Pseudoambassis elongatus 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 : 568

Pseudoambassis elongatus Castelnau [= Ambassis elongatus ]

Figure 3

Pseudoambassis elongatus Castelnau 1878b: 44 (type locality, Norman River ).

Castelnau (1878b) described Pseudoambassis elongatus from “several specimens not much over an inch long” (p. 44) from the Norman River. Macleay (1881) simply listed the species in his catalogue of Australian fishes. McCulloch (1929b) regarded it as a valid species of Ambassis , but did not mention whether he had seen the syntypes. Whitley (1935) noted that there were two small syntypes in the Macleay Museum, the larger of which he designated lectotype. He illustrated the lectotype as well as the dorsal and anal fins of the paralectotype (Whitley 1935:fig. 6), and considered them to be juveniles of Austrochanda macleayi (Castelnau) . Allen & Burgess (1990) considered P. elongatus to be a valid species of Ambassis , but noted (p. 163): “Apparently the type specimen is lost. It is not among the collections of AMS or MNHN.” Allen et al. (2006) also regarded P. elongatus as a valid species of Ambassis , and listed MAMU as the repository for the lectotype and paralectotype, but did not examine either specimen.

There are two specimens in the Macleay Museum (MAMU F.431), which agree well with Whitley’s illustrations of the lectotype and paralectotype. The old external label for the specimens says “ PSEUDOAMBASSIS ELONGATUS , Casteln. NORMAN RIVER”; an internal card in the jar repeats the same information. The index card for the specimens says “ Pseudoambassis elongatus, Cast. […] 2 sp. 1″ Norman River”. As with the P. macleayi types, Jenny Anderson’s entry in the catalogue of the Macleay Museum fish collection mistakenly lists the specimens only as ‘topotypes’. They too were not listed in Stanbury’s (1969) type catalogue, and accordingly were excluded from the 1970 transfer of fish types to the AMS.

The specimens are in very poor condition. The larger of the two (the lectotype) is in particularly poor condition, with the head bent to the left and partially disarticulated from the body ( Figure 3 ). The lectotype measures approximately 29 mm SL, and the paralectotype 22.5 mm SL. Details discernible from the specimens are as follows: single supraorbital spine; nasal spine absent; two transverse scale rows on cheek; dorsal and anal fins each with seven segmented rays; lateral line incomplete; predorsal scales nine; vertical scale rows from upper edge of gill opening to caudal-fin base 25; horizontal scale rows from anal-fin origin to dorsal-fin base 11. This combination of characters is unique among Australian ambassids ( Allen & Burgess 1990), and we regard the two MAMU specimens in F431 as the lectotype and paraalectotype of Ambassis elongatus .

Figures

FIGURE 3. Pseudoambassis elongatus Castlenau, lectotype, MAMU F.431, ca 29 mm SL. Photo by Y.K. Tea.