Conger cinereus Rüppell, 1871

Smith, David G. & Ho, Hsuan-Ching, 2018, Review of the congrid eel genus Conger (Anguilliformes: Congridae) in Taiwan, Zootaxa 4454 (1), pp. 168-185 : 170-173

Conger cinereus Rüppell, 1871

Figs. 1 , 2A , 3A ; Table 1

Conger cinereus Rüppell in Klunzinger, 1871:607 (Type locality: Red Sea. Holotype: SMF 766 [not an independent species description, but a new genus applied to Conger assigned to Muraena cinerea Forsskål, 1775 , a muraenesocid]). First available usage as Conger cinereus Rüppell in Klunzinger, 1871 ( Fricke, 2008:15) . Chen & Weng, 1967:50; Chen, 1969:132; Shen, 1984:112; Chen & Yu, 1986:252; Shen et al., 1993:116; Shao et al., 2008:239; Ho et al, 2015:146.

Specimens examined. 55 specimens, 53‒945 mm TL. * ASIZP 54973 (1, 407), Hengchun , Pingtung, southern Taiwan, 28 Dec. 1977 . * ASIZP 56623 (1, 468), Hengchun , Pingtung, 1 Oct. 1975 . * ASIZP 56903 (1, 383), Hengchun , Pingtung, 25 May 1975 . * ASIZP 57461 (1, 93), Lanyu , Taitung, southeastern Taiwan, 20 Sep. 1979 . * ASIZP 57701 (2, 94‒128), Mao-pi-tou, Pingtung, 1 Aug. 1969 . * ASIZP 57962 (1, 283), Dongsha Atoll (Pratas Atoll), South China Sea , 7 May 1990 . * ASIZP 58008 (1, 104), Longken , Pingtung, 25 Mar. 1988 . * ASIZP 58985 (1, 165), Huawan , Pingtung, 14 Mar. 1990 . * ASIZP 60201 (1, 95), Mao-pi-tou, Pingtung, 25 Apr. 1975 . * ASIZP 63600 (1, 565), Daxi , Yilan, northeastern Taiwan, 29 Sep. 2000 . ASIZP 69766 (1, ca. 600) and ASIZP 69770 (1, ca. 600), Changbin , Taitung, 6 May 2005 . NMMB-P1358 (2, 182+‒220), Wan-li-tong, Pingtung, 22 Apr. 1968 . * NMMB-P1396 (1, 217), O-luan-bi, Pingtung, 15 Sep. 1966 . NMMB-P1397 (1, 155), Wan-li-tong, Pingtung, 22 Apr. 1968 . * NMMB-P1476 (1, 257+), Hsiao-liu-chiou, Pingtung, 16 Mar. 1966 . * NMMB-P1477 (2, 199+‒257), Wan-li-tong, Pingtung, 17 May 1966 . NMMB-P3012 (1, 134), no data. NMMB-P3797 (1, 155), * NMMB-P4458 (5, 71‒338+), Hsiao-liu-chiou, Pingtung, 20 Mar. 1973 . NMMB-P24265 (1, 366+), Taiwan , no other data. NMMB- P27759 (1, 945), NMMB-P27760 (1, 800), Cheng-gong , Taitung, 22 Jun. 2017 . USNM 311259 (1, 455), east side of east line of rocks on point just southwest of Yeh-liu , Taipei, northern Taiwan, 0‒5 m , 18 May 1968. USNM 311260 (8, 83‒253+), cut between large outstanding rock and Ch'uan-fan-shih, Pingtung, 0‒6 m , 23 Apr. 1968. USNM 311266 (1, 106), rocky headland northwest of swimming beach of Sha-tao, 0‒5 m, 5 May 1968. USNM 311269 (1, 238), southwest end of Taiwan, approximately 2 km southwest of Ta-fan-lieh, 0‒2 m, 5 May 1968. USNM 311270 (1, 53), southeast tip of Taiwan, Pacific Ocean side, 0‒2 m , 27 Apr 1968. USNM 311272 (1, 158), southwest end of Taiwan, tidal flat at Ta-fan-lieh, 1 m, 25 Apr. 1968. USNM 311273 (1, 83), southwest shore just off Ch'uan-fan-shih, 8‒9 m, 3 May 1968. USNM 311274 (1, 88), southwest shore just off Ch’uan-fan-shih, 5‒6 m, 28 Apr 1968. USNM 311277 (1, 423+), southwest end of Taiwan, approximately 2 km southwest of Ta-fan-lieh, 0‒0.8 m, 26 Apr 1968 USNM 311284 (3, 106‒386), rocky shore just south of Chin-chiao-wan, south end of Taiwan , 8 May 1968. USNM 311287 (8, 87‒206), bay between K’en-ting and Ta-yuan Shan, 5‒9 m, 1 May 1968.

Diagnosis. Pores present behind eye. Sixth IO pore above and less than one pore diameter behind rictus. Rictus under or slightly behind posterior margin of eye ( Fig. 2A ). DFO over middle of pectoral fin, predorsal length less than 15% TL, preanal length 30.7‒33.8 % TL. Black streak below eye parallel to upper lip. Vertebrae 140‒148 in Taiwan [139‒146 from elsewhere].

Description. See Table 1 for morphometric data. Lateral-line pores: prepectoral usually 4‒6 (1 with 8); predorsal 6‒10; preanal 36‒40; total 130‒142. Head pores ( Fig. 2A ): SO 3, IO 5+1+2‒3 (rarely 5+1+0‒1; 5 on upper jaw + 1 behind rictus + 0‒3 behind eye), POM 10 (rarely 9, 7 on lower jaw, 3 behind rictus), ST 1. Vertebrae: predorsal 9‒11; preanal 36‒39; total 140‒148; MVF 10-38-143.

DFO over middle of pectoral fin. Angle of rictus under posterior margin of eye, 6th IO pore above and less than one pore diameter behind rictus. Maxillary teeth none to few in inner row of upper jaw and up to 15 in that of lower jaw ( Fig. 3A ). Color medium to dark brown; black margin on dorsal and anal fins; a dark streak below eye parallel to upper lip; dark spot often present on pectoral fin. In life, commonly shows a pattern of dark bars on body at night, but these usually do not remain in preservative.

Maximum size 1400 mm TL ( Allen & Erdmann, 2012).

Distribution. Widespread in the Indo-west Pacific Ocean, from the coast of Africa and the Red Sea to the islands of the central Pacific. Commonly found in shallow waters near coral reef areas.

Remarks. Conger cinereus was described by Rüppell (1830) from the Red Sea. Although his text and figure clearly refer to the species we now know as Conger cinereus , he treated it as a new combination for what we now call Muraenesox cinereus (Forsskål) , and not as a new species. The name dates from 1871, when Klunzinger gave an explicit description and credited the name to Rüppell.

This is the most distinctive species in several characters. The jaw is longer in relation to the eye than in the other species, with the rictus beneath the posterior margin of the eye. This also alters the position of the 6th IO pore, which is located above and immediately behind the rictus. In other species, the rictus is well before the posterior margin of the eye, and the 6th IO pore is well behind the rictus at about the same horizontal level. There are usually 10 POM pores, whereas the other species in Taiwan typically have 9. The DFO is more anterior, over the middle of the pectoral fin, with a correspondingly lesser predorsal length. The preanal length is also less than in the other species. The oblique stripe below the eye is unique to C. cinereus , as is the barred color pattern it sometimes shows. It is the species most commonly found in shallow water on coral reefs.

Kanazawa (1958) reported two rows of maxillary teeth in this species, but we found only one row with a few additional teeth around the anterior portion of the upper jaw, whereas up to 15 in that of the lower jaw.

Kanazawa (1958) divided this species into two subspecies, Conger cinereus marginatus Valenciennes in Eydoux & Souleyet from Hawaii and Conger cinereus cinereus from elsewhere. Recent genetic data suggest that there may be additional subdivisions within C. c. cinereus (Smith, unpub. data). Further studies are needed to determine the taxonomic structure of Conger cinereus .

Figures

FIGURE 1. A‒B. Conger cinereus Rüppell, 1871, NMMB-P4458, 338+ mm TL. Bars indicate origins of dorsal fin (above) and anal fin (below). C. NMMB-P27759, 945 mm TL.

FIGURE 2. Line drawings demonstrating the arrangement of head pores of two species. A. C. cinereus. B. C. myriaster. Bar indicates the ST pore.

FIGURE 3. Demonstration of jaw tooth pattern of five Conger species in Taiwan. A. C. cinereus, from NMMB-P24265. B. C. jordani, from NMMB-P24766. C. C. macrocephalus, NMMB-P15401. D. C. myriaster, NMMB-P6392. E. C. philippinus, NMMB-P22425. Note that the numbers of principal teeth are not counted from the specimens.