Sardinella ventura, Hata & Motomura, 2021

Hata, Harutaka & Motomura, Hiroyuki, 2021, Sardinella ventura n. sp. (Actinopterygii: Clupeiformes: Clupeidae), a new sardine from Mauritius, Zootaxa 4975 (2), pp. 389-396 : 390-395

publication ID	https://doi.org/ 10.11646/zootaxa.4975.2.10
publication LSID	lsid:zoobank.org:pub:57894D1B-C5D5-445F-8432-CB74152C4074
DOI	https://doi.org/10.5281/zenodo.4925396
persistent identifier	https://treatment.plazi.org/id/03E63B2C-FFF9-747E-CF9E-FF13FB47DFCC
treatment provided by	Plazi
scientific name	Sardinella ventura
status	sp. nov.

Treatment

Sardinella ventura n. sp.

[New English name: Fortune Sardinella ]

( Figures 1–2 View FIGURE 1 View FIGURE 2 ; Tables 1–2 View TABLE 1 View TABLE 2 )

Holotype. BMNH 1982.8 .18.1, 95.3 mm SL, approx. 2.4 km (1.5 miles) north of Flic-en-Flac , Black River District, west coast of Mauritius, collected by J. De Baissac.

Paratypes. 9 specimens (93.8–102.6 mm SL): BMNH 1982.8.18.2–8 , 7 specimens, 94.1–102.6 mm SL, KAUM – I. 142159, 93.8 mm SL, NSMT-P 136594 , 98.4 mm SL, collected with the holotype.

Diagnosis. A species of Sardinella with the following combination of characters: caudal fin posteriorly margined black; black spot on dorsal-fin origin; lateral body scales with centrally discontinuous vertical striae and pores posteriorly; body scales non-deciduous; pelvic fin with 1 unbranched and 7 branched rays; dorsal fin with 4 or 5 unbranched rays; anal fin with 3 unbranched and 16–21 (modally 18) branched rays; gill rakers 54–63 (60) on upper limb of first gill arch, 94–110 (96) on lower limb, 150–168 in total; 17 or 18 (18) + 13 or 14 (14) = 30–32 (32) scutes on ventral edge of body; 41–43 (41) lateral scale rows in longitudinal series; 11 or 12 (12) transverse scales; pseudobranchial filaments 17–19 (17); head long, 27.9–30.0% SL; maxilla long, 12.0–13.0% SL; lower jaw long, 12.4–13.7% SL; caudal peduncle short, 6.2–7.6% SL; eye large, 8.4–9.9%; orbit large, 9.6–12.3%; pectoral fin long, 21.0–22.7%; pelvic fin long, 12.5–13.5%.

Description. Counts and measurements, expressed as percentages of SL, given in Table 1 View TABLE 1 . Data for holotype presented first, followed by paratype data in parentheses. Body oval, strongly compressed, deepest at dorsal-fin origin. Dorsal profile of body rising gently from snout tip to dorsal-fin origin, thereafter decreasing to uppermost point of caudal-fin base. Ventral profile of body lowering gently from lower-jaw tip to anteriormost point of pelvicfin insertion, thereafter elevated to lowermost point of caudal-fin base. Abdomen from isthmus to anus covered with 32 (30–32) keeled scutes. Predorsal scutes absent. Mouth terminal, small, posterior tip of maxilla just reaching (or slightly short of) a vertical through anterior margin of iris. Premaxilla and hypomaxilla lacking teeth. Ventral margin of maxilla toothed. Lower jaw with several conical teeth. Eye covered by adipose eyelid. Interorbital space flat. Nostrils close to each other, anterior to orbit. No lateral line. Pseudobranchial filaments present. Gill opening with two fleshy outgrowths on posterior margin, a large papilla on ventral margin. Posterior margins of preopercle and opercle smooth. Anteriormost point of pectoral-fin insertion anterior to posteriormost point of posterior margin of opercle. Posterior tip of pectoral fin pointed; dorsal, ventral, and posterior margins nearly linear. Dorsal-fin origin anterior to middle of body. Last dorsal-fin ray not filamentous.Anteriormost point of pelvic-fin insertion located just below 9th (7th–9th) dorsal-fin ray base. Depressed posterior tip of pelvic fin reaching between a vertical through posterior end of dorsal-fin base and anus. Anal-fin origin posterior to a vertical through posterior end of dorsal-fin base. Two posteriormost anal-fin rays enlarged. Caudal fin forked, posterior tips of both lobes pointed. Anus on ventral midline, just anterior to anal-fin origin, posterior to midpoint of body. Scales cycloid, thin, non-deciduous. Ventral scutes robust. Lateral scales on body with centrally discontinuous vertical striae and small pores posteriorly ( Fig. 2 View FIGURE 2 ). Bases of dorsal and anal fins with low scaly sheaths. Predorsal scales paired. No elongate, wing-like scales present beneath normal paired scales. Head and fins scaleless, except for broad triangular sheath of scales on caudal fin.

Color of preserved specimens. Body uniformly silver, dorsum to upper part of lateral surface of body light brown. Melanophores scattered on upper body scales (densely) and upper part of dorsal fin. Black spot on dorsalfin origin. Pectoral, pelvic, and anal fins uniformly pale yellow. Melanophores restricted to first pectoral-fin ray or (rarely) absent. Caudal fin posteriorly margined black. Melanophores scattered along caudal fin rays. Life and fresh coloration unknown.

Distribution. Currently known only from Mauritius.

Etymology. The specific name ventura is derived from Latin meaning “fortune”, reflecting the unexpected find of the type specimens in the BMNH specimen collection.

Remarks. The new species is assignable to the genus Sardinella , as defined by Whitehead (1985) and Munroe et al. (1999), due to having a compressed body, the abdomen covered with prominently keeled scutes, paired predorsal scales, a symmetrical second supramaxilla and toothless hypo-maxilla, the anal fin with two enlarged posteriormost rays and dorsal fin without filamentous rays, and two fleshy outgrowths on the hind margin of the gill opening. It is readily distinguished from all other congeners, except S. dayi , by having eight pelvic fin-rays (total), scales with centrally discontinuous vertical striae and small pores posteriorly, more than 87 gill rakers on the first gill arch lower limb, and a black spot on the dorsal-fin origin ( Whitehead 1985; Munroe et al. 1999; Stern et al. 2016; Hata & Motomura 2019a –d).

However, S. ventura n. sp. can be easily distinguished from S. dayi by having greater numbers of lateral scale rows in the longitudinal series [41–43 (modally 41) vs. 38–42 (40) in S. dayi ], transverse scales [11 or 12 (12) vs. 11], and pseudobranchial filaments [17–19 (17) vs. 18–22 (19)] ( Table 1 View TABLE 1 ; Fig. 3A View FIGURE 3 ), a shorter caudal peduncle [6.2–7.6% SL (mean 7.0%) vs. 8.2–12.0% (9.2%)], larger eye [8.4–9.9% (9.0%) vs. 6.8–8.0% (7.4%)] and orbit [9.6–12.3% (10.7%) vs. 8.5–10.2% (9.3%)], longer pectoral [21.0–22.7% (21.5%) vs. 17.8–21.0% (19.8%)] and pelvic fins [12.5–13.5% (12.8%) vs. 10.4–12.2% (11.2%)] ( Table 2 View TABLE 2 ; Fig.3 View FIGURE 3 ).

Moreover, Welch’s T-test for comparison of meristic characters between the two species showed that significant differences (p <0.01) between the two were found in unbranched dorsal-fin rays, branched anal-fin rays, upper, lower, and total gill rakers on the first gill arch, scale rows in the longitudinal series, transverse scales, and pseudobranchial filaments. P values of the numbers of unbranched dorsal-fin rays and lower gill rakers were 0.023 and 0.023 respectively, and no significant differences were found in other meristics. In addition, ANCOVA analysis of 23 morphometrics showed that significant differences (p <0.05) were observed in 14 characters (lengths of head, pre-dorsal-fin distance, distance between snout and pectoral-fin insertion, distance between snout and analfin origin, anal-fin base, caudal peduncle, snout, pectoral fin, pelvic fin, maxilla, mandible, and postorbital area, diameters of orbit and eye, and caudal-peduncle depth) between the two species.

Two congeners, S. jussieui ( Hata & Motomura 2019d: fig. 1) and S. melanura ( Fig. 4 View FIGURE 4 ), co-occur with S. ventura in Mauritius. Sardinella ventura clearly differs from S. jussieui in having body scales with pores posteriorly (vs. no pores on scales in S. jussieui ), higher counts of total gill rakers on the first gill arch (150–168 in S. ventura vs. 137–155), and a longer head (27.9–30.0% SL vs. 23.2–24.9%), maxilla (12.0–13.0% SL vs. 9.6–10.7%), and mandible (10.3–11.7% SL vs. 12.4–13.7%) ( Hata & Motomura 2019d; this study). Sardinella ventura also differs from S. melanura in having the caudal fin with an indistinct dark posterior margin (vs. caudal fin with distinct black blotches on both tips in S. melanura ; Fig. 4 View FIGURE 4 ), a black spot on the dorsal-fin origin (vs. spot absent) ( Whitehead 1985; Munroe et al. 1999), the body scales with pores posteriorly (vs. scale pores absent), and higher counts of lower gill rakers on the first gill arch (94–110 vs. 38–74 in S. melanura ) ( Whitehead 1985; Munroe et al. 1999; Hata et al. 2016).

Comparative material examined. Sardinella dayi (34 specimens, 86.5–120.9 mm SL): listed in Hata & Motomura (2019d) and seven additional specimens: BMNH 1970.4.24.1, 91.9 mm SL, Palaly, Jaffa, Sri Lanka; BMNH 1982.9.6.93–97, 5 specimens, 112.9–120.5 mm SL, Phuket, Thailand; CAS-SU 41420, 114.8 mm SL, Goa, India. Sardinella jussieui (13 specimens, 94.8–141.7 mm SL): listed in Hata and Motomura (2019d). Sardinella melanura: KAUM ‒I. 60839, 96.4 mm SL, Tudumari Beach, Iriomote Island, Ryukyu Islands, Japan.