Achelidelphys stellata ( Lafargue and Laubier, 1977 ) Lafargue and Laubier, 1977

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 : 61

Achelidelphys stellata ( Lafargue and Laubier, 1977) n. comb.

Syn: Cephalodelphys stellata Lafargue and Laubier, 1977

Material examined: Holotype female, reg. no. ZMA CO. 106.630.

Differential Diagnosis: Body highly transformed, stellate ( Fig. 12 A); segmentation indistinct with segmental boundaries marked by superficial folds. Cephalosome with broad, strongly-convex frontal margin merging laterally into large, ventrally-directed antennulary lobes ( Fig. 12 B). Rostrum ventrally-directed; simple rounded lobe. Post-rostral median lobe present. Labrum forming elongate, posteriorly-directed lobe. Lateral margin of cephalosome not produced into ridge-like swellings. Antenno-medial swellings also absent. Metasome truncated, with urosome hardly extending posterior to origin of leg 4. Legs 1–4 transformed, originating laterally, each occupying entire margin of somite, produced laterally giving body a stellate appearance. Mid-ventral metasomal processes between legs lacking. Urosome reduced, located terminally; incorporating caudal rami. Surface of body, rostrum, labrum, cephalosomic processes, and legs densely ornamented with surface setules ( Fig. 12 C).

Antennules forming large, rounded lobe on either side of convex frontal margin of cephalosome ( Fig. 12 D). Oral region with 3 pairs of tiny lobes, arranged either side of labrum; positions of lobes suggesting possible homology with mouthparts (mandibles to maxillae?). Legs 1 to 3 biramous; rami represented by unsegmented, rounded lobes; exopodal lobe laterally-directed, with broad base, carrying smaller endopodal lobe ventrally. Leg 4 uniramous, comprising short, posterolaterally-directed lobe representing exopod. Exopodal lobes of legs 2–4 each housing internal expansion of uterus, containing eggs visible through body wall. Leg 5 absent.

Body length of female 0.87–2.30 mm. Male unknown.

Remarks: This species has a strongly convex frontal margin to the cephalosome, but retains a rostrum. The phylogenetic analysis places this species within the Achelidelphys group of species ( Fig. 14 ) and does not support the retention of Cephalodelphys as a separate genus. Lafargue and Laubier (1977: Fig. 4 A) figured a small median ventral process (just posterior to the three pairs of oral lobes) concealed beneath the tip of the labrum but we were unable to confirm the presence of this structure in our re-examination of the holotype.

Figures

FIGURE 4. Anoplodelphys laubieri n. sp. holotype female (MNHN-Cp 2315). A, Cephalosome and first pedigerous somite, lateral; B, urosome, lateral. Anoplodelphys incerta Lafargue & Laubier, 1977, holotype female (ZMA CO. 106.602). C, Cephalosome and first pedigerous somite, ventral, D, Antennule showing surface ornamentation; E, Leg 5. Scale bars: A = 500 μm, B = 50 μm, C – D = 200 μm, E = 25 μm.

FIGURE 12. Achelidelphys reducta (Lafargue and Laubier, 1977) n. comb., holotype female (ZMA CO. 106.632). A, Habitus, ventral; B, Cephalosome, dorsal; C, Tip of exopodal lobe of leg 1, showing surface ornamentation. Achelidelphys stellata (Lafargue and Laubier, 1977) n. comb., holotype female (ZMA CO. 106.630). D, Cephalosome, dorsal; E, Tip of antennulary lobe, showing cluster of setae representing apex of limb; F, Urosome, dorsal; G, Post-rostral lobe, ventral view with surface removed showing internal support network of fibres. Scale bars: A – B = 500 μm, C = 100 μm, D = 200 μm, E – G = 100 μm.

FIGURE 14. Majority rule consensus tree showing estimated relationships between genera of Brementia - group with the family Notodelphyidae. The tree is the consensus of 10 equally parsimonious trees (branch length = 34). Values given above line are bootstrap values. Numbers below the line indicate the characters supporting the main clades. * Anoplodelphys incertae represents three taxa: A. incertae, A. galli and A. cf. galli, all of which have identical scores for the characters used in the analysis. Similarly, Achelidelphys chengae also represents Achelidelphys papuensis n. sp. which has identical scores for the characters used.