Squatina

Vaz, Diego F. B. & De, Marcelo R., 2013, Morphological and taxonomic revision of species of Squatina from the Southwestern Atlantic Ocean (Chondrichthyes: Squatiniformes: Squatinidae), Zootaxa 3695 (1), pp. 1-81 : 45-49

Squatina sp.

( Figs. 32–36 ; Tabs. 7–8)

Squatina dumeril: Nunan and Senna, 2007: 174 , pl. III d (misidentification, in part, only MNRJ 30190).

Material examined. MNRJ 30190, juvenile female (690 mm TL), continental shelf of Bahia state, Brazil, 19º42’67’’S, 38º37’29’’W.

Note. A putative new species of Squatina is here reported from a single juvenile female from the continental shelf of Bahia state, Brazil. The specific characteristics of this individual were not found in any specimen of other species of Squatina . However, a more complete redescription of Squatina dumeril along with more specimens of this form are needed before it can be confidently described as a new species.

Diagnosis. Squatina sp. is distinguished from all Eastern South American species by an elevated number of vertebral centra (maximum total vertebrae in Squatina sp. 150 vs. 136 to 138 in S. occulta , S. guggenheim and S. argentina ). Squatina sp. is further distinguished from S. argentina by presenting 18 tooth rows in upper jaw and 20 in lower jaw (tooth formula 9-9/10-10 vs. 12-12/12- 12 in S. argentina ), and a lighter background color (light brown vs. dark to reddish-brown, respectively). Squatina sp. is further distinguished from S. guggenheim and S. occulta by presenting two functional ovaries (only one ovary is functional in S. guggenheim and S. occulta ), and by having a pair of slightly enlarged dermal denticles between spiracles (their basal plates 1.5 times diameter of dorsal denticles) with morphology similar to other dorsal denticles (instead of enlarged and conical dermal denticles between spiracles as in S. occulta and S. guggenheim ). Additionally, Squatina sp. is distinguished from S. occulta by lacking blackish spots surrounding white spots over dorsal surface (absence of ocelli-like markings), and from S. guggenheim by lacking a row of enlarged and conical dorsal midline denticles. Squatina sp. is distinguished from Squatina dumeril by presenting a median rectangular lobe on nasal barbels (nasal barbels somewhat reduced in S. dumeril ) and by its dorsal coloration that lacks blackish spots (present in S. dumeril ).

Comments on the morphology of Squatina sp. General aspects of external morphology very similar to others species of Squatina , including measurements, but Squatina sp. differs slightly from S. guggenheim by having a longer pectoral fin ( Squatina sp. 34.9% TL vs. 27.1 to 33.6% TL in S. guggenheim ), and from S. argentina by its longer anterior margin of first and second dorsal fins (first dorsal fin 8.9% TL, second dorsal 8.2% TL vs. first dorsal 7.5 to 8% TL and second dorsal 6.8 to 7.7% TL in S. argentina ). However, due to the range of variation reported for other species and the absence of a representative series of specimens to understand intraspecific variation in Squatina sp., these differences were not considered diagnostic. Tooth rows arranged similar to those described for S. guggenheim and S. occulta , in 18 rows on upper jaw and 20 rows on lower (tooth formula 9-9/10- 10). Tooth morphology very similar to that described for other species. Dermal denticles over trunk, tail, pectoral and pelvic fins similar to other species, with rounded to rhomboidal basal plates and crowns projecting posteriorly, with four ridges along entire anterior surface ( Fig. 34 ). Dorsal midline denticles presenting basal plate slightly larger (1.5 diameter of basal plate of other dorsal denticles), but crown morphology similar to dorsal denticles, from origin of tail to first dorsal fin origin (similar to S. occulta and S. argentina ). Enlarged, conical and morphologically distinct denticles over dorsal surface of head positioned in three groups similar to S. argentina ; however, a pair of dermal denticles present between spiracles with slightly enlarged basal plates (approximately 1.5 diameter of other denticles) and crown also similar to other dorsal denticles in size and with four ridges, but somewhat more conical in shape ( Figures 34 b, c). This pattern was not observed in any specimen of the other species of Southwestern Atlantic Squatina , leading us to propose this character as a diagnostic feature.

Pectoral and pelvic fins of specimen MNRJ 30190 ( Tab. 8 ) with similar number of radials as other examined Squatina species; however, a higher number of total vertebrae, mainly precaudal diplospondylous vertebrae, was observed in comparison to other Southwestern Atlantic species. Squatina sp. has 150 total vertebral centra (50 monospondylous vertebrae, 67 precaudal diplospondylous vertebrae, and 33 caudal diplospondylous vertebrae). Monospondylous and precaudal diplospondylous vertebrae, and also total vertebrae, are higher than any maximum value obtained for other Squatina species treated here (meristic data of other species in Tabs. 2 , 4 and 6 ). Again, more specimens of this form are needed to confirm these vertebral characters.

Skeletal morphology (analyzed from radiographs) is also similar to other species. The basihyal of Squatina sp., however, has an outline more similar to S. guggenheim , with an anterior segment not projecting anteriorly as far as in S. occulta . However, as noted for S. argentina , radiographs may slightly distort the general outline of some structures.

An incision already present on specimen MNRJ 30190 allowed us to analyze the internal abdominal cavity. The reproductive tract of this specimen has two functional ovaries as in S. argentina (Vooren and da Silva, 1991; Vooren and Klippel, 2005), differently from S. guggenheim and S. occulta , which have only the left ovary functional. Although MNRJ 30190 is an immature specimen (690 mm TL) and the ovaries are not completely developed, it was possible to verify that the ovarian sac is already present with several oocytes inside ( Figs. 36 a, b).

Character MNRJ 30190 Propterygial radials 3

Mesopterygial radials 11 Matapterygial radials 24 Pelvic radials 23 Monospondylous vertebrae 50 Precaudal diplospondylous vertebrae 67 Caudal diplospondylous vertebrae 33 Total vertebrae 150 Upper tooth rows (rigth side) 9

Upper tooth rows (left side) 9

Lower tooth rows (rigth side) 10 Lower tooth rows (left side) 10

Figures

FIGURE 32. Specimen of Squatina sp. in dorsal (A) and ventral (B) views (MNRJ 30190, juvenile female, continental shelf of Bahia state, Brazil, 690 mm TL).

FIGURE 33. Morphological details of Squatina sp. (MNRJ 30190). A) Dorsal view of head. B) Ventral view of head and pectoral region. C) Ventral view of pelvic fins. D) Dorsal view of anterior region of trunk, pectoral and pelvic fins. E) Lateral view of dorsal fins. F) Lateral view of caudal fin. Scale bar = 50 mm.

FIGURE 34. Dermal denticles of Squatina sp. (MNRJ 30190: A – C) from posterior region of dorsal midline (A). Dermal denticles from interspiracular region, near right (B) and left spiracle (C). Dermal denticles from interspiracular region of Squatina argentina (MCP 3754), showing lack of enlarged denticles (D). Single enlarged dermal denticles on interspiracular region in (E) Squatina occulta (NUPEC 1227) and (F) Squatina guggenheim (MZUSP 110869). Figures A, B and D, anterior to left; figures C, E and F, anterior to top.

FIGURE 35. Morphological details of head skeleton from radiograph of Squatina sp. (MNRJ 30190), in dorsoventral view. Abbreviations are as in Figs. 41, 45 and 47.

FIGURE 36. Morphology of female reproductive system of Squatina sp. showing right (A) and left (B) functional ovaries, while Squatina guggenheim and Squatina occulta present only left ovary functional (D and F, respectively), and right ovary reduced (C and E, respectively). Abbreviations: lov, left ovary; lv, liver; rov, right ovary; sch, stomach; spv, spiral valve. Scale bar = 10 mm. ”

Tables

TABLE 8. Meristic data for specimen of Squatina sp. (MNRJ 30190).

TABLE 7. Measurements for specimen of Squatina sp.	(MNRJ 30190).
Morphometric character MNRJ 30190	Morphometric character	MNRJ 30190
mm % TL	(cont.)	mm % TL
Total length (TL) 690.0	Width at pectoral origins	100.9 14.6
Pre-caudal length 591.0 85.7	Trunk width	114.7 16.6
Pre-dorsal length 441.0 63.9	Tail width	79.3 11.5
Pre-pectoral length 123.6 17.9	Tail height	37.0 5.4
Pre-pelvic length 266.0 38.6	Pectoral-fin length	241.0 34.9
Pre-branchial length 102.5 14.9	Pectoral-fin anterior margin	205.0 29.7
Pre-spiracular length 56.7 8.2	Pectoral-fin base length	74.1 10.7
Pre-ocular length 33.0 4.8	Pectoral-fin width	125.4 18.2
Pre-orbital length 24.4 3.5	Pectoral-fin inner margin	128.0 18.5
Head width 116.9 16.9	Pelvic-fin length	182.0 26.4
Orbital head width 93.9 13.6	Pelvic-fin width	103.5 15.0
Spiracular head width 128.1 18.6	Pelvic-fin inner margin	79.0 11.4
Mouth width 89.0 12.9	First dorsal-fin base length	26.1 3.8
Head height 46.6 6.8	First dorsal-fin anterior margin	61.8 8.9
Interorbital distance 56.4 8.2	First dorsal-fin height	39.9 5.8
Eye length 14.2 2.1	First dorsal-fin inner margin	15.4 2.2
Eye width 10.1 1.5	Second dorsal-fin base length	25.8 3.7
Eye-spiracle distance 20.0 2.9	Second dorsal-fin anterior margin	56.7 8.2
Internarial distance 42.8 6.2	Second dorsal-fin height	36.7 5.3
Interspiracular distance 50.3 7.3	Second dorsal-fin inner margin	18.6 2.7
Spiracle length 14.0 2.0	Dorsal caudal-fin margin	91.0 13.2
Intergill width 56.0 8.1	Preventral caudal-fin margin	118.6 17.2
Intergill length 16.1 2.3	Caudal-fin height	97.4 14.1
Interdorsal distance 45.4 6.6	Clasper inner length	0.0 0.0
Dorsal-caudal distance 48.5 7.0	Clasper outer length	0.0 0.0
Pectoral-pelvic distance 70.1 10.2	Clasper base width	0.0 0.0
Pelvic (origin)-caudal distance 338.0 49.0	Snout-cloacal length	324.0 47.0
Pelvic-caudal distance 231.0 33.5	Cloacal-caudal length	372.0 53.9