Cottus “bairdii-cognatus” complex

[Espinasa and Jeffery 2003]



Espinasa and Jeffery (2003) recorded a troglomorphic fish population from a cave in Pennsylvania, USA. They do not differentiate it taxonomically from epigean fishes in the Cottus bairdi-cognatus complex. The following details refer only to the troglomorphic fishes.






Since the troglomorphic population has not been considered as a separate taxon there are no designated types. Espinasa and Jeffery (2003) do not record any museum reference numbers.


Type locality: Eiswert #1 Cave, Nippenose Valley, Lycoming County, Pennsyvania, USA (41o9’23.2”N, 77o12’21.1W). Known also from Tytoona Cave, near Altoona, Blair County, Pennsylvania (Espinasa et al. 2013).


Eiswert #1 Cave is a small vadose stream segment between a sink and a rising. It is likely that the hydrological connection between the downstream end of the cave and the rising is passable to fishes moving up and down stream. There is therefore potentially some degree of connection between epigean and hypogean populations.


The taxonomic position of the troglomorphic taxon is not clear. Two species from which it may be derived, Cottus bairdi and C. cognatus, together with hybrids between the two, are found in the vicinity of Eiswert #1 Cave. The diagnostic characters used to separate these species (3 pelvic fin rays in C. cognatus, 4 pelvic rays in C. bairdi and hybrids) is difficult to apply as fin ray reduction may be a troglomorphic character. It is likely that molecular techniques will be required to resolve this question.

Conservation Status


Since this species is known only from only one locality it is minimally VU D2. Luis Espinasa reports (pers. comm.) that a large pig farm is to be built on the karst surface directly above Eiswert #1 Cave. This would certainly be detrimental to the fishes in the cave. It is encouraging that Espinasa and Jeffery (2003) explicitly cover conservation status in their account of this species. They rightly consider that this population should be protected under the United States Endangered Species Act.

Museum Holdings

None known.

Internet Resources

Tytoona Cave web site

Tytoona Cave Nature Preserve Management Plan

Tytoona Cave Wikipedia entry

A brief account with photographs

Key References

Robins, C.R. Thesis 1954 A taxonomic revision of the Cottus bairdi and Cottus carolinae species group in eastern North American (Pisces, Cottidae)
Williams, J. D. and Howell, W. M. Journal Article 1979 An albino sculpin from a cave in the New River drainage of West Virginia (Pisces: Cottidae)
Troester, JW and White, WB Journal Article 1984 Seasonal fluctuations in the carbon dioxide partial pressure in a cave atmosphere
Jones, W.R. and Jannsen, J. Journal Article 1992 Lateral line development and feeding behaviour in the mottled sculpin, Cottus bairdi (Scorpaeniformes, Cottidae)
Coombs, S. Journal Article 1999 Signal detection theory, lateral‐line excitation patterns and prey capture behaviour of mottled sculpin
Coombs, S., Finneran, J.J. and Conley, R.A. Journal Article 2000 Hydrodynamic image formation by the peripheral lateral line system of the Lake Michigan mottled sculpin, Cottus bairdi.
Brison, L.L. Thesis 2001 Experimental analysis of metabolic adaptation of Cottus carolinae in response to photoperiod and food availability
Coombs, S, Braun, CB and Donovan, B Journal Article 2001 The orienting response of Lake Michigan mottled sculpin is mediated by canal neuromasts.
Kanter, MJ and Coombs, S Journal Article 2003 Rheotaxis and prey detection in uniform currents by Lake Michigan mottled sculpin (Cottus bairdi)
Espinasa, L and Jeffery, WR Journal Article 2003 A troglomorphic sculpin (Pisces: Cottidae) population: Geography, morphology and conservation status
Robins, CR Journal Article 2005 Cottus kanawhae, a new cottid fish from the New River System of Virginia and West Virginia
Cahill, A Journal Article 2013 Hybridization and the colonisation of the cave environment by fish
Espinasa, L, Cahill, A, McCaffery, S and Millar, C Journal Article 2013 Partial sequence of a gene involved in skin colouration (MC1R) from the Pennsylvanian Grotto Sculpin
Espinasa, L., Mendyk, A., Schaffer, E. and Cahill, A. Journal Article 2013 The Second Northernmost Cave-adapted Fish in the World? Groundwork on the Tytoona Cave Sculpin Population
McCaffery, S., Collins, E. and Espinasa, L. Journal Article 2014 Eye histology of the Tytoona Cave Sculpin: Eye loss evolves slower than enhancement of mandibular pores in cavefish?
Ruppert, JLW, James, PMA, Taylor, EB, Rudlofsem, T, Veillard, M, Davis, CS, Watkinson, D and Poesch, MS Journal Article 2017 Riverscape genetic structure of a threatened and dispersal limited freshwater species, the Rocky Mountain Sculpin (Cottus sp.)
Gebhard, A.E and Perkin, J.S. Journal Article 2017 Assessing riverscape-scale variation in fish life history using banded sculpin (Cottus carolinae)
Baek, S.Y., Kang, J.H., Jo, S.H., Jang, J.E., Byeon, S.Y., Wang, J.H., Lee, H.G., Choi, J.K. and Lee, H.J. Journal Article 2018 Contrasting life histories contribute to divergent patterns of genetic diversity and population connectivity in freshwater sculpin fishes