Lamnostoma mindora (Jordan & Richardson, 1908)

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 mindora ( Jordan & Richardson, 1908)

تwmẘü

Common name: Mindora Snake Eel

Figures 1A–1C , 2A–2B , 7A ; Table 1

Caecula mindora Jordan & Richardson, 1908: 239 (holotype: CAS-SU 20209; type locality: Mindoro Island, Philippines); Herre, 1923: 183.

Sphagebranchus mindora ( Jordan & Richardson, 1908): Weber & de Beaufort, 1916: 322.

Lamnostoma mindora ( Jordan & Richardson, 1908): McCosker, 1977: 69; Séret & Dingerkus, 1992: 169; Chen & Fang, 2002: 75; Chiu, 2014: 15; McCosker, 2014: 339; Ho et al., 2015: 168; Miesen et al., 2016: 81.

Lamnostoma midorum ( Jordan & Richardson, 1908): Hatooka & Yoshino, 1998: 25; Chang & Tsai, 2003: 77; Chang & Tsai, 2004: 51, 52, 54, 55.

Specimens examined. TOU-AE 7087 (287 mm TL), sex unknown, Xiu-gu-luan River, eastern of Taiwan, 2008; ASIZP 62051 (251–272 mm TL), 2 specimens, sex unknown, Hua-lien River , Hua-lien county, eastern of Taiwan, 5 Oct. 1999, coll. J.- L. Huang ; ASIZP 75026 (182–428 mm TL), 5 specimens, sex unknown, Yi-lang county , northeastern of Taiwan, 10 Jan. 2008, coll. H.- C Ho ; ASIZP 80724 (312 mm TL), sex unknown, Mei-lun River , eastern of Taiwan, 1 Jul. 2009, coll. S.- P. Huang ; ASIZP 80725 (266 mm TL), sex unknown, Mei-lun River , eastern of Taiwan, 1 Jul. 2009, coll. S.- P. Huang ; ASIZP 80726 (319 mm TL), sex unknown, Lin-bien River , southwestern of Taiwan, 14 Dec. 2005, coll. S.- P. Huang.

Diagnosis. Eye situated about 1/3 length of upper jaw from snout tip; 2 preopercular pores; gill opening lateral, without anterior duplicate gill membrane; distance between dorsal-fin origin and upper margin of gill opening 10.5–26.5% HL; no papilla on both of nostrils; 2 rows of white spots on lateral side of head meeting above gill opening and becoming single row posteriorly, and forming a “Y”.

Description. Head moderately slender, slightly flat dorsally after the eyes; snout relatively blunt at tip; eye placed near 1/3 of upper jaw length from the tip of snout; no papilla on both of nostrils; gill opening lateral without anterior duplicate gill membrane.

Body moderately elongated; tail longer than head and trunk, vent situated before the midpoint of total length; HL 11.3–12.8% TL, TR 33.0–36.3% TL, Tail 51.9–56.1% TL; distance between dorsal fin origin and gill opening about 17.7–26.5% HL.

Teeth on jaws uniserial and conical, comprising intermaxillary 5, maxillary 37–46 on each side, vomerine 7–9, dentary 32–35 on each side.

Cephalic pores: SO 1 + 3, IO 4 + 2, POM 4 + 2, ST 3, F 1. Lateral-line pores: PGLL 10, PDLL 13–15, PALL 57–66, TLL 128–135.

MVF: 14-59.1-146.7 (n = 11). PDV 13–16, PAV 54–61, TV 141–150.

Coloration in 75% EtOH dark dorsally, yellowish to brownish on belly, all fins pale; all sensoring pores black. Two rows of white spots on lateral side of head meeting above gill opening and becoming single row posteriorly, forming a “Y” ( Figure 7A ).

Distribution. Philippines (type locality), Java, Indonesia ( Kottelat, 2013), eastern Taiwan ( Hatooka & Yoshino, 1998) and southwestern Taiwan ( Chang & Tsai, 2003, 2004).

Remarks. This species has the longest tail relative to total length among species of the genus Lamnostoma . Both nostrils lacking a flap, the posterior nostril is placed between the 2nd and 3rd IO pore and has the appearance of an inverted triangle in lateral view; its snout is moderately elongate. The morphological characters described above generally agree with the description in Hatooka & Yoshino (1998) and Chang & Tsai (2003) ( Table 1). The first Taiwanese record of Lamnostoma mindora was mentioned in Hatooka & Yoshino (1998) and based on a specimen collected from the Xiu-gu-luan River in eastern Taiwan. Subsequently, this species was also found in southwestern Taiwan ( Chang & Tsai, 2003, 2004), all specimens having been collected from downstream parts of rivers.

McCosker (personal communication) suggested that Lamnostoma kampeni may be a junior synonym of L. mindora based on its morphometric composition, which is within the range of individual variation. The holotype specimen of another nominal species, L. taylori was destroyed during WWII. Hatooka & Yoshino (1998) considered L. taylori to be a junior synonym of L. mindora based on the key presented in Herre (1923), which differ slightly in body depth (25–30 times in TL in L. mindora vs. about 18 times in L. taylori ).

Figures

FIGURE 1. Lamnostoma mindora (Jordan and Richardson, 1908), TOU-AE 7087, 287 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 2. Lamnostoma mindora (Jordan and Richardson, 1908), TOU-AE 7087, 287 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.