Omox biporos Springer 1972

Omox biporos

HOLOTYPE.–CAS 13520, male, 36.9 mm SL, shore of southeast bay of Goh Mak Island, southwest of Trat Bay, east coast of Gulf of Thailand, lat. 11°48′15″ N, 102°29′08″ E; collected by H.A. Fehlmann, et al., 30 October 1957.

PARATYPES.–CAS 13657, 2 specimens, 32.0–35.4 mm SL, and CAS 13656, 37.0 mm SL, cleared and stained, all three with same data as holotype; USNM 205698, 2 specimens, 30.6–45.8 mm SL, Madang Harbor, New Guinea, mangroves behind Nui Island; CAS 13521, 23.4 mm SL, Garayamo Island, Palau Islands.

DESCRIPTION (characters for holotype in parentheses).–Dorsal fin XII, 15–17 (16); anal fin II, 17–19 (19); pectoral fins 13; pelvic fins 1, 2; caudal fin (dorsal procurrent rays-segmented rays-ventral procurrent rays) 5 to 6–13–5 to 6 (6–13–6); vertebrae 10+ 24–26 (25); pleural ribs on vertebrae 3–10; epipleural ribs on vertebrae 1–12 or 13 (13); upper jaw teeth I–20–I to I–25–I (I–22–I); lower jaw teeth I–19–I to I–26–I (I–22–I).

Dorsal fin origin slightly in advance of level of gill opening, notched slightly above last one or two spines; tips of caudal fin rays and posterior dorsal fin rays filamentous in mature males only; lateral line absent on body; midpredorsal supratemporal pore present in only one of seven available specimens. (For other characters see generic diagnosis above.)

PRESERVED COLOR PATTERN.–Males: Pattern variable; in specimens with most-developed pattern, 11 dark, vertical bands present on body separated by broader, paler interspaces; bands darker at mid-level; head with three or four dusky bands separated by paler interspaces; dorsal and anal fins generally dusky; dark spot or two or three dusky stripes present at anterior end of dorsal fin; tips of anal rays pale (swollen in mature males); caudal fin dusky centrally; dark mark basally on pectoral fin separated by pale area from dusky fleshy pectoral fin base; pelvic fins dusky. In males with least-developed pattern the bands of the head and body are fewer in number and appear only as dark spots midlaterally on the body. Females: Similar to males, but dusky bands on body as broad or broader than pale interspaces; bands more distinctly developed than in males; no distinct marks on dorsal, pectoral, and caudal fins.

ETYMOLOGY.–An adjective derived from the Latin bi and the Greek poros, meaning two-holed, in reference to the two sensory pores that appear, one on each side, just anterior to the dorsal fin origin.

Parenchelyurus, new genus

DIAGNOSIS.–No cirri on head; dorsal and anal fins not attached to caudal fin; frontal bones separate in adults; 3–4 circumorbital bones; no kinethmoid; postcleithra normal; ventral hypural plate autogenous; 11–13 dorsal fin spines; 13 (rarely 14) pectoral fin rays; nasal bones separate; 6–8 (usually 7) sensory pores in circumorbital series; 3 sensory pores in mandibular series; 11–12 pores in supra-temporal-preoperulomandibular series; 3 interorbital sensory pores; posterior nostril present, normal; gill opening restricted to area above level of fifth from dorsalmost pectoral fin ray; shortest pelvic fin ray more than half length of longest.

RELATIONSHIP.–Parenchelyurus is most similar to Omobranchus (and vice versa), although one of the two species, P. hepburni, has been repeatedly referred to Enchelyurus, probably because of its overall dark color and small size. The other species, P. hyena, was placed in Graviceps (=Omobranchus) by Whitley (1953). Parenchelyurus differs from Omobranchus primarily in having one external pore at the anterior end of the dentary as opposed to two pores in Omobranchus. The single-pored condition is found also in Enchelyurus and Haptogenys, but these genera exhibit many characters not found in Parenchelyurus. Parenchelyurus has three or four circumorbital bones, and thus differs from all but one species of Omobranchus—O. kranjiensis (Herre), which has four circumorbital bones.

ETYMOLOGY.–Derived from the Greek par meaning near to, and Enchelyurus, a genus of Omobranchini; gender masculine.

TYPE-SPECIES.–Enchelyurus hepburni Snyder, 1908.