Hindawi Publishing Corporation Journal of Marine Biology Volume 2011, Article ID 842821, 18 pages doi:10.1155/2011/842821

Research Article Sexually Dimorphic Morphological Characters in Five North Atlantic Deepwater Skates (: )

Alexei M. Orlov1 and Charles F. Cotton2

1 Russian Federal Research Institute of Fisheries and Oceanography (VNIRO), 17 V. Krasnoselskaya, Moscow, 107140, Russia 2 Department of Fisheries Science, Virginia Institute of Marine Science, P.O. Box 1346, Gloucester Point, VA 23062, USA

Correspondence should be addressed to Alexei M. Orlov, [email protected]

Received 16 March 2011; Accepted 9 May 2011

Academic Editor: Jakov Dulciˇ c´

Copyright © 2011 A. M. Orlov and C. F. Cotton. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Skates exhibit a variety of manifestations of sexual dimorphism. However, this phenomenon has been poorly documented in deepwater species. New data on the sexual dimorphism of five species of deepwater skates from the North Atlantic Ocean are presented: Amblyraja jenseni, Bathyraja pallida, Bathyraja richardsoni, Rajella bigelowi, and R. kukujevi. These skates exhibit sexual dimorphism most frequently in interorbital width, disc length and width, length of the third gill slit, horizontal diameter of the orbit, length of the fifth gill slit, space between the first and fifth gill slits, length of the second dorsal fin base, mouth width, length and width of each lobe of the nasal curtain, distance from the snout to the center of anus, distance from the snout tip to the point of maximum disc width, length of the lateral fold, length of the orbit + spiracle (measured together), tail height at the pelvic fin tips, and the number of median thorns.

1. Introduction the phenomenon has been poorly documented in deepwater species. This study presents new data on sexually dimorphic Skates (Rajoidei) comprise an important component of shelf morphological characters of five deepwater species and continental slope benthic communities of the world’s from the North Atlantic Ocean: Jensen’s skate, Amblyraja oceans. They are major consumers of cephalopods, deca- jenseni [28]; pale ray, Bathyraja pallida [29]; Richardson’s pods, and fishes, often utilizing the same food resources as ray, Bathyraja richardsoni [30]; Bigelow’s ray, Rajella bigelowi the apex predators, such as sea birds, marine mammals, and [31]; Mid-Atlantic skate, R. kukujevi [32]. sharks [1]. Skates, like all chondrichthyan fishes, exhibit sex- ual dimorphism in the structure of the pelvic fins, which in 2. Materials and Methods males are modified to act as copulatory organs, or claspers [2]. Also, mature male skates have alar thorns on the edges Our comparative analysis of skate morphology was based on of the disc, which help to grasp the female during copulation the measurement of 45–47 morphometric and 2–15 meristic [3–5]. In many species sexual differences have been reported characters, according to protocols used in recent years [33– in length, body mass, size and age of sexual maturity, other 35]. For some meristic characters (preorbital thorns, post- external morphological features, and diet [3, 5–16]. Mature orbital thorns, orbital thorns, interspiracular thorns, and females and males of several skate species exhibit differences scapular thorns) we observed differences in thorn counts in the form and length of the teeth [3, 15, 17–23]. In one on the left and right side of each specimen. Therefore, species, differences were observed in the shape and size we present maximum, minimum, and mean values for of the shoulder and pelvic girdle [24]. Sexual differences one side for each character. The material examined by in size and shape of the olfactory and electrical organs the authors during 2005–2006 consisted of the majority have also been found in some skates [3, 25–27]. Even with of specimens of five deepwater skate species available from this variety of manifestations of sexual dimorphism in skates, ichthyological collections worldwide (MCZ-Museum of 2 Journal of Marine Biology

Comparative Zoology, Harvard University, Cambridge, Mas- 3. Results and Discussion sachusetts, USA; ZMUB-Zoological Museum, University of Bergen, Bergen, Norway; USNM-National Museum of Amblyraja jenseni was described in the middle of the past Natural History, Smithsonian Institute, Washington DC, century [28] and since then, several records of this skate USA; VIMS-Virginia Institute of Marine Science, Gloucester have been reported from the North Atlantic [43–47]. Until Point, Virginia, USA; NMSZ-National Museum of Scotland, recently, morphometric and meristic data were limited to Edinburgh, Scotland; BMNH-British Museum of Natural three specimens [28, 36, 39]. Although a recent study [35] History, London, Great Britain; NMHN-Museum National considerably expanded the knowledge of morphological d’Histoire Naturelle, Paris, France; ZISP-Zoological Institute, features of A. jenseni, information about sexual dimorphism Sankt-Peterburg, Russia). All measurements were conducted of this species, until now, was absent. ff in accordance with conventional procedures [3, 36–38]. The Our results show that the greatest di erences in male and following juvenile, adolescent, and mature specimens were female A. jenseni are found in the disc length, horizontal di- examined (the numbers of females and males, resp., of each ameter of the orbit, height of the tail at the pelvic fin tips, species are indicated in parenthesis). length of the third gill slit, space between the fifth gill slits, distances from the center of the anus to the first and second Amblyraja jenseni (7/6)—MCZ 37899, 38354, 55011, dorsal fins (Table 1). 138020-1, 138020-2, 155628; ZMUB 19529, 19462, 19463; Bathyraja pallida was described in the second half of VIMS 11757; USNM 35592, 23483, 33457. The USNM speci- the past century [29]. Although there have been eight sub- mens were not examined in this study but the morphological sequent specimens collected [34, 45, 48–50], morphome- data were taken from Bigelow and Schroeder [28, 36, 39]. tric and meristic data are limited to two specimens, and Bathyraja pallida (3/7)—ZMUB 19465, VIMS 11577, these accompanied the original description of the species VIMS 11758, NMSZ 2000.130.462, NMSZ 2000.130.80, [29]. A recent publication [35] contributed to the existing BMNH 1967.2.13.2, BMNH 1985.11.14.1, BMNH morphological data available for this species; however, that 1985.11.14.2, BMNH 1985.11.14.3, BMNH 1985.11.14.4. study did not include information about sexual dimorphism. Bathyraja richardsoni (14/13)—BMNH 1999.2.2.1, Furthermore, these data were based on the examination of BMNH 1999.2.2.2, BMNH 1999.2.2.3, BMNH 1999.2.2.4, only three specimens. BMNH 1999.10.1.1, BMNH 1999.10.1.2, NMHN 1999- Maximum differences between male and female B. 1156, NMSZ 2000.130.260, ZMUB 19522-1, ZMUB pallida were found in the following characters (Table 2): in- 19522-2, ZMUB 19522-3, ZMUB 19514-1, ZMUB 19514-2, terorbital width, interspiracular width, height of the first ZMUB 19514-3, ZMUB 19514-4, ZMUB 19476, ZMUB dorsal fin, lengths of the first and second dorsal fin bases, 17600, ZMUB 19448, ZMUB 19464, ZMUB 19364, ZMUB tail height at the pelvic fin tips, mouth width, nasal curtain 19446, ZMUB 19528, ZMUB 19535, VIMS 11756. length and width, width of each lobe of the nasal curtain, Rajella bigelowi (8/10)—NMHN 1988-361, NMHN length of first gill slit, space between the first gill slits and the 1987-482, NMHN 1999-1162; ZMUB 18406, ZMUB 18405; fifth gill slits, distance from the snout tip to the center of the MCZ 55316(A), MCZ 55316(B), MCZ 55316(C), MCZ anus, distance from the center of the anus to the tail tip, and 58444, MCZ 55314, MCZ 158964, MCZ 57327, VIMS 5562 the number of teeth in the lower jaw. n = ( 3), VIMS 8444, VIMS 3347, VIMS 5424. The morphological and meristic characters of Bathyraja Rajella kukujevi (2/6)—ZISP 46195, ZMUB 15709, richardsoni have been examined more thoroughly than most NMHN 1998-0727, NMHN 1999-1165, NMHN 1996-1157, other species in our study. Information on the morphology NMHN 1996-1153, NMHN 1996-235, NMHN 1996-1154. of 16 mature individuals of this species has been published in Furthermore, for our comparative analyses of B. richard- several early papers [30, 40, 51, 52]. However, these studies soni and A. jenseni, we also included published data [28, 30, omitted many of the morphometric and meristic characters 36, 39, 40]. We used conventional abbreviations to denote used in our study. More recently [34], a similar measurement museum collections [41, 42]. scheme on four advanced embryos of this species was used, Because of the small number of deepwater skates avail- and the same measurement scheme was used on several able in ichthyological collections we had an opportunity specimens caught on the Mid-Atlantic ridge during the to examine only 13 specimens of A. jenseni,10specimens MAR-ECO expedition (www.mar-eco.no), as well as material of B. pallida,27specimensofB. richardsoni,12specimens from the BMNH and MNHN collections [35]. Nevertheless, of R. bigelowi, and eight specimens of R. kukujevi. Since none of these prior studies offer information about sexual sample size was too small, the statistical significance of dimorphism of B. richardsoni. the compared material was not evaluated using standard Our results show B. richardsoni to be sexually dimorphic statistical tests. Instead, we evaluated the significance of in the following characters (Table 3): disc width, disc length, variation in morphological characters between males and horizontal diameter of the orbit, length of the orbit + spiracle females by comparing the mean (M) and standard error (m) (measured together), tail width at the pelvic fin tips, length for each set of measurements. If the standard errors of the of the lateral fold, mouth width, lengths of the third and fifth means did not overlap (M ± m) between males and females, gill slits, distance from the snout tip to the center of the anus, such differences were considered significant. distance from the snout tip to the line of maximum disk Journal of Marine Biology 3 m 0.79 0.84 0.85 1.22 1.81 0.65 0.35 0.91 0.52 0.10 0.20 0.07 0.08 0.41 0.51 0.14 0.75 0.10 0.18 0.29 0.81 0.16 0.18 0.34 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± erences are given in bold, number of ff erent areas of the North Atlantic (significant di ff m Min Max Mean Min Max Mean 0.60 119.8 632.0 351.5 51.9 56.8 55.1 0.31 32.1 174.0 89.60.19 23.6 10.3 15.8 115.0 14.2 74.4 10.2 15.8 11.7 1.621.32 107.0 77.9 345.0 309.0 235.6 212.4 30.5 39.6 27.8 34.5 34.2 30.2 0.71 37.1 149.0 88.7 12.6 16.9 14.5 1.51 156.5 837.0 466.4 70.2 75.5 73.3 0.58 27.9 150.0 84.7 12.3 14.5 13.0 0.06 6.8 23.0 15.9 2.0 2.5 2.3 0.52 9.2 22.0 16.1 1.8 4.7 3.1 0.44 0.0 3.10.06 1.30.12 3.0 4.2 0.0 11.0 14.3 1.1 7.2 0.4 9.1 0.8 1.1 1.3 1.6 1.0 1.3 0.26 13.80.33 77.2 16.2 47.4 60.0 6.20.49 39.9 11.1 8.70.18 4.8 7.5 30.0 8.1 7.2 31.7 5.8 18.1 2.2 21.5 5.5 2.8 3.3 3.6 3.1 0.460.25 3.8 3.3 25.6 30.4 13.2 13.8 1.7 1.5 2.3 2.7 2.0 2.0 0.72 29.9 115.0 66.8 7.4 11.1 9.7 0.160.27 11.2 8.8 48.9 53.0 28.4 29.8 3.9 3.3 5.0 5.2 4.6 4.5 0.28 10.9 25.0 18.0 2.2 4.0 2.7 0.16 5.6 37.3 20.4 2.5 3.8 3.1 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± Females (7) Males (6) standard error). = Absolute % TL Absolute % TL 4.9 13.5 8.5 0.9 1.6 1.3 4.2 9.8 7.0 0.9 1.2 1.0 0.0 29.0 6.3 0.0 3.4 0.9 8.9 25.3 17.0 2.4 2.7 2.5 11.4 30.3 21.1 2.7 3.6 3.1 40.8 110.0 75.8 10.314.1 12.0 45.0 11.1 23.9 2.4 5.3 3.5 61.2 157.0 103.3 14.0 16.6 15.2 27.8 68.1 46.1 6.0 7.8 6.8 20.9 56.3 42.2 5.3 6.9 6.2 Min Max Mean Min Max Mean 10.6 40.0 27.0 2.5 5.8 4.2 143.0 337.0 243.0 31.6 38.8 36.4 105.3 281.0 205.3 26.4 33.3 30.4 207.0 593.0 390.5 55.7 60.0 57.1 1: Morphometrics and meristics of male and female Jensen’s ray Amblyraja jenseni from di base lengthbase length 17.8 19.7 47.0 44.6 30.7 32.3 4.3 4.2 5.4 5.8 4.7 5.0 preoral 54.9 135.0 92.9 11.6 16.3 13.6 width at D1 lateral fold width at length height at height at D1 prenasal 38.7 80.3 65.0 7.5 10.6 9.7 TL, mmDisc width 369.0 264.0 1065.0 795.0 686.6 510.4 69.5 81.3 74.2 223.0 1113.0 635.0 Character origin length V-tips Orbit, horizontal diameter Mouth width 45.5 157.0 93.3 11.9 15.9 13.3 V-tips origin D1, height 6.0 42.0 17.3 1.5 4.9 2.3 Interspiracular width Tail, postdorsal length Spiracle length 11.2 34.4 19.6 2.3 3.4 3.0 Head length, ventrally Snout length, preorbital C, base length 13.1 28.3 20.1 2.4 3.6 3.0 Interorbital width Interdorsal space Orbit + spiracle length D2, height 5.6 28.0 14.4 1.3 3.3 2.0 Table specimens examined are shown in parentheses, m 4 Journal of Marine Biology m 2.52 1.39 1.10 3.51 0.63 1.43 0.81 1.65 1.63 1.47 0.36 0.07 0.09 0.56 0.41 0.12 0.85 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 4.51 0.32 0.20 0.24 ± ± ± ± m Min Max Mean Min Max Mean 0.52 74.9 349.0 180.8 17.1 33.6 29.3 0.59 104.0 390.0 246.4 30.2 38.5 34.9 0.74 31.2 170.0 87.2 10.5 16.4 13.4 0.62 42.10.540.36 225.0 23.9 54.0 143.0 135.1 229.0 78.2 16.3 138.3 24.8 10.7 20.4 16.7 15.2 20.6 12.4 19.0 1.021.44 114.8 105.0 678.0 400.0 359.1 255.8 51.1 31.4 60.9 39.7 54.8 36.5 0.81 108.2 475.0 270.5 38.1 48.5 43.7 0.22 28.5 133.0 76.5 11.1 13.7 12.3 0.05 3.6 22.5 12.1 1.6 2.0 1.7 0.02 2.9 18.5 9.6 1.3 1.7 1.4 0.350.24 18.0 6.8 65.3 29.0 36.3 18.5 3.4 1.9 6.7 4.2 5.4 2.6 0.34 21.80.08 115.0 2.2 70.5 16.9 7.8 8.2 12.1 9.7 0.9 1.5 1.2 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 1: Continued. Table Females (7) Males (6) 3.00 89 103 94.0 0.240.200.24 1 1 3 1 2 2.0 2 1.8 1.4 ± ± ± ± Absolute % TL Absolute % TL 121.8 121.6 121.6 na na na na na na 20.5 240.0 116.9 7.6 23.2 13.5 5.2 14.2 8.7 1.3 1.4 1.3 5.4 16.8 9.9 1.3 1.6 1.5 74.6 206.0 131.5 18.1 20.2 19.3 10.030.4 23.6 107.0 13.8 65.7 1.5 8.2 2.8 10.1 2.1 9.4 68.7 186.0 137.5 17.5 22.1 20.2 20.5 56.4 34.6 3.7 5.6 5.1 55.7 123.0 81.0 11.5 15.1 12.5 Min Max Mean Min Max Mean 52.3 139.0 104.9 13.1 18.1 15.6 142.0 358.0 259.2 33.6 42.6 38.6 196.0 625.0 367.8 52.8 58.7 55.2 121.0 356.0 223.8 30.4 34.8 32.5 139.0 398.0 264.3 35.4 39.7 37.2 to D2 third posterior fifth 4.4 14.9 7.3 0.9 1.4 1.1 fifth gill slits to tail tip 175.0 470.0 306.7 42.7 47.4 45.0 width each space to max. disc Internasal width 46.6 126.0 84.1 11.8 13.0 12.4 Character No. postorbital thorns No. interspiracular thorns lobe lobe between lobes Space btwn first gill slits Nasal curtain, length No. preorbital thorns width Center of anus to D1 V-length, anterior lobe Gill slit length, first Snout tip to center of anus Snout angle 85 91 88.0 Clasper, postanus length Journal of Marine Biology 5 m ± 1.91 1.11 2.53 0.63 0.40 0.40 0.20 ± ± ± ± ± ± ± m Min Max Mean Min Max Mean ± 1: Continued. Table Females (7) Males (6) 0.952.53 20 31 59 24.4 64 61.3 1.89 52 64 57.8 0.450.240.000.20 3 0 6 1 2 4.0 3 0 1.6 1.4 1 0.2 ± ± ± ± ± ± ± Absolute % TL Absolute % TL 354.0 121.6 111.0 010.2 23 2852 25.0 63 58.5 Min Max Mean Min Max Mean lower jaw 54 61 57.3 No. scapular thorns Character No. nuchal thorns No. interscapular thorns No. median thorns Tooth rows upper jaw No. middorsal thorns 6 Journal of Marine Biology m 0.66 3.15 0.89 0.34 1.13 0.48 1.19 0.05 0.21 0.27 0.15 0.24 0.44 0.59 0.12 0.04 0.13 0.26 0.27 0.15 0.49 0.29 0.07 0.13 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± erences are given in bold, number of specimens ff m Min Max Mean Min Max Mean na 129.0 544.0 360.0 25.2 41.5 35.1 na 54.3 285.0 143.1 13.2 19.2 16.8 0.39 23.1 142.0 87.4 7.4 9.5 8.8 na 17.0 32.1nana 3.4 24.6 3.2 17.1 2.2 25.3 10.3 2.7 13.0 2.4 0.9 0.9 1.2 1.7 1.1 1.2 na 12.2 34.5 18.8 1.0 3.9 2.2 0.06 55.4 215.0 132.8 14.0 19.2 16.1 1.90 92.5 429.0 276.7 28.2 30.7 29.5 1.95 174.0 851.0 531.7 54.2 57.1 56.1 0.50 197.0 1050.0 623.0 60.5 70.5 65.5 0.62 18.6 80.4 47.7 4.2 6.00.02 5.3 6.8 36.3 22.2 1.9 2.5 2.3 1.39 25.3 127.0 73.0 6.6 8.8 7.9 0.03 6.4 33.5 17.7 1.5 2.2 1.9 0.080.24 12.2 12.1 56.5 53.9 34.2 33.1 3.4 3.2 4.3 4.6 3.8 3.6 0.41 6.4 27.8 14.2 0.9 2.4 1.7 0.86 13.5 63.90.70 34.3 17.1 85.7 1.8 4.7 49.9 3.9 0.40 4.3 8.5 6.1 52.0 5.5 28.7 1.6 3.6 2.9 0.17 6.7 32.4 19.3 1.8 2.4 2.0 0.13 8.3 50.5 26.6 2.4 3.4 2.8 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± erent areas of the North Atlantic (significant di ff not available). = Females (3) Males (7) standard error, na = Absolute % TL Absolute % TL 9.9 23.5 16.7 0.7 1.5 1.1 22.4 na na 1.5 na 1.5 38.2 43.9 41.1 2.6 3.4 3.0 34.4 na na 2.2 na 2.2 16.1 na na 1.1 na 1.1 83.6 91.5 87.6 5.7 7.1 6.4 36.0 68.4 56.4 2.3 5.1 4.0 Min Max Mean Min Max Mean 32.9 36.8 34.9 2.5 2.6 2.5 81.4 94.0 87.1 5.2 7.3 6.1 42.6 53.2 47.9 2.9 3.4 3.2 23.9 26.6 25.3 1.6 1.7 1.7 45.9 51.6 48.8 3.1 3.3 3.2 455.0 na na 31.1 na 31.1 351.0 455.0 403.0 27.3 31.1 29.2 246.0 261.4 253.7 16.7 16.8 16.8 125.2 161.0 138.7 8.0 12.5 9.8 140.0 170.6 150.9 9.7 10.9 10.5 2: Morphometrics and meristics of male and female pale ray Bathyraja pallida from di prenasal na na na na na na 45.8 184.0 111.8 12.1 15.7 13.5 width at D1 lateral fold height at base length width at preoral 228.5 228.5 228.5 14.6 14.6 14.6 height at D1 length 672.0 859.0 791.0 52.3 58.8 55.0 base length TL, mmDisc, width 1285.0 845.0 1565.0 1015.7 1437.0 932.2 64.0 65.8 64.9 311.0 1490.0 948.3 Character origin length V-tips V-tips Mouth width Tail, postdorsal length origin Interspiracular width Interorbital width D1, height Orbit + spiracle length Head length, ventrally Snout length, preorbital D2, heightInterdorsal space 25.7 32.9 29.3 1.8 2.1 1.9 Orbit, horizontal diameter Spiracle length 38.5 39.9 39.2 2.7 3.0 2.9 C, base length 21.9 na na 1.5 na 1.5 examined are shown in parentheses, m Table Journal of Marine Biology 7 m 0.63 0.45 1.09 1.51 4.20 0.98 0.90 0.51 0.88 0.69 0.12 0.10 0.24 0.37 0.26 0.07 0.16 0.37 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.73 0.60 0.95 0.31 ± ± ± ± 26 24.0 22 m Min Max Mean Min Max Mean na 129.0 602.0 378.0 36.9 42.7 40.4 0.60 48.6 241.0 141.80.94 151.1 12.6 855.0 16.7 15.0 504.6 48.6 57.4 52.2 0.55 28.9 155.0 87.9 9.2 10.8 9.7 0.96 156.0 674.0 490.2 44.3 50.2 46.7 0.71 34.2 166.0 99.3 8.7 11.5 10.7 1.95 46.3 269.01.510.67 110.3 156.6 109.0 545.0 14.5 529.0 331.8 18.1 332.5 16.1 31.8 32.6 37.5 36.9 35.4 35.2 0.26 14.10.20 70.6 5.00.04 28.2 37.4 4.2 29.0 17.0 3.5 4.7 0.8 14.8 4.0 2.5 1.3 1.8 1.9 1.5 2.33 43.9 177.0 106.8 9.9 15.4 12.2 0.090.10 5.0 3.6 37.2 23.9 18.1 12.8 1.4 0.9 2.5 1.6 1.8 1.3 0.64 26.6 157.0 86.6 8.2 10.5 9.0 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 2: Continued. Table na 16 19 17.6 5.00 Females (3) Males (7) na 0 2 0.8 3.00 24 30 26.2 ± ± ± ± Absolute % TL Absolute % TL 1na1.0 16 na 16.0 25 31 28.0 25 35 30.0 na na na na na na 10.0 86.3 48.2 1.6 5.8 3.7 na na na na na na 24.5 402.0 212.3 7.9 27.6 17.3 87.0 167.0 127.0 6.8 11.4 9.1 Min Max Mean Min Max Mean 24.4 33.7 29.1 1.9 2.3 2.1 21.8 25.1 24.0 1.6 1.7 1.7 44.2 45.6 44.9 3.0 3.5 3.3 435.0 539.0 487.0 33.9 36.9 35.4 174.0 255.0 214.5 13.5 17.4 15.5 505.0 519.6 512.3 33.2 34.5 33.9 246.0 270.7 256.9 17.3 19.1 17.9 702.0 890.5 812.5 54.6 57.8 56.4 621.0 694.9 657.9 42.5 44.4 43.4 145.0 149.0 147.0 10.2 11.3 10.7 186.0 190.9 188.0 12.2 14.6 13.2 fifth gill slits to max. disc posterior space third 23.7 30.4 27.4 1.8 2.1 1.9 to tail tip width width each lower jaw to D2 599.0 na na 41.0 na 41.0 fifth 17.1 23.5 20.3 1.3 1.6 1.4 Internasal width 134.6 147.0 140.0 8.6 10.8 9.8 Character width lobe between lobes No middorsal thorns Clasper, postanus length lobe Center of anus to D1 Gill slit length, first V-length, anterior lobe No median thorns Space between first gill slits Tooth rows upper jaw Snout tip to center of anus Nasal curtain, length 8 Journal of Marine Biology m 1.97 1.59 1.45 0.78 0.27 0.78 0.72 0.40 0.17 0.27 0.32 ± 0.08 0.68 0.16 0.08 0.16 0.34 0.13 0.11 0.21 0.23 0.15 0.43 0.62 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± erences are given in bold, number ff erent areas of the North Atlantic (significant di ff m Min Max Mean Min Max Mean 1.58 98.8 384.0 196.8 33.9 54.3 40.1 0.65 76.1 637.9 314.5 41.8 59.9 53.1 0.29 14.4 130.3 58.8 7.9 11.5 9.9 0.56 93.9 784.0 382.5 51.6 70.3 65.7 0.53 14.6 145.0 74.50.25 23.5 7.5 122.4 15.3 12.2 63.9 10.2 14.1 11.3 0.53 44.4 264.0 133.6 20.0 28.7 25.1 0.38 14.9 147.3 76.1 8.2 16.3 12.7 0.18 10.2 45.1 21.6 3.5 5.6 4.3 0.30 8.7 28.70.21 17.4 11.5 52.4 1.9 5.6 28.5 3.7 4.8 7.5 5.7 0.08 0.0 7.9 3.6 0.0 1.0 0.6 0.650.10 0.0 7.8 44.20.06 38.80.10 3.3 21.9 4.0 13.4 15.7 15.1 0.0 2.4 6.3 8.1 7.1 4.3 4.4 0.9 3.1 1.0 2.0 2.7 1.3 1.5 0.45 9.6 117.8 41.7 5.3 10.4 6.9 0.100.10 4.2 4.4 16.6 20.4 9.1 9.8 1.3 1.4 2.8 2.5 1.8 1.8 0.56 12.0 102.0 52.00.12 5.90.12 9.5 11.9 9.1 38.3 9.2 36.0 19.8 19.6 2.8 2.8 5.4 5.0 3.7 3.8 0.15 4.0 20.0 11.90.27 11.8 1.8 32.8 3.4 2.4 19.7 2.9 7.0 4.4 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± Females (14) Males (13) standard error). = Absolute % TL Absolute % TL 3.8 18.8 10.0 1.0 1.7 1.2 8.6 47.73.3 25.1 20.3 2.5 11.1 3.6 2.9 1.1 2.3 1.3 0.0 52.4 29.1 0.0 7.9 4.0 0.0 14.5 5.2 0.0 1.0 0.6 7.6 64.0 32.3 2.6 4.8 3.7 28.8 180.4 104.7 9.0 12.8 11.3 21.6 211.0 118.3 9.0 15.4 12.9 53.3 413.0 221.3 22.2 28.3 26.0 16.8 161.5 70.5 5.2 11.1 7.5 Min Max Mean Min Max Mean 11.3 31.1 20.4 1.7 5.0 2.6 15.4 70.0 42.1 4.4 6.8 5.2 22.1 197.0 103.0 9.2 12.9 10.8 159.1 1042.0 626.6 64.4 72.3 68.1 111.1 481.0 274.0 30.9 46.3 36.5 121.0 922.0 525.6 50.4 60.3 56.2 3: Morphometrics and meristics of male and female Richardson’s ray Bathyraja richardsoni from di length base lengthbase length 10.1 10.3 50.9 45.0 30.8 28.4 2.8 2.9 4.6 4.3 3.4 3.5 preoral 24.5 206.6 120.5 10.2 14.5 13.2 height at D1 height at width at width at D1 lateral fold prenasal 15.4 139.0 76.3 6.4 11.5 9.4 TL, mmDisc, width 240.0 1530.0 924.0 182.0 1133.0 570.2 Character origin V-tips V-tips origin length Interspiracular width Tail, postdorsal length Snout length, preorbital Orbit, horizontal diameter Spiracle length 5.3 53.3 23.2 2.0 3.5 2.6 Head length, ventrally C, base length 11.4 44.2 27.1 2.8 5.5 3.8 Interorbital width D2, heightInterdorsal space 5.0 20.4 12.7 1.0 2.1 1.6 Orbit + spiracle length D1, height 5.8 20.5 13.8 1.1 2.4 1.6 Mouth width of specimens examined are shown in parentheses, m Table Journal of Marine Biology 9 m 2.20 2.05 0.1 0.77 0.56 1.22 1.54 2.15 0.40 0.37 0.08 0.10 ± 0.47 0.08 0.65 0.28 0.59 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.46 5.41 ± ± m Min Max Mean Min Max Mean 0.74 32.4 386.0 170.2 9.0 36.4 31.1 1.56 75.0 691.1 299.1 32.5 61.0 49.6 0.59 27.50.56 235.7 20.7 102.8 147.0 14.80.96 79.5 20.8 68.4 17.9 11.0 362.6 18.6 171.9 14.4 25.7 38.2 31.5 1.22 80.4 358.0 176.3 29.1 44.2 35.6 1.42 109.6 471.3 236.7 36.2 60.2 44.3 0.51 20.9 174.5 80.2 11.1 15.9 13.9 0.31 16.0 124.6 62.6 8.8 14.2 10.9 0.080.09 2.2 1.3 23.8 19.3 9.5 8.1 1.0 0.7 2.1 1.7 1.6 1.3 0.06 2.0 20.4 8.7 0.9 1.8 1.4 0.170.87 6.60.48 2.2 37.6 12.7 20.7 84.4 24.6 10.3 42.2 3.4 1.2 12.0 5.8 2.4 5.0 8.3 2.0 7.2 0.38 11.5 118.3 55.2 6.1 11.7 9.2 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 3: Continued. Table Females (14) Males (13) 0.74 13 18 15.2 3.69 70 133 96.4 ± ± Absolute % TL Absolute % TL 12 21 16.5 na na na na na na 12.2 127.7 48.6 6.4 12.0 8.6 5.0 77.7 22.0 1.6 12.4 2.9 2.6 26.2 14.9 1.1 1.9 1.5 2.2 25.5 14.0 0.8 1.9 1.5 3.1 30.2 17.3 1.3 2.2 1.8 13.8 117.7 61.0 2.2 8.5 7.0 90.5 566.0 298.1 25.1 37.7 31.5 33.4 238.0 132.5 12.9 18.7 15.6 19.2 149.0 77.9 6.2 10.1 8.7 11.8 70.6 37.3 3.0 5.5 4.6 46.6 308.5 171.7 13.6 21.4 18.5 Min Max Mean Min Max Mean 91.0 570.0 293.9 31.0 39.0 35.0 113.8 1010.0 539.9 46.1 66.0 56.0 to max. disc fifth third fifth gill slits 36.5 227.2 129.9 10.3to D2 16.6 14.2 103.0 471.0 276.4 29.3 42.9 35.3 width each space to tail tip 129.1 601.0 358.4 37.4 53.8 43.1 posterior Internasal width 26.4 174.6 99.6 8.0 12.8 11.0 Character width Snout angle 70 120 90.8 lobe between lobes Gill slit length, first Snout tip to center of anus Center of anus to D1 lobe Number of median thorns V-length, anterior lobe Clasper, postanus length Nasal curtain, length Space between first gill slits 10 Journal of Marine Biology m 0.53 0.45 1.72 0.44 0.72 0.70 0.20 0.21 0.09 0.09 0.18 0.10 0.19 0.19 0.14 0.15 0.15 0.19 0.15 0.21 0.35 0.10 0.22 ± 0.45 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± erences are given in bold, number of ff erent areas of the North Atlantic (significant di ff m Min Max Mean Min Max Mean 0.47 22.0 91.0 50.7 20.4 25.6 22.3 0.44 8.0 41.0 23.1 7.9 12.7 10.2 2.59 17.0 106.0 55.7 14.0 27.0 20.6 0.46 8.0 37.0 21.8 7.9 11.8 9.5 0.48 11.0 44.5 26.6 10.2 14.8 11.8 0.82 46.0 196.0 102.8 41.3 49.0 44.5 0.87 54.0 215.0 116.1 47.8 54.3 50.6 0.17 5.00.11 16.0 5.5 9.3 21.5 3.2 11.4 5.3 4.1 4.3 9.1 5.3 0.37 0.00.500.07 3.0 3.0 3.5 14.00.04 0.7 11.50.12 1.5 7.0 1.8 0.0 5.0 6.4 8.3 2.1 1.9 2.3 2.7 3.9 0.5 3.6 3.5 3.1 1.0 2.8 1.1 1.8 2.0 1.2 1.6 0.12 4.00.06 17.0 8.0 9.4 30.0 3.1 14.9 5.3 6.4 4.1 0.15 8.0 4.0 7.1 19.5 9.3 3.1 4.5 4.0 0.180.19 2.0 2.0 12.0 13.0 5.4 5.4 1.7 1.7 3.2 3.0 2.2 2.2 0.360.34 5.0 5.5 24.0 22.0 12.4 12.4 4.1 4.7 6.1 5.9 5.1 5.4 0.57 3.0 14.0 6.7 1.60.32 3.6 7.0 2.9 35.0 15.4 5.9 8.0 6.7 0.10 2.0 11.5 5.7 2.0 3.0 2.4 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± not available). = Females (4) Males (8) standard error, na = Absolute % TL Absolute % TL 1.8 8.0 4.4 1.1 1.8 1.5 3.24.5 12.5 18.7 8.2 11.4 2.6 3.2 3.1 4.6 2.9 4.0 1.4 4.8 3.0 1.0 1.4 1.1 0.04.0 5.0 12.0 1.1 8.6 0.0 1.9 2.8 5.9 0.6 3.4 4.2 19.07.2 11.8 29.9 3.8 19.5 4.7 6.6 4.2 7.1 6.9 5.0 16.55.0 10.5 21.5 3.4 13.1 4.9 4.1 3.8 5.2 4.7 21.3 122.0 66.1 12.1 29.0 20.5 10.5 55.3 31.5 9.4 13.4 11.0 Min Max Mean Min Max Mean 21.5 109.2 67.0 21.1 25.6 23.4 4: Morphometrics and meristics of male and female Bigelow’s ray Rajella bigelowi from di width at D1 lateral fold length 43.0 209.0 128.9 40.6 47.1 44.8 height at width at height at D1 prenasal 8.5 46.0 28.5 8.3 12.7 10.0 preoral 10.5 56.4 33.5 10.3 14.4 11.7 base lengthbase length 7.7 6.2 23.8 21.0 15.3 13.9 4.1 3.5 7.5 6.2 5.5 5.0 TL, mmDisc width 102.0 57.0 453.0 234.0 283.8 144.3 47.9 55.9 51.3 101.0 436.0 231.0 Character origin length V-tips V-tips origin C, base length 3.9 12.0 8.9 1.9 5.9 3.4 D1, height 1.4 12.0 6.5 1.4 2.6 2.1 Mouth width 8.3 28.3 17.0 4.9 8.1 6.3 Spiracle length 2.2 12.6 6.7 2.0 2.8 2.3 Snout length, preorbital D2, heightInterdorsal space 1.6Tail, postdorsal length 12.1 6.3 1.4 2.7 2.1 Orbit, horizontal diameter Interspiracular width Head length, ventrally Interorbital width Orbit + spiracle length specimens examined are shown in parentheses, m Table Journal of Marine Biology 11 m 0.19 0.25 0.42 0.49 2.30 0.61 0.43 0.50 0.11 0.07 0.14 0.08 0.43 0.44 0.09 0.23 0.23 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.88 0.39 0.26 ± ± ± m Min Max Mean Min Max Mean 0.21 14.00.420.55 58.0 13.0 13.0 56.0 30.5 61.0 29.7 12.3 32.6 14.2 11.5 13.3 11.9 13.8 16.0 12.8 13.8 0.852.23 39.00.99 23.3 180.0 47.0 130.0 190.0 91.3 56.5 36.0 106.5 10.2 41.3 43.0 30.1 39.4 48.9 24.5 46.1 1.00 53.0 215.0 119.5 49.3 54.5 51.9 0.82 59.0 249.0 137.4 57.1 61.7 59.5 0.160.06 2.0 1.0 13.00.11 6.5 1.5 6.0 5.0 3.2 2.0 2.8 0.8 3.3 2.0 2.5 0.9 1.4 1.6 1.3 0.14 1.0 6.0 3.0 0.9 1.6 1.2 0.49 4.8 16.0 9.6 3.0 5.9 4.6 0.07 1.0 4.8 2.3 0.7 1.6 0.9 0.21 9.0 35.0 18.4 6.8 9.1 8.2 0.17 8.0 29.0 14.5 5.5 7.9 6.9 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 4: Continued. Table Females (4) Males (8) 2.50 107.0 110.0 108.3 0.52 1 5 2.1 0.26 1 4 2.1 ± ± ± Absolute % TL Absolute % TL 242.4 263.1 na na na na na na 7.0 45.0 17.7 5.4 10.3 7.2 5.2 13.0 9.8 2.9 5.7 4.1 3.1 15.3 8.7 2.6 3.7 3.0 1.6 7.7 4.6 1.4 1.9 1.7 1.0 8.8 4.2 1.0 1.9 1.4 0.7 9.3 4.4 0.7 2.1 1.5 14.5 81.2 43.0 12.8 17.9 14.7 31.5 125.0 73.1 12.5 32.8 27.2 38.0 195.0 116.1 37.3 43.4 40.3 11.0 62.3 36.2 10.7 13.8 12.5 40.0 199.0 128.9 39.2 48.5 45.2 13.8 62.9 37.6 12.4 14.0 13.2 Min Max Mean Min Max Mean posterior fifth 1.0 7.1 3.3 1.0 1.6 1.1 to max. disc to D2 46.0 222.0 144.5 45.1 53.6 50.9 to tail tip 62.0 254.0 166.2 56.1 63.2 59.2 space third fifth gill slits 9.7 38.6 24.3 7.7 9.5 8.6 width each Internasal width 7.2 33.2 19.0 5.8 7.3 6.7 Character lobe width No. preorbital thorns Nasal curtain, length Snout tip to center of anus between lobes No. postorbital thorns Snout angle 106.0 111.0 108.5 lobe Clasper, postanus length Gill slit length, first V-length, anterior lobe Center of anus to D1 Space between first gill slits 12 Journal of Marine Biology m ± na 0.69 2.63 2.60 0.42 0.22 0.10 0.79 ± ± ± ± ± ± ± ± m Min Max Mean Min Max Mean ± 4: Continued. Table Females (4) Males (8) na 1 1 1.0 0.962.35 26 33 22 28.6 40 32.3 2.15 22 38 30.3 0.530.750.320.13 0 2 3 2 10 0.8 4 3.6 0 2.4 1 0.1 ± ± ± ± ± ± ± ± Absolute % TL Absolute % TL 041.3 284.6 11 1.0 242.6 010.1 22 38 30.7 25 33 29.4 Min Max Mean Min Max Mean lower jaw 24 36 29.2 No. interspiracular thorns Character No. scapular thorns No. interscapular thorns Tooth rows upper jaw No. nuchal thorns No. middorsal thorns No. median thorns Journal of Marine Biology 13 m 1.47 0.44 0.26 0.63 0.27 0.48 0.35 0.09 0.15 0.07 0.06 0.26 0.14 0.19 0.10 0.34 0.12 0.19 0.16 0.06 0.24 0.06 0.19 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± erences are given in bold, number ff erent areas of the North Atlantic (significant di ff m Min Max Mean Min Max Mean 0.30 78.6 170.0 133.1 13.2 22.5 18.4 0.32 337.0 442.0 412.2 56.0 58.5 57.5 0.25 83.8 111.0 99.4 13.2 15.0 13.9 0.84 156.6 203.5 182.9 22.8 26.9 25.6 0.39 94.2 111.5 103.9 13.2 16.0 14.6 0.53 80.1 96.9 89.1 11.8 13.4 12.5 0.50 299.0 394.0 366.5 50.1 52.3 51.1 0.09 23.9 32.1 27.7 3.7 4.2 3.9 0.25 27.3 42.3 36.1 4.6 5.6 5.0 0.16 8.2 12.00.04 6.2 10.2 11.0 1.2 8.0 1.6 1.4 1.0 1.5 1.1 0.47 24.0 37.20.130.18 42.4 29.0 33.3 56.8 42.9 3.2 51.0 4.9 36.30.02 6.7 4.1 0.06 4.5 15.9 7.5 20.7 5.7 23.00.01 7.1 38.9 5.1 9.2 20.2 29.1 16.4 2.4 3.0 13.3 3.0 5.1 2.8 1.5 4.0 2.2 1.8 0.300.10 14.0 17.9 27.6 28.6 22.2 22.0 2.3 2.7 3.7 3.8 3.1 3.1 0.22 31.00.16 38.0 8.2 34.6 12.0 4.1 10.2 5.9 1.2 4.9 1.6 1.4 0.05 45.5 57.8 54.4 7.3 7.8 7.6 0.17 14.0 21.7 19.1 1.8 3.1 2.7 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± not available). = Females (2) Males (6) standard error, na = Absolute % TL Absolute % TL 6.7 7.2 7.0 1.1 1.2 1.2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 8.9 10.8 9.9 1.5 1.8 1.6 11.3 11.4 11.4 1.9 1.9 1.9 17.2 17.4 17.3 2.8 2.9 2.9 25.2 26.0 25.6 4.2 4.3 4.2 28.6 30.9 29.8 4.8 5.1 4.9 40.8 42.5 41.7 6.8 7.0 6.9 21.8 27.5 24.7 3.6 4.6 4.1 83.3 86.6 85.0 13.8 14.3 14.1 Min Max Mean Min Max Mean 24.2 25.4 24.8 4.0 4.2 4.1 33.3 36.2 34.8 5.5 6.0 5.8 151.4 162.0 156.7 25.1 26.8 26.0 335.0 340.0 337.5 55.6 56.3 56.0 124.0 128.0 126.0 20.6 21.2 20.9 5: Morphometrics and meristics of male and female Mid-Atlantic skate Rajella kukujevi from di length 301.0 308.0 304.5 50.0 51.0 50.5 width at D1 preoral 85.7 90.7 88.2 14.2 15.0 14.6 base lengthbase length 29.0 31.6 30.3 4.8 5.2 5.0 height at width at height at D1 lateral fold prenasal 74.5 81.2 77.9 12.4 13.4 12.9 TL, mmDisc, width 602.0 604.0 603.0 597.0 757.0 716.2 Character origin V-tips V-tips origin length Interorbital width Orbit + spiracle length D1, height 14.7 18.3 16.5 2.4 3.0 2.7 Interspiracular width Mouth width 45.0 45.8 45.4 7.5 7.6 7.5 Orbit, horizontal diameter Head length, ventrally Snout length, preorbital C, base length 8.9 10.8 9.9 1.5 1.8 1.6 Interdorsal space Tail, postdorsal length Spiracle length 15.7 17.8 16.8 2.6 2.9 2.8 D2, height 17.1 18.2 17.7 2.8 3.0 2.9 of specimens examined are shown in parentheses, m Table 14 Journal of Marine Biology m 0.35 3.29 0.71 0.38 0.88 2.43 0.56 0.53 0.43 0.09 0.06 0.13 0.11 0.06 0.10 0.40 0.33 0.44 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 2.44 0.17 0.54 0.79 0.54 1.21 ± ± ± ± ± ± m Min Max Mean Min Max Mean 0.22 80.5 103.5 92.90.24 11.4 78.2 13.7 244.0 13.0 150.7 11.3 32.2 20.9 0.34 85.0 109.1 98.4 11.2 14.9 13.8 0.21 101.20.59 149.0 276.00.98 129.6 367.0 243.0 15.2 335.7 317.0 19.8 44.9 289.5 18.1 48.7 39.0 46.9 41.9 40.4 0.90 273.0 351.0 322.5 43.4 46.4 45.0 0.92 315.0 403.0 364.5 47.2 53.2 51.0 0.50 58.0 79.0 67.6 7.7 10.5 9.5 0.11 8.9 12.8 10.8 1.3 1.7 1.5 0.12 22.90.14 35.9 8.6 16.00.21 31.1 7.0 13.9 3.8 10.5 4.8 1.4 4.3 2.1 8.5 1.9 1.0 1.4 1.2 0.28 9.0 13.1 11.7 1.2 1.8 1.6 0.17 42.5 67.5 57.4 7.1 9.0 8.2 0.18 62.9 68.7 64.9 8.3 10.6 9.1 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 5: Continued. Table Females (2) Males (6) 2.00 79.0 96.0 87.0 0.25 0 2 1.2 1.000.750.252.00 3 0 6 2 5 4.1 10 2 3.0 6.6 5 3.8 ± ± ± ± ± ± Absolute % TL Absolute % TL 242.8 586.3 486.0 263.5 121.8 na na na na na na 33.0 33.7 33.4 4.4 4.5 4.5 na na na na na na 49.9 168.0 118.4 8.4 22.2 16.2 8.5 9.8 9.2 1.4 1.6 1.5 11.2 12.9 12.1 1.9 2.1 2.0 79.4 83.2 81.3 13.1 13.8 13.5 25.6 26.9 26.3 4.2 4.5 4.4 Min Max Mean Min Max Mean 82.0 84.9 83.5 13.6 14.1 13.8 87.4 90.0 88.7 14.5 15.0 14.7 103.0 105.2 104.1 17.1 17.5 17.3 237.0 248.0 242.5 39.2 41.2 40.2 275.0 283.0 279.0 45.7 46.9 46.3 to tail tip 311.0 321.0 316.0 51.5 53.3 52.4 width each third 8.8 12.2 10.5 1.5 2.0 1.7 posterior to D2 269.0 279.0 274.0 44.5 46.3 45.4 widthspace 48.4 50.6 49.5 8.0 8.4 8.2 to max. disc fifth gill slits 51.4 53.8 52.6 8.5 8.9 8.7 fifth 7.0 9.6 8.3 1.2 1.6 1.4 Internasal width 58.0 64.2 61.1 9.6 10.6 10.1 Character lobe No. of postorbital thorns No. of orbital thorns lobe No. of interspiracular thorns V-length, anterior lobe between lobes Space between first gill slits width Gill slit length, first Snout angle 87.0 91.0 89.0 Center of anus to D1 No. of nuchal thorns Nasal curtain, length Snout tip to center of anus No. of preorbital thorns Clasper, postanus length Journal of Marine Biology 15 m ± 3.44 3.55 5.09 0.58 1.17 1.91 3.79 0.62 0.63 ± ± ± ± ± ± ± ± ± m Min Max Mean Min Max Mean ± 5: Continued. Table Females (2) Males (6) na 35 43 38.7 4.00 99 118 106.4 4.000.508.500.00 0 55 25 57 79 25 14.0 89 66.3 28 68.8 26.2 1.00 31 44 39.7 1.001.00 0 0 5 4 2.4 2.0 ± ± ± ± ± ± ± ± ± Absolute % TL Absolute % TL 243.0 021.0 40 na 40.0 38 40 39.0 21 29 25.0 3925 56 25 47.5 25.0 57 58 57.5 105 113 109.0 Min Max Mean Min Max Mean No. of scapular thorns Character No. of interscapular thorns Total no.median of thorns Tooth rows upper jaw Lateral spines left No. trunk vertebrae No. caudal vertebrae Tooth rows lower jaw Lateral spines right 16 Journal of Marine Biology width, and the number of median thorns. maximum eye diameter [6]. Also, many North Pacific skate The morphology of Rajella bigelowi has been docu- species from Japanese waters have shown sexual dimorphism mented better than all the other species in our study, with in snout lengths, lengths of the pelvic fins, and tail lengths published data on 30 specimens [31, 33]. In a recent study, [3]. additional data on the morphology and meristics of R. Our study shows that North Atlantic deepwater skates bigelowi from the North Atlantic was provided [35], based from the genera Amblyraja, Bathyraja, and Rajella exhibit on specimens from the MCZ and MHNH and two neonates sexual dimorphism most frequently in the following charac- collected from the Mid-Atlantic Ridge (ZMUB). However, ters: interorbital width and length of the third gill slit (three there have been no investigations concerning the sexual of five species), disc length and width, horizontal diameter of dimorphism of this species. Our analysis of 18 specimens of the orbit, length of the fifth gill slit, space between first gill R. bigelowi showed that males and females of this species slits, space between fifth gill slits, length of the second dorsal differ significantly in the following characters (Table 4): fin base, mouth width, length and width of each lobe of the interorbital width, length of the orbit + spiracle (measured nasal curtain, distance from the snout tip to the center of the together), head length, length of the nasal curtain, width anus, distance from the snout to the point of maximum disc of each nasal curtain lobe, length of the third and fifth width, length of lateral fold, length of the orbit + spiracle gill slits, and the number of preorbital thorns. Some of the (measured together), tail height at the pelvic fin tips, and the thorn counts for this species varied on the left and right number of median thorns (two of five species). sides of the specimen (i.e., orbital thorns, scapular thorns, Sexual dimorphism in disc length and the distance from etc.). Therefore, the maximum, minimum, and mean values the snout tip to the anus has been noted for other skate for these characters are shown for one side of the . species [6, 14, 15, 26]. This is probably due to the larger Apparent sexual dimorphism of meristic characters could be size attained by females, compared to males of the same age due to our small sample size or low variation among the [8–11, 16]. The same reason may cause differences between specimens observed. males and females in the length of the lateral fold, distance Morphometric and meristic data from Rajella kukujevi from the snout tip to the point of maximum disc width, and are published in a single paper, which is the original de- the number of median thorns. scription of the species [32]. Unfortunately the description Our study shows that females of some species have of this species included only a small number of characters. a relatively wider disc compared to males and this is Since then, only three specimens have been collected [50, 53], likely responsible for the observed differences in interorbital but these subsequent records lack any reporting of mor- width, length of gill slits, length of the orbit + spiracle phometric or meristic data. Therefore, the morphology of (measured together), and the space between the gill slits. thisspecieshasbeenscantlyreportedandnodataonsexual Differences in mouth width in some species may be caused dimorphism are available. by sexual dimorphism of the shape and number of teeth in The males and females we examined differ in the fol- adult skates, as well as differences in diet [3, 9–11, 15, 17–23]. lowing characters (Table 5): disc width, interorbital width, The same cause might be responsible for differences between length of the second dorsal fin base, lateral fold length, males and females in size of the nasal curtain. space between the first gill slits, distance between the We also observed differences between males and females snout and the point of maximum disc width, number of in the tail height at the tips of pelvic fins. Since the tail is used interspiracular and median thorns, number of lateral spines in courtship and copulation, it is reasonable to assume that on the right and left sides of the tail, and the number of trunk these differences can be attributed to reproductive behaviour. vertebrae. Like R. bigelowi, the apparent sexual dimorphism Forster [37] noted the existence of minor sexual differ- of meristic characters could be due to our small sample size ences in colour patterns of Bathyraja richardsoni that may (only two females examined) or low variation among the be related to limited observations (single male and single specimens observed. Conversely, other characters might be female examined) and is likely attributable to individual sexually dimorphic but not detected by our analysis, owing variation. Our study did not reveal significant differences to very high variation in some characters (i.e., median thorns in colouration between males and females in any of the and lateral spines). Also, like R. bigelowi, the maximum, five species examined. However, ontogenetic changes in minimum, and mean values for some of the thorn counts colour pattern were observed in four of the five species were given for one side of the animal. (A. jenseni, B. pallida, B. richardsoni, R. bigelowi), while R. Studies of sexual dimorphism in batoids are limited. kukujevi demonstrated considerable individual variation in However, these previous studies found sexual dimorphism colouration. in various morphological characters. For example, males and females of the South American apron ray, Discopyge tschudii, and Patagonian skate, Bathyraja macloviana,differ Acknowledgments in disc length [15, 26]. Male and female zipper sand skates, Psammobatis extenta, from Argentinean waters exhibit sexual This paper would not have been possible without the input dimorphism in the prenasal snout length, distance between of our many colleagues. Matthias Stehmann (ICHTHYS, the anus and tail tip, and distance between the snout tip and Hamburg, Germany) helped with the ID of skates. James Orr anus [14]. The thorny skate, Raja clavata, from the Adriatic (Alaska Fisheries Science Center, Seattle, USA) and Hajime Sea exhibits sexual dimorphism in the disc length and Ishihara, (W & I Associates Corporation, Fujisawa, Japan) Journal of Marine Biology 17 explained some specific measurements. Romain Causse [12] Z. S. Almedia, J. S. Nunes, C. L. Costa et al., “Report of (Museum National d’Histoire Naturelle, Paris, France) made Urotrigon microphthalmum (Elasmobranchii: Urolophidae) X-ray images of Rajella kukuevi and R. bigelowi from from Maranhao (Brazil)’s shallow waters and notes about its museum specimens. Ingvar Byrkjedal, (Zoological Museum, biology,” Boletin de Investigaciones Marinas y Costeras, vol. 29, University of Bergen, Bergen, Norway), Bernard Seret,´ pp. 67–72, 2000 (Portuguese). (Museum National d’Histoire Naturelle, Paris, France), [13] T. Gedamke, W. D. DuPaul, and J. A. Musick, “Observations Karsten Hartel and Andy Williston, (Museum of Compara- on the life history of the barndoor skate, Dipturus laevis, on tive Zoology, Harvard, USA), Patrick Campbell and Roberto Georges Bank (Western North Atlantic),” Journal of Northwest Atlantic Fishery Science, vol. 35, pp. 67–78, 2005. Miguez, (British Museum of Natural History, London, Great [14] J. M. Braccini and G. E. Chiaramonte, “Intraspecific variation Britain), Geoff Swinney, (National Museums of Scotland, in the external morphology of the sand skate,” Journal of Fish Edinburgh, Scotland), and Monty Priede, (Oceanlab, Uni- Biology, vol. 62, no. 4, pp. 959–972, 2002. versity of Aberdeen, Newburgh, Scotland) made possible the [15] L. B. Scenna, Distribution, abundance and some biological as- examination of museum material and provided the facilities pects of the Patagonian skate Bathyraja macloviana (Rajidae) and equipment for these analyses. Boris Shieko (Zoological from the continental shelf off Argentina and Uruguay,M.S. Institute Russian Academy of Science, St. Petersburg, Russia) thesis, Universidad Nacional de Mar del Plata, Mar Del Plata, made measurements of the R. kukujevi holotype. Natalia Argentina, 2003. Popova (VNIRO) made the merisitic calculations from X-ray [16] N. L. Ruocco, L. O. Lucifora, J. M. Diaz de Astarloa, and O. images. The authors are grateful to these colleagues for their Wohler,¨ “Reproductive biology and abundance of the white- valuable contributions to this paper. dotted skate, Bathyraja albomaculata, in the Southwest At- lantic,” ICES Journal of Marine Science, vol. 63, no. 1, pp. 105– 116, 2006. References [17] A. Feduccia and H. Slaughter, “Sexual dimorphism in skates ff [1] D. A. 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