Mesamphisopus : Nicholls 1943
Creators: name: Gouws, Gavin
Publisher: name: Zenodo
Year: 2008
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Isopoda
Mesamphisopidae
Mesamphisopus

description: Key to the known species of Mesamphisopus   
1 Antennal basal articles sparsely to moderately setose............................................................................... 2  
– Antennal basal articles heavily setose....................................................................................................... 3  
 2 Pleotelson dorsal margin straight, apex continuous with and at same level as anterior dorsal margin (ventral inflection absent or very shallow), apex long and not up-turned.................................... M. paludosus   
 – Pleotelson dorsal margin gradually curving downwards with deep ventral inflection, apex below level of anterior dorsal margin, apex long and up-turned or very short........................................... M. penicillatus   
3 Uropodal protopod dorsomesial margin/ridge produced to some extent and plate-like............................ 4  
 – Uropodal protopod dorsomesial margin approximately linear, not produced........................ M. tsitsikamma   
4 Pleotelson with subapical pair of dorsal robust setae................................................................................ 5  
– Pleotelson without subapical pair of dorsal robust setae........................................................................... 6  
 5 Cephalon and pereon sparsely to moderately setose; antennula with 5 or 6 articles; pleotelson abrupt, stubby, dorsal margin sloping steeply with shallow ventral inflection, apex indefinite and hardly upturned; elongate setae abundant on uropodal rami............................................................. M. abbreviatus   
 – Cephalon and pereon with abundant elongate setae, particularly laterally; antennula with 7 or 8 articles; pleotelson dorsal margin sloping gradually, ventral inflection deep, apex broad, small and up-turned; elongate setae sparse on uropodal rami or absent.......................................................................... M. depressus   
 6 Eyes small, diameter less than half the width of proximal antennal article and <0.10 head depth; body lacking pigmentation................................................................................................................. M. albidus   
– Eyes larger, diameter approximately half width of proximal antennal article and> 0.10 head depth; body pigmented or weakly pigmented................................................................................................................ 7  
 7 Antennula short (<0.15 body length); antenna long (> 0.60 body length); pereopod I with distoventral cuticular process on propodal palm;> 10 robust setae on each of uropodal rami; body weakly pigmented..................................................................................................................................................... M. setosus   
– Antennula long (> 0.15 body length); antenna short (<0.60 body length); pereopod I without distoventral cuticular process on propodal palm; <6 robust setae on each of uropodal rami; body strongly pigmented.................................................................................................................................................................... 8  
 8 Pereopod I dactylus distoventral row of scale-like spines absent or weakly developed; pleotelson lateral uropodal ridge absent/weakly developed; abundant elongate setae on uropodal protopod and rami............................................................................................................................................................. M. kensleyi   
– Pereopod I dactylus distoventral row of scale-like spines well developed; pleotelson lateral uropodal ridge well developed; elongate setae on uropodal protopod and rami sparse to common................................. 9  
 9 Antennular and antennal articles short, broad, inflated and bulbous; setae common to abundant on pereon and pleon.................................................................................................................................. M. baccatus   
 – Antennular and antennal articles long, slender, broadly rectangular; pereon and pleon sparsely setose....................................................................................................................................................... M. capensis
description: Published as part of Gouws, Gavin, 2008, New species of Mesamphisopus, an endemic South African freshwater isopod genus (Isopoda: Phreatoicidea: Mesamphisopidae), pp. 1-62 in Zootaxa 1690 on pages 59-60