Parabothus polylepis ( Alcock, 1889 )

Amaoka, Kunio & Ho, Hsuan-Ching, 2019, The lefteye flounder family Bothidae (Order Pleuronectiformes) of Taiwan, Zootaxa 4702 (1), pp. 155-215 : 200-202

Parabothus polylepis ( Alcock, 1889)

Manyscaled flounder; ŧâfľ

Figure 8F ; Table 11

Arnoglossus polylepis Alcock, 1889:290 (Type locality: off Sri Lanka)

Parabothus polyleis: Norman, 1931:600 .

Specimen examined. NMMB-P26403 (1 female, 119.7), Ke-tzu-liao, 27 Jun. 2017 .

Diagnostic features. D 89; A 67; P 10; C 2+13+2=17; LLs 86; GR 0+8=8; vert. 10+27=37.

Body elliptical, deepest slightly anterior of middle of body (46.2% SL). Head longer than half of body depth (27.7% SL); front profile of head with shallow concavity anterior of ventral margin of lower eye. Snout much shorter than eye diameter. No rostral spine on snout tip. Eye diameter shorter than upper-jaw length. Orbital spine absent. Interorbital space narrow, deeply concave, its width narrower than eye diameter, 4% HL (based on one female only).

Mouth moderate large, upper-jaw length 9.7% SL; maxilla extending to slightly beyond anterior margin of lower eye. Teeth on both jaws uniserial, moderately conical, some pairs of anterior teeth enlarged; lateral teeth on lower jaw somewhat stronger than those on upper jaw. Gill rakers on lower limb moderate large in size, smooth; absent on upper limb.

Scales on ocular side ctenoid with moderately long ctenii; cycloid on blind side. Pectoral fin on ocular side moderate large, not elongate (16.6% SL).

Coloration. Ocular side of body dark brown with an obtuse, large dark blotch at junction of straight and curved sections of lateral line, and a dark obtuse blotch on middle section of straight lateral line; a conspicuous black blotch on dorsal fin above anterior margin of upper eye; a series of large faint rings along dorsal and ventral edges of body; vertical fins with faint dark spots at base; pectoral fin with three indistinct dark cross bars; pelvic fin with a black spot on membrane between third and fourth rays; body on blind side grayish white.

Size. Reaching 120 mm SL in Taiwan; up to 130 mm SL in Sri Lanka ( Norman, 1934).

Distribution. Southwestern Taiwan off Ke-tzu-liao at depths less than 100 m; Sri Lanka at depths 59–64 m ( de Bruin et al., 1995).

Remarks. This species was first recorded from Taiwan on the bases of a single female specimen. This species can be separated from the three other Taiwanese species of Parabothus in having fewer dorsal- and anal- fin rays and vertebrae. Currently, no male specimen was examined by the authors and the characters of males are unknown. This species may exhibit sexually dimorphism and ontogenetic changes on interorbital width and presence or absence of rostral spine as other congeners.

Figures

FIGURE 8. A. Neolaeops microphthalmus, NMMB-P 20986, 110 mm SL. B–C. Parabothus coarctatus, NMMB-P13151, male, 188.5 mm SL (B) and NMMB-P13149, female, 188.9 mm SL (C). D–E. Parabothus kiensis, NMMB-P18021, male, 133.0 mm SL (D) and NMMB-P30894, female, 157 mm SL (E). F. Parabothus polylepis, NMMB-P26403, female, 119.7 mm SL.

Tables

TABLE 11. Frequency of six meristic data of four Parabothus species in Taiwan.

Dorsal-fin rays
	n	89	//	98	99	100	101	102	103	104	105	106 107 108			109	110	111	112	113	114	115	116	117
P. coarctatus	6															1	0	1	0	1	0	1	2
P. kiensis	7					1	0	0	0	0	0	1	2	0	0	0	1	1	0	1
P. polylepis	1	1
P. taiwanensis	20			2	0	2	0	0	0	4	2	3	5	1	0	1
Anal-fin rays
	n	67	//	77	78	79	80	81	82	83	84	85	86	87	88	89	90	91	92	93	94	95
P. coarctatus	6															1	0	0	1	3	0	1
P. kiensis	7										1	0	2	0	2	2
P. polylepis	1	1
P. taiwanensis	20			1	3	1	2	2	0	4	1	3	1	2
		Pectoral-fin rays							Gill rakers (upper+lower)										Vertebrae (precaudal+caudal)
	n	10	11	12	13	14			n	0	+	7	8	9			n	10	+	27	28	29	30	31	32	33
P. coarctatus	6			1	4	1			5	5			1	4			6	6								6
P. kiensis	7			2	5				7	7		2	1	4			7	7						3	4
P. polylepis	1	1							1	1			1				1	1		1
P. taiwanensis	20		2	7	9	2			20	20		15	5				20	20			1	9	10
Lateral-line scales
	n	61	62	63	64	65	66	67	//	78	79	80	81	82	83	84	85	86	87	88	89	90	91	92	93	94	95
P. coarctatus	6																		1	0	0	0	0	1	0	1	3
P. kiensis	7									1	0	2	3	0	1
P. polylepis	1																	1
P. taiwanensis	20	5	3	3	2	3	1	3