Ischyrocerus Conlan, 2021, n. comb.

• Main Author: Conlan, Kathleen E.
• Format: Other/Unknown Material
• Language: unknown
• Published: 2021
• Subjects: Biodiversity; Taxonomy; Animalia; Arthropoda; Malacostraca; Amphipoda; Ischyroceridae; Ischyrocerus; Arctic; Arctic Ocean
• Online Access: https://zenodo.org/record/4534337; https://doi.org/10.5281/zenodo.4534337

Genus Ischyrocerus n. comb. Supplementary Table S4 Type species. Ischyrocerus anguipes Krøyer, 1838 Diagnosis (with differences from Neoischyrocerus in bold). Body length at maturity 2–18 mm, though most species are> 5 mm long at adulthood. Primarily known from the Northern Hemisphere in cold temperate to polar waters from 32°N (La Jolla, California; J.L. Barnard 1969) to 81°N in the Arctic Ocean (Stephensen 1944), collected from algae, hydroids, crabs or substrate unknown, 1 to ~ 2000 m. Widely known in Europe but not in the Southern Hemisphere, although one species was found at 42°S off of Chile (J.L. Barnard 1964). Pereon: dorsally smooth (most species), ridged or carinate (some species). Antenna 1: accessory flagellum 2 articles (second minute), flush with the flagellum or rarely projecting forward; antenna 2 peduncle article 4, 115–170% wider than antenna 1 peduncle article 2 (or rarely equal width), setae and setal pattern similar to antenna 1 or setae shorter, occasionally plumose. Gnathopod 2, adult male: 100–220% the length of gnathopod 1, basis usually not especially elongate, propodus elongate and slender or short and broad (rarely similar to gnathopod 1); coxa 1 70–140% the depth of coxa 2; basis concave or straight; ischium anteriorly rounded or straight; propodus variably shaped, slender or broad (posterior length 120–290% of central width), palm only on the distal portion of the propodus or nearly the full length of the propodus, without a bulge or tooth defining it proximally at the junction of the carpus, palm variously toothed; dactyl 33–75% the length of the propodus. Gnathopod 2, juvenile male: shorter than the adult male gnathopod 2, palm bearing 1–2 strong spines about midway along the length of the propodus, dactyl ending at the spines. Gnathopod 2, female: only slightly larger than gnathopod 1, palm of the propodus convex or concave. Pereopods 3 and 4: propodus, posterior margin bearing setae but not spines; c oxa 4, posterior margin straight to shallowly concave. Pereopod 5, male: ...