Pachychelium Stephensen, 1925

Lowry, J. K. & Stoddart, H. E., 2012, The Pachynidae fam. nov. (Crustacea: Amphipoda: Lysianassoidea) 3246, Zootaxa 3246 (1), pp. 1-69: 31-32

publication ID

http://doi.org/ 10.11646/zootaxa.3246.1.1

DOI

http://doi.org/10.5281/zenodo.5251234

persistent identifier

http://treatment.plazi.org/id/456087D3-363B-FF96-B8DF-0CC9FBDB4CD8

treatment provided by

Felipe

scientific name

Pachychelium Stephensen, 1925
status

 

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.

Kingdom

Animalia

Phylum

Arthropoda

Class

Malacostraca

Order

Amphipoda

Family

Pakynidae

Loc

Pachychelium Stephensen, 1925

Lowry, J. K. & Stoddart, H. E. 2012
2012
Loc

Pachychelium

Barnard, J. L. & Karaman, G. S. 1991: 509
Lowry, J. K. 1984: 99
Barnard, J. L. 1969: 354
Barnard, K. H. 1932: 75
Schellenberg, A. 1926: 296
Stephensen, K. 1925: 121
1925