A new genus, Arktourella gen. nov., is proposed to accommodate a new member of the harpacticoid family Normanellidae,
A. margarethae gen. et sp. nov., from a polluted estuary in north-western Mexico. The new genus was attributed to
the laophontoidean family Normanellidae on account of the lack of outer spinous processes on the second antennulary
segment, one abexopodal seta on the antennary allobasis, four setae on the one-segmented antennary exopod, endopod of
first swimming leg two-segmented with first segment elongated and with two distal elements on second segment, endopods
of second to fourth legs two-segmented, distal setae on the male second endopodal segment of second and third legs
reduced, and outer spine of the male second endopodal segment of third leg fused to segment. The new, so far monotypic
genus, differs from the other normanellid genera in the presence of four elements on the third exopodal segment of the
first leg, and two outer spines on the third exopodal segment of second to fourth legs. No synapomorphies were observed
for Arktourella gen. nov. and Normanella, but they are unique within the Normanellidae in that the mandibular basis
and endopod are not fused. Maximum parsimony analysis and Bayesian inference using 59 morphological characters
to assess the relationships between the genera of the family Normanellidae confirmed the affinity of Arktourella gen.
nov. and Normanella, and their sister group relationship with Sagamiella. Paranaiara and Pseudocletodes were shown
consistently to be closely related and are the sister taxa of Normanella-Arktourella gen. nov.-Sagamiella. Arktourella gen.
nov., Paranaiara and Pseudocletodes share the presence of a large spinulose spine on the fifth and sixth segments of the
female antennule, but its significance is not clear. Additionally, we propose a key to the genera of the Normanellidae.
