Plectorhinchus pictus (Thunberg, 1792)

Habib, Kazi Ahsan, Islam, Md Jayedul, Nahar, Najmun, Rashed, Mohammad, Neogi, Amit Kumer & Russell, Barry, 2021, Grunts (Actinopterygii: Perciformes: Haemulidae) of Bangladesh with two new distributional records from the northern Bay of Bengal assessed by morphometric characters and DNA barcoding, Acta Ichthyologica et Piscatoria 51 (3), pp. 299-309 : 299

Plectorhinchus pictus (Thunberg, 1792)

Local common name: futki datina (Bangla) Fig. 2a

Material examined.

Bangladesh • 2 specimens; F1804SM-21 (110 mm SL), Cox's Bazar , Bay of Bengal, Saint Martin’s Island, 20°36'39.6"N, 92°19'37.2"E, 20 April 2018, Amit Kumer Neogi, GenBank: MK340608 ; F1804SM-22(105 mm SL), Cox's Bazar , Bay of Bengal, Saint Martin’s Island, 20°36'39.6"N, 92°19'37.2"E, 20 April 2018, Amit Kumer Neogi, GenBank: MK340609 .

Diagnostic characters.

Meristics: D-X, 23; P1-17; P2-I, 5; A-III, 7; C-18

Body deep and compressed. Profile of snout steep; lips fleshy; chin with six pores, but no median pit; lower jaw without longitudinal groove at midline. Caudal peduncle slender and long; scales small, ctenoid. Color varying greatly with size. Juveniles dark brown to black above, 4 broad longitudinal black bands on the body, silvery yellow below; dorsal and caudal fins yellow with black patches and broken stripes (Fig. 2a ).

Remarks.

This species has previously been included by the majority of authors in the genus Diagramma Oken, 1817, but recent phylogenetic analyses ( Sanciangco et al. 2011; Tavera et al. 2012; Tavera et al. 2018) have shown that Diagramma (including type species D. pictus ) is deeply nested within Plectorhinchus (and sister to its type species Plectorhinchus chaetodonoides Lacepède, 1801), and Tavera et al. (2018) have proposed that Diagramma should be considered a junior synonym of Plectorhinchus Lacepède, 1801. As pointed out by Parenti (2019), however, accepting Plectorhinchus as the senior synonym of Diagramma creates several nomenclatural problems: Plectorhinchus pictus (Tortonese, 1936) becomes a secondary homonym of P. pictus (Thunberg, 1792), and the next available name for P. pictus (Tortonese) is Plectorhinchus cinctus punctatatus Fang, 1942 (see Fricke et al. 2021b) which is secondarily preoccupied in Plectorhinchus by Diagramma puncatatum Cuvier, 1830 (see Fricke et al. 2021b). This problem was long ago recognized by Whitley (1951), who anticipated Diagramma as a synonym of Plectorhinchus and accordingly proposed the name Plectorhinchus fangi Whitley, 1951, as a replacement for P. cinctus punctatus Fang (a species not yet recorded from the Bay of Bengal). Thus, we regard Plectorhinchus pictus (Thunberg, 1792) as the correct name for the species described here from Bangladesh.

Specimens of P. pictus from the Bay of Bengal are part of a distinct subspecies, Plectorhinchus pictus cinerascens Cuvier, 1830-one of five geographically separate subspecies recognized by Johnson et al. (2001, as Diagramma ): P. pictus pictus (Thunberg), P. pictus labiosum Macleay, P. pictus punctatum Cuvier, and P. pictus centurio Cuvier). Plectorhinchus pictus , subspecies Plectorhinchus pictus cinerascens of Johnson et al. (2001) differs from all others in the configuration of the body stripes of juveniles, size of spots, and nature of the lines on the cheeks and operculum of large juveniles to small adults. Juveniles of about 150 mm TL often have broad, clearly defined body stripes, not yet beginning to break into broken lines or numerous spots; and progress from a striped to a fully spotted phase at 180-240 mm TL ( Johnson et al. 2001: fig. 5). A more detailed genetic study is necessary to determine whether this geographically distinct color variety should be afforded separate species recognition ( Johnson et al. 2001).

Distribution.

Plectorhinchus pictus cinerascens , occurs from the Bay of Bengal to the Arabian/Persian Gulf ( Johnson et al. 2001).

Conservation status.

Not yet assessed, not listed in the IUCN Red List of Threatened Species (https://www.iucnredlist.org/species/123439745/123494892).

Figures

Figure 2. Lateral view of collected specimen, a. Plectorhinchus pictus, subspecies Plectorhinchus pictus cinerascens (F 1804 SM- 22; 105 SL mm), striped juvenile phase; b. Plectorhinchus macrospilus (F 1803 SM- 67; 335 mm SL); c. Plectorhinchus andamanensis, (F 1803 SM- 19; 137 mm SL); d. Pomadasys argenteus (F 1602 Sb- 01; 132 mm SL).