Thrissina evermanni

Hata, Harutaka, Mandagi, Ixchel F. & Masengi, Kawilarang W. A., 2023, Resurrection of nominal species previously regarded as junior synonyms of Thrissina baelama (Fabricius, 1775) and their re-descriptions (Teleostei: Clupeiformes: Engraulidae), Raffles Bulletin of Zoology 71, pp. 279-302 : 286-288

Thrissina evermanni ( Jordan & Seale, 1906)

[English name: Evermann’s Baelama Anchovy ] ( Fig. 5 ; Tables 4, 8)

Anchovia evermanni Jordan & Seale, 1906: 188, fig. 4 (type locality Apia, Upolu Island , Samoa).

Thryssa baelama (not of Fabricius): Whitehead et al., 1988 (in part): 425 ( Fiji to Tonga); Wongratana et al., 1999 (in part): 1743 ( Fiji to Tonga).

Holotype. USNM 51719 , 105.0 mm SL, Apia , Samoa, 1902, D. S. Jordan and V. L. Kellogg.

Paratypes. 4 specimens, 84.5–98.3 mm SL: CAS-SU 8730 , 3 specimens 84.5–98.0 mm SL, Apia , Samoa; USNM 451580 , 98.3 mm SL, collected with the holotype.

Other material examined. 4 specimens, 53.7–87.3 mm SL: BMNH 1971.8.25.112–114 , 3 specimens, 53.7–62.8 mm SL, Fiji; BPBM 41796 , 87.3 mm SL, Tonga .

Diagnosis. A species of Thrissina with the following combination of characters: short maxilla, its posterior tip not reaching to posterior margin of opercle; first supramaxilla elongated, longer than half length of second; abdomen covered with 4–6 + 8–10 = 12–16 keeled scutes; no scutes anterior to pectoral fin; 1UGR 16–18, 1LGR 21–23, 1TGR 38–40; 2UGR 13–15, 2LGR 22–24, 2TGR 36–38; 3UGR 11–12, 3LGR 13–15, 3TGR 25–27; 4UGR 10–11, 4LGR 10–12, 4TGR 20–23; no distinct black blotches on dorsal fin; caudal peduncle narrow [9.3–10.2% (mean 9.7%) of SL] and long (9.7–10.5% of SL); pre-dorsal-fin long, 50.6–52.0% of SL; snout long, 4.9–5.3% of SL.

Colour of preserved specimens. Body uniformly silver, sometimes pale. Dorsum dark brown. Upper lateral surface of body light brown. Melanophores densely scattered over entire body and head. Narrow non-pigmented ring-like band surrounding anterior part of snout. Melanophores scattered along dorsal- and caudal-fin rays. Pectoral, pelvic, and anal fins without melanophores. No distinct black blotches on dorsal fin.

Distribution. Currently known from Fiji, Tonga, and Samoa ( Fig. 4 ).

Comparisons. Thrissina evermanni (1TGR 38–40) is diagnosed by a gill raker range intermediate between those of T. samam (1TGR <37) and T. polynemoides (1TGR> 39), and T. tuberculosa (1TGR> 40) ( Fig. 6 ). Thrissina evermanni can be distinguished from T. baelama (1TGR 36–40), with which it shares very similar gill raker numbers, by the narrower caudal peduncle (9.3–10.2% of SL vs. 10.1–11.5%)], and longer pre-dorsal-fin (50.6–52.0% of SL vs. 48.0–50.4%) and snout (4.9–5.3% of SL vs. 3.9–4.8%). The long snout of T. evermanni also differentiates that species from T. polynemoides (snout length: 4.7–4.9% of SL) and T. tuberculosa (4.7–5.0%) ( Fig. 7 ). Moreover, T. evermanni has a narrower caudal peduncle than T. polynemoides (9.3–10.2% of SL in T. evermanni vs. 9.9–10.6% in T. polynemoides ). Additionally, T. evermanni differs from T. tuberculosa by lacking black blotches anteriorly on the dorsal fin (vs. several distinct black blotches present in T. tuberculosa ).

Remarks. Thrissina evermanni was originally described as Anchovia evermanni by Jordan and Seale (1906), based on five specimens collected from Apia, Upolu Island, Samoa. Although the original description designated a single specimen (USNM 51719) as the holotype, that lot included two specimens ( Fricke et al., 2022), one (105.0 mm SL, 127.7 mm TL; 1LGR 23) being untagged and the other (98.3 mm SL; 1LGR 22) with two metal tags. The former matched the original description in both specimen size [five inches in total length (ca. 12.7 cm)] and gill raker number (23 gill rakers on lower gill limb of first gill arch), and is here considered to be the holotype of the nominal species. The smaller specimen is now reregistered as USNM 451580.

Figures

Fig. 5. A, Holotype of Anchovia evermanni, USNM 51719, 105.0 mm, and B, paratype of Anchovia evermanni, USNM 451580, 98.3 mm SL, Apia, Samoa.

Fig. 4. Distributional records of Thrissina baelama (triangles), T. evermanni (squares), T. polynemoides (diamonds), T. samam (circles), and T. tuberculosa (star), based on specimens examined in this study.

Fig. 6. 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 baelama (blue triangles ▲), T. evermanni (yellow squares ■), T. polynemoides (green diamonds ◆), T. samam (red circles ●), and T. tuberculosa (pink stars).

Fig. 7. Morphometrics of Thrissina baelama (blue triangles ▲), T. evermanni (yellow squares ■), T. polynemoides (green diamonds ◆), T. samam (red circles ●), and T. tuberculosa (pink stars) (all vs. standard length; SL). A, Ratio of caudal-peduncle depth to SL; B, pre-dorsal-fin length to SL; C, snout length to SL, D, body depth to SL; E, pre-anal-fin length to SL; F, dorsal-fin base length to SL; G, distance from pelvic-fin insertion to anal-fin origin to SL; H, pectoral-fin length to SL; I, pelvic-fin length to SL; J, maxilla length to SL; K, lower-jaw length to SL; L, caudal-peduncle length to SL.