First records of the seamoth, Pegasus nanhaiensis (Actinopterygii: Syngnathiformes: Pegasidae), from the southern South China Sea, with notes on fresh coloration Author Akaike, Takahiro Graduate School of Agriculture, Forestry and Fisheries, Kagoshima University, Kagoshima, Japan Author Chungthanawong, Sirikanya Natural History Museum, National Science Museum, Pathumthani, Thailand Author Motomura, Hiroyuki Kagoshima University Museum, Kagoshima, Japan motomura@kaum.kagoshima-u.ac.jp text Acta Ichthyologica et Piscatoria 2022 2022-01-11 52 1 1 8 http://dx.doi.org/10.3897/aiep.52.78260 journal article http://dx.doi.org/10.3897/aiep.52.78260 1734-1515-1-1 5AE59D2D6698424BA9592A4E017ED91C 201B23ED06C652C8AB09E430D4774B59 Pegasus nanhaiensis Zhang, Wang et Lin, 2020 Figs 1 , 2 , 3 , 4 Pegasus laternarius (not of Cuvier 1829 ): Palsson and Pietsch 1989 : 23, fig. 11 (Ko Kradat, Trat Province, eastern Gulf of Thailand, southern South China Sea); Matsunuma 2013 : 68, unnumbered figs. (northern Gulf of Thailand, southern South China Sea; incorrectly reported as Cuvier 1816). Pegasus nanhaiensis : Zhang et al. 2020 : 523, figs. 1, 3A, 3C, and 4A (type locality: off Yangjiang, China; paratype localities: off Yangjiang and Beihai, China, northern South China Sea). Spinipegasus laternarius (not of Cuvier 1829 ): Hibino 2021 : 14, unnumbered figs. (Bidong Island, off east coast of Malay Peninsula, southern South China Sea; incorrectly reported as Cuvier 1816). Material examined. Three specimens from the northern Gulf of Thailand : KAUM-I. 47679, female, 45.5 mm SL, KAUM-I. 47680, male, 56.9 mm SL, KAUM-I. 47681, male, 49.7 mm SL, trawl, purchased at a fish market in Maha Chai , Samut Sakhon Province , Thailand , 6 July 2012 (originally deposited in Kasetsart University) . Description. Measurements are given in Table 1 . Body depressed, encased in bony plates. Eyes not visible in ventral view. Rostrum of male long, club-shaped, with many small surface spines; that of female very short, pointed. Mouth small, inferior, toothless. Gill opening restricted to small dorsolateral hole behind head. Two rows each with two small tubercles on dorsum of head. Carapace comprising three pairs of dorsal plates (d1-3), four pairs of dorsolateral plates (dl1-4), paired superior pectoral-fin plates (pp.s.), and two paired extralateral plates (el1-2); rounded hump-like tubercles on each dorsal plate (d1-3); small posteriorly directed tubercles on lateral edges of each dorsolateral plate (dl1-4). [KAUM-I. 47680 with hook-shaped tubercle between paired dorsal plates (d2); absent in KAUM-I. 47679 and 47681]. Plastron comprising five paired ventrolateral plates (vl1-5), paired gular plates (g), pectoral plates (p), ventral plates (v), anal plates (a) and inferior pectoral-fin plates (pp.i.) and an unpaired pre-anal plate (ip). Anus located between preanal plate and tail ring I. KAUM-I. 47679 with 6 inwardly directed spines (7 and 5 in KAUM-I. 47680 and 47681, respectively) on dorsal surface of ventrolateral plate (vl1). Small central tubercles on each pectoral and ventral plate; interventral and pre-anal plates with bulge, the latter plate with posteriorly directed tubercle; small, posteriorly directed tubercles on lateral edges of each vl2-vl4. Tail elongate, with 11 tail rings (I-XI); 9th and 10th tail rings fused together, anterior 8 rings mobile; small, posteriorly directed tubercles on corners of each tail ring, their tips sharply pointed; tubercles smaller on posterior tail rings; anteriorly directed spines on anterior of tubercles on tail rings IX, X, and XI; two paired caudolateral plates overlapping junctions between tail rings II and III and IV and V; dorsal surface of last tail ring lacking spine. Wing-like pectoral fins large, inserted horizontally, with 11 rays (10 and 12 rays on left and right side, respectively, in KAUM-I. 47679), 5th ray stout, thicker than other rays. Pelvic fins with 1 spine and 2 rays; each pelvic fin separated without membrane, inserted into an unpaired interventral plate; first spine very long, extended posteriorly. Dorsal and anal fins short, each with 5 soft rays, extending from center of dorsal and ventral tail ring II to center of tail ring IV, respectively. Caudal fin with 8 unbranched rays. Table 1. Measurements of Pegasus nanhaiensis .

Character	This study		Zhang et al. (2020)
	Northern Gulf of Thailand, southern South China Sea		China, northern South China Sea
	Males n = 2	Female n = 1	Holotype	Paratypes
			male	males	females
			n = 1	n = 11	n = 5
-	[mm]
Standard length (SL)	49.7-56.9	45.5	61.7	47.1-57.8	53.8-62.3
Precaudal length (PCL)	53.8-61.4	46.8	67.4	52.3-64.4	55.0-62.9
-	[% of SL]
Carapace length	47.5-49.3	53.9	47.1	48.6-53.2	51.4-54.5
Tail length	48.5-51.7	48.9	49.8	46.7-52.8	45.1-49.8
Prepectoral width	40.9-41.4	44.8	40.8	40.3-46.0	44.4-47.5
Interpectoral width	29.7-30.3	35.7	29.0	29.7-34.9	34.0-36.3
Carapace width	29.7-30.7	37.0	29.9	28.8-34.7	34.8-37.0
Body depth	18.7-19.7	19.8	17.9	16.5-20.9	16.1-20.0
Rostrum length	14.0-15.7	6.9	13.8	13.9-17.4	4.8-6.3
Rostrum width at tip	4.9-5.0	1.6	4.8	3.0-4.3	1.0-1.6
Orbit length	8.9-10.2	10.1	8.9	9.2-11.3	9.7-10.8
Interorbital width	9.5-11.2	10.7	9.7	9.1-11.2	8.7-10.7
Head width	26.6-27.7	30.5	26.4	26.7-31.8	30.2-32.4
Length of 5th pectoral ray	32.9-34.4	36.8	33.6	30.9-40.3	35.1-38.3
Height from dorsal to anal fins	10.4-10.7	10.2	11.3	10.2-12.8	10.0-12.2
Rostrum tip to pelvic fin length	50.9-51.2	45.8	49.6	49.5-53.6	41.2-46.6
Rostrum tip to anal fin length	66.8-67.0	65.3	65.3	67.0-66.4	67.0-73.1
Length from base of pectoral fin to pelvic fin	27.7-28.0	29.2	27.5	28.4-31.4	28.4-31.4

Coloration when fresh (Figs 1A-1B ). Dorsal body surface pale yellow to dark yellowish-brown with numerous reddish-brown to black spots; clear hexagonal patterns apparent on dorsal plate (d1-3) and dorsolateral plate (dl1-4), with distinct boundaries. Blurred black blotches on rounded hump-like tubercles on dorsal plates in KAUM-I. 47679 (absent in KAUM-I. 47680). Dorsal surface of ventrolateral plate (vl1) whitish. Base color of dorsal surface tail rings I-IV, posterior half of VII and VIII brown; that of V-VI, anterior of VII and IX-XI white. Numerous reddish-brown spots on dorsal surface of tail rings I-IV, brown spots on dorsal tail rings VI-VII in KAUM-I. 47680 (reddish to brown spots on I-VIII in KAUM-I. 47679). Base color of pectoral-fins whitish; 2-9 brown blotches on each ray. Pelvic-fins white; small brown blotches on each ray. Dorsal and caudal fins translucent white, small brown blotches on each ray. Figure 1. Dorsal views of Pegasus nanhaiensis from the northern Gulf of Thailand. A : KAUM-I. 47680, male, 56.9 mm SL; B , KAUM-I. 47679, female, 45.5 mm SL. Color in alcohol (Figs 2A-2B ). Dorsal body surface and tail rings light reddish-yellow. Faint yellowish-brown spots on dorsal body and tail rings I-IV in KAUM-I. 47680 (dorsal body and tail rings I-VIII in KAUM-I. 47679). Margins of majority of dorsal plates white (some slightly yellowish-brown). Each fin translucent white. Figure 2. Dorsal views of preserved specimens of Pegasus nanhaiensis from the northern Gulf of Thailand. A : KAUM-I. 47680, male, 56.9 mm SL; B , KAUM-I. 47679, female, 45.5 mm SL.