Paranoplodelphys simplex, Boxshall, Geoff A. & Marchenkov, Andrey, 2007

Boxshall, Geoff A. & Marchenkov, Andrey, 2007, A revision of the Brementia - group of genera (Copepoda: Notodelphyidae), with descriptions of a new genus and four new species, Zootaxa 1459, pp. 37-68 : 49-51

Paranoplodelphys simplex n. sp.

Type material: Holotype female, 2 paratype females. Registration nos: MNHN-Cp 2317 (Holotype in alcohol), MNHN-Cp 2318 (paratype female in alcohol), BMNH 2006.1188. (1 paratype female in alcohol).

Type Locality: Mescha island, Djibouti: collected at depth of 0–20 m, in 1996

Host: Didemnum dicolla Monniot and Monniot, 1999 [ MNHN reg. no. of host: A 2 DID C 397-401]

Locality in host: within the common tunic between the zooids (F. Monniot, pers. comm.).

Etymology: the species name refers to the extreme reduction in limbs exhibited by this species.

Description: Adult female body ( Fig. 5 A–D) highly transformed, vermiform and lacking external segmentation: indistinctly divided into 3 regions, cephalosome, metasome and urosome, by shallow furrows. Body length of holotype female 1.63 mm (ranging from 1.63–1.70 mm for 3 studied specimens). Cephalosome with broad, rounded frontal margin; bearing single pair of appendages (antennules) ventrolaterally, and strongly developed labrum. Rostrum absent. Metasome more or less cylindrical, but tapering posteriorly; bearing 2 pairs of legs (legs 1 and 2). Developing eggs in uterus visible through body wall ( Fig. 5 C). Metasome lacking expressed segmentation but with visible cuticular folds indicating division into 4 somites; fourth somite bearing urosome inserted dorsally. Urosome ( Fig. 5 E) reduced, unsegmented, incorporating caudal rami represented by cluster of caudal setae ( Fig. 5 E). Entire body surface densely ornamented with relatively short setules, similar to those of A. africana (cf. Fig. 1 D).

Antennules ( Fig. 5 A–B, D) extremely reduced, represented by pair of small conical protrusions located near anterolateral corners of labrum. No other cephalosomal appendages observed.

Labrum ( Fig. 5 A–B, D) massive, conical, with rounded posterior tip reaching anterior border of base of leg 2. Surface of labrum ornamented with setules.

Legs 1 and 2 only present ( Fig. 5 A–B, D); legs 3 and 4 absent. Legs 1 and 2 originating close to each other, just behind cephalosome. Leg 1 biramous, with common protopodal base bearing unsegmented, conical rami; endopodal lobe elongate, massive, exopodal lobe very reduced. Leg 2 uniramous, unsegmented, present as conical process half as long as endopodal lobe of leg 1.

Leg 5 ( Fig. 5 E–F) well developed as simple lobes armed with 2 setae located near anterior margin of urosome: 1 seta apical, other subapical.

Male unknown.

Remarks: The new species can be distinguished from all other species attributed to the Brementia -group of genera by extreme reduction: in particular by the absence of a rostrum, the loss of the antenna and all oral appendages, by the decrease in size of the exopodal lobe of leg I, and by the possession of a uniramous leg 2. Without access to developmental stages it is not possible to identify the homology of the remaining ramus on leg 2.