Species Diversity 17: 169–172 25 November 2012 Record of a Rare Ophidiid Fish, Barathrites iris (Actinopterygii: Teleostei: Ophidiiformes), from off Southern Japan Shinpei Ohashi1,3, Hisashi Imamura2 and Mamoru Yabe2 1 Chair of Marine Biology and Biodiversity (Systematic Ichthyology), Graduate School of Fisheries Sciences, Hokkaido University, 3-1-1 Minato-cho, Hakodate, Hokkaido 041-8611, Japan E-mail: [email protected] 2 Laboratory of Marine Biology and Biodiversity (Systematic Ichthyology), Research Faculty of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido 041-8611, Japan 3 Corresponding author (Received 14 November 2011; Accepted 23 March 2012) Two specimens of a rare ophidiid fish, Barathrites iris Zugmayer, 1911, were collected from the abyssal Pacific Ocean, off Kagoshima Prefecture, southern Japan. They agree with the diagnosis of Barathrites in having two pelvic-fin rays, five to six long gill rakers on the anterior gill arch, and a small head (33.5–33.8% of pre-anal-fin length) and eye (1.6–1.8% standard length, SL). Additionally, they can be separated from B. parri Nybelin, 1957, the only other known species of the genus, by their lack of basibranchial tooth patches, smaller eye (10.7–12.3% head length), and shorter pre-dorsal-fin region (17.1–18.9% SL). Previously B. iris was said to differ from B. parri in the number of branchiostegal rays (six versus seven, respectively), but one of the present specimens of B. iris (413 mm SL) has seven branchiostegal rays on the left side and six on the right. Earlier workers have suggested the occurrence of Barathrites in the Pacific Ocean, but no documented records from this ocean appear to exist. This study confirms the occurrence of Barathrites and its type species B. iris in the Pacific Ocean. Key Words: Pacific Ocean, Japan, Barathrites iris, Ophidiidae, abyssal fish. Lagler (1958). Counts of basibranchial tooth patches and gill Introduction rakers, and the pre-dorsal-fin and pre-anal-fin lengths fol- low Nielsen et al. (1999). Vertebrae and dorsal-, anal-, and When the senior author joined a deep-sea workshop caudal-fin rays were counted from radiographs. Body depth held at the National Museum of Nature and Science, Tokyo was measured at the dorsal-fin origin and at the anal-fin ori- (NSMT) (1–10 February 2010), he had the opportunity gin. Standard length and head length are abbreviated as SL to examine two ophidiid specimens collected from abys- and HL, respectively. sal depths off Kagoshima Prefecture, southern Japan. They proved to belong to the rare genus Barathrites Zugmayer, Barathrites Zugmayer, 1911 1911, which includes two valid species, Barathrites iris Zug- [New Japanese name: Kogashira-ashiro-zoku] mayer, 1911 and Barathrites parri Nybelin, 1957. The ge- neric assignment was based on the two pelvic-fin rays, five Barathrites iris Zugmayer, 1911 to six developed gill rakers on the first arch, and small head [New Japanese name: Kogashira-ashiro] (33.5–33.8% of pre-anal-fin length) of the present speci- (Figs 1–2; Tables 1–2) mens (Nielsen et al. 1999). More precisely, they were identi- fied as B. iris, which can be distinguished from B. parri by Barathrites iris Zugmayer, 1911: 193 (type locality: south- the absence in the former of basibranchial tooth patches as west of Azores, 31°44′N, 42°39′W); Belloc 1949: 14, well as a smaller eye and a shorter pre-dorsal-fin region. The pl. 3 (list of type specimens); Nybelin 1957: 282, pl. 6 two species have been reliably reported only from tropical (key and description, off Surinam, Atlantic); Cohen and and subtropical regions of the Atlantic Ocean (Nielsen et al. Nielsen 1978: 25 (short description, tropical Atlantic and 1999; Mincarone et al. 2008). This study confirms the occur- Pacific?); Nielsen 1986: 1159 (key and short description, rence of Barathrites iris in the Pacific Ocean, with a descrip- northern mid-Atlantic); Arruda 1997: 109 (list, southwest tion of the specimens. of Azores); Nielsen et al. 1999: 53 (key and list, Atlantic); Nielsen and Robins 2003: 968 (key and list, Atlantic); Garrido-Linares and Acero P. 2006: 293 (list, Atlantic). Methods Barathrites abyssorum Roule, 1916: 17 (type locality: Mo- naco Trench, Atlantic); Belloc 1949: 14 (list of type speci- Counts and measurements mainly follow Hubbs and mens); Nybelin 1957: 284, 333 (key and description, © 2012 The Japanese Society of Systematic Zoology 170 Shinpei Ohashi et al. Fig. 1. Barathrites iris, NSMT-P 98868, 230.2 mm SL, Pacific Ocean off Kagoshima Prefecture, southern Japan. Table 1. Counts and measurements of Barathrites iris. NSMT-P 98868 (n=2) Standard Length (mm) SL 413.0 230.2 Counts Dorsal-fin rays 111 110 Caudal-fin rays 8 7 Anal-fin rays 79 77 Pectoral-fin rays 22 23 Pelvic-fin rays 2 2 Precaudal vertebrae 19 18 Total vertebrae 63 63 Basibranchial tooth patches 0 0 Long gill rakers on anterior gill arch 5 6 Pseudobranchial filaments 2 2 Branchiostegal rays 6 (right), 7 (left) 6 (both sides) Measurements in % SL Head length 14.8 14.9 Body depth at dorsal-fin origin 16.6 13.1 Body depth at anal-fin origin 19.3 16.2 Upper-jaw length 6.1 6.5 Length of snout 3.1 3.2 Horizontal eye diameter 1.6 1.8 Interorbital width 5.4 4.6 Postorbital length 10.6 9.5 Pre-anal-fin length 44.0 44.0 Pre-dorsal-fin length 17.1 18.9 Length from base of pelvic fin to anal-fin origin 36.1 35.5 Length of pectoral fin 11.5 14.6 Length of pelvic fin 7.1 8.5 Table 2. Comparison of three morphometric characters between the present Japanese specimens and two species of Barathrites from the Atlantic Ocean. Present specimens B. iris* B. parri* NSMT-P 98868 Holotype Nontype Holotype Standard length (mm) 413 230 221 208 233 Horizontal eye diameter (% HL) 10.7 12.3 11.4 11.7 14.6 Pre-dorsal-fin length (% SL) 17.1 18.9 18.1 18.8 21.5 Body depth at anal-fin origin (% SL) 19.3 16.2 15.4 16.3 18.9 * Data from Nybelin (1957). Monaco Trench, Atlantic); Cohen and Nielsen 1978: 25 230.2–413.0 mm SL, off eastern coast of Kagoshima Pre- (discussion of synonymy with Barathrites iris). fecture, southern Japan, Pacific Ocean (31°32.15′N, 133°43.2′E–31°33.13′N, 133°44.14′E), 4,856–4,864 m Material examined. NSMT-P 98868, 2 specimens, depth, R/V Hakuho-maru, cruise number KH-02-03, station Barathrites iris from off Southern Japan 171 dark. Distribution. Known from southwest of the Azores and off Surinam, Atlantic Ocean, at depths of 3,465–5,044 m (Zugmayer 1911; Nybelin 1957; Nielsen et al. 1999), and off Kagoshima, southern Japan, Pacific Ocean at a depth of 4,856–4,864 m (this study; Fig. 2). Remarks. The present two specimens collected off Japan agree with the generic characters of the genus Barath- rites indicated by Nielsen et al. (1999) in having two pelvic- fin rays, five to six long gill rakers on the anterior gill arch, and a small head (33.5–33.8% of pre-anal-fin length) and eye (1.6–1.8% SL). Nielsen et al. (1999) recognized that the two valid species of Barathrites, B. iris and B. parri, are distinguishable from each other by the basibranchial tooth patches (absent in B. iris vs present in B. parri) and the number of branchiostegal rays (six vs seven, respectively). Additionally, these species differ from each other in the horizontal eye diameter (11.4– 11.7% vs 14.6% HL), pre-dorsal-fin length (18.1–18.8% Fig. 2. Sampling locality of Barathrites iris (indicated by a circle). vs 21.5% SL), and body depth at the anal-fin origin (15.4– 16.3% vs 18.9% SL, respectively) (Nybelin 1957). The larger of the two present specimens (413.0 mm SL) does not fit this number TH-1, 15 September 2002. concept of B. iris because it has asymmetrical branchiostegal Diagnosis. A species of Barathrites with no basibran- rays (six on the right, seven on the left) and a deeper body chial tooth patches, a small eye (horizontal eye diameter (body depth 19.3% SL) (Table 2). However, its other features 10.7–12.3% HL), and a short pre-dorsal-fin region (pre- [absence of basibranchial tooth patches, a small eye (hori- dorsal-fin length 17.1–18.9% SL). zontal eye diameter 10.7% HL), and a short pre-dorsal-fin Description. Counts and measurements are given region (pre-dorsal-fin length 17.1% SL)] agree with those in Table 1. Body elongate and compressed. Head short, its of B. iris. Therefore, we consider the differences between the length 33.5–33.8% of pre-anal-fin length. Snout rounded. two specimens (number of branchiostegal rays and body Two pairs of nostrils; anterior one small without fleshy depth) as manifestations of intraspecific variation. raised rim, situated on anterior margin of snout; posterior Although Cohen and Nielsen (1978) suggested the oc- one larger, situated at midpoint between anterior nostril and currence of Barathrites in the Pacific Ocean, and Nielsen et anterior margin of eye. Mouth relatively small, subterminal; al. (1999) also suggested that Barathrites iris might occur in maxilla slightly extending beyond posterior margin of eye. the Pacific and the Indian oceans, they did not refer to any Vomerine and palatine with small granular teeth. Vomerine documented records. This study confirms the occurrence of tooth patch triangular.