Vietnam Journal of Marine Science and Technology; Vol. 19, No. 4A; 2019: 175–181 DOI: https://doi.org/10.15625/1859-3097/19/4A/14597 https://www.vjs.ac.vn/index.php/jmst A new record of congrid eel, Bathycongrus bleekeri (Congridae) from Vietnam Quang Van Vo1,*, Hsuan-Ching Ho2, Hoa Hong Thi Tran1, Thao Thu Thi Le1, Thinh Cong Tran1 1Institute of Oceanography, VAST, Vietnam 2National Museum of Marine Biology & Aquarium, Taiwan *E-mail:[email protected] Received: 30 July 2019; Accepted: 6 October 2019 ©2019 Vietnam Academy of Science and Technology (VAST) Abstract Three specimens of Bathycongrus bleekeri were collected during the survey in 2015 and 2017. The newly recorded species is described herein, a small, moderately elongate species of Bathycongrus with head and body compressed; vertical fins without black mark; tail slender, attenuated, but not filiform; trunk length 1.2 times greater than head length; teeth small, conical, in about three-four rows on jaws, in a small triangular patch on vomer; 28-29 preanal vertebrae, total of 111-113 vertebrae; 26-28 preanal lateral-line pores. Additional data on the morphology and distribution of the species increases the total number of known species in the family Congridae in Vietnamese waters to twelve. Keywords: Bathycongrus bleekeri, Congridae, new record. Citation: Quang Van Vo, Hsuan-Ching Ho, Hoa Hong Thi Tran, Thao Thu Thi Le, Thinh Cong Tran, 2019. A new record of congrid eel, Bathycongrus bleekeri (Congridae) from Vietnam. Vietnam Journal of Marine Science and Technology, 19(4A), 175–181. 175 Vo Van Quang et al. INTRODUCTION Kamohara, 1938; Rhynchoconger ectenurus The Congridae is poorly known at the (Jordan & Richardson, 1909); Uroconger species level in the Indo-West Pacific, and a lepturus (Richardson, 1845) [8–10]. Based on composition list is proposed for this family [1], those works, the genus Bathycongrus is not in which genus Bathycongrus Ogilby 1898 only recorded in Vietnam. Karmovskaya (2011) [7] has one species Bathycongrus guttulatus described a new species belonging to genus (Günther, 1887) and an undescribed species. It Bathycongrus (Bathycongrus parviporus) from is difficult to identify the species in this genus, specimens collected in the coastal waters of because these eels possess very few distinctive Central Vietnam within the depth range 17-80 external characters. This genus in waters of the m and other new species is also described Indo-West Pacific was revised with seven valid (Ariosoma dolichopterum Karmovskaya, 2015) species being recognized for this ocean [2]. The which has been collected from specimens in authors suggested a key that permits the Vietnam [11]. The species composition of the differentiation of an Indo-West Pacific species family Congridae was supplemented by the within this genus according to a combination of description of new species and new records, in characters. Many new species for science are which eleven species are recognized in the being discovered; the five species are described Vietnamese waters. as new in Taiwan in 2018, including Bathycongrus bimaculatus, Bathycongrus MATERIALS AND METHODS graciliceps and Bathycongrus castlei [3], The present study is based on the material Bathycongrus albimarginatus and collected during investigations in July 2015 and Bathycongrus brunneus [4]. Recently, its March 2017. We collected three specimens; species composition was supplemented by the one specimen at the fish landing ground of My description of new species; the list recognized Tho commune, Phu My district, Binh Dinh 13 valid species in Indo-Pacific: Bathycongrus province, OIM (VNMN) Fi.01370 (156mm TL) aequoreus (Gilbert & Cramer, 1897); B. and two specimens at the fish landing ground bleekeri (Fowler, 1934); B. guttulatus of Tho Quang commune, Son Tra district, Da (Günther, 1887); B. macrocercus (Alcock, Nang city, OIM (VNMN) Fi.03701 (154 mm 1894); Bathycongrus macroporis (Kotthaus, TL); OIM (VNMN) Fi.03702 (148 mm TL) on 1968); B. odontostomus (Fowler, 1934); B. 26 March 2017. Three specimens are deposited retrotinctus (Jordan & Snyder, 1901); B. in the Museum of Oceanography (Institute of wallacei (Castle, 1968); B. trimaculatus Oceanography), Nha Trang, Vietnam (OIM). Karmovskaya & Smith, 2008; B. longicavis Counts, measurements, and bone Karmovskaya, 2009; B. parapolyporus terminology are as in [3, 12]. All measurements Karmovskaya, 2009; B. unimaculatus are in mm, and unless otherwise stated, lengths Karmovskaya, 2009; B. parviporus are total lengths. Vertebral counts were taken Karmovskaya, 2011 [1, 5–7], and five species directly from digital radiographs, while tooth newly described in 2018 from Taiwan; counts were taken from the specimens. Counts including Bathycongrus bimaculatus; of sensory pores were made under the light Bathycongrus graciliceps; Bathycongrus microscope. The general arrangement of the castlei; Bathycongrus albimarginatus and head pores is shown in Fig. 1. Head pores vary Bathycongrus brunneus [3, 4]. in size, many of them are enlarged, including In Vietnamese waters, 9 species of the supraorbital pore (including terminal ethmoidal family Congridae have been recorded: pore); infraorbital pore; preopercular- Ariosoma anago (Temminck & Schlegel, mandibular pore (mandibular pores and 1846); Bathymyrus simus Smith, 1965; Conger preopercular pores); ST - supratemporal pore. cinereus Rüppell, 1830; Conger conger The very first pore, which is at the junction of (Linnaeus, 1758); Conger japonicus Bleeker, the lateral-line and supratemporal canals and 1879; Gnathophis nystromi (Jordan & Snyder, usually enlarged, is counted as the first pore of 1901); Parabathymyrus macrophthalmus lateral-line series. The number of lateral-line 176 A new record of congrid eel pores was counted when available; predorsal, (5.6–5.9) in TL; tail length ~1.5 in TL; depth at prepectoral and preanal pores are counted to head 5.3 (5.2–5.3) in PAL, width at head 5.6 verticals of just before first dorsal fin ray, upper (5.4–5.7) in PAL. Snout length 4.8 (4.6–5.0) in pectoral fin base and end of the anus (or just HL; eye diameter 4.5; interorbital width 10.0 before first anal fin ray), respectively [3, 5]. (9.7–10.6); upper jaw 3.3; gill opening width Jaw teeth include teeth on maxilla and 7.5 (7.3–7.7); interbranchial width 5.0 (4.9– mandible in multiserial bands. Intermaxillary 5.0); pectoral-fin length 3.7 (3.6–3.7). teeth are moderately enlarged, in 2 to several Body is moderately elongate, laterally rows separated from maxillary and vomerine compressed through the entire length, oval in teeth, mostly exposed when the mouth closed. cross section, becoming more compressed Vomerine teeth are highly variable in size, posteriorly; tip of the tail is rightly attenuated; number and arrangement, although some are anus is slightly behind anterior third of total quite similar. Vertebral counts, including the length (fig. 2). Dorsal fin begins over the preanal and total vertebrae have long been used middle of appressed pectoral fin, is continuous to distinguish eel species. The proportions of around the tip of the tail with caudal and anal head length, predorsal length, preanal length, fins. Anal fin begins immediately behind the and trunk length and other proportions of the anus. Pectoral fin is well developed, pointed head are used for description. Because the tip distally with narrow base. Gill opening is of the tail is usually damaged and regenerated, relatively large, about the same size of the eye, the total length is not always accurate [3]. its upper end is nearly opposite to the upper The identification and comparison of pectoral fin base; interbranchial space is morphology of specimens are based on broader than gill opening and eye. Head is documents [2–7, 11–15]. relatively large, its length 16.6–18.3% TL, The following abbreviations are used TL - deepest about midway between gill opening total length; HL - head length, PAL - preanal and tip of the snout, descending forward from length; SO - supraorbital pore; IO - infraorbital that point. Snout is short, broadly pointed on pore; POM - preopercular-mandibular pore; ST dorsal view, its length 1.0–1.3 times of eye - supratemporal pore. diameter, projecting beyond the lower jaw; it is longer than snout; fleshy part of snout projects RESULTS anterior beyond the anterior end of the Family Congridae intermaxillary tooth patches; rictus is nearly Genus Bathycongrus Ogilby, 1898 below posterior half of the eye. Upper jaw is Bathycongrus Ogilby, 1898: 292; type with flange greatly reduced; lower jaw is with species Congromuraena nasica Alcock, 1893 downturned flange. Tongue is free, long, and [12]. broad. Anterior nostrils are tubular, near a tip Bathycongrus bleekeri Fowler, 1934 of the snout, directly ventrolaterally. Posterior Vietnamese name: Cá Chình đuôi nhọn sọc nostrils are elliptical, with a slightly raised rim, bạc. in front of mid-eye level. Upper lip is with a Bathycongrus bleekeri Fowler, 1934: 272 shallow, free, upturned flange, beginning at (type locality: Utara Pt., Bongo Island, southern second infraorbital pore and ending below Mindanao, Philippines); Karmovskaya & middle of the eye. Lower lip is with a well- Smith, 2008: 30; Karmovskaya, 2009: 150; developed downturned flange. Lateral-line is Karmovskaya, 2011: 417; Smith & Ho, 2018: complete, first pore on each side is slightly 126–129. enlarged, the canal is extended to caudal fin Description. Proportional measurements base; 5–6 pores before the dorsal fin origin, 3–4 and meristics are provided in table 1. pores before pectoral fin base, 26–28 pores Head length 2.0 (1.9-2.1) in PAL, 5.8 (5.5– before the anal fin origin, 90+ –93+ total pores, 6.0) in TL; preanal length 2.9 (2.8–3.0) in TL; but this number may be a bit more than 100. 8 predorsal length 1.9 in PAL, 5.3 (5.2–5.4) in predorsal vertebrae; 28–29 preanal vertebrae; TL; trunk length 2.0 (1.9–2.1) in PAL, 5.8 total of 111–113 vertebrae (fig.