Halomonhystera parasitica n. sp. (Nematoda: Monhysteridae), a parasite of Talorchestia brito (Crustacea: Talitridae) in Portugal

Abstract

Halomonhystera parasitica n. sp. (Monhysterida: Monhysteridae) is described from the bodycavity and under the dorsal plates of the sandy beach amphipod Talorchestia brito Stebbing (Crustacea: Talitridae) in Portugal. The new species differs from previously described members of the genus by a combination of the following characters: four medium-sized cephalic setae; base of stoma with three blunt denticles; posterior dilated portion of stoma absent; amphids small, with width less than quarter of corresponding body width; amphids located less than two labial widths from anterior extremity; uterine eggs elliptical and unembryonated; gubernaculum lacks caudal process; and male tail with two separated pairs of postcloacal papillae and a single subterminal seta-like papilla. This is the first representative of the family Monhysteridae parasitic in the body-cavity of crustaceans. Approximately 48% of the amphipods examined contained various stages of H. parasitica.

The Geological Record of Parasitic Nematode Evolution

“…Early hosts of nematode parasites of invertebrates were probably representatives of Tetradonematidae, Marimermithidae, Echinomermellidae, Benthimermithidae, Monhysteridae and Leptolaimidae (see Poinar (2011) for the systematic placement of these groups) that today parasitize marine ostracods, copepods, shrimp, amphipods and isopods (Petter, 1980;Poinar et al, , 2009, starfish (Asteroidea) (Rubtsov and Platonova, 1974;Rubtsov, 1977), brittle stars (Ophiuroidea) (Ward, 1933), sea urchins (Echinoidea) (Gemmill and Von Linstow, 1902;Jones and Hagen, 1987), priapulids (Rubtsov, 1980), polychaetes (Petter, 1983), tubicifid oligochaetes (Hallett et al, 2001), foraminifera (Hope and Tchesunov, 1999) and marine nematodes (Chesunov, 1988;Tchesunov and Spiridonov, 1993). Some of these host groups, such as polychaetes, ostracods and foraminifera, have fossil records extending back to the Cambrian (Lehmann and Hillmer, 1983).…”

The Evolutionary History of Nematodes

“…This scenario is supported by the discovery that representatives of the Mermithidae, Tetradonematidae, Marimermithidae, Echinomermellidae, Benthimermithidae, Monhysteridae and Leptolaimidae parasitise marine ostracods, copepods, shrimp, amphipods and isopods (Petter, 1980;Poinar et al, , 2009, starfish (Asteroidea) (Rubstov & Platonova, 1974;Rubstov, 1977), brittle stars (Ophiuroidea) (Ward, 1933), sea urchins (Echinoidea) (Gemmill & von Linstow, 1902;Jones & Hagen, 1987), priapulids (Rubstov, 1980), polychaetes (Petter, 1980), tubicifid oligochaetes (Hallett et al, 2001), foraminifera (Hope & Tchesunov, 1999) and marine nematodes (Tchesunov, 1988;Tchesunov & Spiridonov, 1993). Some of these host groups, such as polychaetes, ostracods and foraminifera, have fossil records extending back to the Cambrian and, in the case of polychaetes, possibly the Precambrian (Lehmann & Hillmer, 1983).…”

“…Some nematodes may have developed in the egg nests of the above groups. Members of the widespread nematode family Monhysteridae are not only free-living in the sea, but also occur on the gills, under the body plates and in the body cavities of various crustaceans (Poinar et al, 2009). Some forms even appear to burrow into the shell of horseshoe crabs (Leibovitz & Lewbart, 2004), organisms that have a fossil record extending back to the Silurian. The diverse habitats found during the Cambrian (marine, brackish water, freshwater, terrestrial) probably led to nematode diversification and associations were established with other organisms.…”

“…They are extremely rare as fossils and Dominibrentus leptus Poinar, 2009 in Dominican amber (Poinar, 2009b) was associated with a diplogastrid nematode (Fig. 157).…”

“…Wood-boring insects, especially Scolytidae and Platypodidae, are known to cohabit their galleries with diplogastrids, which then form phoretic associations with the beetles (Rühm, 1956;Massey, 1974 (Massey, 1974). Poinar, 2009 (Coleoptera: Brentidae). Vol.…”