Monopterus ichthyophoides

description

Description. For general appearance see Figures 1 and 2. Morphometric data and vertebral counts are presented in Table 1. Body very elongate, eel-like, round to oval in cross section, but laterally compressed in its caudal portion. Depth 27.5 – 35.4 times in TL; body width 1.3 – 1.4 times in its depth. Head prominent, 6.1 – 7.3 times in TL, with bulging adductor muscles behind eye; snout anteriorly rounded in dorsal view. Eye small, covered by thick skin. Posterior naris an oblique slit above, medial to, and slightly in front of eye (Fig. 2 a, b); anterior naris developed as small circular orifice at ventral side of upper lip (Fig. 2 a, c). Lower lip overhung by upper lip, not visible in dorsal view. Lateral-line pores on head not developed. Skin covering branchial chamber smooth, not produced into longitudinal furrows. Gill membrane completely fused to isthmus medially, therefore gill openings reduced to a pair of small slits ventrolaterally on either side of head. Gill filaments absent on all gill arches. Only a single functional (open) gill slit, situated between gill arches three and four, guarded by a fleshy valve originating from ceratobranchial 3; other gill slits closed. No

Monopterus ichthyophoides, a new species of scaled swamp eel (Teleostei: Synbranchiformes: Synbranchidae) from Mizoram, India

diagnosis

Diagnosis. Monopterus ichthyophoides differs from all other species of synbranchids in having only 2 branchiostegal rays (vs 5 – 6). It differs further from all other synbranchids, except M. cuchia, M. fossorius, M. indicus, and M. desilvai by the presence of scales. It differs from the latter four species also by the number of vertebrae (79 – 82 + 34 – 37 = 114 – 117 vs M. cuchia 99 – 112 + 55 – 70 = 166 – 188, M. fossorius 73 + 53 - 56 = 126 – 129, M. indicus 93 – 99 + 42 – 45 = 137 – 144, M. desilvai 75 + 69 = 144). It differs further from M. cuchia in having the scales restricted to the posterior part of its body (vs extending anteriorly up to the head) and from M. desilvai and M. indicus in having scales extending anteriorly far beyond the vent (vs. ending posterior to vent in M. desilvai and M. indicus, but with a small separate scale patch in M. indicus)

Monopterus ichthyophoides, a new species of scaled swamp eel (Teleostei: Synbranchiformes: Synbranchidae) from Mizoram, India

distribution

Distribution. Known only from two localities in the Barak River drainage in Mizoram, India (Fig. 5): Sawleng River, a small stream with muddy bank and bottom (elevation 904 m above sea level) in the vicinity of Sawleng, and a public well (elevation 1006 m above sea level) with a muddy bottom at Luangmual, Aizawl.

Monopterus ichthyophoides, a new species of scaled swamp eel (Teleostei: Synbranchiformes: Synbranchidae) from Mizoram, India

etymology

Etymology. The name ichthyophoides is derived from the Greek ἰχθύς (ichthys), fish, and ὄφɩς (ophis), snake, and the Latin ending – oides, meaning “ similar to ”. It alludes to the striking superficial similarity of this species to large larvae of the caecilian genus Ichthyophis. FIGURE 5. Map of collecting localities of Monopterus ichthyophoides; * PUCMF 3005 holotype and BMNH 2011.5.3.1 paratype, + PUCMF 3006 paratypes.

Monopterus ichthyophoides, a new species of scaled swamp eel (Teleostei: Synbranchiformes: Synbranchidae) from Mizoram, India