Cyprideis kotzianae ( Purper & Ornellas, 1991 )

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 : 17-18

Cyprideis kotzianae ( Purper & Ornellas, 1991)

Figs. 4g –k ; Pl. 3, Figs. 1 –38

pars *1991 Chlamydocytheridea kotzianae Purper & Ornellas , sp. nov. —Purper & Ornellas: 26; Pl. 1, Figs. 8–9 . [non Pl. 1, Fig.

7; holotype]

Material. 207 valves; samples AM 10/3, 15, 19, 23–25, 27–30, 40–41.

Dimensions (total range over all samples; inverse forms not differentiated). R ♀ l = 0.82–1.04 (0.93), h = 0.39–0.50 (0.45; n = 9); L ♀ l = 0.79–1.00 (0.92), h = 0.40–0.49 (0.45; n = 8); R ♂ l = 0.81–0.99 (0.89), h = 0.36–0.45 (0.41; n = 5); L ♂ l = 0.81–1.01 (0.92), h = 0.38–0.46 (0.42; n = 4); Rj(A-1) l = 0.68, h = 0.34 (n = 1); Lj(A-1) l = 0.67–0.71 (0.69), h = 0.33–0.35 (0.34; n = 2).

Remarks. C. kotzianae is similar to C. machadoi , which stimulated Muñoz-Torres et al. (1998) and Whatley et al. (1998) to synonymise both species.

In core 1AS-10-AM both species co-occur with males, females and juveniles in several samples. For this reason and the following differences, we consider this species as a valid taxon: C. kotzianae is smaller; has a more elongated outline with a more equally rounded anterior margin; the hinge elements are weaker developed and characteristically, the selvage runs anteroventrally over a short distance in a straight course in normal right valves and inverse left valves, respectively (compare C. machadoi: Pl. 2, Fig. 21 with C. kotzianae: Pl. 3, Fig. 38). Although the vestibulum varies to some degree in C. machadoi , the anterior vestibulum is much larger in C. kotzianae ( Figs. 4g –k ). Due to a narrower fused zone in C. kotzianae , marginal pore canals are rather short and simple or bifurcated. In C. machadoi , the anterior marginal pore canal openings are large and open between the selvage and flange, flanked by typical marginal ripplets (e.g. Pl. 2, Fig. 21), which are constantly missing in C. kotzianae (e.g. Pl. 3, Fig. 38).

Similar to C. machadoi , the development of the “ Chlamydotheca ”-like flange (in normal left and inverse right valves, correspondingly) as well as size vary between samples (e.g. Pl. 3, Fig. 21, 33 (AM10/30): well-developed flange, large; Pl. 3, Fig. 14, 32 (AM10/25): less developed, small).

In some samples (AM10/23, 3; Pl. 3, Figs. 1 –11) only inverse specimens occur (but never associated with regular valves), which are otherwise identical with normal valves of C. kotzianae . Since an inverse hinge (and reversed valve overlap) is the only difference, we consider this feature as intraspecific variability (but compare C. kroemmelbeini ; see chapter 4.5.3.). Interestingly, inverse C. machadoi -valves have never been observed in the current material. Thus, the hint to inverse hinges in the description of C. machadoi in Muñoz-Torres et al. (1998) most probably refers to inverse C. kotzianae -specimens.

Purper & Ornellas (1991) established C. kotzianae based on material from core 1AS-32-AM (sample depth: 26 m). The holotype —a female left valve (MP-O-1237; Pl. 1, Fig. 7 in Purper & Ornellas 1991)—equals C. machadoi with a well-developed “ Chlamydotheca ”-like flange from the present core (e.g. Pl. 1, Fig. 27). On the other hand, the “male” paratype (carapace MP-O-1238; Pl. 1, Figs. 8–9 in Purper & Ornellas 1991) is identical with C. kotzianae females of our material (e.g. Pl. 3, Fig. 21 and Fig. 10 , an inverse specimen, if mirrored).

We re-sampled the type layer (as far as possible) of core 1AS-32-AM (sample depth: 27.3 m) and found C. kotzianae associated with C. machadoi —analogous as in core 1AS-10-AM (unfortunately, only variants with less developed flange but identical with specimens from AM10/27, 25; compare e.g. C. kotzianae from the “type layer” on Pl. 3, Figs. 12–13 with specimens from AM10/25 on Pl. 3, Figs. 14, 32). We assume that both species have been mixed up during the description of C. kotzianae . Consequently, the female specimen (the holotype; MP-O-1237) belongs to C. machadoi ; it has to be rejected as holotype for C. kotzianae and is excluded from the type series. Nonetheless, C. kotzianae is a distinct, sufficiently described nominal taxon to which the specimens under discussion here belong. We suggest the paratype MP-O-1238 of Purper & Ornellas 1991 (which we believe is a female) as neotype for C. kotzianae in order to clarify the taxonomic status of this species (ICZN 72.4.5, 75.3, recommendation 75A; MP-O-1238 is stored in the collection of the Universidade Federal do Rio Grande do Sul, Porto Alegre).

Finally, Chlamydocytheridea is considered by Whatley et al. (1998) as a junior synonym of Cyprideis . Here we follow their opinion with reservation and Chlamydocytheridea kotzianae Purper & Ornellas, 1991 turns into Cyprideis kotzianae ( Purper & Ornellas, 1991) .

Occurrence (of C. machadoi sensu Muñoz-Torres et al. 1998 ). Western Amazonia ( Brazil, Colombia, Peru), early Middle to early Late Miocene ( C. aulakos – C. cyrtoma zone; Muñoz-Torres et al. 2006; chronostratigraphic correlation after Wesselingh & Ramos 2010). Up to now only distinguished in Brazil (core 1AS-32-AM, depth: 26 m, altitude: 71 m; Purper & Ornellas 1991; plus depth: 27.3 and 121.3 m, pers. observ., M.G.).

4.5.3. olivencai subgroup

Species. C. olivencai and C. kroemmelbeini .

Characters. Subovate–subtrapezoidal; medium sized; smooth, asulcate; no marginal spines; wide inner lamella with large anterior vestibulum; anterior short, branched or ramified (anteroventrally) marginal pore canals; hinge moderately long, approximately equally divided median element.

Figures

FIGURE 1. Location of the study area in western Amazonia. a: Isopatches [m] of the thickness of the Solimões Formation in the Acre and Solimões Basins (after Maia et al. 1977; Latrubesse et al. 2010); b: Coal-prospection area with isopatches [m] of the Solimões Fm. and position of exploration wells (after Maia et al. 1977; star = herein investigated core 1AS-10-AM; additional boreholes marked with numbers are mentioned in this study; location of CPCAN-I–III after Nuttall 1990).

FIGURE 4. “Smooth” Cyprideis species of core 1AS-10-AM (except Figs. j–k = core 1AS-32-AM) photographed in transmitted light (external view) and focus stacked (scale bar = 200 µm; L/R = left/right valve; ♀/♂ = female/male; l/h = length/height [mm], specimen code = sample number_specimen number). a–c: C. amazonica, a: L♂ (0.84/0.46; AM10-39_44), b: R♀ (0.85/0.46; AM10-7_94), c: R♀ (0.74/0.42; AM10-39_42); d–f: C. machadoi, d: L♀ (1.09/0.58; AM10-23_66), e: L♀ (1.06/0.53; AM10-27_74), f: R♂ (1.08/0.51; AM10-27_73); g–k: C. kotzianae, g: R♂ (0.83/0.38; AM10-27_75), h: L♀ (1.00/ 0.46; AM10-30_36), i: R♂? (0.95/0.43; AM10-30_117), j: L♀ (0.87/0.41; AM32-5_26), k: R♀ (0.86/0.40; AM32-5_39); l–m: C. olivencai, l: L♀ (0.73/0.38; AM10-7_97), m: R♀ (0.75/0.38; AM10-7_96); n: C. kroemmelbeini, L♀ (0.83/0.41; AM10- 7_100); o: C. paralela, R♀ (0.61/0.30; AM10-30_100); p–r: C. multiradiata, p: L♀ (0.78/0.37; AM10-30_116), q: L♂ (0.89/ 0.38; AM10-30_114), r: R♂ (0.89/0.37; AM10-30_113).

FIGURE 7. Variation of some traits in C. sulcosigmoidalis (for ornamentation and selvage position specimens were assigned to classes (1–3; ESM 2); if more than one class occur in one sample, the arithmetic mean is also displayed; the number of studied specimens per sample is indicated next to the bars; min = minimum, max = maximum, max range/sa = maximum range within one sample, Rf = right female valves).

FIGURE 8. Ostracod based biozonation of Muñoz-Torres et al. (2006) and remarks (correlations of biozones and chronostratigraphy after Wesselingh et al. 2006b; Wesselingh & Ramos 2010; FAD = first appearance datum and LAD = last appearance datum sensu Muñoz-Torres et al. (2006); s. MT = sensu Muñoz-Torres et al. (1998), s. P = sensu Purper (1979), syn. = synonymous).

FIGURE 9. Stratigraphic range of herein treated Cyprideis species mainly based on Muñoz-Torres et al. (2006; for details see chapters 4.5. and 4.6.; correlations of biozones and chronostratigraphy after Wesselingh et al. 2006b; Wesselingh & Ramos 2010; arrows: probably further extending into the Late Miocene, see Gross et al. 2013).

FIGURE 10. Distribution of Cyprideis species in core 1AS-10-AM and ostracod biozonation (barren samples AM10/45–47 as well as the single valve in AM10/48 not displayed; asterisk at samples AM10/6–7: more (~four times) material available but not counted; for legend of the lithology, see Fig. 1).