Cyprideis matorae, Gross & Ramos & Piller, 2014

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 : 30-31

Cyprideis matorae n. sp.

Figs. 6l–m ; Pl. 12, Figs. 1 –14

? 2011 Cyprideis sp. 3 —Linhares et al.: 95, 98; Fig. 3 /15.

Holotype. Right female valve, AM10-30 _103 (Inv. No. MPEG-445-M; coll. Museu Paraense Emílio Goeldi, Belém; Pl. 12, Figs. 3–4 , 7 , 12–13).

Paratypes. Additionally figured specimens ( Figs. 6l–m ; Pl. 12, Figs. 1–2 , 5–6 , 9–10 ; coll. Museu Paraense Emílio Goeldi, Belém).

Additional material. 91 adult and 14 juvenile specimens from samples AM10 /22, 30 (Inv. No. UMJG & P 211.038 ; coll. Universalmuseum Joanneum, Department for Geology & Palaeontology, Graz) .

Type locality. Borehole 1AS-10- AM at Sucuriju close to Rio Ituí (S 04°50’ / W 70°22’, ~ 62 km SW Benjamin Constant; municipality Atalaia do Norte, state of Amazonia, Brazil) .

Type horizon. Sample AM10 /30 (= depth: 141.2 m, altitude: - 56.2 m) .

Derivation of name. After “Sucuriju”, native name for a mythic giant anaconda, which was called “matora” (bull eater) by conquistadores.

Diagnosis. A subtriangular Cyprideis -species ornamented with a low, polygonal reticulum and 7–9, thick anterior spines along the entire anterior margin. Right valves with one massive posteroventral spine and additional 3–4 smaller spines above; left valves with one, robust posteroventral spine.

Description. Subtriangular outline in lateral view (females and males). Surface reticulated, anteroperipherally almost smooth; the dorsomedian sulcus forms a dorsomedian depression; flange anteromarginally and posteroventrally very thick, forming a robust rim and a posteroventral extension in left valves; 7–9, blunt or robustconical anteromarginal spines along the entire anterior margin; up to 5 posteroventral spines in right valves with the spine in the posteroventral corner being the longest; one robust posteroventral spine in left valves. Scattered, roundish normal pores of sieve type. Inner lamella moderately wide with numerous straight, simple, occasionally branched marginal pore canals; avestibulate. Hinge (right valve): anterior element elongate with ~10 toothlets; short, crenulated anteromedian element; moderately long posteromedian element consisting of a crenulated bar; posterior element with ~7 toothlets; hinge elements of left valve complementary. Central muscle scars with 4 adductor scars, 1 U- or V-shaped frontal and 2 mandibular scars (the upper one roundish; the lower, oval one located close to the ventral margin); prominent fulcral point (knob). Sexual dimorphism: males are slightly more elongated with a more oblique posterior margin; the posterior proportion is wider in females (dorsal view) than in males.

Dimensions (total range over all samples). R ♀ l = 0.73–0.79 (0.76), h = 0.39–0.41 (0.40; n = 3); L ♀ l = 0.80, h = 0.43 (n = 1); R ♂ l = 0.71–0.81 (0.76), h = 0.35–0.39 (0.37; n = 2); L ♂ l = 0.77–0.85 (0.80), h = 0.38–0.42 (0.40; n = 3).

Remarks. Only few, well-preserved specimens are available from sample AM10/30 (sample AM10/22 yields more, but badly preserved material). Nevertheless, this species is well characterised by its distinct subtriangular outline, its low, polygonal reticulum and its massive posteroventral flange in left valves, armed with a strong posteroventral spine. Possibly, Cyprideis sp. 3 of Linhares et al. (2011) represents a male specimen of this species.

The most similar species are C. curucae and, especially, C. ituiae . However, the latter (Pl. 11) is subrectangular (the dorsal margin is less inclined towards the posterior); the muri of its reticulum are much thicker (tending towards a punctated surface ornament); it has a groove-like sulcus (in C. matorae the sulcus forms a dorsomedian depression); it lacks a posteroventral spine in left valves; its posteroventral flange in left valves is less prominent; characteristic distally widened spines occur not along its entire anterior margin. C. ituiae is smaller where it cooccurs with C. matorae .

C. curucae (Pl. 8, Figs. 10 –23) has a less tapered posterior end (the posterior margin is less oblique); it lacks a posteroventral spine in left valves and the extended posteroventral flange; its inner lamella is much wider; its anteromarginal and posteroventral spines as well as the ornament are completely different compared to C. matorae . C. curucae is larger where both species co-occur.

C. matorae resembles to some degree Cyprideis longispina ( Purper, 1979) and C. graciosa but clearly diverge in outline, ornament and development of spines (e.g. Purper 1979; Muñoz-Torres et al. 1998; Gross et al. 2013; see chapter 4.6.2.).

Occurrence. Western Amazonia ( Brazil), latest Middle to early Late Miocene ( C. obliquosulcata – C. cyrtoma zone; this study; possibly as Cyprideis sp. 3 of Linhares et al. 2011 in core 1AS-31-AM (depth: 172.40 m, altitude - 70.40 m); assigned to C. caraionae zone ( Linhares et al. 2011) but possibly younger (? C. obliquosulcata zone) due to occurrence of C. cyrtoma ).

4.6.4. “Ornate” species not attributed to subgroups

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 3. Western Amazonian Cyprideis species groups. a: Phylogenetic model of Muñoz-Torres et al. (2006; Whatley et al. 1998); chronology and phylogenetic relations (stippled lines) redrawn form Muñoz-Torres et al. (2006); taxonomic rearrangements in group allocations in grey (C = Cyprideis, s. MT = sensu Muñoz-Torres et al. (1998), syn. = synonymous); b: herein proposed grouping, based exclusively on morphologic similarities (species without photographs = revision pending).

FIGURE 5. Variation in length of right female valves (Rf) in core 1AS-10-AM of some more frequent Cyprideis species (min = minimum, max = maximum, max range/sa = maximum range within one sample; aside the box plots the number of measured specimens per sample is indicated).

FIGURE 6. “Ornate” Cyprideis species of core 1AS-10-AM photographed in transmitted light (external view) and focus stacked (scale bar = 200 µm; for abbreviations, see Fig. 4). a–b: C. cyrtoma, a: R♀ (0.73/0.37; AM10-27_15), b: R♀ (0.79/ 0.41; AM10-30_51); c: C. schedogymnos, R♀ (0.77/0.39; AM10-42_20); d: C. aff. graciosa, R♂ (0.95/0.48; AM10-30_68); e: C. minipunctata, R♀ (0.80/0.44; AM10-42_26); f: C. curucae, R♀ (0.80/0.42; AM10-23_06); g: C. pebasae, L♀ (0.67/0.36; AM10-27_79); h–i: C. munoztorresi, h: L♀ (0.74/0.39; AM10-15_23), i: R♀ (0.75/0.38; AM10-15_25); j–k: C. ituiae, j: L♀ (0.64/0.33; AM10-23_105), k: R♀ (0.68/0.35; AM10-30_118); l–m: C. matorae, l: L♀ (0.80/0.43; AM10-30_121), m: R♂ (0.81/0.39; AM10-30_120); n: C. inversa, L♂ (0.58/0.32; AM10-30_122); o: C. sulcosigmoidalis, R♀ (1.01/0.59; AM10- 7_47).

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 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).