Hyastenus hilgendorfi (De Man, 1887)

Osman, Marwa M., Sallam, Wafaa S., Madkoura, Fedekar F. & Wicksten, Mary K., 2021, Morphology of camouflage by encrustation in the spider crabs Schizophrys dahlak and Hyastenus hilgendorfi (Decapoda: Brachyura: Majoidea: Epialtidae) from the Suez Canal, Egypt, Journal of Natural History 55 (33 - 34), pp. 2047-2064 : 2054

Hyastenus hilgendorfi (De Man, 1887)

The carapace of H. hilgendorfi is distinguished by the presence of clusters of spinules located only on the orbital regions ( Figure 4 (a)). Each cluster comprises 27–55 short, tooth-shaped spinules with pointed tips ( Figure 4 (b)).

Nine setal forms belonging to three main types (hooked, pappose and cuspidate) and a novel one (frilled spatulate setae) were found and photographed. No distinct differences were observed among size ranges for males or for females. A description is given for each setal type /form encountered, including average widths and lengths, presence of substructures and their average lengths as well as areas of the integument where the setal type was mainly encountered. No pores were present on any of the described forms. All setal types showed infracuticular articulation.

Figures

Figure 4. Hyastenus hilgendorfi. (a) Clusters of spinules on orbital regions; (b) close-up of a cluster; (c) arrow indicates typical hooked seta on the exoskeleton; (d) annuli on the basal region of the setal shaft of hooked setae indicated by arrow; (e) arrow indicates hair-like setules of pappose setae, randomly distributed on the medial and distal portions of setal shaft; (f) arrow indicates tendri-pappose setae with thread-like setules randomly distributed on proximal and distal portions of setal shaft; (g) cuspidate setae on the exoskeleton; (h) air-dried wedged setae on exoskeleton; (i) critical-pointdried wedged setae.