Squatina guggenheim Marini 1936
Creators: name: Vaz, Diego F. B.
name: De, Marcelo R.
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Elasmobranchii
Squatiniformes
Squatinidae
Squatina
Squatina guggenheim

description: Squatina guggenheim Marini, 1936
(Figs. 12–24; Tabs. 3–4)
Squatina guggenheim Marini, 1936: 19 –30, fig. 2 (original description, Southwestern Atlantic ocean, Necochea, Province of Buenos Aires, Argentina); Vooren and da Silva, 1991: 589–602, fig. 5 (taxonomic revision); Sunye and Vooren, 1997: 86– 94 (anatomical description): Gadig et al., 1999: 133–136 (key to species); Milessi et al., 2001: 1–7, fig. 2a (taxonomic account); Gadig and Gomes, 2003: 27 (listed); Vooren and Klipel, 2005, 57–82, figs. 4.1a, 4.2 (ecological study); Colonello et al., 2007: 131, fig. 7 (ecology); Menni and Lucifora, 2007: 4 (listed); Awruch et al., 2008: 17–28 (ecology); Vogler et al., 2008: 41–52 (ecology); Gomes et al., 2010: 53–54, figs. 55, 57 (identification guide); Stelbrink et al., 2010: 395–404 (molecular phylogeny); Carvalho et al., 2012: 171–183, figs. 2a, 3a, 4a, 5, 6a (description of neurocranium).
Squatina punctata Marini, 1936: 19 –30 fig. 4 (taxonomic revision); Soto, 2001: 97 (misidentification, listed); Gadig and Gomes, 2003: 27 (misidentification, listed); Soto and Mincarone, 2004: 84 (misidentification, listed); Bernardes et al., 2005: 74 (misidentification, taxonomic account); Compagno et al., 2005: 145, plate 18 (misidentification, identification guide).
Squatina?: Marini, 1936: 22, 27 (identification key).
Squatina argentina: Cousseau, 1973: 175 –195 (taxonomic revision); Figueiredo, 1977: 128, fig. 63 (identification); Solé-Cava et al., 1983: 355–358 (isozymic studies, cited as "morphotype I"); Solé-Cava and Levy, 1987: 139–144 (isozymic studies, cited as "morphotype I").
Squatina armata: Norman, 1937: 10 –11 (taxonomic account).
Squatina dumerili: Roux, 1977: 159 –168 (in part, for specimens from Southwestern Atlantic; taxonomic revision); Roux, 1979: 124–125, fig. 9 (in part, for specimens MNHN 1984.032, MNHN1989.0134; taxonomic account).
Squatina squatina:?Schreiner and Miranda Ribeiro, 1903: 80 (taxonomic account);?Miranda Ribeiro, 1907: 169–171, fig. 10 (taxonomic account, figured).
Holotype. MACN 938, juvenile male (670 mm TL), Necochea, Province of Buenos Aires, Argentina (not examined).
Additional material examined. 196 specimens (see Appendix 1).
Diagnosis. A species of Squatina diagnosed by presenting a single (or multiple in juveniles) row of enlarged, conical and morphologically distinct dermal denticles over dorsal longitudinal midline, from midlength of pectoral fin base to origin of first dorsal fin (in some specimens, to origin of caudal fin); dorsal midline denticles with enlarged and rounded basal plate, 3–4 times diameter of other dorsal denticles, their crown with several median ridges (10–12), and crown apex acute and smooth, without ridges (vs. dorsal midline denticles on trunk morphologically similar to other trunk denticles and barely organized in a row in S. occulta and S. argentina)” presence of a pair (or more) of enlarged, morphologically distinct denticles on dorsal origin of pectoral fin, with an enlarged and rounded basal plate two times diameter of other pectoral fin denticles, and with an elongate crown, acute crown apex, without ridges (present in early embryos to adults with 850 mm TL vs. dorsal surface of pectoral fins with denticles morphologically homogeneous, without any sort of enlarged denticles in S. occulta and S. argentina); dorsal color pattern composed of light to dark brown background, with several white, creamy-white or yellowish large and rounded blotches variable in size (between one-half to 1.5 times eye-length) on entire dorsal surface. Squatina guggenheim is further distinguished from S. occulta by having larger and fewer white blotches on dorsal surface, without surrounding blackish rings (i.e. absence of ocelli-like markings), and a smaller size at maturity (from 730 mm to 800 mm TL vs. greater than 1000 mm TL in S. occulta). Squatina guggenheim is distinguished from S. argentina by its ligther background colour (light to dark brown vs. dark brown to reddishbrown, respectively), larger and fewer white blotches over dorsal surface, presence of a pair of enlarged, conical and morphologically distinct dermal denticles between spiracles (vs. interspiracular surface covered by smaller dorsal denticles, without enlarged denticles, see diagnosis above for S. occulta), lower number of tooth rows with 18 to 22 vertical rows in both upper and lower jaws (tooth formula 9-9 to 11-11 / 9-9 to 11-11; vs. 12-12/12- 12 in S. argentina), and a straight external pectoral fin margin (S. argentina with convex anterior half of external margin). S. guggenheim is further distinguished of Squatina sp. by a low number of vertebral centra (maximum values 136 vs. 150, respectively), and by the presence of a pair of enlarged and morphologically distinct dermal denticles between spiracles (vs. pair of conical denticles in interspiracular surface smaller, only slightly enlarged, with a basal plate 1.5 times diameter of other denticles, and crown with four median ridges in Squatina sp.).
Description. Measurements in Tab. 3; meristic data in Tab. 4. Description is based on all specimens. For the description, refer to Figs. 12–24.
External morphology. Body dorsoventrally depressed from head to origin of caudal fin (head height 5.4 to 8.9% TL). Abdomen longer than wide, not tapering abruptly near origin of pectoral and pelvic fins; pectoral-pelvic distance 5.3 to 11.7% TL, width at pectoral origins 12.2 to 16.6% TL, and trunk width 12.1 to 21.2% TL. Head broad, anterior half margin rounded to trapezoidal, and posterior margin straight to concave, projecting obliquely to inner side (Fig. 15 a). Dermal folds extend along entire lateral margin of head, from distal end of ventral labial furrow to superior margin of first gill opening. Dermal fold margins straight to slightly convex in some specimens, without lobes or projections. Snout very short; shape of anterior margin between nostrils slightly convex, straight or concave, with dorsal surface straight or slightly convex. Preorbital length 2.3 to 4.8% TL, without preorbital pit. Eyes small, not greatly protruding above head, elliptical, and slightly obliquely disposed, with posterior margin external to anterior margin (preorbital distance 4.5 to 6% TL, eye-length 1.3 to 2.7% TL, and width 0.8 to 2.2% TL). Eyes widely separated, interorbital distance 6.4 to 9.6% TL; interorbital surface slightly bulging. Spiracles well separated from eyes (eye-spiracle distance 2 to 3.7% TL), wider than long, about equal or slightly larger than eyes (spiracle length 1.2 to 3% TL); spiracles comma shaped, and with a knob on inner half of posterior margin. Interspiracular distance about equal to interorbital length. Generally more than 10 pseudobranchial folds on anterior margin of spiracle (variable depending on preservation).
Nostrils small, terminal on head, approximately one-half length of eye; nostrils greatly separated (distance between nostrils 4.6 to 6.9% TL), and positioned just dorsal to upper lip. Anterior nasal flap very large, overlapping mouth, with three well developed, ventrally directed barbels. Inner and outer barbels elongate, slender and spatulate, as large as nasal aperture; outer barbel slightly wider than inner barbel; median barbel somewhat square, wider than long, with a free fringed margin, about one-half length of outer barbel. Posterior nasal flap slightly fringed, confluent with lateral dermal fold, less prominent than anterior nasal flap, and protruding only slightly from nasal margin. Mouth large, terminal on head, posteriorly arched, and extending to about level of mid-eye length (mouth width 9.9 to 15.1% TL). Upper labial furrows prominent, conjoined, forming a deep preoral groove from symphysis to posterior jaw angle; lower labial furrows smaller than upper, length about one-fourth mouth width. Lower labial furrow extends from posterior mid-length of lower labial cartilage to posterior to jaw angle. Two or three pairs of teeth externally visible in some specimens with mouth closed (e.g. NUPEC 1649, NUPEC 20), but teeth entirely covered in others specimens (e.g. MZUSP 43102). Gill openings covered laterally, but inner edge of slits visible ventrally. Distance between first and fifth gill apertures very short (intergill distance 1.3 to 4% TL). Gill slits widely separated, width between first gill openings 7.5 to 16.3% TL.
Pectoral fins very large, 1.6 to 2 times longer than wide (length 27.1 to 33.6% TL and width 13.9 to 20.3% TL), with slender, angular, anterior projection with acute apex. Anterior margin straight to slightly convex at its anterior half. Posterior margin slightly concave. Inner margin strongly convex, its length slightly shorter than pectoral fin width (mean inner margin length 15.1% TL, pectoral fin width 16.9% TL). Pectoral-fin base length large (8.3 to 12.9% TL), positioned anteriorly on body (pre-pectoral length from 17.1 to 22.3% TL). Pelvic fins elongate, triangular to semi-rhomboidal, much longer than wide (length 20.8 to 27.7% TL and width 10.2 to 17.4% TL). Anterior margin of pelvics straight to slightly convex; posterior and inner pelvic margins straight, with free rear tip bluntly rounded, not reaching origin of first dorsal. Pelvic fin broad at more or less its midwidth, slender on margins. Distal end of pectoral fin reaches anterior margin of pelvic fin. Pectoral distal end usually extends from close to pelvic origin until one-half length of pelvic anterior margin (some specimens with distal end of pectoral fin reaching close to outer edge of pelvic fin; NUPEC 1174, Fig. 14 b).
Clasper elongate and flattened, extending posteriorly more than one-third beyond pelvic free rear tip (in adults, clasper inner length 20.6 to 22.1% TL, outer length 7.9 to 8.5% TL, and width 2.9 to 3.5% TL). Clasper groove (‘gouttière spermatique’ of Capapé and Roux 1980) elongate, slightly curved and extending from apopyle (positioned almost level to pelvic insertion) to hypopyle. Hypopyle positioned at anterior part of clasper glans, between external margin of cover rhipidion and pseudopera. Cover rhipidion (‘repli interne’ of Capapé and Roux 1980) well developed, positioned on inner side of mixopterygium, extending from anterior margin of glans to clasper tip; cover rhipidion width one-half of clasper width. Rhipidion an elongate flap, projecting laterally from base of cover rhipidion, covering dorsally hypopyle, pseudopera, and posterior surface of glans. Pseudopera (‘dorsal pseudosiphon’ of Capapé and Roux 1980), a small blind pouch positioned externally to hypopyle, close to external border of clasper glans. External wall of clasper glans very developed, as tall as cover rhipidion, enclosing the floor of clasper glans and rhipidion (‘ouverture de la gouttiére spermatique’ of Capapé and Roux, 1980). Pseudosiphon absent (also Capapé and Roux, 1980).
Tail elongate, slightly larger than length of head and trunk (cloaca-caudal length 50.6 to 57.2%; mean 53% TL), tail slightly depressed, its width 7.4 to 13.6% and height 3.7 to 7.8% TL. Caudal peduncle strongly depressed, short, without precaudal pit or lateral keels. Dorsal fins similar in size and shape, positioned on tail posterior to pelvic fin rear tip; first dorsal origin close to tail midlength. First dorsal fin slightly taller than second (mean first dorsal fin base length 3.7% TL, height 4.8 % TL; second dorsal fin base length 3.6% TL, height 4.4% TL). Anterior margins of dorsals straight to slightly convex; both inner and outer apices narrowly rounded (Fig. 15 e). Posterior margins slightly convex to straight, generally upright, with posterior inner margin straight. Caudal fin markedly hypocercal, proportionally short; upper lobe margin straight to slightly convex (9.4 to 17.5% TL), lower lobe margin convex and larger than upper (11.8 to 17.6% TL); caudal fin height 9.4 to 15.1% TL. Posterior caudal margin with a prominent notch at midheight, and convex upper and lower margins (Fig. 15 f).
Coloration. Dorsal color pattern in preservative, with mucous removed, with light to dark brown background color, with several white to yellowish rounded blotches symmetrically positioned on entire dorsal surface. Larger blotches present on pectoral and pelvic fins, about 1.5 times eye-length; smaller blotches over head and along trunk and tail about one-half eye-length. Small rounded whitish spots surrounding some larger blotches, forming irregular rosettes (e.g. on pectoral fin of holotype; Fig. 12). Pectoral fin with a common pattern of large blotches: one close to pectoral origin on midlength of pectoral fin base, one on pectoral center at level of its insertion, one close to pectoral fin insertion, and two posteriorly positioned parallel to posterior margin (one on mid-width and another close to inner border; Fig. 18). Pelvic fin with three large blotches, disposed longitudinally on midwidth of fin (one close to origin; one aligned with outer edge and one close to pelvic insertion). On trunk, along lateral line canals, occur three pairs of rounded blotches (some specimens with irregular rosette markings): one pair aligned with pectoral fin insertion, one pair aligned with outer edge of pelvic fin, and a third pair aligned with pelvic insertion. Tail with three pairs of large blackish blotches, their width greater than dorsal fin base, arranged laterally on tail (one pair adjacent to pelvic fin tip, another pair adjacent to first dorsal fin, and third adjacent to second dorsal). On holotype (MACN 0938), whitish blotches over trunk poorly preserved, presenting only the brown background coloration. Large whitish blotches present on pectoral and pelvic fins; on pectoral fins, blotches rounded and wellpreserved, 1 to 1.5 times eye-length. Clasper creamy-white dorsally on inner side of anterior region, from clasper origin to hypopyle, and creamy-white on external side of clasper glans. Light to dark brown on outer side of anterior region of clasper, from pelvic insertion to hypopyle; brownish at rhipidion and cover rhipidion (Fig. 17). Larger male (NUPEC 1649) beige on anterior half of clasper due to squamation after maturation.
Ventral coloration uniform creamy-white on almost entire surface of head and trunk. Pectoral and pelvic fins beige to creamy-white, with outer edge of pectoral fin brownish. Margins of cloaca creamy-white. Tail beige in both juveniles and adults from base to origin of lower caudal fin lobe; tail posteriorly with light to dark brown lateral margins similar to dorsal surface.
Fresh specimens (MZUSP 110868 and MZUSP 110869) with large amount of mucous covering entire dorsal surface (enlarged denticles on head and along dorsal midline barely visible). Mucous light gray, with blackish pigments forming rounded spots exactly over whitish blotches. After removing mucous, dorsal surface coloration quite similar to that in preservative, differing by presenting a brighter background color (Figs. 16 a, 19).
Dentition. Gradient monognathic heterodonty present. Upper jaw teeth proportionally smaller than lower jaw teeth. On upper jaw, teeth of first and second vertical medial rows and that on both distalmost vertical rows slightly smaller than teeth on central vertical row. Teeth of first and second inner rows on lower jaw with roots less wide than other vertical rows; teeth on two distal longitudinal rows proportionally smaller than others. Teeth in 18 to 22 rows in both upper and lower jaws (tooth formula 9-9 to 11-11 / 9-9 to 11-11, mode 10-10/10-10). Embryo (UERJ 831.1) with eight rows in both upper and lower jaws. Tooth row arrangement without lateral overlap, as in S. occulta.
Tooth morphology with main cusp bulky, upright and bent lingually, without serrations and accessory cusplets (Fig. 20). Crown base laterally expanded, with prominent heels, projected diagonally in most teeth (projecting laterally in first vertical upper teeth row). Cusp length greater than width of crown and root. Cutting edges of main cusp and lateral heels sharp, prominent and continuous. Labial face of tooth crown convex. Crown-base with trapezoidal and prominent apron, labially overhanging root but not reaching root base. Crown lingual face convex, contiguous with short, slender and cylindrical uvula covering dorsal surface of root lingual protuberance. Crown base striated near junction with root. Crown-root junction without evident neck collar. Foramina present on crown base, but exact number uncertain. Sexual dimorphism absent.
Dermal Denticles. Dermal denticles densely grouped covering entire dorsal surface, with exception of posterior margins of unpaired fins and anterior apex of pectoral fin (these usually naked). Dermal denticles at central region of trunk and tail usually larger than denticles on head, lateral region of trunk and tail, pectoral and pelvic fins. Dermal denticles with a posteriorly directed crown, with four ridges over entire anterior surface extending from crown base to apex. As in S. occulta, some denticles with a fifth ridge centrally at anterior surface of crown, extending from crown base to its mid-height. Basal plate morphology slightly variable. Trunk and tail denticles with a rounded basal plate, but rhomboidal on pectoral fin; dorsal surface of head with both types of basal plates. At least one pair of morphologically distinct, enlarged denticles on origin of pectoral fin, more evident in juveniles but present in adults over 850 mm TL. Enlarged denticles on pectoral fin origin with enlarged basal plates (two times diameter of other dorsal pectoral denticles), an elongate crown with four ridges extending from crown base to crown mid-height; crown of pectoral fin denticles with smooth acute apex, without ridges.
Single row of enlarged, conical and morphologically distinct dermal denticles along dorsal midline (usually more than one row in juveniles), extending from mid-length of pectoral fin base to origin of first dorsal fin (in some specimens, to origin of caudal fin). A pair of enlarged denticles anterior to origin of first dorsal fin. Dorsal midline denticles with large, rounded basal plates, three to four times diameter of other trunk denticles. Crown conical, projecting posteriorly, with smooth base, several ridges at mid-height, and apex acute and smooth without ridges (Fig. 21). Morphology of these enlarged and conical denticles conservative during all stages of development, but proportionally smaller and less prominent in adults, especially in larger females (diameter of basal plate 1.5 to 2 times diameter of surrounding dorsal denticles; Fig. 17). Size of enlarged midline denticles somewhat variable in adult stages, with specimens similar in total length and sex with midline denticles more prominent (NUPEC 1115) than others (MOFURG 19; holotype MACN 0938). In smaller juveniles, enlarged midline denticles densely grouped, with posterior margin of basal plate meeting anterior margin of denticle immediately posterior. On larger juveniles and adults, midline denticles more spaced apart.
Slightly enlarged, conical dermal denticles (similar to midline denticles) on head symmetrically organized (Fig. 15 a, b), with two rows with three to four enlarged denticles each between nostrils, from anterior margin of snout to anterior margin of eye (directly over lateral magins of anterior fontanelle of neurocranium). Two, but sometimes three, enlarged denticles obliquely positioned anterior to each eye, with anteriormost denticle reaching anterior margin of snout (over posterolateral margins of preorbital processes). A pair of denticles present posterior to each eye (over postorbital process), and a pair of enlarged denticles between spiracles (over sphenopterotic ridge). Enlarged cephalic denticles, similarly positioned, but less prominent and grouped in clusters of five or more denticles in adults (Fig. 15 a).
Sexual dimorphism present. Cluster of enlarged dermal denticles on outer edge pectoral fin in adult males, absent in females (Fig. 15 d). These denticles morphologically similar to denticles on dorsal midline but smaller (about one-half to one-third length of midine denticles) and with lower number of ridges at mid-height of crown. Skin completely smooth around each enlarged denticle of outer edge of pectoral fin.
Maturity and reproductive system. Most specimens analyzed were immature; only nine adults were examined. Smallest adult specimen (MCP 4712) 730 mm TL. Our observations are in agreement with Vooren and da Silva (1991), Vooren and Klippel (2005), Colonello et al. (2007), and Awruch et al. (2008), who described size at maturity for S. guggenheim at about 700 mm TL. However, there is variation in size of maturity. NUPEC 1115 is a male with 778 mm TL in which the claspers are not completely rigid as in other adults, as similarly reported by Colonello et al. (2007) and Awruch et al. (2008).
Although no adult female was dissected, juvenile females present prominent ovaries with discernible oocytes from early stages of development (MZUSP 110871, 400 mm TL). We observed that S. guggenheim presents only one functional ovary, on left side; its antimere is poorly developed, very reduced, and lacking oocytes (Figs. 36 c, d). Size at birth in S. guggenheim was observed to occur between 235 to 250 mm TL, based on several embryos, in concordance with Vooren and Klippel (2005).
Remarks. Unfortunately, we were unable to examine the holotype of S. guggenheim; however, a photograph of the holotype of S. guggenheim was made available by C. M. Vooren, which enabled us to verify some of the diagnostic characters of this species. These include dorsal color pattern with light brown background color, with whitish rounded blotches on pectoral fin varying in size from 1 to 1.5 eye-length (position of whitish blotches described above), without dark surrounding spots (i.e. without ocelli-like markings), and presence of an enlarged row of conical dermal denticles along dorsal midline, features absent in S. occulta and S. argentina.
Compagno et al. (2005) described for this species a dorsal coloration with irregular dark spots that turn white after fixation. Fresh specimens studied here have white spots throughout the body, present since capture. As described above (see coloration), the mucous of S. guggenheim may be pigmented, forming dark spots exactly over some of the whitish blotches (Fig. 19).
Geographical distribution. According to our material, Squatina guggenheim is distributed in the southwestern Atlantic from Rio de Janeiro state, Brazil (approximately 23o S) to northern Argentina (type-locality MACN 0938) (Fig. 23). Colonello et al. (2007) and Awruch et al. (2008) report S. guggenheim in the coastal system of ‘El rincón’ and off Patagonia (approximately 42o S). Vooren and Klippel (2005) proposed, based on bibliographic reports, that S. guggenheim may be present along the Argentinean shelf (until 45o S), however this could not be confirmed in the present study.
description: Published as part of Vaz, Diego F. B. & De, Marcelo R., 2013, Morphological and taxonomic revision of species of Squatina from the Southwestern Atlantic Ocean (Chondrichthyes: Squatiniformes: Squatinidae), pp. 1-81 in Zootaxa 3695 (1) on pages 19-34, DOI: 10.11646/zootaxa.3695.1.1, http://zenodo.org/record/284327