Schindleria, Giltay, 1934

Ahnelt, Harald & Sauberer, Michael, 2020, Deep-water, offshore, and new records of Schindler’s fishes, Schindleria (Teleostei, Gobiidae), from the Indo-west Pacific collected during the Dana-Expedition, 1928 - 1930, Zootaxa 4731 (4), pp. 451-470 : 452-453

Classification of Schindleria

In the classification of Schindleriidae as a junior synonym of Gobiidae we follow Thacker (2009), a view adopted by several authors ( Gill & Mooi 2010; Betancur-R et al. 2017).

Six nominal species of Schindler’s fishes are documented, four from the Pacific and two from the Indian Ocean (Red Sea) ( Ahnelt & Sauberer 2018). But the number of species is obviously underestimated. Kon et al. (2007, 2011) found more than 30 cryptic species just in the western Pacific. Separation of these extremely paedomorphic species based on morphological characters is challenging ( Kon et al. 2007; Ahnelt & Sauberer 2018; Ahnelt 2019). The most striking difference between the first described species of Schindleria , S. praematura ( Schindler 1930) and S. pietschmanni ( Schindler 1931) , was the relative positions of the dorsal and anal fins: in S. praematura the origin of the dorsal fin is well in advance of the origin of the anal fin, while in S. pietschmanni the origin of the dorsal fin is just above the origin of the anal fin ( Schindler 1930; 1931; Johnson & Brothers 1993). Subsequently most authors followed this character and consequently named specimens from their samples either S. praematura or S. pietschmanni depending on the relative fin position.

We checked 49 publications (72 records) which reported findings of Schindler’s fishes ( Table 1 ). Excluding those publications which formally described a species (n = 6), the remaining 43 studies comprised 65 records of Schindleria . In 41 of these records the specimens were identified as S. praematura , in 14 as S. pietschmanni and in two as S. brevipinguis . Eight of the records were not assigned to a species and were identified as Schindleria sp. or Schindleriidae . In the light of high endemism and a large number of cryptic species ( Kon et al. 2007, 2011; Bogorodsky & Randall 2019) it is unlikely that all these documented records of Schindler’s fishes belong to one of these two species. Randall (2007) concluded that S. praematura and S. pietschmanni are endemic for the Hawaiian Islands.

It will require a series of integrative studies including ecology, genetics and morphology just to get an overview of the number of species of Schindleria , which possibly number several dozen. Species with very distinct morphological characters like S. brevipinguis (tiny and toothless) or S. macrodentata (relatively large, with few, but large teeth, last procurrent spine with extra spiny process) may be formally distinguished and may well prove to be valid species. Therefore, we preliminarily attribute all published records ( Table 1 ), including those of the Dana-Expedition, to two morphotypes (see below).