Chiloconger philippinensis, Smith, David G. & Karmovskaya, Emma S., 2003

Smith, David G. & Karmovskaya, Emma S., 2003, A new genus and two new species of congrid eels (Teleostei: Anguilliformes: Congridae) from the Indo­West Pacific, with a redescription and osteology of Chiloconger dentatus, Zootaxa 343, pp. 1-19 : 9-13

Chiloconger philippinensis , sp. nov.

( Figs. 7 – 9 )

Chiloconger sp., Smith in Carpenter & Niem, 1999:1682, 1686, fig.6 (in key of the subfamilies and genera, in list of species).

Type material: Holotype, MNHN 1998­0664 (male, 166 mm TL), South China Sea, south­west of Luzon Id.; 28 November 1980, station 59CP4, 14o 00’ N., 120o 16’ E, 190– 186 m depth, beam trawl; C. R. V. “Coriolis”, MUSORSTOM 2. Paratype s, MNHN 2002­ 3730 (4, 161– 183 mm), same data as holotype; paratype MNHN 1998­0666 (female, 190 mm); 29 November 1980, station 63CP4, 14o 07’ N., 120o 15’ E, 230– 215 m depth, beam trawl; C. R. V. “Coriolis”, MUSORSTOM 2.

Diagnosis. A small species of Chiloconger of the subfamily Bathymyrinae , with short bluntly­rounded snout and large brown spot at origin of dorsal fin. Maxillary and mandibular teeth pointed or bluntly conical, close­set in outer series, biserial for the most of length of jaws. Intermaxillary teeth in two transverse rows. Total vertebrae 113–115, preanal lateral­line pores 36–39, predorsal length 18–19 % TL, upper jaw 33–38 % HL.

Description (values given for holotype, with those of paratypes in parentheses). Measurements as % TL: preanal 46.4 (45.3–46.0), predorsal 18.7 (17.6–18.8), head 16.6 (15.5–16.8), trunk 29.8 (28.4–30.5), depth at gill opening 7.5 (6.0–7.5), depth at anus 6.6 (5.9–6.2); as % of head length: snout 18.2 (17.2–20.0), eye 20.0 (20.3–21.7), upper jaw 32.7 (33.3–37.9), gill opening 29.1 (26.5–28.3), postorbital 65.4 (66.7–67.5), interorbital 7.3 (8.3–9.3), interbranchial 25.4 (21.8–26.7), pectoral fin 32.7(35.9–36.7). Meristic characters: preanal LL pores (37) 36–39, POM pores 8, IO pores 3, SO pores 4, STC pores 0, total vertebrae 113 (113, 115), predorsal vertebrae 10 (9, 10), preanal vertebrae 42 (40, 43), precaudal vertebrae 45 (44, 46). Pectoral­fin rays 14 (13, 14), dorsal­fin rays 252 (229, ca. 237), preanal dorsal fin­rays 74 (66, ca. 67), anal­fin rays 147 (157, 167), caudalfin rays 9 (9). Branchiostegal rays 10 (10).

Moderately elongate, head roughly cylindrical, trunk and tail compressed, anus anterior to midlength; tip of tail blunt and stiffened, caudal fin reduced ( Fig. 7 ). Tail 1.1–1.3 times longer than head and trunk. Head deeper than body. Dorsal­fin origin behind gill opening above tip of pectoral fin, over sixth or seventh lateral line pore ( Fig. 8 ). Anal­fin origin at the distance of 180 (169–196) % of head length from gill opening below 39th (37th–40th) pore of lateral line. Dorsal and anal fins confluent with caudal. Pectoral fin well developed. Gill opening large, crescentic, its upper corner slightly below of upper edge of pectoral­fin base. Mouth cleft extending backward almost to level of posterior margin of eye. Snout short, bluntly­rounded, projecting slightly beyond lower jaw, lips with greatly developed upturned labial flanges. Flange of upper lip broad, covering preorbital groove from anterior nostril to a vertical through mid­length of eye; the greatest height of flange almost reaching posterior nostril. Flange of lower lip prominent, longer than flange of upper lip. Fleshy inner lips covering maxillary and mandibular teeth laterally. Eye large, round, covered with dermal membrane, its diameter slightly more than snout length. Anterior nostril tubular, near tip of snout, directed obliquely anterolaterally. Posterior nostril oval in shape, with raised incised rims, placed immediately in front of eye at level of its lower edge. Numerous plicae, with minute filaments, scattered on tip of snout, between nostrils and along branchial region.

Head and lateral line pores relatively conspicuous ( Fig. 8 ). In supraorbital series four pores: one small pore at tip of snout (ethmoidal pore) in front of anterior nostril; one large pore above and slightly before base of anterior nostril; one small papilla­like pore placed above and behind anterior nostril; one small pore before anterior margin of eye over posterior nostril. In infraorbital series three pores: one minute pore (adnasal pore) immediately above base of anterior nostril, one large pore behind anterior nostril, partly hidden in anterior part of labial flange, and one large pore slightly behind mid­eye level, hidden in lip before rictus. No visible infraorbital pore behind rictus. Eight obvious preoperculomandibular pores, six mandibular and two preopercular pores. No pores in supratemporal commissure. Lateral line pores anterior to level of pectoral fin 4 (4), anterior to level of dorsalfin origin 7 (6–7), anterior to level of vent 37 (36–39).

Teeth ( Fig. 9 ) small, sharply or bluntly conical, set in irregular rows, tapering to one row posteriorly in jaws and vomer. Intermaxillary teeth conical, recurved tooth patch in two semicircular rows, separated from maxillary and vomerine teeth. Vomerine teeth conical, shorter and blunter than those of intermaxillary, in a short oblong patch, arranged in irregular four rows anteriorly, tapering to one­two rows posteriorly, ca. 13. Maxillary and mandibular teeth in bands, those of outer row higher than those of inner row, slightly decreasing in size anterior to posterior. Teeth of outer series pointed, straight, densely set. Teeth of inner series blunt and irregularly spaced. Maxillary teeth roughly in three­four rows anteriorly, biserial for the most of length series, uniserial at posterior end of series; posteriormost few teeth directed anteriorly. Mandibular teeth in four­five rows anteriorly, biserial for the most of length series.

Gas bladder attached to vertebrae, extending posterior to stomach, terminating before anus.

Stomach reaching about one­half or two­thirds of way to anus.

Color in preservative yellowish­brown, lighter ventrally; cheeks and lateral sides of body mottled with tiny melanophores; the single irregular midlateral series of melanophores widely spaced slightly beneath skin. Pectoral, anal and caudal fins pale. Dorsal fin with a large brown spot covering first several rays and membrane, dark­edged posteriorly from about middle of trunk to caudal fin. Nostrils and pores whitish. Digestive tract pale, stomach and intestine brownish anteriorly, speckled with scattering melanophores. Branchial cavity pale.

The specimens range from 161 to 190 mm TL. The largest specimen mature female 190 mm TL, egg diameter 0.75–0.95 mm.

Comparison with other species. Chiloconger philippinensis most closely agrees with C. dentatus ( Garman, 1899) in terms of short bluntly rounded snout, large labial flanges, similar arrangement of dentition, head pores and nostril openings, and pattern of coloration of dorsal fin and body. Chiloconger philippinensis differs from C. dentatus by combination of its meristic characters: number of vertebrae (113–115 vs. 118–122), number of preanal lateral line pores (36–39 vs. 19–27), number of supraorbital (4 vs. 3), infraorbital (3 vs. 4) and mandibular pores (6 vs. 4–5). C. philippinensis also shares some morphometric characters with C. dentatus but has relatively shorter head (15.5–16.8% TL vs. 16.8– 20.1%), shorter predorsal length (17.6–18.8% TL vs. 20.1–26.2%) and longer upper jaw (32.7–37.9% HL vs. 22.1–32.5%).

Distribution. Known from two Philippines localities, south­west of Luzon Id. trawled at 186–230 m of depth.

Etymology. The specific name refers to the type locality.

Figures

FIGURE 7. Chiloconger philippinensis, paratype, MNHN 2002 ­ 3730, 183 mm TL.

FIGURE 8. Chiloconger philippinensis, holotype, MNHN 1998 ­ 0664, 166 mm TL, head and anterior body.

FIGURE 9. Chiloconger philippinensis, holotype, upper (left) and lower (right) dentition.