Question

What are host species of Spirocamallanus pereirai

Answer 1

Procamallanus (Spirocamallanus) is s nematofe that parasitizes several fish species (S.) pereirai was first described from the intestine of Atherinopsis CalifoCaliforniensis. The adults of this nematode has subsequently been reported from a variety of hosts and different geographical localities. The third-stage larva of this nematode was described from the intestine of white shrimps off Mississipi .

In Brasil, the larval stages of Procamallanus were found in freshwater copepods and fish hosts. The finding of a natural infection in different estuarine fishes in this study has revealed for the first time the first-stage larvae of P. (S.) pereirai. This stage is characterized by its translucent color, a dorsal cuticular tooth in the head, the absence of a buccal capsule, an esophagus undifferentiated into an anterior muscular and a posterior glandular regions, and an elongate tail. The second-stage larvae remains unknown, but it probably occurs in copepods, in view of the experimental infections of P. (S.) intestinecolas.

Overstreet (1973) described the third-stage larvae of P. (S.) pereirai from white shrimps Penaeus setiferus and from the spot Leiostomus xanthurus. These larvae were characterized as having a divided, translucent buccal capsule with ridges in the anterior region. The esophagus was already differentiated and the caudal end had four projections, similar to those of P. (S.) pimelodus .

Characteristic features of the fourth-stage larva of P. (S.) pereirai, described herein for the first time, are the buccal capsule, which lacks a distinct basal ring and ridges running to the right, and the caudal extremities with two terminal processes as in the adults.The color of these nematodes can also be used as a differentiating character between adults and larval stages; while the third- and fourth-stage larvae are colorless, adults are reddish. This color was at first associated with the ingestion of blood however, demonstrated the presence of hemoglobin in camallanids distinct from those of the blood of the host, indicating that they probably feed on host food.

The infective third-stage larvae were found together with fourth-stage larvae and adults only in P. brasiliensis and N. Microsoft. Therefore, P. brasiliensis and N. microps appear to be good definitive hosts for P. (S.) pereirai since they have all developmental stages from infective larva to adult. P. brasiliensis is apparently the most suitable host and harbored a large number of mature females, while N. microps had only one mature female. S. tesselatus yielded only fourth-stage larvae and adults and one adult nematode each was collected from the specimens of P. porosissimus and M. americanus examined. The term "paradefinitive" host was defined in relation to the facultative host which partly substitutes the function of the definitive host, attaining the subadult stage without production of eggs or larvae. In this way, S. tesselatus, P. porosissimus and M. americanus could probably be paradefinitive hosts because no gravid female were found. The absence of larvae in P. porosissimus and M. americanus may be related to the small sample size. Only. Among different hosts examined, M. ancylodon, a species which did not yield P. (S.) pereirai, was on the contrary expected to be another potential definitive host due to their preference for preying on P. brasiliensis among other fish . Nevertheless, detailed knowledge of the association of these different hosts with P. (S.) pereirai will be ascertained only when its life-cycle can be fully developed in the laboratory.

Stellifer brasiliensis, Nebris microps, Pori-chthys porosissimus, Symphurus tesselatus and Menticirrus americanus are reported as new host records for P. (S.) pereirai, and the new morphological data on one of the larval stages enhance our knowledge of this life-cycle in the wild.