Eleotris

Dusky sleeper Eleotris fusca, copyright Wibowo Djatmiko.

Belongs within: Eleotridae.

Eleotris is a tropical genus of sleepers bearing a concealed spine at the preopercle angle (Smith 1958).

Sleepers
Published 16 June 2014
Hawaiian sleeper Eleotris sandwicensis, from the Hawaii Biological Survey.

Fishes of the genus Eleotris are a group of gobioids commonly known as the spinycheek sleepers. I haven’t found a definite statement as to why they’re called sleepers, but presumably it’s because, as sit-and-wait ambush predators, they spend a lot of time lying around on the bottom. Eleotris species are found in tropical and subtropical waters around the world, mostly in estuaries and freshwater. They are smallish fish, with most species seeming to be in the ten to twenty centimetre size range. The ‘spinycheek’ part of the vernacular name refers to the presence of a hook-like spine on the lower corner of the preoperculum (the bone running between the cheek and the gill cover on the side of the head). This spine may be covered with tissue and so not always readily visible, but Pusey et al. (2004) note that it ‘can be easily detected by running a thumbnail lightly, and carefully, along the preoperculum margin’. Carefully, I think, is the operative word here.

Eleotris oxycephala, from Chinese Academy of Fishery Sciences.

The species of Eleotris are mostly a conservative bunch appearance-wise, and the genus seems to have gotten a reputation for being difficult to work with taxonomically (it doesn’t help matters that for a long time ‘Eleotris‘ was something of a dumping ground for generalised gobioids). The Japanese species were revised in 1967 by Akihito (yes, that Akihito), the West African species have been revised by Miller (1998), and the North and South American species by Pezold & Cage (2002), but species from the remainder of the Indo-Pacific remain unrevised. There has been some disagreement over the status of a group of New World species classified in the genus Erotelis, which resemble Eleotris species but are generally more elongate and have higher numbers of fin rays (Pezold & Cage 2002). Miller (1998) felt that this genus should be synonymised with Eleotris, but Pezold & Cage (2002) argued that its members were distinct enough to be kept separate. A molecular phylogenetic analysis of the gobioids by Thacker & Hardman (2005) suggested that ‘Erotelis‘ is nested within Eleotris, which may support their synonymisation.

Dusky sleeper Eleotris fusca, photographed by C. Appleby.

The sleepers are amphidromous, meaning they spend part of their life in the sea. Sleepers enter the sea as larvae, returning to fresher waters as they mature. As a result of this marine stage in the life cycle, individual species of Eleotris may be widespread and can often be found in places such as oceanic islands that lack populations of permanently freshwater species. It has even been suggested they may cross oceans: Miller (1998), noting similarities between species on either side of the Atlantic, suggested that this may be the result of trans-Atlantic dispersal. Among the evidence cited in favour of this possibility was the record in 1987 of a specimen of the northern South American species Eleotris pisonis from the island of St Helena in the mid-Atlantic. However, Miller also noted that the amount of time it would take to disperse across the Atlantic is greater that the time it would take for the larva to develop to maturity (and mature Eleotris are not known from the open sea). Pezold and Cage (2002) were more skeptical about the possibility of trans-Atlantic dispersal, even though they admitted to being unable to identify any characters distinguishing the Caribbean E. amblyopsis from the West African E. daganensis. They queried whether the St Helena record may have been an individual transported in ship ballast water, rather than an unaided dispersal.

Systematics of Eleotris

Characters (from Smith 1958): Robust body covered with small scales, anteriorly cycloid, hinder ctenoid. Head depressed, scaly, except muzzle. Downwardly curved spine at preopercle angle. Gill openings lateral only. Teeth in bands, outer enlarged, no canines. V I 5.

<==Eleotris Bloch & Schneider 1801T09 (see below for synonymy)
    |--+--E. pictaT09
    |  `--E. pisonisT09
    `--+--+--E. amblyopsisT09
       |  `--E. fusca (Bloch & Schneider 1801)T09, S58 (see below for synonymy)
       `--+--+--E. acanthopomaT09
          |  `--E. sandwichensisT09
          `--ErotelisT09
               |--E. armigerT09
               `--E. smaragdusT09
Eleotris incertae sedis:
  *E. gyrinus Valenciennes 1837S58
  E. adspersa Castelnau 1878 [incl. E. mimus De Vis 1884]O97
  E. aquadulcis Allen & Coates 1990AC90
  E. castelnaui Macleay 1881 [incl. E. obscura Castelnau 1874 non Schlegel 1847]O97
  E. concolor De Vis 1884O97
  E. devisi Ogilby 1897 [=E. cavifrons De Vis 1884 non Day 1878]O97
  E. elongata Alleyne & Macleay 1877O97
  E. gobioides Valenciennes 1837S58 [=Gobiomorphus gobioidesO97]
  E. humilis De Vis 1884O97
  E. immaculata Macleay 1883O97
  E. larapintae Zietz 1896O97
  E. laticeps De Vis 1884O97
  E. legendrei Pellegrin 1919S58
  E. longicauda De Vis 1884O97
  E. macrodon Bleeker 1863O97
  E. macrolepis (Bleeker 1875)S58 [=Culius macrolepisM58; incl. E. guttatissimus Bliss in Gudger 1929 (n. n.)S58]
  E. melanosoma Bleeker 1852AC90 [=E. (Culius) melanosomaM58; incl. E. macrocephalus Weber 1913M58]
  E. melbournensis Sauvage 1880O97
  E. modesta Castelnau 1874O97
  E. nigrifilis Ogilby 1897 [=E. lineata Castelnau 1875 non Dormitator lineatus Gill 1863]O97
  E. oxycephala Schlegel 1850O97
  E. pallida Castelnau 1875O97
  E. planiceps Castelnau 1878O97
  E. reticulatus Klunzinger 1880O97
  E. robustusO97
  E. selheimi Macleay 1884 [incl. E. planiceps Macleay 1882 non Castelnau 1878]O97
  E. senegalensisEA03
  E. simplex Castelnau 1878O97
  E. sulcaticollis Castelnau 1878O97
  E. taeniura Macleay 1881O97
  E. tohizonae Steindachner 1880 [incl. E. pectoralis Regan 1903]S58
  E. vittata Dumeril 1860S58

Eleotris Bloch & Schneider 1801T09 [incl. Culius Bleeker 1856S58, Epiphthalmus Rafinesque 1815S58, Gobiomoroides Lacepede 1800S58]

Eleotris fusca (Bloch & Schneider 1801)T09, S58 [=Poecilia fuscaM58, Culius fuscusH27, Eleotris (Culius) fuscaM58, Cobitis pacifica Forster in Bloch & Schneider 1801 (n. n.)H27; incl. E. cavifrons Day 1878S58, E. fornasini Bianconi 1858S58, E. klunzingeri Pfeffer 1893S58, E. mauritianus Bennett 1831S58, E. nigra Quoy & Gaimard 1824S58, E. soaresi Playfair 1866S58]

*Type species of generic name indicated

References

[AC90] Allen, G. R., & D. Coates. 1990. An ichthyological survey of the Sepik River, Papua New Guinea. Records of the Western Australian Museum Supplement 34: 31–116.

[EA03] Écoutin, J.-M., & J.-J. Albaret. 2003. Relation longueur-poids pour 52 espèces de poissons des estuaires et lagunes de l’Afrique de l’Ouest. Cybium 27 (1): 3–9.

[H27] Herre, A. W. 1927. Gobies of the Philippines and the China Sea. Bureau of Printing: Manila.

Miller, P. J. 1998. The West African species of Eleotris and their systematic affinities (Teleostei: Gobioidei). Journal of Natural History 32 (2): 273–296.

[M58] Munro, I. S. R. 1958. The fishes of the New Guinea region: a check-list of the fishes of New Guinea incorporating records of species collected by the Fisheries Survey Vessel “Fairwind” during the years 1948 to 1950. Papua and New Guinea Agricultural Journal 10 (4): 97–369 (reprinted: 1958. Territory of Papua and New Guinea Fisheries Bulletin no. 1).

[O97] Ogilby, J. D. 1897. On some Australian Eleotrinae. Proceedings of the Linnean Society of New South Wales 21 (4): 725–757.

Pezold, F., & B. Cage. 2002. A review of the spinycheek sleepers, genus Eleotris (Teleostei: Eleotridae), of the western hemisphere, with comparison to the West African species. Tulane Studies in Zoology and Botany 31: 19–63.

Pusey, B., M. Kennard & A. Arthington. 2004. Freshwater Fishes of North-eastern Australia. CSIRO Publishing: Collingwood.

[S58] Smith, J. L. B. 1958. The fishes of the family Eleotridae in the western Indian Ocean. Ichthyological Bulletin 11: 137–163.

[T09] Thacker, C. E. 2009. Phylogeny of Gobioidei and placement within Acanthomorpha, with a new classification and investigation of diversification and character evolution. Copeia 2009 (1): 93–104.

Thacker, C. E., & M. A. Hardman. 2005. Molecular phylogeny of basal gobioid fishes: Rhyacichthyidae, Odontobutidae, Xenisthmidae, Eleotridae (Teleostei: Perciformes: Gobioidei). Molecular Phylogenetics and Evolution 37: 858–871.

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