Metadata

Ogilbia galapagosensis

(Poll and Leleup, 1965) Cohen and Nielson 1978

Ogilbia galapagosensis
Redrawn by Rhian Kendall from Poll and Leleup (1965)
ORDERSUB-ORDERFAMILY
OphidiiformesBythitoideiDinematichthyidae

Synonyms

Caecogilbia galapagosensis  Poll and Leleup 1965

Country

Galapagos

Types

Holotype: MRAC uncatalogued male 51.5mm SL. Allotype: female 47.0mm SL. Paratypes: male 39.0mm SL, male 49.0mm SL, male 55mm SL, female 40mm SL, female 48mm SL. Moller et al. (2005) report that no specimens of this species could be found at MRAC, any other major Museum, or the Charles Darwin Station on the Galapagos Islands. This species is the type species by monotypy of the genus Caecogilbia.

Distribution

Type locality: a number of deep fissures situated between the lagoon of "Flamants roses", about 2 km west of Turtle Bay, close to Charles Darwin Station, Santa Cruz Island, Galapagos (0o37’S, 90o21’W). Grove and Lavenberg (1997:20,224) comment that this species: “... is known only from fresh and brackish waters in crevices on Santa Cruz near Bahia Tortuga [= Turtle Bay] and Punta Las Palmas ...”. Poll and Leleup (1965:464) suggested that the species may be distributed throughout Santa Cruz but this seems unlikely in view the studies of Grove and Lavenberg. Snell, Stone and Snell (1996) summarise the geography of Galapagos and should be consulted by anyone studying there.

Habitat

Fissures constitute the only points of access to an extensive area of more or less brackish ground water. This probably underlies the whole island in a Ghyben-Herzberg lens but all of the fishes observed were seen between 500 m and 1 km of the coast. The degree of salinity decreases with distance from the sea. This is an anchialine habitat (see Iliffe 1991, 1992, 2000). Individuals appear to live among roots of Cryptocarpus vegetation (DeRoy 1974, Grove and Lavenberg 1997:224). The presumed sister species, Ogilbia deroyi (Poll and Van Moll 1966), inhabits: “...loose rocks and boulders in shallow intertidal water...” (Grove and Lavenberg 1997:221). The comparative ecology of O. galapagosensis and O. deroyi were studied by Van Mol (1967).

Systematics

Cohen and Nielsen (1978) placed this species in the genus Ogilbia. This species is probably evolved from the very similar Ogilbia deroyi (Poll and Van Moll 1966, DeRoy 1974). Individuals of O. galapagosensis vary considerably in colour, from brown through to pink, and also in eye size and body shape. D.M. Cohen (in Grove and Lavenberg 1997:224) has suggested that the different morphs may be separate species. Van Mol (1967) made a comparative anatomical study of O. galapagosensis and O. deroyi.

Morphological and molecular studies by Moller et al. (2016) showed that thew genus Ogilbia is sister to Ogilbichthys and both are sister to the subterranean fish Typhlias pearsei. Ogilbia and Ogilbichthys diverged 20 million years ago and both diverged from the monotypic Typhlias 30 million years ago. These studies also showed that Ogilbia galapagosensis is a member of the tribe Dinematichthyini together with two other subterranean species Typhlias pearsei and Diancistrus typhlops. They also raised the tribe to the level of Family, Dinematichthyidae Whitley 1928, and all three subterranean species are now placed in this Family and removed from Bythitidae.

Conservation Status

[VU D2:3.1:2010]

(Nielsen, J.G., Munroe, T., Tyler, J. & Robertson, R. 2010. Ogilbia galapagosensis. The IUCN Red List of Threatened Species 2010. http://dx.doi.org/10.2305/IUCN.UK.2010-3.RLTS.T15184A4499879.en. Downloaded on 10 July 2017).

Museum Holdings

As above only.

Key References

Poll, M. and Leleup, N. Journal Article 1965 Un poisson aveugle nouveau de la famille des Brotulidae provenant des iles Galapagos
Poll, M. and Van Mol, J.J. Journal Article 1966 Au sujet d'une espece inconnue de Brotulidae littoral des iles Galapagos, apparentee a l'espece aveugle Caecogilbia galapagosensis Poll et Leleup
Van Mol, J.J. Journal Article 1967 Ecologie comparee de deux especes de Brotulidae (Pisces) des iles Galapagos: Caecogilbia deroyi Poll et Van Mol 1967 et C. galapagosensis Poll et Leleup 1965
Van Mol, J.J. Journal Article 1967 Etude anatomique du genre Caecogilbia Poll et Leleup
Leleup, N. and Leleup, J. Journal Article 1968 Mission zoologique belge aux iles Galapagos et en Ecuador. Resultats scientifiques
DeRoy, T. A. Journal Article 1974 Discovering a new species
Suarez, S.S. Journal Article 1975 The reproductive biology of Ogilbia cayorum, a viviparous brotulid fish
Cohen, D. M. and Nielsen, J. G. Journal Article 1978 Guide to the identification of genera of the fish order Ophidiiformes with a tentative classification of the order
Iliffe, T. M. Book Section 1991 Anchialine fauna of the Galapagos Islands.
Peck, S. B. and Finston, T. L. Journal Article 1993 Galapagos Island troglobites: The question of tropical troglobites, parapatric distribution with eyed sister species, and their origin by parapatric speciation
Peck, S. B. Journal Article 1994 Diversity and zoogeography of the non-oceanic crustacea of the Galapagos Islands, Ecuador
Peck, S. B. Book Section 1994 Ecuador
Snell, H.M, Stone, P.A. and Snell, H.L Journal Article 1996 A summary of geographical characteristics of the Galapagos Islands
Grove, J. S. and Lavenberg, R. J. Book 1997 The fishes of the Galapagos Islands
Nielsen, J. G., Cohen, D. M., Markle, D.F. and Robins, C. R. Journal Article 1999 Ophidiiform fishes of the world (Order Ophidiiformes). An annotated and illustrated catalogue of pearlfishes, cusk-eels, brotulas and other ophidiiform fishes known to date
Moller, P.R., Schwarzhans, W. and Nielsen, J.G. Journal Article 2005 Review of the American Dinematichthyini (Teleostei: Bythitidae). Part II. Ogilbia
Moller, P.R., Knudsen, S.W., Schwarzhans, W. and Nielsen, J.G. Journal Article 2016 A new classification of viviparous brotulas (Bythitidae) – with family status for Dinematichthyidae – based on molecular, morphological and fossil data