Foregut morphology of Pseudothelphusidae and Trichodactylidae (Decapoda: Brachyura) from northeastern Pará, Brazil

Abstract

ABSTRACT. The gross morphology of foregut was investigated and described in detail for four freshwater crab species: a pseudothelphusid, Fredius reflexifrons (Ortmann, 1897) and three trichodactylids -Sylviocarcinus pictus (H. MilneEdwards, 1853), Valdivia serrata White, 1847, and Dilocarcinus septemdentatus (Herbst, 1783). In general, the gastric mills of freshwater crabs showed a similar degree of complexity in relation to other marine species of Anomura and Brachyura previously described in the literature. However, significant morphological differences were observed among the analyzed species, as in ossicle numbers, features and connection types. A total of 38 ossicles were described for S. pictus and V. serrata and 37 ossicles for D. septemdentatus and F. reflexifrons, respectively. The latter species can be distinguished from the others by the presence of a wide cardiac sac resembling two sacs. Most of the ossicles were connected through a rigid connection, and few ossicles were fused. The degree of calcification varied little among the studied species. The differences found among the species suggest that the morphological aspects of the foregut may be useful in the identification of similar species.

Foregut morphology of Macrobrachium carcinus (Crustacea, Decapoda, Palaemonidae)

“…The opening between the cardiac stomach and esophagus in M. carcinus is not guarded by especial valves as reported for other crustaceans (Brösing 2010;Alves et al 2010), but by esophageal plates. As already reported for M. malcolmsoni, M. acanthurus, M. rosenbergii and Palaemonetes argentinus Nobili 1901 (Felgenhauer and Abele 1989;Thonggamgaew 2004;Sousa and Patriella 2006).…”

“…The cardiac and pyloric chambers are sustained by chitinous ossicles joined to each other by ligaments enabling their articulation; however, it is numerically and morphologically varied in Decapoda (Hobbs and Hooper 2009;Alves et al 2010;Reimann et al 2011). The number of ossicles observed in the cardiac stomach of M. carcinus is higher comparativelly to other caridean prawns (Mocquard 1883;Patwardhan 1935b).…”

Comparative morphology of the stomach ossicles of four freshwater crabs species of Dilocarcinini (Crustacea, Decapoda, Trichodactylidae)

“…Nevertheless, in some cases the ossicles of young specimens, regardless of sex, were more decalcified than in the adults, but still conspicuous, such as the pyloric ossicles, the anterior inferior-pyloric ossicle and some plaques. This is also the case for D. septemdentatus, thus differing from the results of Alves et al (2010), who only recognized 37 ossicles.…”

“…Lima-Gomes et al (2017) also recognized these plates in V. serrata and S. pictus and, similarly, we observed them in all four species studied herein. Nevertheless, Alves et al (2010) did not recognize these plates in D. septemdentatus.…”

“…The dorsomedian and dorsolateral cardiac plates were not mentioned in the studies of Mocquard (1883), Brösing (2010), or Alves et al (2010). In the study of Lima (2010) these plates were observed with distinct calcification in some species of Uca Leach, 1814 and Ucides Rathbun, 1897 and, according to the author, were recognizable in all the stomachs analyzed, but only slightly calcified.…”