Bathycongrus bleekeri Fowler, 1934

Karmovskaya, Emma S. & Smith, David G., 2008, Bathycongrus trimaculatus, a new congrid eel (Teleostei: Anguilliformes) from the southwestern Pacific, with a redescription of Bathycongrus bleekeri Fowler, Zootaxa 1943, pp. 26-36 : 30-33

Bathycongrus bleekeri Fowler, 1934

( Figs. 5–9)

Bathycongrus bleekeri Fowler, 1934: 272

Holotype: USNM 92353 , 76 mm, Philippines, 22 May 1908, station 5257, 7° 22' 12" N, 124° 12' 15" E, depth 51 m, Agassiz trawl, "Albatross."

Other material: USNM 135119 , 1, 180 mm, Philippines, 16 March 1909, station 5403, 11° 10' N, 124° 17' 15" E, depth 333 m; Agassiz trawl, “Albatross.” USNM 135120 , 1, 142 mm, Philippines, same data as USNM 135119.

Diagnosis. Small, moderately elongate; tail slender, but not filiform. Dorsal-fin origin slightly behind origin of pectoral fin. Snout equal to or shorter than eye, projecting beyond lower jaw. Upper labial flange rudimentary or absent. Third supraorbital pore and infraorbital pores enlarged. Teeth small, conical, in narrow bands on jaws; in a slightly elongate patch on vomer, none of the teeth enlarged; intermaxillary teeth partly exposed when mouth closed. Total vertebrae 113, preanal lateral-line pores ca. 25–26.

Description (values given for holotype, with those of other specimens in parentheses; n.a. indicates value not available). Measurements as % TL: preanal length 34 (36–38), predorsal length 17 (21), head length 18 (18), depth at anus 6.6 (6.1–7.3); as % of head length: snout length 22 (19), horizontal eye diameter 22 (24– 28), snout to rictus 37 (28–31), gill opening 13 (16–20), interbranchial 19 (24–25), pectoral-fin length n.a. (27–30). Meristic characters: preanal lateral-line (LL) pores 26 (25), preoperculomandibular (POM) pores 10 (10), infraorbital (IO) pores 5 (5), supraorbital (SO) pores 3 (3), supratemporal commissure (STC) pores 1 (1). Predorsal vertebrae 7 (9), preanal 28 (28–29), precaudal 35 (36–37), total 105 + (113). Pectoral-fin rays 14 (14), dorsal fin-rays 182 + (215–217), preanal dorsal-fin rays 42 (44–49), anal-fin rays 136 + (147–167), caudalfin rays n.a.(5+4, 5+5). Branchiostegal rays 8 (8).

Body moderate, not greatly elongate, compressed, tip of tail slender but not filiform; anus slightly posterior to anterior third of total length. Dorsal fin begins approximately over midpoint of appressed pectoral fin, continuous around tip of tail with caudal and anal fins. Anal fin begins immediately behind anus. Pectoral fin well developed. Gill opening relatively large, upper end at or slightly above midpoint of pectoral-fin base. Myorhabdoi absent, fin rays segmented.

Head deepest about midway between posterior margin of eye and gill opening, tapering anteriorly from that point; snout about equal to or shorter than eye, projecting slightly beyond tip of lower jaw; fleshy part of snout projecting slightly beyond anterior end of intermaxillary tooth patch; rictus nearly below middle of eye. Lower jaw with a downturned flange, upper jaw with flange greatly reduced or absent. Eye large. Anterior nostril tubular, near tip of snout, directed ventrolaterally. Posterior nostril elliptical, with a slightly raised rim, at mid-eye level.

Lateral line complete, ca. 25–26 pores before anus. Head pores large. Supraorbital canal with three pores, the first (ethmoidal) on ventral side of tip of snout, just ahead of lip, the second enlarged and immediately in front of anterior nostril, the third greatly enlarged and immediately above anterior nostril. Infraorbital canal with five pores, four slit-like pores along upper jaw flange, the first three noticeably enlarged, and one large, round pore behind rictus at mid-eye level; adnasal pore absent; no pores behind eye. Preoperculomandibular canal with 10 pores, six before and four behind rictus. Supratemporal commissure with one medial pore.

Teeth ( Fig. 9) moderately large, conical. Intermaxillary teeth in two transverse rows, separated from maxillary and vomerine teeth, mostly excluded from closed mouth. Maxillary and mandibular teeth in bands, wider anteriorly, roughly in four to five rows, narrower posteriorly, in one to two rows; outermost teeth larger than innermost. Vomerine tooth patch longer than broad, reaching about to level of posterior nostril; teeth conical, in approximately four longitudinal rows anteriorly, narrower posteriorly, the middle teeth larger than outer ones and slightly smaller than those of intermaxillary.

Gas bladder terminates behind anus. Stomach reaches about 2/3 of distance from gill opening to anus.

Color in preservative light brown, without markings. Stomach and intestine brown (perhaps black in life). Branchial cavity pale. Holotype retains traces of larval pigmentation as a series of small melanophores just below lateral line, spaced irregularly every several myomeres, from shortly behind pectoral fin to end of tail.

Distribution. Known only from the Philippines.

Remarks. Fowler described Bathycongrus bleekeri from a single juvenile specimen collected during the Albatross Philippine Expedition, 1907–1910. His description was cursory, consisting of a few proportional measurements and some color notes, and he did not provide an illustration. The species has not been reported since and indeed would be difficult to recognize based on Fowler’s account. Two additional specimens were found among the Albatross Philippine material deposited at the National Museum of Natural History, Washington, DC. They were catalogued some years after Fowler’s publication and misidentified initially as Ariosoma brachyrhynchus (= Parabathymyrus brachyrhynchus ) and later as Ariosoma anagoides , both members of a different subfamily. These specimens are substantially larger than the holotype and allow us to provide a redescription of the species here. Although there is some damage to the lower jaw in both specimens, all of the critical characters are still discernable. Most important, both specimens appear to have intact tails, hence their vertebral counts are available.

Castle & Smith (1999: 991) excluded Bathycongrus bleekeri from their reassessment of Bathycongrus , primarily on the basis of three characters. First, the vomerine tooth patch is more elongate and the individual teeth are smaller than those of other Bathycongrus species. Second, the eye is larger and the snout is shorter. Third, the remnants of the larval melanophores, visible on the holotype, are in a single lateral row rather than the three rows characteristic of other Bathycongrus species.

Although B. bleekeri differs in some ways from the other species currently assigned to the genus, these differences are perhaps less significant than Castle & Smith presumed. The vomerine teeth are indeed somewhat different from those of previously known Indo-Pacific species. Rather than a short patch with few teeth, one or two of them distinctly enlarged ( Castle & Smith, 1999: fig. 3), B. bleekeri has an elongate, oval-shaped patch with numerous small teeth. This pattern is similar to that of B. trimaculatus , however (see above), and also to that of the Atlantic B. dubius ( Smith, 1989a: 534) . The eye is larger in proportion to the snout than in other species, but this is a matter of degree rather than kind. The same can be said of the tail, distinctly less filiform than the other species, again a difference in degree. The uniserial lateral larval pigment is found also in Bathycongrus dubius Smith (1989b: 752) . Other characters in common with Bathycongrus include the lack of a well-developed flange on the upper lip, the enlarged infraorbital pores, the elongate gas bladder, and the pigmented stomach. Although the species of Bathycongrus show considerable divergence in a number of characters, they still seem well differentiated from other congrid genera, and we find no compelling reason to separate any of the species, including B. bleekeri , at this time.