times prespiracular length); and length of posterior margin of first dorsal fin greater in
S
. acutipinnis
than in
S
. brevirostris
(
9.6
%,
8.8– 10.3
%
TL
vs.
7.7
%,
8.3–8.8
%
TL
, respectively). The pelvic fin of the
lectotype
of
S
. acutipinnis
is located closer to the midline between both dorsal fins, whereas in the
holotype
of
S
.
brevirostris
it is closer to the first dorsal fin.
Squalus
cf.
megalops
(
sensu
Naylor et al.,
2012
a
,
2012
b
) also refers to a new species of
Squalus
from South African waters that was probably also included in the analysis of
Bass et al. (
1976
)
when defining the
S
. megalops
group in the region, an act that further contributed to the taxonomic confusion concerning
S
. acutipinnis
. Current investigation of this apparent new species indicates it exhibits more morphological similarities with
S. megalops
from
Australia
and
S. brevirostris
, rather than with
S. acutipinnis
.
Concerning dentition, the middle tooth is absent in
S. acutipinnis
, contrary to what was reported by
Bass et al. (
1976
)
and
Myagkov and Kondyurin (
1986
)
for distinguishing Southern African species of
Squalus
. This character is rarely efficient in separating species of the genus (e.g.,
Chen et al.,
1979
;
Mũnoz-Chápuli and Ramos,
1989
;
Last et al.,
2007
), as presently noticed for
S. acutipinnis
,
S. megalops
, and
S. brevirostris
.
The clasper of the three species compared here is very conservative in relation to the number of terminal cartilages and the shapes of the beta cartilage, intermediate segment, axial cartilage, and marginal cartilages.
Squalus acutipinnis
is, however, more similar to
S. brevirostris
than to
S. megalops
concerning the terminal cartilages. The former two species have accessory terminal cartilage (spur) thicker and shorter as well as dorsal terminal cartilage (claw) thicker, shorter, and conspicuously concave in its distal portion when compared to
S. megalops
from
Australia
. The internal morphology of the clasper may be useful for distinction at species level in
Squalus
as shown by descriptions of terminal clasper components in species from other regions (
Muñoz-Chápuli and Ramos,
1989
).
Vertebral counts are greatly useful for distinguishing many species of the genus (e.g.,
Springer and Garrick,
1964
;
Last et al.,
2007
;
Table
2
).
Squalus acutipinnis
,
S. megalops
from Southern
Australia
, and
S. brevirostris
present overlap in numbers of vertebrae, even though the
holotype
of
S. megalops
has more precaudal vertebrae than the
lectotype
of
S. acutipinnis
and specimens of
S. brevirostris
. On the other hand,
S. acutipinnis
can be easily distinguished from other congeners such as
S. bucephalus
,
S. raoulensis
,
S. albifrons
,
S. altipinnis
, and
S. notocaudatus
by monospondylous, precaudal, and total vertebrae.
According to
Last et al. (
2007
)
, some specimens of the
S. megalops
group can be placed in the ‘‘highfin
megalops
subgroup,’’ characterized by tricuspid dermal denticles, small snout (6.0–7.0% TL preoral length), high and upright first dorsal fin (
7.7–9.4
% TL height), and heavy dorsal-fin spines (
0.7–1.1
% TL exposed base length). These characters are present in
S. acutipinnis
, except for the shape of the dermal denticles (lanceolate as in some other species of the
Squalus megalops
group) and shape of the dorsal fins. Due to the overlap of characters between the species complexes of
Squalus
, we prefer not to allocate
S. acutipinnis
to a species group. Current investigation of the species of
Squalus
in South African waters (Viana and Carvalho, unpubl.) indicates that the diversity of the genus in both the Atlantic and Indian Oceans is greater than previously recognized.