Morphometric relationships and reproductive traits of the deep-sea armored shrimp <i>Glyphocrangon spinicauda</i> A. Milne-Edwards, 1881 (Decapoda: Caridea: Glyphocrangonidae) from the southeastern Gulf of Mexico

ABSTRACT Biological information on Glyphocrangon spinicauda A. Milne-Edwards, 1881, a western Atlantic deep-sea armored shrimp, is scant. This species occurs in the Gulf of Mexico, but at low abundance, in the southern (Mexican) part. We obtained a sample of 203 G. spinicauda at depths of 244–455 m during a research cruise exploring the biota of the upper continental slope of the southeastern Gulf of Mexico, off the Yucatán Peninsula. We examined morphometric and allometric relationships of the shrimp as well as some reproductive traits based on the number and size of embryos. Sex ratio (1.4 females:1 male) differed significantly from unity. Females had significantly larger total length (TL) and total weight, but not carapace length (CL), than males, suggesting that females have proportionally larger abdomens. All morphometric relationships were significant for both sexes and most were linear. Relationships against CL were mostly isometric, but TL and rostral length exhibited negative allometry, i.e., a proportionally smaller increase with increasing CL. Brood size (BS) and embryo mass volume were linearly related with female size, but embryo development stage significantly affected BS, embryo size, embryo mass volume, and reproductive output. We found a significant, negative relationship between residuals of the number and size of embryos, suggesting a trade-off in embryo production. Although G. spinicauda is of no commercial value, it co-occurs with other species of potential interest. Our results can thus be useful to design management and conservation plans should fisheries for deep-sea resources eventually develop in the southern Gulf of Mexico.