Introduction

The genus Thrissina Jordan and Seale 1925, an Indo-Pacific genus of marine and/or brackish water anchovies (Clupeiformes: Engraulidae), previously regarded as Thryssa Cuvier 1829 (Kottelat 2013), includes 27 valid species (Roberts 1978; Wongratana 1983, 1987; Whitehead et al. 1988; Wongratana et al. 1999; Hata and Motomura 2019; Hata and Koeda 2020; Hata et al. 2020; this study). Formerly included in the subfamily Engraulinae (Whitehead 1985; Whitehead et al. 1988), Thrissina has been shown by molecular studies to be more closely related to Coilia Gray 1830 than to other genera included in the subfamily (e.g., Encrasicholina Fowler 1938, Engraulis Cuvier 1816, and Stolephorus Lacepède 1803) and is now considered part of the subfamily Coilinae, together with (at least) Coilia, Lycothrissa Günther 1868, and Setipinna Swainson 1839 (Lavoué et al. 2010, 2017). Moreover, since Thrissina was shown to be polyphyletic by Lavoué et al. (2017), further studies of species’ relationships within the genus are warranted.

During a revisionary study of Thrissina, a number of specimens of the genus from Pakistan were identified as new to science, although similar to Thrissina whiteheadi (Wongratana 1983) in sharing a rather long maxilla, extending posteriorly beyond the opercular margin but not reaching to the pectoral-fin insertion, enlarged teeth on both jaws, similar numbers of ventral scutes and absence of the first supramaxilla. The specimens are described here as a new species of Thrissina. In addition, T. whiteheadi is redescribed.

Materials and methods

Counts and proportional measurements generally followed Hata and Motomura (2019); transverse scale counts did not include ventral and predorsal scutes. All measurements were made with digital calipers to the nearest 0.01 mm. Standard length was abbreviated as SL. Counts and measurements, expressed as percentages of SL, are given in Tables 1 and 2. Institutional codes follow Sabaj (2019). Nomenclature and authorship of the genus Thrissina follow Kottelat (2013).

Table 1 Meristics of specimens of Thrissina whiteheadi and T. supra sp. nov.
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Table 2 Morphometrics of specimens of Thrissina whiteheadi and T. supra sp. nov.
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Thrissina whiteheadi (Wongratana 1983)


(English name: Whitehead’s Thryssa)


(Fig. 1; Tables 1, 2, 3, 4)

Fig 1
figure 1

a Fresh specimen of Thrissina whiteheadi, BPBM 30365, 204.8 mm SL, collected from Dammam, Saudi Arabia, (J. Randall, photo); b–d holotype of Thryssa whiteheadi, BMNH 1920.3.3.192, 107.8 mm SL, Basra, Iraq (lateral, dorsal, and ventral views, respectively)

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Table 3 Frequency distribution of longitudinal series scale rows in Thrissina whiteheadi and T. supra sp. nov.
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Table 4 Frequency distribution of branched anal-fin rays in Thrissina whiteheadi and T. supra sp. nov.
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Thryssa mystax (not of Bloch): Kuronuma and Abe 1972: 48, pl. 2 (Sulaibikhat, Kuwait); Kuronuma and Abe 1986: pl. 4 (Sulaibikhat, Kuwait).

Thryssa whiteheadi Wongratana 1983: 403, fig. 22 (type locality: Basra, Iraq; paratype localities: Bushire, Iran); Whitehead et al. 1988: 446, unnumbered fig. (Persian Gulf); Randall 1995: 73, fig. 143 (Dammam, Saudi-Arabia); Hussain et al. 2009: 177 (Al-Hammar Marshes, southeastern Iraq); Al-Faisal 2012: 151 (Iraq); Nasir 2015: 60 (Shatt Al-Basrah, Iraq); Mohamed et al. 2017: 20 (Garmat Ali River, Iraq); Al-Faisal and Mutlak 2018: 166, table 1 (Iraqi marine waters); Afrand et al. 2020: 376, fig. 5 (Tiab, Iran).


Holotype. BMNH 1920.3.3.192 (Fig. 1b–d), 107.8 mm SL, Basra, Iraq, coll. by C. Christy.

Paratypes. BMNH 1920.3.3.183–191, 9 of 18 specimens, 56.5–141.0 mm SL, Bushire, Iran.

Non-type specimens (4 specimens, 138.5–204.8 mm SL): BMNH 1982.9.6.122–124, 3 specimens, 138.5–141.9 mm SL, Kuwait, Kuwait; BPBM 30365, 204.8 mm SL, Dammam Fish Market, Saudi Arabia, Persian Gulf.

Diagnosis. A species of Thrissina with the following combination of characters: upper jaw relatively long, its posterior tip slightly beyond opercle posterior margin, but not reaching pectoral-fin insertion; first supramaxilla absent; teeth on both jaws robust, enlarged; dorsum without dark lines in preserved specimens; dark black blotch behind upper part of gill opening absent or indistinct in preserved specimens; dorsal fin with 9–11 (modally 10) branched rays; anal fin with usually 39–42 (rarely 43, modally 40) branched rays; pectoral fin with 11 or 12 (modally 12) branched rays; transverse scales 10 or 11 (11); scale rows in longitudinal series 40–42 (42); gill rakers 12–15 (13) in upper series on first gill arch, 18–21 (19) in lower series, 30–34 (rarely 36, modally 32) in total; gill rakers 10–13 (modally 12) in upper series on second gill arch, 18–21 (19) in lower series, 29–34 (31) in total; gill rakers 8–10 (8) in upper series on third gill arch, 10–13 (11) in lower series, 19–23 (19) in total; gill rakers 6–8 (7) in upper series on fourth gill arch, 8–11 (10) in lower series, 14–19 (17) in total; snout short, 3.1–3.6% SL; pelvic fin short, 7.7–9.0% SL; mandible short, 15.4–17.2% SL; pelvic-fin insertion to anal-fin origin 19.1–24.2% SL.

Description. Data for holotype presented first, followed by other specimen data in parentheses (if different). Body strongly compressed laterally, greatest depth at dorsal-fin origin. Dorsal profile of head and body gently elevated from snout tip to dorsal-fin origin, gradually lowering to uppermost point of caudal-fin base. Ventral profile of body dropping from mandibular tip to pelvic-fin insertion, gently rising to anal-fin base end, subsequently parallel to body axis to lowermost point of caudal-fin base. Abdomen covered by 16 (15 or 16) and 10 sharp needle-like scutes from isthmus to pelvic scute, and pelvic scute to anus, respectively. Anus just anterior to anal-fin origin. Caudal peduncle compressed, its depth greater than orbit diameter. Pectoral-fin insertion slightly anterior to posterior tip of opercle. Uppermost ray of pectoral fin unbranched, other rays branched. Posterior tip of pectoral fin pointed, slightly beyond pelvic-fin insertion. Upper, lower, and posterior margins of pectoral fin nearly straight. Pelvic-fin insertion anterior to dorsal-fin origin. Posterior tip of depressed pelvic fin not reaching anus. Anteriormost ray of pelvic fin unbranched, other rays branched. Dorsal-fin origin anterior to anus. Anterior three rays unbranched. Single spine-like scute located just anterior to dorsal-fin origin. Anal-fin origin just below origin of ninth (seventh to eleventh) dorsal-fin ray [in largest (204.8 mm SL] specimen, posterior to dorsal-fin base end). Lower contour of anal fin lowering from fin origin to fifth fin ray tip, almost parallel to ventral profile of body. Caudal fin forked. Head compressed. Snout length much less than orbit diameter. Snout tip rounded, at about horizontal level of upper margin of eye. Eye round, covered with adipose eyelid, lateral on head, dorsal to horizontal through pectoral-fin insertion, visible in dorsal and ventral views. Pupil round. Orbit elliptical. Nostrils close to each other, anterior to anterior margin of orbit and above horizontal through midline of body. Posterior margin of preopercle convex, smooth. Subopercle with rounded posterior margin. Opercular membrane without serrations. Pseudobranchial filaments present, covered with fleshy membrane. Interorbital space flat. Mouth large, inferior, below body axis, extending backward beyond posterior margin of eye. Mandible slender, much shorter than maxilla. Maxilla long, posterior tip pointed, slightly beyond posterior margin of opercle, but not reaching pectoral-fin base. First supramaxilla absent. Robust enlarged conical teeth in single row on both jaws. Single row of small conical teeth on palatine. Several conical teeth on vomer. Small conical teeth patch on pterygoid. Several rows of conical teeth on upper edges of basihyal and basibranchial. No teeth on dorsal surface of hyoid. Gill rakers long, slender. Each serra on gill rakers almost same size. Gill membrane on each side joined distally, most isthmus muscle exposed (not covered by gill membrane). Scales absent on head and fins. Lateral line absent. Scales cycloid, thin, deciduous.

Coloration of fresh specimen. Based on a color photograph of BPBM 30365 (204.8 mm SL, Dammam Fish Market, Saudi Arabia, Persian Gulf; Fig. 1a). Body uniformly whitish-silver, dorsum dark. Snout semi-transparent, yellowish. No dark blotch on body. All fins (including fin rays and fin membrane) semi-transparent, white. Posterior part of caudal fin yellowish. Anterior margin of dorsal fin and dorsal margin of caudal fin dusky. Iris gold, pupil black.

Coloration of preserved specimens. Head and body almost uniformly silver, dorsum pale brown. Numerous melanophores densely scattered on dorsum, not forming line (Fig. 1c). No dark blotch on body (some paratypes with indistinct black blotch behind upper part of gill opening). All fins pale, semi-transparent. No melanophores on pectoral, pelvic, and anal fins. Melanophores scattered along dorsal- and caudal-fin rays.

Distribution. Known only from the Persian Gulf (Fig. 2) (distribution details discussed under Remarks). According to Hussain et al. (2009), Nasir (2015), and Mohamed et al. (2017), the species inhabits low-salinity water in inland marshes and estuaries in Iraq. The species is probably not distributed in Oman (see Remarks).

Fig. 2
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Distributional records of Thrissina whiteheadi (closed triangles, based on specimens examined in this study) and T. supra sp. nov. (closed circle, based on specimens examined in this study)

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Comparisons. The enlarged, robust teeth on both jaws in T. whiteheadi distinguishes that species from other congeners, except Thrissina dayi (Wongratana 1983), Thrissina gautamiensis (Babu Rao 1971), Thrissina spinidens (Jordan and Seale 1925), and Thrissina supra sp. nov. (Roberts 1978; Wongratana 1983, 1987; Whitehead et al. 1988; Wongratana et al. 1999; Hata and Motomura 2019; Hata and Koeda 2020; Hata et al. 2020; this study). Thrissina whiteheadi differs from T. dayi and T. gautamiensis in lacking the first supramaxilla (vs. small first supramaxilla present in the latter two species), and the dorsum without dark lines (vs. distinct paired dark lines on dorsum). Thrissina whiteheadi is further distinguished from T. dayi by a shorter maxilla (posterior tip slightly beyond opercular margin in T. whiteheadi vs. reaching pectoral-fin insertion in T. dayi) and higher counts of lower gill rakers on the first gill arch (18–21 vs. 14–18). The number of branched anal-fin rays also separate T. whiteheadi (usually 39–42, rarely 43) and T. gautamiensis (34–37, rarely 33). Thrissina whiteheadi differs from T. spinidens in having more lower gill rakers on the first gill arch (18–21 in T. whiteheadi vs. 13–15 in T. spinidens) and a lower total abdominal scute count (25 or 26 vs. 27–29) (Wongratana 1983; Whitehead et al. 1988; this study). Comparisons of T. whiteheadi with T. supra sp. nov. are given under Comparisons for the latter.

Remarks. Thrissina whiteheadi was described as Thryssa whiteheadi by Wongratana (1983) on the basis of specimens collected from Iraq and Iran. Subsequently, the species has been recorded from coasts and rivers flowing into the Persian Gulf (see synonym list). Some distributional records of T. whiteheadi are doubtful. Al-Jufaili et al. (2010) included T. whiteheadi in a list of fishes recorded from Oman, referring to Randall (1995). Although the latter suggested that T. whiteheadi was possibly distributed on the Oman coast, his color photograph for the species was of a Saudi Arabian specimen (BPBM 30365), also examined herein and reproduced in Fig. 1a. Randall (1995) noted that a color photograph purported to be of Thrissina mystax (Bloch and Schneider 1801) in Kuronuma and Abe (1986) (a report on the fishes of Oman), was T. whiteheadi, even though the description of specimens of T. mystax collected from Oman by Kuronuma and Abe (1986: p. 42) closely matched the diagnosis of T. mystax given subsequently by Whitehead et al. (1988) and Wongratana et al. (1999). In fact, the color photograph in question was the same figure as shown in Kuronuma and Abe (1972: fig. 2), having been taken of an individual collected from Sulaibikhat, Kuwait (western coast of Persian Gulf). To date, T. whiteheadi has not been positively identified from waters outside the Persian Gulf, and is, therefore, not considered to be distributed in Oman.


Thrissina supra sp. nov.


(New English name: Pakistan Thryssa)


(Fig. 3; Tables 1, 2, 3, 4)

Fig. 3
figure 3

a Holotype of Thrissina supra sp. nov., KAUM–I. 68985, 135.4 mm SL, Sindh, Pakistan; b–d paratype of T. supra, NSMT-P 138461, 88.4 mm SL, Sindh, Pakistan (lateral, dorsal, and ventral views, respectively)

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Holotype. KAUM–I. 68985, 135.4 mm SL, Sindh, Pakistan, trawl (collected at West Wharf, Karachi Port), coll. by H. B. Osmany.

Paratypes. 15 specimens, 55.5–88.4 mm SL, collection data as for holotype. KAUM–I. 68991, 81.1 mm SL, KAUM–I. 69303, 84.5 mm SL, KAUM–I. 69339, 56.0 mm SL, KAUM–I. 69343, 63.4 mm SL, KAUM–I. 69345, 66.4 mm SL, KAUM–I. 69349, 75.2 mm SL, KAUM–I. 69356, 78.9 mm SL, KAUM–I. 69359, 70.9 mm SL, KAUM–I. 69366, 74.4 mm SL, KAUM–I. 69368, 55.5 mm SL, KAUM–I. 69380, 80.5 mm SL, KAUM–I. 69384, 76.1 mm SL, KAUM–I. 69387, 66.7 mm SL, NSMT-P 138461, 88.4 mm SL, NSMT-P 138462, 74.5 mm SL.

Diagnosis. A species of Thrissina with the following combination of characters: upper jaw relatively long, its posterior tip slightly beyond opercle posterior margin, but not reaching the pectoral-fin insertion; first supramaxilla absent; teeth on both jaws robust, enlarged; dorsum with distinct paired dark lines in preserved specimens; dark blotch behind upper part of gill opening sometimes present in preserved specimens; dorsal fin with 10 or 11 (modally 10) branched rays; anal fin with usually 42–45 (rarely 40, modally 44) branched rays; pectoral fin with 11 or 12 (modally 11) branched rays; transverse scales 12 or 13 (12); scale rows in longitudinal series 45–47 (46); gill rakers 15–16 (15) in upper series on first gill arch, 20–23 (22) in lower series, 35–39 (37) in total; gill rakers 12–14 (modally 13) in upper series on second gill arch, 21–23 (22) in lower series, 33–37 (35) in total; gill rakers 10–11 (10) in upper series on third gill arch, 12–14 (13) in lower series, 22–24 (23) in total; gill rakers 7–9 (8) in upper series on fourth gill arch, 10–13 (11) in lower series, 18–22 (19) in total; snout long, 3.7–4.1% SL; pelvic fin long, 9.0–10.4% SL; mandible long, 17.3–18.3% SL; pelvic-fin insertion to anal-fin origin 17.0–18.8% SL.

Description. Data for holotype presented first, followed by paratype data in parentheses (if different). Body strongly compressed laterally, greatest depth at dorsal-fin origin. Dorsal profile of head and body gently elevated from snout tip to dorsal-fin origin, gradually lowering to uppermost point of caudal-fin base. Ventral profile of body dropping from mandibular tip to pelvic-fin insertion, gently rising to anal-fin base end, subsequently parallel to body axis to lowermost point of caudal-fin base. Abdomen covered by 15 (15 or 16) and 10 (9 or 10) sharp needle-like scutes from isthmus to pelvic scute, and pelvic scute to anus, respectively. Anus just anterior to anal-fin origin. Caudal peduncle compressed, its depth greater than orbit diameter. Pectoral-fin insertion slightly anterior to posterior tip of opercle. Uppermost ray of pectoral fin unbranched, other rays branched. Posterior tip of pectoral fin pointed, slightly beyond pelvic-fin insertion. Upper, lower, and posterior margins of pectoral fin nearly straight. Pelvic-fin insertion anterior to dorsal-fin origin. Posterior tip of depressed pelvic fin not reaching to anus. Anteriormost ray of pelvic fin unbranched, other rays branched. Dorsal-fin origin anterior to anus. Anterior three rays unbranched. Single spine-like scute located just anterior to dorsal-fin origin. Anal-fin origin just below origin of eighth (seventh to tenth) dorsal-fin ray. Lower contour of anal fin lowering from fin origin to fifth fin ray tip, almost parallel to ventral profile of body. Caudal fin forked. Head compressed. Snout length much less than orbit diameter. Snout tip rounded, at about horizontal level of upper margin of eye. Eye round, covered with adipose eyelid, lateral on head, dorsal to horizontal through pectoral-fin insertion, visible in dorsal and ventral views. Pupil round. Orbit elliptical. Nostrils close to each other, anterior to anterior margin of orbit and above horizontal through midline of body. Posterior margin of preopercle convex, smooth. Subopercle with rounded posterior margin. Opercular membrane without serrations. Pseudobranchial filaments present, covered with fleshy membrane. Interorbital space flat. Mouth large, inferior, below body axis, extending backward beyond posterior margin of eye. Mandible slender, much shorter than maxilla. Maxilla long, posterior tip pointed, slightly beyond posterior margin of opercle, but not reaching pectoral-fin base. First supramaxilla absent. Robust enlarged conical teeth in single row on both jaws. Single row of small conical teeth on palatine. Several conical teeth on vomer. Small conical teeth patch on pterygoid. Several rows of conical teeth on upper edges of basihyal and basibranchial. No teeth on dorsal surface of hyoid. Gill rakers long, slender. Each serra on gill rakers almost same size. Gill membrane on each side joined distally, most isthmus muscle exposed (not covered by gill membrane). Scales absent on head and fins. Lateral line absent. Scales cycloid, thin, deciduous.

Coloration of preserved specimens. Head and body almost uniformly pale brown. Lower lateral surface of body whitish-silver (lateral surface silver in some paratypes). Dark blotch behind upper part of gill opening (absent or indistinct in paratypes). Narrow black line running from upper part of gill opening to caudal-fin base. Holotype (largest specimen examined) with melanophores scattered on mandible (melanophores absent on mandible in all paratypes; Fig. 3). Dorsum dark brown. Distinct paired dark lines on dorsum from occiput to caudal-fin origin (Fig. 3c). All fins pale, semi-transparent. No melanophores on pectoral, pelvic, and anal fins. Melanophores scattered along caudal-fin rays and anterior part of dorsal fin. Coloration of fresh specimens unknown.

Distribution. Currently known only from the Sindh coast, Pakistan (Fig. 2). The type specimens were collected by trawl.

Etymology. The specific name “supra”, a Latin adverb, refers to the higher counts of scales, fin rays, and gill rakers in this species compared with related species.

Comparisons. The new species is assigned to the genus Thrissina, conforming to the definitions of Whitehead et al. (1988) and Wongratana et al. (1999) (as Thryssa) in having strongly keeled prepelvic and postpelvic scutes on the ventral edge, a spine-like scute on the dorsal-fin origin, dorsal and anal fins with 13 or 14, and 44–49 rays, respectively, the uppermost pectoral-fin ray not extended as a filament, and conical teeth on both jaws. Thrissina supra sp. nov. most closely resembles T. whiteheadi, both sharing a long maxilla, its posterior tip slightly beyond the posterior opercle margin, jaws with robust, enlarged teeth, lower gill rakers on the first gill arch numbering more than 17, abdominal scutes fewer than 27, and absence of the first supramaxilla (Roberts 1978; Wongratana 1983, 1987; Whitehead et al. 1988; Wongratana et al. 1999; Hata and Motomura 2019; Hata and Koeda 2020; Hata et al. 2020; this study).

Thrissina supra can be readily distinguished from T. whiteheadi by the presence of distinct paired dark lines on the dorsum (Fig. 3c) (vs. lines absent in T. whiteheadi; Fig. 1c); higher counts of longitudinal series scale rows (45–47 vs. 40–42; Table 3), transverse scales (12 or 13 vs. 10 or 11), total gill rakers on the first gill arch [35–39 vs. usually 30–34 (rarely 36); Fig. 4a], second gill arch [33–37 vs. usually 29–31 (rarely 34); Fig. 4b], third gill arch [22–24 vs. usually 19–21 (rarely 23); Fig. 4c], and fourth gill arch [18–22 vs. usually 14–18 (rarely 19); Fig. 4d], and branched anal-fin rays [42–45 (rarely 40) vs. 39–42 (43); Table 4]; a longer snout (3.7–4.1% SL vs. 3.1–3.6%; Fig. 5a), pelvic fin (9.0–10.4% SL vs. 7.7–9.0%; Fig 5b), and mandible (17.3–18.3% SL vs. 15.4–17.2%; Fig. 5c); and a shorter pelvic-fin insertion to anal-fin origin distance (17.0–18.8% SL vs. 19.1–24.2%; Fig. 5d).

Fig. 4
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Relationships of total gill raker numbers (TGR) on a first gill arch (1GA), b second gill arch (2GA), c third gill arch (3GA), and d fourth gill arch (4GA) to standard length in Thrissina whiteheadi (open triangles) and T. supra sp. nov. (closed circles)

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Fig. 5
figure 5

Relationships (as% SL) of a snout length, b pelvic-fin length, c mandibular length, and d distance from pelvic-fin insertion to anal-fin origin (P2–A) to SL in Thrissina whiteheadi (open triangles) and T. supra sp. nov. (closed circles)

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Comparative materials. Thrissina dayi: BMNH 1889.2.1.1803, holotype of Thryssa dayi, 202.7 mm SL, Mumbai, India; Thrissina gautamiensis: ZSI F 4600/2, holotype of Thryssa gautamiensis, 106.6 mm SL, Godavari Estuary, near Bhairavapalem, Andhra Pradesh, India.