Muraenichthys longirostris Hibino & Ho & Mccosker 2019, sp. nov.
Creators: name: Hibino, Yusuke
name: Ho, Hsuan-Ching
name: Mccosker, John E.
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Actinopterygii
Anguilliformes
Ophichthidae
Muraenichthys
Muraenichthys longirostris

description: Muraenichthys longirostris sp. nov.
(Slender-snout worm eel) (Þḓƃǿ)
Holotype. NMMB-P 24388, 206 mm TL, off Dong-gang, Pingtung, southwestern Taiwan, 24 August 2016, bottom trawl, collected by H.-C. Ho from a fish landing ground.
Diagnosis. A species of Muraenichthys having a slender snout, its length 18% HL, with the following combination of characters: head 11% TL, tail 67% TL; dorsal-fin origin anterior to a vertical through mid-anus, horizontal distance from the vertical to the origin 113% HL; teeth relatively slender, uniserial on maxilla and vomer; predorsal vertebrae 23, preanal 41 and total 131.
Description. Counts and measurements (in mm) of the holotype: predorsal vertebrae 23; preanal vertebrae 41; total vertebrae 131; preanal lateral-line pores 42. Total length 206; head length 23.3; trunk length 45.5; tail length 137.3; predorsal length 40.9; body depth at gill opening 6.6; body depth at mid-anus 6.7; body width at gill opening 5.8; body width at mid-anus 5.9; dorsal-fin origin to anus 26.1; upper-jaw length 10.3; length of mouth gape 9.4; snout length 4.2; snout tip to tip of lower jaw 1.3; eye diameter 1.9; interorbital width 2.3; gill-opening length 1.6. Body long, subcylindrical, its depth at gill opening 31.2 in TL (Fig. 1); tail compressed posteriorly, its depth weakly reduced gradually.
Head moderately large, branchial basket slightly expanded; head 8.8, and head and trunk 3.0 in TL; snout relatively long and slender, tip relatively acute, its length more than twice eye diameter; ventral groove on snout absent; lower jaw included in upper jaw, its tip beyond anterior base of anterior-nostril tube; mouth large, rictus well behind a vertical from posterior margin of eye and slightly behind a vertical through last infraorbital pore, along with a groove reaching to end of jaw; eye moderate in size, 5.4 in upper jaw and 12.3 in HL, covered by a transparent skin; mid-eye located above mid-jaw (mid-point between tip of snout and end of maxilla); anterior nostril a simple ventrally projected tube, its length half of eye diameter, its opening with a very low rim; inner opening of posterior nostril above upper lip, and outer opening oblique and outside the mouth; rim of outer opening projected ventrally; lips mostly smooth with scattered papillae on upper lip; interorbital region smooth, slightly convex; gill opening constricted, located ventrolaterally.
Dorsal and anal fins low, slightly elevated in posterior region of tail, ending confluent with caudal fin; dorsal fin originating at about 2/5 of trunk; caudal fin prominent and tip rounded; pectoral fin absent.
Head pores small but obvious; arrangement of sensory pores on head as follows (Fig. 2A): one + four on supraorbital; three + two on infraorbital, one between anterior and posterior nostrils; six on mandible and three on preopercle; midtemporal and interorbital pores present.
Lateral-line developed, sensory canal reaching middle portion of tail, 11 in branchial basket, 23 anterior to dorsal-fin origin, 42 anterior to anus, and 80 in total.
Teeth (Fig. 2B, C) moderate in size, conical, pointed, relatively slender; teeth on maxilla and vomer uniserial; teeth on mandible mostly uniserial with an additional tooth at each inner side around the symphysis; seven plus three intermaxillary teeth form an oval cluster, the anterior margin arranged in a circular pattern.
Color (Fig. 1) (preserved in 50% isopropyl alcohol) of head and body brown, lower half of head to anterior tail region relatively paler. Dorsal and anal fins pale whitish brown, becoming darker before tail tip; caudal fin dark brown.
Distribution. Known only from the holotype, from off southwestern Taiwan.
Etymology. From the Latin, longirostris, in reference to the snout shape.
Remarks. The new species can be easily distinguished from all congeners by its slender and long snout (18% HL vs. 8.4–15.5% HL). The snout shape is similar to that of members of the genus Scolecenchelys Ogilby, 1897. The position of the dorsal-fin origin overlaps with that of M. thompsoni. The former can be separated from the latter by the snout shape and length (vs. 9.5–14% HL) and its longer tail (67% TL vs. 57–64% TL).
Hibino & Kimura (2015) defined the eye of the congeners of Muraenichthys as located anterior to mid-jaw, but the position of the eye of the present species is just mid-jaw (mid-point between tip of the snout and end of maxilla). Except for these, our new species agrees well with all other diagnostic characters of Muraenichthys. In addition, the location of the orbit (from x-ray photo) corresponds with that of other Muraenichthys. Therefore, we recognized the new species as a species of Muraenichthys, and the character of the eye location is expanded from “eyes located anterior to mid-jaw” to “mid-eye located anterior to or just above mid-jaw” for the genus.
description: Published as part of Hibino, Yusuke, Ho, Hsuan-Ching & Mccosker, John E., 2019, A new species of Muraenichthys (Anguilliformes: Ophichthidae) from Taiwan with redescription of Muraenichthys thompsoni Jordan & Richardson, 1908, pp. 41-48 in Zootaxa 4702 (1) on pages 42-44, DOI: 10.11646/zootaxa.4702.1.9, http://zenodo.org/record/3562867