Pachychelium Stephensen 1925

• Main Authors: Lowry, J. K., Stoddart, H. E.
• Format: Text
• Language: unknown
• Published: Zenodo 2012
• Subjects: Biodiversity; Taxonomy; Animalia; Arthropoda; Malacostraca; Amphipoda; Pakynidae; Pachychelium; Lowry; Pacific; Seta; Antarc*
• Online Access: https://dx.doi.org/10.5281/zenodo.5251234; https://zenodo.org/record/5251234

Pachychelium Stephensen, 1925 Pachychelium Stephensen, 1925: 121. ― Schellenberg, 1926: 296. ―Schellenberg, 1931: 18. ―K.H. Barnard, 1932: 75. ―J.L. Barnard, 1969a: 354. ― Lowry, 1984: 99. ― Barnard & Karaman, 1991: 509. Type species . Pachychelium davidis Stephensen, 1925, by monotypy. Diagnostic description. Body shape slender. Head lateral cephalic lobe large, narrowly rounded . Antenna 1 peduncular article 1 without posterodistal spine; accessory flagellum article 1 long; [callynophore not known for female]. Mandible with accessory setal row absent; left lamina dentata absent; palp attached distally; palp article 2 broad, article 3 with subparallel margins or distally tapered. Maxilla 1 outer plate setal-teeth smooth, at least one inner row setal-tooth absent; palp absent. Maxilliped inner plate absent outer plate medium size; palp 3-articulate (article 4 absent) . Gnathopod 1 ischium smaller than propodus corner of palm with simple robust seta or without any robust seta. Gnathopod 2 palm obtuse. Epimeron 3 posteroventral corner broadly rounded . Uropod 3 biramous. Remarks. With the new species described from the boreal eastern North Pacific and the tropical western South Pacific and the reassignment of some species to Ultimachelium , the distribution of the previously bipolar genus Pachychelium is changed significantly. The sister taxon of Pachychelium appears to be Ultimachelium . The genera differ in the number of articles in the maxillipedal palp (article 4 absent in Pachychelium , large and well developed in Ultimachelium ) and in epimeron 3 which has a broadly rounded posteroventral corner in Pachychelium , projecting and narrowly rounded in Ultimachelium . Species composition. Pachychelium davidis Stephensen, 1925; P. fucaensis sp. nov. P. tropicalis sp. nov. Pachychelium antarcticum Schellenberg, 1926, is regarded as an unidentifiable taxon. : Published as part of Lowry, J. K. & Stoddart, H. E., 2012, The Pachynidae fam. nov. (Crustacea: Amphipoda: Lysianassoidea) 3246, pp. 1-69 in Zootaxa 3246 (1) on pages 31-32, DOI: 10.11646/zootaxa.3246.1.1, http://zenodo.org/record/5249007 : {"references": ["Stephensen, K. (1925) Crustacea Malacostraca, VI: (Amphipoda, II). Danish Ingolf-Expedition, 3 (9), 101 - 178.", "Schellenberg, A. (1926) Die Gammariden der deutschen Sudpolar-Expedition 1901 - 1903. Deutsche Sudpolar-Expedition, Zoology, 10, 18, 235 - 414.", "Barnard, K. H. (1932) Amphipoda. ' Discovery' Reports, 5, 1 - 326, pl. 1.", "Barnard, J. L. (1969 a) The families and genera of marine gammaridean Amphipoda. United States National Museum Bulletin, 271, 1 - 535.", "Lowry, J. K. (1984) Systematics of the pachynid group of lysianassoid Amphipoda (Crustacea). Records of the Australian Museum, 36 (2), 51 - 105.", "Barnard, J. L. & Karaman, G. S. (1991) The families and genera of marine gammaridean Amphipoda (except marine gammaroids). Records of the Australian Museum, Supplement, 13 (2), 419 - 866."]}