Cyprideis cyrtoma Muñoz-Torres, Whatley & Van Harten, 1998

Gross, Martin, Ramos, Maria Ines F. & Piller, Werner E., 2014, On the Miocene Cyprideis species flock (Ostracoda; Crustacea) of Western Amazonia (Solimões Formation): Refining taxonomy on species level, Zootaxa 3899 (1), pp. 1-69 : 22-23

publication ID	https://doi.org/ 10.11646/zootaxa.3899.1.1
publication LSID	lsid:zoobank.org:pub:D78F2010-08E1-45C0-86FF-7F2D3601070D
persistent identifier	https://treatment.plazi.org/id/017587FE-FFB9-FFD1-71F4-DAE2FA8CFC15
treatment provided by	Felipe
scientific name	Cyprideis cyrtoma Muñoz-Torres, Whatley & Van Harten, 1998
status

Treatment

Figs. 6a–b View FIGURE 6 ; Pl. 5, Figs. 31–46; Pl. 6, Figs. 1 View FIGURE 1 –21, 23

1998 Cyprideis sp. 1 —Whatley et al.: 236; Text-fig. 2; Pl. 3, Figs. 6–10 View FIGURE 6 View FIGURE 7 View FIGURE 8 View FIGURE 9 View FIGURE 10 .

* 1998 Cyprideis cyrtoma sp. nov. —Muñoz-Torres et al.: 94–96; Text-fig. 2; Pl. 2, Figs. 15–19.

2011 Cyprideis cyrtoma —Linhares et al.: 95, 98; Figs. 3 View FIGURE 3 /7–8.

Material. 421 valves; samples AM 10/3, 16, 22–23, 25, 27, 29–30.

Dimensions (total range over all samples). R ♀ l = 0.68–0.87 (0.75), h = 0.34–0.47 (0.39; n = 77); L ♀ l = 0.73–0.95 (0.82), h = 0.38–0.52 (0.43; n = 12); R ♂ l = 0.74–0.97 (0.83), h = 0.35–0.46 (0.39; n = 10); L ♂ l = 0.77–0.99 (0.87), h = 0.37–0.49 (0.42; n = 7); Rj(A-1) l = 0.57–0.66 (0.61), h = 0.32–0.38 (0.35; n = 5); Lj(A-1) l = 0.58–0.65 (0.61), h = 0.33–0.35 (0.34; n = 4).

Remarks. C. cyrtoma is characterised by its “parallel” anterodorsal and anteroventral margins, which cause a well-expressed oral concavity in both valves. Typically, the anterior valve surface is almost smooth, while the posterior proportion (but not peripherally) is ornamented with puncta ( Muñoz-Torres et al. 1998). The differences to the closely related C. schedogymnos are discussed in the remarks for this species (see below).

Within core 1AS-10-AM considerable variability is observed in size ( Fig. 5 View FIGURE 5 ), outline, and especially in the degree of ornamentation: e.g. the rather large valves of sample AM10/30 are almost smooth (Pl. 6, Figs. 9 View FIGURE 9 –16); the small individuals in AM10/27 are coarsely punctated (also in front of the sulcus; Pl. 6. Figs. 1–8 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 View FIGURE 7 View FIGURE 8 ); in AM10/23 small, “smooth” and punctated valves as well as specimens with truncated and rounded posterior margin co-occur (Pl. 5, Figs. 39–46); the very large valves in AM10/3 are coarsely punctated (Pl. 5, Figs. 31–37).

Well ornamented specimens of C. cyrtoma come close to the herein described C. aff. graciosa (see chapter 4.6.1.) but have a more horizontally aligned posteroventral spine, sitting on a more prominent flange (right valves); the shorter anterior spines are restricted to the lower half of the anterior margin; the ornament along the anterior margin is smoother, and they are slightly smaller.

Further, C. longispina from the Eirunepé area ( Gross et al. 2013) is similar but has a more elongated outline with an additional extension of the posteroventral flange (right valve) above the posteroventral projection, carrying regularly only one spine and no further denticles. The anterior proportion is more strongly ornamented.

Occurrence. Western Amazonia ( Colombia), latest Middle to early Late Miocene ( C. obliquosulcata – C. cyrtoma zone; Muñoz-Torres et al. 2006; chronostratigraphic correlation after Wesselingh & Ramos 2010).