Eleotridae Bleeker, 1877

Schwarzhans, Werner, Scofield, R. Paul, Tennyson, Alan J. D., Worthy, Jennifer P. & Worthy, Trevor H., 2012, Fish remains, mostly otoliths, from the non-marine early Miocene of Otago, New Zealand, Acta Palaeontologica Polonica 57 (2), pp. 319-350 : 334

Family Eleotridae Bleeker, 1877

Several fossil fish skeletons have been reported ( McDowall et al. 2006b; McDowall 2009, 2010) as unidentified species of the eleotrid genus Gobiomorphus from the Bannockburn Formation from Fiddlers Flat (equals the Manuherikia River

Section, fossil record number H41/f66; Fig. 2 ) and Vinegar Hill, in beds close to those from which the otoliths described below derive, and from Pleistocene sediments of Gisborne.

Otoliths of Recent eleotrid species have rarely been figured in the literature. We have therefore figured an appropriate selection of otoliths from Recent species from the Indo West−Pacific for comparison purposes ( Figs. 11, 12 ). Otoliths of the Gobioidei , including those of Eleotridae , are easily recognized by the “shoe−sole−shaped” sulcus with an undivided colliculum located somewhat inclined on the centre of the inner face and not opening anteriorly. The otolith shape is more or less rectangular; the inner face is flat to slightly convex, with a distinct ventral line and usually a distinct dorsal depression.

Generally, eleotrid otoliths do not differ greatly from those of other gobioid families, particularly the Gobiidae , although most otoliths of eleotrids lack the postdorsal projection seen in many gobiids, and they often show a postventral projection that is very rarely observed in gobiids (see also Reichenbacher and Weidmann 1992; Schwarzhans 2010).

Certain groups of distinct otolith morphologies can be observed in the Recent Eleotridae from the Indo West−Pacific, as follows.

(i) A group containing the genera Butis , Bostrychus , and Ophiocara ( Fig. 11A–I), all of the subfamily Butinae , are characterized by a trapezoidal outline with pronounced preventral and postventral projections. Another character of the otoliths of these genera is the location of the sulcus, which reaches close to the anterior−ventral rim of the otolith and sometimes almost opens to it. This character is interpreted as plesiomorphic.

(ii) The otoliths of the genera Gobiomorphus and Philypnodon ( Fig. 11K–S) of the subfamily Eleotrinae are largely similar to the above group in outline, but the sulcus stays at the centre of the inner face and does not approach the anterior rim. This group is endemic to Australia and New Zealand. Another endemic cave eleotrid from NW−Australia ( Milyeringa ) could belong to the same group ( Fig. 12P ).

(iii) Another group comprises mostly genera from the subfamily Eleotrinae including Belobranchus , Bunaka , Giurus , Mogurnda , Allomogurnda , and Hypseleotris ( Fig. 12A–I ) and possibly also Calumia ( Fig. 11 J). These all have compressed otoliths with a ratio OL:OH ranging from 0.8 to 1.1, which is the main difference from the otoliths of group 2 (versus ratio OL:OH 1.2–1.4).

(iv) Finally, a fourth group of eleotrid genera includes Eleotris , Culius , and Oxyeleotris ( Fig. 12J–O ) that is characterized by more elongate otoliths, typically with a postdorsal instead of a postventral projection. Their otoliths do not show any significant distinction from many gobiid genera.

The eleotrid otoliths described here from the new extinct genus Mataichthys resemble most those of the genera Gobiomorphus and Philypnodon , which together with the endemic Grahamichthys (otoliths not known) represent the extant fresh water eleotrids in New Zealand and temperate Australia.

Figures

Fig. 2. Stratigraphic section showing the basal part of the Bannockburn Formation at the Manuherikia River location, New Zealand. FRN, Fossil Record Number in the archival Fossil Record File of the Geological Society of New Zealand.

Fig. 12. Otoliths of recent eleotrid fishes from the Indo West−Pacific for comparison. A. Allomogurnda nesolepis (Weber, 1907), Recent, 04°11’S– 144°46’E, WAM 29605−008, inner face. B. Belobranchus belobranchus (Valenciennes, 1837), Recent, 10°16’S–150°43’E, WAM 31634−005, inner face (B1), ventral view (B2). C. Bunaka gyrinoides (Bleeker, 1853), Recent, Ponape, collection W. Schwarzhans, donated by ZMH, inner face. D. Giurus margaritaceus (Valenciennes, 1837), Recent, 03°16’S–138°41’E, WAM 31753−002, inner face (D), ventral view (D). E. Giurus hoedti (Bleeker, 1854), 1 2 Recent, 01°51’S–136°33’E, WAM 31041−003, inner face. F. Mogurnda aurofodinae Whitley, 1938, Recent, 03°34’S–142°57’E, WAM 29838−001, inner face (F), ventral view (F). G. Mogurnda mogurnda (Richardson, 1844), Recent, northern Australia, collection W. Schwarzhans, donated by WAM, inner +