Aspidoras Mephisto

📖 Overview

This species prefers slow waters (small values of dissolved oxygen), small depths (ca. 0.05 m) and bottom formed by silt, clay and boulders, showing higher values of Total Dissolved Solutes compared to the epigean drainage. Abundance is relatively high compared to other troglobitic fishes (ca. 50 individuals in pools), and population densities of 5±6 inds.m-2. Juveniles were observed along small stretches of the drainage, always in lentic and shallow places, isolated from the adults and frequently under roots. It forages calmly close to small submersed roots and silty-bottom, using the anterior extremity of the snout exploring the substrate in a parallel position or forming an angle of ca. 60° in relation to the bottom, sometimes under the small roots. The fish showed this behavior throughout the entire observation time (ca. 20 min) and did not show escape and/or avoidance behavior due to lamp-light or other external disturbances (e.g. presence of the observer). A detailed courtship behavior at the AneÂsio III cave is shown in a video file (https://www.youtube.com/watch?v=ksrV1af0NZY and https://figshare.com/articles/Aspidoras_mephisto_new_species/4583974). Two individuals were observed close to each other; the smaller one (considered the first male) starts to go around the larger (supposedly the female), and gives gentle touches on the flanks, head and tail. A third individual (the second male) arrives, and then the three stop parallel to each other. After a few seconds, they swim in the opposite direction, the female stops for a few seconds, then swims in the direction of the first male, showing a preference for this individual. However, the second male arrives and the first one swims in the opposite direction, avoiding contact. At this time, the second male, touches abruptly and quickly the female in the flanks and tail, but the female escapes immediately, avoiding the copula. Appearance of several juvenile individuals along the drainage, suggests that the fish were in the reproductive period (dry season); in contrast to the stated behavior of many troglobitic organisms, that show a reproductive peak in the beginning or middle of the rainy season, when food availability and input is higher. One possible explanation is that the AneÂsio-Russão cave-system can sustain the population due the large amount of submerged roots, which represent shelter and food source for this catfish, thus food is probably not the main limiting factor. Captive observations suggest that this species has a high life expectancy, which is a typical characteristic of troglobitic organisms. The holotype captured in adult stage on April 7, 2007 and was kept alive until its preservation, on April 20, 2016 (nine years in captivity). In addition, one of the paratypes, MCP 40634, also captured in adult stage on April 7, 2008 was maintained alive in the aquarium until February 13, 2015 (seven years in captivity). Considering that no evidence or study shows how much time it takes until they reach the adult stage, a minimal life expectancy of at least ten years could be possible for A. mephisto .

🔬 Taxonomy

🐟 Physical Description

This species is distinguished from all of its congeners by the following characters: with a conspicuous reduction of pigmentation and orbit in most specimens; with smaller preadipose azygous plates; presence of dorsal-fin spinelet; parieto-supraoccipital fontanel located mesially on bone; no distinct dark brown or black stripe from anteroventral portion of eye to upper lip lateral area, and absence of striated small platelets on ventral surface of trunk; infraorbital 1 generally with well-developed ventral laminar, or moderately-developed; with poorly-developed serrations on posterior margin of pectoral spine; dorsal fin, even in conspicuously colored specimens, with only dark brown or black chromatophores concentrated on rays, forming spots in some specimens, the membranes hyaline, or with isolated dark brown or black chromatophores on membranes, not forming any conspicuous pattern; nuchal plate not externally visible .: elongated; Cross section: oval.

🌀 Behaviour

Behavioural data for Aspidoras Mephisto is currently being reviewed.

🦐 Diet

🥚 Reproduction

🌍 Habitat & Distribution

Freshwater; demersal. Tropical South America: Brazil.

🌿 Ecology

📐 Morphometrics

🌡️ Water Parameters & Tolerance

📊 Population Risk & Fisheries

🐠 Related Species

🔍 Similar Species

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