Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

BRACCINI J. M

CONCHA F

EBERT D. A

Fernanda Rocha

GOMES U. L

HUBBS C. L

ISHIYAMA R

MABRAGAÑA E

Maria Cristina Oddone

McEACHRAN J. D

ODDONE M. C

Otto B. F Gadig

PARAGÓ C

SAN MARTÍN M. J

SOKAL R. R

TEMPLEMAN W

TRELOAR M. A

Brazilian Journal of Oceanography

Crossref

Egg capsules of the little skate, Psammobatis extenta (Garman, 1913) (Chondrichthyes, Rajidae)

Directory of Open Access Journals

Rocha, Fernanda

Oddone, Maria Cristina

Gadig, Otto B. F

Cadernos Espinosanos (E-Journal)

NOTE BRAZILIAN JOURNAL OF OCEANOGRAPHY, 58(3):251-254, 2010 EGG CAPSULES OF THE LITTLE SKATE, Psammobatis extenta (GARMAN, 1913) (CHONDRICHTHYES, RAJIDAE)  Fernanda Rocha1,*, Maria Cristina Oddone2,3  and Otto B. F. Gadig1,4  1Universidade Estadual Paulista “Julio de Mesquita Filho” – UNESP  Campus Experimental do Litoral Paulista, Laboratório de Elasmobrânquios (Praça Infante Dom Henrique s/n° 11330-900, São Vicente, SP, Brasil)  2Universidade Federal do Rio Grande - Departamento de Oceanografia Laboratório de Elasmobrânquios e Aves Marinhas (Caixa Postal 474, 96201-900 Rio Grande, RS, Brasil)  3e-mail: cristina_oddone@yahoo.com  4e-mail: gadig@clp.unesp.br  *Corresponding author: rochaf_bio@yahoo.com.br   The elasmobranch Rajidae family, known usually as skates, is the most numerous group among cartilaginous fishes, having almost 245 species with very conservative morphology (EBERT and COMPAGNO, 2007). Elasmobranch egg capsules are widely recognised as important in species identification and provide relevant information concerning their reproductive biology (ODDONE et al., 2004). The genus Psammobatis GÜNTHER, 1870 comprises eight species, four of them recorded in Brazil (PARAGÓ, 2001): P. extenta (GARMAN, 1913), P. rutrum JORDAN, 1890, P. bergi MARINI, 1932, and P. lentiginosa (BIGELOW and SCHROEDER, 1953). Psammobatis extenta, the little skate, is endemic to the continental shelf of the western South Atlantic, ranging from Cabo Frio, Rio de Janeiro, Brazil (22°56’S) to Patagonia, Argentina (~ 45°S) (PARAGÓ, 2001). Recent studies of P. extenta have focused mainly on its reproduction, morphology and feeding habits (BRACCINI and PEREZ, 2005; BRACCINI and CHIARAMONTE, 2002a; 2002b) and detailed information concerning its egg capsules is lacking. Only the egg capsules of P. scobina (PHILIPPI, 1857), from the Southeastern Pacific, have been accurately described (CONCHA et al., 2009); short descriptions of the egg capsules of P. rudis, P. normani and P. bergi have been presented with their reproductive biology (MABRAGAÑA and COUSSEAU, 2004 and SAN MARTÍN et al., 2005). The present study describes the egg capsules of Psammobatis extenta, a small common rajid species of the western South Atlantic.   Sixty-one egg capsules were removed directly from the 35 female Psammobatis extenta oviduct, thus avoiding species misidentification. The females were collected by bottom trawlers on the São Paulo continental shelf, at 30 to 50 m depths (between 24°12’S; 46°04’ W and 24°08’S; 46°50’W), during 2002, except in autumn. The general morphology, color, texture, presence and number of eggs, presence and position of attachment fibrils, presence and shape of velum and keel and finally, presence, position and shape of ventilation fissures were all recorded. The measurements taken were: capsule length (without horns), maximum width, anterior and posterior horn lengths, capsule height, and thickness and width of lateral keel. Both the terminology and morphometrics follow TEMPLEMAN (1982), ODDONE et al. (2004) and TREOLAR et al. (2006). Only fully developed capsules were used in the calculations made and the terms ‘anterior’/‘posterior’ and ‘dorsal’/‘ventral’ refer to the position of the egg capsules in the female oviduct (TEMPLEMAN, 1982). Capsules were fixed in formalin and preserved in 70% ethanol. The total length of the females was measured from the tip of the snout to the tip of the tail. Differences between anterior and posterior horn lengths and between right and left egg capsules were verified with Student´s t-test and the relationship between the females´ total length and the body length of the capsules was investigated by linear regression (SOKAL and ROHLF, 1995).  The capsule measurements are presented in Table 1. Only one egg capsule was found in each female’s oviduct and just one egg was found per capsule. Almost 75% of the gravid females had capsules in both oviducts and when only one capsule was present, it was in the left oviduct (except for one female, which had developing horns on the right shell gland). The fully developed egg capsules are rectangular, with a horny process on each corner and a brownish copper in color (Fig. 1). The capsule walls are symmetrically convex, with the highest point situated centrally. Both capsule walls present a                                    delicate longitudinal striation although they are rather smooth to the touch. The capsules have uniform keeled lateral margins (of less than 5% of the capsule´s width). The anterior horns are of three-quarters of the capsule´s length, while the posterior ones are of the length of the capsule. The horns, the keel and the ventral wall are covered by sticky attachment fibrils, which are pale yellow with gold bright in color. They were linked to the capsule by three adhesion plates of 2.08 mm (± 0.26 mm) in length, at the base of each horn and in the middle of the keel (Fig. 2). Four ventilation fissures were present, one in each horn. The anterior ventilation fissures had straight borders while the posterior ones began straight but changed to wavy (Fig. 3). The anterior ventilation fissures began in the middle of the horn, having half its length. The posterior ventilation fissures began between one-third and one-fourth of the posterior horns length, having two-thirds of their length. Only the posterior end of the capsule displays a velum, whose length was around 15% of the capsule´s. The general morphology of the P. extenta egg capsule was extremely conservative among females. As a result, no significant results were obtained in the linear regression study between total length of the female and the capsule length (P > 0.01), nor in the t-test between right and left egg capsule dimensions and measurements (P > 0.01). The proportion of the females carrying egg capsules did not increased with female total length (Fig. 4).   Table 1. Measurements (mm) of the Psammobatis extenta egg capsule.    Mean SD range n Capsule length 26.28 0.74 27.45 - 24.80 22 Max. width 18.45 0.69 19.75 - 16.85 23 Anterior horn length 20.32 3.59 27.70 - 10.30 23 Posterior horn length 25.88 4.91 35.50 - 22.95 19 Capsule heigth 7.30 0.92 8.30 - 5.10 23 Keel thickness 0.83 0.25 2.05 - 0.40 26 Keel width 0.78 0.22 1.40 - 0.30 26            Fig. 1. The fully developed egg capsule of Psammobatis extenta in upper view (above) and lateral view (below). AH= anterior horns, PH= posterior horns, V= velum, AF= adhesion fibrils. Left side of the picture corresponds to the anterior end of the egg capsule. Black bar represents 10 mm.       Fig. 2. Adhesion plates of the attachment fibrils of the egg capsule of Psammobatis extenta in the middle of the keel. White bar represents 0.5 mm.  252                     BRAZILIAN JOURNAL OF OCEANOGRAPHY, 58(3), 2010                                 Fig. 3. Ventilation fissure of the posterior horn of the egg capsule of Psammobatis extenta. Right side of picture corresponds to the posterior end of the horn, near to the tip. Black bar represents 0.25 mm.   0%25%50%75%100%Egg-bearing females (%)Total length (mm)  Fig. 4. Proportion of egg-bearing females and female total length (mm).  Just as with other rajids, P. extenta showed single oviparity and the majority of the gravid females had capsules in both oviducts (e.g. BRACCINI and CHIARAMONTE, 2002a and MABRAGAÑA and COUSSEAU, 2004). When there was only one capsule, it was in the left oviduct, showing that the right capsule is deposited first as observed by many authors in other rajid species (e.g. McEACHRAN, 1970; BRACCINI and CHIARAMONTE, 2002a and EBERT, 2005). In addition to the measurements, observations on rajid egg capsule features distinguish among species by such characters as degree of development of the fibrils’ mass and the location of the ventilation fissures (HUBBS and ISHIYAMA, 1958 and ISHIYAMA, 1958). As regards size, P. extenta capsules are smaller than the other rajid capsules already described, which could be a supporting character for identification. As in this study, SAN MARTIN et al. (2005) found no relationship for P. bergi between female total length and the proportion of egg-bearing females such as was found for P. extenta by BRACCINI and CHIARAMONTE (2002a). Nor did those authors detect any significant difference in morphology between egg capsules from the right and left oviducts. The capsule of P. extenta has only the posterior velum whereas the capsules of P. scobina, P. rudis and P. normani have both anterior and posterior vela (MABRAGAÑA and COUSSEAU, 2004 and CONCHA et al., 2009). Psammobatis scobina and P. rudis had longer posterior than anterior horns, while in P. normani they were of the same length                         ROCHA ET AL.: EGG CAPSULES OF Psammobatis extenta                                           253                                     (MABRAGAÑA and COUSSEAU, 2004 and CONCHA et al., 2009) exactly as in P. extenta. Only McEACHRAN (1970) has detailed the ventilation fissures of skates´ egg capsules in Raja garmani, but this feature is well known and has been studied in Scyliorhinidae sharks (e.g. GOMES and CARVALHO, 1995). Those fissures are responsible for a great part of the water circulation inside the egg capsule. EBERT and DAVIS (2007) state that the fibrous covering and the attachment fibrils of egg capsules vary a lot among skate species, which, according to ODDONE et al. (2004), may be closely related to the way in which each species attaches their egg capsules to the sea bottom. In P. scobina, the attachment fibrils had only two attachment points (CONCHA et al., 2009), while P. extenta had three, just like Bathyraja kincaidii, R. rhina and R. stellulata (EBERT and DAVIS, 2007), but the authors give no details as to their adhesion to the capsule, whether it occurred in plates.   ACKNOWLEDGEMENTS   The authors are sincerely grateful to: Fernando José Zara (UNESP, Campus Experimental do Litoral Paulista, São Vicente) for assistance in preparing the pictures; Patrícia Charvet (Museu Paraense Emílio Goeldi) for her suggestions, and João Pedro Barreiros (Universidade dos Açores, Portugal) for the English revision. They also wish to thank FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo) and CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico) for their respective financial support of FR and OBFG.   REFERENCES  BRACCINI, J. M.; CHIARAMONTE, G. E. Reproductive biology of Psammobatis extenta. J. Fish Biol., v. 61, p. 272-288, 2002a. BRACCINI, J. M.; CHIARAMONTE, G. E. Intraspecific variation in the external morphology of the sand skate. J. Fish Biol., v. 61, p. 959-972, 2002b. BRACCINI, J. M.; PEREZ, J. E. Feeding habits of the sandskate Psammobatis extenta (Garman, 1913): sources of variation in dietary composition. Mar. Freshwater Res., v. 56, p. 395-403, 2005. CONCHA, F.; HERNÁNDEZ, S.; ODDONE, M. C. Egg capsules of the raspthorn sandskate, Psammobatis scobina (Philippi, 1857) (Rajiformes, Rajidae). Rev. Biol. Mar. Oceanog. v. 44, n. 1, p. 253-256, 2009.       EBERT, D. A.; COMPAGNO, L. J. V. Biodiversity and systematics of skates (Chondrichthyes: Rajiformes: Rajoidei). Environ. Biol. Fish., DOI 10.1007/s10641-007-9247-0, 2007. EBERT, D. A.; DAVIS, C. D. Descriptions of skate egg cases (Chondrichthyes: Rajiformes: Rajoidei) from the eastern North Pacific. Zootaxa, v. 1393, p. 1-18, 2007. EBERT, D. A. Reproductive biology of skates, Bathyraja (Ishiyama), along the eastern Bering Sea continental slope. J. Fish Biol., v. 66, p. 618-649, 2005. GOMES, U. L.; CARVALHO, M. R. Egg capsules of Shroederichthyes tenuis and Scyliorhinus haeckelli (Chondrichthyes: Scyliorhinidae). Copeia, v. 1995, p. 232-236, 1995. HUBBS, C. L.; ISHIYAMA, R. Methods for the taxonomic study and description of skates (Rajidae). Copeia, n. 3, p. 483-491, 1968. ISHIYAMA, R. Observations on the eggs-capsules of skates of the family Rajidae, found in Japan and its adjacent waters. Bull. Mus. Comparat. Zool. Harvard College, v. 118, n. 1, p. 1-24, 1958. MABRAGAÑA, E.; COUSSEAU, M. B. Reproductive biology of two sympatric skates in the south-west Atlantic: Psammobatis rudis and Psammobatis normani. J. Fish Biol., v. 65, p. 559-573, 2004. McEACHRAN, J. D. Egg capsules and reproductive biology of the skate Raja garmani (Pisces: Rajidae). Copeia, v. 1970, p. 197-199, 1970. ODDONE, M. C.; MARÇAL, A. S.; VOOREN, C. M. Egg capsules of Atlantoraja cyclophora (Regan, 1903) and A. plantana (Günterm, 1880) (Pisces, Elasmobranchii, Rajidae). Zootaxa, v. 426, n. 1-4, 2004. PARAGÓ, C. Contribuição à taxonomia do gênero Psammobatis Günther, 1870 (Chondrichthyes, Rajidae): Caracterização das espécies do subgênero I de McEachran (1983) com base em padrões de coloração e espinulação. 2001. 52p. Dissertação (Mestrado). Universidade Federal do Rio de Janeiro, UFRJ, Rio de Janeiro. SAN MARTÍN, M. J.; PEREZ, J. E.; CHIARAMONTE, G. E. Reproductive biology of the South West Atlantic marbled sand skate Psammobatis bergi Marini, 1932 (Elasmobranchii, Rajidae). J. Appl. Ichthyol., v. 21, p. 504-510, 2005. SOKAL, R. R.; ROHLF, F. J. Biometry: the principles and practices of statistics in biological research. W. H. Freeman, San Francisco, 1995. 776p. TEMPLEMAN, W. Development, occurrence and characteristics of egg capsules of Raja radiata in the NW Atlantic. J. NW Atl. Fish. Sci., v. 3, p. 47-56, 1982. TRELOAR, M. A.; LAURENSON, L. J. B.; STEVENS, J. D. Descriptions of rajid egg cases from southeastern Australian waters. Zootaxa, v. 1231, p. 53-68, 2006.   (Manuscript received 28 November 2009; revised 26 April 2010; accepted 06 May 2010)    254                      BRAZILIAN JOURNAL OF OCEANOGRAPHY, 58(3), 2010  

English

Submitted by Denielton Guimarães (denielton@gmail.com) on 2011-09-22T20:19:50Z
No. of bitstreams: 1
Egg capsules of the little skate, Psammobatis extenta (Garman, 1913) (Chondrichthyes, Rajidae)..PDF: 619417 bytes, checksum: 0ad5d44c24ad4385de2c41ec7749c002 (MD5)Approved for entry into archive by Barbara Milbrath(barbaramilbrath@yahoo.com.br) on 2011-09-24T03:16:35Z (GMT) No. of bitstreams: 1
Egg capsules of the little skate, Psammobatis extenta (Garman, 1913) (Chondrichthyes, Rajidae)..PDF: 619417 bytes, checksum: 0ad5d44c24ad4385de2c41ec7749c002 (MD5)Made available in DSpace on 2011-09-24T03:16:35Z (GMT). No. of bitstreams: 1
Egg capsules of the little skate, Psammobatis extenta (Garman, 1913) (Chondrichthyes, Rajidae)..PDF: 619417 bytes, checksum: 0ad5d44c24ad4385de2c41ec7749c002 (MD5)
  Previous issue date: 201

Gadig, Otto Bismarck Fazzano

LAReferencia - Red Federada de Repositorios Institucionales de Publicaciones Científicas Latinoamericanas

Egg capsules of the little skate, Psammobatis extenta  (GARMAN, 1913) (Chondrichthyes, Rajidae)

Egg capsules of the little skate, Psammobatis extenta (GARMAN, 1913) (Chondrichthyes, Rajidae)

Abstract

Similar works

Full text

Available Versions

Crossref

Directory of Open Access Journals

Cadernos Espinosanos (E-Journal)

LAReferencia - Red Federada de Repositorios Institucionales de Publicaciones Científicas Latinoamericanas

RI FURG

LAReferencia - Red Federada de Repositorios Institucionales de Publicaciones Científicas Latinoamericanas

Acervo Digital da Unesp