Chimaera notafricana Kemper, Ebert, Compagno & Didier, 2010, sp. nov

Autor: Kemper, Jenny M., Ebert, David A., Compagno, Leonard J. V., Didier, Dominique A.
Rok vydání: 2010
Předmět:
DOI: 10.5281/zenodo.5697975
Popis: Chimaera notafricana sp. nov. Cape chimaera Figures 1, 2; Tables 1, 2 Chimaera monstrosa: Dum��ril 1865: 688; Gilchrist 1902: 162; Thompson 1914: 166; Gilchrist 1922: 5; Barnard 1925: 94; Fowler 1936: 143; Fowler 1941: 489; Barnard 1947: 30, probably not Pl. 5, Fig. 3 = C. monstrosa from European seas; Smith 1949: 76; Smith 1965: 76; Stehmann and B��rkel 1984: 213; Compagno 1986: 144, not Fig. 32.1, which is European C. monstrosa; van der Elst and Vermeulen 1986: 4. Chimaera vaillanti: Dean 1906: 7 (MNHN 2557), nomen nudnum. Chimaera sp.: Compagno et al. 1989: 120, ill.; Compagno et al. 1991: 70; Compagno 1999: 120. Holotype: SAM 34517, adult male, 837 mm TL, 509 mm BDL; Cape Agulhas, southern Africa (34 �� 49 ��� 9 ���S, 20 ��00���0���E), by the M/V Boulonnais, station 36.09.72, 18 September 1996. Paratypes: 4 specimens: SAM 34428, adult male, 820 mm TL, 486 mm BDL, southern Africa (34 �� 43 ��� 3 ���S, 18 ��03��� 6 ���E), R/V Africana, station A 7026, cruise 0 60, number 12 -03B, 12 March 1988, 717 m; SAIAB 27132, adult female, 930 mm TL, 517 mm BDL, southern Africa (32 �� 30 ��� 5 ���S, 16 �� 24 ��� 3 ���E), R/V Africana, station A 5249, cruise 0 50, number E 05, 12 Jan. 1987, 800 m; SAIAB 27133, adult female, 925 mm TL, 522 mm BDL, southern Africa (32 �� 30 ��� 5 ���S, 16 �� 24 ��� 3 ���E), R/V Africana, station A 5249, cruise 0 50, number E 05, 12 Jan. 1987, 800 m; SAM 34429, adult female, 880 mm TL, 534 mm BDL, southern Africa (34 �� 55 ��� 6 ���S, 18 �� 11 ��� 7 ���E), R/V Africana, station A 7037, cruise 0 60, number 15 -04B, 14 March 1988, 903 m. Diagnosis. A species assigned to the genus Chimaera based on the presence of an anal fin separate from the ventral caudal margin by a notch. Chimaera notafricana is distinguished from its congeners by a combination of the following characters: uniform blackish brown color with dark bluish streaking, precaudal tail with longitudinal light and dark stripes; dorsal spine when depressed reaches past origin of second dorsal fin; large triangular pectoral fins, when depressed reaches just to pelvic-fin origin; caudal fin ventral margin terminating very slightly posterior to caudal fin dorsal margin insertion; males with short pelvic claspers that are externally trifid, 12.1���12.3 % BDL, not extending past distal tip of pelvic fins, divided for distal one-third of length; distance from anterior base of dorsal fin spine to center of supratemporal canal short (6.5���14.8 % HDL). Description. Morphometric measurements of holotype and four paratypes are presented in Table 1. The following proportions include the holotype followed by the paratypes range in parenthesis. A medium bodied species with a relatively large head 21.5 % BDL (20.7 ���23.0% BDL), about 18.0% of precaudal length. Trunk compressed, stout, height greater than width; body depth about uniform to pelvic-fin origin where it quickly tapers posteriorly, transitioning to caudal filament. Snout tip short, blunt, overhanging nostrils and mouth. Distance from snout tip to pre-orbital nearly one-half head length. Eyes large, oval, about 30.2 % HDL (26.5��� 33.3 % HDL), eye height at least 55.0% of eye length, with horizontal axis sloping posteroventrally. Pectoralpelvic space 32.4 % BDL (29.4���35.2 % BDL), about 1.5 times head length, and about 63.0% less than pelvicanal space 51.7 % BDL (56.2���60.7 % BDL). Pelvic-caudal space 56.4 % BDL, pelvic-fin insertion to ventral caudal-fin origin, is about equal to snout-vent length 57.0% BDL (58.2���60.3 % BDL). Skin is smooth, without denticles (except on secondary sexual organs), thin, and deciduous. Pectoral fins large and triangular, anterior margin long 38.9 % BDL (34.3���38.9 % BDL), about 1.8 times head length; anterior margin relatively straight to moderately convex with curvature beginning about one-half distal length to a slightly rounded fin tip; posterior margin straight, slightly concave one-fourth distal to tip, inner margin broadly rounded; fin tip when depressed reaches to origin of second dorsal fin and just to origin of pelvic fin. Pelvic fins about one-half as large, 18.1 % BDL (17.6���20.9 % BDL), as pectoral fins; anterior margin weakly convex, apex slightly rounded; posterior margin moderately convex, inner margin rounded. First dorsal-fin base short 13.4 % BDL (12.5���13.8 % BDL), preceded by a strong dorsal spine 22.1 % BDL (15.9���18.5 % BDL). Spine moderately curved, more so near distal tip, slightly longer than head length; upper one-half of spine free from first dorsal fin; anterior edge of spine with a prominent keel, deep grooves present on either side of keel; serrations may be present on posterior margin, but were not present on holotype (possibly worn in adults). First dorsal-fin apex below dorsal spine tip, length at least three-fourths head length. First dorsal-fin origin is approximately one-third distance of pectoral fin origin; anterior margin convex, posterior margin nearly straight. First dorsal-fin and spine when depressed reaches past second dorsal-fin origin. Second dorsal-fin origin is about one-half the distance between pectoral-fin insertion and pelvic-fin origin. Second dorsal-fin base long, 74.3 % BDL (73.8���77.9 % BDL), low, height relatively uniform throughout, but with greatest height at posterior one-third of fin length, margin not undulating, mostly straight. Second dorsal-fin height is less than one-third that of first dorsal-fin height; posterior end of second dorsal curves abruptly downwards to caudal origin. Caudal fin moderately elongate, lanceolate, broad, becoming filamentous; dorsal-lobe insertion is slightly anterior to ventral-lobe insertion; ventral-lobe length about equal to head length; dorsal and ventral rayed portions are nearly equal in height; height nearly equal to or slightly less than second dorsal fin height. Anal fin small, low, and with a pointed tip that extends at least as far as insertion of second dorsal fin, with a small notch separating it from ventral caudal fin margin; originates below second dorsal fin. Frontal tenaculum present on adult males; short, slender stalk enlarges to a bulbous tip, length about onehalf eye length, containing slender spines arranged in indistinct rows located on ventral and upturned dorsal side of tip. Paired pelvic claspers externally trifid, total length 12.3 % BDL (12.1 % BDL), forked for distal one-third of their length, not extending beyond distal tip of pelvic fins; medial branch slender, rod-like, smooth, and with small dilated tip; two lateral branches broader, each with a fleshy bulbous tip and denticles. Prepelvic tenacula present with 4 spines along medial edge. Lateral line canals measurements of holotype and paratypes are presented in Table 2. Lateral line canals of the head are open grooves, those on snout with wide dilations. Oral and preopercular canals share a common branch off the infraorbital canal in holotype, not recorded in paratypes. Lateral line canal measurements have been shown to be variable within species with respect to the branching patterns below the eye (e.g. H. melanophasma). Thus, more specimens are needed to determine if the branching pattern can be used as a diagnostic character. Distance from anterior base of dorsal fin spine to center of supratemporal canal short (6.5���14.8 % HDL). Lateral line canal of trunk originates anteriorly at fork between occipital and otic canals. A shallow sigmoid curve is present at fork, before origin of dorsal spine, then runs mostly straight extending posteriorly beneath bases of dorsal fins, at caudal region, extends ventrally and continues to caudal filament. Color. Preserved specimens a uniform dark brown with light color variations where outer skin is missing. Pectoral fin color is moderately dark brown, becoming a lighter brown along posterior edges, with a bluish hue near fin edges. Dorsal and pelvic fins are a dark brown, with a bluish hue. Dorsal fin spine light brown, becoming darker in grooves. Caudal fin lobes are moderately brown, darker near fin base, but lighter near fin apices. In life this species is a uniform blackish brown, with dark bluish streaking, precaudal tail with longitudinal light and dark stripes, no light spots or silvery sheen. Claspers are purplish in color, except at fleshy tips which are pale. Etymology. The Latin name is derived from the Greek notos meaning south and Latin Africanus, of Africa, referring to its known distribution. Vernacular: Cape chimaera Distribution and ecology. Southeastern Atlantic Ocean from off L��deritz, Namibia, around the Cape of Good Hope and eastwards to Algoa Bay, Eastern Cape Province, South Africa. This species has a reported depth range of 680 to 1000 m (Compagno et al. 1989; 1991). Comparisons. Chimaera notafricana is the only member of the genus Chimaera presently known to occur off southern Africa. The closest congener to C. notafricana is C. monstrosa, but it is easily distinguished by a combination of morphological characters and coloration. Chimaera notafricana and C. monstrosa, like other chimaera species, exhibit sexual dimorphism between males and females, therefore, comparisons of proportional body measurements between the two species were made between males and females separately. Also, ontogenetic differences are present in at least C. monstrosa, and only specimens with a BDL of 400 mm or more, indicating mature specimens, were used for comparative purposes. Chimaera notafricana males are distinct from C. monstrosa males in morphological characters including: shorter snout-vent length (57.0��� 59.7 vs. 60.0���62.0% BDL), shorter pre-second dorsal length (43.8 ���45.0 vs. 46.0���55.0% BDL), shorter pre-first dorsal length (23.2���23.3 vs. 24.0���32.0% BDL), shorter first dorsal-fin base (13.4���13.5 vs. 17.0���21.0% BDL), shorter dorsal-spine anterior margin (16.2���22.1 vs. 21.0���26.0% BDL), shorter first dorsal-fin height (16.5���18.8 vs. 20.0���22.0% BDL), shorter caudal-fin dorsal margin (18.8���20.9 vs. 23.0���28.0% BDL), shorter head length (21.5���21.9 vs. 22.0���26.0% BDL), shorter eye length (6.3���6.5 vs. 7.0���9.0% BDL), and shorter eye height (3.7���4.5 vs. 5.0���6.0% BDL). Chimaera notafricana has a much shorter ventral caudal margin than C. monstrosa (21.6���28.6 vs. 40.0���85.0% BDL); ventral margin in C. monstrosa extends greatly posterior to dorsal margin being variable within species (40.0���85.0 vs. 23.0���28.0% BDL); ventral margin insertion in C. notafricana is just posterior to dorsal margin insertion (21.6���28.6 vs. 18.8���20.9 % BDL). Chimaera notafricana also differs from C. monstrosa in the structure of the pelvic claspers: C. notafricana claspers are short, total length 12.1���12.3 % BDL, divided for distal one-third of length, and do not extend past distal tip of pelvic fins compared to C. monstrosa claspers which are long, total length 20.0���23.0% BDL, divided for over one-half distal length, and extend past distal tip of pelvic fins. Prepelvic tenaculum of C. notafricana with 4 spines on medial edge, C. monstrosa contains 6���7 spines. Chimaera notafricana females are distinguished from C. monstrosa females by a shorter pre-second dorsal length (42.5���46.4 vs. 48.1 ���57.0% BDL), shorter pre-first dorsal length (24.5���26.1 vs. 29.0���33.0% BDL), longer second dorsal-fin anterior height (5.4���6.7 vs. 4.0��� 5.5 % BDL) and posterior height (5.2���5.8 vs. 3.0���5.0% BDL), shorter first dorsal-fin base (12.5���13.8 vs. 13.5 ���20.0% BDL), shorter dorsal spine anterior margin (15.9���18.5 vs. 18.0���26.0% BDL), shorter first dorsal-fin height (13.8���14.8 vs. 17.2 ���22.0% BDL), shorter eye height (3.9���4.9 vs. 5.0��� 6.7 % BDL), shorter distance from anterior edge of first dorsal fin base to anterior edge of pectoral fin base (12.8���15.7 vs. 19.0���22.0% BDL), and a shorter distance from anterior edge of second dorsal fin base to anterior edge of pectoral fin base (23.6���27.1 vs. 29.0���34.0% BDL). Chimaera notafricana is also distinguished from C. monstrosa by an anal fin tip that reaches past insertion of second dorsal fin versus an anal fin tip that does not reach to insertion of second dorsal fin in C. monstrosa. Chimaera notafricana can also be distinguished from C. monstrosa by the shape of the pelvic fin, i.e. square to triangular in shape and slightly rounded near base versus very rounded. The pectoral fin of C. notafricana when depressed posteriorly reaches just to origin of pelvic fin base compared with C. monstrosa pectoral fin when depressed reaches past insertion of pelvic fin base. Lateral line canals of the head, particularly IOA, LRC, and SPS of C. notafricana are different from C. monstrosa (Table 2). The IOA in males is slightly longer in C. notafricana (15.1���16.8 vs. 11.6 ���15.0% HDL); LRC in females is longer in C. notafricana (8.9���9.7 vs. 4.3���6.4 % HDL) and the SPS, the distance from anterior base of dorsal spine to center of supratemporal canal, is longer in male and female C. monstrosa, 6.5��� 14.8 % HDL in C. notafricana vs. 16.1���28.3 % HDL in C. monstrosa. Chimaera notafricana is characterized by a uniform blackish brown color with dark bluish streaking, precaudal tail with longitudinal light and dark stripes. Chimaera monstrosa is characterized by a silvery color on back and flanks, mottled with brown spots and undulating stripes, pale ventrally; fins grayish, distal edges of unpaired fins are black (Stehmann & B��rkel 1984). Comparative material. Chimaera monstrosa. 23 specimens: USNM 17492, adult male, 800 mm TL, 400 mm BDL, Atlantic Ocean (Norway); MNHN 21���137, adult male, 919 mm TL, 419 mm BDL, Atlantic Ocean (Cotes d���Espagne); MNHN 3, adult male, 906 mm TL, 403 mm BDL, Atlantic Ocean (Scotland), 58 �� 40 ���N, 9 �� 30 ���W, 600 m; MNHN 13, adult male, 655 mm TL, 403 mm BDL, Atlantic Ocean (Scotland), 58 �� 40 ���N, 9 �� 30 ���W, 600 m; MNHN 14, adult male, 845 mm TL, 432 mm BDL, Atlantic Ocean (Scotland), 58 �� 40 ���N, 9 �� 30 ���W, 600 m; MNHN 16, adult male, 712 mm TL, 409 mm BDL, Atlantic Ocean (Scotland), 58 �� 40 ���N, 9 �� 30 ���W, 600 m; MNHN 17, adult male, 795 mm TL, 414 mm BDL, Atlantic Ocean (Scotland), 58 �� 40 ���N, 9 �� 30 ���W, 600 m; MNHN 18, adult male, 850 mm TL, 418 mm BDL, Atlantic Ocean (Scotland), 58 �� 40 ���N, 9 �� 30 ���W, 600 m; MNHN 19, adult male, 826 mm TL, 430 mm BDL, Atlantic Ocean (Scotland), 58 �� 40 ���N, 9 �� 30 ���W, 600 m; MNHN 20, adult male, 688 mm TL, 403 mm BDL, Atlantic Ocean (Scotland), 58 �� 40 ���N, 9 �� 30 ���W, 600 m; MNHN 24, adult male, 864 mm TL, 420 mm BDL, Atlantic Ocean (Scotland), 58 �� 40 ���N, 9 �� 30 ���W, 600 m; MCZ 326, adult female, 725 mm TL, 462 mm BDL, no data; MCZ 855, adult female, 774 mm TL, 449 mm BDL, Atlantic Ocean; USNM 10234, adult female, 708 mm TL, 453 mm BDL, Atlantic Ocean (Norway); MNHN 1, adult female, 834 mm TL, 485 mm BDL, Atlantic Ocean (Scotland), 58 �� 40 ���N, 9 �� 30 ���W, 600 m; MNHN 8, adult female, 817 mm TL, 423 mm BDL, Atlantic Ocean (Scotland), 58 �� 40 ���N, 9 �� 30 ���W, 600 m; MNHN 9, adult female, 916 mm TL, 488 mm BDL, Atlantic Ocean (Scotland), 58 �� 40 ���N, 9 �� 30 ���W, 600 m; MNHN 10, adult female, 902 mm TL, 421 mm BDL, Atlantic Ocean (Scotland), 58 �� 40 ���N, 9 �� 30 ���W, 600 m; MNHN 11, adult female, 980 mm TL, 469 mm BDL, Atlantic Ocean (Scotland), 58 �� 40 ���N, 9 �� 30 ���W, 600 m; MNHN 12, adult female, 895 mm TL, 430 mm BDL, Atlantic Ocean (Scotland), 58 �� 40 ���N, 9 �� 30 ���W, 600 m; MNHN 21, adult female, 830 mm TL, 408 mm BDL, Atlantic Ocean (Scotland), 58 �� 40 ���N, 9 �� 30 ���W, 600 m; MNHN 23, adult female, 830 mm TL, 427 mm BDL, Atlantic Ocean (Scotland), 58 �� 40 ���N, 9 �� 30 ���W, 600 m; LJVC-0459, adult female, 850 mm TL, 541 mm BDL.
Published as part of Kemper, Jenny M., Ebert, David A., Compagno, Leonard J. V. & Didier, Dominique A., 2010, Chimaera notafricana sp. nov. (Chondrichthyes: Chimaeriformes: Chimaeridae), a new species of chimaera from southern Africa, pp. 55-63 in Zootaxa 2532 on pages 56-61, DOI: 10.5281/zenodo.293361
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