Squalus quasimodo, De, Sarah T., De, Marcelo R. & Gomes, Ulisses L., 2016

De, Sarah T., De, Marcelo R. & Gomes, Ulisses L., 2016, Taxonomy and morphology of species of the genus Squalus Linnaeus, 1758 from the Southwestern Atlantic Ocean (Chondrichthyes: Squaliformes: Squalidae), Zootaxa 4133 (1), pp. 1-89 : 58-66

Squalus quasimodo sp. nov.

( Figs. 35–41 ; Tables 7–8 )

Suggested common names: Humpback Western dogfish; cação-bagre-corcunda (Portuguese)

Squalus blainvillei (not Risso): Regan, 1908 (in part): 45, 47 (identification key, listed); Bigelow & Schroeder, 1948: 454, 455 (cited, identification key; Brazil); Lucena & Lucena, 1981: 2, 4, 5, fig. 3 (listed; Brazil); Compagno, 1984: 110, 115, 116 (revision; global); Menni et al., 1984: 84 (listed; Argentina, Uruguay); Muñoz-Chápuli, 1985: 397, 398, fig. 1 (cited); Muñoz-Chápuli & Ramos, 1989: 21, figs. 1, 2B, 3B (revision; Eastern Atlantic); Canizarro et al., 1994: 113 (cited); Nion et al., 2002: 4 (listed); Meneses & Paesch, 2003: 8, 25 (cited; Argentina, Uruguay); Compagno et al., 2005 (in part): 74, 75, pl. 3 (description; global); Lamilla & Bustamante, 2005: 9, 26 (listed; Chile); Saéz et al., 2010: 623 (identification key; Chile); Viana, 2011 (in part): 57–91, figs. 18–34 (revision; Brazil); Rosa & Gadig, 2014: 92 (listed; Brazil).

Squalus fernandinus (not Molina): Garman, 1913: 195 (description); Fowler, 1936: 71 (description; South Atlantic); Bigelow & Schroeder, 1948: 478 –480 (revision; Northwestern Atlantic); Bigelow, Schroeder & Springer, 1953: 220–222 (cited; Western Atlantic); Bigelow & Schroeder, 1957: 32 –36 (description); Menni et al., 1984: 62 (identification key; Argentina and Uruguay); Myagkov & Kondyurin, 1986: 13, 14 (revision; Atlantic).

Squalus lebruni: Myagkov & Kondyurin, 1986: 1 –20, fig. 2 (revision; Atlantic).

Squalus mitsukurii (not Jordan & Snyder): Calderón, 1994: fig. 5B (cited; Brazil); Lessa et al., 1999: 61, 150 (cited, listed; South Brazil); Haimovici et al., 2003: 38, 39 (cited); Compagno et al., 2005: 77 –78, pl. 3 (description; Southeast Brazil); Jablonski et al., 2006: 177 (cited); Louro & Rossi-Wongtschowski, 2007: 18, 27, 28, 30, 49 (cited); Menni & Lucifora, 2007: 3 (listed).

Squalus sp. of the blainvillei group: Gomes et al., 1997: 93 –95, 109 (description; Brazil); Marques, 1999 (cited; Brazil).

Squalus of the blainvillei / mitsukurii group: Gadig, 2001 (in part): 29, 36, 54, 55, 57, 58, fig. 29 (listed; Brazil).

Squalus sp. B: Soto, 2001: 96 (listed; Brazil); Soto & Mincarone, 2004: 79 –82 (listed; Brazil).

Squalus sp. 1: Gomes et al., 2010: 44, 45 (cited; Brazil).

Holotype. MZUSP 118707 (formerly, UERJ 1111), adult female, 700 mm TL, off the coast of Rio Grande do Sul, Brazil.

Paratypes (3 specimens). UERJ 1741, adult female, 850 mm TL, Revizee sta. 6089 (nearest station 6088, 89.8W, 33S), Brazil; UERJ 1819, adult female, 740 mm TL, Revizee sta. 6104 (nearest station 6102, 62W, 20.8S), Brazil; MCP 773, juvenile female, 660 mm TL, between coast of Rio Grande do Sul state, Brazil and Uruguay.

Diagnosis. A species of Squalus from the SWAO that can be distinguished from its congeners through a combination of characters: body conspicuously robust and humped dorsally; second dorsal fin upright and markedly tall (its height 4.0%, 4.7%–5.3% TL); first and second dorsal-fin spines elongate (first dorsal-fin spine length 4.3%, 3.3%–4.3% TL; second dorsal-fin spine length 4.4%, 3.9%–4.3% TL), and broad at base (first spine base length 0.9%, 0.7%–1.0% TL; second spine base length 1.0%, 0.8%–0.9% TL); caudal fin with conspicuous rectangular dorsal lobe; and dermal denticles tricuspid, markedly imbricate and broad at crown. Squalus quasimodo sp. nov. differs from S. bahiensis by having a larger pectoral-fin anterior margin length (15.9%, 15.5%– 16.0% TL vs. 14.3%, 14.4%–14.5% TL, respectively) and more elongate first dorsal-fin spine (length 4.3%, 3.3%– 4.3% TL vs. 2.8%, 2.9%–3.0% TL). Squalus quasimodo sp. nov. has a larger first dorsal fin than S. bahiensis with a greater anterior margin length (11.2%, 10.8%–11.4% TL vs. 10.5%, 10.3%–10.6% TL, respectively) and fin base (length 8.2%, 7.7%–8.5% TL vs. 7.5%, 7.2%–7.3% TL, respectively). Squalus quasimodo sp. nov. is clearly distinct from S. lobularis by having a greater interdorsal distance (26.4%, 24.0%–25.8% TL vs. 22.3%, 21.9%– 23.6% TL, respectively).

Description. External morphology. Measurements and meristic data are summarized in Tables 7–8 . Body markedly robust and humped dorsally, more slender from pelvic fins to caudal fin; body extremely deep from head to tail (head width 1.0, 0.8–1.0 times trunk height and 0.9, 0.7–1.2 times abdomen height), very wide at head (head width 1.2, 1.2–1.4 times greater than trunk width, and 1.7, 1.3–1.9 times greater than abdomen width). Head flattened dorsally from snout to spiracle and elongate, its length 24.7% (22.2%–23.0% TL), corresponding to 1.3 (1.0–1.1) times dorsal caudal margin length. Snout strongly pointed at tip and elongate (preorbital length 7.9%, 6.8%–7.7% TL); anterior margin of nostrils broad and bilobate, placed ventrolaterally in snout; prenarial length 1.0 (1.0–1.1) times distance from nostrils to upper labial furrow and 1.4 (1.0–1.4) times larger than eye length; width between nostrils narrow (length 5.0%, 3.9%–4.1% TL), corresponding to 1.4 (0.8–1.2) times eye length. Eyes oval with anterior margin convex and posteriorly notched, very large, its length 3.5%, 3.1%–4.9% TL and corresponding to 2.6 (2.2–3.3) times its height. Prespiracular length 12.8% (11.5%–12.6% TL), corresponding to 1.6 (1.6–1.7) times preorbital length. Spiracles crescent-shaped, located posterodorsally to eyes and very wide, their length 1.3% (1.1%–1.4% TL). Prebranchial length 20.7%, 17.4%–19.2% TL. Gill slits vertical, markedly tall (fifth gill slit height 1.1, 1.1–1.2 times first gill slit height), placed laterally just before pectoral fins.

Preoral length 1.3 (1.2–1.4) times mouth width. Mouth straight and strongly broad, its width 1.6 (1.8–2.0) times greater than internarial space; upper labial furrow elongate, its length 2.6% (2.2%–2.5% TL) with prominent fold; lower labial furrow also long, although not supporting a fold. Teeth unicuspid, similar in both jaws, alternate, compressed and wide labial-lingually at crown; lower teeth markedly larger and taller than upper teeth; cusp pointed, somewhat elongate and thick, oblique, directed laterally; mesial cutting edge conspicuously convex (straight on lower lateral teeth); mesial heel notched; distal heel rounded; apron short and heavy; two series of functional teeth in upper and lower jaw; tooth rows from 14–14 (14–14 paratypes) in upper jaw and 11–11 (11–11 paratypes) in lower jaw ( Fig. 37 ).

Pre-first dorsal fin length 32.9% (28.4%–31.8% TL), its origin well before the vertical line through pectoral free rear tips. First dorsal fin very large (length 2.2, 1.9–1.9 times greater than height), and upright, with anterior margin convex, posterior margin straight, although convex from its midline to more slender apex ( Fig. 38 ); conspicuously rounded and slender at apex, free rear tip rounded; first dorsal-fin anterior margin length 11.2% (10.8%–11.4% TL); posterior margin length 9.4% (7.7%–8.4% TL); first dorsal fin markedly tall, its height 0.8 (0.9–1.0) times preorbital length and 1.1 (1.1–1.3) times its inner margin length. First dorsal-fin spine stout and large, its length 4.3% (3.3%–4.3% TL), corresponding to 0.7 (0.5–0.6) times first dorsal-fin height (not reaching fin apex). Interdorsal space 1.1 (1.1–1.2) times prepectoral length and 2.2 (2.1–2.3) times greater than dorsalcaudal space. Pre-second dorsal fin length 4.0 (3.9–3.9) times pectoral anterior margin length and 3.2 (2.8–3.1) times dorsal-caudal margin length. Second dorsal fin also upright with anterior margin convex, posterior margin straight but convex and falcate from midline to apex ( Fig. 38 ); apex slightly rounded; free rear tip pointed; second dorsal fin large (its length 12.0%, 11.1%–12.5% TL) and tall, its height 4.0% (4.7%–5.3% TL), corresponding to 0.9 (1.0–1.1) times its inner margin length. Second dorsal-fin spine heavy and large, its length 4.4% (3.9%–4.3% TL), corresponding to 1.1 (0.8–0.9) times second dorsal-fin height (almost reaching fin apex); second dorsal-fin spine 1.0 (1.0–1.2) times greater than first dorsal-fin spine.

Pectoral fins with anterior margin straight, inner margin convex and posterior margin concave and fringed; apex and free rear tips rounded and lobe-like ( Fig. 36 ); apex exceeding horizontal line through free rear tip (or reaching it in paratypes); pectoral fins conspicuously broad, its posterior margin length 12.3%, 10.2%–12.5% TL and corresponding to 1.1 (0.9–1.3) times trunk height; pectoral fin also very large, its anterior margin length 15.9% (15.5%–16.0% TL) or 1.5 (1.8–2.0) times greater than its inner margin length. Pectoral-pelvic space 0.8 (0.8–0.9) times pelvic-caudal space. Pelvic fins nearer to second dorsal fin than first dorsal fin, although it is nearest to first dorsal fin in young paratypes. Pelvic fins very broad and elongate, its length 11.3% (9.9%–11.2% TL); all margins straight, although posterior margin fringed; free rear tips markedly pointed.

Caudal keels very strong, placed laterally in caudal peduncle from second dorsal fin insertion to upper precaudal pit; upper and lower precaudal pits profound. Caudal fin elongate, its dorsal caudal margin 19.7% (20.2%–21.3% TL), corresponding to 0.8 (0.9–1.0) times head length and 1.8 (1.7–1.8) times greater than preventral caudal margin length; upper caudal lobe conspicuously rectangular with dorsal caudal margin straight, upper postventral caudal margin convex, turning markedly convex at tip; posterior caudal tip slightly rounded ( Fig. 39 ); preventral caudal margin convex, its length 2.3 (2.3–2.6) times larger than pelvic inner margin length; lower postventral caudal margin straight; ventral caudal tip rounded; caudal fin strongly broad at fin web, its caudal fork width 7.2% (6.6%–7.1% TL); caudal fork between lobes strongly notched.

Dermal denticles ( Fig. 40 ). Denticles triscupid and markedly imbricate with pointed cusps, and lateral cusps much shorter than median cusp; denticles very broad at crown, their length greater than width; median projection prominent and rounded, located anteriorly at crown with small lateroposterior expansions on each side; two prominent lateral ridges on each side, reaching the lateral cusp; single median ridge conspicuous and elongate, bifurcated anteriorly, forming a profound groove in between.

Coloration ( Figs. 35 , 36 ). Body dark brown dorsally and pale ventrally. First and second dorsal fins also dark brown, whitish near each fin base and slightly blackish at apex; first and second dorsal-fin spines light brown, white at tip and dark brown anteriorly. Pectoral fins dark brown with posterior margin white, not uniform. Pelvic fins also brownish, lighter ventrally; pelvic posterior and inner margins white. Caudal fin dark brown, whitish near the vertebral column; dorsal caudal margin white; upper and lower post-ventral margins slightly white; faded black caudal stripe in preserved specimens.

Vertebral counts ( Table 8 ). Monospondylous vertebrae 45 in holotype (46 in paratypes); diplospondylous vertebrae 71 (74–75); precaudal vertebrae 87 (91–92); caudal vertebrae 29 (29 paratypes); total vertebrae 116 (120–121).

Geographical distribution. Squalus quasimodo is so far known as an endemic species in southern Brazil ( Fig. 41 ).

Etymology. Named for the hunchback of Notre-Dame from the 19th Century novel by Victor Hugo, in obvious reference to its most noticeable character.

Remarks. Squalus fernandinus Molina, 1782 was described from Juan Fernandez, Chile, but was reported to occur in the Atlantic (e.g. Miranda Ribeiro, 1907; Fowler, 1936, 1941; Bigelow & Schroeder, 1948, 1957). The taxonomic confusion regarding this species is due to its concise original description, lack of type specimens, and lack of illustration. Guichenot (1848) considered S. fernandinus as a senior synonym of Squalus fernandezianus described by him from Chilean waters, which is characterized by a brownish, robust body, first dorsal fin placed above the pectoral free rear tips, triangular dorsal fins, and pelvic fins located at the midline between the dorsal fins. Later, this species was often considered as either a junior synonym of S. acanthias or a senior synonym of S. blainvillei (e.g. Bigelow & Schroeder, 1948; Garman, 1960; Compagno, 1984). Since then, S. blainvillei has been identified in the Southwestern Atlantic Ocean while the taxonomic status of both S. fernandezianus and S. fernandinus remained uncertain. Our results clearly indicate no conspecificity between S. quasimodo and the original descriptions of S. fernandezianus and S. fernandinus that could suggest the validity of the Chilean species. An exhaustive investigation of these two nominal species from Chile is needed to elucidate their taxonomy in the South Pacific and South Atlantic oceans.

Squalus griffini is another species from the South Pacific Ocean, apparently endemic to the coast of New Zealand ( Duffy & Last, 2007). Squalus griffini also has dorsal spots on the body that are also mentioned in the description of S. fernandinus , indicating that the latter species may also be a senior synonym of S. griffini . Its distribution in the opposite side of the Pacific Ocean is not yet reported (e.g. in Chile). Squalus quasimodo is very similar morphologically to S. griffini , sharing characters such as tricuspid and imbricate dermal denticles that are strongly broad at crown, and absence of dark caudal bar, as well as overlapping in a variety of external measurements and vertebral counts ( Table 12 ). Squalus quasimodo differs from S. griffini in lacking black spots dorsally on body (variable in S. griffini ) and caudal fin with broad white posterior margin, and by having a more slender first dorsal fin. It is also distinct from S. griffini (data from Duffy & Last, 2007) by having a shorter prenarial length (4.8%, 4.5%–4.9% TL vs. 5.2%, 5.0%–5.9% TL in S. griffini ), and more elongate pectoral-fin inner margin (length 10.9%, 8.1%–8.8% TL vs. 6.5%, 5.4%–7.7% TL in S. griffini ).

Squalus quasimodo is also distinct from the Japanese S. mitsukurii ( Table 5 ) by lacking a dark caudal bar, and having a narrower interorbital space (8.8%, 7.7%–8.0% TL vs. 9.3%, 9.1%–9.8% TL in S. mitsukurii ). It differs from S. blainvillei of the Mediterranean Sea by its robust and markedly arched body (vs. slender and straight body) and triscuspid dermal denticles (vs. lanceolate denticles).

Squalus quasimodo is distinct from S. lobularis by having a shorter second dorsal-fin spine (length 4.4%, 3.9%–4.3% TL vs. 5.3%, 3.4%–5.3% TL in S. lobularis ), and second dorsal-fin spine length 1.0 (1.0–1.2) times greater than first dorsal-fin spine length (vs. 1.4, 1.0–1.6 times in S. lobularis ). Squalus quasimodo also has slightly shorter prenarial and preoral lengths than S. bahiensis (prenarial length 4.8%, 4.5%–4.9% TL vs. 5.0%, 4.9%–5.1% TL in S. bahiensis and preoral length 10.2%, 9.5%–10.0% TL vs. 9.9%, 10.2%–10.5% TL in S. bahiensis ).

Squalus quasimodo has a larger number of monospondylous vertebrae than S. crassispinus , S. megalops , S. raoulensis , S. grahami , S. nasutus , and S. hemipinnis based on data provided by Last et al. (2007) ( Table 12 ): 45, 46 in S. quasimodo vs. 41, 39– 42 in S. crassispinus , 37–40 in S. megalops , 41, 41– 43 in S. raoulensis , 40, 38– 42 in S. grahami , 39, 36– 39 in S. nasutus , and 36, 35– 38 in S. hemipinnis . It is also distinguished from S. mitsukurii , the Mediterranean S. blainvillei , and S. chloroculus , S. montalbani , and S. notocaudatus of Last et al. (2007) by total vertebrae (116, 120– 121 in S. quasimodo vs. 112–113 in S. mitsukurii 111 in S. blainvillei , 114, 111– 115 in S. chloroculus , 105–114 in S. montalbani , and 127, 123– 125 in S. notocaudatus ) ( Table 12 ). It is distinct from S. albifrons , S. altipinnis , and S. notocaudatus (data from Last et al., 2007) by having a lower first dorsal fin, its height 4.0%, 4.7%–5.3% TL in S. quasimodo vs. 8.6%, 7.7%–8.9% TL in S. albifrons , 7.8%, 7.9% TL in S. altipinnis , and 8.2%, 8.3%–9.4% TL in S. notocaudatus ).

Analysis of the claspers of S. quasimodo are needed to better characterize this species, as no adult males were found in the fish collections visited by the authors. More specimens are required for comparisons of skeletal anatomy, including neurocranium, with congeners.

Comparative material. Squalus mitsukurii : same material listed for S. lobularis . Squalus blainvillei : same material listed for S. bahiensis .

Figures

FIGURE 35. Holotype of Squalus quasimodo sp. nov. (MZUSP 118707, adult female, 700 mm TL) in lateral view. Scale bar: 50 mm.

FIGURE 36. Squalus quasimodo sp. nov. in ventral view. (A) holotype (MZUSP 118707, adult female, 700 mm TL); (B) paratype (UERJ 1741, adult female, 850 mm TL); (C) paratype (UERJ 1819, adult female, 740 mm TL). Scale bar: 50 mm.

FIGURE 37. Upper (A) and lower (B) teeth of holotype of Squalus quasimodo sp. nov. (MZUSP 118707, adult female, 700 mm TL). Scale bar: 2 mm.

FIGURE 38. First dorsal fin (A) and second dorsal fin (B) of holotype of Squalus quasimodo sp. nov. (MZUSP 118707, adult female, 700 mm TL). Scale bar: 20 mm.

FIGURE 39. Caudal fin of Squalus quasimodo sp. nov. (A) holotype (MZUSP 118707, adult female); (B) paratype (UERJ 1741, adult female); (C) paratype (UERJ 1819, adult female). Scale bar: 20 mm.

FIGURE 40. Dermal denticles of holotype of Squalus quasimodo sp. nov. (MZUSP 118707, adult female, 700 mm TL). Scale bar: 200 ìm.

FIGURE 41. Map of the Southwestern Atlantic Ocean off southern Brazil, showing, showing the type locality of Squalus quasimodo sp. nov. Black star: location of holotype; reddish triangle: location of paratype.