Centrogenys vaigiensis ( Quoy & Gaimard, 1824 )

Matsunuma, Mizuki, Kai, Yoshiaki & Motomura, Hiroyuki, 2017, Syngnathus chihiroe, a new species of pipefish (Syngnathidae) from southern Japan, Cybium 41 (3), pp. 290-292 : 290-292

Centrogenys vaigiensis ( Quoy & Gaimard, 1824)

( Figs 1 , 2 , 3 )

Material examined

FAKU 103752 , 73.7 mm SL, Port Louise , Mauritius, 5 th Japanese Antarctic Research Expedition , RV Soya , 31 Mar. 1961 .

Comparative material

Centrogenys vaigiensis (5 specimens): KAUM-I. 8985, 102.1 mm SL, channel between Irabu-jima and Shimoji-jima islands , Miyako Islands, Ryukyu Islands, Japan ; KAUM-I. 52077, 44.5 mm SL, KAUM-I. 52078, 53.0 mm SL, KAUM-I. 52347, 75.2 mm SL, KAUM-I. 59368, 54.4 mm SL, Merambong Shoal, Johor Strait, Johor, Malaysia .

(1) Laboratory of Marine Biology, Faculty of Science, Kochi University, 2-5-1 Akebono, Kochi 780-8520, Japan.

(2) Maizuru Fisheries Research Station, Field Science Education and Research Center, Kyoto University, Nagahama, Maizuru,

Kyoto 625-0086, Japan. [[e-mail]]

(3) The Kagoshima University Museum, 1-21-30 Korimoto, Kagoshima 890-0065, Japan. [[e-mail]]

Description clearly larger than anterior nostril. Maxilla expanded posteriorly

Morphometrics and meristics are given in table I. Body robust, with distinct ridge on dorsal edge, its posterior margin extending slightly elongate ( Fig. 1 ). Head large; snout very short, robust, with beyond vertical through mid-orbit. Both jaws with bands of coni-

rounded contour in lateral view, its length 19.3% of head length. cal villiform teeth; vomer with V-shaped patch of conical villiform

Eye large with narrow fleshy rim; interorbital space broad with lat- teeth; palatine with elongate band of conical villiform teeth, its erally expanded fleshy rim, bony interorbital width 50.7% of soft maximum width about half that of teeth bands on jaws. Upper gill interorbital width. Anterior nostril close to posterior nostril, with a rakers on lower limb relatively broad and elongate, longest raker low rim and elongate fringed skin flap with pointed tip (its length length about half that of longest gill filament, other rakers comb-

26.1% of orbit diameter) on posterior margin; posterior nostril oval, like. Preopercle margins spinous, serrated; ventral margin with three strong spines ( Fig. 2 ); posterior margin strongly

Table I. – Morphometric measurements, expressed to percentages of standard length, and serrated [29 (partially broken) and 26 serrae on left

meristic counts of Centrogenys vaigiensis . and right sides, respectively]. Margins of subopercle and interopercle smooth. Opercle with long flattened

Mauritius specimen Comparative specimens

spine centrally, its tip not extending beyond posterior

FAKU 103752 n = 5 margin of gill cover. Numerous minute pores scattered on lacrimal and side of snout; relatively large sensory

Dorsal-fin rays XIV, 10 XIV, 9 or 10 pores along posterior orbital rim; ventral margin of

Anal-fin rays III, 5 III, 5 angular and dentary with net-like sensory canal under

Pectoral-fin rays 14 13 or 14 skin with numerous minute scattered pores. Ctenoid

Pored lateral-line scales 43 40-43 scales covering head and body; sides of snout, lac-

Scale rows above lateral line 7 6-8 rimal, maxilla, ventral surface of lower jaw and pectoral axil naked; about four rows of basal scales on base

Scale rows below lateral line 11 10-12 of dorsal- and anal-fin soft-rayed portions; pectoral-fin

Scale rows between 7 th dorsal-fin 5 5 base broadly covered with small ctenoid scales; cau-

spine base and lateral line dal-fin base with somewhat elongate basal scales. Fifth

Gill rakers (upper + lower limb = total) 5 + 9 = 14 4 or 5 + 10-14 = 14-18 dorsal-fin spine longest. Second anal-fin spine longest,

Standard length (mm) 73.7 44.5-102.1 its tip extending far beyond vertical through last anal-

Body depth at pelvic-fin origin 37.9 37.3-38.8 fin soft ray base; first soft ray longest. Eighth pectoral-

Body width 22.5 19.2-21.2 fin ray longest, its tip reaching vertical through twelfth dorsal-fin spine base. Pelvic-fin origin clearly poste-

Head length 41.9 40.4-45.0 rior to pectoral-fin origin; second soft ray longest, its

Orbit diameter 14.1 12.8-14.2 tip extending beyond anus when depressed. Caudal fin

Fleshy interorbital width 10.3 8.8-9.9 damaged but apparently with rounded contour.

Bony interorbital width 5.2 4.9-5.3

Snout length 8.1 7.1-8.6 Remarks

Postorbital length 24.1 21.4-25.7 The Mauritius example of C. vaigiensis was characterized by the anterior nostril with a low rim and

Upper-jaw length 16.1 15.3-16.8 large skin flap on the posterior margin; posterior mar-

Predorsal-fin length 28.1 28.8-30.2 gin of the preopercle with three large antrorse spines

Precaudal-fin length 75.1 76.0-81.0 ( Fig. 2 ), the dorsal fin origin positioned posteriorly on

Prepelvic-fin length 41.3 41.9-44.2 the head directly above the posterior edge of the pre-

1st dorsal-fin spine length 10.6 9.8-11.0 opercle; the second anal-fin spine robust and very long

2nd dorsal-fin spine length 19.3 15.5-17.6 (24.5% SL), its tip extending well beyond a vertical through the last anal-fin soft ray base, and the pelvic fin

3 rd dorsal-fin spine length 21.1 17.4-19.3 origin posterior to the pectoral-fin base, all characters

4 th dorsal-fin spine length 20.1 17.1-19.5 consistent with the original description and drawing of

5 th dorsal-fin spine length 20.2 16.7-19.4 the species ( Quoy and Gaimard, 1824: pl. 58, Fig. 1 )

12 th dorsal-fin spine length 14.4 13.6-14.8 and the description given by Gill (1999). Moreover, no

13th dorsal-fin spine length 13.1 12.1-13.3 clear differences in morphometric and meristic charac-

14th dorsal-fin spine length 11.5 11.3-13.0 ters (Tab. I) existed between the Mauritius specimen and comparative specimens from Japan and Malaysia.

1 st dorsal-fin soft ray length broken 16.6-19.9 Accordingly, the Mauritius specimen was identified as

1 st anal-fin spine length 7.4 7.2-8.7 C. vaigiensis .

2 nd anal-fin spine length 33.2 27.8-33.6

3 rd anal-fin spine length 21.7 19.2-23.4 DISCUSSION

1 st anal-fin soft ray length 23.5 21.8-25.9

Pectoral-fin length 33.0 31.8-34.3 The present specimen was collected by members of the 5 th Japanese Antarctic Research Expedition on

Pelvic-fin spine length 17.8 15.2-19.1 the RV Soya , during a stopover at Port Louise from

Longest pelvic-fin soft ray length 29.8 27.4-29.9 31 March to 2 April 1961. According to the previous

Caudal-fin length 28.4 24.5-28.9 occurrences, the specimen from Mauritius represents

Caudal-peduncle length 8.1 9.3-10.3 the first record of the species from that region ( Fig. 3 ).

Caudal-peduncle depth 10.5 10.7-11.3 The large geographical gap between Mauritius and the other distributional records of C. vaigiensis is unlikely to have resulted from chance ocean current transport, for although the North and South Equatorial Currents flow from east to west in the Indian Ocean, the species is believed to have a short pelagic larval stage during which it does not disperse far from the adult habitat ( Leis and Trnski, 1999). It is more plausible that C. vaigiensis is or was continuously distributed from the Andaman and Nicobar Islands to Mauritius via India, the Maldives and the Seychelles, in which case, further investigations of the marine fish fauna in the western Indian Ocean should result in further records of the species.

Acknowledgments. – The first author is deeply grateful to F. Tashiro, N. Nakayama, R. Misawa and other students of FAKU for their kind hospitality during his stay at their institute; and students and volunteers of KAUM for curatorial assistance. This study was supported in part by JSPS KAKENHI Grant Numbers JP26241027, JP24370041, JP23580259, and JP26450265; a JSPS Fellow grant (PD: 16J00047); the JSPS Core-to-Core Program, “Research and Education Network on Southeast Asian Coastal Ecosystems”; the “Coastal Area Capability Enhancement in Southeast Asia Project” of the Research Institute for Humanity and Nature, Kyoto, Japan; the “Biological Properties of Biodiversity Hotspots in Japan ” project of the National Museum of Nature and Science, Tsukuba, Japan; and “Establishment of Research and Education Network on Biodiversity and Its Conservation in the Satsunan Islands” project of Kagoshima University, adopted by the Ministry of Education, Culture, Sports, Science and Technology, Japan.

Figures

Figure 1. – Preserved specimen of Centrogenys vaigiensis [FAKU 103752, 73.7 mm SL, Mauritius].

Figure 2. – Head of Centrogenys vaigiensis [FAKU 103752, 73.7 mm SL, Mauritius]. Arrowheads indi- cate antrorse spines on preopercle margin.

Figure 3. – Distributional map of Centrogenys vaigiensis. The star indicates locality of FAKU 103752 (Mauritius). Shaded area indicates previously recorded distributional range.