Somalis piauiensis, Barros & Oliveira, 2023

Barros, Olga Alcântara & Oliveira, Paulo Victor De, 2023, New Dendrobranchiata fossil preserved in the Brazilian Cretaceous (Aptian / Albian) from the Araripe Basin, Piauí State, Zootaxa 5264 (4), pp. 545-563 : 550-551

Somalis piauiensis n. sp.

( Figures 5–14 )

Type material: LPP CR 001p (part), and LPP CR 001cp (counterpart), holotype.

Type locality: municipality of Caldeirão Grande do Piauí, Piauí State .

Stratigraphic unit: Romualdo Formation, Santana Group, Araripe Basin.

Age: Early Cretaceous-Albian

Etymology: The specific epithet was derived from the locality where the material was collected. It derives from the state of Piauí, northeast Brazil, and this choice was due to this being the first record of fossil shrimp occurrence in this region of the Araripe Basin.

Diagnosis: The same as for the genus.

Description: Fossil preserved in lateral view. Small Penaeoidea with a total length of approximately 15 mm (rostrum to telson). Carapace laterally compressed; antennal and branchiostegal spines present. Long rostrum, with thirteen evident dorsal spines yielding a serrate appearance. Moderately preserved corneas with light pigmentation, wider than eyestalk.Antennal protopodite preserved, antennule incompletely preserved. Laminar scaphocerite large, lateral margin weakly rounded, longer than rostrum. Third maxillipeds not preserved. Second part of the pereiopods scarcely preserved and with a chelate appearance, pleopods on the second somite poorly laterally preserved, the third to fifth not preserved. Pleon laterally compressed, six-segmented, all somites without spines. Pleura of the second pleonal somite overlapping with the third but not the first; the first and second somites approximately the same size, the third slightly larger, and the fourth and fifth somites approximately the same size; the sixth somite elongated and approximately twice the length of the previous somites. Telson smaller than uropods, the lateral margin weakly rounded.

Figures

FIGURE 5. LPP CR 001cp. A) Lateral view of Somalis piauiensis n. gen. n. sp. B) Reconstitution of the sample. Rs: Rostrum; An: Antennule; E: Eyes; A: Antenna; S: Scaphocerite; P2: Pereiopods; Pl: Pleopods; I–VI: Pleonal somites; T: Telson; U: Uropods. Scale bars: 1 mm. Photo and drawing by Olga A. Barros.

FIGURE 6. LPP CR 001cp. A) Detail of the carapace and pereopod. B) Detail of the large scaphocerite. Rs: Rostrum; An: Antennule; A: Antenna; E: Eyes, S: Scaphocerite; P2: Pereiopods. Photo by Olga A. Barros.

FIGURE 7. LPP CR 001cp. A) Detail of the rostrum and eyes, B) As: Antennal spine, Bs: branchiostegal spine. Arrow shows the base of the scaphocerite. Photo by Olga A. Barros.

FIGURE 8. LPP CR 001cp. A and B) Details of the smooth pleon without spines (I–VI), showing the pleura of the second pleonal somite overlapping with the third but not the first. Pl: Pleopods. Photo by Olga A. Barros.

FIGURE 9. LPP CR 001cp. A) Details of the sixth somite. B) Uropods and telson. VI: Pleon; T: Telson; U: Uropods. Photo by Olga A. Barros.

FIGURE 10. LPP CR 001cp. Second part of the pereiopods scarcely preserved and with a chelate appearance. Photo by Olga A. Barros.

FIGURE 11. LPP CR 001p. Lateral view of Somalis piauiensis n. gen. n. sp. Rs: Rostrum; An:Antennule; A:Antenna; E; eyes, S: Scaphocerite; P2: Pereiopods; Pl: Pleopods; I–VI: Pleon; T: Telson; U: Uropods. Scale bar: 1 mm. Photo by Olga A. Barros.

FIGURE 12. LPP CR 001p. A) Detail of the carapace. Laminar scaphocerite large, lateral margin weakly rounded, longer than rostrum. B) Long rostrum, with thirteen evident dorsal spines yielding a serrate appearance. Rs: Rostrum; An: Antennule; E: Eyes. S: Scaphocerite. Photo by Olga A. Barros.

FIGURE 13. LPP CR 001p. A) Smooth pleon without spines, pleura of the second abdominal somite overlapping the third but not the first. B) Detail of pleon III–VI. Pl: Pleopods; I–VI: Pleon. Photo by Olga A. Barros.

FIGURE 14. LPP CR 001p. A) The sixth somite is more elongated than the others. Detail of pleon V and VI. B) Detail of the uropod. T: Telson; U: Uropods. Photo by Olga A. Barros.