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Müller, 1906

Diagnosis
Carapace of female is instantly recognisable in lateral aspect because of the strongly arcuate, almost semicircular, posterior margin and the opening of the left asymmetrical gland on a small distinct tubercle well to the anterior of the postero-dorsal corner (C. parthenoda Habitus 1). Right asymmetrical gland opens at postero-ventral corner. Males are similar in shape to males of C. hyalophyllum (Conchoecia hyalophyllum) and C. magna (Conchoecia magna) but, again, are quickly distinguishable by the anterior position of the left asymmetrical gland (C. parthenoda Habitus 3).
Female, frontal organ undifferentiated, straight and pointed (C. parthenoda 1). First antenna with rudimentary segmentation, the dorsal seta is bare.
Male, mrontal organ capitulum down-turned, spinose on its basal half, slightly constricted medially, terminally rounded (C. parthenoda 3). First antenna, "a" seta equal in length to second podomere, "c" seta minute, "b", "d" and "e" setae subequal, "e" seta armature 9-10 pairs of pointed spines replaced proximally by 15-18 alternating spines (C. parthenoda 4). Second antenna endopodite, "b" seta with sparse tuft of long hairs (C. parthenoda 5), right-hand hook appendage is angled twice through right angles, the left-hand just once.

Remarks
The males undescribed until Angel, 1969a distinguished them from C. hyalophyllum (Conchoecia hyalophyllum) and C. magna (Conchoecia magna). This species is intermediate between the magna group and the spinirostris group, and authors have alternated in attributing it to one or other group. Poulsen, 1973 erected his genus Spinoecia to include this species, but Martens, 1979 pointed out that, because no type species was designated, the name was a nomen nudum , and split Poulsen's genus into Porroecia and Obtusoecia. In equatorial regions there is another sibling species, C. pseudoparthenoda Angel, 1971, which shows even greater development of the posterior end in the female, with the left asymmetrical gland located even more anteriorly.

Distribution
Recorded from all oceans, 53°N-30°S in Atlantic. This is a shallow mesopelagic species most abundant at 100-500m which is rare at latitudes >40°. It seems to be advected northwards after the springtime onset of stratification. 1, 2 (R.R.S. Discovery Map).

Type specimens
None designated; status of original material uncertain.

Type locality
Original material described from 26°S-43°S in the South Atlantic.

Conchoecia parthenoda