Engraulis nasutus Castelnau 1878

Gill, Anthony C., Russell, Barry C. & Nelson, Gary, 2018, F. L. de Castelnau’s Norman River fishes housed in the Macleay Museum, University of Sydney, Zootaxa 4459 (3), pp. 565-574 : 571-572

Engraulis nasutus Castelnau 1878 [= Thryssa nasuta ]

Figures 6–7

Engraulis nasutus Castelnau 1878b: 51 (type locality, Norman River ).

Castelnau (1878b) described Engraulis nasutus on the basis of an unspecified number of specimens from the Norman River. He noted that “I have seen only one adult specimen seven inches long, but I have a small specimen preserved in spirits, which is silvery with the upper parts of a light brown, fins yellow”. This suggests he had at least two specimens.

Identification of the species has been problematic. Macleay (1879) considered it to be a valid species of Engraulis , stating (p. 367): “This species is described by Count Castelnau […] from one adult specimen, 7 inches long, sent to him from the Norman River, Gulf of Carpentaria. Its special distinguishing character seems to be a strong longitudinal ridge along the top of the head.” Macleay’s mention of a single specimen is curious, given that there are two specimens in MAMU (see below). Ogilby (1910) considered E. nasutus to be a valid species of Anchovia Jordan & Evermann in Jordan (1895), and compared it with his new species A. aesturia . It is unlikely that Ogilby saw type material of E. nasutus , as all of his comparative data for the species is identical to that in Castelnau’s original description. McCulloch (1929a) regarded E. nasutus as a valid species of Anchoviella Fowler (1911) , but did not indicate whether he had examined the syntypes. Whitley (1964) considered both E. nasutus and A. aestuaria to be valid species of Thrissina Jordan & Seale (1925). Whitehead et al. (1988) tentatively placed E. nasutus in the synonymy of Thryssa hamiltoni ( Gray 1835) , which was followed also by Wongratana et al. (1999). Paxton et al. (2006) listed it as incertae sedis in the Engraulidae , and as a possible synonym of Thryssa hamiltoni . They noted (p. 317): “ syntypes whereabouts unknown.”

There are two specimens in the Macleay Museum ( MAMU F.1194; Figures 6–7 ), measuring 99.5 and 104.5 mm SL (TL not determinable owing to caudal-fin damage). They correspond to an index card stating “ Engraulis nasutus, Cast. […] 2 sp. 6″ Norman R., N. Australia ”. The specimens have the following characters (where two counts are presented, the first is from the 99.5 mm SL specimen): predorsal scutes 1; abdominal scutes sharply keeled, 14 prepelvic + 9 postpelvic = 23 total; maxilla relatively short, reaching to posterior border of preopercle; anal-fin rays 34 (iv,30; anterior ray tips damaged in 104.5 mm SL specimen); total dorsal-fin rays 13; uppermost pectoral-fin ray not filamentous; teeth in jaws fine and conical, not canine-like; lower gill rakers 25 (checked in 104.5 mm SL specimen only). This combination of characters is unique among engraulids to the species currently called Thryssa aestuaria ( Ogilby 1910) . According to Paxton et al. (2006), there are three other species of Thryssa known from the Gulf of Carpentaria: T. hamiltoni , T. scratchleyi ( Ramsay & Ogilby 1886) and T. setirostris ( Broussonet 1782) . The MAMU specimens differ from T. hamiltoni in having fewer prepelvic scutes (14 vs 15–20) and more lower gill rakers (25 vs 11–15); from T. scratchleyi in having fewer abdominal scutes (14 prepelvic + 9 postpelvic vs 19 + 12) and more lower gill rakers (18–23 in T. scratchleyi ); and from T. setirostris in having a much shorter maxilla (reaching to preopercle edge vs to at least tip of pectoral fins), fewer abdominal scutes (16–18 + 9– 10 = 25–28 in T. setirostris ) and more lower gill rakers (10–12 in T. setirostris ).

We regard the specimens in MAMU F.1194 as syntypes of Engraulis nasutus Castelnau, 1878 , and identical to Anchovia aestuaria Ogilby, 1910 . Engraulis nasutus thus is a subjective senior synonym of A. aestuaria . We here follow Eschmeyer et al. (2018, and references therein) in recognising Thryssa Cuvier (1829) rather than Thrissina Jordan & Seale (1925) ( Kottelat 2013) as the correct generic name for Thryssa nasutus .

Pusey et al. (2017) recorded only a single engraulid from freshwaters of northern Australia, Thryssa scratchleyi . Thryssa nasuta is known only from estuarine and marine areas (Whitehead et al. 1988, Wongratana et al. 1999); presumably the syntypes of E. nasutus were collected from the lower, estuarine reaches of the Norman River.

Figures

FIGURE 6. Engraulis nasutus Castlenau, syntypes, MAMU F.1194, 99.5 (upper) and 104.5 (lower) mm SL. Photo by Y.K. Tea.

FIGURE 7. Engraulis nasutus Castlenau, syntypes, MAMU F.1194, 99.5 (upper) and 104.5 (lower) mm SL. Radiograph by J. King.