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).
britskii is distinguished from R. acuen,
R. bockmanni, R. chromodontus, R.
dani, R. dinizae, R. hera,R. jumaorum, R. pentakelis, R.
marginalis n. sp., and R. loxochelis
n. sp. by possessing an adipose fin (vs. adipose fin
absent), and by having a Y-shaped light mark from
the snout tip to each nostril (vs. light mark V-shaped
or present as two separate lines from snout tip diverging
to each nostril. It is distinguished from R. collinsae,
R. halbolthi, and R. hardmanni by
lacking accessory teeth on both premaxilla and dentary
(vs. accessory teeth present ); the odontodes on the
ventral surface of first pelvic-fin ray bent and pointing
mesially (vs. odontodes aligned with main ray axis
); a triangular dark spot on the anterior portion
of the dorsal-fin membrane (vs. dorsal-fin spot absent);
a Y-shaped light mark from snout tip to nostrils (vs.
Y-shaped light mark absent); and a larger orbit, 27.8–39.0%
snout length (vs. orbit 18.9–24.6% snout length).
Rhinotocinclus britskii is distinguished
from R. eppleyi, R. longirostris,
R. polyochrus, R. variola, R.
yaka, R. discolor n. sp., R.
sp., and R. pilosus n. sp. by having the
snout more broadly rounded (Fig. 12B; vs. snout more
acutely pointed ); dark bars on body narrower and
more widely spaced (Fig. 7A; vs. dark bars on body
wider and closer together, Fig. 7B); and one plate
between the posterior border of the rostral plate
and the nostril (Fig. 12B; vs. 2–4 plates, Fig.
12A). It is distinguished from R. kwarup
by having fewer premaxillary teeth (15–29, mode
23, vs. 28–34, mode 32), and fewer dentary teeth
(15–29, mode 20 and 25, vs. 27–33, mode
29 ); and by having the colour pattern with less broken
marks (vs. colour pattern with more broken marks,
& Lehmann 2022).
Aquarium Care: This is a dwarf species which
can be problematic to keep as it will need to be kept
by their own or at least with other dwarf species
as they will find it difficult to compete for food
in the hurly burly of a community tank. Diet:
Artemia naupli and vegetable matter. Remarks:
Most online searches at the moment (2022) will still
give you the old genus name of Parotocinclus.
Orinoco River basin and Atlantic coastal drainages
of the Guianas. Type locality: Left
tributary of Coppename River, Surinam, 3º51'N,
Evers, H.-G. &
I.Seidel: Mergus, Baensch Catfish Atlas Volume
1, 1st English edn., 2005. Pp.944. Ferraris, C.J. Jr., 2007. Checklist
of catfishes, recent and fossil (Osteichthyes: Siluriformes),
and catalogue of siluriform primary types. Zootaxa
1418:1-628. 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. Schaefer, S.A. and F. Provenzano
1993 The Guyana Shield Parotocinclus: systematic,
biogeography, and description of a new Venezuelan
species (Siluroidei: Loricariidae). Ichthyol. Explor.