The systematic location of Puncia and Manawa is puzzling, as they are so unlike any other known living Ostracoda. No ordinal placing has been attempted, as the sub-orders of living Ostracoda are based on appendages. These two forms evidently form a natural group and have essentially the same type of structure, except for the bracket-like teeth of Manawa, which at first suggest possible Cytherid affinities. This type of bracket-hinge appears, however, to be quite unique amongst the Ostracoda and quite different from anything seen in the Cytheridae, which have a tooth-and-socket arrangement comparable to the bivalve Mollusca. The “frilled” structure of the valves is paralleled only by the Palaeozoic Eurychilininae in which the frill is interpreted as a double-walled, septate structure by Swartz (in litt.),
Figs. 1–6–Puncia novozealandica n.gen., n.sp.
Fig. 1—light valve (holotype), × 135. Kg. 2–right valve, dorsal aspect (holotype), × 105. l fig. 3–right valve (holotype), × 95.
Fig. 4–juvenile, left valve, × 105. Fig. 5–right valve, internal lateral aspect (holotype), × 105. Fig. 0–juvenile, and view, × 100.
Fig. 7—Eurychilina reticulata, Ulrich. × 20. Ordovician. (After Bassler and Kellett, 1934.)
Figs. 8, 9–Chilobolbina dentifera Bonnemma. Ordovician. Left valves of male and female with brood pouch. × 15. (After Bassler and Kellett, 1934.)
Figs. 1–8–Manawa. tryphena n. gen., n.sp.
Fig. 1–right valve (holotype), × 90. Fig. 2–right valve, internal gen., n.sp.al aspect (holotype), × 80. Fig. 3–left valve (paratype), × 90. Fit.
Fig. 1–right valve (holotype), × 90. Fig. 2–right valve, internal valve, dorsal aspect (paratype), × 90. Gig. 6–right valve, dorsal aspect (holotype), × 90. Fig. 7–right valve, and view (holotype), × 92. Fig. (8–left valve, and view (paratype),-X 90.
who suggests that this internal structure should enhance the significance of the frill as a guide to genetic relationships and together with the associated dimorphic brood pouches should prove to be a major guide in the arrangement of the straight-backed family Beyrichiidae. It may be reasonably conjectured that the frill of Puncia and Manawa is of reproductive significance from analogy with the Eurychilinas, many of which develop an associated brood pouch. There is no evidence of any such brood pouch in the single valve of Puncia examined, but no conclusion can as yet be reached on this point without further material. Puncia, with its straight hinge, median sulcus, radially septate frill and semi-elliptical form with a pronounced backwards swing is a very close duplication of the Palaeozoic genus Chilobolbina and would almost certainly be placed in the subfamily Eurychilininae if it were found in Palaeozoic rocks. In spite of this remarkable resemblance the author is reluctant to assert that a representative of a group of Ostracoda, which apparently died out elsewhere in the Devonian, is still living in the South Pacific. Nevertheless, it does seem at least plausible that this case may be analogous to the discovery of living Crinoids, particularly in view of the fact that the Ostracod fauna of the South Pacific deeps is largely unknown. It may be, on the other hand, that this is a particularly striking example of parallel evolution.
The problem of the orientation of the valves is much the same as in the Beyrichiidae. There seems little reason to try and homologise the blunt or “plenate” end with the plenate end of other modern Ostracoda. The author has tended rather to look for analogy with those Palaeozoic forms with which Puncia seems to have its affinities and he believes that a very strong clue as to the anterior end of Puncia is to be found in the orientation of the dorso-lateral horn like prominences. In modern forms, where alar projections are present, they are backwardly directed, presumably to minimise the resistance of the water when the animals are moving forwards. This strongly suggests that the tendency for the paired prominences in Puncia to lean towards the plenate end is of direct and functional significance in the orientation of the carapace, and in the absence of further evidence the plenate end is here regarded as posterior in both forms. This is in agreement with the conclusions reached by Ulrich and Bassler (1908) from the location of brood pouches in Palaeozoic Ostracoda.
At present these two strange forms are known only from the Three-Kings-North-Cape area in fairly deep water and accompanied by a rich fauna of warm-water species. It seems likely to the author that future dredging operations in the South Pacific will bring to light other members of this family and perhaps specimens with the appendages intact, in which event the problem of the orientation of the Palaeozoic Beyrichiidae may be finally solved.