Subterranean Fishes of the World

Country

Types

Holotype: MBM/F/16/10 37.8mm TL, 31.0mm SL. Paratype: (3) 32.0mm-36.0mm TL.

Distribution

A dugout well (10.2m deep) at Irinjalakuda, Trichur District, Kerala, India, 10°20'47.50"N, 76°12'03.50"E.

Habitat

Shallow groundwaters.

Systematics

Jayaram (2006:309) proposed the subfamily Horaglanidinae for the, then, two species in the genus but this has not received support since.

Diogo et al. (2003), also de Pinna (1993) and de Pinna (1998), have suggested, on morphological grounds, that the most basal member of the Family Clariidae is Horaglanis, and that the next most basal is Uegitglanis.

Biological Notes

The Kerala area of south-western India, principally the area of the Western Ghats, is rich in subterranean species. There are at least three unique elements within this subterranean fauna that stand out as of great evolutionary interest.

First, there are at least eight subterranean fishes: Clariidae: H. krishnai, Horaglanis alikunhii, Horaglanis abdulkalami; Kryptoglanidae: Kryptoglanis shajii, Kryptoglanis undescribed species; Synbranchidae: Monopterus eapeni, Monopterus roseni, Monopterus digressus.

Second, there is a strongly fossorial amphibian in its own family: Nasikabatrachidae: Nasikabatrachus sahyadriensis Biju and Bossuyt 2003, sister family, genus and species to Sooglossidae, an amphibian family found only in the Seychelles archipelago) (Zachariah et al. 2012).

Third, there are two aberant Crustacea: Euryrhynchidae: Eurindicus bhugarbha De Grave, Arjun and Raghavan 2018 and Palaemonidae: Troglindicus phreaticus Sankolli and Shenoy 1979.

Both the fishes and the Crustacea appear to have originated in Gondwanan times and both have close relatives in Africa. It is hypothesised that the genus Horaglanis is related to Uegitglanis zammaranoi from Somalia (Menon 1951, Silas 2010) and Eurindicus is related to three west African species (the monotypic Euryrhyncoides holthuisi, Euryrhynchina edingtonae and Eurhynchina puteola (De Grave et al. 2018).

There is considerable evidence, both from morphology and molecules, that Horaglanis is very basal within Clariidae. de Pinna (1993, 1998) and Diogo et al. (2003) considered the skull structure of specie swithin the Clariidae and concluded that Uegitglanis was sister to all other species in the family and that Horaglanis was sister to Uegitglanis plus other species making it the most basal of all studied clariids. This conclusion was supported by Pavan-Kumar (2017) who compared mitochondrial COI sequences from one (unnamed) species of Horaglanis and 13 other Clariidae and showed that it is the sister group to all other species in the family (he did not include Uegitglanis in his analysis). [Note than Pavan-Kumar (2017) is a Peerj preprint that had not been refereed so its conclusions need to be taken with caution.]

Museum Holdings

As above only.