Chelon persicus Senou, Randall & Okiyama, 1995

Thieme, Philipp, Bogorodsky, Sergey V., Alpermann, Tilman J., Whitfield, Alan K., Freitas, Rui & Durand, Jean-Dominique, 2022, Contributions to the taxonomy of the mugilid genus Chelon Artedi (Teleostei: Mugilidae), with a major review of the status of C. persicus Senou, Randall & Okiyama, 1995, Zootaxa 5188 (1), pp. 1-42 : 10-16

Chelon persicus Senou, Randall & Okiyama, 1995

Persian Mullet

Figures 3–6 , Tables 2 & 3

Chelon persicus Senou et al., 1995: 235 (species account without designation of type material)— Senou et al. 1996: 72 (Doha fish market, Qatar, Arabian/Persian Gulf; formal species description); Al-Jufaili et al. 2010: 32 (Arabian/Persian Gulf).

Liza persicus — Carpenter et al. 1997: 203 (Arabian/Persian Gulf).

Planiliza persicus — Eagderi et al. 2019: 87 (Arabian/Persian Gulf).

Chelon sp. A — Durand & Borsa 2015: 8 ( South Africa).

Diagnosis (based on combined data from Senou et al. (1996) and present study). Second dorsal-fin rays 10; anal-fin rays 9–10 (usually 10); scales finely ctenoid, 33–36 in longitudinal series; predorsal scales with a single groove; caudal fin forked; upper lip with unicuspid, tiny, ciliform teeth in one row; ventral edge of preorbital notched at corner of mouth, posterior end of maxilla exposed when mouth closed; tip of pelvic fin is vertical to or behind origin of first dorsal fin; second vertebra with a pair of long, slightly curved, spine-like postzygapophyses; three short and three long unbranched pyloric caeca; pectoral-fin base silvery, without melanophores; reaches 275 mm SL.

Material examined. SMF 35897 [sample tissue KAU13-123 ], 194.2 mm SL, [ KAU13-124 ] 187.8 mm SL, [ KAU13-125 ] 188.9 mm SL, [ KAU13-135 ] 200.7 mm SL, Red Sea, Saudi Arabia, Al Wajh , lagoon, st 5, 13 June 2013 ; KAUMM 459 [ KAU13-136 ], 172.0 mm SL, [ KAU13-137 ] 188.4 mm SL, [ KAU13-138 ] 170.5 mm SL, Red Sea, Saudi Arabia, Al Wajh , lagoon, st 5, 13 June 2013 ; SMF 35898 [sample tissue KAU13-427 ], 66.7 mm SL, Red Sea, Saudi Arabia, Al Wajh , lagoon, st 15, 15 June 2013 ; Qatar Museum uncat [sample tissue QG17-83], 260 mm SL, Arabian / Persian Gulf , Qatar, off Doha, 03 December 2017 ; Qatar Museum uncat [sample tissue QG17-115], 275 mm SL, Arabian / Persian Gulf , Qatar, off Doha, 10 December 2017 ; SAIAB 83180, 106.2 mm SL, Western Indian Ocean, South Africa, KwaZulu-Natal Province, Cape Vidal , 15 May 2007 .

Description (based on material examined). Body relatively elongate, body depth at origin of first dorsal fin 3.4–3.7 in SL and caudal peduncle compressed. Head depth equal to or greater than head width, head length 4.1–4.3 in SL. Snout relatively blunt, subequal to orbit diameter, eye diameter 3.3–4.8 in head length. First dorsal fin with IV spines, second fin with 9–10 (rarely 9) rays. Origin of first dorsal fin closer to base of caudal fin than to tip of snout. Origin of second dorsal fin above first quarter of anal fin. Anal fin with III spines and 10 rays. Pectoral-fin rays 15–17. Tip of pectoral fin not reaching vertical at origin of first dorsal fin and not behind tip of pelvic-fin spine. If laid forward, pectoral fin not reaching anterior edge of eye. Tip of pelvic fin vertical to or behind origin of first dorsal fin. Caudal fin forked. Three supraneurals present and one each positioned between neural spines of vertebrae two and three, four and five, and six and seven. A pair of postero-dorsally elongated, slightly curved, and spine-like postzygapophyses present on second vertebra. Anterior first dorsal fin pterygiophore positioned posterior to neural spine of seventh vertebra. Anterior pterygiophores of second dorsal as well as anal fin positioned anterior to neural and haemal spine of thirteenth vertebra, respectively. Three interdorsal pterygiophores present. Three short and three long unbranched pyloric caeca attached to stomach.

Adipose eyelid covers only margins of eye; adipose tissue covers larger area anterior to eye reaching anterior nostril. Preorbital fills space between eye and mouth. Preorbital serrated along antero-ventral to posterior edge starting from above corner of mouth ( Fig. 3 ). Ventral edge of preorbital notched at corner of mouth. Postero-ventral corner of preorbital slightly rounded or truncate and reaching vertical behind anterior edge of eye. Corner of mouth vertical below anterior edge of posterior nostril. Maxilla reaching below corner of mouth, its posterior tip sigmoidal and visible when mouth closed. One row of minute, unicuspid, ciliform teeth present on upper lip. Lower lip with thin edge, directed horizontally forward, and large symphysial knob.

Body scales finely ctenoid ( Fig. 4 ), 33–35 scales in longitudinal series. Scales in transverse rows 11–12, predorsal scales to origin of first dorsal fin 11–13, to origin of second dorsal fin 21–23, circumpeduncular scales 16–18 ( Table 3 ). Predorsal scales anterior to first dorsal fin with single groove. Scales on head cycloid and arranged irregularly. Interorbital scales large, decreasing in size posteriorly. Dorsal scales on head forward to, or nearly to, posterior nostrils. Minute scales present on base of all fins, more prominent on the second dorsal, anal, caudal, and pectoral fins; covering approximately proximal third of first and second dorsal fin and anal fin. Two consecutive axillary scales lateral on each side of first dorsal fin, posterior axillary scales reaching behind base of last ray of first dorsal fin. Axillary scales also present lateral to origin of pelvic fin reaching about halfway along pelvic-fin spine. Very small axillary scale present above pectoral fin.

Fish coloration shown in Figs. 5 and 6 . Grey dorsally with greenish tinge, silvery below, without markings but with faint narrow grey stripes along centre of scale rows; pectoral-fin base silvery, without melanophores; caudal fin with narrow posterior black margin.

Distribution and habitat. Currently known from scattered localities in the Western Indian Ocean, including the Arabian/Persian Gulf, Red Sea, Mozambique and South Africa ( Fig. 2K ). This species forms schools in shallow coastal waters, including lagoons and estuaries.

Remarks. In the formal description of C. persicus it was noted that both the second dorsal and anal fin usually comprise nine fin rays ( Table 3 ). In the specimens from this study, we counted ten fin rays (only one specimen has nine fin rays in the second dorsal fin). This difference may be due to the general assumption that the last fin ray constitutes one deeply bifurcate ray or double ray. However, osteological studies on mugilids showed that two fin rays with separate bases are present ( Ghasemzadeh 2015; Thieme & Moritz 2020). We were also able to observe the separate bases in specimen SMF 35897 [KAU13-125].

The species name was first included in the monograph on coastal fishes of Oman ( Randall 1995) accompanied by a species account (without designation of types), and was later formally described by Senou et al. (1996). We follow the former publication and subsequent Catalog of Fishes ( Fricke et al. 2022) regarding the date of first mention of C. persicus .

Comparisons. Chelon persicus can be distinguished from other Chelon species by the number of scales in the longitudinal series (33–36), while congeners have more than 40 scales except C. dumerili which has 34–39 and C. bandialensis which has 32–33 scales ( Fischer et al. 1981; Thomson & Luther 1983; Harrison 2016). Chelon dumerili differs from C. persicus in having multiple grooves on its predorsal scales while C. persicus only has a single groove ( Senou et al. 1996).

Chelon persicus is externally similar to the sympatric Planiliza macrolepis (Smith, 1846) but differs by scales dorsally on the head reaching forward to posterior nostrils versus scales usually extending beyond anterior nostrils in P. macrolepis . Teeth on the upper lip of C. persicus are tiny and ciliform, usually without a second row, whereas for P. macrolepis the upper lip has an outer row of very small, well-spaced, peg-like teeth and an irregular inner row of small teeth, well separated from the outer row. The pectoral-fin base is whitish and unpigmented in C. persicus but pigmented with melanophores, often with a golden sheen, in P. macrolepis .

Internally C. persicus differs from all other Chelon species in having a pair of long, spine-like postzygapophyses on the second vertebrae, instead of a pair of short and hook-like postzygapophyses. Chelon persicus also differs from C. auratus , C. bispinosus , C. labrosus and C. ramada by the presence of short and long pyloric caeca versus pyloric caeca of subequal length in these species.

Figures

FIGURE 2. Distribution ranges of Chelon spp. inferred from GBIF occurrence data obtained from geolocalised preserved specimens (blue dots) as well as DNA barcodes available in BOLD (consultation February 2022) plus some unpublished data (red dots, Appendix 1). Doubtful GBIF reference are pointed by a “?”. A: Chelon auratus BIN BOLD:AAD7360; B: Chelon ramada BIN BOLD:AAD5443; C: Chelon labrosus BIN BOLD:AAE2670; D: Chelon saliens BIN BOLD:AAF6190; E: Chelon bispinosus BIN BOLD:AEO1527; F: Chelon bandialensis BIN BOLD:ACC0109; G: Chelon dumerili (GBIF data correspond to Chelon dumerili spp.) BIN BOLD:ACC0658; H: Chelon sp. B (GBIF data correspond to Chelon dumerili spp.) BIN BOLD: AAD7493; I: Chelon richardsonii BIN BOLD:AAD7487; J: Chelon tricuspidens BIN BOLD:AAF6205; K: Chelon persicus BIN BOLD:AAC0698.

FIGURE 3. Head of Chelon persicus. A & B: SMF 35897 [KAU13-125], 189 mm SL, with important characters marked, Asterisk = single row of minute teeth on upper jaw.

FIGURE 4. Scales of Chelon persicus (SMF 35897 [KAU13-125], 189 mm SL) stained with alizarin red. A: body scale from the anterior trunk above the pectoral fin; B: predorsal scale from midline anterior to the first dorsal fin; C. interorbital scale. Scale bar = 500µm.

FIGURE 5. Fresh specimens of Chelon persicus. A: SMF 35898 [KAU13-427], 66.7 mm SL, Al Wajh, Saudi Arabia, Red Sea; B: SMF uncat [QG17-83], 260 mm SL, Qatar, Arabian/Persian Gulf; C: SMF uncat [QG17-115], 275 mm SL, Qatar, Arabian/ Persian Gulf. Photos by S.V. Bogorodsky.

FIGURE 6. Detailed photographs of the head of fresh specimens of Chelon persicus. A: SMF uncat [QG17-83], 260 mm SL, Qatar, Arabian/Persian Gulf; B: detailed photographs of the head of SMF uncat [QG17-115], 275 mm SL, Qatar, Arabian/ Persian Gulf. Photos by S.V. Bogorodsky.

Tables

TABLE 3. Meristic characters of examined specimens in comparison to Chelon persicus (Senou et al. 1996). Asterisk = In Senou et al. (1996) the last fin ray presumably was counted as one bifurcated ray, while in this study two separate rays were counted.

	Chelon persicus	SAIAB 83180	SMF 35897 [KAU12-123]	SMF 35897 [KAU13-124]	SMF 35897 [KAU13-125]	SMF 35897 [KAU13-135]
Longitudinal scale rows 34-36		35	33	34	34	34
Dorsal-fin rays *	IV + 9	IV + 10	IV + 10	IV + 10	IV + 10	IV + 10
Pectoral-fin rays	15-17	16	16	16	16	16
Anal-fin rays *	III,8-9	III, 10	III,10	III,10	III,10	III,10
TV	11	-	12	12	12	-
PD1	-	-	13	12	11	-
PD2	-	-	23	22	21	-
CP	-	-	17	17	18	-
Continued.
	KAUMM 459 KAUMM 459 KAUMM 459 SMF 35898 SMF uncat [KAU13-136] [KAU13-137] [KAU13-138] [KAU13-427] [QG17-83]					SMF uncat [QG17-115]
Longitudinal scale rows	34	35	34	34	34	35
Dorsal-fin rays *	IV + 10	IV + 9	IV + 10	IV + 10	IV + 10	IV + 10
Pectoral-fin rays	16	15	17	17	16	16
Anal-fin rays *	III,10	III,10	III,10	III,10	III,10	III,10
TV	11	11	-	11	11	11
PD1	11	12	-	11	-	-
PD2	21	23	-	23	-	-
CP	16	18	-	18	16	-