A new genus has been erected,
Rhinotocinclus, (2022) with the type species
of Parotocinclus longirostris Garavello,
1988. Abstract: A new genus of Hypopopomatinae
armored catfish is described from the northern portions
of South America, namely the Amazon, Orinoco and Guianan
coastal drainages. The new genus is diagnosed from
all remaining hypoptopomatines by having the canal
cheek plate on the ventral surface of the head posteriorly
elongated and contacting the cleithrum, in addition
to other features that distinguish the new genus from
specific genera. Five new species are described and
18 species currently allocated in Parotocinclus,
Hisonotus, and Curculionichthys
are transferred to the new genus and rediagnosed.
Parotocinclus amazonensis and P. aripuanensis
are considered junior synonyms of P. britskii.
The secondary sexual dimorphism of the members of
the new genus is detailed and illustrated. Morphological
characters are used to delimit four phenotypic groups
of species that might have phylogenetic significance,
which still have to be properly tested. A key to the
species is offered and diagnoses, illustrations, and
distribution maps are provided for all species (Reis
& Lehmann 2022).
Description: Rhinotocinclus loxochelis
is distinguished from all congeners by having the
dominant colour pattern formed by four dark bars on
body somewhat fragmented and inclined, such that they
connect to form a zig-zag pattern (vs. dominant colour
pattern formed by dark bars separated and distinct,
or dark bars wide and partially coalesced, or formed
by a dark stripe from the snout tip, through the eye
and extending to end of caudal peduncle). Rhinotocinclus
loxochelis is further distinguished from R.
britskii, R. discolor, R. eppleyi,
R. isabelae, R. kwarup, R. longirostris,
R. pilosus, R. polyochrus, R.
variola, and R. yaka by lacking an adipose
fin (vs. adipose fin present). Rhinotocinclus
loxochelis is further distinguished from congeners,
except R. marginalis, R. bockmanni,
R. dani, and R. pentakelis, by having
small platelets at adipose-fin position (vs. small
platelets absent). Rhinotocinclus loxochelis
is distinguished from R. bockmanni by lacking
a triangular dark spot at the dorsal-fin membrane
(vs. dorsal-fin dark spot present), and from R.
hera by having yellow teeth cusps (vs. light
ochre cusps). Rhinotocinclus loxochelis is
further distinguished from R. marginalis
by the dark bar 2 on body reaching to the ventral
midline (vs. dark bars on body barely passing lateral
dark stripe), and by the deeper caudal peduncle 10.3–11.2%
vs. 9.1–10.1% SL) and longer pectoral-fin spine
(30.4–32.1% vs. 26.7–30.3% SL); and from
R. dani by the deeper body (body depth 18.3–20.4%
vs. 16.3–18.3% SL, caudal peduncle depth 10.3–11.2%
vs. 8.8–9.9% SL, and head depth 44.9–49.4%
vs. 38.0–43.5% HL). (Reis
& Lehmann 2022).
Etymology: Rhinotocinclus masc.,
from the Greek ????s (Rhinos), beak, snout and Otocinclus,
a genus of Hypoptopomatinae, in allusion to the conspicuous
and elegant snout of most of its species. Rhinotocinclus
loxochelis, from the Greek (loxos), slanting,
crosswise, and (kelis), stain, spot, in allusion to
the broken and oblique dark bars of the species. A
noun in apposition (Reis
& Lehmann 2022).
South America:Known from creeks tributary to the rio Jamanxim,
rio Tapajós basin, in the Jamanxim National
Forest, Pará, Brazil.
Reis RE, Lehmann A.
P. A new genus of armored catfish (Siluriformes:
Loricariidae) from the Greater Amazon, with a review
of the species and description of five new species.
Neotrop Ichthyol. 2022.