Keijcyoidea praecipua ( Bold, 1963 )

Antonietto, Lucas Silveira, Machado, Cláudia Pinto, Carmo, Dermeval Aparecido Do & Rosa, José Wilson Correa, 2012, Recent Ostracoda (Arthropoda, Crustacea) from São Pedro-São Paulo Archipelago, Brazil: a preliminary approach, Zootaxa 3335 (1), pp. 29-53 : 32-33

Keijcyoidea praecipua ( Bold, 1963) emend.

Fig. 4 :1–15

1963 Cytherelloidea praecipua Bold , p. 75, pl. 1, figs. 1−7.

1967 Cytherelloidea praecipua Bold. Hullings , p. 655, figs. 4:p, 7:n.

1971 Cytherelloidea praecipua Bold. Allison & Holden , p. 209, fig. 31.

1974 Cytherelloidea praecipua Bold. Swain & Gilby , p. 277, pl. 1, figs. 5−6, text fig. 6c.

1975 Cytherelloidea praecipua Bold. Teeter , p. 490, fig. 23m.

1978 [non] Cytherelloidea sp. cf. C. praecipua Bold. Khosla , p. 257, pl. 1, fig. 7.

1981 Cytherelloidea sp. aff. C. praecipua Bold. Bate et al. , p. 4, fig. 2:A.

1985 [non] Cytherelloidea aff. praecipua Bold. Carreño , p. 142, pl. 3, figs. 6−7.

1992 Keijcyoidea praecipua (Bold) . Coimbra et al., p. 96, pl. 3, fig. 10.

2006 [non] Keijcyoidea praecipua (Bold) . Hussain et al., p. 1663, fig. 6:7.

?2008 Keijcyoidea praecipua (Bold) . Gopalakrishna et al., p. 301.

Original diagnosis. A species of Cytherelloidea with reticulate carapace and longitudinal ridges, characterized by a strong tooth that is situated on the dorsal margin of the left valve and fits into a socket in the dorsal margin of the right valve ( Bold 1963).

Emended diagnosis. Carapace with rounded alveoli along the anterior end and ventral margin of the left valve in the adult stage. Lateral surface reticulated in the intra-ridge regions and partly over the ridges, and finely punctated at the central and centroventral areas. Pronounced sexual dimorphism: females larger than males; ventral margin straight in females and concave in males; in dorsal view, greatest width posterior in females and posteromedian in males.

Holotype. HVH no. 6833 ( Bold 1963).

Type locality. Pigeon Point, Tobago, calcareous sands ( Bold 1963).

Material. 71 specimens (MP-612, MP-747 and MP-748).

Figured specimens. CP-436, CP-441 and CP-548 (carapaces); CP-437, CP-438, CP-439, CP-440, CP-441, CP-442, CP-443, CP-445 (valves) ( Tab. 1).

Geographic and stratigraphic distribution. Pigeon Point, Trinidad and Tobago ( Bold 1963); Clipperton Island, Eastern Pacific Ocean, Overseas France ( Allison & Holden 1971); San Juan del Sur, Nicaragua ( Swain & Gilby 1974); South Stann Creek and Tobacco Entrance, Belize ( Teeter 1975); São Pedro-São Paulo Archipelago, Brazil, Recent.

Description. Carapace subretangular in lateral view, with greatest height and length along the median region. Right valve larger, strongly overlapping the left valve along the dorsal and ventral regions and slightly at the anterior end. Dorsal margin concave at the anteromedian portion. Anterior end rounded, with outline ornamented by small denticle-like structures. Posterior end straight, forming an 80–90º cardinal angle with the dorsal margin. Lateral surface reticulated in most of the intra-ridge regions, and partially over the ridges, and punctated in the median and anteromedian areas; in the left valve, also ornamented with a series of rounded to elliptical alveoli along the anterior end and ventral margin. Three ridges present: one extending through the ventromedian region, and the other from the dorsocentral to the dorsoposterior region, where both are connected by a third oblique ridge. Internal view as described for the genus. Pronounced sexual dimorphism: females larger than males; ventral margin nearly straight in females and concave in males; greatest width posterior for females and posteromedian for males.

Remarks. Generic diagnosis follows Malz (1981), while species diagnosis follows Bold (1963). The original description for Keijcyoidea praecipua was based on six specimens. According to it, these were: a female carapace (holotype), along with three other carapaces, two females and one male, and two female valves (paratypes). Despite its separation into genders by the original author, all specimens look very similar. It is believed that all previously described specimens were males, and the true female for the species is the one herein presented for the firsttime. Differences between males and females in K. praecipua , therefore, resemble those observed in K. keiji ( McKenzie 1967) , a morphologically close species ( McKenzie 1967; Titterton & Whatley 2006). Specimens identified as Cytherelloidea praecipua in Allison & Holden (1971), Swain & Gilby (1974) and Teeter (1975) look much like the females described by the present study, despite small differences in size and ornamentation details, and are considered as belonging to the same species. The material studied by Gopalakrishna et al. (2008) in the Indian Ocean has not been illustrated; therefore, the authors prefer to keep in doubt the occurrence registered in that work.

Figures

FIGURE 4. Ostracods from São Pedro-São Paulo Archipelago, Northeastern Brazil. 1–15. Keijcyoidea praecipua (Bold, 1963) emend. 1–3. Adult carapace, CP-436 (♀). 1. Right view. 2. Left view. 3. Dorsal view. 4–6. Adult valve, CP-445 (♀). 4. Left internal view. 5. Interpretation of the hinge tooth in detail. 6. Interpretation of the central muscle scar in detail. 7–8. Adult carapace, CP-548 (♂). 7. Right view. 8. Dorsal view. 9. A-1 valve, CP-437, left view. 10. A-2 valve, CP-438, left view. 11. A-3 valve, CP-439, left view. 12. A-4 valve, CP-440, right view. 13. A-5 carapace, CP-441, left view. 14. A-6 valve, CP-442, right view. 15. A-7 carapace, CP-443, right view. 16–22. Neonesidea tenera? (Brady, 1886) emend. Maddocks, 1969. 16–18. A-1? carapace, CP-448. 16. Right view. 17. Left view. 18. Dorsal view. 19. A-2? carapace, CP-450, right view. 20. A-3? valve, CP- 451, right view. 21. A-5? valve, CP-452, right view. 22. A-7? carapace, CP-453, right view. Scale = 100 µm.