Apseudopsis adami, a new species of tanaidacean (Crustacea: Peracarida) from the NW Iberian Peninsula: postmarsupial development and remarks on morphological characters

Abstract

A new species of apseudomorph tanaidacean, Apseudopsis adami sp. nov., is described, including intraspecific variation, from specimens collected in the seagrass meadows of O Grove inlet (NW Iberian Peninsula, NE Atlantic). The new species is characterized by the unique combination of the following characters: pointed rostrum with rounded shoulders, four ventral propodal spines on pereopod 1, and posterolateral pointed apophyses on pereonites 2-5, regardless of the developmental stage of the individual. Two juvenile stages were identified before reaching maturity; early juvenile limbs are scarcely ornamented in comparison to the adults. Advanced juveniles represent the vast majority of the studied population, and the limb ornamentation is similar to that of the adults. Males show two different cheliped morphologies. After a preparatory stage, females pass through a sequence of copulatory instars followed by intermediate stages in which the female loses the ovisac after manca release. The number of segments of the antennular and antennal flagella and uropod endopods, as well as the development and ornamentation of the mandibular palp, are meristic changes that occur during development and allow rapid identification of the developmental instar.

A Hidden Diversity in the Atlantic and the SE Pacific: Hamatipedidae n. fam. (Crustacea: Tanaidacea)

“…The low abundance of deep-sea populations often represented by a few individuals in the samples precludes studying a life cycle of deep-sea Tanaidacea. The knowledge we currently have on life history and reproductive strategies of deep water tanaids comes from observations on only a few shallow-water species that we extrapolate to deepwater species (see Esquete et al, 2012;Rumbold et al, 2014;Gellert and Błażewicz, 2018;Stępień et al, 2021). The material we investigated was unique, as one species -H. mojito was represented by 127 individuals at different developmental stages, which allowed us to make a series of measurements of total body length, body segments and uropodal rami.…”

New data on the Tanaidacea (Crustacea: Peracarida) from the Canary Islands, with a description of a new species of Apseudopsis

“…Remarks. Species of Apseudopsis are distinguished by a combination of characters that do not vary through the developmental stages, as follows (see Esquete et al, 2012a): Shape of the rostrum, presence of apophysis on pereonites, presence or absence of dorsodistal spine on pereopod 1 merus, and number of ventral spines on pereopod 1 propodus. Other diagnostic characters include the number and position of hyposphenia on juveniles II and females, and features of the male II cheliped.…”

“…Apseudopsis Norman, 1899 is a tanaidacean genus that inhabits sedimentary bottoms in temperate waters worldwide. It comprises a total of 23 species (Anderson 2015) five of them distributed in the East Atlantic: Apseudopsis adami Esquete & Bamber (see Esquete et al 2012a); A. arguinensis (Guţu, 2002); A. cuanzanus Bochert, 2012; A. isochelatus Guţu, 2006 andA. latreillii (Milne-Edwards, 1828).…”