Different from M. dubia by the following features:
- Relatively shorter A1
- Shape and relative size of genital segment (greater in M. ferrarii)
- Relatively larger size 5th pedigerous segment
- No distal process on the outer lobe of P5
Different from M. dubioides by the following features:
- Relatively longer genital segment and shorter anal segment
- No distal process on the outer lobe of P5
- More robust body shape
- Presence of the ornamented protuberances in the cephalic area
White Sea (Kandalaksha Bay)
Female:
Cephalothorax is up to 61.3% of total body length. Oral papilla is slightly protuberant, located about 1/5 of the way on the ventral side of the cephalothorax. Well developed ocelli present with pigment cups medially fused. Cephalosome with irregular cuticular protuberances on the forehead.
A1 is about 1/4 of the length of the cephalothorax, 4-segmented.
Cephalosome and 1st thoracic segment are fused, each thoracic segment bears a pair of swimming legs.
P1-P4 slightly increase in size posteriorly, but their intercoxal sclerites decrease in size posteriorly. Intercoxal sclerites of P1-P4 are rectangular, without armature. Endopodites and exopodites of P1-P4 3-segmented.
P5 are medially fused at the base, unsegmented. Each leg consists of a relatively large (exopodal) lobe and an inner (endopodal) digiform lobe. 3 setae are present on the exopodal lobe, all unusually long.
Abdomen consists of 4 segments. Caudal rami are almost rectangular in shape, widely divergent, about 2.3 times longer than wide. Each carries 2 terminal, 1 outer and 1 inner setae.
Male:
unknown
