Pleuronectiformes: Cynoglossidae: Symphurus) Collected at Volcano–19, Tonga Arc, West Pacific Ocean
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Zootaxa 3061: 53–66 (2011) ISSN 1175-5326 (print edition) www.mapress.com/zootaxa/ Article ZOOTAXA Copyright © 2011 · Magnolia Press ISSN 1175-5334 (online edition) Description and biological observations on a new species of deepwater symphurine tonguefish (Pleuronectiformes: Cynoglossidae: Symphurus) collected at Volcano–19, Tonga Arc, West Pacific Ocean THOMAS A. MUNROE1,3, JENNIFER TYLER2 & VERENA TUNNICLIFFE2 1National Systematics Laboratory, National Marine Fisheries Service, NOAA, Smithsonian Institution, Post Office Box 37012, National Museum of Natural History, WC–57, MRC–153, Washington, DC 20013–7012, USA. E-mail: [email protected] 2Department of Biology, University of Victoria, PO Box 3080, Victoria, British Columbia, Canada V8W 3N5. E-mail: [email protected]; [email protected] 3Corresponding author. E-mail: [email protected] Abstract Symphurus maculopinnis n. sp., described on a single specimen (USNM 398820; 84.4 mm SL), was collected by a re- motely operated vehicle (ROV) exploring a hydrothermal vent area located at 561 m on Volcano–19, Tonga Arc, West Pacific (24°48.439' S, 177°0.009' W). This new species is distinctive and readily diagnosed from congeners by the follow- ing combination of characters: 1–2–2–2–1 pattern of interdigitation of dorsal proximal pterygiophores and neural spines (ID pattern), 14 caudal-fin rays, 3+6 abdominal vertebrae, 49 total vertebrae, 89 scales in a longitudinal row, 92 dorsal- fin rays, 77 anal-fin rays, blunt squarish snout, thick blind-side lips with conspicuous plicae, and conspicuous ocellated (sometimes partially) spots on posterior dorsal and anal fins. Among Symphurus, only S. ocellatus von Bonde, collected at deepwater locations off East Africa, features a similar ID pattern, 14 caudal-fin rays and spots on the posterior dorsal and anal fins. Symphurus maculopinnis differs distinctly from S. ocellatus in its lower and non-overlapping meristic fea- tures (49 vs. 54–56 total vertebrae; 92 vs. 97–103 dorsal-fin rays; and 77 vs. 85–89 anal-fin rays), its squarish (vs. pointed) snout, and thick, plicated blind-side lower lip (vs. thin, non-plicated blind-side lower lip). Additional specimens (N= 56) of S. maculopinnis observed and filmed in situ near active venting sites located between ca. 433-561 m on Volcano–19 provide the basis for behavioral and ecological information recorded for the species. Videotapes reveal one individual of S. maculopinnis featuring reversed (dextral) asymmetry from that typical (sinistral) for members of the Cynoglossidae. Specimens with reversed asymmetry are relatively rare in this family and this S. maculopinnis represents only the second known reversed individual among the approximately 42 species of deep-sea (>200 m) Symphurus. Key words: taxonomy, deep-sea flatfish, tongue sole, hydrothermal vents, volcanic arcs, seamounts, reversed asymmetry, species description, ocelli Introduction Exploratory expeditions along the Tonga and Kermadec Volcanic Arcs investigated various features of submarine volcanoes, hydrothermal vents and their associated faunas (e.g. Stoffers et al. 2006). Of particular interest during these expeditions was the discovery of symphurine tonguefishes associated with deepwater hydrothermal vents and other habitats on these undersea volcanoes (Tunnicliffe et al. 2010). One undescribed tonguefish species, Species B, observed on Volcano–19 in the Tonga Arc, was conspicuous in the possession of a single pigmented spot on both the posterior dorsal and anal fins. This pigmentation feature is rare among species of Indo–West Pacific Sym- phurus (Munroe unpubl. data), with only S. ocellatus von Bonde collected from deep waters in the western Indian Ocean having such spots on its dorsal and anal fins. A single specimen (now the holotype) of this undescribed species, collected at 561 m on Volcano–19 during a dive conducted by the ROV ROPOS, provides the basis for formal description of this species. Details of the expe- ditions including physico-chemical data of habitats where this specimen was collected and where other specimens of this species were observed, as well as ecological and behavioral observations for the new species, were provided in Tunnicliffe et al. (2010). Accepted by M.T. Craig: 8 Aug. 2011; published: 18 Oct. 2011 53 Material and methods The holotype (USNM 398820) is deposited in the fish collection of the United States National Museum. Descrip- tion of this species is based on counts and measurements from the holotype, with features of live pigmentation pro- vided by a photograph of the holotype prior to collection (Fig. 1) and photographs of additional specimens filmed in situ on Volcano–19 from a remotely operated vehicle (ROV). Comparative materials for other Indo-Pacific spe- cies of Symphurus are detailed in Munroe (1992), Krabbenhoft and Munroe (2003), Munroe (2006), Munroe and Hashimoto (2008), and Lee et al. (2009a). FIGURE 1. Holotype of Symphurus maculopinnis, n. sp. (now USNM 398820), photographed in situ just prior to collection by ROV ROPOS at 561 m on Volcano–19, Tonga Arc, West Pacific. Manipulator is holding a scoop net. Methods for counts and measurements and general terminology for systematics of tonguefishes follow those of Munroe (1998). Terminology for interdigitation patterns of proximal dorsal pterygiophores and neural spines (ID pattern) follow that of Munroe (1992). ID patterns, fin ray and vertebral counts were made from radiographs. Standard length (SL) and head length (HL) are used throughout. Measurements were made to the nearest 0.1 mm using either dial calipers or a dissecting stereo microscope fitted with a calibrated ocular micrometer. Morpho- metric features are expressed either as measurements in percentages of standard length, or percentages of head length. Pigmentation of alcohol-preserved fish is based on the holotype, which was originally fixed in 95% ethanol and then transferred and stored in 75% ethanol. Habitat descriptions and behavioral observations are based on fishes videotaped in situ and reported on by Tunnicliffe et al. (2010), with additional observations made from two fish appearing in a short video provided from the ROV ROPOS (Cruise Chief Scientist Dr. Ulrich Schwarz-Scham- 54 · Zootaxa 3061 © 2011 Magnolia Press MUNROE ET AL. pera) and edited by Jonathan Rose (University of Victoria; video available at http://ocean.si.edu/ocean-videos/ tonguefish-underwater-volcano-19). Size at maturity was determined from the stage of ovarian development in the female holotype following criteria outlined in Munroe (1998). Symphurus maculopinnis, new species Figures 1–7; Table 1 Symphurus species B. Tunnicliffe et al. 2010:4 (species recognition; bathymetric and ecological notes; genetic sequence data; distribution, abundance; color photographs). Holotype. USNM 398820, female, 84.4 mm SL, collected on Volcano–19 near Marker 40, Tonga Arc (24°48.439'S, 177°0.009'W), West Pacific Ocean, 561 m, collected with hand-held net (Sample Number R1048– 12) by ROV ROPOS directed by Anna Metaxas, 7 May 2007. FIGURE 2. Symphurus maculopinnis, n. sp. (Holotype USNM 398820; female, 84.4 mm SL), collected at 561 m on Volcano– 19, Tonga Arc, West Pacific. A. Ocular-side of alcohol-preserved specimen. B. Blind-side of same specimen. Diagnosis. Symphurus maculopinnis is distinguished from all other species of Symphurus by the combination of a 1–2–2–2–1 ID pattern, 14 caudal-fin rays, 3+6 abdominal vertebrae, 49 total vertebrae, about 89 scales in a longitudinal row, 92 dorsal-fin rays, 77 anal-fin rays, a blunt squarish snout, blind-side lower jaw with thick lip with conspicuous plicae, and by conspicuous ocellated (sometimes partially) black spots on the posterior dorsal and anal fins. Description. Morphological description based entirely on holotype (adult female, 84.4 mm SL; Figs. 1–5). A medium-sized species of Symphurus measuring to at least 100 mm SL [based on photographed specimens in Tun- nicliffe et al. (2010)]. ID pattern 1–2–2–2–1 (Figs. 3–4). Caudal-fin rays 14. Dorsal-fin rays 92. Anal-fin rays 76 (+1 fin ray missing). Pelvic-fin rays 4; posteriormost pelvic-ray connected to first anal-fin ray by delicate mem- NEW WESTERN PACIFIC TONGUEFISH Zootaxa 3061 © 2011 Magnolia Press · 55 brane. Total vertebrae 49; abdominal vertebrae 9 (3+6) (Fig. 4). Hypurals 5. Longitudinal scale rows about 89. Scale rows on head posterior to lower orbit 21. Transverse scale rows 45. Morphometrics (expressed as percentages of SL or HL; Table 1). Body moderately elongate (Fig. 2) with greatest body depth (29.6% SL) located in its anterior third (between anal-fin rays 10–25) and with gradual poste- rior taper. Preanal length slightly smaller than body depth. Head long, moderately wide, with squarish snout (Figs. 2A, 5); head length (21.6% SL) less than head width (25.6% SL; HW/HL = 1.20). Lower head lobe (12.7% SL) narrower than upper head lobe (16.2% SL); lower head lobe width less than postorbital length. Snout relatively broad with squarish anterior profile; snout length 18.1% HL; snout slightly longer than eye diameter. Dermal papil- lae conspicuously present on both ocular and blind sides of snout and head, but more numerous on blind-side head (Figs. 5A–B). Ocular-side snout and head with several short, vertical rows of dermal papillae as well as other TABLE 1. Morphometric features for holotype (USNM 398820) of Symphurus maculopinnis n. sp. and 19 S. ocellatus. SL in mm; characters 2–9 in % of SL; 10–17 in % of HL. S. maculopinnis S. ocellatus Character Holotype N=19 1. Standard length 84.4 75.6–120.5 2. Body depth 29.6 23.5–30.1 3. Preanal length 25.6 20.0–23.5 4. Head length 21.6 15.9–20.0 5. Head width 25.6 18.3–22.6 6. Postorbital length 13.5 10.5–13.7 7. Upper head lobe 16.2 9.9–15.6 8. Lower head lobe 12.7 7.4–11.9 9.