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

description: 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
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 45-49, DOI: 10.11646/zootaxa.3695.1.1, http://zenodo.org/record/284327