Lamnostoma polyophthalmum ( Bleeker, 1853 )

Chiu, Yung-Chieh, Shao, Kwang-Tsao, Huang, Shih-Pin & Chen, Hong-Ming, 2018, The freshwater snake eel genus Lamnostoma (Anguilliformes: Ophichthidae) in Taiwan, with description of a new species, Zootaxa 4454 (1) : -

Lamnostoma polyophthalmum ( Bleeker, 1853)

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Common name: Ocellated Snake Eel

Figures 3A–3C , 4A–4B , 7B ; Table 1

Dalophis polyophthalmus Bleeker, 1853: 299 (holotype: BMNH 1867.11.28.310; type locality: Priaman , Indonesia; poor condition).

Anguisurus punctulatus Kaup, 1856a: 24 ; Kaup, 1856b: 50 (syntype whereabouts unknown; type locality: Java, Indonesia).

Sphagebranchus polyophthalmus ( Bleeker, 1853) : Weber & de Beaufort, 1916: 320.

Lamnostoma orientalis ( McClelland, 1844) : McCosker & Castle, 1986: 179 (not of McClelland).

Lamnostoma polyophthalmum ( Bleeker, 1853) : Hatooka & Yoshino, 1998: 22; Chang & Tsai, 2003: 76; Kottelat, 2013: 44; Hatooka, 2013: 269.

Lamnostoma polyophthalma ( Bleeker, 1853) : Fricke et al., 2014: 22.

Specimens examined. TOU-AE 7226 (209 mm TL), sex unknown, downstream of Long-long River , Gong-liao, New Taipei city, catch net, coll. J.- C. Dai . TOU-AE 7235 (304 mm TL), sex unknown, collected together with TOU-AE 7226. Other locality. ASIZP 0 0 62047 (415 mm TL), sex unknown, Ryukyu Islands , Okinawa prefecture, Japan, 1 May 2000, unknown collector.

Diagnosis. Gill opening ventral; ventral width between gill opening 6.5–6.9% HL; two POP; 33–41 teeth on lower jaw; lateral white spots on head without hill-shaped papilla, very faint ventrally.

Description. Head moderately slender cylindrical and uncompressed; snout sharp, pointed, not elongate; posterior margin of anterior nostril and the anterior edge of posterior nostril with a slim labial papilla obvious in lateral view, posterior a hole situated at the interspace between the 1 st and 2nd IO pore; gill opening ventral.

Body moderately elongated, tail shorter than head and trunk, vent placed behind midpoint of total length. HL 9.9–10.1% TL, TR 40.2–43.4% TL, Tail 45.3–49.8% TL; distance between dorsal fin origin and gill opening about 23.3–33.3% HL, ventral width between gill opening 6.5–6.9% HL.

Teeth on both jaws uniserial and conical, comprising intermaxillary 5, maxillary 36–41 on each of side, vomerine 12–15, dentary 33–41 on each of side.

Cephalic pores: SO 1 + 3, IO 4 + 2, POM 4 + 2, ST 3, F 1. Lateral-line pores: PGLL 8, PDLL 15, PALL 65–66, TLL 127–129.

MVF: 12.5-63-136.5. This species has the highest number of preanal vertebrae among species of the genus Lamnostoma .

Coloration: Body dark dorsally, whitish to yellowish ventrally; patterns of white spots on lateral of head arranged in arch, 2 rows of spots not meeting, lower row very faint ventrally ( Figure 7B ), numerous white spots on head, each corresponding with a sensory pore, and extending posteriorly along lateral-line with another not associated with a pore spot above it for 4–5 lateral-line pores, not continuous past vent.

All the morphological characters of specimens examined generally agree with the description in Hatooka & Yoshino (1998) and Chang & Tsai (2003) except for larger eyes ( Table 1).

Distribution. This species is known from Indonesia ( Bleeker, 1853; Kaup, 1856b), Luzon in the Philippines ( Herre, 1953), Japan ( Hatooka & Yoshino, 1998) and northern Taiwan.

Remarks. Although the holotype of this species is damaged, a careful examination was performed by Dr. Hibino and his morphological data provided herein. Additional morphological data obtained from other non-type specimens by Dr. McCosker (personal communication) and as reported by Hatooka & Yoshino (1998) are also presented. Based on this information Lamnostoma polyophthalmum is very similar to L. orientalis ( McClelland, 1844) , but a type specimen and more adequate description of the later are still required. Hatooka & Yoshino (1998) indicated the distance between the dorsal fin origin and gill opening (DGW in this study) is the only difference to distinguish these two species, and they pointed out the L. orientalis in McCosker & Castle (1986) is the same species with L. polyophthalmum . The two specimens listed above provide the first record from the species from Taiwan.

Figures

FIGURE 3. Lamnostoma polyophthalmum (Bleeker, 1853), TOU-AE 7226, 209 mm TL. A. Lateral view of the whole body. B. Left view of head. C. Top view of head. Bar = 10 mm. Abbreviation: DFO, dorsal fin origin.

FIGURE 4. Lamnostoma polyophthalmum (Bleeker, 1853), TOU-AE 7226, 209 mm TL. A. Lateral view of head showing the arrangement of cephalic pores. B. Illustration of dentition. Abbreviation: F, frontal pore; ST, supratemporal pores.

FIGURE 7. Lateral view of head of three Lamnostoma species in this study. A. L. mindora. White spots forming a “Y”; B. L. polyophthalmum. Spots arranged in an arch, the two rows of spots not meeting posteriorly the lower very faint ventrally. C. L. taiwanense sp. nov. Lower spots on a series of hill-shaped papillae, all spots clearly defined.