Donna M. GUARTE * and Wilfredo L. CAMPOS
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ACTA ICHTHYOLOGICA ET PISCATORIA (2016) 46 (4): 361–366 DOI: 10.3750/AIP2016.46.4.09 FIRST RECORD OF EVOXYMETOPON TAENIATUS (ACTINOPTERYGII: PERCIFORMES: TRICHIURIDAE) FROM THE PHILIPPINES Donna M. GUARTE* and Wilfredo L. CAMPOS OceanBio Laboratory, College of Arts and Sciences, University of the Philippines Visayas, Miagao, Iloilo, 5023 Philippines Guarte D.M., Campos W.L. 2016. First record of Evoxymetopon taeniatus (Actinopterygii: Perciformes: Trichiuridae) from the Philippines. Acta Ichthyol. Piscat. 46 (4): 361–366. Abstract. The channel scabbardfi sh, Evoxymetopon taeniatus Gill, 1863 has not been known from the Philippine waters. Our presently reported fi nding of two specimens (114.5 and 133.1 cm SL) of this species from the Philippines extends the range of this species to the central Indo-Pacifi c. The specimens captured were both male, one with developing gonads, and the other one—mature. We examined and described the fi sh found, providing morphometric and meristic analyses. The species can be distinguished from its congeners by having a convex upper head profi le, steep sagittal crest slope, 82 dorsal fi n rays with a defi ned notched at the tenth ray, a black dorsal fi n membrane before the notch, and 15 externally visible anal fi n rays that are bound with a membrane. The analyses included also relations with size of the four known Evoxymetopon species. Only one signifi cant relation was revealed by the regression analyses—between SL and % pre-anal length. We provided also an updated identifi cation key for the genus. Keywords: new record, range extension, morphological description, morphometric trends, scabbardfi sh The trichiurids, commonly known as cutlassfi shes, This paper reports the fi rst records of the channel hairtails, or scabbardfi shes, are widely distributed in scabbardfi sh, Evoxymetopon taeniatus Gill, 1863, in the tropical to warm temperate waters. They typically live Philippine waters. Two specimens of E. taeniatus were close to the bottom on the continental shelf and the recorded from catches of modifi ed hook and line fi shing upper slope, reaching the depths of 50–1500 m (rarely on two different occasions off the coast of Naba, Culasi 2000 m), with many species exhibiting diel vertical in Antique, in western Panay Island central Philippines migrations (Nakamura and Parin 1993). At present, (Fig. 1) from 20 April to 10 May 2016. There are to there are 47 valid species of trichiurids (Eschmeyer date 53 recorded occurrences of this species worldwide and Fong 2016), belonging to 11 genera (Eschmeyer et (Anonymous 2016b), but only a few references on their al. 2016). Of these, 9 species have been reported from biology are available. The species is reportedly more the Philippine waters. “Trichiurus japonicus Temminck widespread in the west Atlantic (Froese and Pauly 2016). et Schlegel, 1844” was not among them. While the In the west Pacifi c, reports on its occurrence are limited to latter was earlier reported by Herre (1953) as a separate Japan, Taiwan, and Korea. species, it is now considered a junior synonym of the Two specimens of Evoxymetopon taeniatus were wide-spread species Trichiurus lepturus Linnaeus, identifi ed in this study. The fi rst specimen measured 1758 (Carpenter and Niem 2001, Froese and Pauly 114.5 cm SL, while the second one—133.1 cm SL. Both 2016). Chakraborty et al. (2006), however, believe specimens were caught using handlines modifi ed to that T. japonicus is a valid species, as inferred from its catch trichiurids (by means of baited hooks tied to and DNA analysis. suspended from the ends of a 1.2 m iron rod attached in Trichiurids make up a large fi shery worldwide, the middle to a cylindrical lead weight at the end of the with total landings amounting to 1.26 million t in 2014 main fi shing line). Identifi cation of the species followed (Anonymous 2016c), most of which were caught in the Gill (1863), Nakamura and Parin (1993), Sakiyama et al. north-west Pacifi c. In the Philippines, annual hairtail (2011), Fricke et al. (2014), and Hata et al. (2015). landings from 2002–2014 approximated 15 000 t per Standard morphometric measurements were taken year (Anonymous 2016a) which is only 0.7% of the total following Hata et al. (2015), whereby length measurements marine-fi sheries landings in the country. are expressed as percentages (%) of the specimen’s standard * Correspondence: Donna M. Guarte, OceanBio Laboratory, College of Arts and Sciences, University of the Philippines Visayas, Miagao, Iloilo 5023 Philippines, phone: +63 33-315-9271, fax: +63 33-315-9271, e-mail: (DMG) [email protected], (WLC) [email protected]. 362 Guarte and Campos 20°N developing stage, while the larger one (133.1 cm SL)—in mature stage. Detailed descriptions of the specimens are presented below. 18° N Short description of the Philippine specimens. Meristics and morphometrics are given in Table 1. Body elongate, 16° N slender, deep and highly compressed with triangular pectoral fi n, reduced scale-like pelvic fi n (Fig. 2D), and small forked caudal fi n (Fig. 2E). Body silvery white, with 14° N slight reddish brown cast dorsally and several longitudinal yellow stripes on body. Head oblong with steep sagittal crest (Fig. 2C). Dorsal fi n elements of sub-equal length: 12° N 82, with defi ned notch at 10th element (Fig. 2A–C). Colour of dorsal fi n membrane before notch black and 10° N transparent thereafter (Fig. 2A–C). Externally visible anal fi n rays: 15. Comparison with other species. The channel 8N° scabbardfi sh, Evoxymetopon taeniatus, is externally similar to Evoxymetopon moricheni Fricke, Golani et Appelbaum- Golani, 2014, which also has a steep slope in the anterior 6N° 222 km part of the head, a crescent-shaped nostril, and no fi lament on the fi rst dorsal fi n spine. They however differ in the 116°°°°° E 118 E 120 E 122 E 124 E 126° E following features: E. taeniatus has 15 externally visible anal fi n soft rays, versus 17 in E. moricheni; 19 lower gill Fig. 1. Map of the Philippines showing the location of the rakers (vs. 13 in E. moricheni); silvery white body with sampling site, Culasi, Antique in Panay Island (black longitudinal stripes (vs. plain silvery body without stripes); circle) anterior head portion without blackish margin (vs. blackish margin on head continuing along the anterior half of the length (SL). Some modifi cations in fi n counts were made, dorsal fi n base); 1st to 9th dorsal fi n elements with blackish such as instead of listing down the number of total external membrane (vs. 1st to 5th elements only); and dorsal fi n fi n rays (spinescent + external easily distinguishable rays), notched at the 10th element (vs. 8th through 9th element the count includes only the visible and distinguishable notch) (Fricke et al. 2014). Evoxymetopon taeniatus is external fi n rays (Fricke et al. 2014). Hence, external further distinguished from the other species of the genus anal fi n ray counts are presented as x + 15, where x is by its lack of a fi lament in the 1st dorsal fi n spine. The the number of spinescent anal rays. This modifi cation was fi lament is sword-like in Evoxymetopon macrophthalmus done because precise counting of the spinescent rays is Chakraborty, Yoshino et Iwatsuki, 2006 and elongate in diffi cult due to their very minute size, and are thus prone Evoxymetopon poeyi Günther, 1887. It has crescent-shaped to miscounting. Another modifi cation was the addition of nostrils (Nakamura and Parin 1993), although the shape is the number of notched dorsal fi n elements and the number not clear in our specimens, and 82 (range 81–82) dorsal of dorsal fi n elements with a blackish membrane. These fi n elements, while E. macrophthalmus and E. poeyi have characteristics were added to help in distinguishing this slit-like nostrils and 90 and 91–93 dorsal fi n elements, species from other closely-related species in the family, respectively. Evoxymetopon taeniatus further differs where references are relatively scarce. Aside from the from E. macrophthalmus by not having a blackish margin above, sex and maturation stages of the specimens were on the head, and from E. poeyi by having 15 externally also noted. visible anal fi n rays (vs. 20) (Fricke et al. 2014). Measurements and counts of Evoxymetopon taeniatus Morphometric trends. Fin counts and %SL measurements and of other Evoxymetopon species from different authors of Evoxymetopon from Sakiyama et al. (2011) and Hata et (Gill 1863, Nakamura and Parin 1993, Fricke et al. 2014, al. (2015) were included in the analysis for morphometric Hata et al. 2015, Sakiyama et al. 2011) were compiled and trends (Table 1). Thus, 6 specimens were analysed for used in this study to examine relations with size and to possible relations between SL and the other morphometric update the identifi cation key of the genus. For Sakiyama et measurements. The regression analyses showed only one al. (2011), length measurements were converted to %SL to signifi cant relation (Fig. 3), between SL and % pre-anal standardize the format and for easier comparison. Simple length (r2 = 0.909, P = 0.003). The number of dorsal fi n linear regression was employed to quantify the relations. elements, as well as lower gill raker counts also tend to increase with size, but these covered very narrow ranges Family Trichiuridae Rafi nesque, 1810 (Table 1) and were not signifi cant. Genus Evoxymetopon Gill, 1863 Identifi cation key for Evoxymetopon species. Based Evoxymetopon taeniatus Gill, 1863 on information reported in the literature and on the The specimens in this study were both males, with the data recorded