Milyeringa Whitley, 1945

Larson, Helen K., Foster, Ralph, Humphreys, William F. & Stevens, Mark I., 2013, A new species of the blind cave gudgeon Milyeringa (Pisces: Gobioidei, Eleotridae) from Barrow Island, Western Australia, with a redescription of M. veritas Whitley, Zootaxa 3616 (2), pp. 135-150 : 139-140

Milyeringa Whitley, 1945

Diagnosis. An eyeless eleotrid with first dorsal fin reduced (spines II–IV) to absent, segmented second dorsal fin rays 6–8 with no spine present; anal fin rays I,6–8 or 6–7; pectoral fin rays 11–13, all unbranched; pelvic fin rays I,3–4, all unbranched; segmented caudal fin rays 13–17, all unbranched and central rays sometimes elongate and filamentous; body scales cycloid, covering body in one species and almost absent in another; sensory canals and pores on head (and body) completely absent; sensory papillae on head in longitudinal pattern and on body in reduced vertical rows, papillae with very thin pointed flaps present (easily lost); head moderately long, becoming wide and depressed in large specimens; body fairly slender, compressed; jaws with few rows of small pointed teeth; body pigment absent but for few scattered fine brownish melanophores on top of head, fin membranes transparent to pale translucent whitish; vertebrae 7–10+13–15 (20–25 in total), 1–2 pre-anal pterygiophores, one epural; last haemal spine usually split or forked (with thin sheet of bone joining forks). Known so far only from caves and wells in the Cape Range peninsula and Barrow Island, Western Australia.

Molecular genetic data. The recovered COI gene tree is shown in Fig. 3 . The tree indicates a clear dichotomy within the genus as presently defined, with the Barrow Island Milyeringa CO1 sequence differing from that of mainland Milyeringa by 20%. This is equivalent to the divergence of each from Typhleotris , only slightly less than that from the odontobutid outgroup taxa, providing evidence of two very different species and strongly implying that the split between the two Western Australian species is ancient. Our unpublished preliminary molecular data indicate that this split is indeed ancient, which may have systematic implications. We are investigating this further, in light of Chakrabarty et al. (2012), who proposed that Milyeringa and the Madagascar cave gudgeon Typhleotris are sister-lineages.

It is not possible to assess the level of genetic variation within M. justitia n. sp. on Barrow Island at present, given the very limited sampling. A second individual from Anode well Q4 had an identical COI haplotype: however, additional sampling and analysis may yet reveal diversity and population sub-structuring within a very restricted region, as for M. veritas . Further assessment of the intraspecific variation is crucial, for clarification of the conservation status and management of this Barrow Island endemic.

Figures

FIGURE 3. Milyeringa COI neighbor-joining tree. Collection localities of samples are in parentheses following the sample number. Red indicates the M. brooksi haplotype clade and blue indicates those individuals collected from Kudumurra Well (C- 25).