Bathycongrus bleekeri Fowler, 1934

Smith, David G. & Ho, Hsuan-Ching, 2018, The congrid eel genus Bathycongrus of Taiwan, with descriptions of three new species (Anguilliformes: Congridae), Zootaxa 4454 (1), pp. 118-146 : 126-129

Bathycongrus bleekeri Fowler, 1934 (New record)

English name: Bleeker’s short-tail conger

Figs. 3B , 4A–D ; Tables 1–6

Bathycongrus bleekeri Fowler, 1934:272 (type locality: Utara Pt., Bongo Island, southern Mindanao, Philippines). Karmovskaya & Smith, 2008:30. Karmovskaya, 2009:150. Karmovskaya, 2011:417.

Specimens examined. NMMB-P21654 (1, 168), 27 Aug. 2008; NMMB-P25988, (1, 185), 15 Apr. 2017; NMMB- P26214, (1, 177), 16 Jun. 2017; NMMB-P27744 (1, 140.7), 10 Nov. 2017; all collected from off Dong-gang , Pingtung, SW Taiwan .

Diagnosis. A small, moderately elongate species of Bathycongrus with head and body compressed; vertical fins without black mark; tail slender, attenuate, though not filiform; trunk 1.4 times head length; teeth small, conical, in about four rows on jaws, in an elongate triangular patch on vomer; preanal vertebrae 27–28, precaudal vertebrae 34–37, total vertebrae 107–113; preanal lateral-line pores 25–26.

Description. Proportional measurements and meristics are provided in Tables 4–5. Head length 2.3–2.4 in PAL, 6.2–6.4 in TL; preanal length 2.7 in TL; predorsal length 2.0– 2.1 in PAL, 5.4–5.7 in TL; trunk length 1.7–1.8 in PAL, 4.7–4.8 in TL; tail length ~ 1.6 in TL; depth at head 6.1–6.8 in PAL, width at head 7.6–8.9 in PAL. Snout length 4.0– 4.2 in HL; eye diameter 4.7–5.5; interorbital width 6.7–7.3; upper jaw 2.7–2.9; gill opening width 3.5–7.1; interbranchial width 4.7–5.7; pectoral-fin length 2.9–3.4.

Body moderately elongate, laterally compressed through entire length, oval in cross section, becoming more compressed posteriorly; tip of tail moderately attenuate; anus slightly behind anterior third of total length. Dorsal fin begins over middle of appressed pectoral fin, continuous around tip of tail with caudal and anal fins. Anal fin begins immediately behind anus. Pectoral fin well developed, pointed distally with narrow base. Gill opening relatively large, about same size as eye, its upper end nearly opposite the upper pectoral-fin base; interbranchial broader than gill opening and eye.

Head relatively large, its length 15.5–16.1% TL, deepest about midway between gill opening and tip of snout, tapering anteriorly from this point; snout short, broadly pointed on dorsal view, its length 1.1–1.3 times of eye diameter, projecting beyond lower jaw; lower jaw longer than snout; fleshy part of snout projecting anteriorly beyond anterior end of intermaxillary tooth patch; rictus nearly below posterior half of eye. Upper jaw with flange greatly reduced; lower jaw with downturned flange. Tongue free, long, and broad.

Anterior nostril tubular, near tip of snout, directed ventrolaterally. Posterior nostril elliptical, with a slightly raised rim, in front of mid-eye level. Upper lip with a shallow, free, upturned flange, beginning at second infraorbital pore and ending below middle of eye. Lower lip with a well-developed downturned flange. Tongue free, long, and broad.

Lateral-line complete, first pore on each side slightly enlarged, the canal extended to caudal-fin base; 3–4 pores before pectoral-fin base, 5–6 pores before dorsal-fin origin, 25–26 pores before anal-fin origin, 90+–93+ total pores, assumable a bit more than 100.

Head pores vary in size, mostly enlarged ( Fig. 4E ); supraorbital canal with 3 pores, the first (ethmoidal pore) on ventral side of tip of snout, just ahead of lip, the second enlarged, about twice the size of first, and immediately in front of anterior nostril, the third greatly enlarged and immediately above anterior nostril, about same size as anterior nostril. Infraorbital canal with 5 pores, first 3 enlarged; the first at posterodorsal corner of anterior nostril; the second to fourth above the flange; the third below between posterior nostril and eye, the fourth below anterior margin of eye, and the fifth moderately large and behind rictus, at mid-eye level; no pores behind eye. Preoperculomandibular canal with 10 pores, 7 in mandibular section and 3 in preopercular; first pore very small, near anterior tip of lower jaw, the third greatly enlarged, the seventh behind rictus. Supratemporal commissure with no pore.

B. bimaculatus sp. nov. B. bleekeri B. castlei sp. nov. HT Types TL (mm) 163 157–190 (n=5) 168–185 (n=3) Trunk/HL 1.3 1.3–1.5 1.3–1.4 %TL HL 15.4 15.0 (14.3–15.7) 15.8 (15.5–16.1) PAL 35.3 36.0 (35.3–37.2) 36.9 (36.8–36.9) Predorsal 17.7 17.6 (17.3–17.9) 18.2 (17.7–18.5) Trunk 19.9 21.0 (19.9–22.5) 21.0 (20.7–21.4) Tail 64.7 64.0 (62.8–64.7) 63.1 (63.1–63.2) %PAL Head length 43.7 41.8 (39.6–43.7) 43.0 (42.1–43.8) Predorsal 50.1 49.0 (46.4–50.1) 49.4 (47.9–50.2) Head depth 17.4 17.0 (15.0–18.1) 15.8 (14.6–16.5) Head width 10.1 11.3 (10.1–12.1) 12.1 (11.7–13.2) %HL Snout 23.9 24.5 (23.2–26.7) 245. (23.9–25.2) Eye 17.1 19.4 (17.1–21.8) 20.1 (18.2–21.5) Interorbital 15.1 14.9 (13.4–16.2) 14.2 (13.7–14.9) Upper jaw 35.9 37.2 (35.9–39.7) 35.9 (35.1–37.2) Gill opening 12.0 12.8 (19.7–16.2) 20.1 (14.0–28.2) Isthmus 22.3 22.7 (19.7–25.9) 19.6 (17.7–21.5) Pectoral fin 27.9 32.8 (27.9–37.5) 31.7 (29.1–35.0)

HT Types NT 328 1.6 240–350+ (n=6) 1.4–1.6 199 (n=1) 1.6 13.5 15.6 35.1 21.6 64.9 13.6 (13.5–13.7) 35.6 (35.1–36.0) 16.3 (15.6–16.7) 22.0 (21.6–22.4) 64.4 (64.0–64.9) 13.5 35.7 15.0 22.2 64.3 38.5 45.2 12.4 11.0 39.1 (37.8–41.3) 45.8 (44.5–46.5) 12.7 (11.4–14.0) 11.0 (9.4–12.5) 37.7 42.1 12.8 9.7 26.6 14.2 16.5 36.8 13.1 20.5 30.9 26.8 (26.2–27.2) 15.6 (14.2–16.6) 16.3 (14.8–17.8) 35.7 (33.3–38.5) 11.9 (10.6–13.1) 18.8 (14.6–20.7) 29.7 (23.5–32.1) 24.3 17.5 14.9 37.3 13.8 17.5 31.3 means data not available. B. castlei sp. nov.

B. bimaculatus sp. nov. B. bleekeri HT Types HT Types NT Vertebrae n=5 n=4 n=6 n=1 Predorsal 8 8 8–9 9 9–10 10 Preanal 28 27–30 27–28 35 35–38 36 Precaudal 37 35–37 34–37 50 48–50 45 Total 109 109–111 107–113 162 130+–162 144+ LL pores Predorsal 7 6–9 5–6 7 7–9 6 Prepectoral 5 4–7 3–4 4 3–4 4 Preanal 28 27–29 25–26 33 33–36 32 Head pores SO 3 3 3 3 3 3 IO 4+1 4+1 4+1 4+1 4+1 4+1 ST 0 0 0 1 1 1 M 6+1 6+1 6+1 6+1 6+1 (5+1) 6+1 POP 3 3 3 3 3 3

Predorsal vertebrae 8–9; preanal vertebrae 27–28; precaudal vertebrae 34–37; total vertebrae 107–113.

Teeth moderately large, conical ( Fig. 3B ). Intermaxillary in about four transverse rows, separated from maxillary and vomerine teeth, mostly excluded from closed mouth. Maxillary and mandibular teeth in bands, wider anteriorly, roughly in four or five rows, narrower posteriorly; in 1 to 2 rows; outermost teeth slightly larger than innermost. Vomerine teeth forming a small oval patch, 3 irregular rows of small teeth followed by several large blunt teeth, roughly in 2 rows.

Coloration. In preservative, brown on dorsum and pale elsewhere. Lateral and ventral surface of body and abdomen without chromatophores; dorsal surface with a darker wash composed of numerous tiny brown chromatophores on either side of dorsal fin. Snout mostly covered by black pigmentation under the skin, extending to level of posterior margin of eye, except for a clearly white band in front of eye; a black patch under skin at about brain chamber; dark pigment outlining supratemporal canal; a large patch of pigment on opercle in front of pectoral-fin base. Row of few black dots on ventral surface of abdomen. Pectoral fin with scattered pigment, denser at base. Dorsal fin uniformly light brownish, without any black marks, each fin ray with clear internal pigment and a black spot at base; anal fin pale, each ray with slight internal pigment and a black spot at base. Caudal fin with a black base and scattered pigment.

Anterior third of stomach blackish, posterior 2/3 pale with some small black patches of pigments internally, pale externally. Intestine mostly damaged but presumably pale with numerous black dots based on the membrane left. Dorsal third of peritoneum densely covered by black or brown pigments; ventral 2/3 of peritoneum unpigmented. Mouth cavity and gill chamber pale.

Distribution. Known from the Philippines at depth 51–333 m ( Karmovskaya & Smith, 2008); newly collected from southwestern Taiwan at depth ca. 200– 300 m.

Remarks. Karmovskaya & Smith (2008) redescribed this species based on 2 additional specimens collected from the Philippines, and no additional information has been provided since then. Our specimens represent the first record in Taiwan.

Several differences were observed in our specimens. Karmovskaya & Smith (2008) reported one single pore on the supratemporal commissure, whereas our specimens have none. In the same work they described B. trimaculatus which also has 10 out of 13 specimens lacking the pore. Our specimens have roughly 3 or 4 transverse rows of teeth on intermaxillary and those on vomer forming a narrow triangular patch, in about 3 irregular rows, whereas Karmovskaya & Smith (2008) reported 2 transverse rows of teeth on intermaxillary and a relatively broad patch of vomerine teeth. These may be attributed to individual variations.

Figures

FIGURE 3. Tooth pattern on upper jaw. A. Bathycongrus bimaculatus sp. nov., NMMB-P7012, paratype. B. B. bleekeri, NMMB-P26214. C. B. castlei sp. nov., NMMB-P21740, paratype. D. B. guttulatus, NMMB-P7607. E. B. graciliceps sp. nov., holotype. F. B. macroporis, NMMB-P29128. Not to scale.

FIGURE 4. Bathycongrus bleekeri Fowler, 1934. A–B, NMMB-P26214, 177 mm TL. C–D, NMMB-P27744, 140.7 mm TL. E. Head pores, NMMB-P25988, 185 mm TL, arrow indicates the ST pore.