Abstract:
A new miniature tridentine catfish is described from
the Rio Purus drainage, Amazon basin, Brazil. It differs
from all other tridentines in having several unique
autapomorphies: conspicuous anteromedial protuberance
in the snout; set of symphyseal premaxillary and dentary
teeth inclined posteromedially; distal process of
the hyomandibula directed anteriorly; rod-like orbitosphenoid
ossified only ventral to the optic nerve; mesethmoid
cornua inclined ventrolaterally; opercular and interopercular
odontodophores separated by a large interspace; basipterygia
fused sagittally; and conspicuous dark brown horizontal
stripe in the middle of the caudal fin. The new taxon
is hypothesised to be sister to the clade formed by
Tridensimilis and Tridens. A detailed
osteological description of the new taxon is provided
based on X-ray microcomputed tomography (µCT-scans)
data and on cleared and stained specimens. Our analysis
also reveals that “Tridens”brevis,
an enigmatic species that has been indecisively assigned
to three different tridentine genera over the past
134 years, belongs to Tridentopsis. Consequently,
Tridensimilis is a monotypic genus that currently
includes only T.
venezuelae (Datovo
A., et al 2023). Etymology:From rhino, latinised form of the Greek word
rhinos (pivós), meaning nose or snout,
and Tridens, the type genus of the subfamily. In allusion
to the rostral protuberance of the new genus. An adjective.The specific name of chromocaudatus:
From chroma, latinised from of the Greek word khrôma
(xpwµa), meaning colour, and cauda,
a Latin word meaning tail. In reference to the presence
of the dark brown pigmentation in the middle of the
caudal fin. An adjective. (Datovo
A., et al 2023). Remarks:
Rhinotridens chromocaudatus was captured
in localities of the lower Rio Purus, including within
the Floresta Estadual Tapauá and Reserva Sustentável
Piagaçu-Purus. No significant threats to the
species have been identified in the area of occurrence.
Consequently, R. chromocaudatus can be provisionally
classified as Least Concern (LC) according to the
categories and criteria of the International Union
for Conservation of Nature (Datovo
A., et al 2023).
Common
Name:
None
Synonyms:
None
Family:
Trichomycteridae
Distribution:
South America:Rio Ipixuna, Rio Purus drainage, Rio Amazonas
basin, Humaitá Municipality, Amazonas State,
Brazil.
Size:
1.5cm. (1¼ins)
Temp:
22-26°c (71-79°f.)
p.H.
6.0-7.0.
Reference:
Datovo A, Ochoa L,
Vita L, Presti P, Ohara WM, de Pinna MCC.
A new genus and species of miniature tridentine catfish
from the Amazon basin (Siluriformes: Trichomycteridae).
Neotrop Ichthyol. 2023; 21(3). Fish
in the News
Rhinotridens chromocaudatus Rio Ipixuna, tributary of the Rio Purus, Rio Solimões
basin, Brazil
Rhinotridens
chromocaudatus Dorsal view-Rio Ipixuna, tributary of the Rio Purus,
Rio Solimões basin, Brazil
Rhinotridens
chromocaudatus Ventral view-Rio Ipixuna, tributary of the Rio
Purus, Rio Solimões basin, Brazil
Rhinotridens
chromocaudatus Type locality-Rio Ipixuna, Rio Purus drainage, Rio
Amazonas basin, Humaitá Municipality, Amazonas State, Brazil
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