Sicyopterus longifilis de Beaufort, 1912

Maeda, Ken & Saeki, Toshifumi, 2018, Revision of Species in Sicyopterus (Gobiidae: Sicydiinae) Described by de Beaufort (1912), with a First Record of Sicyopterus longifilis from Japan, Species Diversity 23, pp. 253-262 : 255-259

publication ID	https://doi.org/ 10.12782/specdiv.23.253
publication LSID	lsid:zoobank.org:pub:CFC71B89-200A-411A-A8B1-586EADF02E8C
persistent identifier	https://treatment.plazi.org/id/8D206500-9203-B415-FC78-FF2FFDC1FCE7
treatment provided by	Felipe
scientific name	Sicyopterus longifilis de Beaufort, 1912
status

Treatment

Sicyopterus longifilis de Beaufort, 1912 View in CoL

[New Japanese name: Gizagiza-bouzu-haze]

( Figs 1 View Fig , 2A, B View Fig , 3A, B View Fig , 4 View Fig , 5 View Fig , 6A, B View Fig ; Tables 1–4)

Sicyopterus longifilis de Beaufort, 1912: 140 View in CoL (type locality: Seram, Indonesia); de Beaufort 1913: 146; Koumans 1953: 232; Zhou and Gao 2011: 327; Keith et al. 2015b: 110.

Sicyopterus brevis de Beaufort, 1912: 141 View in CoL [type locality: Seram, Indonesia; invalid, precedence given to S. longifilis View in CoL (see Discussion)]; de Beaufort 1913: 147; Koumans 1953: 233; Keith et al. 2015b: 82.

Sicyopterus lacrymosus Herre, 1927: 303 View in CoL (type locality: Luzon , Philippines).

Sicyopterus panayensis Herre, 1927: 313 View in CoL (type locality:

Panay, Philippines). Sicyopterus sp. : Lin 2007: 76. Sicyopterus sp. 1 : Zhou and Gao 2011: 329.

Material examined. Syntypes of Sicyopterus longifilis: ZMA 112562, 2 males (38.0 and 74.7 mm SL; 48.6 and

95.6 mm in total length), upper course of Tubah River, West Seram, Indonesia, 27 February 1910, coll. L. F. de Beaufort [Although de Beaufort (1912) wrote that he described this species from three specimens (49–97 mm in total length), currently only two specimens are available ( Nijssen et al. 1982)]. Syntypes of Sicyopterus brevis: ZMA 110981, 2 females (35.6 and 35.7 mm SL), upper course of Tubah River, West Seram, Indonesia, 27 February 1910, coll. L. F. de Beaufort. Non-type specimens from Okinawa, Japan: URM-P 48275, female (36.6 mm SL), a stream on the eastern slope of Okinawa Island, 18 June 2013, coll. K. Maeda; URM-P 48276, female (57.6 mm SL), a stream on the western slope of Okinawa Island, 28 June 2013, coll. T. Saeki.

Diagnosis. Upper lip without median cleft, but with a lateral cleft on each side of lip; margin of upper lip between lateral clefts minutely serrated. Without tubercle behind median cleft. Ridge beneath the upper lip only with feeble papillae. Premaxillary teeth tricuspid. First dorsal-fin spines, especially second to fifth spines, long and filamentous in males. Posterior tip of first dorsal fin often exceeding base of last soft ray of second dorsal fin in males. Second to fourth spines of first dorsal fin in females somewhat elongate, but the tip of fin not extending to middle of second dorsal-fin base. Membranes notched between spines in female. Second dorsal fin usually with one spine and ten soft rays. Caudal fin with 17–18 (usually 17) segmented rays, including 15–16 branched rays. Pectoral fin with 20–21 rays. Scales in longitudinal series 49–57. Scales on nape and occipital region considerably smaller than scales on lateral sides of body.

Description of syntypes of Sicyopterus longifilis . Two males ( Fig. 1A, B View Fig ; Table 1). Body elongate, cylindrical anteriorly and somewhat compressed posteriorly. Snout round and protruding beyond upper lip. Anterior naris short and tubular, posterior naris not tubular. Mouth inferior with upper jaw projecting beyond lower jaw. Upper lip without median cleft, but with a lateral cleft slightly posterior to the middle of each side of the lip. Margin of upper lip minutely serrated between lateral clefts. Premaxillary teeth fine and tricuspid. Dentary with six or eight canine-like symphyseal teeth and a row of horizontal teeth enclosed in a thick, fleshy sheath. First dorsal fin with six spines; spines elongate and filamentous (third spine longest) and posteriormost point of first dorsal fin (tip of third spine) extending to the base of the eighth soft ray of the second dorsal fin in the smaller specimen (38.0 mm SL) and exceeding the base of the last soft ray of the second dorsal fin in the larger one (74.7 mm SL). Second dorsal fin with one spine and ten soft rays; fifth or sixth soft ray longest. Anal fin with one spine and ten soft rays; ninth soft ray longest. Caudal fin round- ed, with 17 segmented rays, including 15 branched rays. Pectoral fin with 20 rays. Pelvic fins joined to form a strong cup-like disk with fleshy frenum. Occipital region (posterior three-fourths) and body scaled, but pectoral-fin bases naked. Ctenoid scales covering lateral and dorsal sides of body. Scales on nape and occipital region cycloid and considerably smaller than scales on lateral sides of body. Belly covered with cycloid scales. Anteriormost several scales on side of body (behind pectoral-fin base) cycloid. Cycloid scales also occurring on first and second dorsal-fin bases, anal-fin base, caudal-fin base, and proximal part of caudal fin. Scales in longitudinal series 55 or 57; scales in transverse series 18; circumpeduncular scales 28; predorsal scales 15 or 19. Urogenital papilla rounded. A drawing of S. longifilis (probably one of the syntypes) was provided by de Beaufort (1913). Although pigmentation is somewhat indistinct due to over a century of preservation, major markings are visible in the syntypes: two brown Y-shaped bars laterally on body below second dorsal-fin base, followed by two brown oblique bars laterally on caudal peduncle. Dusky brown triangular bar below eye. One indistinct brown blotch on middle of membrane between third and fourth spines of first dorsal fin. Dusky brown triangular marking on middle of pectoral fin. Proximal part of pelvic fin brown in smaller specimen. No distinct markings on second dorsal, anal, and caudal fins.

Description of syntypes of Sicyopterus brevis . Two females ( Fig. 1C, D View Fig ; Table 1). Morphologies corresponding to syntypes of S. longifilis , but having fewer dentary symphyseal teeth (3 vs. 6 or 8 in S. longifilis ), shorter spines on first dorsal fin (posteriormost point of first dorsal fin extending to base of spine or second soft ray of second dorsal fin vs. extending to or exceeding posterior part of second dorsal fin), second spine longest in first dorsal fin (vs. third spine), anterior rays longer in second dorsal and anal fins (vs. middle or posterior rays longest), smaller first and second dorsal, anal, caudal, and pectoral fins (vs. larger fins), rounded square urogenital papilla with slightly concave posterior margin (vs. rounded), and no distinct markings on body and fins (vs. some markings visible).

Description of non-type specimens from Okinawa. Two females ( Fig. 2A, B View Fig , 3A, B View Fig , 4 View Fig , 5 View Fig , 6A, B View Fig ; Table 1). Morphologies correspond to syntypes of S. brevis . Some additional characters which were not examined in the type series of S. longifilis and S. brevis are described below. Second to fourth spines of first dorsal fin elongate (second spine longest) and membranes deeply notched between second and third, third and fourth, and fourth and fifth spines. Cephalic sensory pore system A′, B, C, D(S), F, H, L′, M′, N, and O′ ( Fig. 4 View Fig ). Oculoscapular canal not interrupted. Preopercular canal with three pores (M′, N, and O′). Cutaneous sensory papillae developed over dorsal, lateral, and ventral surface of head ( Fig. 4 View Fig ).

In preservative, dorsal and lateral background yellowish brown, ventral side cream. Triangular black marking extending from ventral margin of eye to posterior end of mouth. Two dusky brown Y-shape bars laterally on body below second-dorsal-fin base, followed by two oblique bars laterally on caudal peduncle. First dorsal fin translucent with gray mottling on posterior part. Second dorsal fin translucent with gray mottling on proximal three fourths and with a pale gray line on distal margin. Anal fin translucent with a submarginal gray line. Caudal fin translucent with subdorsal and subventral pale gray lines; pale gray spots on proximal two thirds of middle rays. Pectoral fin gray, but dorsal and ventral parts translucent in larger specimen; pectoral fin translucent and only proximal part gray in the smaller specimen. Pelvic fin translucent.

Color in life variable ( Figs 5 View Fig , 6A, B View Fig and field observations). Dorsal and lateral background brown, ventral side whitish. Seven dusky brown blotches on dorsal side from posterior part of occipital region to caudal peduncle, anterior blotches somewhat indefinite, third to fifth ones subdivided. Dorsal and lateral side of head mottled with small dusky brown markings. Dusky brown longitudinal stripe extending from tip of snout to below eye and to dorsal part of pectoral fin base, stripe continuing along lateral midline of body. Four dusky brown blotches along lateral midline of posterior part of body. Triangular black marking below eye sometimes highlighted. Markings of head and body often became indistinct ( Fig. 5C View Fig ). Dorsal, anal, and caudal fins translucent to yellowish or orange; markings similar to those of preserved specimens. Distal parts of second to fifth spines of first dorsal fin pale orange to bluish white. Anal fin with bluish-white edge. Narrow bluish-white lines dorsally along subdorsal gray line and ventrally along subventral gray line of caudal fin. Dorsal and ventral parts of pectoral fin with orange tint; gray and cream dots on proximal part. Pelvic fin translucent.

Occurrences and habitats in Okinawa. This taxon is very rare. In addition to the two individuals collected in 2013 (described above), one individual was observed in July, 2014 (not collected). These three specimens were found in different streams, although detailed localities are not shown here due to the conservation perspective. Two of them are on the eastern slope and the other is on the western slope of the island. These three sites are located from 0.4–1.3 km from the upper limit of the estuary, respectively, and all sites are lower than 10 m a.s.l. They were observed with two congeners, Sicyopterus lagocephalus and Sicyopterus japonicus , some other amphidromous gobioids, including Stiphodon percnopterygionus Watson and Chen, 1998 , Awaous melanocephalus (Bleeker, 1849) , and Rhinogobius nagoyae Jordan and Seale, 1906, and the diadromous Kuhlia marginata (Cuvier in Cuvier and Valenciennes, 1829).