Chascanopsetta lugubris Alcock, 1894

Amaoka, Kunio & Ho, Hsuan-Ching, 2019, The lefteye flounder family Bothidae (Order Pleuronectiformes) of Taiwan, Zootaxa 4702 (1), pp. 155-215 : 174

Chascanopsetta lugubris Alcock, 1894

Pelican flounder; ƛpłāľ

Figure 4A ; Table 5

Chascanopsetta lugubris Alcock, 1894:129 (Type locality: Bay of Bengal, Indian Ocean). Chen & Weng, 1965:60; Chen, 1969:215; Shen, 1983:35; Shen, 1984:447; Chen & Yu, 1986:820; Shen in Shen et al., 1993:568; Tongboonkua et al., 2018:179.

Chascanopsetta lugbris lugbiris: Amaoka & Yamamoto, 1984:209 ; Shen & Wu, 2012:749.

Specimens examined. NMMB-P001382 (4 of 10, 142.2–243.9), Dong-gang, no date ; NMMB-P1985 (10, 135.3– 186.0), Dong-gang, 13 Jun. 1983 ; NMMB-P5794 (2, 125.2–166.3), Dong-gang, 13 Mar. 2003 ; NMMB-P7386 (1, 144.7), Dong-gang, 3 Apr. 2004 ; NMMB-P8153 (4 of 5, 140.7–177.0), Dong-gang, 11 Jun. 2004 ; NMMB-P19174 (1 of 2, 202.0), Dong-gang, 3 Nov. 2011 ; NMMB-P22225 (2, 157.8–189.8), Dong-gang, 13 Mar. 2015 ; NMMB- P22260 (1, 73.8), Dong-gang, 11 Feb. 2015 ; NMMB-P25745 (1, 296.4), Dong-gang, 30 Mar. 2017 ; more specimens in NMMB-P collection.

Diagnostic Features. D 115–124; A 78–86; P 14–17; C 2+13+2=17; LLs 157–197; GR 0+1–3=1–3; vert. 17+38–40=55–57.

Body elongate elliptical, rather soft and flabby; greatest depth at posterior margin of abdominal cavity (24.9– 30.5% SL). Caudal peduncle narrow, its depth about 14–19 % of body depth. Head relatively large (19.8–22.7% SL); upper profile of head with slight concavity anterior of dorsal margin of lower eye. Snout blunt and short, its length about 2/3 of eye diameter. Eyes separated by narrowly flat space, its width about 1/3 to 1/4 of eye diameter.

Mouth very large, upper-jaw length 14.5–17.6% SL; maxilla extending well beyond posterior margin of lower eye; tip of lower jaw reaching a little beyond tip of upper jaw. Teeth on both jaws uniserial, slender; upper-jaw teeth small on posterior half; lower-jaw teeth curved inward and depressible, posteriormost teeth smaller than others. Gill rakers on lower limb, rudimentary. Scales on both sides very small, cycloid. Anterior rays of dorsal fin somewhat elongated, free from fin membrane except for base. First ray of anal fin connected with last ray of pelvic fin by narrow membrane. Pectoral fin on both sides slender, length on ocular side 10.3–14.6% SL. Caudal fin slender, with round tip.

Coloration. Ocular side of body uniformly dark brownish with many small irregularly arranged dark blotches; light blue on peritoneum; median fins dark without marking; paired fins paler than body. Blind side of body light brownish except for light blue peritoneum.

Size. Reaching 296 mm SL in Taiwan; up to 380 mm SL elsewhere ( Hensley & Amaoka, 2001).

Distribution. Widespread around Taiwan; Indian to Western Pacific oceans ( Amaoka & Yamamoto, 1984).

Remarks. This species had been regarded as two subspecies, C. lugubris lugubris from Pacific Ocean and C. lugubris danae from Atlantic Ocean ( Amaoka & Yamamoto (1984). But Munroe (2003) graded up to species based on clearly different counts of the gill rakers. Recently Tongboonkua et al. (2018) showed generic divergence between C. lugubris and C. danae . We followed their results, though it may be problematic in identification of species.

Caschanopsetta lugubris differs from C. prognatha in having the tip of the lower jaw slightly beyond the tip of the upper jaw and the lower-jaw length being shorter than HL ( Amaoka, 2016).

Figures

FIGURE 4. A. Chascanopsetta lugubris, NMMB-P25745, 296.4 mm SL. B–C. C. prognatha, NMMB-P30849, 198 mm SL, fresh (B) and preserved (C).