Scoloplax dicra
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Siluriformes
Family: Scoloplacidae
Genus: Scoloplax
Species:
S. dicra
Binomial name
Scoloplax dicra
Bailey & Baskin, 1976

Scoloplax dicra is a species of spiny dwarf catfish.

Geographic range and habitat

Scoloplax dicra has the widest distribution in the family Scoloplacidae, encompassing the Amazon and Paraguay River basins, particularly the Rio Maronon/Ucayali drainage of Peru, Rio Mamore/Guaporé of Brazil, lower basin of the Rio Negro, in its northernmost distribution, as well as the upper Rio Madeira, tributaries of Rio Solimões, Rio Purus and Rio Juruá basins. [2][3]

Scoloplax dicra live in stagnant, oxbow lagoons that are heavily shaded by lowland forests.[4] Species of Scoloplax inhabit waters with slow currents, blackwater, and muddy, silty, or sandy bottoms, and have a presence of riparian and submerged vegetation.[5] The preferred habitat is acid waters with organic detritus on the bottom.[4]

Physical description

The relationships of Scoloplax lie among the armored catfish groups, with well-developed integumentary teeth on the fins, head, and usually on the separate bony plates on the body.[4] Scoloplax dicra has a subterminal mouth with bifid teeth in a single row in both upper and lower jaws. Gills extend from the lower pectoral base to the upper corner of the operculum with short gill rakers. Four branchiostegal rays. A pair of lateral bony spheres encapsulate swim bladder vesicles, each with sharp lateral projections. The dorsal and pectoral spines have locking mechanisms. Fin rays: dorsal I,4; anal I,4 or 5; pectoral I, 5 to 7; pelvic I,4; caudal 10 or 11.[4] The anal fin is short and rounded while the pelvic fin is relatively long with three to four soft rays and the adipose fin is absent. The maxillary barbel extends to just beyond the insertion of the pectoral fin with the barbel forks behind the angle of the mouth—no nasal barbel.[4] The standard length ranges from 9 to 20 mm.[2] Scoloplax dicra also has the characteristic of a pair of bony plates with 3 odontodes, located between the pelvic-fin base and anus has not been recorded in any other Scoloplax species.[5] It also has 27 total vertebrae, a condition shared with outgroup loricariids.[6]

Life cycle

The reproductive biology of Scoloplacaids is still poorly known, Scoloplax dicra might be an inseminating species, based on the histological identification of spermatozoa within the ovaries.[7] Scoloplacidae has exhibited marked sexual dimorphism.[8] It is suggested that these fish reproduce early during the rainy season from November on, and afterward, most of the adult population dies.[9]

Not much is known about the longevity of this species. It is likely that such a small tropical fish has an annual life cycle.[4] This would help explain a lack of living adults after the rainy season when they have reproduced.

Economic importance

The small size and secretive habits of Scoloplacidae preclude any aquaculture use.[10]

Conservation status

Although not many specimens have been collected, its wide distribution does not raise concerns about conservation, particularly because the habitat where they are found is very common in the region.[3] But, because this region is a potential hotspot for freshwater fishes, the area should be managed due to the narrow floodplain in the region. Zoning and restrictions should be put in place to minimize the impact on the region.[11] The distribution of this species lies within multiple countries which could make management of the species difficult.

References

  1. ↑ Brejão, G.L. (2021). "Scoloplax dicra". IUCN Red List of Threatened Species. 2021: e.T49830154A160407963. doi:10.2305/IUCN.UK.2021-1.RLTS.T49830154A160407963.en.
  2. 1 2 Schaefer, S. A.; Weitzman, S. H.; Britski, H. A. (1989). "Review of the Neotropical catfish genus Scoloplax (Pisces: Loricarioidea: Scoloplacidae) with comments on reductive characters in phylogenetic analysis". Proceedings of the Academy of Natural Sciences of Philadelphia (141): 181–211. S2CID 89274329.
  3. 1 2 Rocha, M. S.; Lazzarotto, H.; Py-Daniel, L. (2012). "A new species of Scoloplax with a remarkable new tooth morphology within Loricarioidea (Siluriformes: Scoloplacidae)". Copeia. 2012 (4): 670–677. doi:10.1643/CI-11-142. JSTOR 41827085. S2CID 86615694.
  4. 1 2 3 4 5 6 Bailey, R. M.; Baskin, J. N. (1976). "Scoloplax dicra, A new armored catfish from the Bolivian Amazon". Occasional Papers of the Museum of Zoology University of Michigan (674): 1–14. hdl:2027.42/57110.
  5. 1 2 Albornoz-Garzon, J. G.; et al. (2018). "First records of the family Scoloplacidae (Siluriformes, Loricarioidei) in Columbia, including a range expansion of Scoloplax baileyi Rocha, Lazzarotto & Py-Daniel, 2012". Check List. 14 (6): 1071–1046. doi:10.15560/14.6.1071.
  6. ↑ Schaefer, S. A. (1990). "Anatomy and Relationships of the Scoloplacid Catfishes". Proceedings of the Academy of Natural Sciences of Philadelphia. 142: 167–210. JSTOR 4064976.
  7. ↑ Spadella, M. A.; Oliveira, C.; Quagio-Grassiotto, I. (2008). "Morphology and Histology of Male and Female Reproductive Systems in Inseminating Species Scoloplax distolothrix (Ostariophysi: Siluriformes: Scoloplacidae)". Journal of Morphology. 269 (9): 1114–1121. doi:10.1002/jmor.10647. PMID 18553423. S2CID 36337061.
  8. ↑ Meisner, A. D.; Burns, J. R.; Weitzman, S. H.; Malabarba, L. R. (2000). "Morphology and Histology of the Male Reproductive System in Two Species of Internally Inseminating South American Catfishes, Trachelyopterus lucenai and T. galeatus (Teleostei: Auchenipteridae)". Journal of Morphology. 246 (2): 131–141. doi:10.1002/1097-4687(200011)246:2<131::AID-JMOR7>3.0.CO;2-K. PMID 11074580. S2CID 12170785.
  9. ↑ Sazima, I.; Machado, F. A.; Zuanon, J. (2000). "Natural history of Scololplax empousa (Scoloplacidae), a minute spiny catfish from the Pantanal wetlands in Western Brazil". Ichthyological Exploration of Freshwaters. 11 (1): 89–95.
  10. ↑ Teugels, G. G. (1996). "Taxonomy, phylogeny and biogeography of catfishes (Ostariophysi, Siluroidei): an overview". Aquatic Living Resource. 9 (S1): 9–34. doi:10.1051/alr:1996039. S2CID 84736853.
  11. ↑ Chernoff, B.; et al. (2000). "Fishes of three Bolivian Rivers: Diversity, Distribution and Conservation". Interciencia. 25 (6): 273–283.
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