Review of the arrowtooth eel genera Dysomma and Dysommina in Taiwan, with the description of a new species (Anguilliformes: Synaphobranchidae: Ilyophinae) Author Ho, Hsuan-Ching Author Smith, David G. Author Tighe, Kenneth A. text Zootaxa 2015 4060 1 86 104 journal article 39199 10.11646/zootaxa.4060.1.12 ca0b84ea-10e9-4bc9-9fa7-e80cf743106b 1175-5326 237500 DCE83F63-6CBE-4166-884F-347DF0BEBB62 Dysomma dolichosomatum Karrer, 1983 Figs. 4 A–B; Table 1 Dysomma dolichosomatum Karrer, 1983 :93 ( type locality: Madagascar , 22°25'S , 43°04.5'E , 550–555 m ). Robins & Robins, 1989 :249 . Chen & Mok, 2001 :79 . FIGURE 4. Dysomma dolichosomatum Karrer, 1983 . NMMB-P11130. A. 269 mm TL.B. 231 mm TL. Collected from Dong-gang fishing port. Specimens examined. Collected from Fong-gang, SW Taiwan : NMMB-P2861 (1 spec., 242 mm TL), 8 Nov. 2001 . Collected from Dong-gang fishing port, SW Taiwan : NMMB-P9098 (1, dry), 13 Jun. 2008 . NMMB-P9241 (1, 349), 18 Sep. 2008 . NMMB-P11121 (6, 209–312), 16 Jul. 2009 . NMMB-P11130 (2, 231–269), 13 Sep. 2010 . NMMB-P12066 (1, 336), 28, Jan. 2011 . NMMB-P13794 (1, 197), 21 Jul. 2011 . NMMB-P14189 (4, 166–301), 20 Oct. 2011 . NMMB-P15568 (2 of 4, 218–294), 25 Oct. 2011 . NMMB-P16134 (1, 189), 9 Feb. 2012 . NMMB- P16404 (4, 264–320), 28 Jan. 2012 . NMMB-P16422 (1, 357), 21 Feb. 2012 . NMMB-P17820 (1, 357), 2 Nov. 2012 . NMMB-P17881 (1, 263), 25 Jan. 2012 . NMMB-P18083 (1, 336), 7 Sep. 2012 . NMMB-P21733 (2, 215– 221), 18 Feb. 2011 . NMMB-P21799 (1, 227), 7 Nov. 2013 . NMMB-P21928 (1, 343), 1 Nov.2014 . NMMB-P22126 (1, 242), 12 Dec. 2013 . USNM 270682 (2, 172–187), 23 Nov. 1969 . USNM 398567 (1, 317), 10 Nov. 2009 . USNM 401019 (1, 197), 26 Feb. 2011 . USNM 401036 (1, 345), 8 Nov. 2009 . Other localities. Madagascar : MNHN 1979-0004, holotype , 22°25'1.2"S , 43°4'4.8"E , 550–555 m , 27 Nov. 1973 . Philippines : MNHN 1978-0717, paratype , 14°1'1.2"N , 120°22'1.2"E , 223 m , 21 Mar. 1976 . Solomon Islands : MNHN 2006-0734 (1, 203), 8°24'28.8"S , 159°28'22.8"E , 105–897 m , 24 Oct. 2004 . Diagnosis. No pectoral fin; dorsal-fin origin about 0.8–1 HL behind gill opening, predorsal length 16.5–19.1% TL; anus posterior, about 1.5 time of HL behind gill opening, preanal length 23.3–28.6% TL; trunk long, trunk length 14.3–17.7% TL; two intermaxillary teeth; 2 irregular rows of small blunt teeth on upper jaw; 2 or 3 (mainly 3) compound teeth on vomer; single row of 4 or 5 small compound teeth followed by 1 or 2 irregular rows of small blunt teeth on lower jaw; short cirri on surfaces of chin and jaws; head pores: IO 4, SO 3, M 6 (1 with 7), POP 1, AD1, F 0, ST 0; lateral-line pores large, prepectoral 5 or 6, total 9–11, the last at slightly beyond the gill opening posteriorly; MVF 18-27-153, total vertebrae 146–156. Body light pinkish to light grayish dorsally when fresh with a black margin at posterior portion of anal fin; light brownish to grayish when preserved. Distribution. Indo-west Pacific off Madagascar , Taiwan , Philippines , and Solomon Islands at depth 105– 897 m . Remarks. This species is common in the by-catch in Taiwan . It is usually collected by midwater trawlers together with many mesopelagic fishes, which would indicate pelagic living. However, many specimens are also found to feed on polychelids, a demersal shrimp family. Dysomma dolichosomatum is the only species found to possess one preopercular pore and a very short lateral line, with only 9–11 pores, among all Taiwanese species. It is similar to D. brevirostre , D. muciparus and D. tridens in lacking a pectoral fin. It differs from D. brevirostre by having tiny papillae on the head and snout (vs. large papillae and ridges) and total vertebrae 146–156 (vs. 195–205 in Robins & Robins, 1989 ); from D. muciparus by having trunk 1.4–1.9 times in head length (vs. less than 1 time in head length) and 146–156 total vertebrae (vs. 153–157); and from D. tridens by having 2 intermaxillary teeth (vs. three large compressed teeth) and by having 146–156 total vertebrae (vs. 175). Our specimens have a broader range of total vertebrae (146–156) compared to 151–152 reported for the types by Karrer (1983) . One 312 mm specimen out of NMMB-P 11121 had a relatively long predorsal measurement (23.4 % of TL) and high predorsal vertebral count (25 vertebrae). While it is possible that this specimen may represent a different species, the close correspondence of all other counts and measurements with the other specimens of D. dolichosomatum from Taiwan indicates that it is probably a specimen with an aberrant dorsal origin.