Is Copytus Skogsberg, 1939 (Crustacea: Ostracoda) a neocytherideid? With description of a new family and two new species
Author
Coimbra, João Carlos
Author
Bergue, Cristianini Trescastro
Author
Ramos, Maria Inês Feijó
text
Zootaxa
2020
2020-01-29
4729
2
177
194
journal article
24222
10.11646/zootaxa.4729.2.2
b44745ed-b90a-4b62-b636-23c48c56471a
1175-5326
3632249
EC42F789-C869-4551-998E-CC819044C775
Copytus cuspidata
sp. nov.
(
Fig. 2
: 1–5;
Tab. 1
)
2005
Copytus
sp. 1 Machado
et al.
: 240, pl. 1, fig. 15.
Etymology.
Latin, with reference to the pointed anteroventral margin.
Type locality.
Southern Brazilian continental shelf,
REMAC
Project, sample L1-3115 (32°21’;
50°46’W
,
74 m
water depth, silt).
Age.
Recent.
Material.
38 Recent valves of adult and juveniles, and six Quaternary fossil valves.
Holotype
.
MP-O-2752 LV, l:
0.68 mm
, h:
0.22 mm
(sample L1-3115)
.
Paratypes
.
MP-O-2753
RV
, l:
0.65 mm
, h:
0.22 mm
(sample L1-3115); MP-O-2754 LV, l:
0.68 mm
, h:
0.23 mm
(sample GVI-350)
.
Diagnosis.
Medium sized carapace. Anterior margin extremely protruded in the ventral half. Surface with longitudinal delicate but conspicuous ribs, somewhat concentric posteriorly, absent in the central region. Ribs and a moderately deep fossa converging anteroventrally. Inner lamella wide, particularly anteriorly.
Description.
Carapace medium sized, thin shelled, and subcylindrical. Anterior margin extremely protrud- ed in ventral half, slightly convex in dorsal half. Posterior margin symmetrically rounded. Dorsal margin long and straight. Ventral margin parallel with dorsal one. Cardinal angles obtuse. Maximum length subventral. Height evenly uniform along the carapace. Height equals about 1/3 length. Shell surface with longitudinal delicate but well-defined ribs, somewhat concentric posteriorly, absent in the central region. Ribs and a moderately deep fossa converging anteroventrally. Inner lamella wide, particularly anteriorly. Anterior vestibule large, very deep. Selvage very narrow, indistinct. Marginal pore canals few, simple, short anteriorly and posteriorly. Hinge adont. As is common to the genus, the adductor scars are hidden, except in one adult valve, as follows: a subrounded group of four subtriangular imprints. Sexual dimorphism not visible in the studied isolated valves.
Geographic and stratigraphic distribution.
In our study, this species was found between the
Rio Grande do Sul State
(
33°51’S
) and the
Rio de Janeiro State
(
22°55’S
) (see
Tab. 1
). Six fossil specimens were encountered in Quaternary sediments of the upper slope of
Santa Catarina State
in six cores (see ‘Material and Methods’).
Machado
et al.
(2005)
recorded this species off Cabo Frio town,
Rio de Janeiro State
, however, they did not report the number of specimens collected. In a pers. comm. in
April 2018
, Cláudia Pinto Machado informed the first author that the distribution by sample was not published in 2005, but that five valves of
Copytus cuspidata
sp. nov.
were collected between 61 and
70 m
on silt or fine sand.
Remarks.
The present species bears some resemblance to
Copytus fusiformis
(
Yassini, 1979
)
, inasmuch as it has the anterior margin protruded in the ventral half and a ribbed surface. However, in
C. cuspidata
sp. nov.
the carapace is much smaller, less fusiform and more ornamented, besides some differences in outline.