Parapseudidae Guţu, 1981

Drumm, David T. & Heard, Richard W., 2022, Mexctenapseudes boeschi, a new tanaidacean genus and species (Crustacea: Peracarida: Apseudomorpha: Parapseudidae) from the Mexican coast of Campeche with the designation of a new related Australian genus to receive Longiflagrum caeruleus (Boesch, 1973), Zootaxa 5116 (2), pp. 200-222 : 202

Family Parapseudidae Guţu, 1981

The family Parapseudidae was established by Guţu (1981) to include those apseudomorphan genera lacking a spiniform apophysis on the coxa of the first pereopods. Guţu (2008) revised the family and presented a key to the known genera. Since this revision three genera have been added to the family ( Heard & Morales-Núñez 2011; Bamber et al. 2012; Bamber 2013).

Parapseudids appear to be mainly restricted to the tropical and temperate coastal and shelf waters and less than 10% of the nominal species are presently known from depths greater than 200 m (see Guţu 2008, p. 45). At present, including the two new genera and the new species from the Southwest GoM established in this paper, the subfamily Parapseudinae now contains 70 species representing 20 genera and the Pakistanapseudinae with 24 species representing 10 genera ( Anderson 2020). The two subfamilies are primarily distinguished from each other by the length, width, and armature of the pleonites in relation to the pereon, and the morphology of their pleopods.

Although relatively little is known of the ecology of the Pakistanapseudinae, its species usually occur in high salinities on soft-bottom substrata at mid and lower latitudes. At present, no representatives are reported from lowsalinity inshore habitats, similar to those occupied by members of the Discapseudes -Halmyrapseudes Complex. Many of the morphological characters exhibited by the pakistanapseudins appear to be plesiomorphic and distinctive (e.g., sexually dimorphic male antennule of some taxa), suggesting that this group, like that of the Complex, may have become differentiated and morphologically defined during the Permian prior to the Permian-Triassic Extinction (P-TEx) events.

In reviewing the literature for taxonomic and morphological criteria related to the designation of the new Mexican parapseudid genus, we conclude that the Australian species Longiflagrum caeruleus ( Boesch, 1973) exhibits a unique combination of characters that warrant the establishment of a monotypic genus to receive it. A dichotomous key to the 20 genera of the subfamily Parapseudinae , including those two diagnosed here, is presented below.